JPH0626432A - Ignition timing control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To activate a catalyzer at an early stage without damaging idle drive performance and fuel consumption by enumerating basic delay angle amount of ignition timing and correcting it in correspondence with opening of an idle control valve and elapsed time after starting at the time of idle drive after an engine starts. CONSTITUTION:When a drive condition detection means 1 detects a drive condition, a basic ignition timing enumeration means 2 enumerates basic ignition timing in accordance with it. In the meantime, a basic delay angle amount computing means 3 enumerates basic delay angle amount of the ignition timing required for activation of a catalyzer from cooling water temperature at the time of starting. Thereafter, a correction value computing means 4 computes correction value of the basic delay angle amount from opening of an idle control valve to increase air by way of by-passing an air suction throttle valve. Additionally, in parallel with it, a correction value computing means 5 computes the correction value of the basic delay angle amount in accordance with elapsed time after starting. Thereby, an idle delay angle amount enumeration means 6 enumerates idle delay angle amount by way of correcting the basic delay angle amount in accordance with both of the correction values, and the basic ignition timing is adjusted by basic ignition timing adjustment means 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling ignition timing of an internal combustion engine.

[0002]

2. Description of the Related Art Generally, the required ignition timing of an internal combustion engine differs depending on the operating conditions, and therefore, the basic ignition timing (MBT) is set so as to change depending on the engine load and engine speed. The basic ignition timing is further corrected on the condition of the engine cooling water temperature or the like in order to improve the warm-up performance immediately after the engine is started or to suppress knocking under a high load.

In order to improve the exhaust emission of the internal combustion engine, a three-way catalyst is installed in the exhaust system so that HC and CO
It is known that the oxidation of NOx and the reduction of NO are performed at the same time, but such a catalyst can maintain the desired exhaust gas purification efficiency only in an active state at a predetermined temperature or higher. Therefore, the exhaust emission increases until the catalyst temperature rises, such as during a cold start of the engine.Therefore, when the engine cooling water temperature is low, the ignition timing is retarded to raise the exhaust temperature and start as soon as possible after starting. It tries to restore the function of the catalyst. Note that this will also help to warm up the engine.

In Japanese Utility Model Laid-Open No. 57-75173, in order to realize early warm-up of the catalyst when the engine is cold without impairing operability, the distributor valve is operated via a switching valve that operates according to the engine cooling water temperature. Negative pressure generated in the vicinity of the intake throttle valve is selectively introduced into the negative pressure advance chamber to retard the ignition timing from the normal state when cold.

[0005]

However, when the ignition timing is retarded in this way, the output torque decreases, and the idle speed tends to become unstable, especially in the idle operation state. To reduce the idle speed, the engine speed can be restored by increasing the opening of the idle control valve that bypasses the intake throttle valve, but the ignition timing is extremely increased because the catalyst warms up. Even if the idle control valve is retarded, even if the idle control valve is set to the maximum opening, the rotation speed may not increase. In this case, the idle operation performance becomes extremely unstable.

When the catalyst is warmed up by retarding the ignition timing, if the ignition timing is returned to the normal ignition timing, a large torque shock is generated at the moment of return, and the driving performance is deteriorated. Is damaged. Further, the retard amount required for catalyst warm-up becomes smaller with the lapse of the retard control time after the start, but if the ignition timing is retarded more than necessary, the fuel consumption is deteriorated accordingly.

An object of the present invention is to control the ignition timing so as to activate the catalyst early without deteriorating the idle operation performance and fuel consumption.

[0008]

The present invention, as shown in FIG. 1, includes means 1 for detecting an operating condition, means 2 for calculating a basic ignition timing from the operating condition, and a catalyst based on a cooling water temperature at the time of starting. Means 3 for calculating the basic retardation amount of the ignition timing required for activation, and means 4 for calculating the correction value of the retardation amount from the opening of the idle control valve that bypasses the intake throttle valve and increases the air amount.
A means 5 for calculating a correction value of the retard angle amount according to the elapsed time after the start, and a means 6 for correcting the basic retard angle amount based on these correction values to calculate an idle retard amount. And means 7 for correcting the basic ignition timing based on the idle retard amount.

