JPH09324675A - Combustion control device for internal combustion engine - Google Patents

Abstract

(57) Abstract: Stable combustion can be obtained in both stratified combustion and homogeneous combustion, and particularly suitable combustion is secured even during a transient operation state. A fuel injection valve (11) is disposed around an inner wall surface of a cylinder head (4) near a first intake valve (6a) and a second intake valve (6b) of an engine (1), and fuel from the fuel injection valve (11) is directly supplied to a cylinder. It is injected into 1a. Electronic control unit (EC
U) 30 sets the target fuel injection time, the target fuel injection timing, and the target ignition timing at predetermined set timings in advance during stratified combustion, and based on these respective data, injection amount control, injection timing control, and ignition. Perform timing control. At the time of homogeneous combustion, the latest fuel injection amount calculated in the "main routine" is adopted. Therefore, during a transition such as acceleration / deceleration, the injection amount is determined based on the latest operation information, and the injection amount with respect to the intake air amount does not become too small or too large.

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 and homogeneous combustion.

[0002]

2. Description of the Related Art In a conventionally used engine, fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is supplied to a combustion chamber in advance. 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 of the throttle valve and supplying fuel directly to the combustion chamber, a combustible mixture is present near the ignition plug, and the air-fuel ratio of the portion is increased,
There is known a so-called "stratified combustion" technique for improving ignitability.

For example, in the technique disclosed in Japanese Patent Laid-Open No. 6-123245, stratified charge combustion is performed by injecting fuel directly into the combustion chamber (cylinder injection type). Further, in this technique, when performing stratified combustion, the time from the end of fuel injection to ignition is
In the case of performing homogeneous combustion, the fuel injection start timing is set based on each map. Thus, the fuel injection timings of the plurality of cylinders are corrected so that at least the rising voltage application time does not overlap, and the voltage drop in the injector of each cylinder is suppressed.

[0005]

However, in the above prior art, the injection start timing and the like are set with respect to the injection amount calculated according to the load, but there is no indication of the timing of calculating the injection amount. There isn't. When performing stratified charge combustion, how to optimize the injection timing, injection amount, and ignition timing is an important issue.In such cases, injection is generally performed at a predetermined timing in advance. The start timing, the injection amount and the ignition timing are set as a set.

However, even when the combustion state shifts from stratified charge combustion to homogeneous charge combustion, if the injection amount is set in the same manner as described above, the following problems may occur. For example, assuming acceleration during which the accelerator pedal is suddenly depressed, in the above technique, the previous injection amount and the like can be determined based on the intake air amount information when the accelerator pedal opening is relatively small. . Therefore, there is a risk that the fuel injection amount with respect to the intake air amount becomes small (lean) at the timing when the actual injection is performed. Further, at the time of deceleration, contrary to the above, the fuel injection amount with respect to the intake air amount may be large (rich). As described above, when the injection amount calculation timing in the stratified combustion is adopted, the air-fuel ratio (in the homogeneous combustion) becomes too lean or rich, and the combustion may become unstable.

On the other hand, it is possible to calculate the fuel injection amount immediately before the start of injection. However, in this case, in the homogeneous combustion, a suitable injection amount can be obtained,
The calculation timing is too late for the stratified charge combustion, and the injection start timing, the injection amount, and the ignition timing cannot be suitable, and it is very difficult to actually adopt such a measure.

The present invention has been made in view of the above circumstances, and an object thereof is a combustion control device for an internal combustion engine capable of performing stratified combustion and homogeneous combustion, and stable combustion in both stratified combustion and homogeneous combustion. Therefore, it is an object of the present invention to provide a combustion control device for an internal combustion engine, which can ensure appropriate combustion even when the operating condition is transient.

[0009]

In order to achieve the above object, in the invention described in claim 1, as shown in FIG. 1, a fuel injection means M2 for injecting fuel into a cylinder of an internal combustion engine M1 is provided. The operating state detecting means M3 for detecting the operating state of the internal combustion engine M1 and the detection result of the operating state detecting means M3 are used to determine whether the combustion state of the internal combustion engine M1 is stratified combustion or homogeneous combustion. A combustion control device for an internal combustion engine, which comprises at least a combustion control means M4 for controlling the fuel injection means M2 to execute stratified combustion or homogeneous combustion according to the result of the determination. When the determined combustion state is stratified combustion, the fuel injection amount is set at a predetermined timing based on the detection result of the operating state detection means M3, and the fuel injection control is executed based on the fuel injection amount. When the combustion state determined by the stratification injection control means M5 and the combustion control means M4 is homogeneous combustion, the fuel is determined based on the detection result of the operating state detection means M3 immediately before the fuel injection is started. The gist is that the injection amount is reset and the homogenized injection control means M6 for executing the fuel injection control based on the latest fuel injection amount is provided.

According to the second aspect of the invention,
Similarly, as shown in FIG. 1, the fuel injection means M12 for injecting fuel into the cylinder of the internal combustion engine M11 and the internal combustion engine M1.
No. 1 operating state detecting means M13, and based on the detection results of the operating state detecting means M13, it is determined whether the combustion state of the internal combustion engine M11 is stratified combustion or homogeneous combustion, and the determination is made. A combustion control device for an internal combustion engine, comprising at least a combustion control means M14 for controlling the fuel injection means M12 to execute stratified charge combustion or homogeneous combustion according to the result, which is determined by the combustion control means M14. When the combustion state is stratified combustion, the fuel injection start timing and the fuel injection amount are set in advance at a predetermined timing based on the detection result of the operating state detection means M13, and based on the fuel injection start timing and the fuel injection amount. When the combustion state determined by the combustion control means is homogeneous combustion, and the stratification injection control means M15 that executes fuel injection control, the stratification injection control means M1. Immediately before the fuel injection start timing set in 1., the fuel injection amount is reset based on the detection result of the operating state detecting means M13, and the fuel injection control is executed based on the latest fuel injection amount. The main point is that the control means M16 is provided.

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 stratification injection control means M5, M15 further sets an ignition timing based on the detection result of the operating state detection means M3, M13 at the predetermined timing, and also controls the ignition timing based on the ignition timing. That is the gist.

(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 fuel in the cylinder is burned. As a result, the internal combustion engine M1 obtains a driving force.

Further, the operating state detecting means M3 detects the operating state of the internal combustion engine M1. Then, based on the detection result, the combustion control means M4 determines whether the combustion state of the internal combustion engine M1 is stratified combustion or homogeneous combustion, and at least the fuel injection means M2 is controlled according to the determination result. Stratified combustion or homogeneous combustion is performed.

In the present invention, when the combustion state determined by the combustion control means M4 is stratified combustion, the injection control means M5 for stratification determines the detection result of the operating state detection means M3 at a predetermined timing in advance. The fuel injection amount is set based on the fuel injection amount, and the fuel injection control is executed based on the fuel injection amount. Therefore, the calculation timing is not too late for the stratified charge combustion, and the injection amount can be suitable.

When the combustion state determined by the combustion control means M4 is a homogeneous combustion, the homogenization injection control means M6 indicates the detection result of the operating state detection means M3 immediately before the fuel injection is started. The fuel injection amount is reset based on this, and the fuel injection control is executed based on the latest fuel injection amount. Therefore, during a transition such as acceleration / deceleration, the injection amount is determined based on the latest operating state detection information. Therefore, the fuel injection amount with respect to the intake air amount does not become too small or too large at the timing when the injection is actually executed.

