JP4788682B2 - Internal combustion engine control device - Google Patents

Description

  The present invention relates to an internal combustion engine controller that performs ignition timing significant retard control for warming up an exhaust gas purification catalyst for an internal combustion engine.

In order to warm up the exhaust gas purification catalyst provided in the internal combustion engine, the ignition timing is greatly retarded (see, for example, Patent Documents 1 and 2). When such a large ignition delay processing is executed, the operation of the internal combustion engine may become unstable due to problems such as combustibility and the rotational speed may decrease. Ignition timing advance is executed to cope with such instability of internal combustion engine operation and to quickly recover the rotational speed.
JP 2007-32377 A (6th page, FIG. 2) JP 2007-32379 A (page 4, FIG. 1)

  However, the cause of the unstable operation of the internal combustion engine that causes such a decrease in the rotational speed is not uniform. For this reason, in any case, the ignition timing advance processing and other methods may not be able to adequately cope with the cause of internal combustion engine instability by using only one method. Is not limited.

  An object of the present invention is to appropriately return from an unstable internal combustion engine operation state to a stable internal combustion engine operation at the time of ignition timing significant retard control for warming up an exhaust purification catalyst of the internal combustion engine.

In the following, means for achieving the above object and its effects are described.
The internal combustion engine control apparatus according to claim 1 is an internal combustion engine control apparatus at the time of ignition timing significant retardation control for warming up an exhaust gas purification catalyst of the internal combustion engine, wherein the rotational speed and load of the internal combustion engine are parameters. In the two-dimensional space represented as, the intake air amount-induced instability region indicating the instability due to the intake air amount shortage of the internal combustion engine and the operation instability due to the deterioration of the combustion state of the internal combustion engine are shown an internal combustion engine operating instability region setting means for setting the combustion state due unstable area as a destabilizing regions oPERATION destabilizing results of the internal combustion engine, an internal combustion engine operating condition detecting for detecting an operating state of the internal combustion engine And the operation state of the internal combustion engine detected by the internal combustion engine operation state detection means is the intake air amount-induced instability region set by the internal combustion engine operation instability region setting unit and the combustion Condition From the area other than the unstable region, wherein when entering either of destabilization region of the intake air amount due destabilization region and the combustion state due unstable region, corresponding to the relevant destabilization region And a region corresponding internal combustion engine stabilization processing means for executing processing to exit from the instability region in the internal combustion engine stabilization processing , wherein the region corresponding internal combustion engine stabilization processing means is configured such that the operating state of the internal combustion engine is the intake. When the air amount-induced instability region is entered, as the internal combustion engine stabilization processing, by increasing the intake air amount of the internal combustion engine, a process for exiting the intake air amount-based instability region is executed. When the operating state of the engine enters the combustion state-induced instability region, as the internal combustion engine stabilization process, the ignition timing of the internal combustion engine is advanced so as to exit the combustion state-induced instability region. Characterized by a run.

In this way, an intake air amount-induced instability region and a combustion state-induced instability region are set in a two-dimensional space represented by the rotational speed and load of the internal combustion engine as parameters, and the operating state of the internal combustion engine is determined by these. When entering the instability region, a process for exiting the instability region is executed by the internal combustion engine stabilization processing corresponding to the corresponding instability region.
Further, when the operating state of the internal combustion engine enters the intake air amount-induced instability region, a sufficient intake air amount is supplied to the internal combustion engine by executing an increase of the intake air amount as the internal combustion engine stabilization process. As a result, the engine output increases. On the other hand, when the operating state of the internal combustion engine enters the instability region caused by the combustion state, the ignition timing of the internal combustion engine is advanced as the internal combustion engine stabilization process, so that the internal combustion engine has good combustibility and is stable. The output becomes higher and the rotational speed increases.

Since the internal combustion engine stabilization process corresponding to each instability region is executed in this way, appropriate processing to escape from the instability is performed, and the stable internal combustion engine operation state is restored at an early stage. Can do.
Here, as in the conventional case, if uniform processing is performed for any instability region, there is a possibility that a delay may occur in returning to stable internal combustion engine operation. Specifically, if control related to flammability is executed in order to get out of the instability region due to the intake air amount, stabilization is attempted instead of appropriate processing because it tries to achieve stabilization due to different factors. There may be a delay in returning to the internal combustion engine operation.
The reverse is also the same, and when control related to the intake air amount is executed in order to exit from the unstable state due to the combustion state, stabilization is attempted by different factors. There may be a delay in returning to stable internal combustion engine operation.

