JP2000104594A - Combustion control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion control device for an internal combustion device to prevent worsening of drivability due to a step generated at engine output torque when an accelerator opening is changed in the vicinity of '0'. SOLUTION: A fuel injection amount of an engine 11 is calculated based on a pedaling amount of an accelerator pedal 25. When a fuel injection amount calculated in this way is below a minimum fuel injection amount decided by a fuel injection valve 40, namely when an accelerator pedaling amount is a value approximately equal to '0', a minimum fuel injection amount is decided as a fuel injection amount, and fuel in an amount corresponding to the fuel injection amount is injected through the injection valve 40. Further, when the minimum fuel injection amount is set in a manner described above as a fuel injection amount, the fuel injection timing and the ignition timing of the engine are corrected to the delay angle side to reduce output torque of the engine 11, and through the correction, output torque corresponding to an accelerator pedaling amount is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, an internal combustion engine that performs "stratified combustion" capable of combustion at an air-fuel ratio leaner than the stoichiometric air-fuel ratio at a low engine load with the intention of improving fuel efficiency has been proposed and put into practical use. I have. As an internal combustion engine that performs such "stratified combustion", for example, one described in Japanese Patent Application Laid-Open No. 4-228856 is known.

[0003] In the internal combustion engine described in the publication,
Fuel injected into the combustion chamber during the compression stroke of the engine is collected around the ignition plug, and a mixture of the collected fuel and air in the combustion chamber is ignited by the ignition plug, whereby "stratified combustion" is performed. Is executed. In this "stratified combustion", the throttle valve is controlled to be open compared to the case of "homogeneous combustion" in order to increase the average air-fuel ratio of the air-fuel mixture.

[0004] In an internal combustion engine in which the above-mentioned "stratified combustion" is performed, a fuel injection amount is set based on an accelerator opening so as to obtain an engine output torque corresponding to an accelerator pedal depression amount (accelerator opening). Then, an amount of fuel corresponding to the set fuel injection amount is injected and supplied to the combustion chamber. Thus, by adjusting the fuel injection amount according to the accelerator opening, the output torque of the internal combustion engine is controlled to a value corresponding to the accelerator opening. Since the output torque required for the internal combustion engine increases as the accelerator opening increases, the fuel injection amount is set to a larger value as the accelerator opening increases, as shown by the solid lines in FIGS. 7B and 7C. Is done.

[0005]

Incidentally, fuel injection in an internal combustion engine is performed by a fuel injection valve, and the minimum value (minimum fuel injection amount) of the amount of fuel that can be injected from the fuel injection valve is determined by the fuel injection valve. You. That is, in the fuel injection valve, when the fuel injection amount is extremely small, the fuel injection state fluctuates and accurate fuel injection is not performed. However, the minimum value of the fuel injection amount where such fluctuation does not occur is the minimum fuel injection amount. It becomes the injection amount.

When the fuel injection amount set based on the accelerator opening is equal to or less than the minimum fuel injection amount, that is, when the accelerator opening is a value located in the region A of FIG. The fuel injection amount is set.
As a result, as shown in FIG. 7A, when the accelerator opening gradually increases from “0”, while the accelerator opening is located within the region A, the fuel injection amount becomes as shown in FIG. The transition will be as shown by the broken line L1.

In addition, as described above, the accelerator opening is in the region A
Instead of setting the minimum fuel injection amount as the fuel injection amount when the value is within the range, the fuel injection amount may be set to “0” to perform the fuel cut. In this case, the fuel injection amount changes as shown by a broken line L2 in FIG. 7C with the change in the accelerator opening.

As described above, when the accelerator opening is located in the region A, that is, when the accelerator opening is close to "0", the fuel injection amount is "0" or the minimum fuel injection amount regardless of the accelerator opening. Will be set to Therefore, for example, when the accelerator opening is gradually increased from “0”, the engine output torque cannot be increased smoothly by gradually increasing the fuel injection amount, and a step occurs in the engine output torque, resulting in drivability. Will get worse.

The present invention has been made in view of such circumstances, and has as its object that when the accelerator opening changes near "0", a step occurs in the engine output torque and drivability deteriorates. It is an object of the present invention to provide a combustion control device for an internal combustion engine that can prevent the occurrence of a combustion.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, the fuel injection amount of the internal combustion engine is set according to the accelerator opening, and the fuel injection amount corresponding to the set fuel injection amount is set. In a combustion control apparatus for an internal combustion engine that controls the engine output torque according to the accelerator opening by supplying an amount of fuel to the combustion chamber of the engine, a fuel injection amount set according to the accelerator opening Is less than or equal to a predetermined minimum fuel injection amount, the minimum fuel injection amount is set as the fuel injection amount, and the operation of the internal combustion engine is controlled so as to obtain an engine output torque corresponding to the accelerator opening. And a control means for controlling the predetermined control system to reduce the engine output torque.

According to this configuration, when the fuel injection amount set in accordance with the accelerator opening is equal to or less than a predetermined minimum fuel injection amount, the minimum fuel injection amount is set as the fuel injection amount. A predetermined control system for controlling the operation of the internal combustion engine so as to obtain an engine output torque corresponding to the accelerator opening is controlled to lower the engine output torque. Therefore, when the accelerator opening changes near "0", for example, when the accelerator opening gradually increases from "0", a step in the engine output torque is prevented from deteriorating drivability. Will be able to do it.

According to a second aspect of the present invention, in the first aspect of the invention, the control means controls the predetermined control system based on the accelerator opening so as to obtain an engine output torque corresponding to the accelerator opening. The control amount was corrected.

According to this configuration, when the engine output torque corresponding to the accelerator opening is obtained, the control amount of the predetermined control system for controlling the operation of the internal combustion engine is corrected based on the accelerator opening. Therefore, the engine output torque corresponding to the accelerator opening can be accurately obtained.

According to the third aspect of the present invention, the first or second aspect is provided.
In the invention described in the above, the internal combustion engine executes stratified combustion, and the control means delays a fuel injection timing and an ignition timing of the internal combustion engine so that an engine output torque corresponding to the accelerator opening is obtained. It was corrected to the corner side.

In an internal combustion engine in which stratified combustion is performed, the air-fuel ratio of the air-fuel mixture around the ignition plug must be set to a value suitable for ignition when the ignition plug is ignited. If it changes to, a misfire or the like may occur. According to this configuration, when the engine output corresponding to the accelerator opening is obtained, both the fuel injection timing and the ignition timing are corrected to the retard side to reduce the engine output torque, and the correction is performed. As a result, an engine output torque corresponding to the accelerator opening can be obtained without causing a misfire or the like.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, a negative pressure adjusting means for adjusting a negative pressure generated in an intake system of the internal combustion engine is further provided, and the control means comprises: The negative pressure adjusting means is controlled to increase the negative pressure so that an engine output torque corresponding to the accelerator opening is obtained.

According to this configuration, the engine output torque is reduced by controlling the negative pressure adjusting means to the side where the negative pressure generated in the intake system of the internal combustion engine increases, and the engine output torque corresponding to the accelerator opening is increased. Can be obtained.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the internal combustion engine has a plurality of cylinders, and the control means corresponds to the accelerator opening. The number of operating cylinders of the internal combustion engine is controlled to decrease such that the engine output torque obtained is obtained.

According to this configuration, the engine output torque is reduced by controlling the number of operating cylinders of the internal combustion engine to a reduced side, and an engine output torque corresponding to the accelerator opening can be obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an in-line four-cylinder automobile gasoline engine will be described below with reference to FIGS.

As shown in FIG. 1, a piston 12 is provided in each of the first cylinder # 1 to the fourth cylinder # 4 of the engine 11 (only the first cylinder # 1 is shown in FIG. 1). This piston 12 is a cylinder block 1 of the engine 11.
1a, the connecting rod 13 can be reciprocated.
Through a crankshaft 14 which is an output shaft of the engine 11. The reciprocating movement of the piston 12 is performed by the connecting rod 13 on the crankshaft 1.
4 rotations. The head of the piston 12 is formed with a depression 12a necessary for performing stratified combustion.

A signal rotor 14a is mounted on the crankshaft 14. This signal rotor 14
A plurality of protrusions 14b are provided at equal angles around the axis of the crankshaft 14 on the outer peripheral portion of a. A crank position sensor 14c is provided on the side of the signal rotor 14a. When the crankshaft 14 rotates and the projections 14b of the signal rotor 14a sequentially pass by the side of the crank position sensor 14c, the sensor 14c detects pulse-like detection corresponding to the passage of the projections 14b. A signal is output.

On the other hand, a cylinder head 15 is provided at the upper end of the cylinder block 11a, and a combustion chamber 16 is provided between the cylinder head 15 and the piston 12.
The combustion chamber 16 communicates with a pair of intake ports 17a and 17b provided in the cylinder head 15 and a pair of exhaust ports 18a and 18b (FIG. 1 shows one intake port 17b and one exhaust port). 18b only).
These intake and exhaust ports 17a, 17b, 18a, 1
FIG. 2 shows a plane cross-sectional shape of 8b.

