JP3353689B2 - Internal combustion engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lean combustion control in which an air-fuel ratio is lower than the stoichiometric air-fuel ratio, and a mixture having a stoichiometric air-fuel ratio or a richer air-fuel ratio than the stoichiometric air-fuel ratio. The present invention relates to an internal combustion engine control device for performing stoichiometric rich combustion control of burning with air.

[0002]

2. Description of the Related Art Conventionally, there is known a variable valve timing apparatus which adjusts and controls the rotational phase difference between an intake camshaft and an exhaust camshaft with respect to a crankshaft to one of two, large or small, in order to improve the output of an internal combustion engine. Have been. Such a variable valve timing device,
When the internal combustion engine is running at high speed, the valve overlap is switched from small to large by adjusting the rotational phase difference of the camshaft to increase the output torque, and when the engine is running at low speed, the valve overlap is switched from large to small to maintain combustion stability. It is to try to make it.

[0003] However, when the valve overlap is switched from small to large while the internal combustion engine is performing lean (lean) combustion control, the residual gas increases in the combustion chamber and the combustion stability deteriorates. Occurred. For this reason, in the technique disclosed in Japanese Patent Application Laid-Open No. 5-33715, the valve overlap amount (O / L) is increased by disabling the timing of the air-fuel ratio control and the valve overlap control as shown in FIG. And the lean state of the air-fuel ratio (A / F) are prevented from overlapping, thereby achieving combustion stability.

[0004]

In the prior art described above, the valve overlap amount is switched between large and small stages. However, if the valve overlap amount between these two stages is switched in accordance with the operating state, As shown below,
It has been found that the output torque of the internal combustion engine involves a large fluctuation at the time of switching, and a torque shock occurs to reduce drivability, as compared with the case where switching from the optimal valve overlap amount is performed according to all operating conditions.

Here, at a certain rotational speed of the internal combustion engine,
The optimum pattern of the valve overlap amount necessary for improving the fuel efficiency and the emission of the internal combustion engine is as shown in FIG. The pattern shown by the solid line is the optimum valve overlap amount in the stoichiometric rich combustion control, and the pattern shown by the dashed line is the optimum valve overlap amount in the lean combustion control.

When a two-stage valve overlap amount is set as in the prior art, in order to obtain a sufficient output torque corresponding to the fully open state (WOT) of the throttle valve, the stoichiometric-rich combustion control is performed. The optimum valve overlap amount O / L (WOT) at the time of WOT is set as the large valve overlap amount. On the small side of the valve overlap amount, the minimum valve overlap amount O / L (1) in the lean combustion control is set in order to obtain combustion stability in all regions.

[0007] Then, as shown in FIG. 25, a point B of the load at which the pattern in the stoichiometric rich combustion control is divided into upper and lower portions is set with the valve overlap amount O / L (WOT) as a boundary. As a result, when the load is lower than the switching point B, the valve overlap amount does not become excessive in both the lean combustion control and the stoichiometric rich combustion control, and the combustion stability can be maintained.

However, as described above, the change in the valve overlap amount [O / L (WOT) -O / L (1)] at the switching point B is not optimal because of the two-stage setting. Change between valve overlaps [O / L
(WOT) −O / L (3)], which is a considerably large change. For this reason, in the related art in which the switching is performed in two stages, a large change in the valve overlap amount cannot be avoided at the time of switching, and a torque shock is generated to reduce drivability.

By changing the large side of the valve overlap amount to a small value O / L (C) and setting the switching point lower than the point B and setting it to the point C shown in FIG. It is conceivable to reduce the step of the lap amount and widen the switchable region of the valve overlap amount. However, in this case, the valve overlap amount is insufficient at the time of WOT, and a sufficient output torque cannot be obtained.

Further, as shown in FIG.
On the lower load side, for example, on the load GNL, of the two stages,
Since only the smaller valve overlap amount O / L (1) can be obtained, in both the lean combustion control and the stoichiometric-rich combustion control, the valve overlap amount is smaller than the appropriate valve overlap amount (indicated by ● or ▲) in almost all regions. The valve overlap amount (represented by ○ or Δ) is obtained, and the internal EGR is reduced as compared with the case of the optimal valve overlap amount, which causes emission or fuel consumption to deteriorate. On the load side higher than the switching point B, for example, on the load GNH, the valve overlap amounts O / L (1) and O / L (WOT) of the two stages can be taken depending on the operation state. In both the control and the stoichiometric-rich combustion control, the valve overlap amount (represented by ○ or）) is smaller than the appropriate valve overlap amount (represented by ● or ▲) over almost the entire range, and the optimum valve overlap amount is determined. The internal EGR decreases as compared with the case, and the emission or the fuel consumption deteriorates. FIG. 27A shows poor fuel economy in the related art as compared with the optimal valve overlap amount.

Further, there is a problem that emission is deteriorated because an optimum valve overlap amount cannot be obtained with respect to the air-fuel ratio. FIG. 27B shows poor emission (here, an example of NOx) in the prior art as compared to the optimum valve overlap amount.

In FIG. 27, it can be seen that both the fuel consumption and the emission are deteriorated in the prior art of two-stage switching represented by ○ or 比較, as compared with the case of the optimum valve overlap amount represented by ま た は or ▲.

It is an object of the present invention to prevent torque shock at the time of switching the valve overlap amount by the above-described variable valve timing device, realize good drivability, and also improve fuel efficiency and emission. It is.

[0014]

According to a first aspect of the present invention, there is provided an internal combustion engine control device that controls a lean combustion control in which the air-fuel ratio is lower than a stoichiometric air-fuel ratio in accordance with an operating state of the internal combustion engine. An internal combustion engine control device for performing stoichiometric rich combustion control for burning with air or a mixture richer than the stoichiometric air-fuel ratio, wherein the valve overlap amount between an intake valve and an exhaust valve of a combustion chamber of the internal combustion engine is continuously adjusted. A variable valve timing mechanism that can be adjusted; a first storage unit that stores a setting pattern of a valve overlap amount that is adjusted by the variable valve timing mechanism in accordance with an operation state of the internal combustion engine during the lean combustion control; Valve over which is adjusted by the variable valve timing mechanism according to the operating state of the internal combustion engine during the stoichiometric rich combustion control Second storage means for storing a set pattern of the amount of stop, combustion control state determination means for determining whether the operation state of the internal combustion engine is a lean combustion control state or a stoichiometric rich combustion control state, and the combustion control state determination means When it is determined that the operating state of the internal combustion engine is the lean combustion control state, the operating state of the internal combustion engine is determined based on the valve overlap amount setting pattern stored in the first storage means. The valve overlap amount adjusted by the variable valve timing mechanism is set in accordance with the above. When it is determined that the operation state of the internal combustion engine is the stoichiometric rich combustion control state, the second storage means is stored in the second storage means. Adjustable by the variable valve timing mechanism in accordance with the operating state of the internal combustion engine based on the stored setting pattern of the valve overlap amount. A valve timing control means for setting the valve overlap amount, the inner
Whether the combustion fluctuation of the fuel engine is larger than the combustion fluctuation judgment value a
Combustion fluctuation determining means a for determining whether the combustion control state
Stoichiometric rich combustion control is performed by the determination means
And the combustion fluctuation is determined by the combustion fluctuation determining means a.
Is determined to be larger than the combustion variation determination value a.
The valve set by the valve timing control means
Compensate the overlap amount in a direction to reduce combustion fluctuation.
Stoichiometric rich correction means .

In the internal combustion engine control apparatus according to the first aspect of the present invention, the first storage means stores the set pattern of the valve overlap amount which is continuously set by the variable valve timing mechanism in the lean combustion control and the stoichiometric rich combustion control. It is stored in the second storage means. When the operating state of the internal combustion engine is in the lean combustion control state, the valve timing control means controls the variable valve timing mechanism based on the set pattern of the valve overlap amount for lean combustion control stored in the first storage means. If the operating state of the internal combustion engine is the stoichiometric rich combustion control state, the variable valve timing mechanism is controlled based on the stoichiometric rich combustion control valve overlap amount setting pattern stored in the second storage means. Drive.

As described above, by using the variable valve timing mechanism capable of continuously adjusting the valve overlap amount between the intake valve and the exhaust valve of the combustion chamber, the lean combustion control and the stoichiometric rich combustion control can be performed. The valve overlap amount can be adjusted to an optimal pattern according to the operation state of the internal combustion engine.

Therefore, as described in the section of "Problems to be Solved by the Invention", the above set patterns are used for lean combustion control and stoichiometric control as compared with the case where control is performed using only two stages of valve overlap. -When switching for rich combustion control, the step of the valve overlap amount at the time of switching the valve overlap amount is small, and the change in torque output is correspondingly small. Therefore, good drivability can be realized by preventing torque shock. Further, improvement in fuel efficiency and emission can be realized for the above-mentioned reason. Also, like this,
-If combustion fluctuations occur during rich combustion control,
Instead of reducing combustion fluctuation by ratio, variable valve
Adjust the valve overlap amount by the timing mechanism
Therefore, it does not affect the air-fuel ratio. Therefore, three
Do not affect the purification performance of exhaust gas
Therefore, combustion fluctuation can be reduced.

The setting pattern of the valve overlap amount does not need to be directly represented by the valve overlap amount. For example, the pattern of the advance or retard amount of the intake valve or the exhaust valve may be changed. May be used as long as it is a physical quantity corresponding to the valve overlap amount.

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

As described in claim 2 , the stoichiometric rich correction means is configured to feedback-control the valve overlap amount so that the combustion fluctuation converges on the combustion fluctuation determination value a. Is also good.

As described above, since the combustion fluctuation is converged by the feedback control, the combustion fluctuation can be suppressed without correcting the valve overlap amount unnecessarily.
The invention according to claim 3 responds to the operating state of the internal combustion engine.
The lean air-fuel ratio is lower than the stoichiometric air-fuel ratio.
Combustion control and stoichiometric air-fuel mixture or stoichiometric air-fuel ratio
Stoichiometric rich combustion control to burn with rich mixture
An internal combustion engine control device that performs
The amount of valve overlap between the intake valve and the exhaust valve
A variable valve timing mechanism that can be continuously adjusted;
According to the operating state of the internal combustion engine during lean combustion control
The valve adjusted by the variable valve timing mechanism.
First storage for storing a set pattern of overlap amount
Means and internal combustion during stoichiometric rich combustion control
The variable valve timing corresponds to the operating state of the engine.
Setting pattern of valve overlap amount adjusted by mechanism
Storage means for storing an operation state of the internal combustion engine.
Lean combustion control state or stoichiometric rich combustion control
Combustion control state determination means for determining whether the combustion state
The control state determination means determines that the operating state of the internal combustion engine is lean.
If it is determined that the state is the burning control state, the first storage
Means for setting the valve overlap amount stored in the means.
Based on the constant pattern, corresponding to the operating state of the internal combustion engine
The valve is adjusted by the variable valve timing mechanism.
-Set the lap lap amount and stop the operation of the internal combustion engine.
If it is determined that the state is the key rich combustion control state,
The valve over stored in the second storage means
Based on the lap amount setting pattern, the operation status of the internal combustion engine
Adjusted by the variable valve timing mechanism according to the
Valve timing to set the valve overlap amount
Control means and the combustion fluctuation of the internal combustion engine is a combustion fluctuation judgment value b
Combustion fluctuation determining means b for determining whether the value is greater than
Lean combustion control is performed by the combustion control state determination means.
And the combustion fluctuation determination means b
If it is determined that the burning fluctuation is greater than the combustion fluctuation determination value b,
If the air-fuel ratio of the air-fuel mixture is
Lean correction means for correcting the direction.
And Further, as shown in claim 4 , claim 1 or
In the configuration of the internal combustion engine control device described in 2, the combustion variation determination means b for determining whether the combustion variation of the internal combustion engine is greater than the combustion variation determination value b, and the combustion control state determination means When it is determined that the lean combustion control is being performed, and when the combustion variation determining means b determines that the combustion variation is greater than the combustion variation determination value b, the air-fuel ratio of the air-fuel mixture is reduced, and the combustion variation is reduced. The control device can be configured as an internal combustion engine control device including a lean correction means for correcting in a certain direction.

In the case of the lean combustion control, the exhaust gas purification performance is already in a state where the exhaust gas cannot be exhibited. Therefore, even if the air-fuel ratio is changed, the purification of the exhaust gas is not affected. In addition, since the generation of NOx and the like is reduced in the lean combustion, control is performed to reduce the combustion fluctuation by the air-fuel ratio of the air-fuel mixture. In this way, if the combustion fluctuation is suppressed by adjusting the air-fuel ratio, unlike the adjustment by the mechanical variable valve timing mechanism, the soft control is the main, so the response is high and the combustion fluctuation is suppressed very quickly. be able to.

According to a fifth aspect of the present invention, the lean correction means may be configured to feedback control the air-fuel ratio of the air-fuel mixture so that the combustion fluctuation converges on the combustion fluctuation determination value b. Good.

As described above, since the combustion fluctuation is converged by the feedback control, the combustion fluctuation can be suppressed without unnecessarily correcting the air-fuel ratio. In addition, as shown in claim 6 , with respect to the configuration of the internal combustion engine control device according to any one of claims 3 to 5, a combustion variation determination value c set to a value smaller than the combustion variation determination value b is obtained. Also, a combustion fluctuation determining means c for determining whether the combustion fluctuation of the internal combustion engine is large, and a second lean time in which the valve overlap amount set by the valve timing control means is corrected in a direction in which the combustion fluctuation becomes small. Correction means, and the combustion control state determination means determines that lean combustion control is being performed, and the combustion fluctuation determination means c has determined that combustion fluctuation is greater than the combustion fluctuation determination value c. In this case, the lean-time correction means is caused to function, the combustion control state determination means determines that the lean combustion control is being performed, and the combustion fluctuation determination means c determines that the combustion fluctuation has occurred. If it is determined to be smaller than the dynamic determination value c can be configured as an internal combustion engine control apparatus to function said second lean time correcting means.

Even in the lean combustion control, when the combustion fluctuation is small, the combustion fluctuation can be suppressed sufficiently quickly by adjusting the valve overlap amount even if the response is not high as in the air-fuel ratio adjustment. And the fuel economy can be kept low. Further, when the combustion fluctuation is large, stable combustion can be achieved early by adjusting the air-fuel ratio, so that the drivability does not deteriorate.

Also in this case, as described in claim 7 , the second lean correction means is configured to feedback-control the valve overlap amount so that the combustion fluctuation converges on the combustion fluctuation judgment value d. You may.

As described above, since the combustion fluctuation is converged by the feedback control, the combustion fluctuation can be suppressed without unnecessarily correcting the valve overlap amount.
According to an eighth aspect of the present invention, in the configuration of the internal combustion engine control device according to the sixth or seventh aspect, the correction of the air-fuel ratio of the air-fuel mixture by the lean-time correction means is performed by a concentration determination. The combustion control state determining unit determines that lean combustion control is being performed, and the combustion variation determining unit includes a concentration adjustment determining unit that determines whether the mixture is adjusted to a mixture richer than a reference value. If it is determined in step c that the combustion fluctuation is smaller than the combustion fluctuation determination value c, the correction of the air-fuel ratio of the air-fuel mixture is adjusted by the concentration adjustment determination unit to a mixture richer than the concentration determination reference value. When it is determined that the vehicle is in the internal combustion engine, it is possible to configure the internal combustion engine control device to function the lean time correction means without operating the second lean time correction means.

That is, when the combustion fluctuation is smaller than the combustion fluctuation judgment value c and the air-fuel mixture is corrected to the air-fuel mixture higher than the concentration judgment reference value, when the lean time correction means is operated, the combustion fluctuation is reduced. The control position can be returned to a direction in which the combustion fluctuation increases in an allowable range, that is, a control position where the air-fuel ratio becomes as lean as possible. As a result, instead of increasing the valve overlap amount, the air-fuel ratio can be made as lean as possible, and the fuel efficiency can be further improved.

Also, as shown in claim 9 , claim 3
The internal combustion engine control device according to any one of claims 1 to 5, further comprising: an internal combustion engine rotation speed determination unit configured to detect a rotation speed of the internal combustion engine and determine whether the rotation speed is greater than a determination rotation speed. A third lean correction means for correcting the valve overlap amount set by the valve timing control means in a direction in which combustion fluctuations are reduced, and lean combustion control is performed by the combustion control state determination means. If it is determined that the engine is running, and if the internal combustion engine speed determining means determines that the rotational speed is smaller than the determined rotational speed, the lean time correction means is caused to function, and the combustion control state determining means determines that the engine is lean. If it is determined that the combustion control is being performed, and if the internal combustion engine speed determination means determines that the rotation speed is higher than the determination rotation speed, the third lean correction means is activated. It can be constructed as an internal combustion engine control device that.

That is, even during the lean combustion control,
Based on the rotation speed of the internal combustion engine, the combustion fluctuation is suppressed by adjusting the valve overlap amount on the high rotation side, and the combustion fluctuation is suppressed by adjusting the air-fuel ratio on the low rotation side.

According to the adjustment of the valve overlap amount,
Although it is advantageous for both fuel consumption and emission, when the internal combustion engine is running at low speed, the variable valve timing mechanism is slow to drive and the response is poor, so in lean combustion control, the combustion fluctuation is suppressed by adjusting the air-fuel ratio on the low speed side. are doing. However, on the high rotation side, the variable valve timing mechanism is driven quickly and has good responsiveness, so that it does not affect combustion stability and does not deteriorate drivability. Combustion fluctuation is suppressed by adjustment. Therefore, combustion fluctuations can be quickly suppressed regardless of the rotational speed of the internal combustion engine, and efforts can be made to improve fuel economy and emissions as much as possible.

Also in this case, as shown in claim 10 ,
The third lean correction means may be configured to feedback-control the valve overlap amount so that the combustion fluctuation converges on the combustion fluctuation determination value e.

As described above, since the combustion fluctuation is converged by the feedback control, the combustion fluctuation can be suppressed without unnecessarily correcting the valve overlap amount.
Further, as shown in claim 1 1, the configuration of an internal combustion engine control apparatus according to any one of claims 3 to 1 0, with the variable valve timing mechanism to function by the supply of hydraulic fluid, said hydraulic fluid Hydraulic fluid temperature detecting means for detecting the temperature of the hydraulic fluid, hydraulic fluid temperature determining means for determining whether or not the temperature of the hydraulic fluid detected by the hydraulic fluid temperature detecting means is within an allowable temperature range; If the liquid temperature determining means determines that the temperature of the hydraulic fluid is not within the allowable temperature range, a correction for prohibiting the second lean correcting means or the third lean correcting means from functioning. The control device may be configured as an internal combustion engine control device including a prohibition unit.

When the working fluid such as lubricating oil is at a low temperature, the friction of the variable valve timing mechanism is increased. When the working fluid is at a high temperature, the hydraulic pressure is reduced due to liquid leakage, and the driving of the variable valve timing mechanism is slowed down. The responsiveness of the valve overlap amount adjustment decreases. Therefore, when the temperature is outside the allowable temperature range, the suppression of combustion fluctuation by correcting the valve overlap amount is prohibited. This can prevent unstable combustion and deterioration of fuel efficiency and emission.

[0043] Further, as shown in claim 1 2, wherein the correction inhibiting means, at the hydraulic fluid temperature determining means, when the temperature of the hydraulic fluid is determined not to exist in the allowable temperature range, the The second lean correction means or the third lean correction means may be inhibited from functioning, and the lean correction means may function. Thus, when it is inappropriate to adjust the valve overlap amount due to the temperature of the hydraulic fluid, it is possible to suppress the combustion fluctuation with the air-fuel ratio of the air-fuel mixture and maintain stable combustion. it can.

According to a thirteenth aspect of the present invention, an operation of an internal combustion engine is provided.
Depending on the rotation state, combustion with a mixture that is thinner than the stoichiometric air-fuel ratio
Lean combustion control and stoichiometric air / fuel mixture or theory
Stoichi-rich to burn with a mixture richer than the air-fuel ratio
An internal combustion engine control device for performing combustion control, comprising:
Of the combustion chamber intake valve and exhaust valve
Variable valve timing machine that can continuously adjust the lap amount
Operating state of the internal combustion engine during the lean combustion control
Adjusted by the variable valve timing mechanism according to the condition
The set pattern of the valve overlap amount
First storage means for controlling the stoichiometric-rich combustion control.
The variable valve according to the operating state of the internal combustion engine in
Valve overlap amount adjusted by timing mechanism
Storage means for storing the set pattern of the internal combustion engine;
If the operation state is lean combustion control state or stoichiometric
Control state determining means for determining whether the switch is in a combustion control state
Operating state of the internal combustion engine by the combustion control state determining means.
If it is determined that the state is the lean combustion control state,
The valve over stored in the first storage means
Based on the lap amount setting pattern, the operation status of the internal combustion engine
Adjusted by the variable valve timing mechanism according to the
Set the valve overlap amount to operate the internal combustion engine
It is determined that the state is the stoichiometric rich combustion control state.
In this case, the buffer stored in the second storage means is
Based on the setting pattern of the lube overlap amount, the internal combustion
The variable valve timing machine according to the operating state of the engine
A valve that sets the valve overlap amount
Lube timing control means and the combustion control state determination means
, The operation state of the internal combustion engine is in the lean combustion control state
From the determination that the stoichiometric-rich combustion control state is established.
When switching to the determination of the above, the valve timing control
Of the valve overlap amount used in the means
The setting pattern stored in the first storage unit is stored.
The setting stored in the second storage means from the fixed pattern
It is equipped with a gradual change means to gradually switch to the pattern.
Sign. Also as shown in claim 1 4, claim 1
The configuration of the internal combustion engine control device 1 2 according to any one at the combustion control state determining means, from the determination of the operating state of the internal combustion engine is a lean burn control state, the stoichiometric - rich combustion control state When switching to the determination that there is, the setting pattern of the valve overlap amount used in the valve timing control means is changed from the setting pattern stored in the first storage means to the second pattern.
The control device may be configured as an internal combustion engine control device including a gradual change unit that gradually switches to the setting pattern stored in the storage unit.

As described above, when the setting pattern is switched from the setting pattern stored in the first storage means to the setting pattern stored in the second storage means, the setting pattern is not switched all at once, but is switched gradually. As a result, the sudden change and rise of the output torque can be moderated, so that torque shock can be prevented and drivability can be further improved.

[0046] As shown in claim 1 5, claim 1 3 or
In the configuration of the internal combustion engine control device described in Item 14 or 14, the acceleration request detection means for detecting the degree of the acceleration request to the internal combustion engine and the acceleration request detection means have an acceleration request larger than the acceleration request determination value. In this case, the control device may be configured as an internal combustion engine control device including gradual change prohibition means that does not function the gradual change means. That is, when sudden acceleration is required by the driver's operation, the switching of the set pattern is stopped gradually, and a sudden change of the set pattern is allowed to respond to the driver's request.

When the driver is requesting rapid acceleration, even if the torque increases rapidly, the driver does not feel as a torque shock but feels good acceleration, and conversely, gradually increases the torque. The driver feels that the acceleration responsiveness is degraded, so that at the time of rapid acceleration, it is prohibited to gradually switch the set pattern, and good drivability is maintained.

According to a sixteenth aspect of the present invention, an operation of an internal combustion engine is provided.
Depending on the rotation state, combustion with a mixture that is thinner than the stoichiometric air-fuel ratio
Lean combustion control and stoichiometric air / fuel mixture or theory
Stoichi-rich to burn with a mixture richer than the air-fuel ratio
An internal combustion engine control device for performing combustion control, comprising:
Of the combustion chamber intake valve and exhaust valve
Variable valve timing machine that can continuously adjust the lap amount
Operating state of the internal combustion engine during the lean combustion control
Adjusted by the variable valve timing mechanism according to the condition
The set pattern of the valve overlap amount
First storage means for controlling the stoichiometric-rich combustion control.
The variable valve according to the operating state of the internal combustion engine in
Valve overlap amount adjusted by timing mechanism
Storage means for storing the set pattern of the internal combustion engine;
If the operation state is lean combustion control state or stoichiometric
Control state determining means for determining whether the switch is in a combustion control state
Operating state of the internal combustion engine by the combustion control state determining means.
If it is determined that the state is the lean combustion control state,
The valve over stored in the first storage means
Based on the lap amount setting pattern, the operation status of the internal combustion engine
Adjusted by the variable valve timing mechanism according to the
Set the valve overlap amount to operate the internal combustion engine
It is determined that the state is the stoichiometric rich combustion control state.
In this case, the buffer stored in the second storage means is
Based on the setting pattern of the lube overlap amount, the internal combustion
The variable valve timing machine according to the operating state of the engine
A valve that sets the valve overlap amount
LU timing control means, the first storage means and
The valve overlap amount stored in the second storage means
The setting pattern is the load of the internal combustion engine and the rotation speed of the internal combustion engine.
Of the valve overlap amount with the parameters
It is characterized by being. Further, as set forth in claim 17 , the internal combustion engine control device according to any one of claims 1 to 15 is provided.
With respect to the configuration of the device, the setting pattern of the valve overlap amount stored in the first storage means and the second storage means is such that the load of the internal combustion engine and the rotation speed of the internal combustion engine are used as parameters. It may be realized as a map of quantity. According to such a map, it is possible to precisely adjust the valve overlap amount according to the operation state. Further, the invention described in claim 18 is the invention according to claims 1 to 17.
The configuration of any of the internal combustion engine control devices
A flow resistor capable of adjusting the flow resistance of the gas passing through the combustion chamber.
Anti-adjustment means and the combustion control state determination means.
If it is determined that the baking control state, the flow resistance adjustment
Means to increase flow resistance, stoichiometric rich combustion
If the control state is determined, the flow resistance adjusting means
Flow resistance control means for reducing flow resistance by means of steps
It is characterized by. The flow resistance of the gas passing through the combustion chamber
When the drag decreases, the flow rate of the air-fuel mixture increases.
When the flow rate of the air-fuel mixture increases, the variable valve timing
Valve overlap set by the
At the very least, valve overlaps such as exhaust blowback
The effect increases. That is, the valve overlap amount
The same operation and effect as when the size is increased are exhibited. For this reason,
Switch from stoichiometric combustion control to stoichiometric rich combustion control
In this case, the flow resistance adjusting means is driven to partially
It is possible to share the adjustment of the variable valve timing mechanism.
The drive amount of the variable valve timing mechanism can be reduced.
Wear. Variable valve timing mechanism is used for oil pressure of lubricating oil, etc.
It is a mechanical adjustment mechanism driven by
The operation is slow as compared with a step or the like. So this
The amount of drive of the variable valve timing mechanism has decreased,
Responsiveness of valve overlap amount control is increased,
Control becomes possible. Further, the driving amount is reduced as described above.
Therefore, torque shock by the variable valve timing mechanism
Reduced emissions and improved emissions
And quickly move to the appropriate valve overlap
The transition period is short,
There is almost no deterioration. In addition, as the flow resistance adjusting means,
The intake side of the combustion chamber as described in claim 19
To adjust the flow resistance of
The effect of the present invention can be produced. More specifically
As the flow resistance adjusting means,
Like a swirl control valve
Can be mentioned. That is, already Swirlco
If there is a control valve, use it to flow
Resistor to function as an anti-adjusting means, the action effects described above,
Even if no new configuration is added, the software
It can be realized only by. Claim 21
As described above, the operation of the internal combustion engine is determined by the combustion control state determination means.
The rotation state changes from lean combustion control state to stoichiometric rich combustion.
When it is determined that the mode has been switched to the control state,
Start stoichiometric rich combustion control at the time of determination, and then
When the grace period Q has elapsed, the flow resistance adjusting means
Swirl control bar to reduce flow resistance
The combustion control state determining means opens the internal combustion engine.
The operating state changes from the stoichiometric rich combustion control state to the lean
If it is determined that the state has been switched to the firing control state,
The flow resistance by the flow resistance adjusting means is large when determining
Close the swirl control valve
Later, when the grace period P elapses, the lean combustion control starts
You may do it. Furthermore, as shown in claim 22
Low than the stoichiometric air-fuel ratio depending on the operating condition of the internal combustion engine.
Lean combustion control that burns with a
Burn with a mixture or a mixture richer than the stoichiometric air-fuel ratio
Internal combustion engine controller that performs stoichiometric rich combustion control
The intake valve and exhaust valve of the combustion chamber of the internal combustion engine
Variable valve that can continuously adjust the valve overlap amount
A lube timing mechanism, and at the time of the lean combustion control.
The variable valve timing corresponds to the operating state of the internal combustion engine.
Of the amount of valve overlap adjusted by the switching mechanism
First storage means for storing a pattern;
Corresponding to the operating state of the internal combustion engine during switch combustion control.
The valve adjusted by the variable valve timing mechanism.
Second storage for storing the setting pattern of the overlap amount
Means and whether the operating state of the internal combustion engine is in a lean combustion control state.
Or combustion to determine whether stoichiometric rich control
Control state determining means, and the combustion control state determining means,
It is determined that the operating state of the internal combustion engine is in the lean combustion control state
If the data is stored in the first storage means,
Based on the setting pattern of the valve overlap amount,
The variable valve timing corresponding to the operating state of the internal combustion engine
Set the valve overlap amount adjusted by the
The operating state of the internal combustion engine is changed to the stoichiometric rich combustion control state.
If it is determined that the status is the
Setting pattern of the valve overlap amount that is memorized
The variable according to the operating state of the internal combustion engine based on the
Valve overrun which is manually adjusted to the valve timing mechanism
Valve timing control means for setting the amount of
The combustion chamber is adjusted by adjusting the flow resistance on the intake side of the combustion chamber.
A means for adjusting the flow resistance of gas passing therethrough.
Flow resistance adjusting means also serving as whirl control valve
A lean combustion control state by the combustion control state determination means.
If it is determined that the flow resistance adjustment means
Increase the flow resistance, and in the stoichiometric rich combustion control state
If it is determined that there is a flow,
Flow resistance control means for reducing dynamic resistance,
In addition, the operating state of the internal combustion engine is determined by the combustion control state determining means.
From lean combustion control to stoichiometric rich combustion control
If it is determined that the state has been switched to
Stoichiometric rich combustion control is started at
When the time Q has elapsed, the flow
The swirl control valve to reduce dynamic resistance
And operating the internal combustion engine by the combustion control state determination means.
The state changes from the stoichiometric rich combustion control state to the lean combustion control state.
If it is determined that the state has been switched to
At a fixed time, the flow resistance by the flow resistance adjusting means is increased.
To close the swirl control valve
Start lean combustion control when the grace period P has elapsed
You may do it. Thus, the operating state of the internal combustion engine is
After switching to the toy-rich combustion control state,
Open the swirl control valve after the elapse of time Q
To prevent a sudden increase in the output torque of the engine,
Drivability can be maintained even better. Also internal combustion engine
The determination of the operating state of the Seki switches to the lean combustion control state
After the lapse of the grace period P, the lean combustion control is started.
Therefore, the swirl control valve is closed
Waiting for the valve overlap to decrease
It is possible to maintain better combustion stability during transient
it can.

The function of realizing each means of the internal combustion engine control device in a computer system can be provided as, for example, a program started on the computer system side. For such a program,
For example, floppy disk, magneto-optical disk, CD-
It can be used by recording it on a computer-readable recording medium such as a ROM or a hard disk, loading it into a computer system as needed, and starting up. Alternatively, the program may be recorded in a ROM or a backup RAM as a computer-readable recording medium, and the ROM or the backup RAM may be incorporated in a computer system and used.

[0050]

[First Embodiment] FIG. 1 is a schematic configuration diagram showing a gasoline engine system as a first embodiment to which the present invention is applied.

V-6 engine 10 as an internal combustion engine
Includes a cylinder block 11 in which a plurality of cylinders are formed in a V-shape when viewed in the vertical direction of the drawing, a left cylinder head 12L and a right cylinder head 12R connected to an upper portion of the cylinder block 11, respectively. A cylinder group LS and a right cylinder group RS are formed. Hereinafter, these cylinder groups will be referred to as banks. Note that the left bank LS has 2
The fourth (# 2), fourth (# 4) and sixth (# 6) cylinders belong to the right bank RS, and the first (# 1), third (# 3) and fifth (# 5) cylinders belong to the right bank RS. The cylinder belongs.

The engine 10 includes a piston 13 that reciprocates substantially vertically in each cylinder of the cylinder block 11, and a lower end of each piston 13 is connected to a crankshaft 14. By moving up and down, the crankshaft 14 is rotated.

In the vicinity of the crankshaft 14,
A crank angle sensor 40 is provided. The crank angle sensor 40 includes a magnetic rotor (not shown) connected to the crankshaft 14 and an electromagnetic pickup (not shown). Here, teeth are formed at equal angles on the outer periphery of the magnetic rotor, and a pulse-like crank angle signal is generated each time the teeth pass in front of the electromagnetic pickup.

Further, after a reference position signal is generated by a cylinder discriminating sensor 42, which will be described later, the number of generated crank angle signals from the crank angle sensor 40 is measured. 14
Is calculated (engine speed NE).

The space defined by the inner walls of each cylinder block 11, the cylinder heads 12L and 12R, and the top of the piston 13 functions as a combustion chamber 15 for burning an air-fuel mixture.
An ignition plug 16 for igniting the air-fuel mixture is disposed at the top of L and 12R so as to project into the combustion chamber 15. Distributors 18 are provided in the vicinity of the two exhaust-side camshafts 33L, 33R of the two cylinder heads 12L, 12R, respectively, and each distributor 18 is provided with the rotation of the two exhaust-side camshafts 33L, 33R. A cylinder discrimination sensor 42 for detecting a reference position signal generated at a predetermined rate is provided. The reference position signal is used for detecting the reference position of the crankshaft 14 and determining the cylinder.

Each ignition plug 16 is connected to a distributor 18 via a plug cord or the like (not shown). The high voltage output from the igniter 19 based on an ignition signal from an ECU 70 (described later) is The gas is distributed to each spark plug 16 by each distributor 18 in synchronization with the crank angle.

The cylinder block 11 is provided with a water temperature sensor 43 for detecting the temperature (cooling water temperature) THW of the cooling water flowing through the cooling water passage. further,
Each of the cylinder heads 12L and 12R has an intake port 22 and an exhaust port 32. The intake port 22 is connected to the intake passage 20, and the exhaust port 32 is connected to the exhaust passage 30. ing. An intake valve 21 is provided at each intake port 22 of the cylinder head 12, and an exhaust valve 31 is provided at each exhaust port 32.
Are arranged.

Then, each intake valve 2 of the left bank LS
A left intake camshaft 23L for opening and closing the intake valve 21 is disposed above the right bank R.
Above each intake valve 21 of S, a right intake side camshaft 23R for opening and closing the intake valve 21 is arranged. Also, each exhaust valve 31 of the left bank LS
A left-side exhaust-side camshaft 33L for opening and closing the exhaust valve 31 is disposed above the right bank RS.
Above each exhaust valve 31, a right exhaust camshaft 33R for opening and closing the exhaust valve 31 is disposed.

Further, both intake side camshafts 23L, 2
At one end of the 3R, an intake-side timing pulley 27 is provided.
Are mounted, and both exhaust side camshafts 33L, 33
An exhaust-side timing pulley 34 is attached to one end of each R. And, each timing pulley 27, 3
4 is connected to the crankshaft 14 via a timing belt 35.

Therefore, when the engine 10 is operating,
The rotational driving force is transmitted from the crankshaft 14 to the respective camshafts 23L, 23R, 33L, 33R via the timing belt 35 and the respective timing pulleys 27, 34, and the respective camshafts 23L, 23R, 33L, 33R rotate. , Each intake valve 21 and each exhaust valve 31 are driven to open and close. These valves 21 and 3
1 is the rotation of the crankshaft 14 and the piston 13
In synchronization with the vertical movement of
Engine 10 comprising an explosion / expansion stroke and an exhaust stroke
Are driven at a predetermined opening / closing timing in synchronization with a series of four strokes at

Further, both intake side camshafts 23L, 2L
In the vicinity of 3R, cam angle sensors 44L and 44R are provided, respectively.
Are provided, and each of the cam angle sensors 44L and 44R is
It is composed of a magnetic rotor (not shown) connected to both intake side camshafts 23L, 23R and an electromagnetic pickup (not shown). A plurality of teeth are formed at equal angles on the outer circumference of the magnetic rotor. For example, before the compression TDC of a predetermined cylinder, between 90 ° to 30 ° BTDC,
A pulse-like cam angle signal (displacement timing signal) accompanying the rotation of the intake camshaft 23 is detected.

Further, in the gasoline engine system according to the present embodiment, the opening / closing timing of the intake valve 21;
That is, in order to adjust the valve timing to change the valve overlap amount, the variable valve timing mechanism 50L, which is driven by hydraulic pressure, is applied to the intake timing pulley 27 of the left bank LS and the right bank RS, respectively.
50R are provided. The variable valve timing mechanisms 50L and 50R continuously change the rotation phase difference between the intake camshafts 23L and 23R with respect to the rotation of the crankshaft 14 (or the intake timing pulley 27) to continuously maintain the valve timing of the intake valve 21. This is a mechanism for changing the target (steplessly).

The two variable valve timing mechanisms 50
Oil control valves 80L, 80R (hereinafter referred to as “OCV”) corresponding to L, 50R, respectively.
Oil pumps 64L, 64R, oil filters 66L,
66R is connected. In the present embodiment, OCV8
The actuator is constituted by 0L, 80R, oil pumps 64L, 64R, and the like.

An air cleaner 24 is connected to the air intake side of the intake passage 20, and an intake air amount sensor 25 such as an air flow meter is provided downstream of the air cleaner 24, and further downstream of the intake passage is linked with an accelerator pedal (not shown). A throttle valve 26 that is driven to open and close is provided. The intake air amount is adjusted by opening and closing the throttle valve 26 by the driver's accelerator operation. Throttle valve 26
Is provided with a throttle sensor 45 for detecting the throttle opening TA.

An injector 17 for supplying fuel to the combustion chamber 15 is provided near the intake port 22 of each cylinder. Each injector 17 is an electromagnetic valve that is opened by energization, and each injector 17 is supplied with fuel pumped from a fuel pump (not shown).

Therefore, when the engine 10 is operating,
The air filtered by the air cleaner 24 is taken into the intake passage 20, and simultaneously with the intake of the air, the amount of fuel adjusted from the injectors 17 to the respective intake ports 22 is adjusted so as to achieve the required air-fuel ratio. Is injected. As a result, an air-fuel mixture having a desired air-fuel ratio is generated at the intake port 22. Then, the air-fuel mixture is sucked into the combustion chamber 15 with the opening of the intake valve 21 that is opened during the suction stroke.

The exhaust gas generated by the combustion of the air-fuel mixture in the combustion chamber 15 is discharged into the atmosphere through a catalytic converter 28 using a three-way catalyst disposed in an exhaust passage 30. An air-fuel ratio sensor 46 is arranged upstream of the catalytic converter 28, and detects the oxygen concentration of the exhaust gas for performing feedback control of the air-fuel ratio.

Further, a bypass passage 91 is provided so that the upstream side and the downstream side of the throttle valve 26 communicate with each other. An idle speed control valve (ISCV) 92 is provided in the middle of the bypass passage 91. And when idling, ISC
By adjusting the opening of the V92 by the ECU 70, the amount of intake air flowing through the bypass passage 91 is controlled, whereby the engine speed (idling speed) during idling is controlled.

Next, the variable valve timing mechanism 50L,
The system configuration of the 50R will be described with reference to FIG. For convenience of description, in FIG. 2, the variable valve timing mechanism 50L in the left bank LS and the variable valve timing mechanism 50R in the right bank RS are not distinguished from each other, and the variable valve timing mechanism 50R in the right bank RS is simply distinguished. The cross section near the camshaft 23 and the entire control system of the variable valve timing mechanism 50 are shown.

The control system of the variable valve timing mechanism 50 includes an OCV 8 for applying a driving force to the variable valve timing mechanism 50 and the variable valve timing mechanism 50.
0, based on input signals from various sensors such as a cam angle sensor 44 for detecting a cam angle signal, and a cam angle sensor 44.
An ECU 70 is provided for performing valve timing control for controlling the drive of the CV 80 to adjust the intake valve 21 to the target advance amount.

The variable valve timing mechanism 50 is disposed between the intake side camshaft 23 and the intake side timing pulley 27. The intake side camshaft 23 is rotatable between the cylinder head 12 and the bearing cap 51. It is supported by. Intake side camshaft 23
The intake side timing pulley 27 is mounted so as to be relatively rotatable in the vicinity of the end of the intake camshaft 23, and the inner cap 52 is provided with a hollow bolt 53 at the end of the intake side camshaft 23.
And a pin 54 so as to be integrally rotatable.

A housing 56 having a cap 55 is attached to the intake-side timing pulley 27 so as to be integrally rotatable by bolts 57 and pins 58. By this housing 56, the tip of the intake-side camshaft 23,
And the entire inner cap 52 is covered. Further, on the outer periphery of the intake-side timing pulley 27, a number of external teeth 27a for mounting the timing belt 35 are formed.

The intake camshaft 23 and the intake timing pulley 27 are connected by a ring gear 59 interposed between the housing 56 and the inner cap 52. The ring gear 59 has a substantially annular shape, and is housed in a space S surrounded by the intake-side timing pulley 27, the housing 56, and the inner cap 52 so as to be reciprocally movable in the axial direction of the intake-side camshaft 23. A large number of teeth 59 are provided on the inner and outer circumferences of the ring gear 59.
a, 59b are formed.

Correspondingly, a large number of teeth 52a, 52a are provided on the outer periphery of the inner cap 52 and the inner periphery of the housing 56.
56b are formed. These teeth 59a, 59b,
Both 52a and 56b are helical teeth whose tooth traces intersect with the axis of the intake-side camshaft 23 at a predetermined angle. That is, the teeth 52a and the teeth 59a mesh with each other, and the teeth 56b and the teeth 59b form a helical spline that meshes with each other.

Then, by the meshing of these, the rotation of the intake-side timing pulley 27 is rotated via the housing 56 and the inner cap 52 by the intake-side camshaft 23.
Is transmitted to Also, each tooth 59a, 59b, 52a, 5
When the ring gear 59 moves in the axial direction of the intake side camshaft 23, a twisting force is applied to the inner cap 52 and the housing 56, and the intake side camshaft 23 is attached to the intake side timing pulley 27. Move relative to

The space S has a first hydraulic chamber 60 at the distal end of the ring gear 59 for moving the ring gear 59 in the axial direction, and a second hydraulic chamber 61 at the proximal end of the ring gear 59.
have. The bearing cap 51 has a first hydraulic pressure supply hole 51a and a second hydraulic pressure supply hole 51b. In addition, a first hydraulic pressure supply hole 51 a and a first hydraulic pressure chamber 60 communicating with the first hydraulic pressure chamber 60 are provided inside the intake-side camshaft 23.
A hydraulic pressure supply path 62 and a second hydraulic pressure supply path 63 that connects the second hydraulic pressure supply hole 51b and the second hydraulic pressure chamber 61 are formed.

The lubricating oil sucked up from the oil pan 65 by the oil pump 64 is supplied to each of the hydraulic pressure supply holes 51a and 51b through the oil filter 66 at a predetermined pressure. In addition, each hydraulic supply path 62,
In order to selectively supply the hydraulic pressure to each of the hydraulic chambers 60 and 61 via the 63, each of the hydraulic pressure supply holes 51a and 51b has an OCV.
80 are connected.

The OCV 80 is a four-port directional control valve that switches the flow direction of lubricating oil by reciprocating a spool 84 in an axial direction by a plunger 83 driven by an electromagnetic actuator 81 and a coil spring 82. Then, the electromagnetic actuator 81
However, the duty is controlled to adjust the opening degree, and the magnitude of the hydraulic pressure supplied to each of the hydraulic chambers 60 and 61 is adjusted.

The casing 85 of the OCV 80 has a tank port 85t, an A port 85a, a B port 85b, and a reservoir port 85r. The tank port 85t is connected to the oil pan 6 via the oil pump 64.
A port 85a is connected to the first hydraulic supply hole 51a, and the B port 85b is connected to the second hydraulic supply hole 51b.
Is connected to The reservoir port 85r is connected to the oil pan 65.

The spool 84 is a cylindrical valve body.
It has four lands 84a for sealing the flow of the lubricating oil between the two ports, a passage 84b communicating between the two ports and allowing the flow of the lubricating oil, and two passages 84c.

In the variable valve timing mechanism 50 having these structures, the OCV 80 is driven and controlled, and when the spool 84 is moved to the left in the drawing, the passage 84b
The tank port 85t communicates with the A port 85a, and lubricating oil is supplied to the first hydraulic pressure supply hole 51a. Then, the lubricating oil supplied to the first hydraulic pressure supply hole 51 a is supplied to the first hydraulic pressure chamber 60 via the first hydraulic pressure supply path 62, and the hydraulic pressure is applied to the distal end side of the ring gear 59.

At the same time, the passage 84c communicates the B port 85b with the reservoir port 85r, and the lubricating oil in the second hydraulic chamber 61 is supplied to the second hydraulic supply passage 63, the second hydraulic supply hole 51b, and the OCV 80. Is discharged to the oil pan 65 through the B port 85b and the reservoir port 85r.

Accordingly, the ring gear 59 is moved while rotating to the base end side (right side in the drawing) by the hydraulic pressure applied to the front end side, and twist is given to the intake side camshaft 23 via the inner cap 52. . As a result, the rotational phase difference of the intake side camshaft 23 with respect to the intake side timing pulley 27 (crankshaft 14) is adjusted, and the intake side camshaft 23 is displaced from the most retarded angle to the most advanced angle. The valve opening timing of the intake valve 21 is advanced.

When the valve opening timing is advanced in this way,
The valve overlap amount, which means a period during which the intake valve 21 and the exhaust valve 31 are simultaneously opened, increases.
The movement of the ring gear 59 to the proximal end side is restricted by the ring gear 59 abutting on the intake-side timing pulley 27. When the ring gear 59 abuts on the intake-side timing pulley 27 and stops, the intake valve 21 is stopped. The valve opening timing becomes the earliest, and the valve overlap amount becomes the maximum.

On the other hand, when the drive of the OCV 80 is controlled and the spool 84 is moved rightward in the drawing, the passage 84
b communicates between the tank port 85t and the B port 85b,
Lubricating oil is supplied to the second hydraulic pressure supply hole 51b. And
The lubricating oil supplied to the second hydraulic pressure supply hole 51b is supplied to the second hydraulic pressure chamber 61 via the second hydraulic pressure supply passage 63, and the hydraulic pressure is applied to the base end side of the ring gear 59.

At the same time, the passage 84c communicates the A port 85a with the reservoir port 85r, and the lubricating oil in the first hydraulic chamber 60 is supplied to the first hydraulic supply path 62, the first hydraulic supply hole 51a, and the OCV 80. Is discharged to the oil pan 65 through the A port 85a and the reservoir port 85r.

Accordingly, the ring gear 59 is moved while rotating to the distal end side (left side in the drawing) by the hydraulic pressure applied to the proximal end side, and the intake camshaft 23 is twisted in the opposite direction via the inner cap 52. Granted. As a result,
Intake side timing pulley 27 (crankshaft 14)
, The rotational phase difference of the intake-side camshaft 23 is adjusted, the intake-side camshaft 23 is displaced from the most advanced displacement angle to the most retarded displacement angle, and the valve opening timing of the intake valve 21 is delayed. That is, the amount of advance is reduced.

Thus, by reducing the advance amount of the valve opening timing of the intake valve 21, the intake valve 21
The valve overlap amount at which the and the exhaust valve 31 are simultaneously opened is small or zero. The movement of the ring gear 59 toward the distal end is regulated by the contact of the ring gear 59 with the housing 56. When the ring gear 59 contacts the housing 56 and stops, the valve opening timing of the intake valve 21 becomes the latest. (The most retarded angle), the advance amount becomes the minimum (the valve overlap amount becomes 0).

The valve timing of the intake valve 21 changed by the variable valve timing mechanism 50 includes a cam angle signal (displacement timing signal) output from the cam angle sensor 44 and a crank angle signal output from the crank angle sensor 40. (Reference timing signal).

That is, for example, after the displacement timing signal is input to the ECU 70, the first input crank angle signal is recognized as the reference timing signal, and the reference timing signal is input after the displacement timing signal is input. Is measured using the engine speed NE. Then, the actual displacement angle VTB of the intake-side camshaft 23 with respect to the crankshaft 14 is calculated by converting the time into a displacement angle using the relationship between the known time and the crank angle.

Subsequently, the engine 10 according to the present embodiment
Will be described with reference to a control block diagram shown in FIG. The control system of the engine 10 is configured with the ECU 70 as a core. The ECU 70 performs valve timing control, air-fuel ratio control, ignition timing control, fuel injection timing control,
And a ROM 71 for storing various control programs such as control at the time of failure and a map for calculating a target value corresponding to various conditions. Also, the ECU 70
CPU 72 for executing arithmetic processing based on the control program stored in M71, RAM for temporarily storing the arithmetic results of CPU 72, data input from each sensor, and the like
73, a backup RAM 74 for holding various data stored in the RAM 73 when the power supply is stopped.

Then, the CPU 72, the ROM 71, and the RAM
73 and the backup RAM 74
5 and to the input interface 76 and the output interface 77.

The input interface 76 includes an intake air amount sensor 25, a crank angle sensor 40, a cylinder discrimination sensor 42, a water temperature sensor 43, a left cam angle sensor 44L, a right cam angle sensor 44R, a throttle sensor 45, an air-fuel ratio sensor 46, and the like. Is connected. If the signal output from each sensor is an analog signal, the signal is converted into a digital signal by an A / D converter (not shown) and then output to the bidirectional bus 75.

The output interface 77 includes an injector 17, an igniter 19, and OCVs 80L and 80.
External circuits such as R and ISCV 92 are connected, and the operation of these external circuits is controlled based on the calculation result of the control program executed by the CPU 72. The control for the variable valve timing mechanism 50L is performed by the OCV8.
The control of the variable valve timing mechanism 50R is performed by controlling the driving of the OCV 80R by controlling the driving of 0L.

Next, among the controls executed by the ECU 70, a valve timing control process by the variable valve timing mechanisms 50L and 50R performed in accordance with the air-fuel ratio control will be described with reference to a flowchart of FIG. This process is executed every predetermined crank angle cycle, for example, every 180 ° CA, or every predetermined time cycle.

Here, the ECU 70 performs the above-mentioned sensors 25, 40, 42, 43, 44 as air-fuel ratio control.
From the detection results of L, 44R, and 45, the engine speed NE
In this and other embodiments, the intake air amount GN per one revolution of the engine is used, but the throttle opening TA may be used, or the intake air amount GN or the throttle opening TA The combination of the air pressure PM may be obtained).
Based on the value of E and the engine load, based on the control switching map shown in FIG. 5, combustion at stoichiometric (stoichiometric air-fuel ratio), combustion at lean (air-fuel ratio where fuel is thinner than stoichiometric air-fuel ratio), or rich (stoichiometric air-fuel ratio) The fuel injection amount from the injector 17 is selected by selecting combustion with an air-fuel ratio richer than the fuel ratio) and feeding back or not feeding back the detection result of the air-fuel ratio sensor 46 so as to obtain the corresponding air-fuel ratio. Is set, and the fuel is injected into the intake port 22. By this air-fuel ratio control, combustion is performed at an air-fuel ratio required according to the operation state. When such air-fuel ratio control is being performed, the valve timing control process of FIG. 4 is performed. Steps in the flowchart corresponding to each process are represented by “SＳ”.

When the valve timing control process of FIG. 4 is started, first, the cooling water temperature THW of the engine 10 obtained based on the detection value of the water temperature sensor 43 is taken into the working memory (S110).

Next, the engine speed NE obtained by counting the pulses from the crank angle sensor 40 is read (S120), and the number of revolutions per revolution detected by the intake air amount sensor 25 corresponding to the engine load is read. Then, the intake air amount GN (mass) and the throttle opening TA detected by the throttle sensor 45 are read (S130).

Next, based on these detected values, it is determined whether all the lean air-fuel ratio control conditions are satisfied (S140). Here, the lean air-fuel ratio control condition is
This is a condition under which the air-fuel mixture can be burned at a lean air-fuel ratio.

(1) The relationship between the engine speed NE and the engine load falls within the stoichiometric or lean region L shown in FIG. (2) The cooling water temperature THW is sufficiently high and the warm-up is completed.

(3) The air-fuel ratio sensor 46 and other sensors are normal. (4) Throttle opening degree TA per hour or more
There is a decline. If all of these conditions are satisfied, step S1
At 40, “YES” is determined, and if at least one is not satisfied, “NO” is determined.

Under the conditions determined to be "YES" in step S140, a separate air-fuel ratio control process (not shown) simultaneously performs lean combustion control for burning with an air-fuel mixture thinner than the stoichiometric air-fuel ratio. If the determination is "NO", stoichiometric rich combustion control is also performed by air-fuel ratio control, in which combustion is performed simultaneously with a stoichiometric air-fuel mixture or an air-fuel mixture richer than the stoichiometric air-fuel ratio.

If "YES" is determined in the step S140, then the cooling water temperature THW, the engine speed NE and the engine load (the intake air amount GN or the throttle opening degree) taken in the steps S110 to S130. TA or a value obtained from the intake air amount GN and the throttle opening TA), the lean target valve timing tVTL is obtained (S150).

In order to obtain the lean target valve timing tVTL in step S150, a map shown in FIG. 6 (corresponding to the valve overlap amount setting pattern stored in the first storage means) is used. That is, this map is shown as a solid line and a contour line in FIG.
The basic target value of the amount of advance of the variable valve timing mechanisms 50L and 50R (the unit is a crank angle [゜ CA])
The engine speed NE and the engine load are set as parameters.

With respect to the basic target value obtained from this map based on the engine speed NE and the engine load,
Correction is made with the cooling water temperature THW to obtain a lean target valve timing tVTL. The correction based on the cooling water temperature THW is made such that the lean target valve timing tVTL becomes smaller as the cooling water temperature THW becomes lower in consideration of combustion stability.
This map is stored in a first map storage area of the ROM 71 (corresponding to a first storage means).

On the other hand, if "NO" is determined in the step S140, the stoichiometric rich target is then determined based on the cooling water temperature THW, the engine speed NE and the engine load taken in the steps S110 to S130. The valve timing tVTR is determined (S160).

In order to determine the stoichiometric-rich target valve timing tVTR in step S160, a map shown in FIG. 7 (corresponding to the valve overlap amount setting pattern stored in the second storage means) is used. That is, in this map, the basic target value of the advance amount of the variable valve timing mechanisms 50L and 50R is set using the engine speed NE and the engine load as parameters, as shown by solid lines and contour lines in FIG. It is.

With respect to the basic target value obtained from this map based on the engine speed NE and the engine load,
Corrected by the cooling water temperature THW as in the case of step S150, and the stoichiometric-rich target valve timing tVTR
Ask for. This map is stored in a second map storage area of the ROM 71 (corresponding to a second storage means).

Although the map shown in FIG. 7 is also shown by a broken line in FIG. 6, when comparing the two maps, the value of the map used in the lean combustion control is set to be lower as a whole. This is because the optimum valve overlap amount in the lean combustion state is smaller than the optimum valve overlap amount in the stoichiometric rich combustion control.

Step S150 or S160
Next, the lean target valve timing tVTL obtained in step S150 or the stoichiometric-rich target valve timing tVTR obtained in step S160
Is set as the final target valve timing VVT,
Drive control of the variable valve timing mechanisms 50L, 50R is performed toward the final target valve timing VVT (S170).

Thereafter, when the above-described processing is repeatedly executed at a predetermined time cycle or a predetermined crank angle cycle, and the lean combustion control is performed, the valve timing of the intake valve 21 is represented by a solid line in FIG. When the stoichiometric-rich combustion control is performed by setting a valve timing map corresponding to the lean combustion state shown in FIG. 7, the valve timing of the intake valve 21 is set to the stoichiometric combustion state and the rich state indicated by the solid line in FIG. It is set by a map of the valve timing corresponding to the combustion state.

The maps shown in FIGS. 6 and 7 show the advance amount and the valve overlap amount. Therefore, during the lean combustion control, the intake valve 21 is adjusted to a valve overlap amount suitable for the lean combustion control, and when the stoichiometric combustion control or the rich combustion control is performed, the intake valve 21 is adapted for both the stoichiometric combustion control and the rich combustion control. It will be adjusted to the overlap amount.

As described above, in the first embodiment, the setting pattern of the valve overlap amount continuously set by the variable valve timing mechanism in the lean combustion control and the stoichiometric-rich combustion control, respectively, They are stored in the map storage area and the second map storage area, respectively. Then, by the valve timing control processing, E
If the operating state of the engine 10 is in the lean combustion control state, the CU 70 controls the variable valve timing mechanisms 50L and 50L based on the map pattern of the valve overlap amount for lean combustion control stored in the first map storage area.
If the operating state of the engine 10 is in the stoichiometric-rich combustion control state, the variable valve is controlled based on the stoichiometric-rich combustion control valve overlap amount map pattern stored in the second map storage area. The timing mechanisms 50L and 50R are driven.

In the above-described processing, step S
140 corresponds to processing as combustion control state determination means,
Steps S150 and S160 correspond to processing as valve timing control means.

According to the embodiment described above, the following effects can be obtained. (I). As described above, the map for lean combustion control,
Map for stoichiometric rich combustion control and combustion chamber 1
By using the variable valve timing mechanisms 50L and 50R capable of continuously adjusting the valve overlap between the intake valve 21 and the exhaust valve 31 of the engine 5, the engine 10 can be used in both the lean combustion control and the stoichiometric-rich combustion control. The valve overlap amount can be adjusted to an optimal pattern according to the operation state.

(B). Moreover, as described in the section of “Problems to be Solved by the Invention”, the step of the valve overlap amount at the time of switching the valve overlap amount is different from the case where the control is performed by the valve overlap amount of only two stages. And the change in the torque output becomes smaller. Therefore, it is possible to prevent torque shock and achieve good drivability. Further, improvement in fuel efficiency and emission can be realized for the above-mentioned reason.

[Embodiment 2] This embodiment is different from Embodiment 1 in that a swirl control valve (abbreviated as SCV: corresponding to flow resistance adjusting means) is provided in intake port 22. The function of closing the swirl control valve under the control of the ECU 70 to generate swirl in the combustion chamber 15 and the function of opening the swirl control valve to stop the swirl are provided. As shown,
The point is that in the air-fuel ratio control process, switching between opening and closing of the swirl control valve is performed.

Further, the present embodiment is different from the first embodiment in that the map for obtaining the optimum valve overlap amount by the stoichiometric rich combustion control shown in FIG. 7 is different from the map shown in FIG. It is higher than the map for obtaining the optimum valve overlap amount in the combustion control, but is set slightly lower than the map of FIG. 7 as a whole.

As described above, the map for obtaining the optimum valve overlap amount in the stoichiometric rich combustion control is set lower than that in the first embodiment because the air-fuel ratio control process described later As shown in FIG. 9, the swirl control valve is closed in the lean combustion state, and the swirl control valve is opened in the stoichiometric rich combustion control.

That is, as shown in FIG. 10, when the swirl control valve is open, the flow resistance of the gas passing through the combustion chamber 15 decreases, so that the amount of blow-back from the combustion chamber 15 side to the intake port 22 side (internal This is because the internal EGR amount due to the valve overlap amount can be reduced from the point A in the figure to the point B by the increased amount. Therefore, in the present embodiment, the map for obtaining the optimal valve overlap amount by the stoichiometric rich combustion control is set low by the decrease from the point A to the point B.

The air-fuel ratio control process shown in FIG. 8 will be described.
At the same time, the valve timing control process of the first embodiment shown in FIG. 4 is also performed in the present embodiment. When the air-fuel ratio control process is started, first, it is determined whether all the lean air-fuel ratio control conditions are satisfied based on the values of various data that have already been captured (S220).
This lean air-fuel ratio control condition is the same as the condition described in the first embodiment.

If all the lean air-fuel ratio control conditions are satisfied ("YES" in S220), then, after all the lean air-fuel ratio control conditions are satisfied, whether or not a grace period P (time in seconds) has elapsed. Is determined (S230). If the grace period P has already elapsed, execution of the lean combustion control is set as the air-fuel ratio control (S270), and the process is temporarily terminated. By the execution setting of the lean combustion control, the amount of fuel injected from the injector 17 is adjusted so that the air-fuel mixture to the combustion chamber 15 becomes leaner than the stoichiometric air-fuel ratio in a fuel injection process (not shown). In this lean combustion control, the swirl control valve is closed.

In the state where the above-described processing is repeated and the lean combustion control is being performed, even if one of the above-described lean air-fuel ratio control conditions is not satisfied due to the driver requesting acceleration with the accelerator pedal or the like. If (S
(“NO” at 220) Next, it is determined whether or not the grace period Q (time in seconds) has elapsed after the lean air-fuel ratio control condition is not satisfied (S240).

If the grace period Q has not yet passed (S
At 240, “NO”, the swirl control valve is kept closed (S250). Then, execution of the stoichiometric rich combustion control is set as the air-fuel ratio control (S2).
80) The process is temporarily terminated. According to the execution setting of the stoichiometric rich combustion control, in a fuel injection process (not shown), the fuel amount injected from the injector 17 is adjusted such that the air-fuel mixture to the combustion chamber 15 becomes richer than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio. Is done.

If the grace period Q has elapsed while the processing of steps S220, S240, S250, and S280 is repeated while the lean air-fuel ratio control condition is not satisfied (S2
"YES" at 40), the swirl control valve is opened here (S260). Then, step S28
0, and the process ends once.

After the lean air-fuel ratio control condition is not satisfied,
The reason why the swirl control valve is opened after the elapse of the grace period Q is to prevent a sudden increase in the output torque of the engine 10 and maintain drivability. That is, immediately after the lean air-fuel ratio control condition is not satisfied, the map is switched from lean combustion control to stoichiometric rich combustion control by the processing shown in FIG. 4, and the valve overlap amount increases. When the increase in the valve overlap amount and the opening of the swirl control valve overlap, a sudden increase in the output torque of the engine 10 is caused, causing a torque shock. Therefore, a delay time of Q seconds is provided to increase the valve overlap amount. The opening timing of the swirl control valve does not overlap.

Thereafter, steps S220, S240, S2
Steps S60 and S280 are repeatedly executed. And
If all of the above-described lean air-fuel ratio control conditions come to be satisfied due to stabilization of the operating state or the like ("YES" in S220), then, after the lean air-fuel ratio control conditions are satisfied,
It is determined whether the grace time P has elapsed (S23).
0).

If the grace period P has not elapsed (S23)
0 ("NO"), the swirl control valve is closed (S250), but the stoichiometric rich combustion control continues (S280). Then, when the grace period P elapses (S2
30 ("YES"), execution of the lean combustion control is set (S270).

After the lean air-fuel ratio control condition is satisfied, the transition to the lean combustion control after the elapse of the grace period P is made by waiting until the swirl control valve is sufficiently closed and the valve overlap amount is reduced. This is to maintain combustion stability. That is, if the control is shifted to the lean combustion control while the swirl control valve is not sufficiently closed and the valve overlap amount is not small, combustion instability may be caused, and this is to be prevented.

In the above-described processing, step S
Steps 250 and S260 correspond to the processing as flow resistance control means. According to the embodiment described above, the following effects can be obtained.

(A). The same effects as (a) and (b) of the first embodiment are obtained. (B). The variable valve timing mechanism is a mechanical adjustment mechanism driven by hydraulic pressure, and operates slowly as compared with the swirl control valve. For this reason, when switching from the lean combustion control to the stoichiometric-rich combustion control, if the swirl control valve is driven to partially share the adjustment of the variable valve timing mechanism,
The drive amount of the variable valve timing mechanism can be reduced.

(C). Then, as the drive amount of the variable valve timing mechanism decreases, the responsiveness of the valve overlap amount control increases, and quick control becomes possible. (D). Further, since the driving amount is reduced in this way, the torque fluctuation due to the variable valve timing mechanism is reduced, leading to an improvement in emission. In addition, since the valve can be quickly moved to an appropriate valve overlap amount, the transition period is short, and the transition period is short. There is almost no deterioration in emissions.

(E). Also, if there is already a swirl control valve provided for swirl control, it is used to function as a flow resistance adjusting means, and the above-described operation and effect can be achieved without adding a new configuration. This can be realized only by a software change on the control side.

(F). Since the swirl control valve is opened after the elapse of the grace period Q after the lean air-fuel ratio control condition is not satisfied, a sharp increase in the output torque of the engine 10 can be prevented, and the drivability can be more favorably maintained.

(G). After the lean air-fuel ratio control condition is satisfied,
After the grace time P has elapsed, the operation shifts to lean combustion control.
It is possible to wait for the swirl control valve to close sufficiently and to reduce the valve overlap amount, so that the combustion stability during the transition can be maintained even better.

[Embodiment 3] This embodiment is different from Embodiment 1 in that air-fuel ratio control and the valve timing control processing shown in FIG. 4 are replaced with the processing in FIGS. 11, 12 and 13. The point is that the combustion fluctuation feedback control process shown is performed.

The combustion fluctuation feedback control processing shown in FIGS. 11 to 13 will be described. This processing is repeatedly executed at a predetermined cycle. First, the engine speed NE, the engine load GN, the throttle opening TA, and the cooling water temperature THW, which have already been obtained from the detection values of the sensors, are loaded into the working memory (S310).

Next, the currently acquired engine speed N
The absolute value of the difference between E (i) and the engine speed NE (i-1) taken in the previous processing is calculated and taken into the working memory (S320). Since the absolute value of the rotational speed difference reflects combustion fluctuation, the absolute value of the rotational speed difference is hereinafter referred to as “combustion fluctuation ΔNE”.

Next, it is determined whether all the lean air-fuel ratio control conditions are satisfied based on the detection values of the sensors (S330). In this determination, the same determination processing as in step S140 of the first embodiment is performed.

If all the lean air-fuel ratio control conditions are satisfied ("YES" in S330), feedback control during lean combustion is executed (S340). FIG. 12 shows the processing of the feedback control during lean combustion.

First, the lean target valve timing tVTL is set according to the engine speed NE and the engine load.
A process of obtaining from the same map as in FIG. 6 of the first embodiment and correcting with the cooling water temperature THW is performed in the same manner as in the first embodiment (S342).

Next, the combustion fluctuation ΔNE taken in step S320 is changed to the switching reference value A3 (combustion fluctuation determination value b
It is determined whether or not A3> 0) (S344). If the combustion fluctuation ΔNE> the switching reference value A3 (“YES” in S344), the rotation fluctuation air-fuel ratio rich correction rate B3 is added to the rotation fluctuation air-fuel ratio rich correction value KLLFB.
(For example, the value is set in advance in the range of 0.1 ≧ B3> 0), and is set as a new rotation fluctuation air-fuel ratio rich correction value KLLFB (S346). That is, the correction is made in the direction in which the air-fuel ratio becomes rich.

Next, the rotation fluctuation air-fuel ratio rich correction value KLL
It is determined whether or not FB is greater than an upper limit value C3 of the rotation fluctuation air-fuel ratio rich correction value (for example, a preset value is set in a range of 1.5 ≧ C3 ≧ 1.1) (S348). If the rotation fluctuation air-fuel ratio rich correction value KLLFB> the upper limit value C3 ("YES" in S348), the rotation fluctuation air-fuel ratio rich correction value KLLFB is set to the upper limit value C3 (S35).
0). Also, the rotation fluctuation air-fuel ratio rich correction value KLLFB ≦
If the upper limit value is C3 ("NO" in S348), step S350 is not executed. Accordingly, the rotation fluctuation air-fuel ratio rich correction value KLLFB is subjected to the upper limit guard at the upper limit value C3.

On the other hand, in step S344, the combustion fluctuation ΔN
If E ≦ switching reference value A3 (“N” in S344)
O ”), the rotation-variation air-fuel ratio rich correction value KLLFB is added to the rotation-variation air-fuel ratio lean correction rate D3 (for example, 0.1 ≧ D3>).
(Set in advance to a range of 0) is subtracted, and set as a new rotation fluctuation air-fuel ratio rich correction value KLLFB (S352). That is, the correction is made in the direction in which the air-fuel ratio becomes thinner.

Next, the rotation fluctuation air-fuel ratio rich correction value KLL
It is determined whether or not FB is smaller than a lower limit value E3 of the rotation fluctuation air-fuel ratio rich correction value (for example, preset in a range of 0.9 ≧ E3 ≧ 0.7) (S354). If the rotation fluctuation air-fuel ratio rich correction value KLLFB <the lower limit value E3 ("YES" in S354), the rotation fluctuation air-fuel ratio rich correction value KLLFB is set to the lower limit value E3 (S35).
6). Also, the rotation fluctuation air-fuel ratio rich correction value KLLFB ≧
If it is the lower limit value E3 ("NO" in S354), step S356 is not executed. As a result, the rotation fluctuation air-fuel ratio rich correction value KLLFB is guarded by the lower limit E3.

After the flow of processing in steps S346 to S350 or after the flow of processing in steps S352 to S356, the final lean air-fuel ratio FLEA is calculated by the following equation.
Processing for obtaining N is performed (S358).

[0147]

## EQU00001 ## Here, the basic lean air-fuel ratio tFLEAN is set in advance as a value for realizing an air-fuel ratio smaller than the stoichiometric air-fuel ratio for lean combustion control.

Next, based on the final lean air-fuel ratio FLEAN corrected by the rotation fluctuation air-fuel ratio rich correction value KLLFB in the process of step S358, lean combustion control is performed as air-fuel ratio control, as in step S270 of the first embodiment. Is set (S359), whereby the fuel injection processing separately performed by the ECU 70
The air-fuel ratio of the air-fuel mixture to the combustion chamber 15 is the final lean air-fuel ratio F
Adjusted to LEAN.

The final target valve timing VVT
The lean target valve timing tVTL obtained in step S342 is set (S360), and the variable valve timing mechanisms 50L and 50R are adjusted to reach the final target valve timing VVT (S396: FIG. 1).
1).

As described above, in the lean combustion feedback control process of step S340, when the combustion fluctuation ΔNE is larger than the switching reference value A3, the lean air-fuel ratio control corrects the air-fuel ratio in a richer direction and the combustion fluctuation ΔNE switches. When the air-fuel ratio is equal to or less than the reference value A3, the air-fuel ratio is corrected in the lean direction in the lean air-fuel ratio control. This is because, as shown in FIG. 14, the combustion fluctuation ΔNE decreases as the air-fuel ratio increases, and the combustion fluctuation ΔN decreases as the air-fuel ratio decreases.
In a range where E becomes large, and particularly in a range where the air-fuel ratio is thin, the fluctuation of the combustion fluctuation ΔNE is large. For this reason, when the lean combustion control is performed by the lean combustion feedback control process in step S340, the air-fuel ratio is feedback-corrected so that the combustion fluctuation ΔNE converges to the switching reference value A3, thereby That is, combustion fluctuations are suppressed and the air-fuel ratio is not increased more than necessary.

If at least one lean air-fuel ratio control condition is not satisfied at step S330 ("N"
O "), the stoichiometric rich combustion feedback control is executed (S370). FIG. 13 shows the processing of the feedback control during stoichiometric rich combustion.

First, the stoichiometric-rich target valve timing t is set according to the engine speed NE and the engine load.
VTR is determined from the same map as that of FIG.
Correction is made with the cooling water temperature THW as in the first embodiment (S
372).

Next, the combustion fluctuation ΔNE taken in step S320 is changed to the switching reference value F3 (combustion fluctuation determination value a
Is determined (S37).
4). The switching reference value F3 and the above-described switching reference value A3 have a relationship of 0 <F3 ≦ A3.

If the combustion fluctuation ΔNE> the switching reference value F3 (“YES” in S374), the valve timing value V
T is obtained from the stoichiometric rich valve timing tVTR and the rotation fluctuation correction valve timing displacement G obtained in step S372 as shown in the following equation (S37).
6).

[0155]

VT ← tVTR−G (i) Here, G (i) indicates the rotation variation correction valve timing displacement amount G in the current process, and is a value obtained by the following equation in step S376.

[0156]

G (i) ← G (i-1) + H3 where G (i-1) indicates the previously-determined rotation fluctuation correction valve timing displacement G, and H3 indicates the rotation fluctuation delay angle correction. Quantity (H3> 0).

As described above, in step S376, the valve timing value VT obtained by delaying G (i) from the stoichiometric rich target valve timing tVTR obtained in step S372 is obtained.

Next, it is determined whether or not the valve timing value VT obtained in step S376 is smaller than the lower limit value I3 of the valve timing value VT (S378). If the valve timing value VT <the lower limit value I3 (S378)
Is "YES"), the valve timing value VT is reduced to the lower limit value I3.
Is set (S380). If valve timing value VT ≧ lower limit value I3 (“NO” in S378), step S380 is not executed. As a result, the valve timing value VT is subjected to the lower limit guard at the lower limit I3.

On the other hand, in step S374, the combustion fluctuation ΔN
If E ≦ the switching reference value F3 (“N” in S374)
O "), the valve timing value VT is obtained from the stoichiometric-rich target valve timing tVTR and the rotation fluctuation correction valve timing displacement G obtained in step S372 as in the following equation (S382).

[0160]

VT ← tVTR + G (i) where the rotation fluctuation correction valve timing displacement amount G (i) in the current process is a value obtained by the following equation in step S382.

[0161]

G (i) ← G (i−1) −J3 Here, J3 is a rotation fluctuation advance angle correction amount (J3> 0).

As described above, in step S382, a valve timing value VT obtained by advancing G (i) from the stoichiometric-rich target valve timing tVTR obtained in step S372 is obtained.

Next, it is determined whether or not the valve timing value VT obtained in step S382 is larger than the upper limit value K3 of the valve timing value VT (S384). If the valve timing value VT> the upper limit value K3 (S384
"YES"), the valve timing value VT is increased to the upper limit value K3.
Is set (S386). If valve timing value VT ≦ upper limit value K3 (“NO” in S384), step S386 is not executed. As a result, the valve timing value VT is subjected to the upper limit guard at the upper limit value K3.

After the flow of the processing of steps S376 to 380 or after the flow of the processing of steps S382 to 386, the valve timing value VT is set to the final target valve timing VVT (S388).

Next, execution of stoichiometric rich combustion control is set as air-fuel ratio control (S390). Thus,
When the stoichiometric rich combustion feedback control process of step S370 is completed, the variable valve timing mechanisms 50L and 50R are adjusted so as to reach the final target valve timing VVT set in step S388 (S
396: FIG. 11).

As described above, in the stoichiometric rich combustion feedback control processing in step S370, when the combustion fluctuation ΔNE is larger than the switching reference value F3, the final target valve timing VVT is retarded by the processing in steps S376 to S380. If the valve overlap amount is reduced and the combustion fluctuation ΔNE is equal to or less than the switching reference value F3, steps S382 to S386 are performed.
By the process (1), the final target valve timing VVT is advanced to increase the valve overlap amount. This is because, as shown in FIG. 15, the combustion fluctuation ΔNE decreases as the valve overlap amount decreases, and the combustion fluctuation ΔNE increases as the valve overlap amount increases. In particular, in the range where the valve overlap amount is large, The fluctuation of the combustion fluctuation ΔNE is severe. Therefore, when the stoichiometric-rich combustion control is performed by the stoichiometric-rich combustion feedback control process in step S370, the valve control device performs feedback correction of the valve overlap amount to change the combustion fluctuation ΔNE to the switching reference value F3.
Therefore, the combustion fluctuation is suppressed and the valve overlap amount is not reduced more than necessary.

In the above-described processing, step S
330 corresponds to processing as combustion control state determination means,
Step S344 corresponds to processing as combustion variation determination means b, steps S346 to S358 correspond to processing as lean time correction means, step S374 corresponds to processing as combustion variation determination means a, and steps S376 to S376.
S388 corresponds to processing as stoichiometric rich correction means, and steps S342 and S372 correspond to processing as valve timing control means.

According to the embodiment described above, the following effects can be obtained. (I). The same effects as (a) and (b) of the first embodiment are obtained. (B). If the combustion fluctuation occurs during the stoichiometric rich combustion control, the valve fluctuation amount is adjusted by the variable valve timing mechanisms 50L and 50R instead of reducing the combustion fluctuation by the air-fuel ratio, which may affect the air-fuel ratio. Absent. Therefore, combustion fluctuations can be reduced without affecting the exhaust gas purification performance of the three-way catalyst of the catalytic converter 28.

(C). In the case of lean combustion control,
Since the three-way catalyst of the catalytic converter 28 is in a state where the exhaust gas purification performance cannot be exhibited, even if the air-fuel ratio is changed, the exhaust gas purification is not affected. Moreover, in the lean combustion, as shown in FIG. 16, the generation itself of NOx and the like is reduced.
Control is performed to reduce combustion fluctuations by adjusting the air-fuel ratio. As described above, according to the air-fuel ratio, unlike the adjustment by the mechanical variable valve timing mechanism, the soft control is mainly performed, so that the responsiveness is high and the combustion fluctuation can be suppressed very quickly.

(D). In the range in which the combustion fluctuation ΔNE is allowed (ΔNE ≦ A3), feedback control for approaching the optimum air-fuel ratio by returning the air-fuel ratio to a direction in which the combustion fluctuation increases, that is, to a control position where the air-fuel ratio is as lean as possible. Since the execution is performed, the fuel efficiency can be improved without excessively increasing the air-fuel ratio.

(E). In a range in which the combustion fluctuation ΔNE is allowed (ΔNE ≦ F3), feedback control is performed in a direction in which the combustion fluctuation increases, that is, by returning the valve overlap amount to a position as large as possible so as to approach the optimal valve overlap amount. As a result, the output torque and the emission can be improved without the valve overlap amount becoming excessively small.

[Embodiment 4] This embodiment is different from Embodiment 3 in that a feedback control process at the time of lean combustion shown in FIG. 12 of Embodiment 3 is shown in FIG. 17 and FIG. The point is that feedback control processing during lean combustion is performed.

In the lean combustion feedback control process of the present embodiment, first, the lean target valve timing tVTL is set according to the engine speed NE and the engine load.
Is obtained from the same map as that of FIG. 6 of the first embodiment, and a process of correcting with the cooling water temperature THW is performed in the same manner as in the first embodiment (S442).

Next, it is determined whether or not the combustion fluctuation ΔNE is larger than the lean rotation fluctuation determination value L3 (corresponding to the combustion fluctuation determination value c) (S443). Here, the magnitude relation among the switching reference value A3, the switching reference value M3 described later, and the lean rotation fluctuation determination value L3 is as shown in the following equation.

[0175]

0 <M3 <L3 <A3 Here, if ΔNE> L3 (“YE in S443”)
S "), and then the processing of steps S444 to S460 is executed. The processing in steps S444 to S460 is as follows.
This is the same process as the content of the step in FIG. 12 which is 100 less than this step number. Therefore, the combustion fluctuation Δ
When NE is larger than the switching reference value A3 ("YES" in S444), the air-fuel ratio is corrected in the lean direction in the lean air-fuel ratio control (S446), and when the combustion fluctuation ΔNE is equal to or smaller than the switching reference value A3 (S444). ("NO"), a process of correcting the air-fuel ratio in the lean direction in the lean air-fuel ratio control (S452) is performed. When the lean combustion control is performed, if ΔNE> L3, the combustion fluctuation ΔNE is converged to the switching reference value A3 by feedback-correcting the air-fuel ratio, and the combustion fluctuation ΔNE is appropriately suppressed. .

Then, when ΔNE ≦ L3 (S443)
, “NO”), and the executed process is shown in FIG. The point that the processing in FIG. 18 is performed is different from the third embodiment. First, it is determined whether the rotation variation air-fuel ratio rich correction value KLLFB is smaller than the lean / low combustion variation air-fuel ratio determination value S3 (corresponding to a concentration determination reference value) (S47).
2).

Here, if KLLFB ≧ S3 (S4
(“NO” at 72), the process jumps to step S444 in FIG. Thus, the rotation fluctuation air-fuel ratio rich correction value KLL
If FB is large, the process jumps to the process of step S444. If L3 <A3, the result of the determination in step S444 is "NO", and the process of reducing the rotation-variable air-fuel ratio rich correction value KLLFB (S452) is performed. Will be As a result, the rotation fluctuation air-fuel ratio rich correction value KL
By reducing LFB, the air-fuel ratio can be reduced.

On the other hand, if KLLFB <S3 (S47
Then, it is determined whether the combustion fluctuation ΔNE is greater than a switching reference value M3 (corresponding to a combustion fluctuation determination value d) (S474).

If the combustion fluctuation ΔNE> the switching reference value M3 (“YES” in S474), the valve timing value V
T is obtained from the lean target valve timing tVTL and the rotation fluctuation correction valve timing displacement N obtained in step S442 as in the following equation (S476).

[0180]

VT ← tVTL−N (i) Here, N (i) indicates the rotation fluctuation correction valve timing displacement amount N in the current processing, and is a value obtained by the following equation in step S476.

[0181]

N (i) ← N (i−1) + O3 where N (i−1) indicates the previously-determined rotation fluctuation correction valve timing displacement N, and O3 is the rotation fluctuation retard correction. Quantity (O3> 0).

As described above, in step S476, the lean target valve timing t obtained in step S442
A valve timing value VT obtained by delaying N (i) from VTL is obtained.

Next, it is determined whether or not the valve timing value VT obtained in step S476 is smaller than the lower limit value Q3 of the valve timing value VT (S478). If the valve timing value VT <the lower limit value Q3 (S478)
Is "YES"), and the valve timing value VT is reduced to the lower limit value Q3.
Is set (S480). If valve timing value VT ≧ lower limit value Q3 (“NO” in S478), step S480 is not executed. As a result, the valve timing value VT is subjected to the lower limit guard at the lower limit Q3.

On the other hand, in step S474, the combustion fluctuation ΔN
If E ≦ switching reference value M3 (“N” in S474)
O "), the valve timing value VT is calculated using the lean target valve timing t obtained in step S442 as in the following equation:
It is obtained from the VTL and the rotation fluctuation correction valve timing displacement amount N (S482).

[0185]

VT ← tVTL + N (i) Here, the rotation fluctuation correction valve timing displacement amount N (i) in the present process is a value obtained by the following equation in step S482.

[0186]

[Mathematical formula-see original document] N (i) <-N (i-1)-P3 Here, P3 is a rotation variation advance correction amount (P3> 0).

As described above, in step S482, the lean target valve timing t obtained in step S442
A valve timing value VT obtained by advancing N (i) from VTL is obtained.

Next, it is determined whether or not the valve timing value VT obtained in step S482 is larger than the upper limit value R3 of the valve timing value VT (S484). If the valve timing value VT> the upper limit value R3 (S484
"YES"), the valve timing value VT is increased to the upper limit value R3.
Is set (S486). If valve timing value VT ≦ upper limit value R3 (“NO” in S484), step S486 is not executed. As a result, the valve timing value VT is subjected to the upper limit guard at the upper limit value R3.

After the flow of processing in steps S476 to 480 or after the flow of processing in steps S482 to 486, the valve timing value VT is set to the final target valve timing VVT (S487).

Then, processing for setting the final lean air-fuel ratio FLEAN is performed as in the following equation (S488).

[0191]

Here, the basic lean air-fuel ratio tFLEAN is set in advance as a value for realizing an air-fuel ratio thinner than the stoichiometric air-fuel ratio for lean combustion control.

Then, after this, the final lean air-fuel ratio FLE
Based on the AN, execution of the lean combustion control is set as the air-fuel ratio control in the same manner as in step S270 of the second embodiment (S489). Accordingly, the fuel injection process separately performed by the ECU 70 causes the combustion chamber 15 Is adjusted to the final lean air-fuel ratio FLEAN.

Then, the same processing as in step S396 of FIG. 11 is performed, and the variable valve timing mechanisms 50L and 50R are adjusted so that the final target valve timing VVT is reached.

In the above-described processing, step S
443 corresponds to the processing as the combustion fluctuation determination means c, steps S444 to S458 correspond to the processing as the lean time correction means, and steps S474 to S487 correspond to the processing as the second lean time correction means, and step S472.
Corresponds to the density adjustment determining means.

According to the present embodiment described above, the following effects can be obtained. (I). The same effects as (a) to (e) of the third embodiment are obtained. (B). When the combustion fluctuation is small, the control can be performed sufficiently quickly by adjusting the small amount of valve overlap even if the response is not high. Accordingly, the determination in step S443 leads to the combustion fluctuation reduction feedback processing by adjusting the valve overlap amount in steps S474 to S487, whereby the air-fuel ratio can be maintained in a sufficiently lean state, and the fuel efficiency does not deteriorate. Further, when the combustion fluctuation is large, stable combustion can be quickly achieved by adjusting the air-fuel ratio, so that drivability is not deteriorated.

As shown in FIG. 16, although the emission and combustion fluctuation are similar even when the air-fuel ratio is adjusted, as shown in the figure, the internal EGR due to the valve overlap amount has a little less NOx and the fuel efficiency is improved. It is preferred.

(C). The combustion fluctuation ΔNE is smaller than the lean rotation fluctuation determination value L3, and the rotation fluctuation air-fuel ratio rich correction value KLLFB is equal to the lean / low combustion fluctuation air-fuel ratio determination value S3.
If it is larger ("NO" in S472), the process of reducing the combustion fluctuation ΔNE by adjusting the air-fuel ratio (step S472).
444-S456). This allows
Since the process of step S452 is performed, as a result, instead of increasing the valve overlap amount, the air-fuel ratio can be made as lean as possible, and the fuel efficiency can be further improved.

[Embodiment 5] This embodiment is different from Embodiment 3 in that feedback control during lean combustion shown in FIG. 12 of Embodiment 3 is shown in FIGS. 19 and 20. The point is that feedback control processing during lean combustion is performed.

Further, the ECU 70 controls the path of the lubricating oil, for example, the oil pan 65 or the oil pump 64L,
The third embodiment differs from the third embodiment in that an oil temperature sensor as a hydraulic fluid temperature detecting means is provided in an oil passage or the like from the 64R to the variable valve timing mechanisms 50L and 50R, and the oil temperature is detected via the input interface 76. Is different.

In the lean combustion feedback control process of the present embodiment, first, the lean target valve timing tVTL is set according to the engine speed NE and the engine load.
Is obtained from the same map as that in FIG. 6 of the first embodiment, and a process of correcting with the cooling water temperature THW is performed in the same manner as in the first embodiment (S542).

Next, it is determined whether or not the engine speed NE is smaller than the responsiveness determining speed T3 (corresponding to the determining speed) (S543). Here, if NE <T3 (“YES” in S543), then steps S544 to S544
The process of 560 is executed. These steps S544-
The process of S560 is the same as the content of the step in FIG. 12 that is 200 less than this step number. Therefore, when the combustion fluctuation ΔNE is larger than the switching reference value A3, the air-fuel ratio is corrected in the lean direction in the lean air-fuel ratio control, and when the combustion fluctuation ΔNE is less than the switching reference value A3, the air-fuel ratio is reduced in the lean air-fuel ratio control. Is performed. When the lean combustion control is performed, if NE <T3, the combustion fluctuation ΔNE is converged to the switching reference value A3 by feedback-correcting the air-fuel ratio, and the combustion fluctuation ΔNE is appropriately suppressed. .

Then, when NE ≧ T3 (“NO” in S543), the processing executed is shown in FIG. First, it is determined whether or not the oil temperature of the lubricating oil (corresponding to the working fluid) of the engine 10 is higher than the responsiveness determination lower-side oil temperature U (S570). If the oil temperature is higher than the responsiveness determination lower-side oil temperature U ("YES" in S570), it is next determined whether the oil temperature is lower than the responsiveness determination higher-side oil temperature V (S570).
571). If the oil temperature is lower than the responsiveness determination high-temperature side oil temperature V ("YES" in S571), it is next determined whether the rotation fluctuation air-fuel ratio rich correction value KLLFB is smaller than the lean / low combustion fluctuation air-fuel ratio determination value S3. A determination is made (S572).

Here, when the oil temperature is equal to or lower than the responsiveness judgment low temperature side oil temperature U ("NO" in S570), when the oil temperature is equal to or higher than the responsiveness judgment high temperature side oil temperature V ("NO" in S571), Alternatively, if KLLFB ≧ S3 (“NO” in S572),
The process jumps to step S544 in FIG. Step S
The processing performed in steps 544 to S560 is the same as the processing in steps S344 to S360 shown in FIG. 12 in the third embodiment, and performs feedback control for suppressing the combustion fluctuation ΔNE by adjusting the air-fuel ratio.

When the oil temperature is equal to or lower than the responsiveness judgment low-temperature side oil temperature U ("NO" in S570), the feedback control process (steps S544 to S558) for suppressing the combustion fluctuation ΔNE by adjusting the air-fuel ratio is performed. Figure 2
As shown in FIG. 1B, when the oil temperature is lower than U or lower, the friction in the variable valve timing mechanisms 50L, 50R increases, so that the variable valve timing mechanisms 50L, 5R are increased.
This is because the operation at 0R becomes slow, and the responsiveness of the valve overlap amount adjustment is deteriorated, so that the combustion stability cannot be quickly restored. In order to improve the responsiveness, the execution of the valve overlap amount adjustment processing in steps S574 to 587 is prohibited, and the combustion fluctuation ΔNE is suppressed by adjusting the air-fuel ratio (steps S544 to S558).
It shifts to.

When the oil temperature is equal to or higher than the responsiveness judgment high temperature side oil temperature V ("NO" in S571), the flow shifts to feedback control processing (steps S544 to S558) for suppressing the combustion fluctuation ΔNE by adjusting the air-fuel ratio. What is done in Figure 21
As shown in (b), on the high side where the oil temperature is higher than V, the leakage in the lubricating oil path increases and the hydraulic pressure decreases, which causes the variable valve timing mechanisms 50L and 50R.
This is because the operation becomes slow, and the responsiveness of the valve overlap amount adjustment deteriorates, so that the combustion stability cannot be quickly restored. In order to improve the responsiveness, the execution of the valve overlap amount adjustment processing in steps S574 to 587 is prohibited, and the process shifts to the combustion fluctuation ΔNE suppression processing by adjusting the air-fuel ratio (steps S544 to S558). is there.

Note that the rotation fluctuation air-fuel ratio rich correction value KLL
When FB is equal to or more than S3 ("N" in S572
O ”), the process jumps to step S544 in step S472 in the fourth embodiment.
For the same reason as jumping to 44.

Steps S572 to S589 are the same as steps S472 to S489 of the fourth embodiment. In the above-described processing, step S543 corresponds to the processing as the internal combustion engine rotation speed determining means,
Steps 570 and S571 correspond to processing as hydraulic fluid temperature determination means, steps S544 to S558 correspond to processing as lean time correction means, and steps S574 to S587 correspond to processing as third lean time correction means. It is determined as “NO” in either of steps S570 and S571, execution of the valve overlap amount adjustment processing in steps S574 to 587 is prohibited, and step S544 is performed.
The processing of jumping to the subsequent processing corresponds to the processing as the correction prohibiting means.

According to the present embodiment described above, the following effects can be obtained. (I). The same effects as (a) to (e) of the third embodiment are obtained. (B). On the high rotation side, the valve overlap amount is adjusted based on the rotation speed NE of the engine 10 (S574 to S574).
587) to reduce the combustion fluctuation, and on the low rotation speed side, the combustion fluctuation is reduced by adjusting the air-fuel ratio (S544 to S558). The adjustment of the valve overlap amount is advantageous for both fuel consumption and emission, but when the internal combustion engine is running at a low speed, the variable valve timing mechanisms 50L, 50L
Since the response of 0R is poor, the air-fuel ratio is adjusted on the low rotation speed side. However, since the responsiveness of the variable valve timing mechanisms 50L and 50R is improved on the high rotation side, combustion fluctuation is reduced by adjusting the valve overlap amount. Therefore, while suppressing combustion fluctuation quickly,
We can strive to improve fuel economy and emissions as much as possible.

(C). If the oil temperature is out of the allowable temperature range between the responsiveness determination low-temperature side oil temperature U and the responsiveness determination high-side oil temperature V, the suppression of combustion fluctuations is suppressed even at the high rotation side. It depends on the adjustment. As a result, the friction increases at a low temperature, or the oil pressure decreases due to a leakage of lubricating oil at a high temperature, so that the variable valve timing mechanism 50L,
Even if the responsiveness of the 50R is deteriorated, the variable valve timing mechanisms 50L and 50R are not driven, so that it is possible to prevent instability of the combustion, deterioration of the fuel consumption and emission.

(D). When the engine speed NE is equal to or higher than the responsiveness determination rotation speed T3, the oil temperature is higher than the responsiveness determination lower oil temperature U and lower than the responsiveness determination higher oil temperature V (corresponding to an allowable temperature range), and The rotation variation air-fuel ratio rich correction value KLLFB is equal to the lean / low combustion variation air-fuel ratio determination value S3.
If it is larger ("NO" in S572), the process of reducing the combustion fluctuation ΔNE by adjusting the air-fuel ratio (Step S
544-S556). This allows
Since the processing of steps S552 to S556 is started,
As a result, instead of increasing the valve overlap amount, the air-fuel ratio can be made as lean as possible,
The same effect as (c) of the fourth embodiment is obtained in that fuel efficiency can be further improved.

[Sixth Embodiment] The present embodiment is different from the first embodiment in that valve timing control shown in FIG. 22 is executed instead of the valve timing control shown in FIG. 4 of the first embodiment. It is a point that is done. Note that the valve timing control of FIG. 22 is repeatedly executed at a predetermined time period.

When the valve timing control shown in FIG. 22 is started, first, the engine speed N obtained by counting the pulses from the crank angle sensor 40 is calculated.
E, engine load (here, for example, the intake air amount GN per one rotation detected by the intake air amount sensor 25,
As described in the first embodiment, the throttle opening TA may be used or combined in some cases, or the intake air pressure PM may be combined as described in the first embodiment).
Of the engine 10 determined based on the throttle opening TA detected by the engine and the value detected by the water temperature sensor 43
Of the cooling water temperature THW in the working memory (S61)
0).

Next, based on these detected values, it is determined whether all the lean air-fuel ratio control conditions are satisfied (S640). This processing is performed in step S of the first embodiment.
This is the same process as 140, and it is determined whether all of the conditions (1) to (4) described in the first embodiment are satisfied.

When all of these conditions (1) to (4) are satisfied, the determination is "YES" in step S640, and when at least one is not satisfied, the determination is "NO".

[0215] Under the condition determined as "YES" in step S640, the lean combustion control is performed by a separate air-fuel ratio control process (not shown). The stoichiometric rich combustion control is performed by the air-fuel ratio control.

If "YES" is determined in the step S640, the engine speed NE, the engine load and the cooling water temperature TH taken in the step S610 are determined.
Based on W, a lean target valve timing tVTL is determined (S650). In order to determine the lean target valve timing tVTL, the same map as that shown in FIG. 6 of the first embodiment is used, and similarly, the lean target valve timing tVTL is corrected by the coolant temperature THW.
VTL is required.

Next, the value of the lean target valve timing tVTL is set to the valve timing value VT (S65).
2), the gradual change end flag XVT is cleared (S65)
4). Then, the valve timing value VT is set to the final target valve timing VVT, and the variable valve timing mechanism 50 is moved toward the final target valve timing VVT.
Drive control of L and 50R is performed (S670). As a result, the valve timing of the intake valve 21 becomes
Are set in accordance with the map of the valve timing corresponding to the lean combustion state shown in FIG.

On the other hand, if "NO" is determined in the step S640, then, based on the engine speed NE, the engine load and the coolant temperature THW taken in the step S610, the stoichiometric-rich target valve timing is determined. tVTR is determined (S660).

Stoichiometric rich target valve timing t
In order to obtain the VTR, the same map as that shown in FIG. 7 of the first embodiment is used.
The stoichiometric-rich target valve timing tVTR is obtained after being corrected by HW.

Next, it is determined whether or not the gradual change end flag XVT is in the clear state (0) (S662). If the gradual change end flag XVT = 0 (“YE
S "), the throttle opening change, which is a value obtained by subtracting the throttle opening TA previously read in step S610 from the throttle opening TA read in step S610 this time. It is determined whether the amount ΔTA is smaller than the acceleration determination throttle opening speed W3 (W3> 0: corresponding to an acceleration request determination value) (S6).
63). In this determination, since the intake of the throttle opening TA in step S610 is performed in a time cycle, the degree of the opening speed of the throttle opening TA is checked to determine whether the driver's request is a slow acceleration request or a sudden acceleration request. This is to determine whether the request is for acceleration.

If the acceleration is moderate, that is, if ΔTA <W3 (“YES” in S663), the valve timing value VT
Is calculated as in the following equation (S664).

[0222]

VT ← tVTL + X where X is the variable valve timing mechanism 50L, 50R.
Is a gradual change value for gradually changing the valve timing from the lean target valve timing tVTL to the stoichiometric-rich target valve timing tVTR, and is a value determined corresponding to one cycle time of the present control (゜ CA).

Next, it is determined whether or not the valve timing value VT calculated in step S664 is smaller than the stoichiometric-rich target valve timing tVTR calculated in step S660 (S665).

If VT <tVTR ("Y" in S665)
ES "), since the gradual change should be continued, the process immediately proceeds to step S670, and the valve timing value VT calculated in step S664 is changed to the final target valve timing V.
VT is set.

Thereafter, as long as the slow acceleration request continues, the valve overlap amount gradually increases in accordance with the valve timing value VT increased by the gradual change value X in the calculation of step S664.

While repeating this process, ΔTA ≧
If W3 and the request for rapid acceleration is made ("NO" in S663), or if the valve timing value VT that has been gradually increased catches up with the stoichiometric-rich target valve timing tVTR and VT ≧ tVTR ( If “NO” in S665), the gradual change end flag XVT is set (XVT ← 1) (S666).

Alternatively, even when a sudden acceleration request (ΔTA ≧ W3) is made (“NO” in S663) from the beginning of the determination of “NO” in step S640, the gradual change end flag XVT is set (XVT ←). 1) is performed (S666).

Then, the value of the stoichiometric-rich target valve timing tVTR is set to the valve timing value VT (S667), and the valve timing value VT is set to the final target valve timing VVT, and is variable toward the final target valve timing VVT. Valve timing mechanism 5
The drive control of 0L and 50R is performed (S670).

Therefore, in the next control cycle, XVT =
Since it is 1 ("NO" in S662), the value of the stoichiometric-rich target valve timing tVTR is immediately set to the valve timing value VT (S667), and the valve timing value VT is set to the final target valve timing VVT. Drive control of the variable valve timing mechanisms 50L and 50R is performed toward the final target valve timing VVT (S670). That is, the gradual change processing ends, and the normal valve timing control processing at the time of the stoichiometric rich combustion control is performed.

In the processing described above, the throttle sensor 45 corresponds to the acceleration request detecting means, and step S6
Step 64 corresponds to the processing as the gradual change means.
3 corresponds to the processing as the gradual change inhibiting means.

(A). The same effects as (a) and (b) of the first embodiment are obtained. (B). When switching the valve timing map from the valve timing map corresponding to the lean combustion state to the valve timing map corresponding to the stoichiometric combustion state and the rich combustion state, instead of switching all at once, gradually switching by a gradual change process. Thus, the sudden change and increase in the output torque are moderated.

Therefore, as shown in the timing chart of FIG. 23, when the gradual change process in step S664 is not performed, the enrichment of the air-fuel ratio and the increase of the valve overlap amount are synergistically increased as indicated by the dashed line. However, in the present embodiment, as shown by the solid line, the valve overlap amount gradually increases, so that the torque rise is moderated and the torque shock is sufficiently increased. And drivability can be further improved.

(C). In addition, if there is a sudden acceleration request ("NO" in S663), the gradual change process is immediately stopped, and the value of the stoichiometric-rich target valve timing tVTR is used as it is. Can be.

When the driver is requesting rapid acceleration, even if the torque increases rapidly, the driver does not feel a torque shock but feels good acceleration, but in this case, on the contrary, it gradually increases. It feels that increasing the torque at the same time decreases the acceleration response. For this reason, at the time of rapid acceleration, it is prohibited to gradually change the set pattern, and it is possible to switch at once to allow a rapid increase in torque. Thereby, good drivability can be maintained.

[Other Embodiments] In the above embodiments, the valve overlap amount was changed by adjusting the advance amount of the intake valve, but the valve overlap amount by the intake valve was changed. Instead of the adjustment, a variable valve timing mechanism may be provided on the exhaust camshaft to adjust the valve overlap amount by adjusting the exhaust valve side retard amount. Alternatively, in addition to adjusting the valve overlap amount based on the advance amount of the intake valve, the retard amount is also adjusted on the exhaust valve side, so that the intake valve and the exhaust valve cooperate to reduce the valve overlap amount. Adjustments may be made.

In each of the above embodiments, the variable valve timing mechanisms 50L and 50R are provided with helical spline mechanisms, and the ring gear 59 moves in the direction of the rotation axis, so that the intake side camshaft 23 The rotation phase difference is adjusted by rotating the camshaft relative to the crankshaft.In addition, the vane provided on the camshaft rotates around the rotation axis, so that the camshaft moves relative to the crankshaft. A vane type in which the rotational phase difference is adjusted by rotating relative to each other may be used. Alternatively, the valve timing may be adjusted by moving the three-dimensional cam provided on the camshaft in the axial direction of the camshaft. Further, a combination of these configurations may be used.

The differences of the above embodiments may be combined. For example, with Embodiments 1, 2, or 6,
Combination with Embodiments 3, 4 and 5 or Embodiment 2
And Embodiment 6 may be combined, or Embodiment 4 and Embodiment 5 may be combined.

In each of the above embodiments, the maps shown in FIGS. 6 and 7 are represented by the advance amount of the intake valve, but may be represented directly by the valve overlap amount. If the retard amount of the intake valve or the rotational phase difference of the exhaust valve can be adjusted, it may be represented by the advance amount or retard amount of the exhaust valve. That is, the map does not need to be directly represented by the valve overlap amount, but may be represented by the advance amount and the retard amount of the intake valve and the exhaust valve, and corresponds to the valve overlap amount. If it is a physical quantity, it can be used as a setting pattern of the valve overlap amount.

In the case of an engine having a plurality of intake valves, instead of the swirl control valve of the second embodiment, in the case of an engine having a plurality of intake valves, a means for controlling the opening and closing of some intake valves may be mentioned. be able to. Also, a case where a plurality of exhaust valves are provided can be similarly mentioned as a flow resistance adjusting means.

In the third embodiment, in the stoichiometric rich combustion control, the combustion fluctuation is reduced by adjusting the valve overlap amount, and in the lean combustion control, the combustion fluctuation is reduced by adjusting the air-fuel ratio. If the responsiveness of the valve overlap amount does not matter, the combustion fluctuation may be reduced by adjusting the valve overlap amount in both the stoichiometric rich combustion control and the lean combustion control. Even in this case, as shown in FIG.
There is no problem because the combustion fluctuation and the NOx generation amount show the same tendency as the air-fuel ratio adjustment in the lean combustion.

In the fourth embodiment, if it is not particularly necessary to make the air-fuel ratio as lean as possible, step S472
Is not provided, and the rotation-variation air-fuel ratio rich correction value K
Even when the LLFB is larger than the lean / low combustion fluctuation air-fuel ratio determination value S3, it may be dealt with by increasing the valve overlap amount. Step S of Embodiment 5
The same applies to 572.

In the fifth embodiment, the responsiveness of the variable valve timing mechanisms 50L and 50R is determined based on the oil temperature of the engine 10 because the variable valve timing mechanisms 50L and 50R are driven by hydraulic pressure. As a physical quantity corresponding to the oil temperature, for example, using the value of the cooling water temperature THW,
The determination may be made indirectly by detecting the oil temperature. in this case,
The oil temperature sensor does not need to be specially provided.

In the fifth embodiment, when the oil temperature is not within the allowable range (U to V), the combustion fluctuation ΔNE reduction process is performed by adjusting the air-fuel ratio.
If not, the combustion variation ΔNE reduction process based on the valve overlap amount may simply be prohibited.

Step S57 in the fifth embodiment
0, the oil temperature determination process of S571 is omitted, and instead, the value of the responsiveness determination rotation speed T3 used in step S543 is varied depending on the oil temperature, so that the oil temperature falls within the allowable range (U to V). If not, in step S543, “YE
S "may be easily determined to make it difficult to perform the combustion fluctuation ΔNE reduction process (S574 to S589) due to the valve overlap amount. For example, if the oil temperature is within the allowable range (U to
V), it can be realized by increasing the value of the responsiveness determination rotation speed T3 as compared with the case where the speed is in the allowable range (U to V).

When there is no problem of oil leakage due to the clearance of the lubricating oil path, the value of the responsiveness determination rotation speed T3 is simply reduced in response to the increase in the oil temperature, and the response is determined in response to the decrease in the oil temperature. When the friction is high at a low temperature by increasing the value of the gender determination rotation speed T3, the combustion fluctuation ΔNE reduction process due to the valve overlap amount (S574 to S574)
S589) may not be performed.

Step S57 in the fifth embodiment
0, the oil temperature determination process in S571 is omitted, and step S54 is performed.
3, the combustion fluctuation ΔNE is determined only by the determination of the engine speed NE.
May be determined depending on the air-fuel ratio or the valve overlap amount.

In the third to fifth embodiments, the fluctuation of the engine speed is used as the combustion fluctuation ΔNE. Other than this, the fluctuation of the combustion pressure in the combustion chamber detected by the combustion pressure sensor or the acceleration sensor The fluctuation of the engine vibration to be captured may be used as the combustion fluctuation ΔNE.

Although the embodiments of the present invention have been described above, the embodiments of the present invention include the following various technical items in addition to the technical items described in the claims. It should be noted that it has.

(1). In the internal combustion engine control device according to any one of claims 1 to 17 , the correction of the air-fuel ratio in the direction in which the combustion fluctuation is reduced is performed by correcting the air-fuel ratio to the rich side, and the direction in which the combustion fluctuation is increased. The correction of the air-fuel ratio is performed by correcting the air-fuel ratio to the lean side, and the correction of the valve overlap amount in the direction in which the combustion fluctuation is reduced is performed by reducing and correcting the valve overlap amount. An internal combustion engine control device according to claim 1, wherein the correction of the valve overlap amount in the direction in which the combustion fluctuation increases is performed by increasing and correcting the valve overlap amount.

(2). The allowable temperature range of claim 1 1 or 1 2, the control apparatus for an internal combustion engine wherein the variable friction of the valve timing mechanism is not high, and leakage of the working fluid is less temperature range.

(3). A computer-readable recording medium storing a program for causing a computer system to function as each means of the internal combustion engine control device according to any one of claims 1 to 22 .

[0252]

According to the first aspect of the present invention, the internal combustion engine control system sets the first valve overlap amount setting pattern that is continuously set by the variable valve timing mechanism in the lean combustion control and the stoichiometric rich combustion control. It is stored in the storage means and the second storage means. When the operating state of the internal combustion engine is in the lean combustion control state, the valve timing control means controls the variable valve timing mechanism based on the set pattern of the valve overlap amount for lean combustion control stored in the first storage means. If the operating state of the internal combustion engine is the stoichiometric rich combustion control state, the variable valve timing mechanism is controlled based on the stoichiometric rich combustion control valve overlap amount setting pattern stored in the second storage means. Drive.

As described above, by using the variable valve timing mechanism capable of continuously adjusting the valve overlap between the intake valve and the exhaust valve of the combustion chamber, the lean combustion control and the stoichiometric-rich combustion control can be performed. The valve overlap amount can be adjusted to an optimal pattern according to the operation state of the internal combustion engine.

Therefore, as described in the section “Problems to be Solved by the Invention”, the above set patterns are compared with those for the lean combustion control and those for the stoichiometric control as compared with the case where the control is performed with the valve overlap amount of only two stages. -When switching for rich combustion control, the step of the valve overlap amount at the time of switching the valve overlap amount is small, and the change in torque output is correspondingly small. Therefore, good drivability can be realized by preventing torque shock. Further, improvement in fuel efficiency and emission can be realized for the above-mentioned reason. Also, stoichiometric rich combustion system
If combustion fluctuations occur during operation, the combustion fluctuations depend on the air-fuel ratio.
Variable valve timing mechanism, instead of reducing movement
Adjusts the amount of valve overlap by the air-fuel ratio
Has no effect. Therefore, three-way catalyst
Reduce combustion fluctuations without affecting exhaust gas purification performance
Can be frustrated.

[0255]

[0256]

[0257]

[0258]

[0259]

[0260]

[0261] Claim 2 is the stoichiometric - as rich time correcting means, the combustion variation is fed back controlling the valve overlap amount to converge to the combustion variation determining value a, unnecessarily valve overlap amount Can be suppressed without compensating for the combustion fluctuation.

In the third and fourth aspects, the lean correction means determines that the lean combustion control is being performed by the combustion control state determination means, and the combustion fluctuation determination means b determines the combustion fluctuation. When it is determined that the air-fuel ratio is larger than the value b, the air-fuel ratio of the air-fuel mixture is corrected in a direction in which the combustion fluctuation is reduced, so that the combustion fluctuation can be suppressed very quickly.

That is, in the case of the lean combustion control, the exhaust gas purification performance is already in a state where it cannot be exhibited, so that even if the air-fuel ratio is changed, the exhaust gas purification is not affected. Moreover, since lean combustion reduces the generation of NOx and the like,
The air-fuel ratio of the air-fuel mixture is controlled to reduce combustion fluctuations. In this way, if the combustion fluctuation is suppressed by adjusting the air-fuel ratio, unlike the adjustment by the mechanical variable valve timing mechanism, the soft control is the main, so the response is high and the combustion fluctuation is suppressed very quickly. be able to.

According to a fifth aspect of the present invention, the lean-time correction means feedback-controls the air-fuel ratio of the air-fuel mixture so that the combustion fluctuation converges on the combustion fluctuation determination value b. It is possible to suppress the combustion fluctuation without causing.

According to a sixth aspect of the present invention, the combustion control state determining means determines that the lean combustion control is being performed, and the combustion fluctuation determining means c determines that the combustion fluctuation is larger than the combustion fluctuation determining value c. In this case, the lean time correction means is made to function, the combustion control state determination means determines that the lean combustion control is being performed, and the combustion fluctuation determination means c determines that the combustion fluctuation is the combustion fluctuation determination value c. If it is determined that the air-fuel ratio is smaller than the air-fuel ratio, the second lean-time correction means is operated. By adjusting the valve overlap amount, the combustion fluctuation can be suppressed sufficiently quickly. For this reason, the air-fuel ratio can be maintained in a sufficiently lean state, and the fuel consumption does not deteriorate. Also,
When the combustion fluctuation is large, stable combustion can be achieved early by adjusting the air-fuel ratio, so that drivability is not deteriorated.

[0266] According to claim 7, as the second lean time correction means, the combustion fluctuation feedback control of the valve overlap amount to converge to a combustion variation determining value d, unnecessarily corrected valve overlap amount The combustion fluctuation can be suppressed without performing.

In the eighth aspect , the combustion control state determining means determines that the lean combustion control is being performed, and the combustion variation determining means c determines that the combustion variation is smaller than the combustion variation determination value c. In this case, when it is determined that the correction of the air-fuel ratio of the mixture is adjusted to a mixture richer than a concentration determination reference value by the concentration adjustment determination unit, the second lean time correction unit is activated. Instead, the lean time correction means is made to function, so that fuel efficiency can be further improved.

That is, when the combustion fluctuation is smaller than the combustion fluctuation judgment value c and the air-fuel mixture is corrected to an air-fuel mixture richer than the concentration judgment reference value, the above-mentioned lean correction means can be used to operate the combustion fluctuation. Can be returned to a direction in which the combustion fluctuations increase in a range in which the air-fuel ratio becomes as lean as possible, that is, a control position where the air-fuel ratio becomes as lean as possible. As a result, instead of increasing the valve overlap amount, the air-fuel ratio can be made as lean as possible, and the fuel efficiency can be further improved.

In the ninth aspect , even during the lean combustion control, the combustion fluctuation is suppressed by adjusting the valve overlap amount on the high rotation side based on the rotation speed of the internal combustion engine, and the air-fuel ratio on the low rotation side is controlled. Combustion fluctuation is suppressed by adjustment.

According to the adjustment of the valve overlap amount,
Although it is advantageous for both fuel consumption and emission, when the internal combustion engine is running at low speed, the variable valve timing mechanism is slow to drive and the response is poor, so in lean combustion control, the combustion fluctuation is suppressed by adjusting the air-fuel ratio on the low speed side. are doing. However, on the high rotation side, the variable valve timing mechanism is driven quickly and has good responsiveness, so that it does not affect combustion stability and does not deteriorate drivability. Combustion fluctuation is suppressed by adjustment. Therefore, combustion fluctuations can be quickly suppressed regardless of the rotational speed of the internal combustion engine, and efforts can be made to improve fuel economy and emissions as much as possible.

[0271] Claim 1 0, as the third lean time correction means, the combustion fluctuation feedback control of the valve overlap amount to converge to a combustion variation determining value e, unnecessarily the valve overlap amount Combustion fluctuations can be suppressed without correction.

[0272] Claim 1 1, wherein at hydraulic fluid temperature determining means, when said temperature of the hydraulic fluid is determined not to exist in the allowable temperature range, the second lean time correcting means or said third lean Since the function of the time correction means is prohibited, unstable combustion, deterioration of fuel efficiency and emission can be prevented.

If the working fluid such as lubricating oil is at a low temperature, the friction increases, and if the working fluid is at a high temperature, the hydraulic pressure drops due to fluid leakage, and the driving of the variable valve timing mechanism becomes slower, and the valve overlap amount is adjusted. Responsiveness is reduced. Therefore, when the temperature is outside the allowable temperature range, the suppression of combustion fluctuation by correcting the valve overlap amount is prohibited. This can prevent unstable combustion and deterioration of fuel efficiency and emission.

[0274] Claim 1 2, wherein at hydraulic fluid temperature determining means, when said temperature of the hydraulic fluid is determined not to exist in the allowable temperature range, the second lean time correcting means or said third lean The time correction means is prohibited from functioning, and the lean time correction means is functioned. Therefore, when it is inappropriate to adjust the valve overlap amount due to the temperature of the hydraulic fluid, the air-fuel mixture The combustion fluctuation can be suppressed at the air-fuel ratio of, and stable combustion can be maintained.

According to claims 13 and 14 , when switching from the setting pattern stored in the first storage means to the setting pattern stored in the second storage means, the switching is not performed at once, but is performed gradually. This makes it possible to moderate the sudden change and increase in the output torque, thereby preventing torque shock and further improving drivability.

[0276] Claim 1 5, when a large acceleration demand is so as not to function the gradual change means.
That is, when sudden acceleration is required by the driver's operation, the switching of the set pattern is stopped gradually, and a sudden change of the set pattern is allowed to respond to the driver's request.

When the driver is requesting rapid acceleration, even if the torque increases rapidly, the driver does not feel a torque shock but feels good acceleration, and conversely, gradually increases the torque. The driver feels that the acceleration responsiveness is degraded, so that at the time of rapid acceleration, it is prohibited to gradually switch the set pattern, and good drivability is maintained.

The sixteenth and seventeenth aspects of the present invention relate to a setting pattern of a valve overlap amount stored in the first storage means and the second storage means, wherein a load of the internal combustion engine and a rotational speed of the internal combustion engine are used as parameters. Since this is realized as a map of the valve overlap amount, the valve overlap amount can be precisely adjusted according to the operating state. Claim
Item 18. The internal combustion engine control device according to Item 18, wherein the flow resistance control
Means for controlling the lean combustion control by the combustion control state determining means.
The flow resistance adjusting means if it is determined that the
To increase flow resistance and control stoichiometric rich combustion
If determined to be in the state, the flow resistance adjusting means
Make the flow resistance smaller. Thus, passing through the combustion chamber
When the flow resistance of the gas mixture decreases,
The flow velocity increases. When the flow rate of the mixture increases,
Valve valve set by the variable valve timing mechanism
Even if the amount of burlap is small,
The effect of the overlap increases. That is, valve
-Has the same effect as increasing the amount of burlap
You. For this reason, stoichiometric-rich fuel
When switching to baking control, this flow resistance adjustment means
Drive to partially adjust the variable valve timing mechanism
If shared, the drive amount of the variable valve timing mechanism will be small.
Can be eliminated. Variable valve timing mechanism
A mechanical adjustment mechanism driven by the oil pressure of lubrication oil, etc.
Operation is slower than flow resistance adjustment
You. Therefore, the driving of this variable valve timing mechanism
The amount of valve overlap control
Responsiveness is improved, and quick control becomes possible. Furthermore, this
Variable valve timing machine
Torque shock due to
Of the valve
The transition period is short because it can move to the burlap amount.
There is almost no deterioration in emissions. Claim 19
Is provided on the intake side of the combustion chamber as the flow resistance adjusting means.
Use the one that adjusts the flow resistance to produce the above-mentioned effects.
Can be 20. The method of claim 19, further comprising:
Resistance adjustment means also serves as swirl control valve
Therefore, use the existing swirl control valve.
To function as flow resistance adjusting means, as described above.
The operation and effect can be controlled without adding any new configuration.
It can be realized only by a simple change. Claim 2
1 and 22 prevent sudden increase in engine output torque
As a result, drivability can be maintained more favorably. Also
The swirl control valve is fully closed and the valve
You can wait for the overlap amount to decrease,
The combustion stability at the time of delivery can be more favorably maintained.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a schematic configuration of a gasoline engine system according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a variable valve timing mechanism system in the gasoline engine system.

FIG. 3 shows an EC in the gasoline engine system.
FIG. 3 is a block diagram showing a control system of U.

FIG. 4 is a flowchart showing a valve timing control process executed by the ECU.

FIG. 5 is a graph showing a control switching map in the air-fuel ratio control executed by the ECU.

FIG. 6 is a graph showing a map for setting a lean target valve timing tVTL in the valve timing control executed by the ECU.

FIG. 7 is a graph showing a map for setting a stoichiometric-rich target valve timing tVTR in the valve timing control executed by the ECU.

FIG. 8 is a flowchart of an air-fuel ratio control process performed in a second embodiment.

FIG. 9 is a condition graph illustrating opening / closing setting conditions of a swirl control valve SCV corresponding to air-fuel ratio control according to the second embodiment.

FIG. 10 is a graph showing an influence of opening and closing of a swirl control valve SCV on a valve overlap amount according to the second embodiment.

FIG. 11 is a flowchart of a combustion fluctuation feedback control process performed in the third embodiment.

FIG. 12 is a flowchart of a lean-burn feedback control process performed in the third embodiment.

FIG. 13 shows a stoichiometric operation performed in the third embodiment.
9 is a flowchart of a rich combustion feedback control process.

FIG. 14 is a graph showing a relationship between an air-fuel ratio and combustion fluctuation in the third embodiment.

FIG. 15 is a graph showing a relationship between a valve overlap amount and combustion fluctuation in the third embodiment.

FIG. 16 is a graph showing torque fluctuation and NOx generation compared between lean combustion based on the air-fuel ratio and combustion in the internal EGR of the valve overlap in the third embodiment.

FIG. 17 is a flowchart of a lean combustion feedback control process performed in the fourth embodiment.

FIG. 18 is a flowchart of a lean-burn feedback control process performed in the fourth embodiment.

FIG. 19 is a flowchart of a lean-burn feedback control process performed in the fifth embodiment.

FIG. 20 is a flowchart of a lean-burn feedback control process performed in the fifth embodiment.

FIG. 21 shows an engine speed NE in the fifth embodiment.
4 is a graph showing the relationship between the oil temperature and the response of the valve timing adjustment, and the relationship between the oil temperature and the response of the valve timing adjustment.

FIG. 22 is a flowchart of a valve timing control process performed in the sixth embodiment.

FIG. 23 is a timing chart showing effects in the sixth embodiment.

FIG. 24 is a timing chart showing a procedure for switching between a valve overlap amount and an air-fuel ratio in a conventional technique.

FIG. 25 is a graph illustrating two-stage setting of a valve overlap amount in a conventional technique.

FIG. 26 is a graph for explaining a problem of two-stage setting of a valve overlap amount in the related art.

FIG. 27 is a graph for explaining a problem of two-stage setting of a valve overlap amount in a conventional technique.

[Explanation of symbols]

10 ... V type 6 cylinder engine, 11 ... Cylinder block,
12L: left cylinder head, 12R: right cylinder head, 13: piston, 14: crankshaft, 1
5: combustion chamber, 16: spark plug, 17: injector,
18 ... Distributor, 19 ... Igniter, 20 ...
Intake passage, 21: intake valve, 22: intake port, 23
L: left intake side camshaft, 23R: right intake side camshaft, 24: air cleaner, 25: intake air amount sensor, 26: throttle valve, 27: intake side timing pulley, 27a: external teeth, 28: catalytic converter, 30 …
Exhaust passage, 31 ... Exhaust valve, 32 ... Exhaust port, 33
L: Left exhaust camshaft, 33R: Right exhaust camshaft, 34: Exhaust timing pulley, 35: Timing belt, 40: Crank angle sensor, 42: Cylinder discrimination sensor, 43: Water temperature sensor, 44L: Left cam angle Sensor, 44R right cam angle sensor, 45 throttle sensor, 46 air-fuel ratio sensor, 50, 50L, 50R variable valve timing mechanism, 51 bearing cap,
51a: first hydraulic pressure supply hole, 51b: second hydraulic pressure supply hole, 5
2: Inner cap, 52a: teeth, 53: hollow bolt,
54 pin, 55 cap, 56 housing, 5
6b: teeth, 57: bolt, 58: pin, 59: ring gear, 59a, 59b: teeth, 60: first hydraulic chamber, 61: second hydraulic chamber, 62: first hydraulic supply path, 63: second hydraulic supply Road, 64: oil pump, 64L, 64R: oil pump, 65: oil pan, 66L, 66R: oil filter, 70: electronic control unit (ECU), 71: ROM,
72: CPU, 73: RAM, 74: Backup RA
M, 75: bidirectional bus, 76: input interface,
77 ... Output interface, 80, 80L, 80R ...
Oil control valve (OCV), 81: electromagnetic actuator, 82: coil spring, 83: plunger, 84: spool, 84a: land, 84b:
Passage, 84c ... passage, 85 ... casing, 85
a ... A port, 85b ... B port, 85r ... reservoir port, 85t ... tank port, 90 ... BTDC, 91 ...
Bypass passage, 92 ... Idle speed control valve (ISCV).

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI F02D 43/00 301 F02D 43/00 301E 301Z 45/00 301 45/00 301G (58) Fields investigated (Int. Cl. ⁷ , (DB name) F02D 13/02 F02D 41/00-45/00 395

Claims (22)

(57) [Claims] 1. Lean combustion control for burning with an air-fuel mixture thinner than the stoichiometric air-fuel ratio, and stoichiometric combustion with an air-fuel mixture with a stoichiometric air-fuel ratio or an air-fuel mixture richer than the stoichiometric air-fuel ratio according to the operating state of the internal combustion engine. An internal combustion engine control device for performing rich combustion control, comprising: a variable valve timing mechanism capable of continuously adjusting a valve overlap amount between an intake valve and an exhaust valve of a combustion chamber of the internal combustion engine; A first pattern storing a set pattern of a valve overlap amount adjusted by the variable valve timing mechanism in accordance with an operation state of the engine;
Storage means; second storage means for storing a setting pattern of a valve overlap amount adjusted by the variable valve timing mechanism in accordance with an operation state of the internal combustion engine during the stoichiometric rich combustion control; Combustion control state determining means for determining whether the operating state of the engine is a lean combustion control state or a stoichiometric rich combustion control state; and determining that the operating state of the internal combustion engine is a lean combustion control state by the combustion control state determining means. In this case, the valve overlap is adjusted by the variable valve timing mechanism in accordance with the operation state of the internal combustion engine based on the set pattern of the valve overlap amount stored in the first storage means. If it is determined that the operating state of the internal combustion engine is in the stoichiometric rich combustion control state, On the basis of the setting pattern of the valve overlap amount stored in unit, a valve timing control means for setting the valve overlap amount is adjusted by an internal combustion engine wherein the variable valve timing mechanism corresponding to the operation state of, Whether the combustion fluctuation of the internal combustion engine is larger than the combustion fluctuation judgment value a
And a combustion control state determining means for determining whether a stoichiometric rich combustion control is performed.
Control is performed, and the combustion fluctuation determination
In stage a, the combustion fluctuation is larger than the combustion fluctuation judgment value a.
Is determined, the valve timing control means
The amount of valve overlap set by
Stoichiometric correcting the fence consisting direction - Rich time correction means
And an internal combustion engine control device comprising: 2. The stoichiometric rich correction means according to claim 1, wherein
So that the combustion fluctuation converges on the combustion fluctuation determination value a.
Feedback control of the lube overlap amount.
The internal combustion engine control device according to claim 1, wherein: 3. The stoichiometric air-fuel ratio according to the operating state of the internal combustion engine.
Lean combustion control to burn with a mixture that is thinner than
With a stoichiometric air-fuel mixture or a mixture that is richer than the stoichiometric air-fuel ratio
Internal combustion engine for stoichiometric rich combustion control
A control device, comprising a valve between an intake valve and an exhaust valve of a combustion chamber of an internal combustion engine.
Variable valve tie that can continuously adjust the amount of overlap
And the operating state of the internal combustion engine during the lean combustion control.
In response, it is adjusted by the variable valve timing mechanism.
First to store the setting pattern of the valve overlap amount
Storage means for operating the internal combustion engine during the stoichiometric rich combustion control;
In response to the rolling state, the variable valve timing mechanism
Describe the setting pattern of the valve overlap amount to be adjusted.
A second storage means for storing whether the operating state of the internal combustion engine is a lean combustion control state or a
Combustion control state to determine whether toy-rich combustion control state
The operating state of the internal combustion engine is determined by the determining means and the combustion control state determining means.
If it is determined that the vehicle is in the lean combustion control state,
The valve overlap stored in the first storage means;
The operation state of the internal combustion engine is
Correspondingly adjusted by the variable valve timing mechanism
Set the valve overlap amount to determine the operating state of the internal combustion engine.
Is determined to be in the stoichiometric rich combustion control state.
The valve stored in the second storage means.
Based on the overlap amount setting pattern, the internal combustion engine
To the variable valve timing mechanism corresponding to the operating state of
Valve to set the amount of valve overlap adjusted
The timing control means and whether the combustion fluctuation of the internal combustion engine is larger than the combustion fluctuation judgment value b
Lean combustion control is performed by the combustion fluctuation determination means b for determining whether or not the
And the combustion fluctuation determination means b
If it is determined that the burning fluctuation is greater than the combustion fluctuation determination value b,
If the air-fuel ratio of the air-fuel mixture is
An internal combustion engine control apparatus characterized by comprising: a lean time correction means for correcting the direction, the. 4. The control of an internal combustion engine according to claim 1 or 2.
Whether the combustion fluctuation of the internal combustion engine is larger than the combustion fluctuation judgment value b with respect to the configuration of the device
Lean combustion control is performed by the combustion fluctuation determination means b for determining whether or not the
And the combustion fluctuation determination means b
If it is determined that the burning fluctuation is greater than the combustion fluctuation determination value b,
If the air-fuel ratio of the air-fuel mixture is
An internal combustion engine control apparatus characterized by comprising: a lean time correction means for correcting the direction, the. 5. The lean-time correction means includes means for detecting a change in combustion before
The air-fuel ratio of the air-fuel mixture is converged to the combustion fluctuation determination value b.
4. The feedback control of the ratio.
Or the internal combustion engine control device according to 4. 6. An internal combustion engine according to claim 3,
The combustion variation set to a value smaller than the combustion variation determination value b with respect to the configuration of the related control device.
Whether the combustion fluctuation of the internal combustion engine is larger than the dynamic determination value c
And the valve timing set by the valve timing control means.
-Correct the burlap amount in a direction to reduce combustion fluctuation
A second lean time correction unit provided with a lean burn control is performed by the combustion control state judging means
And the combustion fluctuation determining means c determines
If it is determined that the burning fluctuation is greater than the combustion fluctuation determination value c,
In this case, the lean correction means is made to function, and the combustion control is performed.
It is determined that lean combustion control is being performed by the
And the combustion fluctuation is determined by the combustion fluctuation determining means c.
If it is determined that the value is smaller than the grilling fluctuation determination value c,
Characterized in that to function serial second rie on time correction means
Internal combustion engine control device. 7. The combustion control apparatus according to claim 2, wherein the second lean correction means is configured to control a combustion fluctuation.
Valve over so that convergence to the combustion fluctuation determination value d.
-Feedback control of lap amount
An internal combustion engine control device according to claim 6. 8. An internal combustion engine control according to claim 6 or 7.
Correction of the air-fuel ratio of the air-fuel mixture by the lean-time correction means with respect to the configuration of the device
Is adjusted to a mixture richer than the concentration determination reference value?
And a combustion control state determining means for performing lean combustion control.
And the combustion fluctuation determining means c determines
If it is determined that the combustion fluctuation is smaller than the combustion fluctuation determination value c,
In this case, the concentration adjustment determining means determines the air-fuel ratio of the air-fuel mixture.
The correction is adjusted to a mixture that is darker than the concentration determination reference value.
When it is determined that the second lean correction means is
Functioning the lean correction means without functioning.
An internal combustion engine control device characterized by the following. 9. An internal combustion engine according to claim 3,
The rotational speed of the internal combustion engine is detected for the configuration of the related control device , and the rotational speed is determined based on the determined rotational speed.
And a valve timing set by the valve timing control means.
-Correct the burlap amount in a direction to reduce combustion fluctuation
A third lean time correction means, provided with a lean burn control is performed by the combustion control state judging means
Has been determined, and the internal combustion engine speed determination means
If the rotation speed is determined to be smaller than the
Makes the lean correction means function, and sets the combustion control
The state determination means determines that lean combustion control is being performed.
And the rotation speed is determined by the internal combustion engine speed determination means.
If it is determined that the rotation speed is higher than the rotation speed,
Internal combustion engine characterized in that the start-up time correction means functions.
Control device. 10. The combustion control device according to claim 3, wherein the third lean correction means is configured to control a combustion variation.
So that the movement converges to the combustion fluctuation determination value e.
Feedback control of the burlap amount.
The internal combustion engine control device according to claim 9. 11. The method according to claim 3, wherein
With respect to the configuration of the fuel engine control device, the variable valve timing mechanism is operated by supplying hydraulic fluid.
As well as ability, the hydraulic fluid temperature detection means for detecting a temperature of the hydraulic fluid, the temperature of the hydraulic fluid detected by the hydraulic fluid temperature detection means
Fluid temperature to determine whether the temperature is within the allowable temperature range
A constant section, in the hydraulic fluid temperature determining means, the temperature of the hydraulic fluid is permitted temperature
If it is determined that it is not within the range, the second resource
The lean time correction means or the third lean time correction means functions
An internal combustion engine control device comprising: a correction prohibition unit that prohibits the operation from being performed . 12. The control means according to claim 12, wherein said correction prohibiting means is provided for detecting said operating fluid temperature.
The temperature of the hydraulic fluid is within the allowable temperature range
If it is determined that there is no second lean correction means,
Or, the third lean time correction means is prohibited from functioning.
And making the lean correction means function.
The internal combustion engine control device according to claim 11, wherein: 13. A stoichiometric engine according to an operating state of an internal combustion engine.
Lean combustion control to burn with a mixture that is thinner than the fuel ratio,
A stoichiometric air-fuel mixture or a mixture richer than the stoichiometric air-fuel ratio
Internal combustion engine that performs stoichiometric rich combustion control for combustion in a combustion chamber
A control device, comprising: an intake valve and an exhaust valve of a combustion chamber of an internal combustion engine.
Variable valve tie that can continuously adjust the amount of overlap
And the operating state of the internal combustion engine during the lean combustion control.
In response, it is adjusted by the variable valve timing mechanism.
First to store the setting pattern of the valve overlap amount
Storage means for operating the internal combustion engine during the stoichiometric rich combustion control;
In response to the rolling state, the variable valve timing mechanism
Describe the setting pattern of the valve overlap amount to be adjusted.
A second storage means for storing whether the operating state of the internal combustion engine is a lean combustion control state or a
Combustion control state to determine whether toy-rich combustion control state
The operating state of the internal combustion engine is determined by the determining means and the combustion control state determining means.
If it is determined that the vehicle is in the lean combustion control state,
The valve overlap stored in the first storage means;
The operation state of the internal combustion engine is
Correspondingly adjusted by the variable valve timing mechanism
Set the valve overlap amount to determine the operating state of the internal combustion engine.
Is determined to be in the stoichiometric rich combustion control state.
The valve stored in the second storage means.
Based on the overlap amount setting pattern, the internal combustion engine
To the variable valve timing mechanism corresponding to the operating state of
Valve to set the amount of valve overlap adjusted
The operation state of the internal combustion engine is determined by the timing control means and the combustion control state determination means.
From the determination that the engine is in the lean combustion control state,
Switch to the switch combustion control state,
The valve timing control means used in the
The setting pattern of the valve overlap amount is described in the first description.
From the setting pattern stored in the storage means.
Gradually switch to the setting pattern stored in the means
An internal combustion engine control device comprising gradual change means. 14. The method according to claim 1, wherein
With respect to the configuration of the fuel engine control device, the operating state of the internal combustion engine is
From the determination that the engine is in the lean combustion control state,
Switch to the switch combustion control state,
The valve timing control means used in the
The setting pattern of the valve overlap amount is described in the first description.
From the setting pattern stored in the storage means.
Gradually switch to the setting pattern stored in the means
An internal combustion engine control device comprising gradual change means. 15. An internal combustion engine according to claim 13 or 14.
Request for detecting the degree of acceleration request for the internal combustion engine for the configuration of the
Output means and an acceleration request detection means,
If there is a speed request, the gradual change means will not function
An internal combustion engine control device comprising: a gradual change inhibiting unit . 16. A stoichiometric engine according to an operation state of an internal combustion engine.
Lean combustion control to burn with a mixture that is thinner than the fuel ratio,
A stoichiometric air-fuel mixture or a mixture richer than the stoichiometric air-fuel ratio
Internal combustion engine that performs stoichiometric rich combustion control for combustion in a combustion chamber
A control device, comprising: an intake valve and an exhaust valve of a combustion chamber of an internal combustion engine.
Variable valve tie that can continuously adjust the amount of overlap
And the operating state of the internal combustion engine during the lean combustion control.
In response, it is adjusted by the variable valve timing mechanism.
First to store the setting pattern of the valve overlap amount
Storage means for operating the internal combustion engine during the stoichiometric rich combustion control;
In response to the rolling state, the variable valve timing mechanism
Describe the setting pattern of the valve overlap amount to be adjusted.
A second storage means for storing whether the operating state of the internal combustion engine is a lean combustion control state or a
Combustion control state to determine whether toy-rich combustion control state
The operating state of the internal combustion engine is determined by the determining means and the combustion control state determining means.
If it is determined that the vehicle is in the lean combustion control state,
The valve overlap stored in the first storage means;
The operation state of the internal combustion engine is
Correspondingly adjusted by the variable valve timing mechanism
Set the valve overlap amount to determine the operating state of the internal combustion engine.
Is determined to be in the stoichiometric rich combustion control state.
The valve stored in the second storage means.
Based on the overlap amount setting pattern, the internal combustion engine
To the variable valve timing mechanism corresponding to the operating state of
Valve to set the amount of valve overlap adjusted
Timing control means, the first storage means and the second storage means
The setting pattern of the valve overlap amount depends on the internal combustion engine
With parameter of load of engine and rotation speed of internal combustion engine
Internal combustion characterized by a map of the amount of overlap
Engine control device. 17. The first storage means and the second storage.
The setting pattern of the valve overlap amount stored in the means
The load parameter of the internal combustion engine and the rotational speed of the internal combustion engine are parameters.
Data must be a map of the valve overlap amount
Internal combustion engine according to any one of claims 1 to 15, wherein
Seki control device. 18. The method according to claim 1 , wherein
For the configuration of the fuel engine control device, a flow that can adjust the flow resistance of the gas passing through the combustion chamber
In the lean combustion control state by the resistance adjusting means and the combustion control state determining means,
If it is determined that
Increase resistance and control stoichiometric rich combustion
Is determined by the flow resistance adjusting means.
An internal combustion engine control device comprising: flow resistance control means for reducing drag . 19. The combustion resistance adjusting device according to claim 19 , wherein
The feature is to adjust the flow resistance on the intake side of
19. The internal combustion engine control device according to claim 18, wherein: 20. The swirl resistance adjusting means, comprising:
Claims characterized in that it also serves as a control valve
20. The internal combustion engine control device according to 18 or 19. 21. Internal combustion by said combustion control state determining means
When the operating state of the engine changes from the lean combustion control state to the stoichiometric
Switch to the combustion control state
Starts stoichiometric rich combustion control at the time of the determination,
After that, when the grace period Q elapses, the flow resistance adjustment is performed.
Means to reduce the flow resistance due to
The roll valve is opened, and the operating state of the internal combustion engine is determined by the combustion control state determining means.
From stoichiometric rich control to lean control
When it is determined that has been switched to
Before increasing the flow resistance by the flow resistance adjusting means,
Close the swirl control valve and allow time afterwards
Starting lean combustion control when the interval P has elapsed
21. The internal combustion engine control device according to claim 20, wherein: 22. The stoichiometric engine according to the operating state of the internal combustion engine.
Lean combustion control to burn with a mixture that is thinner than the fuel ratio,
A stoichiometric air-fuel mixture or a mixture richer than the stoichiometric air-fuel ratio
Internal combustion engine that performs stoichiometric rich combustion control for combustion in a combustion chamber
A control device, comprising: an intake valve and an exhaust valve of a combustion chamber of an internal combustion engine.
Variable valve tie that can continuously adjust the amount of overlap
And the operating state of the internal combustion engine during the lean combustion control.
In response, it is adjusted by the variable valve timing mechanism.
First to store the setting pattern of the valve overlap amount
Storage means for operating the internal combustion engine during the stoichiometric rich combustion control;
In response to the rolling state, the variable valve timing mechanism
Describe the setting pattern of the valve overlap amount to be adjusted.
A second storage means for storing whether the operating state of the internal combustion engine is a lean combustion control state or a
Combustion control state to determine whether toy-rich combustion control state
The operating state of the internal combustion engine is determined by the determining means and the combustion control state determining means.
If it is determined that the vehicle is in the lean combustion control state,
The valve overlap stored in the first storage means;
The operation state of the internal combustion engine is
Correspondingly adjusted by the variable valve timing mechanism
Set the valve overlap amount to determine the operating state of the internal combustion engine.
Is determined to be in the stoichiometric rich combustion control state.
The valve stored in the second storage means.
Based on the overlap amount setting pattern, the internal combustion engine
To the variable valve timing mechanism corresponding to the operating state of
Valve to set the amount of valve overlap adjusted
Adjusting the flow resistance on the intake side of the combustion chamber by adjusting timing control means;
A means that can adjust the flow resistance of gas passing through the firing chamber.
Flow resistance adjustment that also serves as a swirl control valve
Means in the lean combustion control state by the combustion control state determination means.
If it is determined that
Increase resistance and control stoichiometric rich combustion
Is determined by the flow resistance adjusting means.
Flow resistance control means for reducing drag, and the combustion control state determination means resets the operating state of the internal combustion engine.
From stoichiometric combustion control state to stoichiometric rich combustion control state
When it is determined that the
The toy-rich combustion control is started, and then the grace period Q
When the flow resistance is adjusted by the flow resistance adjusting means.
Open the swirl control valve to reduce
Come, scan the operating state of the internal combustion engine by the combustion control state judging means
From the toy-rich combustion control state to the lean combustion control state
When it is determined that the
In order to increase the flow resistance by the flow resistance adjusting means,
Close the swirl control valve, then grace time
Special feature is to start lean combustion control when P has elapsed.
Internal combustion engine control device.