JP3407648B2 - 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, in an in-cylinder injection type internal combustion engine in which fuel is directly injected into a cylinder, switches the combustion mode of air-fuel mixture between stratified charge combustion and homogeneous charge combustion in accordance with operating conditions and the like. The present invention relates to an internal combustion engine control device with an improved control system for time.

[0002]

2. Description of the Related Art In recent years, the demand for in-cylinder injection engines having the features of low fuel consumption, low exhaust emission and high output has been rapidly increasing. This in-cylinder injection engine injects a small amount of fuel in the compression stroke at the time of low load to perform stratified combustion of the air-fuel mixture (lean operation), and at medium and high loads, increases the fuel injection amount and injects in the intake stroke. To burn the mixture homogeneously (rich operation). Further, since the in-cylinder injection engine produces a larger amount of NOx than the intake port injection engine, NOx is discharged to the exhaust pipe.
Storage type lean NOx catalysts are often installed. This lean NOx catalyst adsorbs NOx in the exhaust during lean operation in which the oxygen concentration in the exhaust is high, and reduces and purifies the adsorbed NOx when the air-fuel ratio is switched to rich and the oxygen concentration in the exhaust decreases. And then release. Therefore, lean NO
In order to maintain the NOx purification performance of the x catalyst, it is necessary to occasionally switch to rich operation (homogeneous combustion) during lean operation (stratified combustion).

Furthermore, during lean operation, the negative pressure in the intake pipe is small, and the braking boosting effect of the brake booster that uses that negative pressure as a drive source is reduced, so during lean operation (stratified combustion), it sometimes becomes rich. It is necessary to switch to operation (homogeneous combustion) and increase the intake pipe negative pressure to secure the negative pressure in the brake booster.

For the above reasons, in the cylinder injection engine, the combustion method is appropriately switched between stratified combustion and homogeneous combustion during operation. However, in FIG.
As shown in Fig. 3, in the conventional cylinder injection engine, there is a region where combustion becomes unstable between the stable combustion regions of both stratified charge combustion and homogeneous combustion. pass. For this reason, at the time of switching the combustion system, depending on the load, misfire or torque shock may occur when passing through the unstable combustion region.

As a countermeasure when switching the combustion system, Japanese Patent Laid-Open No. 7-187
In Japanese Patent No. 166913, the target air-fuel ratio is gradually changed at the time of switching the combustion system to prevent a torque shock at the time of switching the combustion system.

[0006]

However, even in the technique disclosed in the above publication, the situation of passing through the unstable combustion region at the time of switching the combustion system does not change, so that misfire may occur.

Further, in the conventional combustion system switching control, when the combustion system is switched, the exhaust gas recirculation amount (EGR amount) recirculated to the intake system and the fuel evaporative gas amount (purge amount) purged to the intake system are also The air system (throttle opening, swirl flow intensity), fuel system and ignition system are switched simultaneously. However, introducing EGR gas or fuel evaporative gas into the intake system at the time of switching the combustion system, which tends to make combustion unstable, results in making combustion more and more unstable. Moreover, even if the opening degree of the EGR valve (EGR amount) or the opening degree of the purge valve (purge amount) is accurately controlled at the time of switching the combustion system, the air-fuel ratio of the EGR gas and the purge gas varies depending on the operating state at that time. Therefore, when switching the combustion method, EG
If the amount of R or the amount of purge is large, the air-fuel ratio of the air-fuel mixture at the time of switching the combustion system cannot be accurately controlled, which also causes instability of combustion and causes misfire or torque shock.

The present invention has been made in consideration of such circumstances, and therefore an object thereof is to stabilize the combustion at the time of switching the combustion system and to prevent the occurrence of misfire and torque shock. An object of the present invention is to provide an internal combustion engine control device that can be used.

[0009]

In order to achieve the above object, in the internal combustion engine control apparatus according to the first aspect of the present invention, the combustion system switching control means includes the exhaust gas recirculation amount and the purge when the combustion system switching request occurs. The combustion method is switched after controlling so that at least one of the amounts is reduced or made zero (hereinafter referred to as "reduction control"). With this configuration, it is possible to reduce or eliminate the influence of the exhaust gas recirculation gas and the fuel evaporative gas on the combustion state at the time of switching the combustion system, and improve the combustion stability before switching the combustion system. In addition, if the exhaust gas recirculation amount and the purge amount are reduced or made zero, (b) in FIG.
As shown in FIG. 2, the stable combustion regions of both stratified combustion and homogeneous combustion are expanded to overlap each other, and the unstable combustion region as shown in FIG. 2A is eliminated. Therefore, in the present invention, it is possible to switch the combustion method without passing through the unstable combustion region while increasing the combustion stability by the reduction control at the time of switching the combustion method, and the occurrence of misfire or torque shock at the time of switching the combustion method. Can be prevented.

In this case, there is a time delay from the start of the reduction control of the exhaust gas recirculation amount and the purge amount to the actual stabilization of combustion. Further, there is a time delay in switching the air system as compared with switching between the fuel system and the ignition system. In consideration of these points, in the invention according to claim 1 , the air system (throttle control means and swirl flow control means) is set after a predetermined delay period has elapsed since the reduction control was started when a combustion system switching request was made. Start the control to switch the control amount of the fuel cell according to the combustion system of the switching destination, and then switch the control amount of the fuel system and the ignition system according to the combustion system of the switching destination.
There is . In this way, it is possible to prevent switching of the combustion system (switching of the air system) from starting before the effect of combustion stabilization by the weight reduction control appears, and at the appropriate timing in accordance with the delay of the air system. The control amount of the fuel system and the ignition system can be switched by, and the misfire / torque shock prevention effect at the time of switching the combustion system can be further enhanced.

Further, as described in claim 2 , the control amounts of the fuel system and the ignition system are switched in accordance with the combustion system of the switching destination, or at the same time or after the switching, the exhaust gas recirculation means and / or the fuel evaporative gas purge means are changed. The control may be switched from the reduction control to a normal control according to the combustion method after switching. In other words, the switching of the combustion system is completed by switching between the fuel system and the ignition system, and the combustion state stabilizes.
After that, even if the control of the exhaust gas recirculation means or the fuel evaporative gas purge means is switched to the normal control, the combustion does not become unstable.

By the way, when a decrease or zero exhaust gas recirculation amount and the purge amount, for changing the output torque of the internal combustion engine, as claimed in claim 3, during the decrease control, the ignition system,
At least one control amount of the fuel system and the variable valve control means may be corrected by the torque correction means in the direction of suppressing the torque fluctuation due to the reduction control. With this configuration, it is possible to suppress torque fluctuation due to the reduction control at the time of switching the combustion system, and further improve drivability.

In this case, the torque change due to the reduction control is
Since the larger weight loss of the exhaust gas recirculation amount and the purge amount increases, as claimed in claim 4, it may be set the torque correction amount in accordance with weight loss caused by loss control. With this configuration, it is possible to accurately set an appropriate torque correction amount that suppresses a torque change amount due to the reduction control.

Further, the time required from the start of the reduction control until the combustion is actually stabilized becomes shorter as the exhaust gas recirculation amount or the purge amount before the reduction control is started becomes shorter.
5 , the delay period from the start of the reduction control to the start of the switching of the air system may be set based on at least one of the exhaust gas recirculation amount and the purge amount before the start of the reduction control. In this way, the delay period can be optimized in response to the change in the time required for the combustion to stabilize depending on the exhaust gas recirculation amount and the purge amount before the reduction control is started.

Alternatively, as in claim 6 , when at least one of the exhaust gas recirculation amount and the purge amount before starting the reduction control is smaller than a predetermined value, the delay period is set to zero or short, or the reduction control is executed. Instead, the control amount of the air system may be switched. That is, when the exhaust gas recirculation amount and the purge amount are already small before the reduction control is performed,
Since it can be estimated that the combustion is stable to some extent, the delay method is set to zero or short, or the combustion method is switched (air system switching) without reducing control.
Even if you start, there is no misfire or large torque shock. As a result, when the combustion is in a stable state to some extent, it is possible to quickly switch the combustion system in response to the combustion system switching request.