As shown in FIG.
Is a helical port extending in a curved manner, and the intake port 17b is a straight port extending in a straight line. When air passes through the intake port (helical port) 17a and is sucked into the combustion chamber 16, swirl is generated in the combustion chamber 16 in the direction indicated by the dashed arrow. The intake ports 17a and 17b and the exhaust ports 18a and 18b are provided with an intake valve 19 and an exhaust valve 20, respectively.

As shown in FIG. 1, an intake camshaft 21 and an exhaust camshaft 22 for opening and closing the intake valve 19 and the exhaust valve 20 are rotatably supported on the cylinder head 15. The intake and exhaust camshafts 21 and 22 are connected to the crankshaft 1 via a timing belt and gears (both not shown).
4 and the rotation of the crankshaft 14 is transmitted by the belt and the gears. Then, when the intake camshaft 21 rotates, the intake valve 19 is driven to open and close, so that the intake ports 17a and 17b and the combustion chamber 16 are communicated and shut off. Further, when the exhaust camshaft 22 rotates, the exhaust valve 20 is driven to open and close, and the exhaust ports 18a, 18b and the combustion chamber 16 are communicated and shut off.

In the cylinder head 15, on the side of the intake camshaft 21, a cam position sensor 21b for detecting a projection 21a provided on the outer peripheral surface of the shaft 21 and outputting a detection signal is provided. When the intake camshaft 21 rotates, the protrusion 21a of the shaft 21 passes by the side of the cam position sensor 21b. In this state, the cam position sensor 21b
Thus, the detection signal is output at predetermined intervals corresponding to the passage of the protrusion 21a.

The intake ports 17a and 17b and the exhaust ports 18a and 18b have an intake pipe 30 and an exhaust pipe 3 respectively.
1 is connected. The interior of the intake pipe 30 and the interior of the intake ports 17a and 17b constitute an intake passage 32, and the interior of the exhaust pipe 31 and the interior of the exhaust ports 18a and 18b constitute an exhaust passage 33.
It has become. A throttle valve 23 is provided in an upstream portion of the intake passage 32. This throttle valve 2
3 is rotated by driving a throttle motor 24 composed of a direct current (DC) motor to adjust the opening. The opening of the throttle valve 23 is detected by a throttle position sensor 44.

The driving of the throttle motor 24 is controlled based on the opening degree (accelerator depression amount) of an accelerator pedal 25 provided in the interior of the vehicle. That is, when the driver of the vehicle depresses the accelerator pedal 25, the accelerator depression amount is detected by the accelerator position sensor 26, and the drive of the throttle motor 24 is controlled based on the detection signal of the sensor 26. By adjusting the opening of the throttle valve 23 based on the drive control of the throttle motor 24, the air flow area of the intake passage 32 changes, and the amount of air drawn into the combustion chamber 16 is adjusted.

In the intake passage 32, the throttle valve 2
A vacuum sensor 36 for detecting a pressure in the passage 32 is provided in a portion located downstream of the passage 3. Then, the vacuum sensor 36 outputs a detection signal corresponding to the detected pressure in the intake passage 32. In addition, the intake passage 3
In 2, a swirl control valve (SCV) 34 is provided at a portion that is located downstream of the vacuum sensor 36 and communicates with the intake port (straight port) 17b. SCV 34 is a swirl motor 35
The opening degree is adjusted by the drive of. And
As the opening of the SCV 34 decreases, the amount of air passing through the intake port (helical port) 17a shown in FIG. 2 increases, and the swirl generated in the combustion chamber 16 increases.

As shown in FIG. 1, the cylinder head 15 has a fuel injection valve 40 for injecting fuel into the combustion chamber 16 and a mixture of fuel and air filled in the combustion chamber 16. And an ignition plug 41 for performing ignition. The ignition timing of the air-fuel mixture by the ignition plug 41 is adjusted by an igniter 41a provided above the ignition plug 41. And the fuel injection valve 4
When fuel is injected into the combustion chamber 16 from 0, the fuel is mixed with the air drawn into the combustion chamber 16 through the intake passage 32, and a mixture of air and fuel is formed in the combustion chamber 16. Is done. Further, the air-fuel mixture in the combustion chamber 16 is ignited by the ignition plug 41 and burns, and the air-fuel mixture after the combustion is sent to the exhaust passage 33 as exhaust gas.

Next, the electrical configuration of the combustion control device for the engine 11 in this embodiment will be described with reference to FIG.
This combustion control device controls fuel injection amount, ignition timing,
An electronic control unit (hereinafter, referred to as “ECU”) 92 for controlling the operating state of the engine 11 such as throttle opening control and SCV opening control is provided. This EC
U92 is configured as a logical operation circuit including a ROM 93, a CPU 94, a RAM 95, a backup RAM 96, and the like.

