JPH11107824A - Controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent engine stalling caused by external load fluctuation or the like during fuel return by mitigating a torque shock following fuel cutting or returning during engine speed reduction. SOLUTION: When an engine speed ne is 2000 rpm or higher and an idle flag xidl is set up, a fuel cut flag xzcut is set up and a fuel reduction correction coefficient ccut is gradually reduced toward 0% (fuel cut). Also, when the flag xzcut is set up, an ignition time delay amount thtrec is set to, for example 5 deg. CA at a first stage, and an intake amount reduction correcting value cerec is set to, for example 5%. Then, when an engine speed ne is decreased to 1500 rpm or lower for example, the coefficient ccut is returned to 100% (fuel return) directly and, after delay amount thtrec is increased more to a delay side, for example 10 deg. Ca directly, it is returned gradually to an advance side, and the correction value cerec is returned gradually to 0%. Further, when re-acceleration is made before fuel return, the delay amount thtrec is gradually returned from the first stage to the advance side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device and, more particularly, to an engine control device for reducing a torque shock accompanying a fuel cut and a return when the engine is decelerated.

[0002]

2. Description of the Related Art When the engine speed is relatively high (for example, 2000 rpm or more), the throttle is fully closed and the engine is decelerated, fuel is cut off, and the engine speed is reduced from the state to a set speed (for example, 1500 rpm). Conventionally, when the fuel supply is lowered, the fuel supply is restored. Since a torque shock occurs at the time of fuel cut and return, for example, Japanese Patent Publication No. 58-20
As described in Japanese Patent Publication No. 374, the fuel is gradually reduced at the time of fuel cut and the fuel is gradually increased at the time of return, so that the change in fuel amount at the time of fuel cut and return is smoothed, and torque shock is reduced. Such a configuration is conventionally known.

[0003]

When returning from a fuel cut during deceleration, the engine speed is at a considerably low level and the air-fuel ratio is lean, so that engine stall due to misfire is likely to occur. In particular, engine stall is likely to occur particularly when there is a change in conditions such as the clutch being disengaged at the time of return and a change in external load or the like occurs. Then, as in the conventional control described above, to reduce the torque shock accompanying the fuel cut and return during deceleration by smoothing the change in the fuel amount,
The recovery of the air-fuel ratio at the time of return is further delayed, and the concern of engine stall due to external load fluctuation or the like becomes even greater.

Accordingly, it is an object of the present invention to prevent the engine from stalling due to an external load change or the like at the time of fuel return while alleviating the torque shock accompanying the fuel cut and return at the time of engine deceleration.

[0005]

According to a first aspect of the present invention, there is provided a control apparatus for an engine, comprising: a speed detecting means for detecting an engine speed; a deceleration detecting means for detecting a decelerating operation of the engine;
Deceleration control means for receiving the outputs of the rotation speed detection means and the deceleration detection means, and gradually controlling the air-fuel ratio of the air-fuel mixture supplied to the engine when the engine is decelerated from a state where the engine speed is relatively high, toward the fuel lean side; When the engine speed drops to a predetermined speed while the engine is decelerated in the deceleration lean control state, the air-fuel ratio is returned to the original air-fuel ratio at a stretch, and other control parameters contributing to the increase in the engine torque are gradually reduced. A deceleration / return control means for controlling in a torque increasing direction is provided. In this case, at the time of engine deceleration from a state where the engine speed is relatively high,
The torque shock is reduced by gradually controlling the air-fuel ratio to the lean side. Further, when the engine speed decreases in a deceleration state, the air-fuel ratio quickly returns to the original air-fuel ratio, thereby preventing engine stall due to external load fluctuation and the like, and controlling parameters other than the air-fuel ratio. By gradually controlling the torque in the increasing direction, the torque change becomes smooth, and the shock is reduced.

According to a second aspect of the present invention, there is provided an engine control device for detecting an engine speed, a speed detecting device for detecting a deceleration operation of the engine, and an output of the speed detecting device and the deceleration detecting device. When the engine is decelerated from a state where the engine speed is relatively high, the fuel supplied to the engine is gradually reduced to cut the fuel, and deceleration control means for delaying the ignition timing is provided. When the engine speed drops to a predetermined speed while the engine is decelerating in this state, the fuel is increased at a rate of change greater than the rate of change of the fuel supply at the start of fuel cut, and fuel is returned. And a deceleration and return control means for advancing the angle. In this case, when the engine is decelerated from a state where the engine speed is relatively high, the torque is reduced by gradually decreasing the amount of fuel. In addition, when the engine speed decreases in a deceleration state, the fuel is rapidly increased to prevent engine stall due to external load fluctuation and the like, and to gradually advance the ignition timing once retarded at the time of fuel cut. By squaring, the torque change becomes smooth, and the shock is reduced.

According to a third aspect of the present invention, in the engine control apparatus according to the second aspect, the ignition timing is suddenly retarded substantially at the same time as the fuel reduction. When the fuel reduction is started, the engine speed is relatively high, so there is no concern about engine stall even if an external load change or the like occurs due to a situation change such as disengagement of the clutch. Therefore, the ignition timing may be retarded at a stretch almost at the same time as the fuel reduction.

According to a fourth aspect of the present invention, there is provided the engine control apparatus according to the second or third aspect, wherein the ignition timing is further retarded when the fuel reduction and the cut are continued for a predetermined time. . When the ignition timing is retarded in two stages in this manner, the ignition timing retard amount is small for a while after the fuel cut, and the torque shock is alleviated while ensuring reacceleration when reacceleration is performed during that time. I can do it. The engine control device according to claim 5 is
The engine control device according to claim 2 or 3,
At about the same time as the fuel increase, the ignition timing is once further retarded. By doing so, it is possible to alleviate the torque shock at the time of fuel return while ensuring re-acceleration during fuel cut.

According to a sixth aspect of the present invention, there is provided the engine control apparatus according to the second, third, fourth, or fifth aspect of the present invention, wherein the vehicle exits the deceleration operation and starts re-acceleration from the state of fuel reduction and cut. At that time, the ignition timing is gradually advanced. By doing this,
The torque shock during re-acceleration can be reduced.

The engine control device according to a seventh aspect of the present invention is the engine control device according to the second, third, fourth, fifth or sixth aspect, wherein the intake air amount is reduced at a stroke substantially simultaneously with the fuel reduction, and the ignition timing is gradually increased. The intake amount is gradually increased simultaneously with the advance angle. The torque fluctuation due to the adjustment of the ignition timing is smaller than the torque fluctuation due to the fuel adjustment.
The amount of fluctuation is small and the adjustment range is narrow. For this reason, it is effective to adjust the torque by gradually increasing the intake air amount in addition to the gradual retardation of the ignition timing at the time of fuel return, whereby the torque shock at the time of fuel return can be reduced. And
The intake air amount is reduced almost at the same time when the deceleration fuel cut is started, so that the intake air amount can be increased at the time of fuel return. When entering the deceleration fuel cut, it will be in a semi-misfire state,
Although there is no great difference in the amount of intake air even if it is reduced gradually or at a stretch, it is easier to reduce the amount at once.

[0011]

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

FIG. 1 shows a schematic structure of an engine to which the present invention is applied. In this figure, reference numeral 1 denotes an engine body having a cylinder. An intake port 3 opened and closed by an intake valve and an exhaust port 4 opened and closed by an exhaust valve are opened in a combustion chamber 2 of the cylinder. A spark plug 18 is disposed at the center of the vehicle.

An intake passage 5 is connected to the intake port 3, and an exhaust passage 13 is connected to the exhaust port 4.
The intake passage 5 is provided with an air cleaner 6, an air flow sensor 7, a throttle valve 8, and a surge tank 9 in this order from the upstream side, and an injector (fuel injection valve) 10 for injecting fuel near the intake port 5. Is provided. Further, an ISC passage 11 that bypasses the throttle valve 8 is provided.
Is provided with an ISC valve 12 for adjusting the air flow rate in the passage 11 for controlling the idle speed. On the other hand, an O ₂ sensor 14, a catalyst device 15, and the like are provided in the exhaust passage 13. Further, an idle switch 16 is provided in the intake passage 5, and a crank angle sensor 17 and a water temperature sensor 19 are provided in the engine body 1.

A fuel system for supplying fuel to the injector 10 includes a fuel tank 20, a fuel pump 21, a fuel supply passage 22, and a return passage 23. The fuel pump 21 passes through the fuel supply passage 22 from the fuel tank 20. Fuel is sent to the injector 10. The fuel filter 2 is provided in the fuel supply passage 22.
4 are interposed. The return passage 23 is provided with a pressure regulator 25 for adjusting the fuel pressure in accordance with the intake pressure.

An evaporative fuel supply system is provided for supplying the evaporative fuel generated in the fuel tank 20 to the intake side. The evaporative fuel supply system includes a purge passage 30. The purge passage 30 has an upstream end at the fuel tank 20.
And a downstream end thereof is connected to the surge tank 9 of the intake passage 5. A canister 31 for adsorbing the evaporated fuel is provided in the middle of the purge passage 30.
2 are connected.

In the purge passage 30 between the fuel tank 20 and the canister 31, an open / close valve (hereinafter, referred to as a TPCV valve) 34 composed of a solenoid valve is provided in parallel with the check valve 33. The air release passage 32 has an air filter 35 and a check valve 3.
6 and an opening / closing valve (hereinafter, referred to as a CDCV valve) 37 composed of a solenoid valve. TPCV valve 34 and CDCV valve 37
Constitutes a passage opening / closing means which enables opening / closing of the purge passage 30 and opening / closing of the atmosphere opening portion between the fuel tank 20 and the intake passage 5 respectively.

In the purge passage 30 between the canister 31 and the surge tank 9, there is provided a purge valve 38 comprising a duty solenoid valve for adjusting a supply amount (purge amount) of a purge gas containing evaporated fuel. Further, the fuel vapor supply system is provided with a fuel tank pressure sensor (hereinafter referred to as an FTP sensor) 39 as pressure detecting means for detecting the pressure of the purge passage 30 on the fuel tank 20 side.

The engine control unit 40, the air flow meter 7, O ₂ sensor 14, the idle switch 16 receives a signal from the speed sensor 17, FTP sensor 39, the injector 10, the ignition plug 18, ISC valve 12, etc. Control.

The engine control unit 40 controls deceleration fuel cut and return. Therefore, the engine control unit 40 includes the sensors 7, 14, 16,
In addition to the signals from the switches 17 and 39, a neutral state detection signal is input from a neutral switch (inhibitor switch) 41, and a brake pedal depression detection signal is input from a brake switch.

FIG. 2 is a time chart showing control at the time of deceleration fuel cut and return.

In this control, the idle switch 16
When the throttle is fully closed at N (ON), the idle flag xidl is set (xidl = 1). When the idling flag xidl is set in a state where the engine speed ne is relatively high, for example, 2000 rpm or more, the fuel cut flag xzcut is set (xzcut = 1), and the fuel injection amount reduction correction coefficient ccut from the injector 10 is reduced by the fuel cut. Is gradually reduced at a predetermined change rate (for example, 5%), and when the value of ccut becomes equal to or less than a predetermined value (for example, 30%), ccut is set to 0% (fuel cut).

The final fuel injection amount is obtained by multiplying the required fuel injection amount based on the intake charging efficiency by the reduction correction coefficient ccut.

When the idle flag xidl is raised and the fuel cut flag xzcut is raised, the ignition timing retard amount thtrec for returning the fuel is reduced to, for example, 5 ° C.
A (crank angle) is set. At this time, the intake air amount decrease correction value cerec is set to a value such as 5% at a stretch. Then, the intake air amount (qis) of the ISC passage 11 set by a table value based on the engine water temperature.
c) is corrected by the decrease correction value cerec.

From this state, the idle flag x
When the engine speed drops while the idl is standing, and becomes lower than the fuel return speed, for example, 1500 rpm,
The fuel cut flag xzcut becomes zero (xzcut = 0), and the reduction correction coefficient ccut is returned to 100% at a stretch (fuel return). Note that the weight loss correction coefficient c at the time of this return
The change in cut is performed at a rate of change that is at least greater than the rate of change at the start of fuel cut.

