JP2002004917A - Control device for onboard internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an on-vehicle internal combustion engine, capable of improving braking performance while inhibiting the increase of fuel consumption even when an inlet pressure becomes a value closer to the atmospheric pressure than a required value for the operation of a brake booster. SOLUTION: The control device comprises the brake booster 50 for generating assisting force in accordance with the inner pressure of the booster in which the inlet pressure is accumulated and a throttle motor 24 for changing the inlet pressure. The motor 24 is controlled so that, during releasing an acceleration pedal 25, the inlet pressure becomes a value closer to a vacuum than an inlet pressure in the state of footing the pedal 25. A short time up to keeping the inner pressure of the booster is required, because the inlet pressure is changed to the value closer to the vacuum during releasing the acceleration pedal 25. Pumping loss is reduced because the inlet pressure is decreased only when the inner pressure of the booster should be kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a vehicle-mounted internal combustion engine mounted on a vehicle such as an automobile having a brake booster for generating an assisting force for reducing the depression force on a brake pedal.

[0002]

2. Description of the Related Art Generally, a brake system for a vehicle such as an automobile includes a master cylinder that generates a hydraulic pressure according to a depression force when a driver depresses a brake pedal, and a brake that generates an assist force for reducing the depression force. A booster is provided. This brake booster has a negative pressure chamber and an atmosphere chamber partitioned by a diaphragm,
The intake pressure generated in the intake passage is introduced into the negative pressure chamber and accumulated as booster internal pressure. When the driver depresses the brake pedal, the negative pressure chamber and the atmosphere chamber are shut off, and the atmosphere enters the atmosphere chamber. The differential pressure between the internal pressure of the booster acting on the diaphragm and the atmospheric pressure causes the brake booster to generate the assist force. It is supposed to.

[0003] In recent years, as a vehicle-mounted internal combustion engine such as an automobile engine, an internal combustion engine of a type in which a combustion mode is switched according to an engine operating state has been proposed and put into practical use.
Such a type of internal combustion engine performs, for example, `` homogeneous combustion '' in which, when high output and high rotation and high load are required, a homogeneous mixture in which fuel is evenly mixed with air is burned,
At low rotation speed and low load where very high output is not required, "stratified combustion" is performed.

[0004] The homogeneous combustion is carried out by uniformly mixing fuel directly injected into an engine combustion chamber with air in the combustion chamber during an intake stroke of the internal combustion engine, and igniting the air-fuel mixture by a spark plug. You. On the other hand, stratified combustion
In the compression stroke of the internal combustion engine, the fuel directly injected into the engine combustion chamber hits the depression in the piston head and is collected around the spark plug, and a mixture of the collected fuel and air in the combustion chamber is ignited by the spark plug. It is executed by doing. In this stratified combustion, it is possible to improve the ignitability by increasing the fuel concentration around the spark plug and improve the fuel efficiency by setting the average air-fuel ratio of the air-fuel mixture to a value leaner than the stoichiometric air-fuel ratio. . In such stratified combustion,
Since 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, pumping loss is reduced.

When the above-mentioned brake booster is applied to an on-vehicle internal combustion engine that performs such stratified combustion, the opening of the throttle valve during stratified combustion becomes a value on the opening side as compared with that during homogeneous combustion, so that it occurs in the intake passage. The intake pressure becomes a value on the atmospheric pressure side from the required value for operating the brake booster,
The booster internal pressure required to operate the brake booster cannot be secured.

Therefore, when the booster internal pressure has not reached the required value (when it is a value on the atmospheric pressure side from the required value), the opening of the throttle valve is changed from a preset value to a value on the closing side. It has been proposed to perform a closing control to change the pressure, thereby changing the intake pressure to the vacuum side, and securing a necessary booster internal pressure lower than a required value (for example, Japanese Patent Application Laid-Open No. 10-151970).

When performing the closing control, there is a response delay from when the throttle valve starts to be closed to when the intake pressure in the intake passage decreases and the booster internal pressure decreases. The delay deteriorates the braking performance.

Therefore, conventionally, the degree of opening of the throttle valve during stratified charge combustion is set to a value close to a certain degree in advance to shorten the time until a necessary booster internal pressure is secured.

[0009]

However, if the opening of the throttle valve during stratified charge combustion is set to a certain value on the closed side in advance, the pumping loss of the internal combustion engine during stratified charge combustion increases, and fuel consumption deteriorates. There was a problem that would invite.

The present invention has been made in view of such circumstances, and has as its object to reduce fuel consumption even when the intake pressure becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster. It is an object of the present invention to provide a control device for an in-vehicle internal combustion engine capable of improving the braking performance while suppressing the occurrence of vibration.

[0011]

The means for solving the above problems and the operation and effects thereof will be described below. In order to solve the above-mentioned problem, the invention according to claim 1 includes a brake booster that generates an assist force for reducing a depression force of a brake pedal based on a booster internal pressure in which an intake pressure generated in an intake passage is accumulated; An actuator for changing the air pressure, wherein when the booster internal pressure is a value on the atmospheric pressure side from a required value required for the operation of the brake booster, the on-board internal combustion controller controls the actuator to change the intake pressure to a vacuum side. In the engine control device, when the accelerator pedal is released, the intake pressure becomes a value on the vacuum side of the intake pressure when the accelerator pedal is depressed for the same engine operating state. It is characterized by comprising control means for controlling the actuator.

According to the present invention, when the accelerator pedal is released, the intake pressure generated in the intake passage is on the vacuum side of the intake pressure when the accelerator pedal is depressed for the same engine operating state. The actuator is controlled to be a value. For this reason, the driver usually releases the accelerator pedal before depressing the brake pedal, so when the booster internal pressure becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster, the intake pressure is reduced to the value on the vacuum side. Can be changed early.

In this way, only when it is necessary to secure the booster internal pressure to a value on the vacuum side of the required value required for the operation of the brake booster, the intake pressure is reduced, so that the pumping loss is reduced. Further, when the accelerator pedal is released, the intake pressure is changed to a value on the vacuum side, so that the time until the necessary booster internal pressure is secured can be shortened. Therefore, even when the intake pressure becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster, it is possible to improve the braking performance while suppressing the deterioration of the fuel consumption.

According to a second aspect of the present invention, in the first aspect of the present invention, the control of the actuator by the control means is performed during execution of stratified combustion. According to the present invention, it is possible to prevent an increase in pumping loss of the internal combustion engine during stratified charge combustion, and to prevent deterioration of fuel efficiency due to the increase. Therefore, even during the execution of stratified charge combustion, it is possible to improve braking performance while suppressing deterioration of fuel efficiency.

According to a third aspect of the present invention, in the first or second aspect of the invention, the actuator changes an intake pressure by changing an opening degree of a valve, and the control means controls the valve operation. Is set such that, for the same engine operating state, the intake pressure when the accelerator pedal is released is a value on the vacuum side of the intake pressure when the accelerator pedal is depressed, The actuator is controlled based on the set value.

According to the present invention, the set opening of the valve is
By setting the time when the accelerator pedal is released and the time when the accelerator pedal is depressed, it is possible to improve the braking performance while suitably suppressing the deterioration of the fuel efficiency.

According to a fourth aspect of the present invention, in the third aspect of the invention, when the accelerator pedal is depressed, the control means sets the engine operating state such that the intake pressure becomes relatively high. The set opening of the valve is set based on the first map in which the set opening of the valve is set accordingly, and the intake pressure is relatively reduced when the accelerator pedal is released. In which the set opening degree is set according to the engine operating state.
The set opening degree of the valve is set based on the map.

According to the present invention, when the accelerator pedal is depressed and when the accelerator pedal is released, the set opening of the valve can be appropriately set according to the engine operating state. . As a result, it is possible to improve the braking performance while appropriately suppressing the deterioration of the fuel efficiency according to the engine operating state.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is applied to a control device for an in-cylinder injection type vehicle-mounted internal combustion engine will be described below with reference to FIGS.

As shown in FIG. 1, in a cylinder block 11a of the engine 11, a piston 12 is provided for each cylinder so as to be able to reciprocate. The head of each piston 12 is formed with a depression 12a necessary for performing stratified combustion. Each piston 12 is connected to a crankshaft 14 via a connecting rod 13.

