JPS6085238A - Electronic fuel injection device for engine - Google Patents

Abstract

PURPOSE:To exactly control an amount of injection fuel according to change in an actual amount of suction air at acceleration in an engine for an automobile, by correcting a fundamental amount of injection fuel according to acceleration of change in a suction air amount signal from an air flow sensor. CONSTITUTION:At acceleration, a suction air amount signal from an air flow sensor 13 is changed into velocity of change by a first differentiating circuit 23 of a control unit 12, and is further changed into acceleration of change by a second differentiating circuit 24. Then, increment to be corrected is computed by a correction signal generating circuit 25. Further, a fundamental amount of injection fuel is obtained by an operating circuit 21 in receipt of the suction air amount signal from the air flow sensor 13 and an engine rotational speed signal from a sensor 6. Then, the increment from the circuit 25 is multiplied to the fundamental amount of injection fuel by a correcting circuit 26, and a fuel injection valve 9 is controlled by a drive pulse from a drive pulse generating circuit 27. Thus, it is possible to prevent an air-fuel ratio from being made lean at an initial stage of acceleration and being made rich at a terminal stage of acceleration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic fuel injection device for an engine that controls the amount of fuel injection in response to an intake air amount signal from an air flow sensor that responds to the amount of intake air flowing through an intake passage. It is something.

(Prior art) Conventionally, engine electronic fuel controls the fuel injection amount according to the intake air amount signal from an air flow sensor that responds to the amount of air flowing through the intake passage, and also corrects the fuel injection amount during acceleration. Injection devices are known.

As such a device, for example, Utility Model Application No. 53-G/,!
There is one described in Publication No. 23, but since the rate of change of the intake air amount signal from the air amount meter is detected and the fuel injection amount is corrected accordingly, the method shown in Fig. 7 (a) As shown, the output of the airflow sensor (see broken line) and the actual intake air amount (see solid line) do not match. That is, at the beginning of acceleration, when the throttle valve is opened, air immediately flows between the air flow sensor and the throttle valve, but the subsequent air rotates with a delay due to the weight of the measuring member of the air flow sensor. Because it does not flow immediately from
While the intake air amount is incorrectly detected and the output of the airflow sensor becomes smaller than the actual intake air amount, at the end of the acceleration period, the intake air amount is limited by the throttle valve, but the above-mentioned metering member It moves due to inertia and overshoots, causing the output of the air flow sensor to be larger than the actual amount of intake air.

As a result, the intake air amount is detected to be small at the beginning of acceleration, so the fuel injection amount is smaller than the actually required amount and the air-fuel ratio is large and lean, and the intake air amount is detected at the end of acceleration. Since a large amount of fuel is detected, the amount of fuel injected is larger than the amount actually required, and the air-fuel ratio is small and rich, resulting in a problem that accurate control cannot be performed according to the actual amount of intake air.

(Object of the Invention) The present invention has been made in view of the above points, and by detecting the change acceleration of the intake air amount signal from the air flow sensor and determining the acceleration state of the engine, during acceleration,
It is an object of the present invention to provide an electronic fuel injection device for an engine that can accurately control a fuel injection amount according to an actual intake air amount.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention includes an air flow sensor that is disposed in an intake passage upstream of a throttle valve and responds to the amount of intake air flowing through the intake passage, and an intake air amount signal from the air flow sensor. basic fuel injection amount calculation means for calculating the basic fuel injection amount according to the change in the intake air amount signal; change acceleration detection means for detecting the change acceleration of the intake air amount signal from the air flow sensor; and correction of the basic fuel injection amount according to the change acceleration. The present invention is characterized by comprising a correction amount creation means for calculating the amount, and a correction means for correcting the basic fuel injection amount based on the correction amount. That is, the correction amount for the basic fuel injection amount is changed in accordance with the change acceleration obtained by differentiating the change rate of the intake air amount signal from the air flow sensor.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

In Fig. 1, 1 is an engine body, and an air cleaner 4, an air cleaner 4,
An air flow sensor 6 having a rotatable metering member 5 that responds to the amount of intake air, a throttle valve 7, a surge tank 8, and a fuel injection valve 9 are arranged in this order.

10 is an exhaust passage, and a catalyst device 11 (three-way catalyst) is disposed in the middle.

12 is a control unit consisting of a microcomputer;
The fuel injection amount of the fuel injection valve 9 is controlled by signals from the air flow sensor 6 and the rotation speed sensor 13.

14 is a spark plug, and 15 is an intake valve.

The control unit 12, as shown in detail in FIG.
A basic fuel injection amount calculation circuit 21 that calculates the basic fuel injection amount based on the intake air amount and engine speed, and an air flow sensor 6
The first and second differentiating circuits 23 and 2 constitute the change acceleration detection circuit 22 that detects the change acceleration of the intake air amount signal.
4. Correction (increase) signal generation circuit 25 as correction amount creation means for calculating a correction amount for the basic fuel injection amount according to the output signal (change acceleration signal) of the change acceleration detection circuit 22
, a correction circuit 26 that corrects the basic fuel injection amount based on the correction amount, and a drive pulse that outputs a drive pulse to the fuel injection valve 9 according to the corrected fuel injection amount that is the output of the correction circuit 26. It has a generating circuit 27.

With the above configuration, basically, the basic fuel injection amount calculation circuit 21 calculates the basic fuel injection amount based on the intake air amount signal from the air flow sensor 6 and the rotation signal from the rotation speed sensor 16. A drive pulse corresponding to this is generated in the drive pulse generation circuit 27, and the fuel injection valve 9 is driven based on this drive pulse.

On the other hand, during acceleration, the intake air amount signal from the air flow sensor 6 is first differentiated in the first differentiation circuit 26, and the rate of change in the intake air amount is output (see Figure 3 (C)).
. Next, the change rate signal that is the output of the first differentiator 23 is differentiated in the second differentiator 24, and the change acceleration that is the rate of change of the change rate of the intake air amount is output (see Fig.
c). However, number one! Based on the change acceleration signal that is the output of the differentiating circuit 24, a correction amount as a correction coefficient is calculated in the correction (increase) signal generation circuit 25 (see Fig. 3), and a correction signal (see Fig. 7 (b)) is calculated. ) is output to the complementary iE circuit 26. Therefore, when the rate of change in the speed of change is large, that is, when the acceleration of change is large, the correction signal is made large, and when the acceleration of change is small, the correction signal is made small. In the correction circuit 26, the basic fuel injection amount is multiplied by a correction coefficient (correction signal) to correct the fuel injection amount according to the acceleration state.The drive pulse generation circuit 27 generates a drive pulse based on the corrected fuel injection amount. is generated and controls the fuel injection valve 9.

Although the embodiments have been described above, the present invention also includes the case where a digital computer is used as the control unit 12.

(Effects of the Invention) The present invention corrects the basic fuel injection amount according to the change acceleration of the intake air amount signal from the air flow sensor, like a discharge record, so that when accelerating, the basic fuel injection amount is corrected according to the change in the actual intake air amount. Correspondingly, the fuel injection amount can be controlled accurately, and it is possible to prevent the air-fuel ratio from becoming IJ-rich at the beginning of acceleration or from becoming rich at the end of acceleration, which would occur if the fuel injection amount was controlled according to the rate of change of the intake air amount signal. .

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an engine fuel injection system according to an embodiment of the present invention, Fig. 2 is a block diagram showing an example of a control unit, and Fig. 3 is a block diagram showing an example of a control unit. Diagrams showing the relationship between the output of the differentiating circuit and the correction (increase) signal, Fig. 7 (a) (b) (
c) (b) is a diagram showing changes in the intake air amount, the first differentiation circuit output, the second differentiation circuit output, and the correction (increase) signal over time; 1... Engine body, 3... Intake passage, 6... Old air flow sensor, 7... Throttle valve, 9... Fuel injection valve, 12・・・・・・
Control unit, 21 Basic fuel injection amount calculation circuit, 22 Old... Change acceleration detection circuit, 25 Old...
・Correction (increase) signal generation port dδ, 26...Correction circuit

Claims (1)

[Claims] (1) "Throttle valve" An air flow sensor that is disposed in a second-stream intake passage and responds to the amount of intake air flowing through the intake passage, and a basic fuel injection amount that calculates the basic fuel injection amount according to the intake air amount signal from the air flow sensor. a calculation means, a change acceleration detection means for detecting the change acceleration of the intake air amount signal from the air flow sensor, a correction amount creation means for calculating a correction amount of the basic fuel injection amount according to the change acceleration, and the basic fuel injection amount. An electronic fuel injection device for an engine, comprising: a correction means for correcting the amount based on the correction amount.