JPS62258143A - Electronic control fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To set a fuel injection amount responding to an actual intake air flow rate and to prevent production of a fluctuation in an air-fuel ratio, by a method wherein, during elapse of a given time after the acceelration state of an internal combustion engine is detected, based on the detecting values of the opening of a throttle valve and the rotation speed of the engine, a fuel injection amount is set. CONSTITUTION:Means 2-5, detecting the acceleration state of an engine 1, an intake air flow rate, the opening of a throttle valve, and a rotation speed, respectively, are provided. A means 6 is provided for setting a fuel injection amount based on the detecting values of the opening of the throttle valve and the rotation speed of the engine only during elapse of a given time after the acceleration state of the engine 1 is detected. A means 7 is provided for setting a fuel injection amount based on the detecting values of the intake air flow rate and the rotation speed of the engine in a running region except a fuel injection amount set running region set by the means 6. Further, a means 8 is provided for driving and controlling a fuel injection valve 9 according to a fuel injection amount set by the means 6 and 7. This constitution sets a fuel injection amount responding to an actual intake air flow rate during acceleration of the engine.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electronically controlled fuel injection system for an internal combustion engine.

<Prior Art> Examples of conventional electronically controlled fuel injection devices for internal combustion engines include the following.

That is, from the intake air flow rate Q detected by the air flow meter and the engine rotational speed N detected from the ignition signal, etc., the basic fuel injection amount Tp (=KXQ/N; After calculating various correction coefficients C0EF according to engine operating conditions such as engine cooling water temperature, air-fuel ratio feedback correction coefficient α, and correction numerator s based on battery voltage, fuel injection 1i
Calculate Ti(-TpXCOEFXcr+Ts).

Then, an injection pulse signal having a pulse width corresponding to the calculated fuel injection amount Ti is outputted to the fuel injection valve to inject and supply a predetermined amount of fuel to the engine.

<Problems to be Solved by the Invention> By the way, according to such a conventional electronically controlled fuel injection system, there is a delay in response and control of the intake air flow rate detected by the air flow meter when the engine accelerates. As the error due to the calculation delay of the 11th gear increases, the air-fuel ratio becomes over lean, resulting in acceleration shock.

Output response delay (hesitation), deterioration of exhaust properties (N
There was a distortion that caused such things as an increase in Ox.

In addition, in the case of a multi-injection system, since the air flow meter is located upstream of the throttle valve, it will detect the intake manifold filling bone, and if the fuel injection is performed in accordance with this, it will be higher than the actual intake air flow rate. Fuel corresponding to the intake air flow rate is supplied,
The air-fuel ratio became over-rich, resulting in suffocation, wetting of the ignition plug, and deterioration of exhaust properties (increase in Co and HC).

That is, as shown in FIG. 4, in the early stages of acceleration, there is a delay in the detection response of the air flow meter to an increase in the intake air flow rate, so that an amount smaller than the actual intake air flow rate is detected. In addition, when the throttle valve is opened, air is sucked in by the negative and positive inside the intake manifold, and the inside of the intake manifold is filled with air before being sucked into the cylinder, but this air filling the intake manifold is also detected. An amount larger than the actual intake air flow rate (air sucked into the cylinder) will be detected.

In this way, if the intake air flow rate detected by the air flow meter is higher or lower than the actual amount, the fuel injection amount is set based on this intake air flow rate. Too little or too much fuel is injected and the air-fuel ratio becomes over-lean and over-rich alternately, and this has traditionally caused misfires during acceleration, causing acceleration shock, etc. It is something.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an electronically controlled fuel injection device that can set a fuel injection amount in accordance with the actual intake air flow rate during engine acceleration.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. means for detecting the opening degree of the installed throttle valve and the engine rotational speed, that is, an intake air flow rate detection means, a throttle valve distance detection means, an engine rotational speed detection means, and a predetermined period of time after the acceleration state of the engine is detected. Acceleration fuel injection amount setting means for setting the fuel injection amount based on the detected values of the throttle valve opening degree and engine rotational speed by the detection means, and a fuel injection amount setting operation range other than the fuel injection amount setting means by the acceleration fuel injection amount setting means. main fuel injection amount setting means for setting the fuel injection amount based on the detected values of the intake air flow rate and engine rotational speed by the detection means in the operating region; and the main fuel injection amount setting means or the acceleration fuel injection amount. The electronically controlled fuel injection device is configured to include a drive control means for driving and controlling the fuel injection valve according to the fuel injection amount set by the setting means.