Further, the correction value calculation means 4 based on the opening of the idle control valve outputs a correction value such that the retard amount becomes zero when the opening of the idle control valve is near the maximum value.

[0010]

In order to raise the temperature of the catalyst during idle operation after the engine is started, when the basic retardation amount of the ignition timing is calculated, a correction corresponding to the opening of the idle control valve and the elapsed time after starting is calculated. The basic ignition timing is corrected based on this corrected retard amount.

Therefore, the idling speed does not become unstable due to the retardation for activating the catalyst, and the retardation amount becomes smaller as the retardation control time elapses. The occurrence of a torque step is also prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, 11 is an engine body, 12 is an intake passage, 13 is an exhaust passage, 14 is an intake valve, and 15 is an exhaust valve. A three-way catalyst 16 is installed in the exhaust passage 13 to oxidize HC and CO in the exhaust and reduce NO.

Reference numeral 17 is a fuel injection valve for injecting fuel into the intake passage 12, and reference numeral 18 is an ignition plug for igniting the air-fuel mixture in the combustion chamber 19.

A control device 21 is provided to control the injection amount from the fuel injection valve 17 and to control the ignition timing of the ignition device 20 that ignites the spark plug 18.

In order to maintain the conversion efficiency of the three-way catalyst 16 to the maximum, the control device 21 controls the intake air amount detected by the air flow sensor 22 so that the fuel injected from the fuel injection valve 17 has the stoichiometric air-fuel ratio. , The fuel injection amount is calculated according to the engine speed detected by the speed sensor 23.

Further, the control device 21 calculates the ignition timing of the spark plug 18 in accordance with the fuel injection pulse width corresponding to the engine load and the engine speed so that the ignition timing becomes the optimum ignition timing according to the operating condition. The engine cooling water temperature sensor 24 and the accelerator opening sensor 26 are arranged so that the basic ignition timing is retarded according to the activation state of the three-way catalyst 16 when the engine is warmed up.
Alternatively, control is performed according to detection signals from the throttle valve opening sensor 27, the rotation speed sensor 23, the air flow sensor 22, and the like.

Until the warm-up of the engine, such as when the engine is cold started, the temperature of the three-way catalyst 16 is low and is not activated, so that the three-way catalyst 16 cannot fully function and the ignition timing is delayed from the basic ignition timing. Thus, the exhaust gas temperature is raised, the three-way catalyst 16 is activated early, and the ignition timing retard amount is set based on the accelerator opening degree or the like so as not to deteriorate the engine operating performance during the warm-up. Correction control is performed as described later.

Further, the control device 21 controls the opening degree of the idle control valve 29 provided in the passage 28 bypassing the throttle valve 30 of the intake passage 12 so as to prevent the reduction of the idle rotation at the time of the retard correction as described later. Control to. Reference numeral 31 is an idle switch for detecting an idle state.

The retard correction of the ignition timing for the early activation of the three-way catalyst 16 at the time of warming up after the engine is started will be described with reference to the flowchart of FIG.

First, the starting condition of the engine is judged, and when starting the starter motor, the normal ignition timing control is performed to stabilize the starting, and then, after the complete explosion, the ignition timing is controlled according to the cooling water temperature to accelerate warming up. Shifts to retard correction control.

In step 1, it is judged whether or not the starter switch is on. If the start-up is on, the routine proceeds to steps 2-6.

The basic retard angle amount ADVTID of the ignition timing at the time of idling, which is necessary for promoting the warming up of the catalyst, is calculated by the table lookup from FIG. 4 based on the cooling water temperature TW at the time of starting. Basic delay amount A when not idle
DVTO is determined from FIG. 5 by table lookup.

The characteristics of these basic retardation amounts are:
In order to accelerate the catalyst warm-up, the retard amount is set to a relatively large value during idling, which has less influence on drivability, compared to during non-idling.

Further, in order to set the time for continuing the retard correction control and to obtain the reduction coefficient TIME for decreasing the correction value with the passage of time, the table look up is also made from FIG. 6 based on the cooling water temperature in the same manner. The set value TTMMP of the delay timer (delay time) is calculated in advance.

Next, in order to ensure a smooth start, the map for setting the ignition timing data for normal starting is set to ADVTMP = 0 as the retarding amount ADVTMP at the time of starting, that is, the retarding amount is set to zero. The ignition timing ADV is calculated by a table lookup according to (not shown), and the routine proceeds to step 24, where ignition timing ADV = ADV-ADVT
MP.

Therefore, at the time of this starting, there is no ignition timing retard correction, and a smooth starting of the engine is guaranteed.

When the starting operation is completed, steps 10 to 2
3, the ignition timing retard amount is calculated based on the retard angle data read at the time of starting.

When it is detected that the starter switch is off, the routine proceeds to step 10, where it is judged whether the TTMMP time set based on the cooling water temperature after the switch is off. This TTMMP has a larger value as the cooling water temperature at the start is lower, which means that the ignition timing retard correction is performed for a longer period after the start.

If the set time has not elapsed, the reduction coefficient RTIME = 1.0 is set in step 11. As will be described later, the reduction coefficient RTIME of 1.0 means that
It means that the calculated correction amount of the retard amount is 1.0, that is, the retard amount is retarded as it is according to the basic retard amount.

On the other hand, when the set time TMTMP has passed, in step 12, a predetermined TMT is further added.
MPG # Determine if time has elapsed. As shown in FIG. 7, until the TMTMPG # time elapses, the reduction coefficient TIME is a region in which it gradually becomes smaller than 1.0.
Is calculated.

TIME = │ (TMKAI-TMTM
P) -TMTMPG # | / TMTMPG # ... (1) However, TMKAI: elapsed time counter value after starter switch off It is calculated after the elapse of time TTMMP that the reduction coefficient RTIME is gradually decreased from 1.0. This is to reduce the retard correction amount and prevent the ignition timing from changing stepwise at the end of the retard correction.

The set time (TMTMP + TMTMP
When G #) has elapsed, the reduction coefficient RT is determined in step 14.
IME = 0 is set and the ignition timing retard correction is terminated.

As a result, the reduction coefficient TIME
After calculating, the process proceeds to step 15.

In step 15, whether the idling operation is performed or not is determined by turning on / off the idle switch 31, and different retardation correction characteristics of the ignition timing are taken accordingly. In other words, Steps 16-18 are for idle
Further, in steps 20 to 23, the retard amount during non-idle is calculated.

First, at the time of idling, a basic ignition timing ADV required for idling operation is obtained from a map (not shown),
Next, a correction factor GISMX (a value of 1.0 or less) for preventing the reduction of the idle speed due to the retard of the ignition timing is calculated by the following formula.

GISCMX = (ISCMAX-NRDT
Y # -RISCON) * GRETD # ... (2) where NRDTY #: a predetermined constant, GRET
D #: Predetermined coefficient Here, ISCMAX is a control value at which the idle control valve 29 becomes the maximum opening degree, and RISCON is the idle control valve 29.
Therefore, when the control duty approaches the maximum value ISCMAX, that is, when the idle control valve 29 is extremely wide open to prevent the idle rotation speed from decreasing, the retard angle amount is reduced. The correction factor GISCMX approaches zero as described above.

In step 18, the retard amount ADVTMP is calculated from the above-described correction coefficients GISMX and TIME based on the basic retard amount ADVTID read at the time of starting.
Is calculated by the following equation.

ADVTMP = ADVTID * GISCM
X * TIME ... (3) After calculating the retard amount, the routine proceeds to step 24, where the basic ignition timing ADV is corrected based on the retard amount ADVTMP.

The basic retard amount ADVTID becomes larger as the cooling water temperature becomes lower. Therefore, the retard amount from the optimum ignition timing becomes larger accordingly. By thus retarding, the exhaust temperature rises and the three-way catalyst 16 The rise in temperature is also accelerated.

Further, the correction coefficient GISCMX indicates the ignition timing when the opening degree of the idle control valve 29 for maintaining the idle speed at a predetermined value is large, that is, when the control for maintaining the idle speed has a small margin. The retard correction amount is reduced (limited), and the idle rotation is stabilized rather than the exhaust temperature is raised.

Further, as described above, the reduction coefficient RTIM
E becomes closer to zero as the elapsed time after starting becomes longer, the retard amount is gradually reduced, and when the retard correction is completed and the normal ignition timing is restored, before and after the completion. Eliminate the difference in ignition timing. This prevents unnecessary retardation to improve fuel efficiency and smooth drivability at the end of retardation control.

Next, at non-idle time, that is, when the accelerator pedal is depressed, the routine proceeds to step 20, where the ignition timing ADV at non-idle time is read from a map not shown, and then the correction term for the basic retardation amount is calculated. To do.

The correction terms ADVTN for engine speed shown in the map of FIG. 8 and ADVTTP for engine load shown in the map of FIG.
And the retard correction rate ADVTTV for the throttle opening (or accelerator opening) in FIG. 10, which are calculated by table lookup.

The correction factor ADVTN based on the rotation speed takes the maximum value (1.0) in the middle rotation speed range, and gradually decreases in the low rotation speed range where the retard cannot be greatly retarded from the point of surge and the high rotation range where the output cannot be retarded. Also, the correction factor ADVTTP depending on the load
The correction rate ADVTTV based on the throttle opening maintains a maximum value (1.0) up to a predetermined value, but above that, it gradually decreases from the output demand.

In step 22, the minimum value of these correction terms is set to the correction value GJYKEN = ADVTN, ADVTTP.
Or elected as ADVTTV.

Then, based on the basic delay amount ADVTO at the time of non-idle read at the time of starting at step 23,
The retard amount ADVTMP including this correction coefficient is calculated by the following equation, and in step 25, the basic ignition timing is corrected.

ADVTMP = ADVTO * GJYKEN
* TIME (4) Therefore, this retard correction amount changes according to the engine speed, the load, and the throttle opening, and is selected so that the retard amount is minimized. The operating performance of the engine, including acceleration and high-load operation, is maintained well.

It should be noted that, as with the control at the time of idling, the retard amount decreases with the lapse of time after the start, and the torque step can be prevented from occurring at the end of the retard correction.

Next, the control of increasing or decreasing the opening degree of the idle control valve 30 which bypasses the intake throttle valve 30 to allow the intake air to flow in order to compensate for the decrease in the torque due to the ignition timing retard control is shown in the flowchart of FIG. Therefore, it will be explained.

When the ignition timing is delayed, the torque generated is relatively reduced. Therefore, the intake throttle valve 30 is bypassed to increase intake air to compensate for the decrease in torque,
Especially, it prevents the idle speed from becoming unstable.

First, in steps 30 to 31, various sensors are checked and idle conditions are checked, an idle rotation basic duty (DUTY) is calculated, and various idle rotation basic duties are calculated.

When the idle switch 31 is turned on, when it is turned on, the air amount ISCRTD for retarding the ignition timing is calculated at step 34.

ISCRTD = Qshw * ADVTMP *
ISRTID # ... (5) where Qshw: basic air amount, ISCRTID #: coefficient corresponding to the amount of torque decrease due to retard. On the other hand, when the idle switch 31 is off, the air amount is increased in the non-idle state in step 35. ISCRTD is calculated by the following equation.

ISCRTD = Qshw * ADVTMP *
ISRTNI # ... (6) In this case, ISCRTNI # becomes a coefficient for compensating for the decrease in torque, and in step 36, the control output duty ISC of the idle control valve 29 is calculated as follows.

ISC = basic duty + various correction amounts + IS
CRTD (7) The opening of the idle control valve 29 is controlled by this ISC, and the opening increases as the ISC increases.
The amount of air introduced by bypassing the throttle valve 30 increases, and the engine speed, which is reduced by the ignition timing retard control, is returned to the target value.

In step 37, the maximum ISC value I
Due to the relationship between SCMAX and the minimum value ISCMIN, the limit is set so that neither is exceeded.

Therefore, even when the ignition timing is retarded for activation of the three-way catalyst 16, fluctuations (decrease) in the engine speed caused by a decrease in the output torque of the engine are controlled by the opening degree of the idle control valve 29. It can be compensated by increasing the number, which makes it possible to maintain stable driving characteristics.

[0059]

As described above, according to the present invention, when the basic retardation amount of the ignition timing required to raise the temperature of the catalyst during the idle operation after the engine is started is calculated, the basic retardation amount of the idle control valve is calculated. Correction is made according to the opening degree and the elapsed time after starting, and the basic ignition timing is corrected based on this corrected retard amount, so the idle speed becomes unstable due to the retard angle for catalyst activation. In addition, the amount of retard angle becomes smaller with the lapse of the retard control time, deterioration of fuel efficiency due to excessive retard and the occurrence of torque step at the end of retard control are prevented, and the catalyst is warmed up early. It is possible to maintain good idle drivability.

Further, since the retarding angle is stopped near the maximum opening of the idle control valve, the idle speed does not become uncontrollable even when starting at an extremely low temperature.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a basic configuration of the present invention.

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

FIG. 3 is a flowchart showing an ignition timing retard control operation.

FIG. 4 is a characteristic diagram showing a basic retard angle amount during idling based on a relationship with a cooling water temperature.

FIG. 5 is a characteristic diagram showing a basic retard angle amount during non-idle based on a relationship with a cooling water temperature.

FIG. 6 is a characteristic diagram showing the delay time of the reduction coefficient based on the relationship with the cooling water temperature.

FIG. 7 is a characteristic diagram showing a characteristic of a reduction coefficient based on a relationship with time.

FIG. 8 is a characteristic diagram showing the relationship between the engine speed and the retardation amount correction rate.

FIG. 9 is a characteristic diagram showing a relationship between an engine load and a retardation amount correction rate.

FIG. 10 is a characteristic diagram showing the relationship between the throttle opening and the retardation amount correction rate.

FIG. 11 is a flowchart showing the control operation of the idle control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operating condition detection means 2 Basic ignition timing calculation means 3 Basic retardation amount calculation means 4 Correction value calculation means by idle control valve opening degree 5 Correction value calculation means by elapsed time after start 6 Idle retardation amount calculation means 7 Ignition timing Corrector 11 Engine body 12 Intake passage 13 Exhaust passage 16 Three-way catalyst 18 Spark plug 20 Ignition device 21 Control device 22 Air flow sensor 23 Rotation speed sensor 24 Cooling water temperature sensor 27 Throttle valve opening sensor 29 Idle control valve

Claims (2)

[Claims] 1. A means for detecting an operating condition, a means for calculating a basic ignition timing from the operating condition, and a means for calculating a basic retardation amount of the ignition timing necessary for activation of a catalyst from a cooling water temperature at the start. Means for calculating the correction value of the retard angle amount from the opening degree of the idle control valve that bypasses the intake throttle valve and increases the amount of air, and means for calculating the correction value of the retard angle amount according to the elapsed time after the start. And a means for calculating the idle retard amount by correcting the basic retard amount based on both of these correction values, and a means for correcting the basic ignition timing based on the idle retard amount. A characteristic ignition timing control device for an internal combustion engine. 2. A correction value calculation means based on the opening of the idle control valve outputs a correction value such that the retard amount becomes zero when the opening of the idle control valve is near the maximum value. The ignition timing control device for an internal combustion engine according to claim 1.