Further, in the invention according to claim 2,
Similarly, as shown in FIG. 1, each of the means M11 to M14 has an effect equivalent to that of the invention of claim 1. Further, when the combustion state determined by the combustion control means M14 is stratified charge combustion, the stratified charge injection control means M15 preliminarily sets the fuel injection start timing and the fuel based on the detection result of the operating state detection means M13 at a predetermined timing. The injection amount is set, and the fuel injection control is executed based on the fuel injection start timing and the fuel injection amount. Therefore, the calculation timing is not too late for the stratified charge combustion, and the fuel injection start timing and the injection amount can be suitable.

When the combustion state determined by the combustion control means is homogeneous combustion, immediately before the fuel injection start timing set by the stratification injection control means M15, by the homogenization injection control means M16, Operating state detection means M13
The fuel injection amount is reset based on the detection result of, and the fuel injection control is executed based on the latest fuel injection amount. Therefore, during a transition such as acceleration / deceleration, the injection amount is determined based on the latest operating state detection information. Therefore, the fuel injection amount with respect to the intake air amount does not become too small or too large at the timing when the injection is actually executed.

Further, in the invention described in claim 3, in addition to the operation of the invention described in claims 1 and 2, the stratified injection control means M5, M15 further cause the operating state detection means at the predetermined time. The ignition timing is also set based on the detection results of M3 and M13, and the ignition timing control is also performed based on the ignition timing. Therefore, the calculation timing is not too late for the stratified charge combustion, and the fuel injection start timing, the injection amount, and the ignition timing can be suitable.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a combustion control device for an internal combustion engine according to the present invention will be described below 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 as a fuel injection means is disposed around 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.

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 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. Instead of the step motor 19, a motor controlled according to the negative pressure of the intake ports 7a and 7b of the engine 1 may be used.

The surge tank 16 includes an intake duct 20
Is connected to the air cleaner 21 via the
Inside, a throttle valve 23 that is opened and closed by a step motor 22 that is an actuator is arranged. That is, the throttle valve 23 of the present embodiment is of a so-called electronic control type. Basically, the throttle valve 23 is controlled to open and close by the step motor 22 being driven based on the output signal from the ECU 30. Is done. The intake duct 2 is opened and closed by opening and closing the throttle valve 23.
The amount of intake air that passes through 0 and is introduced into the combustion chamber 5 is adjusted. In the present embodiment, an intake passage is constituted by the intake duct 20, the surge tank 16, the first 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. And
The exhaust gas after combustion is discharged to an exhaust duct (not shown) via the exhaust manifold 14.

Further, in this 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 to 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.

The above-described ECU 30 is composed of a digital computer, and is connected to each other via a bidirectional bus 31 RAM (random access memory) 3
2, a ROM (Read Only Memory) 33, a CPU (Central Processing Unit) 34 composed of a microprocessor, an input port 35 and an output port 36. In the present embodiment, the ECU 30 constitutes combustion control detection means, stratification injection control means, and homogenization injection control means.

An accelerator sensor 26A for generating an output voltage proportional to the amount of depression of the accelerator pedal 24 is connected to the accelerator pedal 24.
Accelerator opening ACCP is detected by 6A. The output voltage of the accelerator sensor 26A is input to the input port 35 via the AD converter 37. Similarly, the accelerator pedal 24 has a fully-closed switch 26B for detecting that the depression amount of the accelerator pedal 24 is "0".
Is provided. That is, the fully closed switch 26B
Generates a signal of "1" as the fully closed signal XL2SW when the depression amount of the accelerator pedal 24 is "0", and otherwise generates a signal of "0". The output voltage of the fully closed switch 26B is also input to the input port 35.

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 supplied to an input port 35 via an A / D converter 37.
Is input to

At the same time, the throttle sensor 25 detects the throttle opening degree TA. The output of the throttle sensor 25 is input to an input port 35 via an A / D converter 37.

In addition, in the present embodiment, an intake pressure sensor 61 for detecting the pressure in the surge tank 16 (intake pressure PiM) is provided. Further, a water temperature sensor 62 that detects the temperature of the cooling water of the engine 1 (cooling water temperature THW) is provided. The outputs of both sensors 61 and 62 are also A /
It is adapted to be input to the input port 35 via the D converter 37.