According to the electronically controlled fuel injection device having such a configuration, the fuel injection amount is determined based on the detected values of the throttle valve opening and the engine rotational speed during acceleration when the intake air flow rate detection means has a large detection error of the intake air flow rate. Setting (acceleration fuel injection amount setting means) is performed.

Here, if you memorize the actual intake air flow rate or the basic fuel injection amount which is the engine required value (both are confirmed and set in advance through experiments etc.) according to the throttle valve opening and engine speed, The intake manifold filling bone is not included in the setting of the fuel injection amount, and there is no response delay in detecting the throttle valve opening and engine rotation speed. Since the fuel injection amount is not set based on the fuel injection amount, it is possible to prevent the air-fuel ratio from becoming over-lean or over-rich during acceleration.

On the other hand, for a predetermined period of time after acceleration is detected, the fuel injection amount is set based on the detected values of the throttle valve opening and engine speed as described above (acceleration fuel injection amount setting means).
However, in other operating ranges, the fuel injection amount is set (main fuel injection amount setting means) based on the detected values of the intake air flow rate and the engine rotational speed.

This is because the detected value of the intake air flow rate is accurate at times other than acceleration, and can also respond to changes in air density, etc., so fuel injection is performed based on the detected value of the intake air meteor at times other than acceleration. This allows you to set the amount.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 2 shows the configuration of an embodiment of an electronically controlled fuel injection device according to the present invention.

In this figure, the engine rotation speed signal N is the output of the rotation speed sensor 1 as the engine rotation speed detection means, the intake air flow rate signal Q is the output of the air flow meter 2 as the intake air flow rate detection means, and the throttle valve opening detection The opening signal α of a throttle valve (not shown) installed in the intake passage of the engine is the output of the throttle valve opening sensor 3 as a means.
and the engine cooling water temperature signal T which is the output of the water temperature sensor 4.
w is input to a control unit 5 that includes a built-in microcomputer constituted by an input/output device, a storage device, and a central processing unit, and the control unit 5 generates an injection pulse signal that is set as described below based on these signals. It is output to the drive circuit 6 of the fuel injection valve 7.

That is, in this embodiment, the control unit 5:
The throttle valve opening sensor 3 constitutes an engine acceleration state detection means, and the drive circuit 6 constitutes a drive control means, while the acceleration fuel injection amount setting means and the main fuel injection amount setting means are configured by software. We are prepared.

Next, the operation will be explained based on the flowchart shown in FIG.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the engine rotation speed N detected by each sensor is
, intake air flow rate Q, throttle valve opening α, and cooling water temperature Tw are input.

In step 2, it is determined whether the engine is in an accelerating state based on the opening change rate Δα obtained from the throttle valve opening α input in step 1 and the throttle valve opening α input last time. That is, when Δα shows a rate of change toward the open side of a predetermined rate or more, the engine is determined to be in an accelerating state, and the process proceeds to step 3.

In step 3, the intake air flow rate Qs, which has been stored in advance in association with a plurality of operating ranges in which the throttle valve opening degree α and the engine speed N are parameters, is transferred to the throttle valve opening degree α input in step 1 and Search based on engine rotation speed N. Here, the intake air flow i is stored using the throttle valve opening α and the engine speed N as parameters.
Qs has been determined in advance through experiments, etc., and is close to the actual value, which does not include intake manifold filling and the like. In addition, when obtaining the intake air flow IQs by searching as described above, it is based on the throttle valve opening α and the engine speed N, which are the triggers for changes in the intake air flow rate, so there is almost no response delay in detection. Good to say.

In step 4, the basic fuel injection amount Tp (=KXQs/
N; is a constant).

On the other hand, when it is determined in step 2 that the engine is not in an accelerating state, it is determined in step 5 whether or not the elapsed time from the first detection of acceleration is within a predetermined time TI (for example, 1 second). Here, the predetermined time TI is approximately equal to the time it takes for air to be filled into the intake manifold when the throttle valve is opened from an idle state. Therefore, when the elapsed time is within the predetermined time Tl, it is estimated that the intake airflow IQ detected by the airflow meter 2 has a large error. Therefore, when it is determined in step 5 that the elapsed time is within the predetermined time Ti, the process proceeds to steps 3 and 4, and the intake air flow rate is retrieved in the same way as when it is determined that the engine is in an accelerating state in step 2. The basic fuel injection amount Tp is calculated based on Qs.

Further, when it is determined in step 5 that the predetermined time T1 or more has elapsed, that is, when the engine is not in an acceleration state but the predetermined time T has elapsed since acceleration, the process proceeds to step 6 and the input is input in step 1. The basic fuel injection amount T is based on the detected value of the air flow meter 2 (intake air flow rate Q).
p (=KXQ/N; K is a constant) is calculated. In this operating region, as shown in FIG. 4, the intake manifold filling bone is not detected, so the intake air flow rate Q detected by the air flow meter 2 is approximately the same.

Basic fuel injection f in step 4 or step 6
After the calculation setting of f1Tp is made, in step 7, the basic fuel injection ff1Tp is corrected and calculated to obtain the final fuel injection l T i .

That is, the cooling water temperature Tw detected by the water temperature sensor 4
Based on the various operating conditions such as engine speed and engine acceleration, correction coefficients based on each operating condition stored and set in the storage device are searched, and these correction coefficients are calculated by the central processing unit. A fuel injection amount Ti is set by correcting the basic fuel injection amount Tp.

When the fuel injection lTi is set in step 7, in step 8, an injection pulse signal with a pulse width corresponding to j [l is output to the drive circuit 6 of the fuel injection valve 7 to perform fuel injection. .

In this way, during acceleration where the air flow meter 2 has a large detection error (in a state where acceleration is being detected or within a predetermined time T+ from acceleration detection), the throttle valve opening α and engine rotation speed N, which have relatively small errors, are adjusted. Since the basic fuel injection amount 'rp is set based on the intake air flow IQs retrieved based on the intake air flow IQs, the fuel injection amount is set in accordance with the actual intake air flow rate, and the air-fuel ratio is prevented from becoming over-rich or over-lean. can be prevented.

In addition, in operating regions where the air flow meter 2 detection error is small (other than during acceleration), the basic fuel injection NTp is set based on the detected value of the air flow meter 2, so even if there is a change in air density, etc., the actual The intake air flow rate is detected, and fuel injection is performed in accordance with the engine's required value.

<Effects of the Invention> As explained above, according to the present invention, the fuel injection amount is set based on the detected values of the throttle valve opening and the engine rotational speed for a predetermined period of time after acceleration detection. In such an operating region where the detection error by the flow rate detection means is large, the fuel injection amount is set in accordance with the actual intake air flow rate, and it is possible to prevent the air-fuel ratio from becoming over-rich or over-lean during acceleration.

Therefore, the occurrence of misfire during acceleration is suppressed, and there is an effect that it is possible to prevent the occurrence of acceleration shock, breathing, deterioration of exhaust characteristics, etc.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a system diagram showing an embodiment of an electronically controlled fuel injection device according to the present invention, FIG. 3 is a flowchart showing fuel injection amount setting control in the above embodiment, and FIG. FIG. 4 is a time chart for explaining problems in conventional control. 1... Rotation speed sensor 2... Air flow meter 3... Throttle valve opening sensor 4... Water temperature sensor 5... Control unit 6... Drive circuit 7... Fuel injection valve

Claims (1)

[Claims] an engine acceleration state detection means for detecting an acceleration state of the engine; a means for detecting an intake air flow rate of the engine; an opening degree of a throttle valve installed in an intake passage of the engine; and an engine rotation speed; and an acceleration state of the engine. an acceleration fuel injection amount setting means for setting a fuel injection amount based on detected values of a throttle valve opening degree and an engine rotational speed for a predetermined period of time after the acceleration fuel injection amount setting means is detected; and a fuel injection amount setting means by the acceleration fuel injection amount setting means. main fuel injection amount setting means for setting the fuel injection amount based on detected values of intake air flow rate and engine rotational speed in an operating region other than the operating region; and the main fuel injection amount setting means or the acceleration fuel injection amount setting. An electronically controlled fuel injection device for an internal combustion engine, comprising: drive control means for driving and controlling a fuel injection valve according to a fuel injection amount set by the means.