JPH1068338A - Control device for cylinder fuel injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shock or a drop in engine torque from generating at the changeover of a combustion mode under a lean air-fuel ratio by selecting a combustion mode according to an accelerator pedal operation quantity and engine speed, and providing a command value to a throttle acutuator at every combustion mode. SOLUTION: At operating an engine 14, a combustion mode deciding means 3 refers to fixed data based on an accelerator pedal operation quantity 101 and engine speed 102 so as to decide a combustion mode 103. A target air-fuel ratio computing means 4 computes a basic fuel injection quantity based on an intake air quantity and engine speed, prescribed data are referred and interpolated so as to decide a target air-fuel ratio, and hence a high pressure injection valve 7 is controlled. A plurality of reference data are set according to combustion modes 103, and the data in response to the combustion mode 103 is selected. In addition, a throttle opening command value computing means 5 decides a throttle opening command value 105 based on the accelerator pedal operation quantity 101 and the engine speed 102.

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 direct injection engine for directly injecting fuel into a cylinder.

[0002]

2. Description of the Related Art In order to improve fuel consumption while keeping harmful components in exhaust gas of an engine low, the fuel is controlled so that the air-fuel ratio is leaner than the stoichiometric air-fuel ratio (lean air-fuel ratio). Engines that inject directly into a cylinder have been proposed.

When the engine is operated at a lean air-fuel ratio, the amount of fuel is reduced with respect to the intake air amount of the engine as compared with the normal stoichiometric air-fuel ratio. The torque decreases. On the other hand, the catalyst does not work effectively with nitrogen oxides (NOx) in the exhaust gas except at the stoichiometric air-fuel ratio, so that the lean operation can be performed only at the air-fuel ratio where the NOx is below the allowable limit. That is, in order to satisfy the demand for the exhaust gas and suppress the change in the engine torque due to the change in the air-fuel ratio, it is necessary to optimally control the intake air amount and the supplied fuel amount with the shift of the air-fuel ratio. Japanese Patent Application No. 6-172292 provides this control method.

[0004]

However, in the in-cylinder injection engine which is the object of the present invention, Japanese Patent Application Laid-Open No. 60-30420 and Japanese Patent Application Laid-Open No.
According to the air-fuel ratio as proposed in 11907,
It is necessary to have a plurality of combustion modes, and it is necessary to optimally control the amount of intake air and the amount of fuel supplied when shifting these combustion states. Japanese Patent Application No. 6-172292 discloses that viewpoint. Is missing.

An object of the present invention is to provide a method of controlling an engine without a shock or a decrease in engine torque even when the combustion mode is switched at a lean air-fuel ratio.

[0006]

In order to achieve the above object, the present invention has means for selecting a combustion mode according to an accelerator pedal operation amount and an engine speed, and determining a command value to a throttle actuator. Data for each combustion mode.

[0007]

Embodiments of the present invention will be described below.

FIG. 1 shows the overall configuration of this embodiment. In this embodiment, an accelerator pedal operation amount sensor 1, an engine speed sensor 2, an intake amount sensor 9, a throttle actuator 10, a spark plug 8, a high pressure injection valve 7 for directly injecting fuel into a cylinder, and fuel to a high pressure injection valve. High pressure fuel pump 13 to be supplied, air-fuel ratio sensor 11, catalyst 12, and control device 13
The feature of the present invention lies in a control method of the control device 13.

In the control device 13, the combustion mode determining means 3 determines the combustion mode 103 from the accelerator pedal operation amount 101 and the engine speed 102. Target air-fuel ratio
After 104 is calculated by the target air-fuel ratio calculating means 4 according to the combustion mode, the fuel injection amount 106 is calculated by the fuel injection amount calculating means 6. On the other hand, the throttle opening command value 10
5 is calculated by the throttle opening command value calculating means 5 in accordance with the combustion mode 103.

The operation of the combustion mode determining means 3, target air-fuel ratio calculating means 4, throttle opening calculating means 5, and fuel injection amount calculating means 6 will be described below with reference to flowcharts.

FIG. 2 is a flowchart showing the operation of the combustion mode calculation means. After inputting the accelerator pedal operation amount 101 and the engine speed 102 in steps S1 and S2, in step S3, data set in advance in the control device 13 is searched to determine the combustion mode 103. The combustion mode 103 determined in this way is not necessarily absolute, and may be changed to another mode depending on the state of the engine.

FIG. 3 is a flowchart showing the operation of the target air-fuel ratio calculating means 4. After inputting the intake air amount and the engine speed 102 in processing S4 and processing S5, the basic fuel injection amount is calculated in processing S6, and in processing S9 or processing S10,
The target air-fuel ratio 104 is determined by searching and interpolating data set in the control device 13 in advance. A plurality of data to be searched are set according to the combustion mode 103, and data corresponding to the combustion mode 103 is selected in step S7 or step S8.

FIG. 4 shows a throttle opening command value calculating means 5.
6 is a flowchart showing the operation of the first embodiment. In steps S11 and S12, the accelerator pedal operation amount 101 and the engine speed
After inputting 102, in step S13, data set in advance in the control device 13 is searched and interpolated to calculate a target basic fuel amount. Then, the process S16 or the process S1
In step 7, data set in advance in the control device 13 is searched and interpolated to determine the throttle opening command value 105. A plurality of data to be searched are set in accordance with the combustion mode 103, and data corresponding to the combustion mode 103 is selected in step S14 or step S15.

FIG. 5 is a flowchart showing the operation of the fuel injection amount calculating means 6. In steps S19, S20, S21, and S22, the accelerator pedal operation amount 1
After inputting 01, the target air-fuel ratio 104, the basic fuel amount, and the target basic fuel amount, it is determined in a process S23 whether or not the combustion mode transition period is in progress. Replace with fuel quantity. Thereafter, the fuel injection amount 106 is calculated in step S25. The transition to the combustion mode is a period determined according to the state of the engine after the combustion mode 103 is changed.

[0015]

According to the present invention, an engine whose output hardly changes even when the mode is switched between the combustion modes can be operated without the driver being conscious of the change in the combustion mode at all.

[Brief description of the drawings]

FIG. 1 is a block diagram of the overall configuration of an embodiment.

FIG. 2 is an explanatory diagram of the operation of a combustion mode calculation means.

FIG. 3 is an explanatory diagram of an operation of a target air-fuel ratio calculating means.

FIG. 4 is an explanatory diagram of the operation of a throttle opening command value calculating means.

FIG. 5 is an explanatory diagram of the operation of a fuel injection amount calculating means.

Claims (4)

[Claims] A fuel injection means for injecting fuel directly into a cylinder;
In a direct injection engine having a plurality of lean air-fuel ratio combustion modes according to a fuel injection state, a combustion mode is determined according to an accelerator pedal operation amount and an engine speed. Means for injecting fuel directly into the cylinder;
In a direct injection engine having a plurality of lean air-fuel ratio combustion modes according to the fuel injection state, the in-cylinder injection engine has, for each combustion mode, data previously stored in a control device for determining an air-fuel ratio. Control device for the direct injection engine. 3. A cylinder having a plurality of lean air-fuel ratio combustion modes according to a fuel injection state, comprising means for directly injecting fuel into a cylinder, and an actuator capable of controlling an intake amount independently of an accelerator pedal operation amount. A control device for an in-cylinder injection engine, wherein the injection engine has data stored in the control device in advance for each combustion mode in order to determine a command value to the actuator. 4. An in-cylinder injection engine having a means for directly injecting fuel into a cylinder and an actuator capable of controlling an intake air amount independently of an accelerator pedal operation amount, and having a plurality of lean air-fuel ratio combustion modes according to a fuel injection state. , An engine control device characterized in that when shifting the combustion mode, the fuel supply amount is determined according to the accelerator pedal operation amount and the engine speed for a certain period of time.