In the present embodiment, the throttle sensor 25, the accelerator sensor 26A, the fully closed switch 26
B, a top dead center sensor 27, a crank angle sensor 28, a swirl control valve sensor 29, an intake pressure sensor 61, a water temperature sensor 62, and the like constitute 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, based on signals from the sensors 25 to 29, 61, and 62, the ECU 30 operates according to a control program stored in the ROM 33,
The fuel injection valve 11, the step motors 19 and 22, the igniter 12, the EGR valve 53 and the like are suitably 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. First, FIG. 4 is a "main routine" for calculating various data in the combustion control according to the present embodiment.
It is a flowchart which shows.

When the processing shifts to this routine, the ECU
First, in step 101, various signals such as the accelerator opening ACCP and the engine speed NE are read from various sensors 25 to 29, 61 and 62.

Next, at step 102, the combustion mode FMODE at the present time is determined based on the accelerator opening ACCP and the engine speed NE which have been read this time. Here, the combustion mode FMODE determines whether to perform stratified combustion or homogeneous combustion. For example, when the load is not high or the rotation speed is not high, the combustion mode FMODE is "0" to perform stratified charge combustion.
If not, the combustion mode FMODE is set to "1" to perform homogeneous combustion.

Next, at step 103, it is judged if the currently set combustion mode FMODE is "0". If the combustion mode FMODE is "0", step 104 is performed to perform stratified charge combustion.
In, the fuel injection amount QINJ is calculated based on the engine speed NE and the accelerator opening ACCP that have been read this time. A map (not shown) is taken into consideration when calculating the fuel injection amount QINJ.

On the other hand, when the combustion mode FMODE is "1", in step 105, to perform homogeneous combustion,
The fuel injection amount QINJ is calculated based on the engine speed NE and the intake pressure PiM read this time. Here, the reason why it is based on the intake pressure PiM is that information on the intake air amount can be obtained from the intake pressure PiM and the accuracy can be further improved. A map (not shown) is taken into consideration when calculating the fuel injection amount QINJ.

After step 104 or step 105, in step 106, the fuel injection time TAU (corresponding to the injection amount) is calculated based on the fuel injection amount QINJ calculated this time.

Further, in the following step 107, the fuel injection timing AINJ and the ignition timing SA are calculated based on the engine speed NE, the fuel injection amount QINJ and the combustion mode FMODE of this time.

Further, in step 108, the ECU 30 sets the set timing Tn (n corresponds to the cylinder number) based on the fuel injection timing AINJ calculated this time.
Set. The set timing Tn is a timing adopted in a "rotation signal interrupt routine" described later. Then, the ECU 30 once ends the subsequent processing.

As described above, in the "main routine", the fuel injection amount QINJ (fuel injection time TAU) and the fuel injection timing AIN are determined according to the operating state at that time.
J and the ignition timing SA are calculated, and the set timing Tn is set.

Next, the contents of the processing for setting these data as a set based on the fuel injection amount QINJ (fuel injection time TAU), the fuel injection timing AINJ and the ignition timing SA will be described. That is, FIG. 5 is a flowchart showing a "rotation signal interruption routine" for controlling the injector 11 and the like in the present embodiment to execute fuel injection control and the like, and is executed by interruption at every predetermined number of revolutions, for example. It

When the processing shifts to this routine, the ECU
First, 30 reads various data and the like such as the fuel injection time TAU calculated in the "main routine". Then, in step 202, it is determined whether or not the current crank angle CCRANK by the crank angle sensor 28 is equal to the set timing Tn (corresponding to the predetermined time referred to in the present invention) set in the above "main routine", that is, the cylinder. It is determined whether or not the timing for setting the target fuel injection time TAUn or the like for each set has arrived. Then, when the current crank angle CCRANK is equal to the set timing Tn, in step 203, the fuel injection time TAU, the fuel injection timing AINJ, and the ignition timing SA calculated in the "main routine" are set as targets for the cylinder. Fuel injection time TAUn, target fuel injection timing A
INJn and target ignition timing SAn are set respectively.