According to a seventh aspect of the invention, the acceleration / deceleration of the vehicle is determined by the acceleration / deceleration determining means, and when the acceleration / deceleration is larger than a predetermined value, the delay period is set to zero or short as in the sixth aspect. Alternatively, the control amount of the air system may be switched without executing the reduction control.
In other words, when the driver requests sudden acceleration or deceleration and the acceleration or deceleration becomes greater than the predetermined value, the responsiveness is emphasized and the combustion system is switched swiftly. It is possible to eliminate the feeling and feeling of idling when decelerating.

[0017] In this case, as according to claim 8, the accelerator opening, the throttle opening, the amount required fuel injection, may be possible to determine the acceleration on the basis of at least one change in the vehicle speed. In either case, since the acceleration / deceleration can be determined by diverting the output information of the sensor generally provided in the vehicle or the calculated value of the engine control computer, it is necessary to newly provide an acceleration sensor for detecting the acceleration / deceleration. Without
It is possible to meet the demands for reduction of the number of parts and cost reduction.

Further, as described in claim 9 , the operating region of the internal combustion engine is determined by the operating region determining means, and when the operating region is within the predetermined operating region, the delay period is set to zero or short, or the amount is reduced. The control amount of the air system may be switched without executing the control. That is, drivability can be further improved by promptly switching the combustion system in response to the combustion system switching request in an operating region where torque shock is not felt when switching the combustion system.

In this case, the operating region where torque shock is not felt is the high load region or the low load region,
These can be determined from the accelerator opening and the required fuel injection amount. Therefore, the operating range in which the combustion mode switching is promptly switched in response to the combustion mode switching request is, as in claim 10 , a region (high load region) in which the accelerator opening or the required fuel injection amount is equal to or more than a predetermined value, or the accelerator region. The opening degree or the required fuel injection amount may be set in at least one of a region (low load region) where the amount is equal to or less than a predetermined value. In this way, it is possible to easily determine the operating region in which the torque shock is not felt when switching the combustion system from the accelerator opening or the required fuel injection amount.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION << Embodiment (1) >> An embodiment (1) of the present invention will be described below with reference to FIGS.
First, the schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of a cylinder injection type engine 11 which is a cylinder injection type internal combustion engine, and a step motor 14 (throttle control means) is provided on the downstream side of the air cleaner 13. A throttle valve 15 whose opening is adjusted is provided. The step motor 14 is driven based on an output signal from an engine electronic control circuit (hereinafter referred to as “ECU”) 16 to control the opening of the throttle valve 15 (throttle opening). The intake air amount to each cylinder is adjusted in accordance with. A throttle sensor 1 for detecting the throttle opening is provided near the throttle valve 15.
7 is provided.

A surge tank 19 is provided downstream of the throttle valve 15, and an intake manifold 20 for introducing air into each cylinder of the engine 11 is connected to the surge tank 19. Intake manifold 20 for each cylinder
A first intake passage 21 and a second intake passage 22 are formed inside the partition, respectively, and the first intake passage 21 and the second intake passage 22 are formed therein.
Are respectively connected to two intake ports 23 formed in each cylinder of the engine 11.

A swirl control valve 24 (swirl flow control means) is arranged in the second intake passage 22 of each cylinder. The swirl control valve 24 of each cylinder is connected to a step motor 26 via a common shaft 25. By driving the step motor 26 based on the output signal from the ECU 16, the opening degree of the swirl control valve 24 is controlled, and the swirl flow intensity in each cylinder is adjusted according to the opening degree. A swirl control valve sensor 27 that detects the opening degree of the swirl control valve 24 is attached to the step motor 26.

A fuel injection valve 28 for directly injecting fuel into the cylinder is attached to the upper portion of each cylinder of the engine 11. The fuel sent from the fuel tank 43 to the fuel delivery pipe 30 through the fuel pipe 29 is directly injected into the cylinder from the fuel injection valve 28 of each cylinder, and the intake port 23
A mixture is formed by mixing with intake air introduced from.

Further, a spark plug (not shown) is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each spark plug. Further, the cylinder discrimination sensor 32 generates an output pulse when a specific cylinder (for example, the first cylinder) reaches the intake top dead center, and the crank angle sensor 33 causes the engine 11 to operate.
Crankshaft has a constant crank angle (for example, 30 ℃
A) An output pulse is generated each time it rotates. The crank angle and the engine speed are detected by these output pulses, and the cylinder discrimination is performed.

On the other hand, the exhaust gas discharged from each exhaust port 35 of the engine 11 joins into one exhaust pipe 37 via the exhaust manifold 36. In the exhaust pipe 37, a three-way catalyst 38 that purifies the exhaust gas near the stoichiometric air-fuel ratio and a NOx occlusion type lean NOx catalyst 39 are arranged in series. This lean NOx catalyst 39 adsorbs NOx in the exhaust gas during lean operation in which the oxygen concentration in the exhaust gas is high, and when the air-fuel ratio is switched to rich and the oxygen concentration in the exhaust gas decreases,
The adsorbed NOx is reduced and purified and released. This lean N
A NOx concentration sensor (not shown) that detects the NOx concentration in the exhaust gas flowing out from the lean NOx catalyst 39 is installed downstream of the Ox catalyst 39, and the NOx of the lean NOx catalyst 39 estimated from the NOx concentration in the exhaust gas. When the adsorption amount exceeds a predetermined value, the air-fuel ratio is temporarily switched from lean to rich as described later.

Further, between the upstream side of the three-way catalyst 38 of the exhaust pipe 37 and the surge tank 19, an EGR pipe 40 for connecting a part of exhaust gas to the intake system is connected.
An EGR valve 41 (exhaust gas recirculation means) is provided in the middle of the R pipe 40. The opening degree of the EGR valve 41 is controlled based on the output signal from the ECU 16, and the EG
The R amount (exhaust gas recirculation amount) is adjusted. Further, the accelerator pedal 18 has an accelerator sensor 4 for detecting an accelerator opening degree.
Two are provided.

A brake booster (not shown) is connected to the surge tank 19 so that the intake pipe negative pressure is introduced into the brake booster. A negative pressure sensor (not shown) for detecting an internal negative pressure is attached to this brake booster, and when the negative pressure in the brake booster falls below a predetermined value, the air-fuel ratio is temporarily changed as described later. Switched from lean to rich.

Further, a purge pipe 45 for purging (releasing) the adsorbed fuel evaporative gas to the intake system is connected between the canister 44 for adsorbing the evaporative gas in the fuel tank 43 and the intake pipe 12. A purge valve 46 (fuel evaporative gas purge means) is provided in the middle of the pipe 45.
The opening of the purge valve 46 is controlled based on the output signal from the ECU 16, and the amount of fuel evaporative gas purged into the intake system (purge amount) is adjusted according to the opening.

The output signals of the various sensors described above are sent to the ECU.
16 is input. The ECU 16 is mainly composed of a microcomputer, and based on various sensor outputs in accordance with a control program stored in a built-in ROM (storage medium), the step motors 14 and 26, the fuel injection valve 28, the spark plug, EGR valve 41, purge valve 4
6 controls the operation.

By executing the routines shown in FIGS. 3 and 4 and FIGS. 6 to 8 during engine operation, the ECU 16 executes the stratification combustion (lean operation) and the homogeneous combustion in accordance with the combustion system switching request. Switching to (rich operation), in stratified charge combustion, a small amount of fuel is injected in the compression stroke to form a partially rich mixture around the spark plug, thereby burning a lean mixture, In the homogeneous combustion, the fuel injection amount is increased so as to be near the stoichiometric air-fuel ratio or slightly richer than the stoichiometric air-fuel ratio, and the fuel is injected in the intake stroke to burn the homogeneous mixture.