When the fuel cut flag xzcut becomes zero, at the same time, the ignition timing retard amount thtrec is once further increased to, for example, 10 ° CA at once on the retard side, and then, for example, by 1 ° CA. It is gradually returned to the advance side at a predetermined change rate. When the fuel cut flag xzcut becomes zero, the intake air amount decrease correction value cerec is gradually returned to 0% at a predetermined change rate of, for example, 0.5%.

In the case where the fuel cut flag xzcut is set and the fuel is cut and the fuel is reaccelerated until the fuel is returned, the control is performed as shown by a broken line in FIG. 2, and the idle flag xidl is set to zero. Then, the fuel cut flag xzcut becomes zero, and at that time the reduction correction coefficient cc
ut is returned to 100%, and the fuel is returned. At the same time, the retard amount thtrec of the ignition timing is gradually returned to the advance side at a rate of change, for example, 2 CA, which has a larger inclination than that at the time of the return when the throttle is fully closed. Also, at the same time, the intake air amount decrease correction value cerec is gradually returned to 0% at a rate of change, for example, 1.0%, which has a larger inclination than that at the time of return when the throttle is fully closed.

In the neutral state, the torque shock is not transmitted to the vehicle body. Therefore, when the neutral state detection signal is input, the fuel injection amount decrease correction coefficient ccut is immediately set to 0% and the fuel is cut. In the neutral state, the ignition timing retard amount thtrec is fixed at 0 CA.

Further, in the fuel cut at the time of deceleration of the engine with the brake depressed, the decrease correction coefficient ccut is gradually reduced at a higher change rate such as 10%.

FIGS. 3 to 6 are flowcharts of this control.

First, FIG. 3 is a flowchart of the fuel cut zone determination. First, at step 101, it is determined whether or not the idle flag xidl is set. And
If the flag xidl is on, step S102
To see if the engine speed ne is higher than 2000 rpm, and if the engine speed ne is higher than 2000 rpm, it is determined that the fuel cut zone has been reached, and step S
At 103, the fuel cut flag xzcut is set, and the routine returns.

If it is determined in step S102 that the engine speed ne is not more than 2000 rpm, the flow proceeds to step S104.
It is checked whether the fuel cut flag xzcut is set. If the fuel cut flag xzcut is set, it means that the fuel is being cut. In step S105, the fuel return condition is determined based on whether the engine speed ne is still higher than 1500 rpm. Is determined. If the engine speed ne is higher than 1500 rpm, the fuel return condition is not satisfied, and the process returns to step S103, and returns with the fuel cut flag xzcut set.

If the engine speed ne becomes 1500 rpm or less in step S105, the fuel return condition is satisfied, and the fuel cut flag xzcut is lowered in step S106.

FIG. 4 is a flowchart of the fuel injection control. First, in step S201, the idle flag xid is set.
See if l is standing. If the idle flag xidl is not set, the setting of the weight reduction coefficient ccut is set to 100% in step S202. In step 203, the required fuel injection amount (pulse width) obtained by multiplying the charging efficiency ce by the coefficient α is corrected by ccut to obtain the final fuel injection pulse width te, and injection is performed.

When the idling flag xidl is set in step S201, it is checked in step S204 whether the fuel cut flag xzcut is set.
If the fuel cut flag xzcut is not set, it is determined that the fuel cell is not in the fuel cut zone.
In 02, the setting of the weight reduction correction coefficient ccut is also set to 100%.

When the fuel cut flag xzcut is set in step S204, the fuel cut zone is set, and the fuel cut routine of steps S205 to S210 is started. Then, the weight loss correction coefficient ccut is set to 30.
%, So that it is gradually reduced to step S2.
05, it is determined whether the weight loss correction coefficient ccut is greater than 30%. If the weight loss correction coefficient ccut is higher than 30%, it is determined in step S206 whether the neutral flag xnl is set, and the neutral flag xnl is determined.
If is not set, then it is checked in step S207 whether the brake depression flag xbrk is set. And when the brake depression flag xbrk is on,
In step S208, the weight reduction coefficient ccut is reduced by 10%.

If it is determined in step S207 that the brake depression flag xbrk has not been set, the flow proceeds to step S209.
Reduce the weight loss correction coefficient ccut by 5%.

If the neutral flag xnl is set in step S206, the reduction correction coefficient ccut is immediately set to 0% in step S210.

Also, in step S205, the weight reduction correction coefficient c
When cut becomes 30% or less, it is wasteful to inject the fuel, and the weight reduction correction coefficient ccu is determined in step S210.
Let t be 0%.

Thus, in steps S205 to S210, the reduction correction coefficient ccut is set, and in step 203, the final fuel injection pulse width te is obtained, and the reduction injection or injection cut is performed.

After the fuel is cut in the routine of steps S205 to S210, if the fuel cut flag xzcut falls in step S204, it means that the fuel is to be restored, and the setting of the reduction correction coefficient ccut is immediately performed in step S202. Return to%. And step 20
In step 3, the final fuel injection pulse width te is obtained and the fuel is injected.

If the fuel cut flag xzcut has not been raised from the beginning in step S204, the process directly proceeds to step S202, where the reduction correction coefficient ccut is set to 10
In step 203, the final fuel injection pulse width te
And inject.

FIG. 5 is a flowchart of the ignition timing control. When started, it is determined in step S301 whether the neutral flag xnl is set. And
If the neutral flag xnl is not set, the process proceeds to step S302, and it is determined whether the idle flag xidl is set. If the idle flag xidl is set, the fuel cut flag xzc is set at step S303.
See if ut is standing. If the fuel cut flag xzcut is on, step S30
In step 4, the ignition timing retard amount thtrec for fuel return is set to 5 CA. Then, after the previous value xzcutp of the fuel cut flag is set to 1 in step S305, in step S306, the final ignition timing thtig is set as a value obtained by delaying the basic ignition timing obtained from the map of the engine speed ne and the charged amount ce by thtrec. Set and perform ignition.

If it is determined in step S303 that the fuel cut flag xzcut is not set, the flow proceeds to step S307.
To see if the previous value xzcutp of the fuel cut flag is 1 and check the previous value xzcutp of the fuel cut flag.
Is 1, this means that the vehicle has passed the fuel cut zone this time, and in step S308, the retard amount thtrec is set to 10 CA. Then, at step S309, the previous value xzcutp of the fuel cut flag is set to 0, and at step S3
At 06, the final ignition timing thtig is set, and ignition is performed.

If the previous value xzcutp of the fuel cut flag is 0 in step S307, step S31
At 0, the retard amount thtrec becomes 1 CA until it reaches 0 CA
And the final ignition timing tht is determined in step S306.
ig is set and ignition is performed.

The fact that the idling flag xidl is not set in step S302 means that the vehicle is running at the time of normal driving or re-acceleration from the fuel cut.
To reduce the retard amount thtrec by 2 CA until it reaches 0 CA. In the case of normal running, the retard amount tht
Since rec is originally 0 ゜ CA, step S311 is practically bypassed. Then, step S30
In step 6, the final ignition timing thtig is set, and ignition is performed.

FIG. 6 is a flowchart of the ISC control. When started, it is checked in step S401 whether the neutral flag xnl is set. If the neutral flag xnl is not set, the process proceeds to step S402, and it is determined whether the idle flag xidl is set. If the idle flag xidl is set, the fuel cut flag xzcu is set in step S403.
See if t is standing. If the fuel cut flag xzcut is on, step S404
To set the intake air amount decrease correction value cerec by ISC to 5%. Then, in step S405, the engine coolant temperature t
ISC basic quantity cebs as table value based on hw
e is calculated, and the engine speed ne is set to a value obtained by correcting the basic amount cebse by the reduction correction value cerec in step S406.
And the coefficient α to obtain the final intake air amount qisc of the ISC, and control the ISC valve.

If the fuel cut flag xzcut is not set in step S403, it means that the vehicle has passed the fuel cut zone, and the weight reduction correction value cerec is reduced by 0.5% in step S407. Then, in step S405, the basic amount cbsse of ISC is obtained, and in step S406, the final intake air amount qisc of ISC is obtained.
Control the SC valve.

The fact that the idle flag xidl is not set in step S402 means that the vehicle is running at the time of normal running or re-acceleration from the fuel cut.
To reduce the reduction correction value cerec by 1.0% until it becomes 0%. In the case of normal running, the weight reduction correction value ce
Since rec is originally 0%, step S408 is effectively bypassed. Then, in step S405, the basic amount of cscse of ISC is obtained, and in step S406, the final intake amount qisc of ISC is obtained, and the ISC valve is controlled.

In the above example, the second stage of the ignition timing is retarded almost simultaneously with the return of the fuel from the deceleration fuel cut. However, if the fuel reduction and the cut are continued for a predetermined period of time, The second stage retardation may be automatically performed.

[0050]

According to the present invention, while reducing the torque shock accompanying the fuel cut and return at the time of engine deceleration,
It is possible to prevent engine stall due to external load fluctuation or the like at the time of fuel return.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an engine to which the present invention is applied.

FIG. 2 is a time chart of control at the time of deceleration fuel cut and return in the embodiment.

FIG. 3 is a flowchart of a fuel cut zone determination in the embodiment.

FIG. 4 is a flowchart of fuel injection control in the embodiment.

FIG. 5 is a flowchart of ignition timing control in the embodiment.

FIG. 6 is a flowchart of ISC control in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 10 Injector 11 ISC passage 12 ISC valve 16 Idle switch 17 Crank angle sensor 18 Spark plug 19 Water temperature sensor 40 Engine control unit

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02P 5/15 F02P 5/15 F (72) Inventor Hiroyuki Kusunoki 3-1, Fuchi-cho, Fuchu-cho, Aki-gun, Hiroshima Mazda

Claims (7)

[Claims] 1. A rotational speed detecting means for detecting an engine rotational speed, a deceleration detecting means for detecting a decelerating operation of an engine,
Deceleration control means for receiving the outputs of the rotation speed detection means and the deceleration detection means, and gradually controlling the air-fuel ratio of the air-fuel mixture supplied to the engine when the engine is decelerated from a state where the engine speed is relatively high, toward the fuel lean side; When the engine speed drops to a predetermined speed while the engine is decelerated in the deceleration lean control state, the air-fuel ratio is returned to the original air-fuel ratio at a stretch, and other control parameters contributing to the increase in the engine torque are gradually reduced. An engine control device comprising: a deceleration / return control means for controlling in a torque increasing direction. 2. A rotational speed detecting means for detecting an engine rotational speed, a deceleration detecting means for detecting a decelerating operation of the engine,
In response to the outputs of the rotation speed detection means and the deceleration detection means, the amount of fuel supplied to the engine is gradually reduced when the engine is decelerated from a state where the engine speed is relatively high, so that the fuel is cut and the ignition timing is retarded. The deceleration control means increases the fuel at a rate of change larger than the rate of change of the fuel supply amount at the start of the fuel cut when the engine speed drops to a predetermined speed while the engine is decelerated with the fuel cut at the time of engine deceleration. And a deceleration / return control unit for gradually advancing the ignition timing while returning fuel. 3. The engine control device according to claim 2, wherein the deceleration control means delays the ignition timing at a stretch substantially simultaneously with the fuel reduction. 4. The engine control device according to claim 2, wherein the ignition timing is further retarded by the deceleration control means if the fuel reduction and the cut are continued for a predetermined time. 5. The engine control device according to claim 2, wherein the ignition timing is once further retarded substantially simultaneously with the fuel increase by the deceleration / return control means. 6. A re-acceleration control means for gradually advancing the ignition timing at the time of re-acceleration after deceleration operation from the state of fuel reduction and cut-off by said deceleration control means. , 3, 4 or 5. 7. The deceleration control means reduces the intake air amount at a stroke substantially at the same time as the fuel reduction, and the deceleration return control means gradually increases the intake air amount simultaneously with the gradual advancement of the ignition timing. 7. The control device for an engine according to 4, 5, or 6.