JP2002371884A - Combustion controller for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with dedicated data for determining pumping loss during a delay period in a case when the control parameter of a fuel system and an ignition system is switched from the stratified charge combustion to the homogeneous combustion, after the control parameter of an intake system is switched from the stratified charge combustion to the homogeneous combustion. SOLUTION: In the delay period, a ratio of the change of an actual intake pressure epmfwd from the start of the delay period, in the difference between an initial intake pressure epmfwdl and a virtual intake pressure epmfwdmd is determined as a correction coefficient KPMD (S250). An increase correction value dkq is determined on the basis of the correction coefficient KPMD (S270). A dedicated map and the like corresponding to an engine operating condition is not unnecessary in determining the increase correction value dkq, which dispenses with the operation for matching the dedicated map and the like for every engine, and realizes the efficient development of an internal combustion engine control system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of switching the combustion mode of an internal combustion engine from stratified charge combustion to homogeneous charge combustion by switching control parameters of an intake system from values suitable for stratified charge combustion to values suitable for homogeneous charge combustion. The present invention relates to an internal combustion engine combustion control device that switches control parameters of a fuel system and an ignition system after a delay period from values suitable for stratified combustion to values suitable for homogeneous combustion.

[0002]

2. Description of the Related Art An internal combustion engine control system has been proposed in which the combustion mode is switched between homogeneous combustion and stratified combustion in accordance with the operating state in order to achieve both improved fuel economy and sufficient engine output (Japanese Patent Application No. 2002-287,197). 2000-176657). In this internal combustion engine control system, control parameters of the intake system are preceded by control parameters of the fuel system and the ignition system in consideration of the delay of the intake system when switching the combustion mode, particularly when switching from stratified combustion to homogeneous combustion. After the delay period has elapsed, the control parameters of the fuel system and the ignition system are switched from stratified combustion to values suitable for homogeneous combustion.

[0003] During this delay period, stratified combustion is performed. However, pumping loss increases due to a gradual decrease in intake pressure despite stratified combustion during this period. By increasing the fuel injection amount, the pumping loss is compensated to prevent the output torque from lowering.

[0004]

In the conventional internal combustion engine control system described above, the fuel increase correction amount for compensating for such pumping loss is gradually increased during the intake pressure at the start of the delay period and during the subsequent delay period. The calculation is based on the differential pressure from the descending intake pressure. In order to calculate the pumping loss from the differential pressure data, it is necessary to convert the pumping loss into a pumping loss using a conversion coefficient. Engine speed) must be used.

[0005] However, creating dedicated data such as a map requires a lot of labor. In addition, every time the internal combustion engine is changed in specifications, it is necessary to spend a great deal of effort re-adapting the dedicated data for conversion, so the use of such dedicated data has led to the efficient development of an internal combustion engine control system. It has become a hindrance.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to efficiently develop an internal combustion engine control system by eliminating the need for dedicated data for determining pumping loss.

[0007]

The means for achieving the above object and the effects thereof will be described below. In the internal combustion engine combustion control device according to the first aspect, when switching the combustion mode of the internal combustion engine from stratified combustion to homogeneous combustion, the control parameter of the intake system is switched from a value suitable for stratified combustion to a value suitable for homogeneous combustion. An internal combustion engine combustion control device that switches control parameters of the fuel system and the ignition system from a value suitable for stratified combustion to a value suitable for homogeneous combustion after a delay period from the start of the delay period during the delay period. Based on the ratio of the change in the intake pressure equivalent value to the difference between the intake pressure equivalent value at the start of the delay period and the intake pressure equivalent value expected when performing homogeneous combustion in the operating state during the delay period. A fuel increase correction means for obtaining a fuel increase value by performing a fuel increase correction for pumping loss compensation.

As described above, in the present invention, the pumping loss is not simply compensated for by calculating the change in the intake pressure equivalent value from the start of the delay period. In the present invention, the fuel increase correction means executes the homogeneous combustion in the intake pressure equivalent value at the start of the delay period and the operating state during the delay period by the change in the intake pressure equivalent value from the start of the delay period during the delay period. In this case, the fuel increase value is determined based on the ratio of the difference to the expected intake pressure equivalent value. This ratio indicates the degree of progress of the change in the intake pressure equivalent value until switching from stratified combustion to homogeneous combustion. For this reason, the fuel increase correction means
Fuel increase correction for pumping loss compensation can be performed based on this ratio.

When this ratio is used, a fuel increase value for pumping loss compensation can be obtained without using a dedicated map for conversion or the like to adapt to the operating state of the internal combustion engine. Therefore, it is possible to efficiently develop an internal combustion engine control system without requiring dedicated data for conversion.

Here, the control parameters of the intake system mean parameters for controlling the intake system such as a target throttle opening and a target opening of the exhaust gas recirculation valve. Means a parameter for controlling a fuel system such as a fuel injection timing and a fuel injection amount, and a control parameter of an ignition system means a parameter for controlling an ignition system such as an ignition timing. The intake pressure equivalent value represents a value expressing the degree of the intake pressure, and is a concept including the intake pressure itself, the intake air amount per rotation, and the like. The same applies hereinafter.

In the internal combustion engine combustion control device according to the second aspect, in the configuration according to the first aspect, the fuel increase correction means includes an actual intake pressure equivalent value PMA at the start of the delay period; Based on the actual intake pressure equivalent value PMB and the intake pressure equivalent value PMC expected when homogeneous combustion is performed in the operating state during the delay period, a calculation formula (PMA-PMB) / (PMA-PM)
C), a coefficient KPMD for the fuel increase correction is calculated as the ratio.

More specifically, the above equation (PMA-P
A coefficient KPMD for fuel increase correction is obtained from the value of (MB) / (PMA-PMC), and fuel increase is performed using the coefficient KPMD. By using the coefficient KPMD, a fuel increase value for pumping loss compensation can be obtained without using a dedicated map for conversion or the like to adapt to the operating state of the internal combustion engine. Therefore, it is not necessary to use dedicated data for conversion, and it is possible to efficiently develop an internal combustion engine control system.

According to a third aspect of the present invention, in the internal combustion engine combustion control apparatus according to the first or second aspect, the fuel increase correction means includes an internal combustion engine load QB during stratified combustion obtained from an operation state during the delay period. And a difference between an expected internal combustion engine load QC during homogeneous combustion when the homogeneous combustion is performed in the operating state during the delay period and the ratio or the coefficient KPMD to obtain a fuel increase value, It is characterized in that the supplied fuel amount is increased and corrected based on the fuel increase value.

More specifically, the ratio or coefficient KP is added to the difference between the internal combustion engine load QB and the internal combustion engine load QC.
The fuel increase value can be obtained by multiplying the MD, and the supply fuel amount can be increased and corrected with the fuel increase value. As a result, without using a dedicated map for conversion or the like to adapt to the operating state of the internal combustion engine,
A fuel increase value for pumping loss compensation can be obtained. Therefore, it is not necessary to use dedicated data for conversion, and it is possible to efficiently develop an internal combustion engine control system.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 shows a direct injection gasoline engine (hereinafter abbreviated as "engine") 2 mounted on a vehicle and an electronic control unit (hereinafter, referred to as "engine").
This shows the schematic configuration of an ECU 4). The output of the engine 2 is finally transmitted to the wheels as a driving force for driving via a transmission (not shown). The engine 2 is provided with a fuel injection valve 12 for directly injecting fuel into the combustion chamber 10 and an ignition plug 14 for igniting the injected fuel. An intake port 16 connected to the combustion chamber 10 is opened and closed by driving an intake valve 18. A surge tank 22 is provided in the middle of the intake passage 20 connected to the intake port 16, and a throttle valve 26 whose opening is adjusted by a throttle motor 24 is provided upstream of the surge tank 22. The amount of intake air is adjusted based on the opening of the throttle valve 26 (throttle opening TA). The throttle opening TA is detected by a throttle opening sensor 28, and the intake pressure PM in the surge tank 22 is determined by an intake pressure sensor 3 provided in the surge tank 22.
0 is detected and read into the ECU 4.

Exhaust port 32 connected to combustion chamber 10
Is opened and closed by driving the exhaust valve 34. In the middle of the exhaust passage 36 connected to the exhaust port 32, a three-way catalyst or N
An exhaust purification catalyst 38 such as an Ox storage reduction catalyst is provided. An exhaust gas recirculation (hereinafter, referred to as “EGR”) passage 40 is formed from the exhaust passage 36 to the intake passage 20, and the ECU 4 controls the EGR valve 42 to recirculate gas from the exhaust passage 36 to the intake passage 20. The amount (EGR amount) is adjusted.

The ECU 4 is an engine control circuit mainly composed of a digital computer. This EC
U4 is a throttle opening sensor 28, an intake pressure sensor 30
In addition to the above, a signal from an accelerator opening sensor 46 that detects the amount of depression of an accelerator pedal 44 (accelerator opening ACCP) is input. The ECU 4 includes a rotation speed sensor 50 for detecting the engine speed NE from the rotation of the crankshaft 48 and a reference crank angle sensor 52 for determining a reference crank angle from the rotation of the intake camshaft (not shown).
Is inputting a signal from Although not shown, an air-fuel ratio sensor for detecting the air-fuel ratio of the air-fuel mixture from the exhaust gas components in the exhaust passage 36 and other sensors are provided as necessary in addition to the above sensors.

The ECU 4 appropriately controls the fuel injection timing, the fuel injection amount, the throttle opening and the like of the engine 2 based on the detection contents from the various sensors described above. As a result, the combustion mode is switched between stratified combustion and homogeneous combustion. In the first embodiment, the combustion mode is determined based on the map of the engine speed NE and the load factor eklq during the normal operation excluding the state such as the cold state, as shown in FIG. Here, the load factor eklq is a value corresponding to the fuel injection amount, and indicates the ratio of the current load to the maximum engine load based on the accelerator opening ACCP and the engine speed NE. This is a value obtained from a map using the engine speed NE as a parameter.

When the combustion mode is set to stratified combustion, the throttle valve 26 is almost fully opened irrespective of the degree of the accelerator opening ACCP, and an amount of fuel considerably smaller than the stoichiometric air-fuel ratio is supplied in the latter half of the compression stroke. It is controlled to be injected. As a result, at the ignition timing, stratified combustion is performed by igniting the ignitable rich air-fuel mixture present in a stratified form near the ignition plug 14.

On the other hand, when the combustion mode is set to homogeneous combustion, the opening of the throttle valve 26 is adjusted in accordance with the degree of the accelerator opening ACCP, and the amount of the stoichiometric air-fuel ratio (in some cases, the stoichiometric air-fuel ratio is reduced). The fuel is controlled to be injected during the intake stroke. As a result, at the ignition timing, a homogeneous air-fuel mixture having a stoichiometric air-fuel ratio occupying the entire inside of the combustion chamber 10 (in some cases richer than the stoichiometric air-fuel ratio) is ignited, and homogeneous combustion is performed.

Next, among the controls executed by the ECU 4, a mode switching control process from stratified combustion to homogeneous combustion will be described. FIG. 3 shows a flowchart of the process. This process is a process that is repeatedly executed in a time cycle or a crank angle cycle after a request for switching the combustion mode from stratified combustion to homogeneous combustion is issued. Steps in the flowchart corresponding to each processing content are denoted by “S
~ ".

When the operating state changes from the stratified combustion region to the homogeneous combustion region based on the map of the engine speed NE and the load factor eklq shown in FIG. 2, a request for switching the combustion mode from stratified combustion to homogeneous combustion occurs. Then, the present process is started. First, the EGR valve 4 is set so that the EGR valve 42 is fully closed.
A second target opening is set (S110). With this setting, the EGR valve 42 is immediately closed, so that the exhaust gas in the exhaust passage 36 is not supplied to the intake passage 20 via the EGR passage 40.

Next, it is determined whether or not the waiting period has elapsed (S115). This standby period is a period in which the EGR valve 42 is fully closed, and the supply of exhaust gas that has been supplied from the EGR passage 40 is stopped.
This is the period to wait until the intake pressure stabilizes,
It is counted from the time when the EGR valve 42 is set to fully closed.
The length of the standby period is set based on, for example, the opening degree of the EGR valve 42 immediately before the combustion mode is switched to the homogeneous combustion.

Since the waiting period has not elapsed at first (S
If “NO” at 115), the present process is ended once. The above-described processing is repeated until the waiting period elapses. When the standby period has elapsed (“YES” in S115), it is determined whether the process is the first process after the standby period has elapsed (S115).
120). If it is the first process ("YE" in S120)
S "), the throttle opening is changed from the adjustment for stratified combustion to the adjustment for homogeneous combustion (S125). Thus, in the throttle opening control separately executed by the ECU 4, the target throttle opening, which is a control parameter of the intake system, is switched to a value suitable for homogeneous combustion. Specifically, the throttle opening TA is controlled by the throttle motor 24 so as to correspond to the accelerator opening ACCP, so that the throttle opening TA is closed more than during stratified combustion in a state near full open.

Next, the engine speed NE and the load factor ek
A delay period DT is set from a map or the like based on lq (S130). This delay period DT is the same as that in step S1
25 represents a period from when the throttle opening degree control for homogeneous combustion is changed to 25 to when the intake pressure actually sucked into the combustion chamber 10 changes to a state suitable for homogeneous combustion or to a state close thereto. It is.

Next, in order to count the progress since the change to the throttle opening control for homogeneous combustion, a counter C
Is set to 0 (S135). Then, it is determined whether or not the counter C has exceeded the delay period DT (S14).
0). At first, since C <DT (“NO” in S140), the present process is temporarily ended.

In the next control cycle, since it is not immediately after the mode switching request to homogeneous combustion ("NO" in S120),
The value of the counter C is incremented (S145), and C
It is determined whether or not ≧ DT (S140). While the delay period DT has not elapsed, since C <DT (“NO” in S140), the present process is temporarily terminated. In this way, while C <DT, the increment of the value of the counter C (S145) is repeated every control cycle.

If C ≧ DT (“YES” in S140), the delay time DT has elapsed, and the ignition timing, fuel injection timing and fuel injection amount are then changed from the control for stratified charge combustion to the control for homogeneous charge combustion. (S150). As a result, the ignition timing control separately executed by the ECU 4,
In the fuel injection timing control and the fuel injection amount control, the control parameters of the fuel system and the ignition system are switched from values suitable for stratified combustion to values suitable for homogeneous combustion. Specifically, homogeneous combustion is realized by adjusting the fuel injection timing and the fuel injection amount so as to inject an amount of fuel corresponding to the intake air amount during the intake stroke, and the ignition timing is adjusted to match the homogeneous combustion. I do. Then, the end of this control processing is set (S155), and this processing ends. After this,
The control process (FIG. 3) is not executed until a mode switching request from stratified combustion to homogeneous combustion is generated.

As described above, in the mode switching control process from stratified combustion to homogeneous combustion (FIG. 3), the throttle opening is changed to the adjustment for homogeneous combustion (S125).
The fuel increase correction performed during the change of the ignition timing, the fuel injection timing, and the fuel injection amount to the control for homogeneous combustion after the delay period DT (S150) will be described with reference to FIG.

The fuel increase correction amount calculation process during this delay period (FIG. 4) is a process that is repeatedly executed in the same cycle as the mode switching control process from stratified combustion to homogeneous combustion (FIG. 3). When the process is started, first, it is determined whether or not a delay period is currently in progress (S210). For example, if the counter C satisfies C <DT and is counting up, it is determined that a delay period is in progress. If it is not during the delay period ("NO" in S210), the present process is temporarily ended as it is.

On the other hand, if it is during the delay period ("YES" in S210), it is determined whether or not the processing is the first processing (S22).
0). If it is the first ("YES" in S220), then
The actual intake pressure epmfwd (corresponding to the intake pressure equivalent value PMB) is set as the initial intake pressure epmfwdl (corresponding to the intake pressure equivalent value PMA) (S230). Here, the actual intake pressure e
pmfwd is the intake pressure P measured by the intake pressure sensor 30.
A value calculated by predicting the intake pressure when the intake valve 18 is closed based on M, the throttle opening, and the engine speed NE is used. Note that the actual intake pressure PM measured by the intake pressure sensor 30 may be used instead of the actual intake pressure epmfwd.

Next, a virtual intake pressure epmfwdmd (intake pressure equivalent value PM
C) (S240). This virtual intake pressure e
pmfwdmd calculates a throttle opening that is predicted to be set in the case of homogeneous combustion based on the value of the accelerator opening ACCP during the present stratified combustion, and calculates the throttle opening and the engine speed NE based on the predicted throttle opening and the engine speed NE. This is the predicted intake pressure. That is, it indicates the intake pressure when the homogeneous combustion is assumed under the same operation state as that in the stratified combustion. The virtual intake pressure epmfwdmd is a value that is always calculated by the ECU 4 even during stratified combustion for control purposes. Therefore, it is only necessary to read that value in step S240.

Then, a correction coefficient KPMD is calculated as in the following equation 1 (S250).

[0034]

KPMD ← (epmfwdl-epmfwd) / (epmfwdl-epmfwmd) (Equation 1) In Equation 1, during the delay period, the change in the actual intake pressure epmfwd from the start of the delay period is the start of the delay period. It shows the ratio of the difference between the intake pressure at the time (initial intake pressure epmfwdl) and the intake pressure (virtual intake pressure epmfwdmd) expected when executing the homogeneous combustion in the operating state during the delay period.

Next, the virtual load factor eklfwdmd (corresponding to the internal combustion engine load QC during homogeneous combustion) is read (S26).
0). The virtual load factor eklfwdmd is obtained by the product of the virtual intake pressure epmfwdmd and the charging efficiency, and is a value that is always calculated by the ECU 4 even during stratified combustion for control. In step S260, the virtual load ratio eklfwdmd may be calculated based on the product of the virtual intake pressure epmfwdmd read in step S240 and the charging efficiency.

Then, as shown in the following equation 2, an increase correction value dkq is calculated (S270).

[0037]

Dkq ← (eklfwdmd−eklq) × KPMD (Equation 2) That is, by using the correction coefficient KPMD, the degree of progress of the intake pressure change until switching from stratified combustion to homogeneous combustion can be calculated by using Expression 2. The increase correction value dkq is determined by reflecting the difference (eklfwdmd-eklq) between the virtual load factor eklfwdmd and the current load factor eklq (corresponding to the internal combustion engine load QB during stratified combustion). Thus, the present process is once ended.

The gain correction value dk obtained in this manner is obtained.
q is added to the load factor eklq as in the following equation 3 in the fuel injection amount control process separately executed by the ECU 4.

[0039]

Eklq ← eklq + dkq (Equation 3) By increasing the load factor in this way, the fuel injection amount set based on the load factor eklq is increased in accordance with the increase correction value dkq. Will be.

An example of the above control is shown in the timing chart of FIG. Before time t0, the combustion mode request is assumed to be stratified combustion, and at time t0, the combustion mode request is changed to homogeneous combustion. At this time, the EGR valve 42 is simultaneously fully closed. Then, at time t1 after the elapse of the standby period, the throttle control mode changes to homogeneous combustion. As a result, the throttle opening TA becomes smaller than the accelerator opening ACCP.
The actual intake pressure epmfwd
Gradually decreases. Regarding the fuel injection control and the ignition control, in the control mode, the stratified combustion mode is continued until the delay period DT elapses from the time t1 (time t3). Therefore, stratified combustion continues in the actual combustion mode from the time t1 to the elapse of the delay period DT.

During the delay period DT, for example, at time t2
In this case, although the stratified combustion is used, the throttle opening TA itself has already been reduced for homogeneous combustion, so the actual intake pressure epmfw
d is lower than the intake pressure required during stratified combustion. For this reason, a pumping loss due to the reduced amount dPA occurs. In order to compensate this pumping loss by combustion energy, the initial intake pressure epmf at time t1 is set.
wdl and the virtual intake pressure epmfwdm at time t2
The difference dPB from d is calculated, and the ratio of the decrease dPA to the difference dPB (the correction coefficient KPMD) is calculated.

At time t2, the load factor eklq (before correction) suitable for stratified combustion and the virtual load factor eklf
wdmd is obtained. Therefore, the difference d between the pre-correction load factor eklq and the virtual load factor eklfwdmd
At time t2, KB is proportionally distributed by the ratio of the decrease dPA to the difference dPB (the correction coefficient KPMD).
Is obtained as an underload factor dKA (increase correction value dkq) corresponding to the pumping loss in the above. This underload factor dK
A (increase correction value dkq) is added to the load factor eklq before correction.
, It is possible to set a load factor eklq that compensates for pumping loss and does not cause a step in output torque.

In the example of FIG. 5, the delay period DT ends before the pumping loss reaches 100% of the pumping loss in the homogeneous combustion (time t3). At this time, the control mode of the fuel injection control and the ignition control is performed. Is set to transition to homogeneous combustion. Therefore, from time t3, the combustion mode becomes homogeneous combustion. Therefore, as indicated by hatching from time t3, a state where the load factor eklq during homogeneous combustion is slightly larger than the pumping loss temporarily occurs.
For this reason, the process of reducing the output torque by the ignition timing retarding process is temporarily executed.

In the configuration described above, the fuel increase correction amount calculation process (FIG. 4) during the delay period corresponds to a process as a fuel increase correction means. According to the first embodiment described above, the following effects can be obtained.

(A). During the delay period, the ratio of the change in the actual intake pressure epmfwd from the start of the delay period to the difference between the initial intake pressure epmfwdl and the virtual intake pressure epmfwdmd is determined as the correction coefficient KPMD. Then, the virtual load factor eklfwdmd and the current load factor ek
The increase correction value dkq is obtained by multiplying the value of the difference from 1q by the correction coefficient KPMD.

The correction coefficient KPMD indicates the degree of progress of the change in the intake pressure until switching from stratified combustion to homogeneous combustion, that is, the degree of pumping loss. For this reason, the virtual load factor eklfwdmd, which is the total pumping loss before switching from stratified combustion to homogeneous combustion, and the current load factor ek
By multiplying the difference from 1q by the correction coefficient KPMD, the increase correction value dkq for appropriately compensating the pumping loss during the delay period can be obtained.

Then, as described above, the increase correction value dk
In order to obtain q, there is no need for a dedicated map or the like corresponding to the operating state of the engine 2. Therefore, when the first embodiment is applied to various engines, there is no need to adapt dedicated data for converting a change in intake pressure for each engine, so that the efficient development of an internal combustion engine control system is eliminated. It can be performed.

[Second Embodiment] In the first embodiment,
In steps S250 to S270 of the fuel increase correction amount calculation process (FIG. 4) during the delay period, a correction coefficient KPMD is obtained based on the above equation 1 (S250), and this correction coefficient KPM
The increase correction value dkq was calculated based on D (S27).
0). However, the procedure for calculating the increase correction value dkq can be changed as appropriate.

In the second embodiment, the procedure for calculating the above-described fuel increase correction value dkq is modified, and step S25 of the fuel increase correction amount calculation process (FIG. 4) during the delay period is performed.
Embodiment 6 is different from Embodiment 1 in that the processing shown in FIG. 6 is executed instead of 0 to S270.

That is, in the fuel increase correction amount calculation process according to the second embodiment, after step S240 of the fuel increase correction amount calculation process during the delay period (FIG. 4), as shown in FIG. 6, the virtual intake pressure epmfwdmd is obtained. The virtual load ratio eklfwdmd obtained by multiplying the product of the load efficiency and the charging efficiency is read (S310). This process is the same as step S260, and in step S310, the virtual intake pressure epmfwd
The product of md and filling efficiency may be calculated.

Then, the correction coefficient KQ is calculated according to the following equation (S320).

[0052]

KQ ← (eklfwdmd-eklq) / (epmfwdl-epmfwmd) (Equation 4) This equation 4 is obtained by calculating the initial intake pressure epmfwdl and the virtual intake pressure e.
pmfwdmd and the virtual load factor eklfwdmd
The ratio of the difference between the current load factor eklq and the current
Is what you want.

Next, as shown in the following equation 5, the increase correction value d
kq is calculated (S330).

[0054]

Dkq ← (epmfwdl−epmfwd) × KQ (Equation 5) In the configuration described above, steps S250 to S270 of the fuel increase correction amount calculation process (FIG. 4) during the delay period are replaced as shown in FIG. The process corresponds to a process as a fuel increase correction unit.

According to the second embodiment described above, the same effects as in the first embodiment can be obtained. [Other Embodiments] In the first and second embodiments, the difference between the virtual load factor eklfwdmdd and the current load factor eklq is calculated by the expression “eklfwdmd−eklq” in Expressions 2 and 4. In addition to this, in order to convert the fuel injection amount during homogeneous combustion calculated as homogeneous combustion and the fuel injection amount during homogeneous combustion into the fuel injection amount during stratified combustion, A value instead of “eklfwdmd-eklq” may be calculated based on a preset conversion coefficient and used. Further, a difference in fuel injection amount and a difference in pumping loss may be calculated and used based on a difference in combustion efficiency between homogeneous combustion and stratified combustion.

In the first and second embodiments, as the detection data relating to the intake air, the intake pressure sensor is provided to detect the intake pressure, and is used to set the control parameters of the intake system. In addition, an intake air amount sensor is provided to detect the intake air amount, and an intake pressure equivalent value (for example, the intake air amount per engine revolution) is determined from the intake air amount to set the intake system control parameters. You may use it for.

In the first and second embodiments, when the combustion mode is switched from stratified combustion to homogeneous combustion, the EGR valve 42 is fully closed first, and the throttle valve is closed after the EGR amount has disappeared. The opening control of 26 was switched from stratified charge combustion to homogeneous charge combustion. Alternatively, full closing of the EGR valve 42 and switching of the opening control of the throttle valve 26 from stratified charge combustion to homogeneous charge combustion may be performed simultaneously without providing a standby time. In this way, in the processing shown in FIGS. 4 and 6, the pumping loss when switching the control of the EGR valve 42 and the throttle valve 26 from the stratified charge combustion to the homogeneous charge combustion can be compensated. It should be noted that, depending on the engine operating state, the combustibility may be improved due to the loss of the EGR amount. Therefore, when the EGR valve 42 and the throttle valve 26 are simultaneously switched to the homogeneous combustion control, a fuel correction relating to the combustibility may be further added according to the engine operating state. In this case, a more stable combustion mode switching process can be performed.

In the first and second embodiments, the internal combustion engine provided with the EGR passage 40 and the EGR valve 42 has been described. However, the present invention can be similarly applied to an internal combustion engine not provided with the EGR passage 40 and the EGR valve 42. Produces the same effect.

In FIG. 1, the EGR passage 40 supplies exhaust gas to the downstream of the surge tank 22. Alternatively, exhaust gas may be supplied to the surge tank 22, and the throttle valve 26 and the surge tank 22 The exhaust gas may be supplied in between.

[Brief description of the drawings]

FIG. 1 shows an engine and an ECU thereof according to a first embodiment.
FIG.

FIG. 2 is a map configuration diagram for setting a combustion mode executed by the engine.

FIG. 3 is a flowchart of a mode switching control process from stratified combustion to homogeneous combustion executed by the ECU.

FIG. 4 is a flowchart of a fuel increase correction amount calculation process during a delay period executed by the ECU.

FIG. 5 is a timing chart showing an example of control according to the first embodiment.

FIG. 6 is a flowchart showing a part of a fuel increase correction amount calculation process during a delay period performed in a second embodiment.

[Explanation of symbols]

2 engine, 4 ECU, 10 combustion chamber, 12 fuel injection valve, 14 spark plug, 16 intake port, 18
Intake valve, 20: intake passage, 22: surge tank, 2
4: Throttle motor, 26: Throttle valve, 28
... Throttle opening sensor, 30 ... Intake pressure sensor, 32 ...
Exhaust port, 34: Exhaust valve, 36: Exhaust passage, 38
... exhaust gas purifying catalyst, 40 ... EGR passage, 42 ... EGR valve,
44: accelerator pedal, 46: accelerator opening sensor, 4
Reference numeral 8 denotes a crankshaft, 50 denotes a rotation speed sensor, and 52 denotes a reference crank angle sensor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02P 5/15 F02P 5/15 B F-term (Reference) 3G022 AA07 FA06 GA02 GA05 GA07 GA08 3G084 AA04 BA05 BA09 BA13 BA15 BA17 BA20 DA25 EA07 EA11 EB08 FA10 FA11 FA18 FA29 FA33 FA37 FA38 3G301 HA04 HA16 LA00 LA01 LA03 LB04 MA01 MA11 MA19 NA08 NB02 NC02 NC08 ND02 NE01 NE13 NE22 NE23 PA07Z PA08Z PA11Z PA19 PD03Z PD15Z PE01Z PE04Z PF03

Claims (3)

[Claims] When a combustion mode of an internal combustion engine is switched from stratified combustion to homogeneous combustion, a control parameter of an intake system is switched from a value suitable for stratified combustion to a value suitable for homogeneous combustion, and after a delay period, the fuel system and the fuel system are switched. An internal combustion engine combustion control device that switches a control parameter with an ignition system from a value suitable for stratified combustion to a value suitable for homogeneous combustion, wherein a change in an intake pressure equivalent value from the start of the delay period during the delay period. The fuel increase value is determined based on the ratio of the intake pressure equivalent value at the start of the delay period and the intake pressure equivalent value expected when performing homogeneous combustion in the operating state during the delay period, An internal combustion engine combustion control device comprising: a fuel increase correction means for performing a fuel increase correction for pumping loss compensation. 2. The system according to claim 1, wherein said fuel increase correction means includes: an actual intake pressure equivalent value PMA at the start of said delay period; an actual intake pressure equivalent value PMB during said delay period; Intake pressure equivalent value PM expected when homogeneous combustion is performed in the operating state during the delay period
C, the calculation formula (PMA-PMB) / (PMA
-PMC), a coefficient KPMD for the fuel increase correction is obtained as the ratio as the ratio. 3. The fuel supply system according to claim 1, wherein the fuel increase correction means changes the internal combustion engine load QB during stratified combustion determined from an operation state during the delay period and an operation state during the delay period. The difference from the expected internal combustion engine load QC during homogeneous combustion when homogeneous combustion is performed is as follows:
An internal combustion engine combustion control apparatus characterized in that a fuel increase value is obtained by multiplying the ratio or the coefficient KPMD, and the supply fuel amount is increased and corrected based on the fuel increase value.