Further, in the following step 204,
Based on the target fuel injection timing AINJn and the target ignition timing SAn set this time, the times (injection start reservation timing and ignition reservation timing) corresponding to these timings are calculated, and the routine proceeds to step 205.

On the other hand, if the present crank angle CCRANK is not equal to the set timing Tn in step 202, the process proceeds to step 205 without newly setting the target fuel injection time TAUn and the like.

In step 205, which is a transition from step 202 or step 204, it is determined whether or not the current injection start reservation timing is reached. If the current injection start reservation timing is currently set, the injection compare register (register for setting the control ON / OFF time) is set in step 206, and at the same time, the injection output port YINJn is set to ON, and step 206 20
Move to 7. If the current injection start reservation timing is not reached, step 2 is performed without performing any processing.
Move to 07.

Further, in step 207, it is judged whether or not the present is the ignition reservation timing. Then, if the present is the ignition reservation timing, step 2
At 08, the ignition compare register is set, and at the same time, the ignition output port YIGTn is set to ON, and the subsequent processing is temporarily terminated. If the current timing is not the ignition reservation timing, the subsequent process is temporarily terminated without performing any process.

As described above, in the "rotation signal interrupt routine", the target fuel injection time TAUn and the target fuel injection timing A in the cylinder are set at the set timing Tn.
INJn and target ignition timing SAn are set as a set. Further, the injection start reservation timing and the ignition reservation timing are calculated, and when the respective timings are reached, the injection compare register or the ignition compare register is set, and at the same time, the injection output port YINJn,
The ignition output port YIGTn is set on.

Next, the injection output port YINJn is output simultaneously with the injection compare register set, or the ignition output port YIGT is output simultaneously with the ignition compare register set.
The processing operation executed by the ECU 30 when n is set to ON will be described. That is, FIG.
It is a flow chart which shows the "injection compare interruption routine" performed by CU30, and is performed when the above-mentioned injection compare register corresponds with a timer.

When the processing shifts to this routine, the ECU
First, in step 302, the control unit 30 determines whether or not the injection latch YLINJn set by a separate routine is ON, and proceeds to step 303 only when the injection latch YLINJn is ON (injection is being executed). . On the other hand, if the injection latch YLINJn is off, the subsequent processing is temporarily terminated.

In step 303, it is determined whether or not the current combustion mode FMODE is "0". When the current combustion mode FMODE is “0”,
When it is determined that the stratified charge combustion is currently being executed, the process proceeds to step 304. In step 304, a time obtained by adding the target fuel injection time TAUn set in the "rotation signal interrupt routine" to the current time T1 is set as the injection end time FOFF.

On the other hand, the present combustion mode FMODE
If is 1, it is determined that the homogeneous combustion is currently being performed, and the process proceeds to step 305. Step 3
In 05, the time obtained by adding the fuel injection time TAU (latest fuel injection time) set in the "main routine" to the current time T1 is set as the injection end time FOFF.

Then, step 304 or step 30
5, the injection compare register is set in step 306, and at the same time the injection output port YI is set.
The NJn is set to OFF, and the ECU 30 once ends the subsequent processing.

As described above, in the "injection compare interrupt routine", the combustion mode FMO at that time is changed.
The injection end time FOFF is set according to DE, and after that setting, the injection compare register is set, and at the same time, the injection output port YINJn is set off.

FIG. 7 is a flow chart showing the "ignition compare interrupt routine" executed by the ECU 30, which is executed when the ignition compare register matches the timer.

