JPH05288102A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress NOX emission while enhancing acceleration performance at the time of acceleration operation from the lean burn control region where air fuel ratio is less than theoretical air-fuel ratio. CONSTITUTION:When the timing of acceleration operation from the lean burn control region is detected (S1), an acceleration increment correction factor is retrieved from a map for having approximately a multiple of the theoretical air-fuel ratio with respect to a set air fuel ratio in lean burn controlling (S2), and with this correction factor, a fuel injection quantity in lean burn controlling is corrected (S4).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for an internal combustion engine, and more particularly to a device for controlling an air-fuel ratio to a predetermined air-fuel ratio leaner than a stoichiometric air-fuel ratio in a predetermined operating region.

[0002]

2. Description of the Related Art The following is a conventional example of a fuel supply system for an internal combustion engine of this type (Japanese Patent Laid-Open No. 63-105).
256, JP-A-60-135634, JP-A-60-135634
61-11440). That is, in a predetermined low speed and low load operation region where lean combustion is possible without requiring high output, the air-fuel ratio becomes a predetermined air-fuel ratio leaner than the theoretical air-fuel ratio (14.8) (for example, 22 to 25). The fuel injection amount is calculated and supplied to the engine (hereinafter referred to as lean control) to improve fuel efficiency and purify exhaust gas. Further, in the operating region other than the above, the fuel injection amount is calculated so that the air-fuel ratio becomes substantially the theoretical air-fuel ratio, and in the high-speed high-load operating region, the fuel injection is performed so that the air-fuel ratio becomes a predetermined air-fuel ratio which is richer than the theoretical air-fuel ratio. I am trying to calculate the amount.

When an acceleration operation is detected during lean control, the intake air amount detected by, for example, an air flow meter is added to the corrected intake air amount during acceleration to increase the fuel injection amount and enrich the air-fuel ratio. I am trying.

[0004]

By the way, as shown in FIG. 6, the NO _x emission amount has a characteristic that it increases as the air-fuel ratio becomes leaner than the stoichiometric air-fuel ratio and then decreases as it leans. In the region, the NO _X emission amount can be sufficiently reduced. However, by simply adding the acceleration correction intake air amount to the intake air amount during acceleration operation during the lean control so as to enrich the air-fuel ratio can be set the air-fuel ratio to an optimum value for reducing the NO _X Without N
O _X emissions there is a problem of increasing.

[0005] The present invention has been made in view of such circumstances, while improving the acceleration performance during acceleration operation NO _X
The purpose is to reduce the amount of emissions.

[0006]

Therefore, according to the present invention, as shown in FIG. 1, the fuel supply amount is set so that the actual air-fuel ratio becomes a set air-fuel ratio leaner than the stoichiometric air-fuel ratio in a predetermined lean control range. Which includes the fuel supply amount setting means A for setting the acceleration operation state detecting means B for detecting the acceleration operation state.
And a correction coefficient setting means C for setting an acceleration increase correction coefficient that is a multiple of the stoichiometric air-fuel ratio with respect to the set air-fuel ratio, and the fuel supply amount when the acceleration operation state from the lean control range is detected. A correction unit D for increasing the amount based on the acceleration amount increase correction coefficient, and a drive control unit F for driving and controlling the fuel supply unit E based on the corrected fuel supply amount are provided.

[0007]

In the acceleration operation from the lean control range, the fuel supply amount is corrected by the acceleration increase correction coefficient that is a multiple of the approximate stoichiometric air-fuel ratio with respect to the set air-fuel ratio during lean control. The air-fuel ratio of is controlled so as to be substantially the theoretical air-fuel ratio.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2, a control device 1 including a microcomputer includes a rotation speed sensor 2 that detects an engine rotation speed, an air flow meter 3 that detects an intake air amount, a water temperature sensor 4 that detects a cooling water temperature, and an exhaust gas. Detection signals are input from an oxygen sensor 5 that detects an air-fuel ratio from the oxygen concentration therein and a throttle sensor 6 that serves as an acceleration operating state detection unit that detects the throttle valve opening.

The control device 1 outputs an injection pulse signal to a fuel injection valve 7 as a fuel supply means via a drive circuit 8 to perform a fuel injection operation. here,
The control device 1 constitutes a fuel supply amount setting means, a correction coefficient setting means, and a correction means. In addition, the control device 1 and the drive circuit 8
And constitute drive control means. Next, the operation will be described with reference to the flowchart of FIG.

First, the lean control will be described. It is determined that the engine speed is within a predetermined range and the engine load such as the basic injection amount is within a predetermined range in a low speed low load operation region, and the cooling water temperature is a predetermined value (for example, 80 °). C) the vehicle speed is a predetermined value (for example, 8 km)
/ H) or more, it is determined that the lean control condition is satisfied. Then, when it is determined that the lean control condition is satisfied, the actual air-fuel ratio is leaner than the stoichiometric air-fuel ratio (for example, 20 to 25, and the engine rotation speed and the engine rotation speed are as shown in FIG. 4). And the basic injection amount are set according to the following equation, and the fuel injection valve 7 is driven through the drive circuit 8 based on the calculated fuel injection amount. Drive control.

Further, when the lean control condition is not satisfied, the fuel injection amount is calculated so that the air-fuel ratio becomes the stoichiometric air-fuel ratio (14.8), and the fuel injection valve 7 is drive-controlled based on the fuel injection amount. Further, in the high speed and high load region, the fuel injection amount is calculated so that the air-fuel ratio is higher than the theoretical air-fuel ratio. During the lean control, in S1 of FIG. 3, it is determined whether or not the acceleration operation is performed based on the opening change amount of the throttle valve detected by the throttle sensor 6. If YES, the process proceeds to S2, and if NO, the process proceeds to S3. ..

In S2, the acceleration increase correction coefficient K1 is searched from the map based on the detected engine speed and the basic injection amount calculated in the previous routine. As shown in FIG. 5, the acceleration amount increase correction coefficient K1 is set to be different for each region divided by the engine rotation speed and the basic injection amount. These acceleration increase correction coefficient K1 is set to a multiple of the theoretical air-fuel ratio with respect to the set air-fuel ratio.

At S3, various correction factors COEF mainly for water temperature correction are calculated. In S4, the fuel injection amount T _i is calculated by the following equation. T _i = T _p × COEF × LBC × K1 + TS T _p is a basic injection amount (= KQ / N, K is a constant) calculated from the engine speed N and the intake air amount Q, and LBC is the set air-fuel ratio or the theoretical value. An air-fuel ratio correction coefficient corresponding to the air-fuel ratio, TS is a correction amount by the battery voltage.

Then, based on the calculated fuel injection amount T _i , an injection pulse signal is output to the fuel injection valve 7 via the drive circuit 8 to supply fuel to the engine. As described above, during the acceleration operation from the lean control, the acceleration increase correction coefficient K1 set to a multiple of the theoretical air-fuel ratio with respect to the set air-fuel ratio.
Since the fuel injection amount is calculated by multiplying by the formula, the air-fuel ratio during acceleration operation can be maintained at a substantially stoichiometric air-fuel ratio, so the NO _X emission amount during acceleration operation can be greatly suppressed (see FIG. 6). ) And acceleration performance can be improved.

The acceleration increase correction coefficient may be introduced as a parameter of the various correction coefficients.

[0016]

As described above, according to the present invention, during the acceleration operation from the lean control range, the fuel supply amount is increased by the acceleration increase correction coefficient which is a multiple of the substantially theoretical air-fuel ratio with respect to the set air-fuel ratio during lean control. since was such that increasing correction, can maintain the air-fuel ratio at the time of acceleration operation from the lean control area to the stoichiometric air-fuel ratio, while improving the acceleration performance can be suppressed NO _x emissions amount.

[Brief description of drawings]

FIG. 1 is a diagram for responding to a claim of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

FIG. 3 Flowchart of the above

FIG. 4 is a diagram for explaining the operation of the above.

FIG. 5 is another diagram for explaining the operation of the above.

FIG. 6 is a diagram for explaining a conventional defect.

[Explanation of symbols]

 1 Control Device 2 Rotation Sensor 3 Air Flow Meter 6 Throttle Sensor 7 Fuel Injection Valve 8 Drive Circuit

Claims (1)

[Claims] 1. A fuel supply device for an internal combustion engine, comprising fuel supply amount setting means for setting a fuel supply amount such that an actual air-fuel ratio becomes a set air-fuel ratio leaner than a theoretical air-fuel ratio in a predetermined lean control range. Acceleration operating state detection means for detecting an acceleration operating state, correction coefficient setting means for setting an acceleration increase correction coefficient that is a multiple of a substantially stoichiometric air-fuel ratio with respect to the set air-fuel ratio, and acceleration operating state from the lean control range Correction means for increasing and correcting the fuel supply amount based on the acceleration increase correction coefficient when detected, and drive control means for driving and controlling the fuel supply means based on the corrected fuel supply amount. A fuel supply device for an internal combustion engine, comprising: