JPH041179B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device 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 (=K×Q/ N; K is a constant), as well as various correction coefficients COEF according to engine operating conditions such as engine cooling water temperature, air-fuel ratio feedback correction coefficient α, and battery voltage correction Ts, and then calculate the fuel injection amount. Ti(=Tp
×COEF×α+Ts).

Then, an injection pulse signal with 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 (Japanese Patent Application Laid-Open No. 59-203828, etc. reference).

By the way, according to such an electronically controlled fuel injection system, as shown in FIG. 5, when the engine accelerates, a detection error occurs due to a delay in the response of the intake air flow rate detected by the air flow meter, detection of the intake manifold filling amount, etc. As a result, the fuel injection amount is set based on this incorrect intake air amount detection value, causing the air-fuel ratio to become over-lean or over-rich, causing acceleration shock, heavy breathing, and deterioration of exhaust properties. There was a fear that this would happen.

In order to solve this problem, the fuel injection amount (specifically, the basic fuel injection amount) is adjusted based on the throttle valve opening and engine rotational speed for a predetermined period of time after acceleration detection.
Tp and is shown as α-N control in FIG. ) There is an electronically controlled fuel injection device that allows the setting of

That is, the intake air flow rate Q or basic fuel injection amount Tp (these intake air flow rates Q or basic fuel The injection amount Tp is a value based on the actual intake air flow rate, which does not include intake manifold filling, etc., determined through experiments etc.) is stored, and the data is calculated based on the throttle valve opening α and engine speed. Based on the detected value of the speed N, data in a corresponding driving range is searched from among the data.

Then, when acceleration of the engine is detected by an idle switch or the like, the basic fuel injection amount Tp (α - N If the intake air flow rate Q is stored in the map, the searched Q
If the basic fuel injection amount Tp is calculated from the basic fuel injection amount Tp and the basic fuel injection amount Tp is stored, the basic fuel injection amount Tp is set by searching. ), and in the operating range other than this predetermined time, the basic fuel injection amount Tp (=
K×Q/N (K is a constant) is set.

<Problems to be Solved by the Invention> However, when the fuel injection amount is set based on the detected values of the throttle valve opening α and the engine speed N as described above, the throttle valve is bypassed. Since the air flow rate supplied by the engine is unrelated to the fuel injection amount setting, there is a risk that the fuel injection amount will be set to match the amount of air that is smaller than the actual intake air flow rate, causing the air-fuel ratio to become over-lean. It was hot.

That is, when controlling the idle rotation speed by controlling the opening and closing of the idle control valve installed in the auxiliary air passage that bypasses the throttle valve (depending on the engine temperature), or when increasing the intake air flow rate when the engine is cold ( Air that is not related to the throttle valve opening (increased in inverse proportion to the engine temperature represented by the cooling water temperature) may be supplied by bypassing the throttle valve. When air flowing through various bypass passages provided in Therefore, there is a shortage of fuel corresponding to the air flow rate that is supplied bypassing the throttle valve.

Furthermore, if the fuel injection amount is set based on the detected values of the throttle valve opening α and the engine speed N only during acceleration, the throttle valve is used to set the fuel injection amount during acceleration as described above. However, in the operating range where the fuel injection amount is set based on the detected value of the intake air flow rate Q, the air flow rate that bypasses the throttle valve is also included in the setting. The fuel injection amount set at the time of switching the means may show a stepwise sudden change. As described above, if the fuel injection amount changes rapidly, there is a risk that problems such as acceleration shock and deterioration of exhaust properties may occur.

The present invention has been made in view of the above problems, and is an electronically controlled fuel injection system in which the fuel injection amount is set based on the detected values of the throttle valve opening and the engine speed only during acceleration. The purpose is to enable fuel injection amount setting to be made in a manner that actually matches the intake air flow rate.

<Means for solving the problem> Therefore, in the present invention, as shown in FIG.
An engine acceleration state detection means for detecting the acceleration state of the engine, and a means for detecting the intake air flow rate of the engine, the opening degree of the throttle valve installed in the intake passage of the engine, the engine rotation speed, and the engine temperature, that is, the intake air flow rate. Fuel injection is performed based on the detection means, the throttle valve opening degree detection means, the engine rotational speed detection means, the engine temperature detection means, and the detected values of the throttle valve opening degree and the engine rotational speed for a predetermined time after the acceleration state of the engine is detected. acceleration fuel injection amount setting means for setting the amount of fuel injection for acceleration; bypass air flow rate calculation means for calculating the total flow rate of bypass air flowing through various bypass passages provided by bypassing the throttle valve according to the engine temperature; and the acceleration fuel injection amount. Acceleration fuel injection amount correction means for correcting the fuel injection amount set by the injection amount setting means in accordance with the bypass air flow rate calculated by the bypass air flow rate calculation means; and the acceleration fuel injection amount setting. a main fuel injection amount setting means for setting a fuel injection amount based on detected values of an intake air flow rate and an engine rotational speed in an operating region other than an operating region where the fuel injection amount is set by the means; and the acceleration fuel injection amount correction means. and drive control means for driving and controlling the fuel injection valve according to the fuel injection amount corrected by the above-mentioned fuel injection amount or the fuel injection amount set by the main fuel injection amount setting means, an electronically controlled fuel injection device is configured. I decided to do so.

<Function> According to the electronically controlled fuel injection device having such a configuration,
For a predetermined period of time after the acceleration state of the engine is detected, the fuel injection amount is set based on the detected values of the throttle valve opening and the engine rotation speed, and the fuel injection amount thus set is It is corrected according to the flow rate of bypass air supplied by bypassing the throttle valve, which is calculated according to the engine temperature represented by temperature.

In other words, the fuel injection amount, which is set based on the detected values of the throttle valve opening and engine rotational speed, does not include the air flow rate that is supplied by bypassing the throttle valve, so it varies depending on the engine temperature. By correcting the bypass air flow rate in accordance with the calculated bypass air flow rate in the operating state, the fuel injection amount can be set in accordance with the actual intake air flow rate.

<Example> An example 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 signal Q is the output of the air flow meter 2 as the intake air flow rate detection means, and the throttle valve opening. 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 detection means, and the engine's opening signal α is the output of the water temperature sensor 4 as an engine temperature detection means. The cooling water temperature signal Tw is input to the control unit 5 which has a built-in microcomputer constituted by an input/output device, a storage device, and a central processing unit, and the control unit 5 is set as described below based on these signals. It outputs an injection pulse signal to the drive circuit 6 of the fuel injection valve 7.

That is, in this embodiment, the control unit 5 constitutes engine acceleration state detection means with the throttle valve opening sensor 3, and constitutes drive control means with the drive circuit 6. The fuel injection amount setting means, the bypass air flow rate calculation means, the main fuel injection amount setting means, and the acceleration fuel injection amount correction means are provided as software.

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, intake air flow rate Q, throttle valve opening α, and cooling water temperature Tw detected by each sensor 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, it is determined that the engine is in an accelerating state, and the process proceeds to step 3.

In step 3, the intake air flow rate is stored in advance in correspondence to multiple operating ranges using the throttle valve opening α and engine speed N as parameters.
From the map of Qs (hereinafter referred to as α-N map),
The intake air flow rate Qs in the relevant operating region is searched based on the throttle valve opening α and engine rotational speed N input in step 1.

Here, throttle valve opening α and engine rotation speed N
and the intake air flow rate stored as parameters.
Qs is determined in advance through experiments and the like, and is approximated to an actual value that does not include intake manifold filling and the like. In addition, when obtaining the intake air flow rate Qs by searching as described above, the response delay in detection is almost negligible because it is based on the throttle valve opening α and the engine rotation speed N, which are the triggers for changes in the intake air flow rate. It's okay to say that there isn't.

In step 4, a corrected intake air flow rate Qt (bypass air flow rate) set and stored in advance is searched according to the cooling water temperature Tw. Here, the corrected intake air flow rate Qt is set to be inversely proportional to the cooling water temperature Tw, as shown in FIG. This is because the air amount for idle rotation speed control and air increase correction during cold operation are controlled to be approximately inversely proportional to the cooling temperature Tw, so this approximately matches the air flow rate that is supplied by bypassing these throttle valves. It is set in accordance with the cooling water temperature Tw so that Of course, the corrected air flow rate Qt may be calculated from the detected cooling water temperature Tw.

In step 5, the basic fuel injection amount Tp {=K
×(Qs+Qt)/N; K 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 6 whether or not the elapsed time from the first detection of acceleration is within a predetermined time (for example, 1 second). Here, the predetermined time is set to approximately match the time required for air filling into the intake manifold to be completed when the throttle valve is opened from an idle state.