In the vicinity of the crankshaft 14, there is provided a rotation speed sensor 14a for detecting the rotation speed of the shaft 14 (engine rotation speed NE) and the rotation angle of the shaft 14 (crank angle CA).

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. An intake port 17 and an exhaust port 18 provided in the cylinder head 15 communicate with the combustion chamber 16, respectively.
The intake port 17 and the exhaust port 18 are provided with an intake valve 19 and an exhaust valve 20, respectively.

On the other hand, the cylinder head 15 rotatably supports an intake camshaft 21 and an exhaust camshaft 22 for opening and closing the intake valve 19 and the exhaust valve 20, respectively. The rotation of the crankshaft 14 is transmitted to the intake camshaft 21 and the exhaust camshaft 22 via a timing belt and gears (not shown). The rotation of the intake camshaft 21 drives the opening and closing of the intake valve 19, and the rotation of the exhaust camshaft 22 drives the opening and closing of the exhaust valve 20. A cam position sensor 21a for detecting the rotation angle of the intake camshaft 21 is provided on the side of the intake camshaft 21 of the cylinder head 15.

The intake port 17 and the exhaust port 18
An intake pipe 30 and an exhaust pipe 31 are connected to each other.
The inside of the intake pipe 30 and the intake port 17 is an intake passage 32, and the inside of the exhaust pipe 31 and the exhaust port 18 is an exhaust passage 33. A throttle valve 23 is provided in an upstream portion of the intake passage 32. The throttle valve 23 is opened and closed by a throttle motor 24 as an actuator. Throttle valve 2
3 (throttle opening TA) is detected by the throttle position sensor 44. In the vicinity of the accelerator pedal 25, the amount of depression (accelerator opening AC
An idle switch 45 that outputs an ON signal in a region where CP) is equal to or less than a predetermined value (for example, 0.5 °) is provided.

Downstream of the throttle valve 23 in the intake passage 32, a vacuum sensor 36 for detecting an intake pressure PM generated in the passage 32 is provided. A brake booster 50 is connected to the intake passage 32 downstream of the throttle valve 23 via a negative pressure passage 49.

The brake booster 50 generates an assist force for reducing the depression force of the brake pedal 51 based on the booster internal pressure PBK in which the intake pressure PM generated in the intake passage 32 is accumulated. That is, the brake pedal 51
When is not depressed, the atmosphere chamber and the negative pressure chamber (not shown) in the brake booster 50 communicate with each other. Therefore, the intake pressure PM is stored in the atmosphere chamber and the negative pressure chamber as the booster internal pressure PBK through the negative pressure passage 49 and a check valve (not shown) provided in the negative pressure passage 49. Brake pedal 5
When step 1 is depressed, the atmosphere chamber and the negative pressure chamber are shut off and the atmosphere chamber is released to the atmosphere, and the differential pressure between the atmospheric pressure PA introduced into the atmosphere chamber and the booster internal pressure PBK stored in the negative pressure chamber (booster operation) The pressure DPBK acts on the diaphragm to generate an assist force according to the pedaling force. With this power,
By pressing a piston of a master cylinder (not shown), the master cylinder generates a hydraulic pressure according to the pedaling force.

The assist force is applied to the brake booster 5
To generate 0, the booster internal pressure PBK needs to be a value on the vacuum side of the required value required for operation. This is because, when the booster internal pressure PBK is a value on the atmospheric pressure side from the required value, the assist force generated by the brake booster 50 becomes smaller, and the driver depresses the brake pedal 51 with a stronger pedal force than usual. is there.

The booster internal pressure PBK is detected by a booster pressure sensor 50a. Further, the brake pedal 51 is provided with a brake switch 51a for detecting depression of the pedal.

The combustion chamber 1 is provided in the cylinder head 15.
A fuel injection valve 40 for injecting fuel into the fuel cell 6 and an ignition plug 41 for igniting a mixture of fuel and air charged in the combustion chamber 16 are provided. This spark plug 41
Is adjusted by an igniter 41 a provided above the ignition plug 41.

When fuel is injected from the fuel injection valve 40 into the combustion chamber 16, the fuel is mixed with air drawn into the combustion chamber 16 through the intake passage 32, and
A mixture of air and fuel is formed in 6. 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 combustion is sent to the exhaust passage 33 as exhaust gas.

Further, the downstream side of the throttle valve 23 in the intake passage 32 communicates with the exhaust passage 33 via an exhaust gas recirculation passage (EGR passage) 42. This EGR passage 4
2 includes a step motor 43a as an actuator
An EGR valve 43 provided with And
The opening of the EGR valve 43 (EGR opening) is adjusted by controlling the drive of the step motor 43a. By this opening degree adjustment, the amount of exhaust gas (EGR amount) recirculated to the intake passage 32 via the exhaust passage 33 is adjusted. Then, the exhaust gas of the engine 11 is recirculated to the intake passage 32, so that the combustion temperature is reduced, the generation of nitrogen oxides (NOx) is suppressed, and the NOx emission is reduced.

Next, the electrical configuration of the control device for a vehicle-mounted internal combustion engine according to this embodiment will be described with reference to FIG. This control device is used to secure the booster internal pressure PBK of the brake booster 50 in addition to various controls such as control for switching the combustion mode of the engine 11 based on the engine operating state such as the load factor and the engine speed NE. An electronic control unit (hereinafter, referred to as “ECU”) 92 for performing control is provided. The ECU 92 constitutes control means for controlling the throttle motor 24 or the step motor 43a as an actuator. The ECU 92
Is composed of a ROM 93, a CPU 94, a RAM 95, a backup RAM 96, and the like.

The ROM 93 is a memory in which various control programs and maps (for example, the maps shown in FIGS. 4 and 5) referred to when executing these programs are stored. The arithmetic processing is executed based on the stored various control programs and maps.

The RAM 95 is a memory for temporarily storing the calculation results of the CPU 94, data input from each sensor, and the like.
1 is a non-volatile memory for storing the stored data and the like at the time of stopping. And ROM93, CPU94,
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 includes a rotational speed sensor 1
4a, a cam position sensor 21b, an accelerator position sensor 26, a vacuum sensor 36, a throttle position sensor 44, an idle switch 45, a booster pressure sensor 50a, a brake switch 51a, and the like are connected. On the other hand, the throttle output motor 24, the fuel injection valve 40, the igniter 41a, the EGR valve 43, and the like are connected to the external output circuit 99.

The ECU 92 controls, for example, switching of the combustion mode. In this switching control, when the engine operation state shifts to the high-load high-speed region, the combustion mode of the engine 11 is set to the homogeneous combustion. In this case, the fuel injection timing is set, for example, during the intake stroke or during the period from the intake stroke to the first half of the compression stroke, and the fuel injected into the combustion chamber 16 is almost uniformly mixed with the intake air in the combustion chamber. Burned in. Further, at the time of the homogeneous combustion, the ratio between the intake air amount GA and the basic fuel injection amount Q, which changes in accordance with the intake pressure PM and the engine speed NE, that is, the air-fuel ratio becomes the stoichiometric air-fuel ratio. The required fuel injection amount Q is calculated based on the obtained load factor and the engine speed NE. Further, since the intake air amount GA is adjusted according to the throttle opening TA, the output of the engine 11 during homogeneous combustion is adjusted by the throttle valve 23.

In the combustion mode switching control performed by the ECU 92, when the operating state of the engine shifts to the low-load low-speed range, the combustion mode of the engine 11 is set to stratified combustion.
In this case, the fuel injection timing is set in the latter half of the compression stroke, and most of the fuel injected into the combustion chamber 16 is burned in a state unevenly distributed near the ignition plug 41. At the time of such stratified combustion, the air-fuel ratio is leaner than the stoichiometric air-fuel ratio,
The basic fuel injection amount Q is calculated based on the accelerator opening ACCP, the load factor obtained from the air conditioner load, the electric load, and the like, and the engine speed NE.

In addition to such combustion mode switching control, E
CU92 is a booster internal pressure PB of the brake booster 50.
A booster internal pressure securing process for securing K is performed. This control is performed during the execution of stratified combustion, and the booster internal pressure P
When BK is a value on the atmospheric pressure side from the required value required for the operation of the brake booster 50, the drive of the throttle motor 24 and the step motor 43a as actuators is controlled so as to change the intake pressure PM to a value on the vacuum side. That is, when the booster internal pressure PBK becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster 50, the throttle opening TA and the EGR opening are changed from the preset target opening to the closing opening. A closing control is performed to change the intake pressure PM to the vacuum side, thereby securing a necessary booster internal pressure PBK lower than a required value.

The ECU 92 sets target opening of the throttle valve 23 and the EGR valve 43 during stratified charge combustion, based on the engine operating conditions such as the load factor and the engine speed NE. Further, during stratified charge combustion, the ECU 92 sets the intake pressure PM when the accelerator pedal 25 is released.
The opening degree of the throttle valve 23 or the EGR valve 43 is set so that the value becomes a value on the vacuum side of the intake pressure PM when the pedal is depressed.

Hereinafter, a process for setting the throttle opening TA during the stratified combustion will be described with reference to FIGS. FIG. 3 is a flowchart showing a procedure of a throttle opening setting process at the time of stratified combustion. A series of processes shown in this flowchart is repeatedly executed by the ECU 92 at predetermined control cycles.

In this series of processes, it is first determined whether or not stratified combustion is being performed (step S110). This determination is made based on the engine operating state such as the load factor and the engine speed NE, as in the case of the control for switching the combustion mode. If the engine operating state is not in the low-load low-speed range, it is determined that stratified combustion is not being executed (NO in step S110), and this series of processing is temporarily ended.

This is because, when the engine is operating in the high-load and high-speed region and the homogeneous combustion is being performed, the booster internal pressure PBK usually becomes a value on the vacuum side from the required value required for the operation of the brake booster 50. This is because there is no need to reduce the intake pressure PM.

If the engine operating state has shifted to the low-load low-speed region, it is determined that stratified combustion is being performed (YES in step S110), and the routine proceeds to step S120. In this step, it is determined whether or not the accelerator pedal 25 is released. This determination is made, for example, based on whether or not the idle switch 45 outputs an ON signal. That is, if the accelerator pedal 25 is depressed and the accelerator opening is greater than the predetermined value, the idle switch 45 outputs an off signal, and therefore, step S
The determination at 120 is NO, and the process proceeds to step S130.

In step S130, the first map shown in FIG. 4 is searched to set a target throttle opening TAt for stratified charge combustion based on the engine speed NE and the load factor. This first map is stored in the ROM 93 in advance. In the map, the target throttle opening degree TA is set in accordance with the engine speed NE and the load factor so that the intake pressure PM becomes relatively high. Where "load factor"
Is the ratio of the required load (required generated torque) obtained from the accelerator opening ACCP, the air conditioner load, the electric load, etc., to the maximum load (maximum generated torque) at the engine rotational speed NE. The target throttle opening TAt set in the first map is set to be an optimum throttle opening in terms of fuel efficiency according to the load factor and the engine speed NE.

Thereafter, the process proceeds to step S150, in which the driving of the throttle motor 24 is controlled such that the actual throttle opening TA approaches the target throttle opening TAt set by searching the first map. After the execution of step S150, a series of processes is temporarily ended.

When the driver releases the accelerator pedal 25 during the stratified charge combustion operation, the pedal returns to the predetermined value and the idle switch 45 outputs an ON signal. No, and the process proceeds to the next step S140.

In step S140, the second map shown in FIG. 5 is searched to set a target throttle opening TAt during stratified charge combustion based on the engine speed NE and the load factor. This second map is also stored in the ROM 93 in advance. In the second map, the target throttle opening degree TAt is set in accordance with the engine speed NE and the load factor so that the intake pressure PM becomes relatively lower than in the first map. That is, in the second map, with respect to the first map,
The same engine operating state, that is, load factor and engine speed NE
Are the same, the throttle opening on the closing side of the target throttle opening TAt set in the first map is set. The target throttle opening TAt set in the second map is used to secure the braking performance by changing the intake pressure PM to a value on the vacuum side early when performing the booster internal pressure securing process described above. The throttle opening is set to be an indispensable closing side throttle. For example, for an engine operating state in which the engine speed NE is 800 rpm and the load factor is 75%, the target throttle opening TAt is set to about 15% in the first map, while 5% in the second map. % Is set.

Thereafter, the routine proceeds to step S150, in which the throttle motor 24 is drive-controlled so that the actual throttle opening TA approaches the target throttle opening TAt set by searching the second map. As a result, even in the same engine operation state, when the accelerator pedal 25 is released, the throttle valve 23 is displaced to the closing side as compared with when the pedal is depressed, and the intake pressure PM decreases. Therefore, when the booster internal pressure PBK becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster 50, the intake pressure PM can be changed to a value on the vacuum side early, and the necessary booster internal pressure PBK can be obtained. Can be shortened. After the execution of step S150, the series of processes illustrated in FIG. 3 is temporarily ended.

According to the first embodiment described above, the following operational effects can be obtained. (1) When the driver releases his / her foot from the accelerator pedal 25 and releases the pedal during stratified charge combustion, when the intake pressure PM is depressed for the same engine operating state, Of the throttle motor 24 is controlled so as to be a value on the vacuum side of the intake pressure PM. As a result, the throttle valve 23 is displaced closer to the closed side than when the accelerator pedal 25 is depressed, and the intake pressure PM changes to the vacuum side. As a result, when the booster internal pressure PBK becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster 50, the intake pressure PM can be changed to a value on the vacuum side early.

In this manner, the intake pressure PM is reduced only when the booster internal pressure PBK needs to be maintained at a value on the vacuum side of the required value required for the operation of the brake booster 50, so that the pumping loss is reduced. Further, when the accelerator pedal 25 is released, the intake pressure PM is changed to a value on the vacuum side, so that the time until the necessary booster internal pressure is secured can be shortened. Therefore, even when the intake pressure PM becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster 50, the brake performance can be improved while suppressing the deterioration of the fuel efficiency.

(2) Since the control of the throttle motor 24 as an actuator by the ECU 92 is performed during stratified charge combustion, the pumping loss of the internal combustion engine during stratified charge combustion does not increase, and deterioration of fuel efficiency due to the increase can be prevented. Therefore, even when the intake pressure PM becomes a value on the atmospheric pressure side from the required value required for the operation of the brake booster 50 during execution of stratified combustion, it is possible to improve the braking performance while suppressing the deterioration of the fuel consumption.

(3) The ECU 92 as the control means adjusts the set opening of the throttle valve 23 to the intake pressure PM when the accelerator pedal 25 is released for the same engine operating state. Is set to a value on the vacuum side of the intake pressure PM when the throttle valve is turned on, and the throttle motor 24 is controlled based on the set value. Thus, by setting the opening degree of the throttle valve 23 when the accelerator pedal 25 is released and when the accelerator pedal 25 is depressed, it is possible to improve the braking performance while appropriately suppressing the deterioration of the fuel consumption. Can be achieved.

(4) The ECU 92 controls the throttle valve 2
3 is set based on the first map set so that the intake pressure PM is relatively high when the accelerator pedal 25 is depressed, and when the accelerator 25 is released, The intake pressure PM is set based on a second map set according to the engine operating state so as to be relatively low. Thus, the set opening of the throttle valve 23 can be appropriately set according to the engine operating state when the accelerator pedal 25 is depressed and when the accelerator pedal 25 is released. Thereby, at the time of stratified combustion, it is possible to improve the braking performance while appropriately suppressing the deterioration of the fuel efficiency.

Although the embodiment of the present invention has been described above, the present embodiment can be implemented by changing its configuration as described below. In the above embodiment, the opening degree of the throttle valve 23 is set using the map when the accelerator pedal 25 is depressed and when the accelerator pedal 25 is released. The target throttle opening is set using a map such as the first map only when the accelerator pedal 25 is depressed, and when the accelerator pedal 25 is released, the target throttle opening is determined from a value set by this map. The target throttle opening may be set by subtracting the value. Also, the target throttle opening is set using a map such as the second map only when the accelerator pedal 25 is released, and when the accelerator pedal 25 is depressed, the target throttle opening is set to a value set by this map. The target throttle opening may be set by adding a predetermined value.

In the above embodiment, the accelerator pedal 25
Is released, the opening degree of the throttle valve 23 is changed to the closing side so that the intake pressure PM becomes a value on the vacuum side. In addition to the opening degree setting of the throttle valve 23, the EGR The set opening of the valve 43 may also be changed to the closed side so that the intake pressure PM becomes a value on the vacuum side. In this case, the target EGR opening may be set using a map or the like when the accelerator pedal 25 is depressed and when the accelerator pedal 25 is released.

In the above-described embodiment, the intake pressure PM differs between when the accelerator pedal 25 is depressed and when the accelerator pedal 25 is released, even in the same engine operating state. Accordingly, when the ignition timing and the injection timing at which the optimum combustion state is obtained also have different values, the ignition timing setting map and the injection timing setting map of the first group corresponding to the first map, The ignition timing setting map and the injection timing setting map of the second group are stored in the ROM 93 in correspondence with the second map. When the accelerator pedal 25 is depressed, the ignition timing and the injection timing are set based on the map of the first group. When the accelerator pedal 25 is released, the ignition timing and the injection timing are determined based on the map of the second group. Should be set.

In the above-described embodiment, the present invention is applied to the in-cylinder injection type vehicle mounted internal combustion engine capable of switching the combustion mode between the homogeneous combustion and the stratified combustion. The present invention is also applicable to a vehicle-mounted internal combustion engine having a value on the atmospheric pressure side from the required value required for the operation of the engine 50. For example, such as a port injection type vehicle-mounted internal combustion engine that performs lean combustion or a vehicle-mounted internal combustion engine that adjusts the intake air amount by controlling the opening / closing timing of an intake valve, it is necessary to perform the booster internal pressure securing process described above. The present invention may be embodied.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a control device for a vehicle-mounted internal combustion engine according to a first embodiment.

FIG. 2 is a block diagram showing an electrical configuration of the control device.

FIG. 3 is a flowchart showing a throttle opening setting process during stratified charge combustion by the control device.

FIG. 4 is a schematic diagram showing a first map used for setting a throttle opening by the control device.

FIG. 5 is a schematic diagram showing a second map used for setting a throttle opening by the control device.

[Explanation of symbols]

11: engine, 23: throttle valve, 24: throttle motor as actuator, 25: accelerator pedal, 43a: step motor as actuator, 50: brake booster, 51: brake pedal, 92: electronic control unit as control means .

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) KA16 LA03 LC03 LC04 NC04 NE06 PA07Z PA11Z PA14Z PB03Z PD15Z PE01Z PE03Z PF03Z PF05Z

Claims (4)

[Claims] A brake booster that generates an assist force for reducing a depression force of a brake pedal based on a booster internal pressure in which an intake pressure generated in an intake passage is accumulated;
An actuator for changing the intake pressure, wherein when the booster internal pressure is a value on the atmospheric pressure side from a required value required for the operation of the brake booster, the vehicle controls the actuator to change the intake pressure to a vacuum side In the control device for an internal combustion engine, when the accelerator pedal is released, the intake pressure becomes a value on the vacuum side of the intake pressure when the accelerator pedal is depressed for the same engine operating state. A control device for a vehicle-mounted internal combustion engine, comprising: a control unit that controls the actuator. 2. The control device for a vehicle-mounted internal combustion engine according to claim 1, wherein the control of the actuator by the control means is performed when stratified combustion is executed. 3. The actuator according to claim 1, wherein the actuator changes the opening degree of the valve to change the intake pressure, and the control means sets the opening degree of the valve to the accelerator pedal for the same engine operating state. The intake pressure is set to a value on the vacuum side of the intake pressure when the accelerator pedal is depressed, and the actuator is controlled based on the set value. Item 3. The control device for a vehicle-mounted internal combustion engine according to item 1 or 2. 4. The control device according to claim 1, wherein when the accelerator pedal is depressed, a first opening of the valve is set according to an engine operating state such that the intake pressure becomes relatively high. Based on the map, the set opening of the valve was set, and when the accelerator pedal was released, the set opening was set according to the engine operating state so that the intake pressure became relatively low. Second
The control device for a vehicle-mounted internal combustion engine according to claim 3, wherein the set opening degree of the valve is set based on the map (3).