JPH0734918A - Controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To increase reduction performance of toxic component in exhaust air by operating external load at the time of idle operation immediately after cold start and increasing load and intake air flow. CONSTITUTION:An auxiliary air control valve 5 provided in an auxiliary air passage 4 which is provided by bypassing a throttle valve 3 is controlled by an engine speed control means 9. However, when it is detected that external load is not operating at the time of cold idle operation, external load is put in the operating condition forcedly by an external load operating means. Even if idle engine speed is increased to correspond to external load, the operation of external load is stopped when it is judged that target engine speed cannot be maintained due to the operation of external load by an idle engine speed maintenance possible judging means because external load is put in the operating condition forcedly. As a consequence, it becomes possible to maintain rise of engine speed which corresponds to increase of external load, and rise of exhaust air temperature becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for promoting warm-up of a catalyst provided in an exhaust passage of the engine at the time of starting.

[0002]

2. Description of the Related Art In an internal combustion engine, feedback control is performed to converge the idle speed to a predetermined target speed according to the engine temperature in order to improve fuel economy performance and exhaust performance during idling. This control is carried out, for example, in JP-A-5
As disclosed in Japanese Patent Laid-Open No. 5-123336 and Japanese Patent Laid-Open No. 63-235642, the intake air amount supplied to the engine is adjusted according to the deviation between the actual idle speed and the target speed. However, in addition to this, immediately after the engine is started at the time of cold engine, the ignition timing is retarded in order to accelerate the warm-up of the catalyst device provided in the exhaust system, and the exhaust temperature is raised to improve the performance of the catalyst device. Has been done.

Further, as a control technique for enhancing the performance of the catalyst device, there is also a technique for retarding the ignition timing even during steady operation after warm-up, as disclosed in Japanese Patent Laid-Open No. 61-76741. . Further, as disclosed in JP-A-63-198747, at the end of the rapid warm-up control, the ignition timing retard correction is canceled, and at the same time, the intake air flow rate is quickly reduced, immediately after the low temperature start. There is also one that aims to prevent an increase in the number of revolutions when returning to the normal idle operation by correcting the ignition timing at the time of idling.

[0004]

However, in such a conventional control apparatus for an internal combustion engine, the ignition timing is retarded in order to promote warm-up of the catalyst device at the time of idling immediately after the start of the cold engine. There is a fear that the engine speed will decrease. In order to prevent this, control was performed to increase the intake air amount of the engine, but since it is ignition timing retard control during cold idling, which is an operating region near the stability limit, the ignition timing retard The deterioration of combustion due to the control became large, and there was a possibility that the stability could not be improved only by increasing the intake air amount to prevent the reduction of the rotation speed. That is, there is a problem that sufficient warm-up of the catalyst device while ensuring idle stability cannot be achieved by simply retarding the ignition timing.

In view of exhaust gas regulations, which are expected to become stricter in the future, it is indispensable to warm up the catalyst device as soon as possible immediately after the cold engine is started. It was impossible to deal with the above-mentioned conventional techniques. The present invention has been made in view of the above problems, and activates an external load such as an air conditioner or an alternator during idle operation immediately after the start of a cold machine to increase the engine speed and increase the load to increase the intake air flow rate. By increasing the amount, it is intended to improve the exhaust performance and significantly improve the performance of reducing harmful components in the exhaust while ensuring good idle stability.

[0006]

Therefore, the present invention is based on FIG.
As shown in, an auxiliary air control valve is provided in an auxiliary air passage provided by bypassing a throttle valve installed in the intake system of the engine, and a catalyst for purifying exhaust gas is installed in the exhaust system of the engine. In an internal combustion engine, an operating state detecting means for detecting an engine operating state including at least the engine temperature, an external load detecting means for detecting an operating state of an external load, and the operating state detecting means when the engine is in a cold idling state and When the external load detecting means detects that the external load is inactive, the external load operating means forcibly bringing the external load into the operating state and the idle by controlling the control amount to the auxiliary air control valve A rotation speed control means for controlling the rotation speed to a target rotation speed, and an idle rotation by the rotation speed control means when an external load is activated by the external load operation means. Is determined to be unable to maintain the target rotation speed due to the operation of the external load, and the idle rotation speed maintainability determination means for determining whether or not the target rotation speed can be maintained. And an external load operation stopping means for stopping the operation of the external load.