When the processing shifts to this routine, the ECU
First, in step 402, the control unit 30 determines whether or not the ignition latch YLIGTn set by a separate routine is ON, and proceeds to step 403 only when the ignition latch YLIGTn is ON (charging). On the other hand, when the ignition latch YLIGTn is off, the subsequent processing is temporarily terminated.

In step 403, regardless of the current combustion mode FMODE, for the current time T2,
The time obtained by adding the target ignition timing SAn set in the "rotation signal interrupt routine" is set as the ignition time IOFF. In the present embodiment, when the ignition time IOFF is reached, that is, the ignition is performed at the same time as the charge is turned off.

Then, in step 404, the ignition compare register is set, and at the same time, the ignition output port YIGTn is set to OFF, and the ECU 30 once terminates the subsequent processing.

As described above, in the "ignition compare interrupt routine", the combustion mode FMO at that time is changed.
The ignition time IOFF is set regardless of DE, and after the setting, the ignition compare register is set, and at the same time, the ignition output port YIGTn is set to OFF.

Next, the operation and effect of this embodiment will be described. (A) According to the present embodiment, as shown in FIG. 8, when the combustion mode FMODE is “0”, that is, at the time of stratified combustion, the target fuel injection time TAUn and the target fuel injection timing are set at the predetermined set timing Tn. AINJn and target ignition timing SAn are set respectively. Then, the fuel injection amount control, the injection timing control, and the ignition timing control are executed based on these respective data. Here, for the stratified charge combustion, how to adjust the injection timing (including the injection amount) and the ignition timing is important, but in the present embodiment, these data are set as a set at a predetermined set timing Tn. To be done. Therefore, for the stratified combustion,
The calculation timing is not too late, and the injection amount can be suitable. Therefore, during stratified combustion,
Stable combustion can be secured.

(B) As shown in FIG. 8, when the combustion mode FMODE is "1", that is, at the time of homogeneous combustion, the latest fuel injection time TAU calculated in the "main routine" is adopted and the injection is completed. Time FOFF is set. Therefore, during a transition such as acceleration / deceleration, the injection amount is determined based on the latest operating state detection information.

For example, in the case of accelerating, as shown in FIG. 9, every time the main routine goes around, that is, at time t1,
At t2, t3 and t4, the fuel injection time TAU, the fuel injection timing AINJ and the ignition timing SA are calculated. Furthermore, a predetermined set timing Tn (for example, Tn is the time t
Target fuel injection time TA at the time between 1 and t2)
Un, target fuel injection timing AINJn and target ignition timing S
An is set respectively. Then, assuming that fuel injection is started at time t5, conventionally, at time t1
While the injection amount is determined based on the operating state at time t3, in the present embodiment, the injection amount (fuel injection time TAU) is determined based on the operating state (intake amount, etc.) at time t3 during homogeneous combustion. The injection is performed based on the calculated fuel injection time TAU (that is, the injection amount is effectively recalculated). Therefore, the actual fuel injection amount with respect to the intake air amount does not become too small at the timing when the actual injection is performed.

On the contrary, the actual fuel injection amount does not become excessive during deceleration as well. As a result, stable combustion can be ensured even during homogeneous combustion.

The present invention is not limited to the above embodiment, but may be configured as follows, for example. (1) In the above embodiment, the target ignition timing SAn set by the "rotation signal interruption routine" is adopted as the ignition timing regardless of whether the combustion is stratified combustion or homogeneous combustion, but fuel injection may be performed if necessary. As with time, during homogeneous combustion, the ignition timing S calculated in the "main routine" is calculated.
You may make it employ | adopt A.

(2) 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 the type that performs 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.

(3) Further, in the above-mentioned embodiment, the structure is provided with the helical intake port and 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.

(4) When calculating the fuel injection amount QINJ in the above embodiment, different parameters (for example, intake air amount, throttle opening, etc.) may be adopted.

