JPH06129276A - Fuel injection control device of engine - Google Patents

Abstract

PURPOSE:To carry out more precise air-fuel ratio control by making target torque gained from acceleration opening and engine speed parameter to decide an air-fuel ratio. CONSTITUTION:In accordance with target torque gained from acceleration opening and engine speed, an air-fuel ratio is enumerated (step 1). When the relative enumerated air-fuel ratio is changed in the lean direction at the time of torque increase, annealing treatment of the air-fuel ratio is carried out (steps 2, 4, 5).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel injection control device, and more particularly to an engine fuel injection control device which performs air-fuel ratio control using a target torque as a parameter.

[0002]

2. Description of the Related Art Conventionally, when performing air-fuel ratio control, control was performed so as to obtain a target air-fuel ratio value experimentally obtained from the engine speed and the intake air amount (or intake pipe pressure). In this case, there is no information about the torque change when the air amount changes, and it is corrected by the value obtained experimentally (reference value experimentally obtained from the air amount by actually operating the engine). It Therefore, there arises a problem that there is no torque step (discontinuous change) when the air amount changes, and there is no smoothness of the torque curve when the air amount increases by a constant amount. This is also due to the fact that there is a region where the torque hardly changes even when the air amount changes, and a region where the torque largely changes even when the air amount hardly changes.

[0003]

The present invention has been made based on such a technical background. By using a target torque obtained from the accelerator opening and the engine speed as a parameter for determining the air-fuel ratio, It is designed to enable more precise air-fuel ratio control.

[0004]

In order to solve such a problem, according to the present invention, it is provided with a means for calculating an air-fuel ratio based on a target torque obtained from an accelerator opening and an engine speed. A fuel injection control device for an engine is provided.

[0005]

According to the above configuration, the size of the torque step is estimated by using the target torque, which can be freely set to a value suitable for the engine, as the parameter for determining the air-fuel ratio from the accelerator opening and the engine speed. Therefore, the step shock can be reduced, and the torque curve when the air amount increases can be made smooth.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration of an apparatus according to the present invention, in which an engine control computer COMP incorporates an accelerator opening ACP and an engine speed NE. Then, in the engine control computer, instead of the conventional NE-air amount based air-fuel ratio map, NE-target torque TRQ
The air-fuel ratio map by Table 1 shows an example of a map for calculating the air-fuel ratio from the engine speed NE (rpm) and the target torque TRQ (kg · m).

[0007]

[Table 1]

Further, the target torque TRQ is obtained from the engine speed NE and the accelerator opening ACP, and the correlation between the accelerator opening ACP and the target torque TRQ with the engine speed (rpm) as a parameter is shown. 4 is illustrated. By thus setting the accelerator opening ACP as a parameter, the rising of the target torque TRQ can be freely set with respect to the depression amount of the accelerator pedal. Further, since the information on the torque change due to the change in the accelerator opening and the engine speed can be obtained, the size of the torque step can be estimated, and therefore the step shock can be reduced when the fuel is cut or the fuel is increased.

FIG. 2 exemplifies the processing procedure for calculating the air-fuel ratio control value performed by the engine control computer shown in FIG. 1. In step 1, the map shown in Table 1 above is used as the basis. Above engine speed NE
The air-fuel ratio is calculated from the target torque TRQ and the target torque TRQ. Next, at step 2, it is judged whether or not there is a torque increase by comparing the previously calculated target torque with the currently calculated target torque. Then, in the case of knowing (that is, in the steady state), the routine proceeds to step 3, and the value calculated in the above step 1 is directly used as the value of the air-fuel ratio.

On the other hand, when the determination in step 2 is YES (that is, in the acceleration state in which the torque is increased), the air-fuel ratio previously calculated in step 4 is calculated this time (calculated in step 1 above). It is determined whether or not it is equal to or higher than the air-fuel ratio. When the answer is yes (that is, when the air-fuel ratio calculated this time is richer), the routine proceeds to step 6, where the value calculated in step 1 above is used as is as the value of the air-fuel ratio, but when the answer is no ( That is, when the air-fuel ratio calculated this time is leaner, in step 5, the air-fuel ratio is smoothed (that is, the calculated air-fuel ratio is not set to the value of the calculated air-fuel ratio all at once, but the calculated air-fuel ratio is gradually increased. (Increase to the value of the fuel ratio), and the value subjected to the anneal processing in step 6 is set as the value of the air-fuel ratio this time.

Thus, when the calculated air-fuel ratio is larger than the value calculated last time (in the lean direction) at the time of increasing the torque, the calculated value is used as it is (that is, it is suddenly changed to the lean direction). However, since a shock such as poor acceleration occurs, the above-described air-fuel ratio smoothing process is performed. FIG. 3 shows the influence of the torque change due to the air-fuel ratio smoothing process. T1 shows the target torque calculated last time, and T2 shows the target torque calculated this time.
Or, it shows the torque change when the above-mentioned smoothing process is not performed, and shows the torque change when the above-mentioned smoothing process is performed. As shown in FIG. 3, by performing the air-fuel ratio smoothing process, the torque change at that time can be brought close to the ideal torque change indicated by the solid line, and the occurrence of the shock can be prevented.

[0012]

According to the present invention, by using the target torque as the parameter for determining the air-fuel ratio, more precise air-fuel ratio control can be performed and the shock due to the torque step when the air amount changes can be reduced. be able to.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a device of the present invention.

FIG. 2 is a flowchart illustrating a processing procedure performed by an engine control computer shown in FIG.

FIG. 3 is a diagram showing an influence of a torque change due to an air-fuel ratio smoothing process.

FIG. 4 is a diagram illustrating a mutual relationship between an accelerator opening, an engine speed, and a target torque.

Claims (1)

[Claims] 1. A fuel injection control device for an engine, comprising means for calculating an air-fuel ratio based on a target torque obtained from an accelerator opening and an engine speed.