Therefore, when the elapsed time is within this predetermined time, it is estimated that the intake air flow rate Q detected by the air flow meter 2 has a large error. Therefore, when it is determined in step 6 that the elapsed time is within the predetermined time, the process proceeds to steps 3 to 5.
The basic fuel injection amount Tp is calculated based on the retrieved intake air amount Qs and corrected intake air flow rate Qt in the same way as when it was determined in step 2 that the engine is in an accelerating state.

If it is determined in step 6 that the predetermined time has elapsed, the process proceeds to step 7 and the basic fuel injection amount Tp (=K xQ/N; K is a constant). In such an operating region, the intake air flow rate Q detected by the air flow meter 2 is approximately accurate because the intake manifold filling amount is not detected as shown in FIG.

In step 8, the basic fuel injection amount Tp set in step 5 or step 7 is corrected to determine the final fuel injection amount Ti. That is,
Cooling water temperature Tw detected by water temperature sensor 4
Various correction coefficients COEF, etc. are obtained by searching for correction coefficients based on each operating state stored and set in a storage device from various operating states such as engine speed and engine acceleration state, and calculating these correction coefficients with a central processing unit. A fuel injection amount Ti is set by correcting the basic fuel injection amount Tp.

When the fuel injection amount Ti is set in step 8, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is outputted to the drive circuit 6 of the fuel injection valve 7 in step 9 to cause fuel injection to be performed.

In this way, during acceleration with a large detection error by the air flow meter 2 (in a state where acceleration is being detected or within a predetermined period of time after acceleration detection), the throttle valve opening α and the engine rotation speed N, which have a relatively small detection error, can be adjusted. Intake air flow rate Qs searched based on
The basic fuel injection amount Tp is set by the corrected intake air amount Qt (bypass air flow rate), which depends on the cooling water temperature Tw (engine temperature), and the air flow rate that is supplied by bypassing the throttle valve. The fuel injection amount is set based on the actual intake air flow rate including , the air-fuel ratio becomes over-lean due to a setting commensurate with an amount of air smaller than the actual intake air flow rate.

In addition, the basic fuel injection amount is determined based on the detected values of the throttle valve opening α and the engine speed N.
Since Tp is set in accordance with the actual intake air flow rate in the operating range where Tp is set, the basic fuel injection amount is determined based on the detected intake air flow rate Q.
In a transient state (when switching the basic fuel injection amount Tp setting means) with the operating region where Tp is achieved (the operating region where the detection error of the air flow meter 2 is small), the basic fuel injection amount Tp to be set In other words, the fuel injection amount Ti does not exhibit sudden changes, and it is possible to avoid misfires and acceleration shocks during such transitions.

<Effects of the Invention> As explained above, according to the present invention, the fuel injection amount that is set based on the detected values of the throttle valve opening and the engine rotational speed is changed from the throttle valve that is calculated according to the engine temperature. By making corrections according to the air flow rate supplied by bypass,
The fuel injection amount is set based on the intake air flow rate that is closer to the actual amount, and it is possible to prevent the air-fuel ratio from becoming overlean in the operating range (predetermined time from acceleration detection) by such setting means.

Furthermore, as mentioned above, in the operating range where the fuel injection amount is set based on the detected values of the throttle valve opening and the engine speed, the setting is made in accordance with the actual intake air flow rate, so the intake air flow rate and When switching between the case where the fuel injection amount is set based on the detected value with respect to the engine rotational speed, a large deviation in the set fuel injection amount is avoided, and there is also the effect that acceleration shock and the like can be prevented.

[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, and FIG. 3 is a flowchart showing fuel injection amount setting control in the same embodiment. Figure 4 shows the corrected intake air flow rate Qt and cooling water temperature Tw in the same example as above.
FIG. 5 is a time chart for explaining problems in conventional control. DESCRIPTION OF SYMBOLS 1...Rotational 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] 1 An engine acceleration state detection means for detecting the acceleration state of the engine; 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 for a predetermined period of time after the acceleration state of the throttle valve is detected; and various bypasses provided to bypass the throttle valve. bypass air flow rate calculation means for calculating the total flow rate of bypass air flowing through the passage according to engine temperature;
Acceleration fuel injection amount correction means for correcting the fuel injection amount set by the acceleration fuel injection amount setting means in accordance with the bypass air flow rate calculated by the bypass air flow rate calculation 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 fuel injection amount setting operation region by the amount setting means; and the acceleration fuel injection amount correction. drive control means for driving and controlling a fuel injection valve according to the fuel injection amount corrected by the means or the fuel injection amount set by the main fuel injection amount setting means; Control fuel injector.