JPH09195839A - Apparatus for controlling combustion of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a misfire at the time of switching a combustion state in an internal combustion engine in which switching of a stratified combustion and a homogeneous combustion can be carried out. SOLUTION: When a combustion state distinguishing region is switched, an electronic controlling unit (ECU 30) controls also an actuator of an air intake system (step motors 19, 22 and EGR value 53) following the switching. For example, the open degree of a step valve 23, the open degree of swirl control valve 17, and the open degree of the EGR valve 53 are immediately controlled in the case stratified combustion is switched to a homogeneous combustion. ON the contrary, ECU 30 carries out the switching of the controlling contents of the fuel injection control and the ignition (timing) control slightly later than the switching of the control contents of a gas intake system. Consequently, that the gas intake state can not be switched immediately following the switching between respective combustion state can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control apparatus for an internal combustion engine, and more particularly, to a combustion control apparatus for a direct injection type internal combustion engine.
The present invention relates to a combustion control device for an internal combustion engine capable of performing stratified combustion.

[0002]

2. Description of the Related Art Conventionally, in a commonly used engine, fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is previously supplied to a combustion chamber. In such an engine, an intake passage is opened and closed by a throttle valve linked to an accelerator operation, and by this opening and closing, the amount of intake air supplied to a combustion chamber of the engine (consequently, a gas mixture in which fuel and air are homogeneously mixed). ) Is adjusted, thereby controlling the engine output.

[0003] However, in the technique based on the so-called homogeneous combustion described above, a large intake negative pressure is generated in accordance with the throttle operation of the throttle valve, and the pumping loss increases to lower the efficiency. On the other hand, by reducing the throttle valve throttle and supplying fuel directly to the combustion chamber, a combustible mixture is made to exist in the vicinity of the spark plug, and the air-fuel ratio of that part is increased to improve ignitability. So-called "stratified combustion"
That technology is known.

For example, in the technique disclosed in Japanese Patent Laid-Open No. 60-67721, fuel is directly injected into the combustion chamber (in-cylinder injection type). When the load is low, the fuel is unevenly distributed around the spark plug to be supplied and ignited to perform stratified combustion. On the other hand, when the load is high, the fuel is dispersed in the combustion chamber to be supplied and ignited to perform homogeneous combustion. Further, in this technique, a swirl is given to the intake air introduced into the combustion chamber, and the strength of the swirl is controlled according to homogeneous combustion and stratified combustion. By performing such control, combustion noise and knocking are prevented from occurring, intake efficiency is improved, and the like.

[0005]

However, the above-mentioned prior art has the following problems. For example, when the combustion state is switched from stratified combustion to homogeneous combustion, the fuel injection timing is actually switched, but even if the injection is switched in this way, it takes time for the airflow state to switch. I will end up. In other words, the required intake conditions in the stratified combustion and the homogeneous combustion (for example, the intake amount by the throttle opening, the swirl strength by the opening of the swirl control valve, the EGR amount by the opening of the exhaust gas recirculation valve (EGR valve)) They are different from each other, and when the combustion state is switched from stratified charge combustion to homogeneous combustion, the state of intake air is the state at the time of stratified charge combustion at the beginning of switching. Therefore, the state of intake air, and eventually the actual combustion cannot follow the switching, and as a result, there is a risk of causing misfire.

More specifically, in stratified charge combustion, a large amount of EGR gas is generally introduced. However, when homogeneous combustion is switched to in this state, the flame propagation property deteriorates due to too much EGR gas. , A misfire will occur.

[0007] Generally, in the stratified charge combustion, a moderate amount of fuel needs to be around the spark plug so that the swirl is weakened. However, when the homogeneous combustion is switched in this state, the swirl is too weak. A misfire will occur.

Further, in the stratified charge combustion, the opening of the electronically controlled throttle valve is set as large as possible in order to improve the fuel consumption. However, when the homogeneous combustion is switched in this state, the air-fuel ratio reaches the lean limit. It will exceed, and a misfire will occur.