When the combustion system is switched, the ECU 16 first controls the EGR amount and the purge amount so as to decrease or to zero as shown in FIG. 9 in order to prevent the occurrence of misfire and torque shock. "Weight control"),
After a lapse of a predetermined delay period from the start of this reduction control, the control for switching the control amount of the air system (throttle opening and swirl control valve opening) according to the combustion system of the switching destination is started, After the lapse of the delay period, the control amounts of the fuel system and the ignition system are switched according to the combustion system of the switching destination, and then, after a predetermined period of time, the EGR amount and the purge amount are changed from the reduction control to the normal control according to the combustion system after the switching. Switch to.

The processing contents of each routine executed by the ECU 16 to carry out these controls will be described below.

[Combustion method switching control main routine] The combustion method switching control main routine shown in FIG. 3 is repeatedly executed at predetermined time intervals or at predetermined crank angle intervals during engine operation, and the combustion method switching control in the claims is called. Play a role as a means. When this routine is started,
First, in step 100, a combustion method switching request determination routine of FIG. 4 described later is executed to determine whether or not there is a combustion method switching request, and in the next step 200, an EGR amount / purge amount control routine of FIG. 6 described later. Is executed and the EGR amount and the purge amount are switched according to the presence / absence of the combustion system switching request.

After that, the routine proceeds to step 300, where an air system control routine shown in FIG. 7 to be described later is executed, and the air system control amount (slot valve opening degree,
The swirl control valve opening) is switched, and the next step 400
Then, the fuel system / ignition system control routine of FIG. 8 to be described later is executed, and the control amount (fuel injection amount, injection timing, ignition timing) of the fuel system / ignition system is switched according to the presence / absence of the combustion system switching request. This main routine ends.

[Combustion method switching request determination routine] FIG.
In the combustion method switching request determination routine (step 100 in FIG. 3) shown in FIG. 3, first, in step 101, it is determined whether or not the combustion method is being switched. If it is determined that the combustion method is being switched, the following steps are performed. This routine ends without performing any processing.

After that, when the combustion system switching request is turned off (released) in step 404 of the fuel system / ignition system control routine shown in FIG. 8 which will be described later, when this routine is started after that, in step 101, the combustion system is switched. It is determined that the switching is not being performed, and the routine proceeds to step 102, where it is determined whether the current combustion method is stratified combustion. This step 10
When it is determined in 2 that the current combustion method is stratified combustion, it is determined in the following steps 103 to 105 whether or not it is necessary to switch to homogeneous combustion as follows.

First, in step 103, it is judged whether or not the load detected from the throttle opening degree, the intake pipe negative pressure, etc. is larger than a predetermined value A. If the load is larger than the predetermined value A, step 109 is executed. Going forward, it is determined that there is a request for switching the combustion method to homogeneous combustion. At this time, as shown in FIG. 5, the determination value A for switching from stratified combustion to homogeneous combustion is provided in order to provide hysteresis in the determination of combustion method switching depending on the load.
And the determination value B for switching from homogeneous combustion to stratified combustion have a relation of A> B, and the magnitude of the switching determination value is switched in the switching direction of the combustion method.

If it is determined in step 103 that the load is less than or equal to the predetermined value A, the flow advances to step 104 to check whether the negative pressure in the brake booster (not shown) has decreased below the predetermined value C. If it is determined that the negative pressure is lower than the predetermined value C, the process proceeds to step 107 and it is determined that there is a request for enrichment. Here, the predetermined value C is set to a negative pressure at which a sufficient braking boosting effect of the brake booster cannot be obtained.

On the other hand, when it is determined in step 104 that the negative pressure in the brake booster is not less than the predetermined value C,
Proceeding to step 105, NOx of the lean NOx catalyst 39
It is determined whether or not the adsorption amount is larger than the predetermined value D. If the NOx adsorption amount is larger than the predetermined value D, the routine proceeds to step 107, where it is determined that there is a request for enrichment. Here, the predetermined value D is set to the NOx adsorption amount at which the NOx concentration in the exhaust gas that has passed through the lean NOx catalyst 39 becomes higher than the predetermined value. When it is determined from these steps 104 and 105 to step 107 that it is determined that there is a request for enrichment, it proceeds to step 109 and it is determined that there is a request for switching the combustion method to homogeneous combustion.

On the other hand, steps 103 to 1 described above
When it is determined to be "NO" in all of 05, it is not necessary to enrich the air-fuel ratio and switch to homogeneous combustion.
Proceeding to step 106, it is determined that there is no enrichment request.

If it is determined in step 102 that the current combustion method is homogeneous combustion, step 1
In step 10, it is determined whether the load is less than or equal to a predetermined value B (see FIG. 5). If the load is less than or equal to the predetermined value B, the process proceeds to step 111, and there is a combustion mode switching request to stratified charge combustion. judge. On the other hand, in step 110, the load is the predetermined value B.
If it is determined that it is larger than the above, it is not necessary to switch to stratified charge combustion, so this routine is ended as it is.

[EGR amount / purge amount control routine] FIG. 6
In the EGR amount / purge amount control routine shown in FIG. 3 (step 200 in FIG. 3), first, at step 201, whether the EGR amount and purge amount are being reduced (whether the EGR / purge reduction amount flag XDEC is ON or not). If it is determined that the weight reduction control is being performed, this routine is terminated without performing the subsequent processing.

After that, when this routine is started, if it is determined in step 201 that the EGR / purge reduction is not in progress, the routine proceeds to step 202, where it is determined whether there is a combustion system switching request (ON). To do. If a combustion system switching request is issued in the combustion system switching request determination routine of FIG. 4, the routine proceeds to the next step 203, where the EGR valve opening E
GR (EGR amount) and purge valve opening PRG (purge amount) are set to preset fixed values KEGR and KPRG, respectively.

Here, the fixed values KEGR and KPRG are set to an opening smaller than the opening before and after the combustion system switching or to a fully closed state. As a result, the EGR amount and the purge amount introduced into the intake system are reduced or set to zero, and the influence of the exhaust gas recirculation gas or the fuel evaporative gas on the combustion state is reduced or eliminated by that amount, and the combustion The state is stabilized. Moreover, when the EGR amount and the purge amount are reduced, as shown in (b) of FIG. 2, stable combustion regions of both stratified combustion and homogeneous combustion are expanded and overlap with each other. The unstable combustion region as shown in () disappears.

Then, in the next step 204, EGR
The purging amount reduction flag XDEC is O which means that the amount control is being performed.
After setting to N, the routine proceeds to step 205, where the count value of the EGR / purge reduction counter CEGR is reset to zero. This EGR / purge reduction counter CEGR is
This is an auto-increment counter that counts up every predetermined time after the start of the GR / purge reduction, and the switching of the air system (throttle valve 15, swirl control valve 24) at the time of switching the combustion system in the air system control routine shown in FIG. 7 described later. Used for timing determination.

Thereafter, when the combustion system switching request is turned off in step 404 of the fuel system / ignition system control routine shown in FIG. 8 which will be described later, when this routine is started thereafter, the combustion system switching request is issued in step 202. When it is determined that there is no such value, the routine proceeds to step 206, where the count value of the EGR / purge reduction counter CEGR is set to a predetermined value EC described later.
After setting to EGR, in the next step 207, in order to determine whether or not it is the proper timing to switch the EGR valve opening degree EGR and the purge valve opening degree PRG to the opening degree according to the combustion method of the switching destination, System / Ignition system switching counter CF
It is determined whether or not the count value of UEL exceeds a predetermined value ECFUEL. Here, the fuel system / ignition system switching counter CFUEL is an auto-increment counter that counts up every predetermined time after the combustion system switching request is turned OFF, and is executed in step 406 of the fuel system / ignition system control routine shown in FIG. 8 described later. , The count value is reset to 0 after the switching between the fuel system and the ignition system is completed.

In step 207, the count value of the fuel system / ignition system switching counter CFUEL is a predetermined value ECFU.
If the timing is less than EL and it is not proper timing to start switching the EGR valve 41 and the purge valve 46, the EGR valve 4
1. The routine ends without switching the purge valve 46.

After that, the fuel system / ignition system switching counter C
When the count value of FUEL exceeds the predetermined value ECFUEL, it is determined that it is the proper timing to start switching the EGR valve 41 and the purge valve 46, and the routine proceeds to step 208, where EG
The R valve opening degree EGR and the purge valve opening degree PRG are set by a map or the like according to the engine speed Ne, the load, the combustion method, etc., and the opening degrees of the EGR valve 41 and the purge valve 46 are changed to the combustion method of the switching destination. The opening is switched to the appropriate degree, and this routine is finished.

[Air System Control Routine] In the air system switching control routine (step 300 in FIG. 3) shown in FIG. 7, first, in step 301, there is a combustion system switching request (O).
N) or not. If a combustion system switching request is issued in the combustion system switching request determination routine of FIG. 4, the process proceeds to the next step 302 to determine whether it is the proper timing to start switching the air system. , EG
It is determined whether or not the count value of the R / purge reduction counter CEGR exceeds a predetermined value ECEGR. Here, the predetermined value ECEGR is set in consideration of the time required from the start of EGR / purge reduction control to the actual start of combustion stabilization, and switching of the air system is started from the start of EGR / purge reduction. Up to the delay time ECEGR (see FIG. 9).

In step 302, when the count value of the EGR / purge reduction counter CEGR is equal to or less than the predetermined value ECEGR and it is not the proper timing to start the air system switching, the air system switching is not started, and the step Thirty
In step 4, the count value of the air system switching counter CAIR is reset to 0, and this routine ends. The air system switching counter CAIR is an auto-increment counter that counts up every predetermined time after the start of the air system switching. The fuel system / ignition system control routine shown in FIG. Used when judging.

Then, in step 302, EGR
The count value of the purge reduction counter CEGR is a predetermined value EC
When it exceeds EGR, it is judged that it is the proper timing to start the switching of the air system, and the routine proceeds to step 303, where the throttle opening TA and the swirl control valve opening S at the time of switching the combustion system are set.
CV is set by a map or the like according to the engine speed Ne, the load, the combustion method, etc., and the air system (slot valve 15,
The swirl control valve 24) is switched according to the combustion system of the switching destination and the engine operating state.

On the other hand, whether the combustion system switching request has been issued in the combustion system switching request determination routine of FIG.
When the combustion system switching request is turned off in step 404 of the fuel system / ignition system control routine shown in FIG. 8 which will be described later, it is determined in step 301 that there is no combustion system switching request, the process proceeds to step 305, and the normal control is performed. The throttle opening TA and the swirl control valve opening SCV at the time are set by a map or the like according to the engine speed Ne, the load, the combustion method, etc., and the throttle opening TA and the swirl control valve opening S are set.
The CV is controlled according to the current combustion system and engine operating condition.

[Fuel System / Ignition System Control Routine] Air system switching control routine shown in FIG. 8 (step 400 in FIG. 3)
First, in step 401, it is determined whether or not there is a combustion system switching request (ON). If a combustion method switching request is issued in the combustion method switching request determination routine of FIG. 4, the process proceeds to the next step 402, and it is determined whether or not it is an appropriate timing to start switching between the fuel system and the ignition system. In order to do so, it is determined whether or not the count value of the air system switching counter CAIR exceeds a predetermined value ECAIR. Here, the predetermined value ECAIR is set to the fuel system / ignition system (fuel injection amount, injection timing, ignition timing) at a timing matched to the delay of the air system in consideration of the switching delay of the air system with respect to the fuel system / ignition system. It is set to switch.

In this step 402, if the count value of the air system switching counter CAIR is less than or equal to the predetermined value ECAIR,
If the timing for starting the switching between the fuel system and the ignition system is not appropriate, the switching between the fuel system and the ignition system is not started, and the routine proceeds to step 406, where the fuel system / ignition system switching counter C
The count value of FUEL is reset to 0, and this routine ends. This fuel system / ignition system switching counter CFU
As described above, EL is used to determine the switching timing of the EGR valve 41 and the purge valve 46 in the EGR amount / purge amount control routine shown in FIG.

Then, in step 402, the count value of the air system switching counter CAIR is set to the predetermined value ECAIR.
When it exceeds, it is judged that it is the proper timing to start the switching of the fuel system and the ignition system, and the routine proceeds to step 403, where the fuel injection amount q and the ignition timing SA according to the combustion system of the switching destination are
The fuel system and the ignition system are switched by setting the map according to the engine speed Ne, the load, the combustion method, and the like. Thereafter, in step 404, the combustion mode switching request is reset to OFF, and in the next step 405, the EGR / purge reduction amount flag XDEC is reset to OFF, and this routine ends.

On the other hand, if the combustion system switching request is not issued in the combustion system switching request determination routine of FIG.
When the combustion system switching request is turned off in step 404, it is determined in step 401 that there is no combustion system switching request, the process proceeds to step 407, and the count value of the fuel system / ignition system switching counter CFUEL is set to a predetermined value ECF.
Set to UEL (time to finish EGR / purge reduction), and in the next step 408, map the fuel injection amount q and ignition timing SA during normal control according to the engine speed Ne, load, combustion method, etc. Then, the routine ends.

Next, the combustion method switching control of the present embodiment (1) will be described in comparison with the conventional combustion method switching control with reference to the time charts of FIGS. 9 and 10. FIGS. 9 and 10 show an example of switching from stratified charge combustion (lean operation) to homogeneous combustion (rich operation) in order to secure a negative pressure in the brake booster or reduce NOx reduction of the lean NOx catalyst 39 during steady operation.

In the conventional combustion system switching control, when a combustion system switching request is issued, as shown in FIG.
Since the valve opening, the purge valve opening, the air system (throttle opening, swirl control valve opening) and the fuel system / ignition system (fuel injection amount, injection timing, ignition timing) are all switched at the same time, ) Will pass through the unstable combustion region. Therefore, depending on the operating region, torque shock or misfire occurs when switching the combustion system.

On the other hand, in the combustion mode switching control of the present embodiment (1), as shown in FIG. 9, when a combustion mode switching request is generated, first, the EGR valve opening degree and the purge valve opening degree are made smaller or smaller. Fully closed to cause EG
Decrease or reduce R amount and purge amount. By this reduction control, the stable combustion regions of both stratified combustion and homogeneous combustion are expanded as shown in FIG. 2B, and the unstable combustion region as shown in FIG. 2A is eliminated. Then, the air system (throttle opening and swirl control valve opening) is switched after a predetermined delay period ECEGR has elapsed from the start of the reduction control, that is, after the combustion state has stabilized as described above. After that, in order to consider the delay of the air system, a predetermined delay period EC
After the AIR, the fuel system / ignition system (fuel injection amount, injection timing, ignition timing) is switched. As a result, the fuel system / ignition system is switched at an appropriate timing according to the delay of the air system. After that, after the elapse of a predetermined period ECFUL,
The EGR valve opening and the purge valve opening are switched from the reduction control to a normal control state according to the combustion method after switching.

As described above, if the combustion system is switched after the EGR amount and the purge amount are reduced or reduced to zero, the influence of the exhaust gas recirculation gas and the fuel evaporative gas on the combustion state can be reduced or eliminated when the combustion system is switched. Thus, the combustion method can be switched after the combustion stability is improved. Moreover, it is possible to switch the combustion method without passing through the unstable combustion region, it is possible to prevent the occurrence of misfire and torque shock at the time of switching the combustion method, and the drivability can be improved.

In the above embodiment (1), both the EGR amount and the purge amount are reduced or set to 0 at the time of switching the combustion system. However, only one of the EGR amount and the purge amount is reduced or set to 0. However, even in this case, it is possible to reduce misfire and torque shock at the time of switching the combustion system.

Further, in the above embodiment (1), when the combustion system is switched, the EGR valve opening and the purge valve opening are changed from the reduction control to the normal control after the elapse of a predetermined period ECFUEL after switching the fuel system and the ignition system. However, the EGR valve opening and the purge valve opening may be switched from the reduction control to the normal control at the same time when the fuel system and the ignition system are switched.

<Embodiment (2)> By the way, if the EGR amount and the purge amount are reduced when the combustion system is switched, the output torque of the engine may change and the drivability may be deteriorated. Therefore, in the embodiment (2) of the present invention, the EC
By executing the torque correction routine shown in FIG. 11 by U16 at every predetermined time or every predetermined crank angle, the torque correction during the EGR / purge reduction control is performed as follows.

In the torque correction routine shown in FIG. 11, first, in step 501, it is determined whether or not the EGR / purge reduction amount is in progress. If it is determined that the EGR / purge reduction amount is in progress, the process proceeds to step 502, It is determined whether or not the initial values of the EGR / purge (EGR valve opening immediately before reduction / purge valve opening) have been stored (XDEC0 = ON). If it is determined in step 502 that the EGR / purge initial value is not stored, the process proceeds to step 503, where the current EGR valve opening EGR (i) [EGR amount] and the purge valve opening PRG (i). ) [Purge amount] is the EGR initial value EGR
0 and the purge initial value PRG0 are stored. Thereafter, in step 504, the EGR / purge initial value stored flag XDEC0 is set to ON, which means stored, and the process proceeds to the next step 505. On the other hand, in step 502, E
When it is determined that the GR / purge initial value has been stored (XDEC0 = ON), the process directly proceeds to step 505.

In step 505, the current EGR is calculated from the EGR / purge initial values EGR0 and PRG0.
The valve opening degree EGR (i) and the purge valve opening degree PRG (i) are subtracted to calculate the reduced amounts ΔEGR and ΔPRG. ΔEGR = EGR0−EGR (i) ΔPRG = PRG0−PRG (i) When only one of the EGR valve 41 and the purge valve 46 is subjected to the reduction control, only the reduction control is required to calculate the reduction amount. .

Then, in the next step 506, EGR
Torque correction is performed in order to suppress torque change due to purge reduction control. In this torque correction, for example, when the torque increases, the ignition timing is retarded to suppress the torque increase. At this time, the retard amount of the ignition timing is reduced by ΔEG.
A map having R and ΔPRG as parameters is searched for and set according to the current reduction amounts ΔEGR and ΔPRG.

FIG. 12 shows an example of a map of the ignition timing retard amount with the reduced amount ΔEGR (ΔPRG) as a parameter.
Generally, the larger the amount of reduction ΔEGR (ΔPRG),
As the torque increase increases and the ignition timing retard amount increases, the torque suppression effect increases.
The map characteristic of the ignition timing retard amount of 2 is ΔEGR (ΔPR
The larger the value of G), the larger the ignition timing retard amount is set. The process of step 506 functions as the torque correction means in the claims. Note that, as in the present embodiment (2), the EGR valve 41 and the purge valve 46
In the case where both of the ignition timing retarding amounts are controlled, the ignition timing retarding amount may be finally calculated from the ignition timing retarding amount obtained from ΔEGR and the ignition timing retarding amount obtained from ΔPRG.
The retard amount of the ignition timing may be comprehensively determined from a two-dimensional map or the like in consideration of both R and ΔPRG.

Thereafter, when this routine is started, if it is determined in step 501 that the EGR / purge reduction is not in progress, the routine proceeds to step 507, where the torque correction is canceled,
The normal ignition timing control according to the combustion method is returned to, and this routine is ended.

An execution example of the torque correction routine of the present embodiment (2) described above will be described with reference to the time chart of FIG. When a combustion mode switching request is issued and EGR / purge reduction control is started, the EGR / purge initial value (EGR valve opening immediately before reduction, purge valve opening) is adjusted according to the reduction amounts ΔEGR, ΔPRG from the initial values. The ignition timing retard amount is set (see FIG. 14), and the ignition timing is retarded. As a result, the torque change due to the EGR / purge reduction control can be suppressed, and the drivability can be improved.

In the above embodiment (2), the ignition timing is corrected to suppress the torque change during the EGR / purge reduction control, but the fuel injection amount is changed to ΔEGR or ΔPRG during the EGR / purge reduction control. By correcting accordingly,
The torque change due to the EGR / purge reduction control may be suppressed.

When the present invention is applied to a system equipped with a variable valve timing mechanism (variable valve control means) for controlling the opening / closing timing or opening / closing time of at least one of the intake valve and the exhaust valve, the EGR / purge reduction amount is reduced. At the time of control, the opening / closing timing or opening / closing time (operating angle) of at least one of the intake valve and the exhaust valve is set to ΔEGR
Alternatively, the torque change due to the EGR / purge reduction control may be suppressed by making a correction according to ΔPRG or ΔPRG.

Further, the above-mentioned ignition timing correction, fuel injection amount correction, intake / exhaust valve opening / closing timing,
Combining two or more of the opening and closing time corrections
The torque change due to the R / purge reduction control may be suppressed.

<Embodiment (3)> In the embodiment (1), the air system is switched after the elapse of a predetermined delay period ECEGR from the start of the EGR / purge reduction control. The air system may be switched when the purge amount becomes smaller than the predetermined amount.

Embodiment (3) of the present invention that embodies this
Then, the air system control routine shown in FIG. 15 is executed in place of the air system control routine of FIG. 7 executed in the embodiment (1). In this air system control routine, first, when it is determined in step 601 that there is a combustion system switching request,
In step 602, the current EGR valve opening degree EGR (EGR amount) and the purge valve opening degree P are determined in order to determine whether it is the proper timing to start switching the air system.
It is determined whether RG (purge amount) is smaller than predetermined values E and P, respectively. Here, the predetermined values E and P are set to such values as the EGR amount and the purge amount at which the combustion state starts to stabilize. In the case where only one of the EGR valve 41 and the purge valve 46 is subjected to the reduction control, only the one performing the reduction control may be determined.

In step 602, EGR <E, PR
If at least one of G <P is determined to be “No”, it is determined that it is not the proper timing to start the switching of the air system, the process proceeds to step 604, and the count value of the air system switching counter CAIR is set. The routine is reset to 0 and this routine ends.

On the other hand, in step 602, EGR <
When both E and PRG <P are determined to be “Yes”, it is determined that the EGR amount and the purge amount at which the combustion starts to become stable are reduced, and the routine proceeds to step 603, where the air system ( The slot valve 15 and the swirl control valve 24) are switched to the opening degree according to the combustion system of the switching destination and the engine operating state.

On the other hand, if it is determined in step 601 that there is no combustion system switching request, the process proceeds to step 605, and the count value of the air system switching counter CAIR is set to 0.
Then, in the next step 606, the air system during normal control is controlled according to the current combustion system and engine operating state.

As in the embodiment (3) described above, E
If the air system is switched when the EGR amount and the purge amount become smaller than the predetermined amounts by the GR / purge reduction control, the combustion system is switched after the combustion stability is improved as in the case of the above embodiment (1). Therefore, it is possible to prevent the occurrence of misfire and torque shock when switching the combustion system.

<Embodiment (4)> By the way, when the EGR amount and the purge amount are already small and the combustion seems to be stable to some extent before the EGR / purge reduction control is executed, the EGR / purge reduction control is performed. Even if the switching of the air system is started at the same time as the start, no misfire or a large torque shock occurs when switching the combustion method.

Focusing on this point, in the embodiment (4) of the present invention, the EG of FIG. 6 executed in the embodiment (1) is executed.
Instead of the R amount / purge amount control routine, E shown in FIG.
The GR amount / purge amount control routine is executed.

In this EGR amount / purge amount control routine, in step 701, EGR / purge amount reduction control is in progress (E
When it is determined that the GR / purge reduction amount flag XDEC = ON), this routine is terminated without performing the subsequent processing, but the EGR / purge reduction amount flag is not in progress (EGR / purge reduction amount flag XDEC = OFF). If it is determined that the combustion system switching request is present, the process proceeds to step 702. If it is determined that there is a combustion method switching request, the routine proceeds to step 703, where the current EGR valve opening EGR (EGR amount) and purge valve opening PRG (purge amount) are smaller than predetermined values α and β, respectively. Determine whether or not. Here, the predetermined values α and β are set to values such that the EGR amount and the purge amount are small and the combustion is stable to some extent. In the case where only one of the EGR valve 41 and the purge valve 46 is subjected to the reduction control, only the one performing the reduction control may be determined.

At step 703, EGR <α, PR
When both of G <β are determined to be “Yes”, it is determined that the EGR amount and the purge amount are already small and the combustion is stable to some extent before the reduction control is performed, and the process proceeds to step 704 to perform the EGR / purge. The count value of the reduction counter CEGR is set to a predetermined value EC which is the start timing of switching the air system.
Set to EGR. As a result, the delay period from the start of the EGR / purge reduction amount to the start of switching the air system is set to 0, and the routine proceeds to step 706.

On the other hand, in step 703, EGR <α, P
When at least one of RG <β is determined to be “No” (when at least one of the EGR amount and the purge amount is large), the routine proceeds to step 705, where the count value of the EGR / purge reduction counter CEGR is reset to 0. After that, the process proceeds to step 706, and like step 203 of FIG.
The EGR valve opening degree EGR and the purge valve opening degree PRG are set to fixed values KEGR and KPRG, respectively, to start reduction control, and the EGR / purge reduction amount flag XDEC is set to ON (step 707).

Incidentally, the processing when it is judged in the above step 702 that there is no request for switching the combustion method (step 708-
710) is the same as steps 206 to 208 in FIG.

In the embodiment (4) described above, the EGR
If the EGR amount and the purge amount are already small and combustion is stable to some extent before the start of the purge reduction, the delay period from the start of the EGR / purge reduction control to the start of the air system switching is set to 0. , EGR / purge reduction is started, and at the same time, switching of the air system is started. As a result, when combustion is already stable to some extent before the start of EGR / purge reduction, it is possible to prevent the start timing of switching the air system from being unnecessarily delayed, and the combustion system switching time can be shortened.

In the above embodiment (4), the delay period is set to 0 when the EGR amount and the purge amount are already small before the start of the EGR / purge reduction amount, but the delay period may be set to be short. Further, when the EGR valve opening degree EGR and / or the purge valve opening degree PRG are smaller than the predetermined values α and β, the combustion method may be switched without executing the EGR / purge reduction control.

<Embodiment (5)> When EGR / purge reduction control is performed, the time required for combustion to start varies depending on the EGR amount and purge amount before the start of the reduction control.
Therefore, in the embodiment (5) of the present invention, the EGR amount / purge amount control routine shown in FIG. 17 is executed instead of the EGR amount / purge amount control routine of FIG. 6 executed in the embodiment (1). Then, a predetermined value ECEGR is set according to the EGR amount and the purge amount before the reduction control is started, and the delay period from the start of the EGR and purge reduction control to the start of the switching of the air system is set to the EGR amount and the purge before the reduction control is started. Vary according to the amount.

The EGR amount / purge amount control routine of FIG. 17 differs from that of FIG. 6 in that the processing of two steps 203a and 203b is added between step 202 and step 203. In this routine,
If it is determined in step 202 that there is a combustion mode switching request, the process proceeds to step 203a, where the EGR valve opening degree EGR (EGR amount) and the purge valve opening degree PRG (purge amount).
Is read, and at the next step 203b, the EGR valve opening E
The map using the GR and the purge valve opening PRG as parameters is searched to find the current EGR valve opening EGR and the purge valve opening P.
A predetermined value ECEGR corresponding to RG is obtained. The other processing is the same as in FIG. 6 of the above-described embodiment (1).

FIG. 18 shows an example of a map of a predetermined value ECEGR using the EGR valve opening EGR (purge valve opening PRG) as a parameter. The smaller the EGR amount (purge amount) before starting the reduction control, the shorter the time required until the combustion starts to stabilize. Therefore, the map characteristic of the predetermined value ECEGR in FIG. 18 is the EGR valve opening degree EGR (purge valve opening degree). In the region where PRG) is in the range of α1 to α2, the predetermined value ECEGR becomes smaller as the EGR valve opening EGR (purge valve opening PRG) becomes smaller, and in the region where the EGR valve opening EGR (purge valve opening PRG) becomes α1 or less. , EGR amount (purge amount) is small,
Since the combustion is stable, the predetermined value ECEGR is fixed to the minimum value (for example, 0). Also, the EGR valve opening degree EGR
When the (purge valve opening PRG) is larger than α2, E
Since the GR amount (purge amount) is large, the predetermined value ECEGR is fixed to the maximum value ECEGRmax.

In the case where both the EGR valve 41 and the purge valve 46 are controlled to be reduced as in the present embodiment (5), E
The final predetermined value ECEGR may be calculated from the predetermined value ECEGR obtained from the GR valve opening degree EGR and the predetermined value ECEGR obtained from the purge valve opening degree PRG, but the EGR valve opening degree EGR and the purge valve opening degree PRG may be calculated. In consideration of both of these, the predetermined value ECEGR may be comprehensively determined from the two-dimensional map or the like.

An execution example of the combustion method switching control of the embodiment (5) described above will be described with reference to the time chart of FIG. As shown in FIG.
When GR (purge valve opening PRG) is larger than α2,
When the count value of the EGR / purge reduction counter CEGR exceeds ECEGRmax after the start of EGR / purge reduction, the air system (throttle opening, swirl control valve opening) is switched.

Further, as shown in,
When the R valve opening EGR (purge valve opening PRG) is in the range of α1 to α2, EGR
When the count value of the purge reduction counter CEGR exceeds the predetermined value ECEGR set according to the EGR valve opening degree EGR (purge valve opening degree PRG), the air system is switched.

Further, as shown in,
When the R valve opening EGR (purge valve opening PRG) is smaller than α1, the predetermined value ECEGR is fixed to the minimum value (0), so that the air system is immediately switched when the combustion system switching request is generated. At this time, the air system may be switched without executing the EGR / purge reduction control, or the air system may be switched at the same time when the EGR / purge reduction control is started.

As described above, if the predetermined value ECEGR is set in accordance with the EGR amount and the purge amount before the reduction control is started, the time required for the combustion to be stabilized changes depending on the EGR amount and the purge amount before the reduction control is started. Accordingly, the timing of starting the switching of the air system can be optimized, and the combustion method can be switched in the minimum necessary time.

<Embodiment (6)> When the driver requests sudden acceleration or deceleration, some torque shock due to combustion mode switching is allowed, and responsiveness to the driver's request must be emphasized. There is. Therefore, in the embodiment (6) of the present invention, the EG of FIG. 6 executed in the embodiment (1) is executed.
Instead of the R amount / purge amount control routine, E shown in FIG.
By executing the GR amount / purge amount control routine, the combustion mode is switched without executing the EGR / purge reduction control at the time of sudden acceleration or sudden deceleration.

In the EGR amount / purge amount control routine of FIG. 20, first, at step 801, the change amount ΔAP of the accelerator opening is calculated from the change amount of the output signal of the accelerator sensor 42, and at step 802, the output of the throttle sensor 17 is output. The throttle opening change amount ΔTA is calculated from the signal change amount, and in step 803, the required fuel injection amount change amount Δq calculated by the ECU 16 according to the engine operating state.
To calculate.

Then, in the next step 804, EGR
During purge reduction control (EGR / Purge reduction flag XDE
When it is determined that C = ON, this routine is terminated without performing the subsequent processing, but the EGR / purge reduction amount control is not in progress (EGR / purge reduction amount flag XDEC =
When it is determined to be OFF), the process proceeds to step 805, and it is determined whether there is a combustion method switching request. If it is determined that there is a combustion mode switching request, step 80
In order to determine whether or not the vehicle is in a rapid acceleration state,
It is determined whether any one of ΔAP> predetermined value L1, ΔTA> predetermined value M1, and Δq> predetermined value N1 holds. Here, the respective predetermined values K1, M1, N1 are set to the accelerator opening change amount, the throttle opening change amount, and the required fuel injection amount change amount which are determined to be in the rapid acceleration state. If this step 8
If any one of the conditions is satisfied in 06, it is determined that the vehicle is in the rapid acceleration state, and the process proceeds to step 808.

If none of ΔAP> predetermined value L1, ΔTA> predetermined value M1 and Δq> predetermined value N1 is satisfied in step 806, the process proceeds to step 807 to determine whether or not the vehicle is in a rapid deceleration state. For this reason, ΔAP <predetermined value L2
, ΔTA <predetermined value M2 and Δq <predetermined value N2 are satisfied. Here, each predetermined value K2,
M2 and N2 are set to the accelerator opening change amount, the throttle opening change amount, and the required fuel injection amount change amount, which are determined to be in the rapid deceleration state. If at step 807, either 1
If any of the conditions is satisfied, it is determined that the vehicle is in a rapid deceleration state, and the process proceeds to step 808.

In this step 808, the count value of the EGR / purge reduction counter CEGR is set to a predetermined value ECEGR which is the switching start timing of the air system.
As a result, the delay time from the start of EGR / purge reduction to the start of air system switching is set to zero. In the next step 809, the EGR / purge reduction amount flag XDEC is set to O.
After setting to N, at step 810, EGR valve opening E
The GR and the purge valve opening PRG are set by a map or the like according to the engine speed Ne, the load, the combustion method, etc.
・ EGR valve 41 and purge valve 46 at the same time when the purge amount reduction is started
Is switched according to the combustion system at the switching destination and the engine operating state.

On the other hand, if it is determined to be "No" in steps 806 and 807, it is determined that neither rapid acceleration nor rapid deceleration occurs, and the process proceeds to step 811.
Set the count value of the EGR / purge reduction counter CEGR to 0.
Reset to. Thereafter, at step 812, the EGR valve opening degree EGR (EGR amount) and the purge valve opening degree PRG (purge amount) are set to fixed values KEGR and KPRG, and EGR.
The purge reduction control is started, and in the next step 813, EG
R-Purge reduction flag XDEC is set to ON.
In this case, the processes of steps 806 and 807 described above serve as the acceleration / deceleration determining means in the claims.

Incidentally, in the above step 805, the processing when it is judged that there is no combustion system switching request (step 814, step 814)
815, 810) are steps 206 to 20 in FIG.
Same as 8.

An execution example of the combustion system switching control of the embodiment (6) described above will be described with reference to the time chart of FIG. When the accelerator opening is suddenly increased to a rapid acceleration state, a combustion switching request is generated. As a result, EGR
Immediately switch the EGR valve opening and the purge valve opening according to the combustion method of the switching destination without executing the purge reduction control.
At the same time, switching of the air system (throttle opening) is started, and thereafter, the fuel system / ignition system is switched for a while.

By doing so, as compared with the case where the combustion system is switched after a predetermined delay period from the start of the EGR / purge reduction control as shown in the embodiment (1) (indicated by the broken line in the figure). It is possible to switch the combustion system with good responsiveness, and it is possible to prevent the driver from feeling a rattling during acceleration.

Further, in the above embodiment (6), the acceleration / deceleration is determined based on changes in the accelerator opening, the throttle opening, and the required fuel injection amount. Therefore, the accelerator sensor installed in a normal vehicle is used. 42, the acceleration / deceleration can be determined from the output of the throttle sensor 17 and the calculated value of the ECU 16. Therefore, it is not necessary to newly provide an acceleration sensor for determining the acceleration / deceleration, and it is possible to satisfy the demands for the reduction in the number of parts and the cost reduction.

In addition, the acceleration / deceleration can be determined from the change in the vehicle speed. Therefore, the acceleration / deceleration may be determined based on a change in at least one of the accelerator opening, the throttle opening, the required fuel injection amount, and the vehicle speed.

In the above embodiment (6), the EGR / purge reduction control is not executed at the time of sudden acceleration and deceleration, and the combustion system is switched with good responsiveness.
Even during sudden deceleration, EGR / purge reduction control is performed to
The switching of the air system (throttle opening degree, etc.) may be started at the same time when the GR / purge reduction is started.

In this case, using the map shown in FIG.
Predetermined value EC according to acceleration / deceleration (ΔAP, ΔTA, Δq)
By setting EGR and shortening the delay time from the start of EGR / purge reduction control to the start of switching the air system during rapid acceleration and rapid deceleration, the combustion method may be switched with good responsiveness. . The characteristic of the map of FIG. 22 is the region (ΔAP> L1, ΔT) which is determined to be in the rapid acceleration state.
A> M1, Δq> N1) and the regions (ΔAP <L2, ΔTA <M2, Δq <N2) that are determined to be in a sudden deceleration state, the predetermined value ECEGR is set to be smaller as the amount of change is larger. Has been done. As a result, when the driver requests a sudden acceleration and a sudden deceleration, emphasis is placed on responsiveness,
The combustion system can be quickly switched to eliminate the feeling of rattling during acceleration and the feeling of idling during deceleration.

<< Embodiment (7) >> For example, in a driving range in which the driver does not feel much torque shock at the time of switching the combustion system, such as during high load operation or idle operation,
It is preferable to quickly switch the combustion system in response to the combustion system switching request.

Therefore, in the embodiment (7) of the present invention, the EGR amount / purge amount control routine shown in FIG. 23 is replaced with the EGR amount / purge amount control routine of FIG. 20 executed in the embodiment (6). Run.

In the EGR amount / purge amount control routine of FIG. 23, first, the accelerator opening AP is read in step 801a, and the required fuel injection amount q is read in step 802a. Then, in the next steps 804 and 805, the purge amount reduction control is not in progress (the purge amount reduction control flag XDEC =
(OFF), and when it is determined that there is a combustion method switching request, the process proceeds to step 806a, and it is determined whether or not the operating region is such that torque shock during combustion method switching is not felt so much during high load operation. AP>
It is determined whether or not one of the predetermined values Q1 and q> predetermined value P1 is satisfied. Here, the respective predetermined values Q1 and P1 are set to the accelerator opening and the required fuel injection amount which are determined to be in the high load operation state. If any one of the conditions is satisfied in step 806a, it is determined that the operating region is in the high load operating state and the torque shock at the time of switching the combustion system is not felt so much. 808
Proceed to.

If AP> predetermined value Q1 and q> predetermined value P1 are not satisfied in step 806a, the process proceeds to step 807a, in which torque shock is not felt when the combustion system is switched as in low load operation. AP <predetermined value Q2,
It is determined whether q <predetermined value P2 holds. here,
The predetermined values Q2 and P2 are set to the accelerator opening and the required fuel injection amount which are determined to be in the low load operation state. If any one of the conditions is satisfied in step 807a, it is determined that the operating condition is in the low load operating condition and the torque shock at the time of switching the combustion system is not felt so much, Go to step 808.

If AP <predetermined value Q2 and q <predetermined value P2 are not satisfied at step 807a, it is determined that neither high load operation nor low load operation is performed, and the routine proceeds to step 811. In this case, the processes of step 806a and step 807a serve as the operating area determination means in the claims. Processing other than the above is
This is the same as the processing of FIG. 20 described in the embodiment (6).

As described above, in an operating region where the driver does not feel the torque shock at the time of switching the combustion system, such as during high load operation or low load operation, the EGR / purge reduction control is not executed and the combustion is performed. By promptly switching the combustion system in response to the system switching request, the combustion system switching time can be shortened.

Even during the high load operation or the low load operation, the EGR / purge reduction control is executed so that the switching of the air system (throttle opening etc.) is started at the same time when the EGR / purge reduction is started. Is also good.

In this case, using the map shown in FIG.
By setting a predetermined value ECEGR according to the operating region (AP, q) and shortening the delay time from the start of EGR / purge reduction control to the start of air system switching during high load operation or low load operation Alternatively, the combustion method may be switched with good responsiveness. The characteristic of the map of FIG. 24 is that, in the high load operation region (AP> Q1, q> P1) and the low load operation region (AP <Q2, q <P2), the higher the load becomes, the lower the predetermined value ECEGR becomes. Is set to be small. As a result, the combustion system switching time can be shortened as the operating range in which the torque shock during switching the combustion system is felt to be small.

In each of the above embodiments (1) to (7),
The delay period from the start of the EGR / purge reduction control to the start of the air system switching is determined by the elapsed time (the count value of the EGR / purge reduction counter). The number of cycles (the number of rotations of the crank shaft) and the crank angle may be counted by a counter and the determination may be made from the count value.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an entire engine control system system according to an embodiment (1) of the present invention.

FIG. 2A is a diagram showing a stable combustion region of stratified combustion and homogeneous combustion before EGR / purge reduction control, and FIG.
The figure which shows the stable combustion region of stratified charge combustion and homogeneous combustion during purge reduction control.

FIG. 3 is a flowchart showing a processing flow of a combustion method switching control main routine.

FIG. 4 is a flowchart showing a processing flow of a combustion system switching request determination routine.

FIG. 5 is a diagram for explaining a combustion method switching determination according to a load.

FIG. 6 is a flowchart showing a processing flow of an EGR amount / purge amount control routine in the embodiment (1).

FIG. 7 is a flowchart showing a flow of processing of an air system control routine in the embodiment (1).

FIG. 8 is a flowchart showing the flow of processing of a fuel system / ignition system control routine.

FIG. 9 is a time chart showing an example when the combustion method switching control of the embodiment (1) is executed.

FIG. 10 is a time chart showing an example of a case where conventional combustion method switching control is executed.

FIG. 11 is a flowchart showing the flow of torque correction routine processing in the embodiment (2) of the present invention.

FIG. 12 is a diagram showing a relationship between a reduction amount ΔEGR (ΔPRG) and an ignition timing retard amount.

FIG. 13 is a time chart showing an example when the combustion method switching control of the embodiment (2) is executed.

FIG. 14 is a diagram for explaining the behavior of the ignition timing retard amount.

FIG. 15 is a flowchart showing a processing flow of an air system control routine in the embodiment (3) of the present invention.

FIG. 16 is a graph showing the EGR amount in the embodiment (4) of the present invention.
Flowchart showing the flow of processing of the purge amount control routine

FIG. 17 is an EGR amount in the embodiment (5) of the present invention.
Flowchart showing the flow of processing of the purge amount control routine

FIG. 18: EGR valve opening degree EGR (purge valve opening degree PGR)
And a diagram showing the relationship between the predetermined value ECEGR

FIG. 19 is a time chart showing an example when the combustion method switching control of the embodiment (5) is executed.

FIG. 20 is a graph showing the EGR amount in the embodiment (6) of the present invention.
Flowchart showing the flow of processing of the purge amount control routine

FIG. 21 is a time chart showing an example when the combustion method switching control of the embodiment (6) is executed.

FIG. 22 is an accelerator opening change amount ΔAP (throttle opening change amount ΔTA, required fuel injection amount change amount Δq) and a predetermined value E.
Diagram showing the relationship with CEGR

FIG. 23 is an EGR amount in the embodiment (7) of the present invention.
Flowchart showing the flow of processing of the purge amount control routine

FIG. 24 is a diagram showing a relationship between an accelerator opening AP (requested fuel injection amount q) and a predetermined value ECEGR.

[Explanation of symbols]

11 ... Cylinder injection type engine (cylinder injection type internal combustion engine), 1
2 ... Intake pipe, 14 ... Step motor (throttle control means), 15 ... Throttle valve, 16 ... ECU (Combustion method switching control means, torque correction means, acceleration / deceleration determination means, operating area determination means), 17 ... Throttle sensor, 18 ... Accelerator pedal, 19 ... Surge tank, 24 ... Swirl control valve (swirl flow control means), 26 ... Step motor,
27 ... Swirl control valve sensor, 28 ... Fuel injection valve, 37
... Exhaust pipe, 39 ... Lean NOx catalyst, 40 ... EGR pipe, 41 ... EGR valve (exhaust gas recirculation means), 42 ... Accelerator sensor, 43 ... Fuel tank, 44 ... Canister, 45 ...
Purge pipe, 46 ... Purge valve (fuel evaporative gas purge means).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F02D 41/02 325 F02D 41/02 325E 325J 43/00 301 43/00 301B 301H 301J 301K 301N 301U F02M 25/07 550 F02M 25 / 07 550R 570 570A 25/08 301 25/08 301U F02P 5/15 F02P 5/15 FG (56) Reference JP-A-11-62731 (JP, A) JP-A-10-68344 (JP, A) Kaihei 7-332071 (JP, A) JP-A-11-36998 (JP, A) JP-A-6-159119 (JP, A) JP-A-9-170467 (JP, A) (58) Fields investigated (58) Int.Cl. ⁷ , DB name) F02D 41/00-45/00 F02P 5/15 F02M 25/07 F02M 25/08

Claims (10)

(57) [Claims] 1. A cylinder comprising at least one of an exhaust gas recirculation means for recirculating a part of exhaust gas to an intake system and a fuel evaporative gas purge means for purging a fuel evaporative gas generated in a fuel tank to an intake system, and a fuel injection valve to a cylinder. Directly inject fuel into
In an internal combustion engine controller that controls the fuel system, ignition system, and air system so that the combustion system is switched between stratified combustion and homogeneous combustion according to the combustion system switching request, the exhaust gas recirculation is performed when the combustion system switching request occurs. Control for reducing or zeroing the exhaust gas recirculation amount by the means and / or the purge amount by the fuel evaporative gas purging means
After a predetermined delay period
In addition, the control amount of the air system is changed according to the combustion method of the switching destination.
The control to switch is started, and then the fuel system and the point
Switching the control amount of the fire system according to the combustion method of the switching destination
Therefore, the internal combustion engine control device is provided with a combustion system switching control means for switching the combustion system. 2. The combustion system switching control means switches the control amount of the fuel system and the ignition system according to the combustion system of the switching destination, or at the same time, or after the switching, the exhaust gas recirculation means and / or the exhaust gas recirculation means. 2. The internal combustion engine control device according to claim 1 , wherein the control of the fuel evaporative emission gas purge means is switched from the reduction control to a normal control according to the combustion system after switching. 3. A variable valve control means for controlling the opening / closing timing or opening / closing time of at least one of an intake valve and an exhaust valve, and the ignition system, the fuel system, and the variable valve control means of the ignition system, the fuel system, and the variable valve control means during the period of the reduction control. claim 1 also characterized in that at least one control variable and a torque correcting means for correcting the direction to suppress the torque variation due to the decrease control
Is an internal combustion engine controller according to item 2 . 4. The internal combustion engine control device according to claim 3 , wherein the torque correction means sets the torque correction amount according to the amount of reduction by the reduction control. Wherein said combustion mode switching control means is any one of claims 1 to 4, characterized in that set on the basis of the delay period to at least one of the exhaust gas recirculation amount and the purge amount before the reduction control is started The internal combustion engine control device according to. 6. The combustion system switching control means sets the delay period to zero or short when at least one of the exhaust gas recirculation amount and the purge amount before starting the reduction control is smaller than a predetermined value, or the reduction control. not performed, an internal combustion engine control apparatus according to any one of claims 1 to 5, characterized in that switched in accordance with the combustion mode switching destination control amount of the air system. 7. An acceleration / deceleration determining means for determining an acceleration / deceleration of a vehicle, wherein the combustion method switching control means sets the delay period to zero when the acceleration / deceleration determined by the acceleration / deceleration determining means is larger than a predetermined value. or short set, or not perform the decrease control, claim 1, characterized in that switched in accordance with the control amount of the air based on the combustion system of the switching destination
7. The internal combustion engine control device according to any one of 1 to 6 . Wherein said acceleration determining means according to claim 7, wherein determining the accelerator opening, the throttle opening, the amount required fuel injection, the acceleration based on at least one change in the vehicle speed Internal combustion engine control device. 9. An operating range determining means for determining an operating range of the internal combustion engine, wherein the combustion mode switching control means is configured to delay the delay when the operating range determined by the operating range determining means is within a predetermined operating range. The control amount of the air system is switched according to the combustion system of the switching destination without setting the period to zero or short or performing the reduction control.
The internal combustion engine controller according to any one of 1 to 8 . 10. The predetermined operation region is set to at least one of a region where an accelerator opening or a required fuel injection amount is a predetermined value or more and a region where an accelerator opening or a required fuel injection amount is a predetermined value or less. The internal combustion engine control device according to claim 9 , wherein