  Therefore, by performing the processing according to the present invention, it is possible to appropriately return from the unstable operation state of the internal combustion engine to the stable internal combustion engine operation at the time of ignition timing significant retard control for warming up the exhaust purification catalyst of the internal combustion engine. Become.

  According to a second aspect of the present invention, in the internal combustion engine control device according to the first aspect, when the region corresponding internal combustion engine stabilization processing means executes the processing to exit from the corresponding instability region, the operating state of the internal combustion engine is first determined. The entered destabilized region is set as the corresponding destabilized region, and the process of exiting from the corresponding destabilized region is executed in the internal combustion engine stabilizing process corresponding to the region.

  When the operating state of the internal combustion engine becomes unstable, this operating state tends to first enter the instability region corresponding to the corresponding driving instability factor. Therefore, when the destabilization areas overlap, the internal combustion engine stabilization process is performed for the destabilization areas where the operating state of the internal combustion engine first enters, so that the appropriate destabilization areas can be exited. Processing can be executed.

In an internal combustion engine control apparatus according to claim 3, wherein in claim 1 or 2, an internal combustion engine includes a cylinder fuel supply system for fuel injection into the combustion chamber, operating conditions the combustion state due unstable region of the internal combustion engine If the in-cylinder fuel supply system is performing fuel injection in the compression stroke when the engine enters, the region-corresponding internal combustion engine stabilization processing means performs the ignition timing advancement as the internal combustion engine stabilization processing. Along with the angle, the fuel injection timing of the compression stroke is advanced corresponding to the advance angle.

  If the compression stroke fuel injection timing control corresponding to the ignition advance is further performed in addition to the ignition advance, the state of the air-fuel mixture at the time of ignition becomes good. For this reason, in the internal combustion engine, the combustibility becomes good, the output becomes stable, and the rotational speed increases. This makes it possible to return to an appropriately stable internal combustion engine operation.

In an internal combustion engine control apparatus according to claim 4, in any one of claims 1 to 3, the internal combustion engine is an internal combustion engine for a vehicle, with use of the intake negative pressure of the internal combustion engine to brake assist, the combustion state due not The stabilization region is characterized by being set to overlap with the region of the intake pipe negative pressure that is insufficient for brake assist.

  The internal combustion engine stabilization process performed in response to the instability of operation caused by the deterioration of the combustion state is also common with the process of ensuring the brake assist intake pipe negative pressure. Therefore, as described above, the combustion state-induced instability region is overlapped with the region of the intake pipe negative pressure that is insufficient with respect to the brake assist, so that the region-corresponding internal combustion engine stabilization processing means not only stabilizes the operation of the internal combustion engine but also increases the brake assist force. Insufficiency can also be prevented.

The internal combustion engine control apparatus according to claim 5 , wherein the intake air amount-induced instability region is set by providing an upper limit depending on the rotational speed of the internal combustion engine in any one of claims 1 to 4. And

Thus, the intake air amount-induced instability region can be easily determined whether or not the intake air amount is insufficient by setting the upper limit of the region based on the rotational speed of the internal combustion engine.
The internal combustion engine control apparatus according to claim 6 , wherein the internal combustion engine has weak stratified combustion as one of combustion modes in any one of claims 1 to 5 , and the region corresponding internal combustion engine stabilization processing means includes weak stratified combustion Only during combustion execution, the operating state of the internal combustion engine detected by the internal combustion engine operating state detection means is other than all the destabilization areas set by the internal combustion engine operation instability area setting means. When entering any one of the destabilized regions from the region, a process of exiting from the corresponding destabilized region is executed in the internal combustion engine stabilizing process corresponding to the corresponding destabilized region.

  As described above, the stabilization processing by the region corresponding internal combustion engine stabilization processing means may be limited to the execution of weak stratified combustion. In particular, during the execution of weak stratified combustion, the internal combustion engine is in an operating state that easily enters the unstable region. Therefore, the load of the control process can be reduced by limiting to the execution of weak stratified combustion in this way.

[Embodiment 1]
FIG. 1 is a system configuration diagram of a vehicle internal combustion engine to which the above-described invention is applied and a control device therefor. Here, a gasoline engine (hereinafter referred to as “engine”) 2 is used as the internal combustion engine. The engine 2 is an in-cylinder injection gasoline engine, and the output thereof is output from the crankshaft of the engine 2 through a torque converter 4 and an automatic transmission (hereinafter referred to as “A / T”) 6 to an output shaft. It is output to the 6a side and finally transmitted to the wheel.

  Fuel injection control by the fuel injection valve 8 that directly injects fuel into the combustion chamber, opening control of the throttle valve 14 provided in the intake pipe 12 by the electric motor 10, and other engine control are executed by an EG (engine) -ECU 16. Is done. In addition, by providing a VSC (Vehicle Stability Control) -ECU 18, automatic control of the brakes of each wheel is also executed.

  The EG-ECU 16 includes an engine coolant temperature THW from the water temperature sensor 19, an accelerator opening ACCP from the accelerator opening sensor 20, a vehicle speed SPD from the vehicle speed sensor 21, a throttle opening TA from the throttle opening sensor 22, and an engine speed sensor 24 from the engine speed sensor 24. The rotational speed NE is detected. Further, the EG-ECU 16 detects the intake pressure PIM in the surge tank 28 from the intake pressure sensor 26, the atmospheric pressure PA from the atmospheric pressure sensor 30, the air-fuel ratio A / F based on the exhaust component from the air-fuel ratio sensor 31, and other data. ing. Instead of the sensors described above, sensors using various known detection principles may be selected as appropriate. For example, instead of the intake pressure sensor 26, an intake air amount sensor is provided in the intake pipe 12, and the intake air amount obtained thereby is divided by the engine speed NE obtained by the engine speed sensor 24. May be calculated. In addition to directly measuring the atmospheric pressure PA by the atmospheric pressure sensor 30, the atmospheric pressure PA may be calculated based on the detected values of the intake pressure sensor 26 and the intake air amount sensor.

  The VSC-ECU 18 detects operation data of the brake pedal 32 for braking control or the like. The brake pedal 32 is provided with a brake switch 34 and outputs a signal indicating the depression state of the brake pedal 32 to the VSC-ECU 18. A brake booster 36 is provided as a booster that increases the depression force of the brake pedal 32. The brake booster 36 has two pressure chambers 36b and 36c formed by being partitioned by a diaphragm 36a. Among these, a brake booster pressure sensor 38 is provided in the first pressure chamber 36b to detect the brake booster pressure PB in the first pressure chamber 36b. An intake negative pressure is supplied to the first pressure chamber 36b for brake assist from the surge tank 28 via the check valve 36d.

  The brake booster 36 functions as follows. That is, when the brake pedal 32 is not depressed, the negative pressure control valve 36e provided in the brake booster 36 introduces the negative pressure in the first pressure chamber 36b into the second pressure chamber 36c. For this reason, since the first pressure chamber 36b and the second pressure chamber 36c are in the same negative pressure state, the diaphragm 36a is pushed back toward the brake pedal 32 by the spring 36f. For this reason, the push rod 36g interlocked with the diaphragm 36a does not push the piston in the master cylinder 36h.

  On the other hand, when the brake pedal 32 is depressed, the negative pressure control valve 36e shuts between the first pressure chamber 36b and the second pressure chamber 36c in conjunction with the input side rod 36i provided on the brake pedal 32, Air is introduced into the second pressure chamber 36c. As a result, a differential pressure is generated between the first pressure chamber 36b in the intake negative pressure state and the second pressure chamber 36c having the atmospheric pressure. For this reason, the stepping force against the brake pedal 32 is doubled, and the diaphragm 36a pushes the push rod 36g toward the master cylinder 36h against the urging force of the spring 36f. As a result, the piston in the master cylinder 36h is pushed and braking is performed.