As described above, when the stratified combustion is switched to the homogeneous combustion, the intake state cannot immediately follow the switching of each combustion, and as a result, there is a risk of causing misfire. It was Also, in the opposite case (when the homogeneous combustion is switched to the stratified combustion), there is a risk of misfire.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to prevent misfire during switching of combustion states in an internal combustion engine capable of switching control between stratified combustion and homogeneous combustion. An object of the present invention is to provide a combustion control device for an internal combustion engine capable of achieving the above.

[0011]

In order to achieve the above object, in the invention described in claim 1, as shown in FIG. 1, in order to perform stratified combustion and homogeneous combustion, the fuel is fed into the cylinder of the internal combustion engine M1. Fuel injection means M2 for injecting fuel and operating state detection means M3 for detecting the operating state of the internal combustion engine M1.
And a required combustion state determination means M4 for determining whether stratified combustion or homogeneous combustion is currently required based on the detection result of the operating state detection means M3, and the required combustion state determination means M4. Based on the determination result, the fuel injection means M2 is controlled to control the combustion state of the internal combustion engine M1 to be switched to stratified combustion or homogeneous combustion, and the detection result of the operating state detection means M3. Intake control means M6 for controlling intake air introduced into the internal combustion engine M1, fuel injection control means M7 for controlling fuel injection from the fuel injection means M2 based on the detection result of the operating state detection means M3, and Operating state detection means M
A combustion control device for an internal combustion engine, comprising: an ignition control means M8 for controlling ignition of the internal combustion engine M1 based on a detection result of No. 3, wherein when the combustion state is switched by the combustion control means M5, As compared with the switching of the control content by the intake control means M6, a switching delay means M9 for delaying and executing the switching of the control content by the fuel injection control means M7 and the control content by the ignition control means M8 is provided. There is.

According to a second aspect of the present invention, in the internal combustion engine combustion control device according to the first aspect, the intake control means M6 is provided with a throttle valve provided midway in the intake passage of the internal combustion engine M1. Of the exhaust gas recirculation valve provided in the middle of the exhaust gas recirculation passage communicating the intake passage and the exhaust passage downstream of the throttle valve, and the vortex flow of the air-fuel mixture introduced into the cylinder. The gist is that it is configured by means for controlling at least one of the openings of the vortex flow control valve.

Further, in the invention according to claim 3, in the combustion control device for the internal combustion engine according to claim 1 or 2,
The delay time of the switching by the switching delay means M9 is from when the combustion state is switched by the combustion control means M5 until the actual intake state becomes substantially equal to the control target value by the intake control means M6. The point is to do.

(Operation) According to the invention described in claim 1, as shown in FIG. 1, the fuel is injected into the cylinder of the internal combustion engine M1 by the fuel injection means M2, and the stratified charge combustion and the homogenization are performed in the cylinder. Burning takes place. The operating state detecting means M3 detects the operating state of the internal combustion engine M1, and based on the detection result, the required combustion state determining means M4 determines whether stratified combustion is currently requested or homogeneous combustion is requested. To be done. Then, the required combustion state determination means M4
Based on the determination result of 1., the combustion control unit M5 controls the fuel injection unit M2 to control the combustion state of the internal combustion engine M1 to be switched to stratified combustion or homogeneous combustion.

Further, the intake control means M6 controls the intake air introduced into the internal combustion engine M1 based on the detection result of the operating state detection means M3. Further, the operating state detecting means M3
The fuel injection control unit M7 controls the fuel injection from the fuel injection unit M2 based on the detection result of 1. In addition, the ignition control means M8 controls the ignition of the internal combustion engine M1 based on the detection result of the operating state detection means M3.

In the present invention, the combustion control means M
When the combustion state is switched by 5, the intake control means M
Compared with the switching of control contents by 6, the fuel injection control means M
The switching between the control content by 7 and the control content by the ignition control means M8 is delayed and executed by the switching delay means M9. Therefore, even if the combustion state is switched by the combustion control means M5, after the intake state suitable for the switched combustion state (homogeneous combustion or stratified combustion) is reached,
The control content by the fuel injection control means M7 and the control content by the ignition control means M8 are switched. Therefore, it is possible to avoid a situation in which the intake state cannot immediately follow each combustion switching.

According to the invention described in claim 2, in addition to the operation of the invention described in claim 1, intake control means M6 is provided.
Is the opening degree of the throttle valve provided in the middle of the intake passage of the internal combustion engine M1, and the opening degree of the exhaust gas recirculation valve provided in the middle of the exhaust gas recirculation passage that connects the intake passage and the exhaust passage downstream of the throttle valve. , And means for controlling at least one of the openings of the vortex flow control valve for controlling the vortex flow of the air-fuel mixture introduced into the cylinder.

Further, in the invention described in claim 3, in addition to the operation of the invention described in claim 1 or 2, the combustion delay is switched by the combustion control means M5 in the delay time of the switching by the switching delay means M9. After that, the actual intake state becomes substantially equal to the control target value by the intake control means M6. Therefore, after the combustion state is switched by the combustion control unit M5 and after the intake state is almost suitable for the switched combustion state (homogeneous combustion or stratified combustion), the control contents by the fuel injection control unit M7 and The control contents are switched by the ignition control means M8.
Therefore, the above operation can be made more reliable.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment of a fuel injection control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a fuel injection control device for a direct injection engine mounted on a vehicle in the present embodiment. The engine 1 as an internal combustion engine includes, for example, four cylinders 1a, and the combustion chamber structure of each of the cylinders 1a is shown in FIG. As shown in these figures,
The engine 1 has a piston in a cylinder block 2, and the piston reciprocates in the cylinder block 2. A cylinder head 4 is provided above the cylinder block 2.
Is provided, and a combustion chamber 5 is formed between the piston and the cylinder head 4. Further, in the present embodiment, four valves are arranged per cylinder 1a, and in the figure, the first intake valve 6a, the second intake valve 6b, the first intake port 7a, and the first intake port 7b in the figure. Two intake ports, a pair of exhaust valves as 8, and a pair of exhaust ports as 9 are shown.

As shown in FIG. 3, the first intake port 7a
Is composed of a helical intake port, and the second intake port 7
b consists of a straight port that extends almost straight.
In addition, an ignition plug 10 is disposed at the center of the inner wall surface of the cylinder head 4. Further, a fuel injection valve 11 is arranged near the inner wall surface of the cylinder head 4 near the first intake valve 6a and the second intake valve 6b. That is, in the present embodiment, the fuel from the fuel injection valve 11 is directly injected into the cylinder 1a. An ignition signal distributed by a distributor (not shown) is applied to the spark plug 10. The distributor synchronizes the high voltage output from the igniter 12 with the crank angle of the engine 1 and each spark plug 10
The ignition timing of each spark plug 10 is determined by the high voltage output timing from the igniter 12.

As shown in FIG. 2, the first intake port 7a and the second intake port 7b of each cylinder 1a are respectively connected via a first intake path 15a and a second intake path 15b formed in each intake manifold 15. Connected to the surge tank 16. A swirl control valve 17 as a swirl control valve is arranged in each second intake passage 15b. These swirl control valves 17 are connected to, for example, a step motor 19 via a common shaft 18. The step motor 19 is controlled based on an output signal from an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later.

The surge tank 16 is connected to an air cleaner 21 via an intake duct 20, and a throttle valve 23 opened and closed by a step motor 22 is arranged in the intake duct 20. That is, the throttle valve 23 of the present embodiment is a so-called electronically controlled type, and the opening / closing is controlled by driving the step motor 22 based on the output signal from the ECU 30.

By opening and closing the throttle valve 23, the amount of intake air that passes through the intake duct 20 and is introduced into the combustion chamber 5 is adjusted. In the present embodiment, the intake duct 20, the surge tank 16 and the first
An intake passage is formed by the intake passage 15a, the second intake passage 15b, and the like. A throttle sensor 25 for detecting the opening (throttle opening TA) is provided near the throttle valve 23. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder. Then, the exhaust gas after combustion is discharged to an exhaust duct (not shown) (the exhaust passage is constituted by these) via the exhaust manifold 14.

Further, in the present embodiment, a known exhaust gas circulation (EGR) device 51 is provided. This EG
The R device 51 includes an EGR passage 5 as an exhaust gas circulation passage.
2 and an EGR valve 53 as an exhaust gas circulation valve provided midway in the passage 52. EGR passage 5
2 is an intake duct 20 on the downstream side of the throttle valve 23,
It is provided so as to communicate with the exhaust duct. The EGR valve 53 has a built-in valve seat, valve body, and step motor (all not shown). The opening degree of the EGR valve 53 fluctuates when the stepping motor intermittently displaces the valve body with respect to the valve seat. And EG
When the R valve 53 opens, a part of the exhaust gas discharged to the exhaust duct flows to the EGR passage 52. The exhaust gas flows into the intake duct 20 via the EGR valve 53. That is, a part of the exhaust gas is recirculated into the intake air-fuel mixture by the EGR device 51. At this time, the recirculation amount of the exhaust gas is adjusted by adjusting the opening degree of the EGR valve 53.

By the way, the above-mentioned ECU 30 is composed of a digital computer, and is composed of a RAM (random access memory) 32, a ROM (read only memory) 33, and a microprocessor which are mutually connected via a bidirectional bus 31. It has a CPU (central processing unit) 34, an input port 35 and an output port 36. In the present embodiment, the ECU 30 constitutes required combustion state determination means, combustion control means, intake control means, fuel injection control means, ignition control means, and switching delay means.

An accelerator sensor 26, which generates an output voltage proportional to the amount of depression of the accelerator pedal 24, is connected to the accelerator pedal 24, and the accelerator sensor 26 detects the accelerator opening ACCP. The output voltage of the accelerator sensor 26 is input to the input port 35 via the AD converter 37.

The top dead center sensor 27 generates an output pulse when the first cylinder 1a reaches the intake top dead center, for example.
This output pulse is input to the input port 35. The crank angle sensor 28 has a crankshaft of 30 ° CA, for example.
An output pulse is generated each time the motor rotates, and the output pulse is input to the input port. In the CPU 34, the top dead center sensor 2
The engine speed NE is calculated (read) from the output pulse of 7 and the output pulse of the crank angle sensor 28.

Further, the rotation angle of the shaft 18 is detected by a swirl control valve sensor 29,
Thereby, the opening of the swirl control valve 17 is measured. The output of the swirl control valve sensor 29 is passed through the A / D converter 39 to the input port 35.
Connected to.

At the same time, the throttle opening 25 is detected by the throttle sensor 25. The output of the throttle sensor 25 is connected to the input port 35 via the A / D converter 40.

In the present embodiment, these throttle sensor 25, accelerator sensor 26, top dead center sensor 27,
The crank angle sensor 28, the swirl control valve sensor 29, and the like make up an operating state detecting means.

On the other hand, the output port 36 is connected to each fuel injection valve 11 and each step motor 1 via the corresponding drive circuit 38.
9, 22, the igniter 12 and the EGR valve 53 (step motor). Then, the ECU 30 detects the ROM 33 based on the signals from the sensors 25 to 29.
According to the control program stored in the fuel injection valve 1
1, step motors 19, 22, igniter 12 and E
The GR valve 53 and the like are preferably controlled.

Next, a program relating to various controls according to the present embodiment in the engine combustion control device having the above-mentioned configuration will be described with reference to a flowchart. FIG. 4 is a flow chart showing an "injection / ignition delay control routine" when switching the combustion state by controlling the injector 11 or the like in the present embodiment, which is executed, for example, by interruption every predetermined crank angle.

When the processing shifts to this routine, the ECU
First, in step 101, the various sensors 2
From 5 to 29, etc., engine speed NE, accelerator opening AC
Read various signals such as CP.

Next, at step 102, the basic injection amount Qinj is calculated based on various signals such as the engine speed NE, the accelerator opening ACCP, etc. which have been read this time.
A map or the like (not shown) is taken into consideration in this calculation.

Subsequently, in step 103, the combustion state identification area MODE _i is determined based on the engine speed NE read this time and the basic injection amount Qinj calculated this time, that is, based on the currently requested operation state. To do. Here, the combustion state identification area MODE _i is an area for determining whether stratified charge combustion or homogeneous combustion should be performed at present, for example, MODE _i =
It is determined as "0 (stratified combustion)" or "1 (homogeneous combustion)". By setting the combustion state identification area MODE _i , the above-described intake system actuators (step motors 19, 22 and EGR valve 53) are appropriately driven and controlled according to the respective areas.

Further, in step 104, it is determined whether or not the combustion state identification area MODE _i determined this time is equal to the combustion state identification area MODE _{i-1 in} the previous routine (corresponding to the cylinder 1a one before). to decide. And
If the current combustion state identification area MODE _i is not equal to the previous combustion state identification area MODE _i-1, it is determined that the requested combustion state has been switched, and step 10
Move to 5.

In step 105, it is judged whether or not the combustion state has been switched this time, but it has been switched from stratified combustion to homogeneous combustion. And, in the case of switching from stratified combustion to homogeneous combustion,
In step 106, the delay counter CDELA
Y is set to a predetermined value C0, and step 10
Move to 7. On the other hand, when it is not the one in which the stratified charge combustion is switched to the homogeneous burn, that is, the one in which the homogeneous burn is switched to the stratified charge combustion, in step 108, the delay counter CDELAY is set to a predetermined value C1. , Go to step 107.

Then, in step 107, the injection / ignition identification area FMODEI _{i is set} to the previous identification area F.
The setting is the same as MODEI _i-1, and the control thereafter is temporarily terminated. That is, even if the combustion state identification area MODE _i is switched from stratified combustion to homogeneous combustion, the identification area FMODEI _i for injection / ignition cannot be immediately switched.

If the present combustion state identification area MODE _i is equal to the previous combustion state identification area MODE _{i-1 in} step 104, the process proceeds to step 109.

Then, in step 109, it is judged whether or not the current delay counter CDELAY is larger than "0". This delay counter CDELAY
Is counted down every predetermined time (for example, every "4 ms"). Here, this countdown will be described in more detail with reference to the flowchart of FIG. The “countdown routine” is, for example, “4
It is executed by a periodic interrupt every "ms". When the processing shifts to this routine, in step 201, the ECU 3
For 0, first, the current delay counter CDELAY is read. Next, in step 202, it is judged whether or not the delay counter CDELAY of this time is "0". Then, when the delay counter CDELAY of this time is "0", the subsequent processing is temporarily ended without performing the countdown. On the other hand, this delay counter CDE
If LAY is not "0", in step 203, the value obtained by subtracting "1" from the delay counter CDELAY up to that point is added to the new delay counter CDE.
It is set as LAY (countdown), and the subsequent processing is once ended.

If the delay counter CDELAY to be counted down is judged to be larger than "0" in step 109, the routine proceeds to step 107, where the injection / ignition is performed as described above. Of the identification area FMODEI _i of the previous identification area FMODEI _i
It is assumed to be the same as _i-1, and the control thereafter is terminated once. That is, as long as the delay counter CDELAY is larger than “0”, the same identification area FMODEI _i as the previous identification area FMODEI _i-1 is adopted for the injection / ignition identification area FMODEI _i .

On the other hand, if it is determined in step 109 that the delay counter CDELAY is not greater than "0", that is, "0", step 110
Move to. Then, in step 110, the discrimination region FMODEi _i for injection / ignition is switched to match the combustion state discrimination region MODE _i for this time. And
Thereafter, the processing is temporarily terminated.

As described above, in the "injection / ignition delay control routine", even if the combustion state identification area MODE _i determined according to the operating state at that time is switched, as long as the predetermined delay time has not elapsed. is without identification area FMODEI _i for injection and ignition is switched, when the delay time has elapsed, the first time in accordance with the combustion state identification area MODE _i, is switched identification area FMODEI _i for injection and ignition Of. As a result, the injection control and the ignition control are switched according to the respective combustion states with some delay after the combustion state identification area MODE _i is switched.

As described above, according to the present embodiment, when the combustion state identification area MODE _i is switched,
The intake system actuators (step motors 19, 22 and EGR valve 53) are also appropriately driven and controlled in accordance with this switching. That is, for example, when switching from stratified combustion to homogeneous combustion, the control that matches the homogeneous combustion is
Opening of step valve 23, swirl control valve 1
7 and the opening degree of the EGR valve 53 are immediately executed. In contrast, fuel injection control and ignition (timing)
The switching of the control content of the control is executed with some delay from the switching of the control content of the intake system (switch delay means).

Then, after the intake state suitable for the switched combustion state (homogeneous combustion or stratified combustion) is reached, the control content of fuel injection and the control content of ignition are switched. Therefore, it is possible to avoid a situation in which the intake state cannot immediately follow each combustion switching. As a result, it is possible to prevent the occurrence of misfire due to the fact that the intake state cannot immediately follow the switching of the combustion state.

(Second Embodiment) Next, a second embodiment of the present invention will be described. However, since the configuration and the like of this embodiment are the same as those of the above-described first embodiment, the same members and the like are denoted by the same reference numerals and description thereof is omitted. And, below, the first
The following description focuses on differences from the first embodiment.

In other words, in the present embodiment, unlike the first embodiment in which the injection / ignition identification area FMODEI _i is delayed by a predetermined time when switching, the delay time is not predetermined. Instead, it is actually variable according to the opening degree of the swirl control valve 17. The details of the control will be described below.

FIG. 6 shows the ECU 3 in the present embodiment.
It is a flow chart which shows an "injection / ignition delay control routine" executed by 0, for example, is executed by interruption for every predetermined crank angle.

When the processing shifts to this routine, the ECU
First, in step 301, various sensors 2
From 5 to 29, etc., engine speed NE, accelerator opening AC
Various signals such as CP and swirl control valve opening SCVNOW are read. Next, at step 302, the basic injection amount Qinj is calculated based on various signals such as the engine speed NE and the accelerator opening ACCP that have been read this time, as in the first embodiment. Then, in step 303, the engine speed N read this time is read.
Based on E and the basic injection amount Qinj calculated this time, that is, based on the currently requested operation state, the combustion state identification area MODE _i is determined.

Further, in step 304, it is determined whether or not the combustion state identification area MODE _i determined this time is equal to the combustion state identification area MODE _{i-1 in} the previous routine (corresponding to the cylinder 1a one before). to decide. And
If the current combustion state identification area MODE _i is not equal to the previous combustion state identification area MODE _i-1, it is determined that the requested combustion state has been switched, and step 30
Move to 5.

In step 305, S is taken for the time being.
The CV out-of-range flag XSCVCH is set to "1". Here, the SCV out-of-range flag XSCVCH means that the actual opening of the swirl control valve 17 (swirl control valve opening SCVNOW) is the target opening S.
The value is set to "0" when the value is equal to or almost close to CVREQ, and is set to "1" when the value is largely deviated. In this step, since the requested combustion state has just been switched,
Since it is estimated that there is a relatively large gap between the swirl control valve opening SCVNOW and the target opening SCVREQ, the SCV out-of-range flag XSCV
CH is set to "1".

Then, in the following step 306,
Similar to the first embodiment (step 107), the identification area FMODEi _i for injection / ignition is set to the previous identification area F.
The setting is the same as MODEI _i-1, and the control thereafter is temporarily terminated. That is, even if the combustion state identification area MODE _i is switched from stratified combustion to homogeneous combustion, the identification area FMODEI _i for injection / ignition cannot be immediately switched.

If the current combustion state identification area MODE _i is equal to the previous combustion state identification area MODE _{i-1 in} step 304, the process proceeds to step 307.

At this step 307, the current S
It is determined whether the CV out-of-range flag XSCVCH is "1". Then, the current SCV out-of-range flag XSCV
If CH is "1", it is determined that there is still a relatively large gap between the swirl control valve opening SCVNOW and the target opening SCVREQ, and the process of step 306 is executed, and thereafter, The process of is once ended. On the other hand, the current SCV out-of-range flag XSCVC
When H is not "1", that is, when it is "0", it is determined that the swirl control valve opening SCVNOW becomes equal to or close to the target opening SCVREQ, and the routine proceeds to step 308. .

Then, in step 308, the discrimination region FMODEi _i for injection / ignition is switched to match the combustion state discrimination region MODE _i for this time. And
Thereafter, the processing is temporarily terminated.

As described above, in the "injection / ignition delay control routine" in the present embodiment, the combustion state identification area MODE determined according to the operating state at that time is provided.
_{Even if i} is switched, SCV out-of-range flag XSC
Unless the VCH is "0", that is, the swirl control valve opening SCVNOW becomes equal to or close to the target opening SCVREQ, the discrimination region FMODEI _i for injection / ignition is not switched.
Then, when the flag XSCVCH becomes "0", the combustion state identification area MODE _i is adjusted for the first time,
The identification area FMODEI _i for injection / ignition is switched. As a result, the injection control and the ignition control are switched according to the respective combustion states with some delay after the combustion state identification area MODE _i is switched.

The setting of the SCV out-of-range flag XSCVCH from "1" to "0" is set as follows. That is, FIG. 7 is a "flag setting routine" for setting the SCV out-of-range flag XSCVCH, which is executed by the ECU 30, and is executed by a regular interrupt every predetermined time (for example, "4 ms"). When the processing shifts to this routine, the ECU 30 firstly proceeds to step 401, at which the swirl control valve opening SC
VNOW and the target opening SC calculated by a separate routine
Read VREQ and VREQ respectively.

Next, at step 402, it is judged if the difference (absolute value) between the target opening SCVREQ and the swirl control valve opening SCVNOW is less than a predetermined opening C3. And the target opening SC
VREQ and swirl control valve opening SCVN
If the difference from the OW is less than or equal to the predetermined opening C3, the SCV out-of-range flag XSCVCH is set to "0" in step 403, and the subsequent processing is temporarily terminated. On the other hand, when the difference between the target opening degree SCVREQ and the swirl control valve opening degree SCVNOW is larger than the predetermined opening degree C3, the subsequent processing is temporarily terminated without performing any processing. Therefore, the SCV out-of-range flag XSC
When the VCH is set to "1", the flag XSCVCH is kept at "1" as it is.

As described above, in the present embodiment,
The combustion state identification area MODE_iIs switched
However, the SCV out-of-range flag XSCVCH is "0",
Wow, swirl control valve opening SCVNOW
Becomes equal to or close to the target opening SCVREQ.
Identification area FMOD for injection / ignition unless otherwise
EI_iIs not switched, and the flag XSCVCH is set to "0".
If it becomes, the combustion state identification area MODE is not displayed for the first time._iTo
In addition, the identification area FMODEI for injection and ignition _iCut off
Can be replaced. Therefore, it is the same as the first embodiment described above.
, Combustion state identification area MODE_iAfter switching
After the fixed time has passed (SCV out-of-range flag XSCVCH
After "0"), injection control and ignition control are
It will be switched according to the combustion state of.

Therefore, also in this embodiment, the same operational effect as that of the first embodiment can be obtained. Further, in the present embodiment, the delay time is not set to a fixed value, but the swirl control valve opening SCV
The injection control and the ignition control are adjusted to the previous combustion state until NOW becomes equal to or close to the target opening SCVREQ. Therefore, in addition to the above-described function and effect, after the combustion state is switched, it is ensured that the intake state is almost suitable for the switched combustion state (homogeneous combustion or stratified combustion). The control contents are switched. As a result, it is possible to further ensure the above-mentioned effect of preventing misfire.

Further, the control in this embodiment is particularly effective when the swirl control valve 17 does not operate very fast or when the swirl strength cannot be changed individually for each cylinder 1a. Becomes

The present invention is not limited to the above-mentioned respective embodiments, and a part of the constitution can be appropriately modified within the scope not departing from the gist of the invention and can be carried out as follows. (1) In each of the above embodiments, the combustion state identification area MOD
Although the opening control of the throttle valve 23, the swirl control valve 17, and the EGR valve 53 is switched simultaneously with the switching of E _i , they may be switched with a time difference. For example, when the swirl state can be rapidly changed, the opening control of the throttle valve 23 and the EGR mechanism valve 53 is switched first, and then the opening control of the swirl control valve 17 is changed to the intake valve 6a, 6b may be switched in accordance with the timing of opening.

(2) In the first embodiment, the delay counter CDELAY is set to a predetermined value C0,
When setting to C1, these values C0 and C1 are fixed values, but may be made variable based on a map or the like according to the engine speed NE, for example.

(3) In the above embodiment, the present invention is embodied in the in-cylinder injection type engine 1. However, any type of internal combustion engine of so-called stratified charge combustion or weakly stratified charge combustion can be used. It may be embodied in a thing. For example, a type in which the fuel is injected toward the back side of the head of the intake valves 6a and 6b of the intake ports 7a and 7b is also included. Although a fuel injection valve is provided on the intake valves 6a and 6b side, a type in which fuel is injected directly into the cylinder bore (combustion chamber 5) is also included.

(4) Further, in the above-mentioned embodiment, the structure is provided with the intake port on the helical side so that the so-called swirl can be generated, but it is not always necessary to generate the swirl. Therefore, for example, the swirl control valve 17, the step motor 19, and the like in the above embodiment can be omitted.

Similarly, the throttle valve 23 may be mechanically linked to the accelerator pedal 24, or the EGR device 53 may be omitted. However, it is necessary to have at least one control target of the intake system.

[0068]

As described in detail above, according to the present invention,
In an internal combustion engine capable of switching control between stratified combustion and homogeneous combustion, there is an excellent effect that misfire can be prevented when switching combustion states.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram showing a combustion control device for an engine according to the first embodiment.

FIG. 3 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 4 is a flowchart showing an “injection / ignition delay control routine” executed by the ECU.

FIG. 5 is a flowchart showing a “countdown routine” executed by the ECU.

FIG. 6 is a flowchart showing an “injection / ignition delay control routine” executed by an ECU in the second embodiment.

FIG. 7 is a flowchart showing a “flag setting routine” executed by the ECU in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as internal combustion engine, 11 Fuel injection valve as fuel injection means, 10 ... Spark plug, 17 ... Swirl control valve as swirl control valve, 23 ... Throttle valve, 25 ... Throttle sensor constituting operating state detecting means , 26 ... Accelerator sensor constituting driving state detecting means, 27 ... Top dead center sensor constituting driving state detecting means,
28 ... Crank angle sensor constituting operating state detecting means,
29 ... Swirl control valve sensor which constitutes operating state detecting means, 30 ... ECU which constitutes required combustion state judging means, combustion control means, intake control means, fuel injection control means, ignition control means and switching delay means, 52 ... Exhaust gas EGR passage as gas recirculation passage, 53 ... EGR valve as exhaust gas recirculation valve.

Claims (3)

[Claims] 1. A fuel injection means for injecting fuel into a cylinder of an internal combustion engine for performing stratified combustion and homogeneous combustion; an operating state detecting means for detecting an operating state of the internal combustion engine; and an operating state detecting means. Based on the detection result, a required combustion state determination means for determining whether stratified combustion or homogeneous combustion is currently required, and the fuel injection means is controlled based on the determination result of the required combustion state determination means. Then, combustion control means for switching the combustion state of the internal combustion engine to stratified combustion or homogeneous combustion control, and intake control means for controlling the intake air introduced into the internal combustion engine based on the detection result of the operating state detection means. A fuel injection control unit that controls fuel injection from the fuel injection unit based on a detection result of the operating state detection unit; A combustion control device for an internal combustion engine, comprising: an ignition control means for controlling ignition of the internal combustion engine, wherein when the combustion state is switched by the combustion control means, compared to switching of control contents by the intake control means hand,
A combustion control device for an internal combustion engine, comprising: a switching delay means for delaying and executing switching between control content by the fuel injection control means and control content by the ignition control means. 2. The intake control means comprises: an opening of a throttle valve provided in the intake passage of the internal combustion engine; and an exhaust gas recirculation passage communicating between the intake passage and the exhaust passage downstream of the throttle valve. It is constituted by means for controlling at least one of the opening degree of the exhaust gas recirculation valve provided and the opening degree of the vortex flow control valve for controlling the vortex flow of the air-fuel mixture introduced into the cylinder. A combustion control device for an internal combustion engine according to claim 1. 3. The delay time of switching by the switching delay means is substantially equal to an actual intake state with respect to a control target value by the intake control means after the combustion state is switched by the combustion control means. The combustion control device for an internal combustion engine according to claim 1 or 2, wherein