JPH0321736B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an electronically controlled fuel injection device for internal combustion engine pipes.

<Prior Art> A conventional example of an electronically controlled fuel injection device for an internal combustion engine is as shown in FIG. 3, for example.

a throttle sensor 4 that detects the opening degree of a throttle valve 3 interposed in an intake passage 2 of the internal combustion engine 1;
A rotation speed sensor 5 such as a crank angle sensor for detecting the engine rotation speed is provided, and these sensors 4,
Each detection signal from 5 is input to a control unit 6. The ROM of the microcomputer built in the control unit 6 has a ROM installed in the intake passage 2 corresponding to each operating range, which is divided into multiple operating ranges using the throttle valve opening and engine speed as parameters. A basic fuel injection amount Tp of fuel injected from the electromagnetic fuel injection valve 7 is stored.

Then, data on the basic fuel injection amount Tp in the corresponding operating range is searched from the map of the basic fuel injection amount Tp stored in the ROM according to the detected values of the throttle valve opening degree and the engine speed, and this data is used. A final fuel injection amount Ti is set by correcting it based on the engine cooling water temperature, etc., and an injection pulse signal corresponding to this fuel injection amount Ti is output to the fuel injection valve 7, causing the fuel injection valve 7 to adjust to the fuel injection amount. By opening the fuel injection valve 7 for a time corresponding to Ti, an amount of fuel corresponding to the fuel injection amount Ti is injected into the engine 1 from this fuel injection valve 7.
We are trying to supply it to

<Problems to be Solved by the Invention> Incidentally, as shown in FIG. It has the characteristic that it is easy to occur. Therefore, in such a low injection amount region, even if an injection pulse signal corresponding to the set fuel injection amount Ti is output to the fuel injection valve, the amount of fuel actually supplied to the engine from the fuel injection valve is less than the desired amount. It can be more or less. However, since the actual injection amount variation characteristics with respect to the injection pulse signal are approximately constant for each fuel injection valve, a certain fuel injection amount Ti
is set, the amount of fuel supplied from the fuel injection valve is less than the desired amount (e.g. point b in Fig. 4) or more than the desired amount (e.g. point b in Fig. 4).
The air-fuel ratio was maintained at point a) in the figure, and there was a risk that the air-fuel ratio would become over-lean or over-rich.

In particular, when setting the basic fuel injection amount Tp according to the detected values of the throttle valve opening and the engine speed, the fuel injection amount set during steady operation, such as in an idling state, becomes approximately constant, which causes the above problem. is likely to occur. This is because the basic fuel injection amount Tp (or intake air flow rate Q) is stored for each of multiple operating ranges in which the throttle valve opening and engine rotational speed are parameters. Compared to the case where the basic fuel injection amount Tp is calculated and set based on the detected value, the fuel injection amount is set in stages. It is for the sake of

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 avoid overrich or overlean air-fuel ratios due to variations in the injection amount of fuel injection valves.

<Means for Solving the Problems> Therefore, in the present invention, in an electronically controlled fuel injection device for an internal combustion engine equipped with a fuel injection valve in which the fuel injection amount is controlled through the injection time, as shown in FIG. a fuel injection amount setting means for setting a fuel injection amount based on the engine operating state detected by the engine operating state detecting means; a correction determining means that determines that correction is necessary when the injection amount is continuously substantially the same below the minimum fuel injection amount for which linearity of the injection amount with respect to the injection time of the valve is guaranteed; and the correction determining means determines that the correction is necessary. When the fuel injection amount is set by the fuel injection amount setting means, the fuel injection amount set by the fuel injection amount setting means is alternately increased by a predetermined amount and correction is decreased. a fuel injection amount increase/decrease correction means for periodically changing the injection amount; and a fuel injection valve according to the fuel injection amount set by the fuel injection amount setting means or the fuel injection amount corrected by the fuel injection amount increase/decrease correction means. and a drive control means for controlling the opening/closing drive of the electronically controlled fuel injection device.