[0007]

According to the above construction, the auxiliary air control valve provided in the auxiliary air passage bypassing the throttle valve is controlled by the rotation speed control means, but the external load is not operated during the idling of the cooling machine. When it is detected that the external load is present, the external load actuating means forcibly activates the external load.

Further, the rotation speed control means controls the amount of control to the auxiliary air control valve in accordance with the external load to control the idle rotation speed, but the external load operating means activates the external load. At this time, the idle speed maintainability determination means determines whether the idle speed control means can maintain the idle speed at the target rotation speed.

When the external load is forcibly activated and the idle speed is increased to match the external load, the idle speed maintainability determining means operates the external load to achieve the target speed. When it is determined that the engine speed cannot be maintained, the operation of the external load is stopped, so that it is possible to maintain the increase of the engine speed corresponding to the increase of the external load, and it is possible to increase the exhaust temperature. Therefore, the catalyst can be activated more quickly.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2 showing the system configuration of the first embodiment according to the present invention, the air from the air cleaner 1 passes through an intake duct 2 and a throttle valve 3 that interlocks with an accelerator pedal (not shown) and an auxiliary device that bypasses the throttle valve 3. It is inhaled under the control of an electromagnetic auxiliary air control valve 5 installed in the air passage 4. Then, it is mixed with the fuel injected from the fuel injection valve 7 in the intake manifold 6 and is sucked into the engine 8.

The auxiliary air control valve 5 is designed to send a pulse signal to a valve opening coil and a valve closing coil (not shown) in a state in which the pulse signals are inverted from each other. In controlling the opening by controlling the pulse width of the pulse signal applied to the valve opening coil in the cycle, the opening is controlled according to the time ratio% of the pulse width to the cycle).

The duty of the pulse signal is controlled by the control unit 9, and for such control, signals from various sensors are input to the control unit 9. As the various sensors, a rotation speed sensor 10 is provided to detect the engine rotation speed Ne. Also, the throttle valve 3
Further, an idle switch 11 which is turned on in the fully closed position is attached to the. Further, a water temperature sensor 12 is provided to detect the engine cooling water temperature Tw. In addition, a signal from an air conditioner switch 22 for determining whether the air conditioner 14 is operating or not, which will be described later, is input.

The control unit 9 also receives a neutral signal from a neutral switch 30 of the transmission (not shown). Explaining the air conditioner 14, the air conditioner 14 includes at least a compressor 15 arranged in an engine room (not shown) and an air conditioner fan 16 for blowing cool air or the like into the passenger compartment.
Is driven by a crank pulley through a belt or the like.

Here, the microcomputer in the control unit 9 calculates the duty to the auxiliary air control valve 5 based on the signals from the various sensors according to the idle speed control routine shown in the flowchart of FIG. The opening is controlled. Here, the control of the internal combustion engine performed by the control unit 9 according to the program shown in the flowchart of FIG. 3 will be described.

The routine shown in the flow chart of FIG. 3 is a control program for the internal combustion engine according to the first embodiment of the present invention, and is executed every 10 msec. Further, the function of the rotation speed control means is performed by the routine. In step 1 (denoted as S1 in the figure, the same applies hereinafter), the air conditioner switch 22 is turned off.
N / OFF determination is performed, and when it is ON, the load of the air conditioner as an external load is already acting on the engine 8, and the process directly returns.

If it is judged to be OFF in step 1, the process proceeds to step 2 and the subsequent steps to carry out this control. That is, step 1 has the function of the external load detection means. In step 2, the fully closed position signal of the throttle valve 3 is read from the idle switch 11.

In step 3, the engine speed Ne is detected based on the signal from the speed sensor 10, and the cooling water temperature Tw as the engine temperature is detected by the water temperature sensor 12. That is, the rotation speed sensor 10, the water temperature sensor 12 and the like constitute an operating state detecting means. In step 4, the cooling water temperature T
Based on w, it is determined whether or not it is in an operating region (hereinafter referred to as a cold idle region) in which various controls to be described later need to be performed in order to promote warm-up. Here, for example, as shown in FIG. 4, when the cooling water temperature Tw is equal to or lower than the reference cooling water temperature Tw ₀ (Tw ≦ Tw ₀ ), it is determined to be in the cooling idle region, the process proceeds to step 5 and lower, and Tw> If Tw ₀ , proceed to step 9.

In step 5, by reading the fully closed position signal of the throttle valve 3 from the idle switch 11, it is determined whether or not the throttle valve 3 is in the idle position, and it is determined that the throttle valve 3 is in the idle state. Only if so, go to step 6. In step 6, the neutral signal from the neutral switch 30 of the transmission or the parking signal from the parking switch is read to determine whether or not the transmission is in the neutral state. Only in the neutral state, the step 7 Continue below.

If it is determined in step 5 and step 6 that the transmission is no longer in the idle state, or if it is determined that the transmission is not in the neutral state, the process proceeds to step 9. That is, the control according to the present invention described below is performed only when the engine 1 is in a cold state and the vehicle equipped with the engine 1 is stopped and the engine 1 is warmed up.

At step 7, the air conditioner fan 16 is turned on.
Instead, only the compressor 15 of the air conditioner 14 is forcibly turned on to load the engine 8. That is, step 7 performs the function of the external load operating means. In step 8, it is impossible to perform the cold idling control in the cold idling region because the opening duty of the auxiliary air control valve 5 exceeds the limit value or the like while the engine is forcibly loaded with the external load. If it is determined that the cold machine idle control can be performed, the process proceeds to step 9.

In step 9, the idle speed control such as increasing the engine speed Ne to the target engine speed is performed, and the cooling idle control is continued. On the other hand, if it is determined in step 8 that the cold idle control cannot be performed, the process proceeds to step 10. In step 10, the compressor 15 forcedly turned on in step 7 is turned off, the engine 8 is returned to the unloaded state, and then the process returns.

That is, in steps 7 to 9, the engine 8
Is forcibly loaded to determine whether it is possible to perform cold idle control in this state. If it is determined that it is possible, cold idle control is performed with the load forced. Will be done. Therefore, in steps 7 to 9, it is determined whether or not the idle speed can be maintained at the target speed by the speed control means when the external load is activated by the external load actuation means. Therefore, the functions of the idle speed maintainability determination means are performed by steps 7 to 9.

In steps 8 and 10, the compressor 15 is stopped when it is determined that the idle speed cannot be maintained at the target speed when the compressor 15 as the external load is operated. The functions of the external load operation stopping means are performed by the steps 8 and 10. Therefore, as described above, according to the first embodiment, as shown by the solid line in FIG. 5, the cold idling control is performed in a state where the load is forcibly applied at the time of idling immediately after the low temperature start. It is possible to raise the exhaust gas temperature while appropriately increasing the engine speed Ne, and it is possible to activate the three-way catalyst earlier.

Therefore, the catalyst activation immediately after the low temperature start can be promoted, and the effect of improving the exhaust gas purification performance can be obtained. Next, the control according to the second embodiment of the present invention will be described with reference to the flowcharts of FIGS. 6 and 7. still,
Steps having the same operations as those in the flowchart shown in FIG. 3 are designated by the same step numbers and description thereof will be omitted.
The routine is also executed every 10 msec, and the function of the rotation speed control means is performed by the routine.

As a system configuration according to the second embodiment, the engine 8 is provided with an alternator and a power steering pump (not shown), and like the compressor 15 and the air conditioner fan 16, the engine 8 is operated by the engine 8. It is driven via a belt or the like. In step 21, based on the cooling water temperature Tw, it is determined whether or not it is an operating region (hereinafter referred to as a cooling idle period) in which various controls to be described later need to be performed in order to promote warming up. Here, for example, as shown in FIG. 4, the cooling water temperature Tw is equal to or lower than the reference cooling water temperature Tw ₀ (Tw
≦ Tw ₀ ), it is determined to be in the cold idle region,
The process proceeds to step 22 and onward, and returns if Tw> Tw ₀ .

In step 22, it is judged by reading the fully closed position signal of the throttle valve 3 from the idle switch 11 whether or not the throttle valve 3 is in the idle position, and it is judged that the throttle valve 3 is in the idle state. Only if so, go to step 23. Further, in step 23, it is determined whether or not the transmission is in the neutral state by reading the neutral signal from the neutral switch 30 of the transmission or the parking signal from the parking switch. Only in the neutral state, the step 24 is performed. Continue below.

If it is determined in steps 22 and 23 that the transmission is no longer in the idle state, or if it is determined that the transmission is not in the neutral state, the process returns. That is, the control according to the present invention described below is performed only when the engine 1 is in a cold state and the vehicle equipped with the engine 1 is stopped and the engine 1 is warmed up.

At step 24, the air conditioner switch 22 is turned off.
N / OFF determination is performed, and when ON, it is determined that the load of the air conditioner as an external load is already acting on the engine 8, and the routine jumps to step 31. OFF in step 24
If it is determined that,
An air conditioner as an external load is forcibly applied to the engine 8 as a load to perform cold idle control.

That is, the step 24 has the function of the external load detecting means. In step 8, while the external load is forcibly applied to the engine, for example, when the opening duty of the auxiliary air control valve 5 exceeds the limit value,
When it is determined whether it is possible to perform the cold idle control in the cold idle region, and when it is determined that the cold idle control can be performed,
Go to step 25.

In step 25, for example, idle speed control such as increasing the engine speed Ne to the target engine speed is carried out, and then cold engine idle control is carried out. On the other hand, if it is determined in step 8 that it is impossible to perform the cooling idle control, the process proceeds to step 26, and the compressor 15 forcibly turned on in step 7 is used.
Is turned off to return the engine 8 to the no-load state, and the process proceeds to step 31.

In step 31, it is judged whether or not the alternator is operating. When the alternator is operating, it is determined that the load of the alternator as an external load is already acting on the engine 8, and the process jumps to step 41. If it is determined to be OFF in step 31, the process proceeds to step 32 and thereafter, and an alternator as an external load is forcibly applied to the engine 8 as a load to perform cold idle control.

That is, the step 31 performs the function of the external load detecting means. In step 32, the alternator is forcibly turned on, and the engine 8 is under load. That is, step 32 performs the function of the external load operating means. In step 33, it is impossible to perform the cold idling control in the cold idling region, for example, because the opening duty of the auxiliary air control valve 5 exceeds the limit value while the external load is forcibly applied to the engine. If it is determined that the cooler idle control can be performed, the process proceeds to step 34.

In step 34, idle speed control such as increasing the engine speed Ne to the target engine speed is performed, and the cold engine idle control is continued. On the other hand, if it is determined in step 33 that the cold idle control cannot be performed, the process proceeds to step 35, the alternator forcibly turned on in step 32 is turned off, and the engine 8 is unloaded. After returning to the state, proceed to step 41.

In step 41, the operation of the power steering pump is determined, and when the power steering pump is operating, the engine 8 is already subjected to the load of the power steering pump as an external load, and the routine returns. Step
When it is judged to be OFF in 41, the routine proceeds to step 42 and thereafter, and the power steering pump as an external load is forcibly applied to the engine 8 as a load to perform the cold idle control.

That is, the step 41 performs the function of the external load detecting means. In step 42, the power steering pump is forcibly turned on, and the engine 8 is under load. That is, step 42 performs the function of the external load operating means. In step 43, it is impossible to perform the cold idling control in the cold idling region, for example, because the opening duty of the auxiliary air control valve 5 exceeds the limit value while the engine is externally forcibly loaded. If it is determined that the cold machine idle control can be performed, the routine proceeds to step 44.

In step 44, the idle speed control such as increasing the engine speed Ne to the target engine speed is performed, and the cooling idle control is continued. On the other hand, if it is determined in step 43 that it is impossible to perform the cooling idle control, the process proceeds to step 45, in which the power steering pump forcedly turned on in step 42 is turned off and the engine 8 is turned off. After returning to the unloaded state, the process returns.

That is, in the second embodiment, first, in steps 7, 8 and 25, the engine 8 is forcibly loaded by the compressor 15 of the air conditioner 14, and the cooler idle control can be performed in this state. If it is determined that it is possible, the cooling machine idle control is performed with the load being forcibly applied. Then, in steps 32-34, the engine 8 is forcibly loaded by the alternator, and it is determined whether or not the cold idle control can be performed in this state, and it is determined that it is possible. In this case, the cold machine idle control is performed with the load being forcibly applied. Further, in steps 42 to 44, next, the engine 8 is forcibly loaded with a power steering pump, and it is determined whether or not it is possible to perform the cooling idle control in this state. If so, the cold machine idle control is performed under the condition that the load is forcibly applied.

Therefore, steps 7, 8 and 25, step
The functions of the idle speed maintainability determination means are performed by 32-34 and steps 42-44. In steps 8 and 26, the compressor 15 as the external load is used.
When it is determined that the idle rotation speed cannot be maintained at the target rotation speed when the engine is operated, the compressor 15 is stopped, and accordingly, the functions of the external load operation stopping means are performed by the steps 8 and 10. .

Similarly, in steps 33 and 35, it is judged whether or not the idle speed can be maintained when the alternator as an external load is forcibly operated. Playing the function of. Further, in steps 43 and 45, since it is determined whether or not the idle speed can be maintained when the power steering pump as the external load is forcibly operated, the steps 43 and 45 are the functions of the external load operation stopping means. Is playing.

Therefore, as described above, according to the second embodiment as well, at the time of idling immediately after the low temperature start, the cold idling control is performed under the condition that the load is forcibly applied in stages, so the engine speed Ne It is possible to raise the exhaust gas temperature while gradually increasing the engine speed to the target rotational speed, and it is possible to activate the three-way catalyst even earlier. Therefore, the catalyst activation immediately after the low temperature start can be promoted, and the effect of improving the exhaust gas purification performance can be obtained.

Further, in the second embodiment, since it is possible to increase the load stepwise, it is possible to minimize the rotational fluctuation of the idle speed in the cold idle control. Becomes Also, while detecting the operating state of the auxiliary machine, the auxiliary machine that can perform the cooler idle control is selected and forcibly operated, so the engine will operate the auxiliary machine as much as possible, which is possible for the engine. There is also an effect that the exhaust gas temperature can be increased as much as possible.

[0042]

As described above, according to the present invention, when it is detected that the engine is in a cold idling state and the external load is inactive, the external load is forcibly activated and the auxiliary A rotation speed control means for controlling the idle rotation speed to a target rotation speed by controlling a control amount to the air control valve, and an idle speed control means for controlling the idle speed when the external load is activated by the external load operation means. The idle speed maintainability determination means for determining whether or not the rotation speed can be maintained at the target speed, and the idle speed maintainability determination means determines that the target speed cannot be maintained due to the operation of the external load. Since the external load operation stopping means for stopping the operation of the external load is included, it is possible to increase the engine speed as much as possible with an increase in the external load. , To allow an effective increase in the exhaust temperature, it is possible to more quickly activate the catalyst with.

Therefore, there is an effect that the exhaust performance can be improved and the reduction performance of harmful components in the exhaust gas can be greatly improved while ensuring good idle stability.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of the present invention.

FIG. 2 is a schematic diagram showing a system configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing the control operation of the first embodiment of the present invention.

FIG. 4 is a characteristic diagram for determining whether to perform the control of the present invention.

FIG. 5 is a characteristic diagram illustrating actions and effects of this embodiment.

FIG. 6 is a flowchart showing the control operation of the second embodiment of the present invention.

FIG. 7 is a flowchart showing the control operation of the second embodiment of the present invention.

[Explanation of symbols]

 3 Throttle valve 5 Auxiliary air control valve 8 Engine 9 Control unit 12 Water temperature sensor 14 Air conditioner 15 Compressor 22 Air conditioner switch

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02D 45/00 310 BL

Claims (1)

[Claims] 1. An auxiliary air control valve is provided in an auxiliary air passage provided bypassing a throttle valve provided in an intake system of an engine, and a catalyst for purifying exhaust gas is provided in an exhaust system of the engine. In an internal combustion engine, an operating state detecting means for detecting an engine operating state including at least the engine temperature, an external load detecting means for detecting an operating state of an external load, and the operating state detecting means when the engine is in a cold idle state and When the external load detecting means detects that the external load is inactive, the external load operating means forcibly bringing the external load into the operating state and the idle by controlling the control amount to the auxiliary air control valve A rotation speed control means for controlling the rotation speed to a target rotation speed, and an idle speed control means for controlling the rotation speed when the external load is activated by the external load operation means. The idling speed maintainability judging means for judging whether or not the speed can be maintained at the target speed, and the idling speed maintainability judging means judges that the target speed cannot be maintained due to the operation of the external load. An external load operation stopping means for stopping the operation of the external load at times, and a control device for an internal combustion engine.