  When the brake pedal 32 is returned, the negative pressure control valve 36e shuts off the communication between the second pressure chamber 36c and the outside air in conjunction with the input side rod 36i provided on the brake pedal 32, and the first pressure chamber 36b. And the second pressure chamber 36c are in communication. As a result, intake negative pressure is introduced from the first pressure chamber 36b into the second pressure chamber 36c. Therefore, the first pressure chamber 36b and the second pressure chamber 36c have the same pressure. Therefore, the diaphragm 36a moves to the brake pedal 32 side by the urging force of the spring 36f, and returns to the original non-braking state. As described above, the brake booster 36 uses the negative pressure in the surge tank 28.

  A catalytic converter 42 is disposed in the exhaust pipe 40. Exhaust gas from the combustion chamber of the engine 2 is purified and discharged by the exhaust gas purifying catalyst disposed in the catalytic converter 42. The EG-ECU 16 estimates and calculates the catalyst bed temperature of the exhaust purification catalyst from the operating state of the engine 2, and when it is cold, the EG-ECU 16 significantly increases the warming up of the exhaust purification catalyst via the ignition system 44. Ignition retard is running.

  Each of the ECUs 16 and 18 described above is configured mainly with a microcomputer, and the CPU executes necessary arithmetic processing in accordance with a program written in an internal ROM, and various controls are performed based on the calculation results. Is running. These arithmetic processing results and data detected as described above are exchanged between the ECUs 16 and 18 as necessary. Thus, the ECUs 16 and 18 can execute control in conjunction with each other.

  The engine 2 is executed by switching the combustion mode between a plurality of modes (stratified combustion, weakly stratified combustion, and homogeneous combustion) having different air-fuel ratios or fuel injection methods. When the stratified combustion mode is selected, fuel is injected during the compression stroke. For this reason, the air-fuel mixture in the vicinity of the spark plug 44a in the combustion chamber is in a rich state that can be partially ignited at the time of ignition. In this stratified combustion, the average air-fuel ratio (A / F) of the air-fuel mixture is set to be leaner (A / F = 25-50) than the stoichiometric air-fuel ratio (A / F = 14.5). When the weak stratified combustion mode is selected, the fuel is injected in two parts of an intake stroke and a compression stroke, and the air-fuel ratio is set to be leaner (A / F = 20 to 30) than the stoichiometric air-fuel ratio. . In this weakly stratified combustion, since a part of the fuel is injected in the intake stroke, the difference in the air-fuel ratio in the combustion chamber at the time of ignition is smaller than in stratified combustion. When the homogeneous combustion mode is selected, fuel is injected in the intake stroke. In this homogeneous combustion, since all the fuel is injected in the intake stroke, the air-fuel ratio in the combustion chamber at the time of ignition becomes substantially uniform, and the air-fuel ratio is the stoichiometric air-fuel ratio, lean (A / F = 15 to 23) and rich (A / F = 11 to 13).

  Next, FIGS. 2 and 3 are flowcharts of the engine stabilization control executed by the EG-ECU 16 when the exhaust gas purification catalyst is warmed up. These processes are repeatedly interrupted at regular time intervals. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  The unstable state determination process in FIG. 2 will be described. When this processing is started, first, as shown in FIG. 4, the intake air amount lowering line La (one-dot chain line) and the combustion worsening line Lb (two-dot chain line) in a two-dimensional space of the engine load factor KL and the engine speed NE. Are set (S102). The engine load factor KL is a ratio (%) of the actual intake air amount to the reference maximum intake air amount per rotation of the engine 2, and is calculated from the intake pressure PIM (Pa) and the engine speed NE (rpm). . As the load of the engine 2, in addition to such a load factor, the intake pressure PIM itself or an intake air amount (g / s) detected by providing an intake air amount sensor may be used.

  Here, the intake air amount decrease line La represents the upper limit of the engine speed NE in the intake air amount-induced instability region. This intake air amount-induced instability region is a region that shows engine operation instability due to a shortage of the intake air amount of the engine 2 when the ignition timing for retarding the exhaust purification catalyst is greatly retarded. That is, in FIG. 4, the portion where the rotational speed is lower than the intake air amount reduction line La is set as the intake air amount-induced instability region.

  The combustion deterioration line Lb represents a boundary line in the combustion state-induced instability region, and represents an upper limit for the engine speed NE and a lower limit for the load factor KL in the combustion state-induced instability region. This combustion state-induced instability region is a region in which engine operation becomes unstable due to deterioration of the combustion state of the engine 2 when the ignition timing for retarding the exhaust gas purification catalyst is greatly retarded. That is, in FIG. 4, the lower right portion of the combustion deterioration line Lb is set as a combustion state-induced instability region.

It should be noted that a region other than both the intake air amount-induced instability region and the combustion state-induced instability region, that is, a region controlled in the normal state is shown as “stable region” in FIG.
In particular, the combustion deterioration line Lb is set so that the combustion state-induced instability region overlaps the region of the intake pipe negative pressure that is insufficient for the brake assist. The boundary line of the combustion state-induced instability region is a line substantially parallel to the boundary line of the intake pipe negative pressure shortage line for brake assist. Actually, the limit of the combustion deterioration exists on the side where the load factor KL is larger than the combustion deterioration line Lb or the side where the engine speed NE is smaller. In the present embodiment, the region where the brake assist intake pipe negative pressure is insufficient is set so as to overlap the combustion state-induced instability region. As a result, the combustibility is sufficient on the low load factor side and the large rotational speed side of the combustion deterioration line Lb, and the intake negative pressure level for the brake assist is also sufficient. As will be described later, the internal combustion engine stabilization process (FIG. 3: S134) performed in response to engine operation instability due to deterioration of the combustion state is also common with the process of ensuring the brake assist intake pipe negative pressure. Become.

  These two lines La and Lb change at the engine coolant temperature THW (° C.) and the atmospheric pressure PA (Pa). Accordingly, in step S102, the two lines La and Lb are calculated by correcting the respective basic lines from the map using the engine coolant temperature THW and the atmospheric pressure PA stored in the EG-ECU 16 as parameters. . When idling, the intake air amount reduction line La may be set at a value several hundred rpm lower than the target idling (actually cold idling) target rotational speed, for example, a value 200 rpm lower.

  When the two lines La and Lb are set in this way and the region distribution in the two-dimensional space of FIG. 4 is determined, the position of the current operating state of the engine 2 in the two-dimensional space is then calculated. (S104).

  Then, as a result of this position calculation, it is determined whether or not the vehicle is in the stable region during the previous control cycle and has exited from the intake air amount reduction line La during the current control cycle (S106). That is, as shown by the solid line in FIG. 4, when the engine has moved from the engine operating state position Xo to the position Xa1 or the position Xa2, it is determined that it has exited from the intake air amount reduction line La (yes in S106). In this case, the intake air amount-induced destabilization flag Fa is set to ON (S108), and the process is temporarily exited. The initial value of the intake air amount-induced destabilization flag Fa is set to OFF when the EG-ECU 16 is started.

  As shown by the solid line in FIG. 4, when the engine has moved from the engine operating state position Xo to the position Xb1 or the position Xb2, since it has exited from the combustion deterioration line Lb, it is not determined that it has exited from the intake air amount reduction line La (S106). No). Therefore, it is next determined whether or not the vehicle is in the stable region during the previous control cycle and exits from the combustion deterioration line Lb during the current control cycle (S110). Here, it is determined yes, the combustion state-induced instability flag Fb is set to ON (S112), and the process is temporarily exited. Note that the initial value of the combustion state-induced instability flag Fb is set to OFF when the EG-ECU 16 is started.

  When the vehicle passes through the intersection C between the intake air amount lowering line La and the combustion deterioration line Lb and leaves the stable region, it is determined whether the intake air amount destabilization or the combustion state destabilization is performed. Set in advance. For example, if the intersection point C is set to be instability due to combustion state, it is no in step S106, but it is determined to be yes in step S110, and ON is set in the combustion state instability flag Fb. (S112). If it is set that the passage of the intersection C is due to the intake air amount destabilization, it is determined yes in step S106, and the intake air amount destabilization flag Fa is set to ON (S108). .

  If the previous time is in the unstable region due to intake air amount or in the unstable region due to combustion state and this time is in the stable region (no in S106, no in S110, yes in S114), the intake air amount Both the cause destabilization flag Fa and the combustion state cause destabilization flag Fb are set to OFF (S116).

If the previous time and this time are in the stable region, or if the previous time and this time are not in the stable region (no in S114), the present process is temporarily exited. That is, the states of the flags Fa and Fb do not change.
Next, the engine warming-up engine stabilization control process (FIG. 3) performed based on the states of the two flags Fa and Fb will be described.

  When this process is started, it is first determined whether or not the ignition significant retard is being performed when the exhaust purification catalyst is warmed up (S122). If the ignition timing is not significantly retarded (NO in S122), the process is temporarily exited.

  If the ignition timing is greatly retarded due to warming up of the exhaust purification catalyst (yes in S122), it is next determined whether or not the intake air amount-induced destabilization flag Fa is ON (S124). ). If Fa = ON (yes in S124), it is next determined whether or not the intake air amount guard is being performed (S126). When the intake air amount-induced instability flag Fa is ON, it is necessary to increase the intake air amount in order to return the engine operating state to the stable region. However, in the case of idling or the like, if the intake air amount upper limit at idling has already been reached, the intake air amount is guarded against further increase (yes in S126), so the intake air amount is increased. It is not possible, and this processing is temporarily exited as it is.

  If the intake air amount is not being guarded (NO in S126), a process of returning the operating state of the engine 2 to the stable region by controlling the throttle opening degree TA is performed (S128). Actually, it is performed by increasing the throttle opening degree TA. This increase may be a constant opening increase for each control cycle, or may be an increase corresponding to the opening corresponding to the difference between the intake air amount reduction line La and the current engine speed NE for each control cycle. Thus, the present process is temporarily exited.

  If Fa = OFF (no in S124), it is determined whether or not the combustion state-induced instability flag Fb is ON (S130). If Fb = ON (yes in S130), it is next determined whether or not the ignition timing guard is being performed (S132). When the combustion state-induced instability flag Fb is ON, it is necessary to return the ignition timing that has been greatly retarded to the advance side. However, there is a limit also in the case of the ignition timing advance, and when the ignition timing guard that has set this limit has been reached, the ignition timing guard is in progress (yes in S132), so the advance of the ignition timing is It is not possible, and this processing is temporarily exited as it is.

  If the ignition timing guard is not underway (no in S132), a process for returning the engine operating state to the stable region is performed by the ignition timing control and the accompanying fuel injection timing control (S134). Actually, it is performed by the ignition timing advance and the accompanying fuel injection timing advance. This advance angle may be an advance angle of a constant crank angle for each control cycle. An advance angle corresponding to the crank angle corresponding to the distance between the combustion deterioration line Lb and the current position in the two-dimensional space may be used for each control cycle. Note that the advance of the fuel injection timing is performed in order to ensure an appropriate fuel concentration distribution state in the combustion chamber during the period until ignition. Thus, the present process is temporarily exited.

  In addition, about the engine 2 which returned to the stable area | region by step S128 or step S134, it will return to the control before entering into a destabilization area | region. For example, when the cold idle control is executed, the throttle opening degree TA is controlled so that the cold idle target rotational speed is realized.

  Even when ignition is greatly retarded during warming-up of the exhaust purification catalyst (yes in S122), both the intake air amount-induced destabilization flag Fa and the combustion state-induced destabilization flag Fb are both OFF. (No in S124, no in S130), the engine stabilization control process during catalyst warm-up (FIG. 3) does not perform a substantial process.

  In the above-described configuration, the relationship with the claims is that the combination of the intake pressure sensor 26, the engine speed sensor 24, and the EG-ECU 16 corresponds to the internal combustion engine operation state detection means, and the EG-ECU 16 is the internal combustion engine operation instability region. It corresponds to a setting means and a region corresponding internal combustion engine stabilization processing means. Step S102 of the unstable state determination process (FIG. 2) is the process as the internal combustion engine operation instability area setting means, and steps S104 to S112 and the engine warming-up engine stabilization control process (FIG. 3) are the area-corresponding internal combustion engine. This corresponds to processing as stabilization processing means.

According to the first embodiment described above, the following effects can be obtained.
(I). In the two-dimensional space of the engine speed NE and the load (specifically, the load factor KL) shown in FIG. 4, the intake air amount destabilization region below the intake air amount decrease line La and the combustion deterioration line Lb. The lower right combustion state-induced instability region is set. When the operation state of the engine 2 enters these destabilization regions (yes in S106, S108, or yes in S110, S112), processing to exit from each destabilization region is executed (FIG. 3).

  That is, the control related to the intake air amount, in this case, the control of the throttle opening TA (S128) is executed in order to get out of the intake air amount-induced instability region, so that an increase in rotation can be appropriately realized and a stable engine You can return to driving.

  Combustion-related control, in this case ignition timing control and fuel injection timing control, is executed in order to exit the instability region due to combustion state (S134), so that combustibility can be improved appropriately and stable. It can be returned to engine operation.

  If the control related to combustibility is executed as in step S134 in order to exit from the intake air amount-induced instability region, the intake air amount is not sufficiently supplied, and there is a delay in returning to stable engine operation. The unstable state may remain unimproved.

  The reverse is also true, and if the intake air amount is increased by controlling the throttle opening degree TA as in step S128 in order to come out of the instability region due to the combustion state, the ignition timing and fuel injection timing are greatly retarded. As a result, proper combustion is not performed. Therefore, there is a possibility that a delay may occur in returning to a stable engine operation or instability may not be improved.

  As described above, in this embodiment, when the ignition timing for retarding the exhaust purification catalyst is greatly retarded, the instability factor is determined based on the instability region as described above, and this instability region is determined. Since the corresponding appropriate processing is executed, it is possible to appropriately return from an unstable engine operation state to a stable operation state.

  (B). When the engine operating state becomes unstable, the engine operating state tends to first enter an instability region corresponding to the corresponding driving instability factor. Therefore, when the destabilization regions overlap as shown in the relationship between the intake air amount destabilization region and the combustion state destabilization region shown in FIG. 4, the lines La and Lb of the destabilization regions are overlapped. The first destabilized region is judged by crossing first. Then, by performing the internal combustion engine stabilization process for the first destabilized region, it is possible to appropriately execute the process of exiting the corresponding destabilized region.

  (C). As described above, the region of the intake pipe negative pressure (intake pressure PIM) that is insufficient with respect to the brake assist is set to overlap with the combustion state-induced instability region, so that the brake assist force Insufficiency can also be prevented.

[Other embodiments]
(A). In the first embodiment, the unstable state determination and the engine stabilization process by the unstable state determination process (FIG. 2) and the engine warming-up engine stabilization control process (FIG. 3) did not select the combustion mode. However, the process shown in FIGS. 2 and 3 may be executed only during the weak stratified combustion because it tends to deviate from the stable region shown in FIG. 4 during the weak stratified combustion.

  (B). In the first embodiment, when the vehicle passes through the intersection C and exits from the stable region, it has been set in advance so as to determine whether the combustion state is unstable or the intake air amount is unstable. . Instead, as shown in FIG. 5, the passage of the intersection C where the engine speed NE decreases and the load factor KL increases increases the combustion state instability, and the engine speed NE and the load factor KL are Passing through the intersection point C, which decreases together, may cause instability due to the intake air amount.

1 is a system configuration diagram of a vehicle internal combustion engine and a control device thereof according to Embodiment 1. FIG. 6 is a flowchart of an unstable state determination process executed by the EG-ECU of the first embodiment. The flowchart of engine stabilization control processing at the time of catalyst warm-up similarly. 2 is a two-dimensional space state explanatory diagram of an engine load factor KL and an engine speed NE used in the first embodiment. FIG. The two-dimensional space state explanatory drawing explaining the unstable state determination in other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Engine, 4 ... Torque converter, 6 ... Automatic transmission, 6a ... Output shaft, 8 ... Fuel injection valve, 10 ... Electric motor, 12 ... Intake pipe, 14 ... Throttle valve, 16 ... EG-ECU, 18 ... VSC- ECU, 19 ... Water temperature sensor, 20 ... Accelerator opening sensor, 21 ... Vehicle speed sensor, 22 ... Throttle opening sensor, 24 ... Engine speed sensor, 26 ... Intake pressure sensor, 28 ... Surge tank, 30 ... Atmospheric pressure sensor, 31 ... Air-fuel ratio sensor, 32 ... Brake pedal, 34 ... Brake switch, 36 ... Brake booster, 36a ... Diaphragm, 36b, 36c ... Pressure chamber, 36d ... Check valve, 36e ... Negative pressure control valve, 36f ... Spring, 36g ... Push rod, 36h ... Master cylinder, 36i ... Input side rod, 38 ... Brake block Star pressure sensor, 40 ... exhaust pipe, 42 ... catalytic converter, 44 ... Ignition system, 44a ... spark plug.

Claims (6)

An internal combustion engine control device at the time of ignition timing significant retard control for warming up a catalyst for exhaust gas purification of an internal combustion engine,
Intake air amount-induced instability region indicating instability of operation due to insufficient intake air amount of the internal combustion engine and the combustion state of the internal combustion engine in a two-dimensional space represented by the rotation speed and load of the internal combustion engine as parameters an internal combustion engine operating instability region setting means for setting the combustion state due unstable area as a destabilizing regions oPERATION destabilizing results of an internal combustion engine showing the operation destabilization due to deterioration,
An internal combustion engine operating state detecting means for detecting an operating state of the internal combustion engine;
The operating state of the internal combustion engine detected by the internal combustion engine operating state detection means is the intake air amount-induced instability region set by the internal combustion engine operation instability region setting means and the combustion state-initiated state. When entering the destabilization region of the intake air amount destabilization region or the combustion state destabilization region from a region other than the stabilization region , the corresponding destabilization region A region corresponding internal combustion engine stabilization processing means for executing processing to exit from the instability region in the internal combustion engine stabilization processing ,
The region corresponding internal combustion engine stabilization processing means increases the intake air amount of the internal combustion engine as the internal combustion engine stabilization processing when the operating state of the internal combustion engine enters the instability region caused by the intake air amount. When the operation state of the internal combustion engine enters the instability region due to the combustion state while the process of exiting from the instability region due to the intake air amount is performed, the ignition of the internal combustion engine is performed as the internal combustion engine stabilization processing. Execute processing to exit from the combustion state-induced instability region by advancing the timing
An internal combustion engine control apparatus according to claim and this. The internal combustion engine stabilization processing means according to claim 1, wherein when executing the processing to exit from the corresponding instability region, the instability region in which the operating state of the internal combustion engine first enters is subjected to the corresponding instability. An internal combustion engine control apparatus that executes processing out of the instability region in an internal combustion engine stabilization processing corresponding to the region as a region. 3. The in-cylinder fuel supply system according to claim 1, wherein the in-cylinder fuel supply system includes an in-cylinder fuel supply system that injects fuel into a combustion chamber, and the in-cylinder fuel supply system is in an unstable state due to the combustion state. When the fuel injection is performed in the compression stroke, the internal combustion engine stabilization processing means corresponds to the advance of the ignition timing and the advance of the ignition timing as the internal combustion engine stabilization processing. An internal combustion engine control apparatus characterized by advancing a fuel injection timing. The internal combustion engine according to any one of claims 1 to 3 , wherein the internal combustion engine is an internal combustion engine for a vehicle, the intake negative pressure of the internal combustion engine is used for brake assist, and the combustion state-induced instability region is insufficient for brake assist. An internal combustion engine control device characterized by being set to overlap with an intake pipe negative pressure region. In any one of claims 1 to 4, wherein the intake air amount due destabilization region internal combustion engine control apparatus characterized by being set by an upper limit due to the rotation speed of the internal combustion engine. In any one of claims 1 to 5, the internal combustion engine has one combustion mode of stratified charge combustion, the region corresponding engine stabilization processing means only during the weak stratified charge combustion, the engine operating condition The operating state of the internal combustion engine detected by the detecting means enters one of the destabilization areas from areas other than all the destabilization areas set by the internal combustion engine operation destabilization area setting means. In this case, the internal combustion engine control apparatus is configured to execute a process of exiting the instability region in the internal combustion engine stabilization processing corresponding to the instability region.

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