<Function> According to this electronically controlled fuel injection device, the fuel injection amount set based on the engine operating state is less than or equal to the minimum fuel injection amount that guarantees linearity between the injection time and the injection amount in the fuel injection valve. When substantially the same injection amount continues in the non-linear region, corrections that increase the fuel injection amount by a preset amount and corrections that decrease the fuel injection amount are alternately and repeatedly applied, and the corrected fuel injection amount is It is made to change periodically in the non-linearity region of the fuel injector. With this correction, it is possible to avoid continuous injection based on a fixed injection amount in the non-linear region, and the average level of the injection amount after the increase correction and the injection amount after the decrease correction is adjusted according to the operating condition. It becomes possible to obtain an actual injection amount close to the desired amount.

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

However, since the hardware configuration is the same as the conventional example shown in FIG. 3, the same reference numerals will be used for explanation.

That is, in this embodiment, the control unit 6 controls the throttle valve opening α as the engine operating state.
The data of the basic fuel injection amount Tp retrieved based on the detected values of and the engine rotational speed N are determined in a predetermined region (0<Tp<Tp ₁ in Fig. 4) where variation in the injection amount of the fuel injector 7 occurs. When the basic fuel injection amount Tp is continuously the same in the
The control unit 6 also serves as fuel injection amount setting means, correction determining means, fuel injection amount increase/decrease correction means, and drive control means. Further, the throttle sensor 4 and the rotational speed sensor 5 correspond to the engine operating state detection means.

This increase/decrease correction of the basic fuel injection amount Tp will be explained based on the flowchart of FIG. 2.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the opening degree α of the throttle valve 3 detected by the throttle sensor 4 and the engine rotation speed detected by the rotation speed sensor 5 are determined. Read N.

In step 2, the basic fuel injection amount for the corresponding operating range is determined from the map of the basic fuel injection amount Tp stored in the ROM of the control unit 6 according to the throttle valve opening α and engine speed N read in step 1. Search Tp data.

In step 3, the basic fuel injection amount Tp retrieved and determined in step 2 is stored.

In step 4, it is determined whether the basic fuel injection amount Tp retrieved in step 2 is within the increase/decrease correction range (0<Tp<Tp ₁ ). As shown in FIG. 4, this increase/decrease correction range is a low injection amount region where the linearity of the actual injection amount with respect to the width (injection time) of the injection pulse signal to the fuel injector 7 is impaired (linearity is guaranteed). If the fuel injection valve 7 is continuously controlled based on the injection amount within this range ( _non -linearity region),
If the actual injection amount continues to be larger or smaller than the set injection amount, there is a risk that the air-fuel ratio will be large and off target.

Here, if it is determined that it is within the increase/decrease correction range, proceed to the next step 5, and if it is determined that it is not within the increase/decrease correction range, proceed to step 11 to determine the fuel injection amount based on the search value in step 2. Configure Ti settings.

In step 5, the basic fuel injection amount Tp currently retrieved in step 2 is compared with the previous basic fuel injection amount Tp (previous value) retrieved in the previous step 2 and stored in step 3. Here, if the previous value and the current search result match, proceed to step 6.
If it is not constant, proceed to step 11.

When proceeding from step 5 to step 6, that is, when the same basic fuel injection amount Tp within the increase/decrease correction range (non-linearity region of the fuel injection valve 7) is continuously searched, the flag is set in step 6. After making the determination, the basic fuel injection amount Tp searched in step 2
Make corrections to increase or decrease the amount.

If it is determined in step 6 that the flag is 0, the process proceeds to step 7, where a predetermined minute fuel injection amount △Tp set in advance is added to the basic fuel injection amount Tp retrieved in step 2, and the final value is calculated. Let the basic fuel injection amount be Tp. After performing the increase correction of the basic fuel injection amount Tp, the flag is set to 1 in step 8, and steps 6 to 9 are executed next time.
Let's move on to.

On the other hand, if it is determined in step 6 that the flag is 1, proceed to step 9 and subtract the above △Tp from the basic fuel injection amount Tp retrieved in step 2 to obtain the final basic fuel injection amount Tp. . After performing the reduction correction of the basic fuel injection amount Tp,
At step 10, the flag is set to 0 so that the next time the process proceeds from step 6 to step 7.

In this way, the same basic fuel injection amount Tp is continuously searched in step 2, and if the basic fuel injection amount Tp is in the non-linear region of the fuel injection valve 7, the search is performed. By alternately increasing and decreasing the basic fuel injection amount Tp, it is possible to avoid driving the fuel injection valve 7 from being continuously controlled based on the same basic fuel injection amount Tp in the nonlinear region.

Therefore, as shown in FIG. 4, even if the basic fuel injection amount Tp, at which a larger amount of fuel is actually supplied than the desired amount, is continuously searched, for example at point a, Since the basic fuel injection amount Tp changes in a non-linear region within a predetermined range (±△Tp),
By appropriately setting ΔTp for the increase/decrease correction, it is possible to obtain a fuel injection amount close to the desired amount.

That is, since point a is the peak of the variation in the injection amount (the difference from the desired amount is the largest on the increasing side), if the fuel injection valve 7 is continuously driven and controlled with the fuel injection amount at this point a, More fuel than the desired amount is continuously supplied, and overriching of the air-fuel ratio is unavoidable, but as the distance from point a increases, the actual fuel injection amount approaches the desired amount. Basic fuel injection amount in a predetermined minute range (±△T) centered on a point
By changing Tp, fuel injection control will be performed at a value closer to the desired amount than in the case of continuous control at least at point a. The same can be said of the control at point b, where the difference from the desired amount is greatest on the decreasing side.

Furthermore, if the basic fuel injection amount Tp in the search result is an intermediate point between point a and point b, the actual fuel injection amount at this point is close to the desired value, but the basic fuel injection amount is within the predetermined range. By changing the fuel injection amount Tp, it is possible to supply the engine with fuel close to the desired amount as an average level by repeating injections of more fuel and less fuel than the desired amount.

The basic fuel injection amount Tp searched in step 2,
Alternatively, the basic fuel injection amount Tp that has been increased or decreased in step 7 or step 9 is corrected in step 11 to set the final fuel injection amount Ti. That is, it is obtained by searching for correction coefficients based on each operating state stored in the ROM of the microcomputer of the control unit 6 from various operating states such as cooling water temperature and engine acceleration state, and calculating these correction coefficients. Various correction coefficients
The basic fuel injection amount Tp is corrected using COEF or the like to set the fuel injection amount Ti (Ti=Tp×COEF...).

When the fuel injection amount Ti is set in step 11, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is outputted to the fuel injection valve 7 in step 12 to cause fuel injection to be performed.

<Effects of the Invention> As explained above, according to the present invention, in the non-linear region below a predetermined injection amount where variation in the injection amount of the fuel injection valve occurs, the fuel injection valve is continuously operated based on the same fuel injection amount. The amount of fuel supplied to the engine can be brought close to the desired amount and the air-fuel ratio can be prevented from becoming overrich or overlean.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a flowchart showing a fuel injection amount control routine of an embodiment of the present invention, and Fig. 3 is a system showing a hardware configuration common to the above embodiment and the conventional example. FIG. 4 is a graph showing the nonlinear region of the fuel injection valve based on the relationship between the injection time (width of the injection pulse signal) and the actual injection amount in the fuel injection valve. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake passage, 3... Throttle valve, 4... Throttle sensor, 5... Rotational speed sensor, 6... Control unit, 7... Fuel injection valve.

Claims (1)

[Scope of Claims] 1. An electronically controlled fuel injection device for an internal combustion engine equipped with a fuel injection valve in which the fuel injection amount is controlled via injection time, the engine operation detected by an engine operation state detection means. A fuel injection amount setting means for setting the fuel injection amount based on a state, and linearity of the fuel injection amount set by the fuel injection amount setting means with respect to an injection time of the fuel injection valve is guaranteed. a correction determining means that determines that a correction is necessary when the minimum fuel injection amount is continuously equal to or less than the minimum fuel injection amount; Fuel injection amount increase/decrease correction means for periodically changing the fuel injection amount in a non-linear region of the fuel injection valve by alternately repeating correction for increasing the fuel injection amount by a predetermined amount and correction for decreasing the fuel injection amount by a predetermined amount. and a drive control means for controlling the opening and closing of the fuel injection valve according to the fuel injection amount set by the fuel injection amount setting means or the fuel injection amount corrected by the fuel injection amount increase/decrease correction means. Electronically controlled fuel injection system for internal combustion engines.