The ROM 93 is a memory that stores various control programs and maps and the like that are referred to when executing the various control programs.
The arithmetic processing is executed based on various control programs and maps stored in the OM 93. The RAM 95 is a CPU
94 is a memory for temporarily storing the calculation result at 94, data input from each sensor, and the like.
Reference numeral 6 denotes a nonvolatile memory for storing data to be stored when the engine 11 is stopped. And ROM93, CP
The U 94, the RAM 95, and the backup RAM 96 are connected to each other via a bus 97, and are also connected to an external input circuit 98 and an external output circuit 99.

The external input circuit 98 is connected to the crank position sensor 14c, the cam position sensor 21b, the accelerator position sensor 26, the vacuum sensor 36, the throttle position sensor 44, and the like.
On the other hand, the external output circuit 99 includes a throttle motor 2
4. The swirl motor 35, the fuel injection valve 40, the igniter 41a and the like are connected.

The ECU 92 configured as described above determines the intake pressure PM based on the detection signal from the vacuum sensor 36, and determines the accelerator depression amount ACCP based on the detection signal from the accelerator position sensor 26. Furthermore, ECU
A step 92 obtains the engine speed NE based on the detection signal from the crank position sensor 14c. Then, the intake pressure PM and the engine speed NE obtained as described above,
Alternatively, the accelerator depression amount ACCP and the engine speed NE
And the fuel injection amount TAU with reference to a known map.
Is calculated. The fuel injection amount TA thus calculated
U increases as the engine speed NE increases, and at the same time, the intake pressure PM or the accelerator depression amount ACC.
The value increases as P increases.

The engine load of the engine 11 is represented by the fuel injection amount TAU. The ECU 92 sets the combustion method of the engine 11 to “homogeneous combustion” when the operating state of the engine 11 is in the high-speed high-load region, and sets the combustion method of the engine 11 to “homogeneous combustion” when the engine 11 is in the low-speed low load region. Stratified combustion ". Changing the combustion method in this way is performed at high rotation and high load, where high output is required, by increasing the engine output by setting the air-fuel ratio of the air-fuel mixture to a value on the rich side, and by reducing the low rotation and low load that does not require very high output. This is because the air-fuel ratio is sometimes set to a lean value to improve the fuel efficiency.

When the combustion mode of the engine 11 is set to "homogeneous combustion", the ECU 92 performs a map calculation of the fuel injection amount TAU based on the intake pressure PM obtained based on the detection signal from the vacuum sensor 36 and the engine speed NE. .
The ECU 92 controls the drive of the fuel injection valve 40 to inject fuel from the fuel injection valve 40 during the intake stroke of the engine 11 in an amount corresponding to the fuel injection amount TAU.
The air-fuel ratio of the air-fuel mixture formed in the combustion chamber 16 based on such fuel injection has a stoichiometric air-fuel ratio or a value larger than the stoichiometric air-fuel ratio. The ECU 92 further controls the throttle motor 24, the igniter 41a, and the swirl motor 3 so that the throttle opening, the ignition timing, the opening of the SCV 34, and the like are suitable for “homogeneous combustion”.
5 and the like.

When the stratified combustion is used as the combustion mode of the engine 11, the ECU 92 calculates the fuel injection amount TAU from the accelerator depression amount ACCP and the engine speed NE. The ECU 92 injects fuel during the compression stroke of the engine 11 based on the fuel injection amount TAU. The air-fuel ratio of the air-fuel mixture formed in the combustion chamber 16 by such fuel injection is set to a value leaner than the air-fuel ratio at the time of “homogeneous combustion”. The ECU 92 determines that the throttle opening, the ignition timing, the opening of the SCV 34, and the like are “stratified combustion”.
The drive of the throttle motor 24, the igniter 41a, the swirl motor 35, and the like are controlled so as to be suitable for the motor.

At the time of such “stratified combustion”, the fuel injected from the fuel injection valve 40 during the compression stroke of the engine 11 enters into the depression 12 a (FIG. 1) provided in the head of the piston 12. Further, swirl is generated based on the opening degree adjustment of the SCV 34 by drive control of the swirl motor 35, and the fuel is collected around the spark plug 41 by the swirl and the movement of the piston 12. By collecting the fuel around the ignition plug 41 in this manner, even if the average air-fuel ratio of the entire air-fuel mixture in the combustion chamber 16 is larger than that during the “homogeneous combustion”, the air-fuel ratio of the air-fuel mixture around the same plug 41 is increased. A suitable mixture is ignited to be suitable for ignition. In addition, the throttle opening is controlled to the open side to increase the average air-fuel ratio of the entire air-fuel mixture in the combustion chamber 16 compared with the time of "homogeneous combustion", and the amount of intake air is increased. 11 is reduced.

Next, an outline of the combustion control in this embodiment will be described with reference to a time chart of FIG. FIGS. 4A to 4D show the accelerator depression amount ACCP, the fuel injection amount TAU, and the fuel injection timing Ain over time.
5 shows changes in jiC and the retard amount Artd of the ignition timing ST, and changes in the output torque of the engine 11.

As shown in FIG. 4A, when the accelerator depression amount ACCP gradually increases, the accelerator depression amount A
When the CCP is close to “0”, the fuel injection amount TAU calculated based on the accelerator depression amount ACCP changes on the condition that the engine speed NE is constant, as shown by a broken line in FIG. 4B. . In this state, the calculated fuel injection amount TAU becomes smaller than the minimum fuel injection amount TAUmin.

The minimum fuel injection amount is defined as the fuel injection valve 4
The minimum value of the amount of fuel that can be injected from 0, which is determined by the fuel injection valve 40. That is, in the fuel injection valve 40, when the fuel injection amount TAU is extremely small, the fuel injection state fluctuates and accurate fuel injection is not performed.
The minimum value of AU is set as the minimum fuel injection amount TAUmin.

The fuel injection amount TAU calculated based on the accelerator depression amount ACCP is the minimum fuel injection amount TAUmin.
In the following cases, that is, when the accelerator depression amount ACCP is located within the region A in FIG. 4, the ECU 92 sets the minimum fuel injection amount TAUmin as the fuel injection amount TAU. As a result, in the region A, the fuel injection amount T
The AU transitions as shown by the solid line in FIG. When fuel is injected from the fuel injection valve 40 in an amount corresponding to the fuel injection amount TAU that changes in this manner, the accelerator depression amount ACCP
Changes around "0", such as when gradually increasing from "0", a step occurs in the output torque of the engine 11 and drivability decreases.

Therefore, in this embodiment, the accelerator depression amount A
When the CCP is in the region A, the fuel injection timing AinjiC and the ignition timing ST are retarded by the retard amount Artd obtained based on the accelerator depression amount ACCP. The retard amount Artd is a value obtained by subtracting the current accelerator depression amount ACCP from the accelerator depression amount ACCP (reference value ACCPA) when the calculated fuel injection amount TAU matches the minimum fuel injection amount TAUmin (“ACCPA−
ACCP ") and is obtained by referring to the map of FIG. The reference value ACCPA increases as the engine speed NE increases, provided that the pressure of the fuel supplied from the fuel tank side of the vehicle to the fuel injection valve 40 is constant.

As is apparent from the map of FIG. 5, the retard amount Artd increases as the value obtained by subtracting the accelerator depression amount ACCP from the reference value ACCPA increases. Therefore, when the accelerator depression amount ACCP that changes as shown in FIG. 4A is located in the area A, the retard amount Artd is increased as shown in FIG. 4C with the increase in the accelerator depression amount ACCP. Will change. That is, the retard amount Artd increases as the accelerator pedal depression amount ACCP approaches “0”, and the accelerator pedal depression amount ACCP becomes equal to the reference value ACC.
It becomes smaller as it increases toward PA.

When the fuel injection timing AinjiC and the ignition timing ST are retarded by the retard amount Artd, the output torque when the accelerator depression amount ACCP changes near "0" is reduced, and the output torque is reduced. The generation of a step is suppressed. As a result, as shown in FIG. 4D, the output torque of the engine 11 smoothly increases with an increase in the accelerator depression amount ACCP, and deterioration of drivability due to the step of the output torque is prevented.

Next, the combustion control procedure of this embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a combustion control routine for performing the above-described combustion control.
This combustion control routine is executed by the ECU 92, for example, by interruption at predetermined time intervals. Then, the fuel injection amount TAU is calculated by the combustion control routine. When the fuel injection amount TAU is calculated in this manner, the ECU 92 controls the drive of the fuel injection valve 40 by another routine to inject fuel in an amount corresponding to the fuel injection amount TAU.

In the combustion control routine, the ECU 93
Is the engine speed N as the process in step S101.
Based on E and the accelerator depression amount ACCP, a fuel injection amount TAU is calculated with reference to a known map. After that, it advances to step S102. When the calculated fuel injection amount TAU is equal to or less than the minimum fuel injection amount TAUmin, the processing of steps S102 and S103 is performed.
This is for setting Umin as the fuel injection amount TAU. The ECU 92 performs the process of step S102 as follows:
The calculated fuel injection amount TAU is the minimum fuel injection amount TA
It is determined whether it is less than Umin. Then, “TAU ≦ TAU
If it is not "min", this combustion control routine is temporarily terminated,
If “TAU ≦ TAUmin”, the following step S103
Proceed to.

The ECU 92 sets the minimum fuel injection amount TAUmin as a new fuel injection amount TAU in the process of step S103. Therefore, the accelerator depression amount AC
If the accelerator depression amount ACCP is small and the fuel injection amount TAU is extremely small when the CP gradually increases from “0”, the fuel injection amount TAU is increased with respect to the increase in the accelerator depression amount ACCP in FIG. The transition will be as shown by the solid line in b).

Subsequently, the ECU 92 executes the fuel injection timing AinjiC and the ignition timing ST in step S104.
Is calculated to be used to correct the angle to the retard side. The retard amount Artd is a value obtained by subtracting the current accelerator depression amount ACCP from the accelerator depression amount ACCP (reference value ACCPA) when the calculated fuel injection amount TAU matches the minimum fuel injection amount TAUmin (“ACCPA−
ACCP ”) and is calculated with reference to the map in FIG. Since the retard amount Artd increases as “ACCPA-ACCP” increases, the retard amount changes as shown in FIG. 4C with an increase in the accelerator depression amount ACCP.

After calculating the retard amount Artd as described above, the process proceeds to step S105. Step S105, S1
The process 06 is for correcting the fuel injection timing AinjiC and the ignition timing ST to the retard side by the retard amount Artd. The ECU 92 executes the process of step S105, in which the basic fuel injection timing AinjiC0 to the retard amount Ar
The value obtained by subtracting td is defined as the fuel injection timing AinjiC. The ECU 92 sets the ignition timing ST to a value obtained by subtracting the retard amount Artd from the basic ignition timing ST0 as the process of the subsequent step S106, and then temporarily ends the combustion control routine.

When the fuel injection timing AinjiC and the ignition timing ST are calculated in this manner, the ECU 92 controls the driving of the fuel injection valve 40 and the igniter 41a by another routine, and performs the fuel injection at a timing corresponding to the fuel injection timing AinjiC. At the same time, the ignition by the spark plug 41 is executed at a timing corresponding to the ignition timing ST. Usually, since the retard amount Artd is “0”, the basic fuel injection timing Ai is determined by the processing in steps S105 and S106.
The njiC0 and the basic ignition timing ST0 are directly used as the fuel injection timing AinjiC and the ignition timing ST.

However, when the accelerator depression amount ACCP is located within the region A of FIG. 4, the retard amount Artd is "0".
Therefore, the fuel injection timing AinjiC and the ignition timing ST are obtained by subtracting the retard amount Artd from the basic fuel injection timing AinjiC0 and the basic ignition timing ST0. Therefore, when the accelerator depression amount ACCP is located within the region A in FIG. 4, the fuel injection timing Ai is equal to the retard amount Artd.
The njiC and the ignition timing ST are corrected to the retard side.

Even if the fuel injection amount TAU changes as indicated by the solid line in FIG. 4B in the region A by such correction, the output torque of the engine 11 can be reduced by the retard amount Artd. As a result, the output torque of the engine 11 increases as shown in FIG.
As shown in (d), the output torque increases smoothly, and an output torque corresponding to the accelerator depression amount ACCP can be obtained accurately.

By the way, when the accelerator depression amount ACCP is located within the region A, the combustion system of the engine 11 is set to "stratified combustion". In this "stratified combustion", since the air-fuel ratio of the air-fuel mixture around the ignition plug 41 must be set to a value suitable for ignition at the time of ignition by the ignition plug 41, the time between the fuel injection timing AinjiC and the ignition timing ST is reduced. Excessive change may cause misfire or the like.

In this embodiment, the accelerator depression amount ACCP
Is in the region A, the fuel injection timing Ain
Both jiC and ignition timing ST are corrected to the retard side to reduce the output torque, and the fuel injection timing Ainji
There is no excessive change between C and the ignition timing ST.
Therefore, the accelerator depression amount ACCP can be obtained even in the region A without causing misfire or the like based on an excessive change between the fuel injection timing AinjiC and the ignition timing ST.
Can be obtained corresponding to the output torque of the engine 11.

According to this embodiment in which the processing described in detail above is performed, the following effects can be obtained. (1) When the fuel injection amount TAU calculated according to the accelerator depression amount ACCP is equal to or less than the minimum fuel injection amount TAUmin,
The minimum fuel injection amount TAUmin is set as the fuel injection amount TAU, and the fuel injection timing Ainji is set so that an output torque corresponding to the accelerator depression amount ACCP is obtained.
C and the ignition timing ST are corrected to the retard side. Therefore, when the accelerator depression amount ACCP is located in the region A of FIG. 4, the fuel injection timing AinjiC and the ignition timing S
Output torque is reduced by correcting T to the retard side,
The output torque increases smoothly as the accelerator depression amount ACCP increases. As described above, the output torque smoothly increases with the increase in the accelerator depression amount ACCP. For example, when the accelerator depression amount ACCP gradually increases from “0”, a step is generated in the output torque in the region A, and the driver is disturbed. It is possible to prevent the ability from deteriorating.

(2) A retard amount Artd for correcting the fuel injection timing AinjiC and the ignition timing ST to the retard side.
Is obtained based on the accelerator depression amount ACCP with reference to the map shown in FIG. Then, as is clear from the map of FIG. 5, as the difference between the reference value ACCPA and the accelerator depression amount ACCP (“ACCPA−ACCP”) increases,
The retard amount Artd also increases. Therefore, in a state where accelerator depression amount ACCP is located within region A, an output torque corresponding to accelerator depression amount ACCP can be accurately obtained.

(3) When the accelerator depression amount ACCP is located within the region A, the fuel injection timing A is adjusted so that an output torque corresponding to the accelerator depression amount ACCP is obtained.
Both injiC and ignition timing ST are corrected to the retard side. Therefore, the fuel injection timing AinjiC and the ignition timing ST
Even during execution of "stratified combustion" in which misfiring or the like may occur due to excessive change between the accelerator pedal depression amount AC and the accelerator depression amount AC without causing misfiring by the above correction.
An output torque corresponding to the CP can be obtained.

The present embodiment can be modified, for example, as follows. In the present embodiment, the retard amount Artd is calculated using the map shown in FIG. 5, but may be calculated using an equation instead of using this map.

In the present embodiment, the retard amount Artd is determined based on the difference between the reference value ACCPA and the accelerator depression amount ACCP, but may be determined only by the accelerator depression amount ACCP. In this case, the accelerator depression amount ACC
The retard amount Artd is determined so that the retard amount Artd decreases as P increases.

In this embodiment, the accelerator depression amount ACC
When P is in the region A, the fuel injection timing AinjiC and the ignition timing ST are corrected to the retard side to reduce the output torque of the engine 11, and the accelerator depression amount AC
Although an output torque corresponding to the CP is obtained, the present invention is not limited to this. That is, the fuel injection timing Ain
Instead of correcting jiC and ignition timing ST to the retard side,
By controlling the throttle valve 23 to the closed side, the engine 11
May be increased to increase the pumping loss of the engine 11 to reduce the output torque.
When an exhaust gas recirculation (EGR) mechanism for recirculating the exhaust gas of the engine 11 to the intake system is employed in the engine 11, the opening degree of the EGR valve in the EGR mechanism is controlled to the closed side, and the intake air of the engine 11 is controlled. The output pressure may be reduced by increasing the negative pressure generated in the system to increase the pumping loss of the engine 11. Further, arbitrary cylinders # 1 to #
The output torque may be reduced by controlling the number of operating cylinders on the decreasing side by performing a fuel cut in step 4. In these cases, as the difference between the reference value ACCPA and the accelerator depression amount ACCP increases, the throttle valve 23 and the EG
It is preferable to perform control so that the closing amount of the R valve is increased and the number of operating cylinders is reduced.

Further, when the accelerator depression amount is located within the region A, a plurality of means among the above-mentioned various means for reducing the output torque of the engine 11 may be executed in combination.

In the present embodiment, the present invention is applied to the engine 11 of the type that switches the combustion method. However, the present invention may be applied to the engine 11 that performs only “homogeneous combustion”.

[0064]

According to the first aspect of the present invention, when the fuel injection amount set according to the accelerator opening is equal to or less than a predetermined minimum fuel injection amount, the minimum fuel injection amount becomes equal to the fuel injection amount. The predetermined control system for controlling the operation of the internal combustion engine is controlled to decrease the engine output torque so that the engine output torque corresponding to the accelerator opening is obtained. Therefore, when the accelerator opening changes near "0", for example, when the accelerator opening gradually increases from "0", a step in the engine output torque is prevented from deteriorating drivability. be able to.

According to the second aspect of the present invention, when the engine output torque corresponding to the accelerator opening is obtained,
Since the control amount of the predetermined control system for controlling the operation of the internal combustion engine is corrected based on the accelerator opening, the engine output torque corresponding to the accelerator opening can be obtained accurately.

According to the third aspect of the invention, in the internal combustion engine that performs stratified combustion, when the engine output corresponding to the accelerator opening is obtained, both the fuel injection timing and the ignition timing are delayed. The engine output torque is reduced to the corner side to reduce the engine output torque, and the correction makes it possible to obtain the engine output torque corresponding to the accelerator opening without causing a misfire or the like.

According to the fourth aspect of the present invention, the engine output torque is reduced by controlling the negative pressure adjusting means to a side where the negative pressure generated in the intake system of the internal combustion engine increases, and the negative pressure adjustment corresponds to the accelerator opening. The engine output torque thus obtained can be obtained.

According to the fifth aspect of the present invention, the engine output torque is reduced by controlling the number of operating cylinders of the internal combustion engine to the decreasing side, and the engine output torque corresponding to the accelerator opening can be obtained. Become like

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an entire engine to which a combustion control device according to an embodiment is applied.

FIG. 2 is a sectional view of a cylinder head showing shapes of intake and exhaust ports in the engine.

FIG. 3 is a block diagram showing an electrical configuration of the combustion control device.

FIG. 4 shows the accelerator depression amount, fuel injection amount,
6 is a time chart showing changes in a retard amount and an output torque.

FIG. 5 is a map referred to when calculating a retard amount.

FIG. 6 is a flowchart showing a combustion control procedure.

FIG. 7 is a time chart showing changes in the accelerator depression amount and the fuel injection amount over time in the related art.

[Explanation of symbols]

Reference numeral 11: engine, 16: combustion chamber, 23: throttle valve, 24: throttle motor, 25: accelerator pedal, 26: accelerator position sensor, 40: fuel injection valve, 41: spark plug, 41a: igniter, 44: throttle position Sensor, 92 ... Electronic control unit (ECU).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 17/02 F02D 17/02 U 41/10 315 41/10 315 330 330 330A 335 335 41/32 41/32 C 43 / 00 301 43/00 301B 301J 301K F02P 5/15 F02P 5/15 BF F term (reference) 3G022 AA00 AA04 AA07 CA00 CA04 DA02 EA07 GA01 GA05 GA07 GA08 3G065 AA00 AA05 CA13 DA05 DA06 EA09 FA07 GA01 GA10 GA46 3G084 AA00 AA03 AA04 BA05 BA15 BA17 CA03 CA04 DA11 FA10 FA11 FA33 FA38 3G092 AA06 AA09 AA14 BA09 BB06 CA08 DC03 EA04 EA09 FA04 GA12 HA05Z HA06Z HE01Z HE03Z HF08Z 3G301 HA01 HA04 HA07 HA04 LA17 MA04 LA04 PA11Z PE01Z PE03Z PF03Z

Claims (5)

[Claims] An accelerator opening degree is set by setting a fuel injection amount of an internal combustion engine in accordance with an accelerator opening degree and supplying an amount of fuel corresponding to the set fuel injection amount to a combustion chamber of the engine. In the combustion control device for an internal combustion engine that performs control of the engine output torque according to the following, when the fuel injection amount set according to the accelerator opening is equal to or less than a predetermined minimum fuel injection amount, the minimum fuel injection amount is A control means for setting the fuel injection amount and controlling a predetermined control system for controlling the operation of the internal combustion engine so as to obtain an engine output torque corresponding to the accelerator opening to a lower engine output torque side. A combustion control device for an internal combustion engine. 2. The combustion of an internal combustion engine according to claim 1, wherein said control means corrects a control amount of said predetermined control system based on said accelerator opening so as to obtain an engine output torque corresponding to said accelerator opening. Control device. 3. The internal combustion engine executes stratified charge combustion, and the control means delays a fuel injection timing and an ignition timing of the internal combustion engine so that an engine output torque corresponding to the accelerator opening is obtained. 3. The combustion control device for an internal combustion engine according to claim 1, wherein the correction is performed on the corner side. 4. The combustion control apparatus for an internal combustion engine according to claim 1, further comprising negative pressure adjusting means for adjusting a negative pressure generated in an intake system of the internal combustion engine, wherein said control means includes: A combustion control device for an internal combustion engine, wherein the negative pressure adjusting means is controlled to increase the negative pressure so that an engine output torque corresponding to an accelerator opening is obtained. 5. The internal combustion engine has a plurality of cylinders, and the control means controls the number of operating cylinders of the internal combustion engine to a decreasing side so as to obtain an engine output torque corresponding to the accelerator opening. The combustion control device for an internal combustion engine according to claim 1.