[0068]

As described in detail above, according to the present invention,
In a combustion control device for an internal combustion engine capable of performing stratified charge combustion and homogeneous combustion, stable combustion can be obtained in both stratified charge combustion and homogeneous charge combustion, and is particularly suitable even during transient operation conditions such as acceleration or deceleration. It has an unprecedented excellent effect of ensuring combustion.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram showing a combustion control device for an engine in one embodiment.

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

FIG. 4 is a flowchart showing a “main routine” executed by the ECU.

FIG. 5 is a flowchart showing a “rotation signal interrupt routine” executed by the ECU.

FIG. 6 is a flowchart showing an “injection compare interrupt routine” executed by the ECU.

FIG. 7 is a flowchart showing an “ignition compare interrupt routine” executed by the ECU.

FIG. 8 is a timing chart showing the behavior of fuel injection and ignition during stratified combustion and homogeneous combustion.

FIG. 9 is a timing chart for explaining the function and effect at the time of homogeneous combustion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as internal combustion engine, 10 ... Spark plug, 1
DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve as fuel injection means, 25 ... Throttle sensor which comprises operating state detection means, 26A ... Accelerator sensor which comprises operating state detection means, 26B ... Full closing switch which constitutes operating state detection means, 27 ... Top dead center sensor constituting operating state detecting means 28 ... Crank angle sensor constituting operating state detecting means 29 ... Swirl control valve sensor constituting operating state detecting means 30
An ECU that constitutes combustion control means, stratification injection control means, and homogenization injection control means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02D 41/02 330 F02D 41/02 330F 335 335 41/34 9523-3G 41/34 E 45/00 310 45/00 310A F02P 5/15 F02P 5/15 B

Claims (3)

[Claims] 1. A fuel injection means for injecting fuel into a cylinder of an internal combustion engine, an operating state detecting means for detecting an operating state of the internal combustion engine, and an internal combustion engine of the internal combustion engine based on a detection result of the operating state detecting means. An internal combustion engine including: a combustion control unit that determines whether the combustion state is stratified combustion or homogeneous combustion, and controls at least the fuel injection unit to execute stratified combustion or homogeneous combustion according to the determination result. In the combustion control device, when the combustion state determined by the combustion control means is stratified combustion, the fuel injection amount is set in advance based on the detection result of the operating state detection means at a predetermined time, When the combustion state determined by the combustion control means is a homogeneous combustion, the stratification injection control means for executing fuel injection control based on the injection amount, and the operation just before the fuel injection is started. Combustion control of an internal combustion engine, comprising resetting the fuel injection amount based on the detection result of the state detecting means, and homogeneous injection control means for executing fuel injection control based on the latest fuel injection amount. apparatus. 2. A fuel injection means for injecting fuel into a cylinder of an internal combustion engine, an operating state detecting means for detecting an operating state of the internal combustion engine, and an operating state detecting means for detecting the operating state of the internal combustion engine based on a detection result of the operating state detecting means. An internal combustion engine including: a combustion control unit that determines whether the combustion state is stratified combustion or homogeneous combustion, and controls at least the fuel injection unit to execute stratified combustion or homogeneous combustion according to the determination result. In the combustion control device, when the combustion state determined by the combustion control means is stratified combustion, the fuel injection start timing and the fuel injection amount are preliminarily determined at a predetermined timing based on the detection result of the operating state detection means. If the combustion state determined by the combustion control means is set, and the stratification injection control means for executing fuel injection control based on the fuel injection start timing and the fuel injection amount is homogeneous combustion, Immediately before the fuel injection start timing set by the stratified layer injection control means, the fuel injection amount is reset based on the detection result of the operating state detection means, and the fuel injection control is performed based on the latest fuel injection amount. A combustion control device for an internal combustion engine, comprising: a homogenization injection control unit that executes the combustion control device. 3. The stratified injection control means further sets an ignition timing based on the detection result of the operating state detection means at the predetermined timing, and also controls the ignition timing based on the ignition timing. The combustion control device for an internal combustion engine according to claim 1 or 2, wherein: