JPH0663464B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

<Prior Art> The following is a conventional example of an electronically controlled fuel injection device for an internal combustion engine.

That is, the basic fuel injection amount Tp (= K × Q / N) corresponding to the intake air amount per rotation is calculated from the intake air amount Q detected by the air flow meter and the engine rotation speed N detected from the ignition signal or the like. ; K is a constant) and various correction factors COEF according to engine operating conditions such as engine cooling water temperature
After calculating the air-fuel ratio feedback correction coefficient α and the correction amount Ts by the battery voltage, the fuel injection amount Ti (= Tp × COEF
× α × Ts) is calculated.

Then, an injection pulse signal having a pulse width corresponding to the calculated fuel injection amount Ti is output to the fuel injection valve to inject and supply a predetermined amount of fuel to the engine (Japanese Patent Laid-Open No. 59-2038).
No. 28, etc.).

By the way, according to such an electronically controlled fuel injection device, when the engine is accelerated, as shown in FIG. On the other hand, since the error becomes large, the fuel injection amount is set based on this erroneous detection value of the intake air flow rate, and over lean and over rich air-fuel ratios occur alternately, resulting in acceleration shock, breathing, and exhaust. There was a fear of causing deterioration of the property.

In order to solve such a problem, there is an electronically controlled fuel injection device in which the fuel injection amount is set based on the throttle valve opening and the engine rotation speed for a predetermined time from the acceleration detection.

That is, the intake air flow rate Q or the basic fuel injection amount Tp (the intake air flow rate Q or the basic fuel) corresponding to each operation region is set in advance for each of a plurality of operation regions using the throttle valve opening α and the engine speed N as parameters. The injection amount Tp is a value based on the actual intake air flow rate that does not include the intake manifold filling amount obtained by experiments, etc.), and the throttle valve opening α and the engine rotation speed N are stored.
Based on the detected value of, the data in the corresponding operating region is searched from the data.

When the acceleration of the engine is detected by the idle switch or the like, the basic fuel injection amount Tp (α-N map is set in the basic fuel injection amount Tp based on the detected values of the throttle valve opening α and the engine rotation speed N for a predetermined time after the acceleration is detected. When the intake air flow rate Q is stored, the basic fuel injection amount Tp is calculated from the retrieved Q, and when the basic fuel injection amount Tp is stored, the basic fuel injection amount Tp is set by the search.) Is set, and the basic fuel injection amount Tp (= K × Q / N) is set based on the detected values of the intake air flow rate Q and the engine speed N detected by the air flow meter in the operating region other than the predetermined time. To do so.

<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 only during acceleration as described above, At the time of switching to the fuel injection amount setting based on the detected value of the air amount Q, the fuel injection amount shows a stepwise rapid change due to the deviation of the set fuel injection amount, and the acceleration shock is generated due to the output difference due to the step of the mixture ratio. However, there is a fear that inconveniences such as exhaustion and deterioration of exhaust properties may occur.

The cause of the deviation of the set fuel injection amount is as follows.
When the fuel injection amount based on the detection values of the throttle valve opening α and the engine speed N and the fuel injection amount based on the detection values of the intake air flow rate Q and the engine speed N originally deviate, When air that bypasses the throttle valve, such as air from an air regulator, which is not related to the correlation between the valve opening α and the engine speed N, is sucked, the detection of the throttle valve opening α and the engine speed N is further performed. The fuel injection amount based on the value does not change with respect to the rich air density, whereas the air flow meter detects the intake air flow rate Q corresponding to the rich air density.

The present invention has been made in view of the above problems, and in an electronically controlled fuel injection device in which the fuel injection amount is set based on the detected values of the throttle valve opening and the engine rotation speed only during acceleration, It is an object of the present invention to prevent the fuel injection amount from abruptly changing stepwise when the setting means is switched.

<Means for Solving Problems> Therefore, in the present invention, as shown in FIG. 1, the engine acceleration state detecting means for detecting the acceleration state of the engine and the intake air for directly detecting the intake air flow rate of the engine. Air flow rate detection means,
Throttle valve opening detecting means for detecting the opening of a throttle valve interposed in the intake passage of the engine, engine rotational speed detecting means for detecting the rotational speed of the engine, and throttle valve opening in the acceleration state of the engine. An acceleration fuel injection amount setting means for setting a fuel injection amount based on a detected value with an engine rotation speed, and an intake air flow rate and an engine in an operation region other than the fuel injection amount setting operation region by the acceleration fuel injection amount setting device. Main fuel injection amount setting means for setting the fuel injection amount based on the detected value of the rotation speed, and fuel injection set by both of these setting means at the time of switching between the main fuel injection amount setting means and the acceleration fuel injection amount setting means. Deviation storage means for obtaining and storing an amount deviation, and acceleration fuel for correcting the fuel injection quantity set by the acceleration fuel injection quantity setting means based on the deviation stored thereby Injection amount correction means, and drive control means for driving and controlling the fuel injection valve in accordance with the fuel injection amount set by the front machine main fuel injection amount setting means or the fuel injection amount corrected by the acceleration fuel injection amount correction means. , And the electronically controlled fuel injection device is configured.

<Operation> According to the electronically controlled fuel injection device having such a configuration, the fuel injection control based on the throttle valve opening and the engine rotation speed, and the intake air flow rate and the engine rotation speed directly detected by the intake air flow rate detection means. When the fuel injection control based on (1) is switched based on the detection of the acceleration state, the deviation of the fuel injection amount set by each fuel control is calculated and stored. Then, by correcting the fuel injection amount set by the acceleration fuel injection amount setting means based on this deviation, the fuel injection amount deviation at the time of switching the fuel injection amount setting means is reduced.

In other words, if a deviation occurs at the time of switching the fuel injection amount setting means, it is assumed that there is an error in the setting amount by the acceleration fuel injection amount setting means, and the acceleration fuel injection amount setting means is required to eliminate this error. The fuel injection amount set by is corrected.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

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

In this figure, an engine rotation speed signal N, which is the output of a rotation speed sensor 1 as an engine rotation speed detection means, is an output of an air flow meter 2 as an intake air flow rate detection means for directly detecting the intake air flow rate of the engine. Intake air flow rate signal
Q, the output of the throttle valve opening sensor 3 as the throttle valve opening detection means, the opening signal α of the throttle valve (not shown) interposed in the intake passage of the engine, and the output of the water temperature sensor 4 of the engine. The cooling water temperature signal Tw is input to the control unit 5 containing a microcomputer including an input / output device, a storage device, and a central processing unit, and the control unit 5 is set based on these signals as described later. The injection pulse signal is output to the drive circuit 6 of the fuel injection valve 7.

That is, in this embodiment, the control unit 5 is
The throttle valve opening sensor 3 constitutes the engine acceleration state detecting means, and the drive circuit 6 constitutes the drive control means, while the acceleration fuel injection amount setting means, the main fuel injection amount setting means, and the fuel injection amount. The deviation storage means and the acceleration fuel injection amount correction means are provided as software.

Next, the operation will be described based on the flowchart of FIG.

In step (indicated as "S" in the figure, the same applies hereinafter) 1, the engine speed detected by each sensor
N, intake air flow rate Q, throttle valve opening α and cooling water temperature Tw
Enter. In step 2, it is determined whether or not 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 previously input. That is, when Δα indicates a rate of change to the open side that is equal to or greater than a predetermined value, it is determined that the engine is in an accelerating state, and the routine proceeds to step 3.

In step 3, a map of the intake air flow rate Qs (hereinafter referred to as α-N, which is stored in advance in association with a plurality of operating regions having the throttle valve opening α and the engine rotation speed N as parameters, is stored.
From the map), the intake air flow rate Qs in the operation region is searched based on the throttle valve opening α and the engine speed N input in step 1.

Here, the intake air flow rate Qs stored by using the throttle valve opening α and the engine rotation speed N as parameters is obtained in advance by experiments or the like, and approximated to an actual value that does not include the intake manifold filling amount or the like. It is a thing. Further, when the intake air flow rate Qs is obtained by the search as described above, there is almost no response delay in detection because it is based on the throttle valve opening α and the engine rotation speed N that trigger the change of the intake air flow rate. You can say it.

In step 4, the basic fuel injection amount Tp ₁ (= K × Qs / N; K is a constant) is calculated by the intake air flow rate Qs retrieved in step 3. Then, in the next step 5, the basic fuel injection amount Tp ₁ of the calculation result in step 4 is sequentially updated and stored.

In step 6, correction calculation of the basic fuel injection amount Tp ₁ calculated in step 4 is performed based on the deviation ΔTp calculated and set in step 10 (Tp ← Tp ₁ −ΔTp).

On the other hand, when it is determined in step 2 that the engine is not in the acceleration state, it is determined in step 7 whether the elapsed time from the first acceleration detection is within the predetermined time T ₁ (for example, 1 second). Here, the predetermined time T _1, when the throttle valve is opened from the idle state (fully closed state the throttle valve), the air charge into the intake manifold are time and substantially matched to the end. Therefore, when the elapsed time is within the predetermined time T ₁ , it is estimated that the intake air flow rate Q detected by the air flow meter 2 has a large error. Therefore, in step 7, the elapsed time is the predetermined time T ₁
If it is determined to be within the range, go to steps 3 to 6,
The basic fuel injection amount Tp ₁ is calculated based on the retrieved intake air flow rate Qs, as in the case where it is determined in step 2 that the engine is in the accelerated state.

When it is determined in step 7 that the predetermined time T ₁ or more has elapsed, that is, when the engine is not in the acceleration state and the predetermined time T ₁ has elapsed since acceleration, the process proceeds to step 8 and step 1 The basic fuel injection amount is based on the intake air flow rate Q which is the input value detected by the air flow meter 2.
Tp ₂ (= K × Q / N; K is a constant) is calculated. In this operating region, the air flow meter 2 is not operated as shown in FIG. 4 because the intake manifold filling amount is not detected.
The intake air flow rate Q detected by is substantially accurate.

As described above, at the time of acceleration with a large detection error by the air flow meter 2 (when acceleration is detected or within a predetermined time T ₁ from the acceleration detection), the throttle valve opening α and the engine rotation speed with a relatively small detection error are detected. Since the basic fuel injection amount Tp ₁ is set by the intake air flow rate Qs searched based on N, the fuel injection amount is set substantially in accordance with the actual intake air flow rate, and the air-fuel ratio is made richer or leaner. Can be prevented in advance.

Further, in the operating region where the detection error of the air flow meter 2 is small (except during acceleration), the basic fuel injection amount Tp ₂ is set based on the detection value of the air flow meter 2, so there is a change in the air density. Also, the actual intake air flow rate is detected, and fuel injection is performed in accordance with the required value of the engine.

When the basic fuel injection amount Tp ₂ is set in step 8, whether or not the fuel injection amount setting based on the intake air flow rate Q detected by the air flow meter 2 is the first time, that is, until the previous time, from the α-N map While the fuel injection amount has been set based on the search value Qs, it is determined in step 9 whether or not the basic fuel injection amount Tp ₂ has been set based on the intake air flow rate Q detected by the air flow meter 2 this time. .

Here, when it is determined that it is the first time, the step
Proceed to step 10 and calculate the deviation ΔTp. The deviation ΔTp is
Basic fuel injection amount Tp ₁ set in step 4 last time
To the basic fuel injection amount Tp set in step 8 this time
It is a value obtained by subtracting ₂ (ΔTp ← Tp ₁ −Tp ₂ ). That is, the deviation ΔTp is the basic fuel injection amount set in step 4 and stored in step 5 when the control based on the α-N map is switched to the control based on the detected value of the air flow meter 2.
The difference between Tp ₁ and the basic fuel injection amount Tp ₂ set in step 8 this time is shown.

The deviation ΔTp calculated and set in step 10 is stored in step 11 and used for correction calculation of the basic fuel injection amount Tp ₁ in the next and subsequent steps 6. That is, when the deviation ΔTp is set, the fuel control based on the next α-N map (hereinafter referred to as α-N control) is performed (step 3 to
6), this deviation Δ from the calculated basic fuel injection amount Tp ₁
By subtracting Tp, the set basic fuel injection amount Tp does not show a stepwise rapid change when switching from the control based on the intake air flow rate Q detected by the air flow meter 2.

Specifically, for example, when switching from α-N control, α-
The basic fuel injection amount Tp ₁ set based on the N control is larger than the basic fuel injection amount Tp ₂ set based on the intake air flow rate Q directly detected by the air flow meter 2 by a predetermined amount, and the switching is performed. At this time, when the basic fuel injection amount Tp shows a sudden decrease, the deviation ΔTp is set as a positive value as an error amount in the α-N control, and when the α-N control is performed next, the set basic fuel is set. The basic fuel injection amount Tp set by subtracting this deviation ΔTp from the injection amount Tp ₁ is reduced and approximated to the basic fuel injection amount Tp ₂ set based on the detected intake air flow rate Q,
This is to prevent a sudden change in the basic fuel injection amount Tp at the time of switching.

When it is determined to be NO in step 9, the deviation Δ
Proceed to step 12 without setting Tp calculation.

The basic fuel injection amount Tp ₁ set by correcting the basic fuel injection amount Tp ₁ in step 6 or the basic fuel injection amount Tp ₂ set in step 8 is corrected in step 12 to set the fuel injection amount Ti. It That is, from the various operating states such as the cooling water temperature Tw detected by the water temperature sensor 4 and the engine accelerating state, the correction factors based on the respective operating states stored and set in the storage device are searched, and the center of these correction factors is searched. A fuel injection amount Ti obtained by correcting the basic fuel injection amount Tp is set by various correction coefficients COEF obtained by calculation in a calculation device.

When the fuel injection amount Ti is set in step 12, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the drive circuit 6 of the fuel injection valve 7 to perform fuel injection in step 13.

In the present embodiment, the deviation ΔTp is obtained when switching from the α-N control to the control based on the detected intake air flow rate Q, but conversely, from the control based on the detected intake air flow rate Q, α
The deviation ΔTp may be obtained when switching to the −N control.

<Effects of the Invention> As described above, according to the present invention, the intake air detected at the time of switching to the fuel injection amount setting based on the detection values of the throttle valve opening degree and the engine rotation speed or directly detected from such setting. At the time of switching to the setting of the fuel injection amount based on the detected value of the flow rate and the engine rotation speed, the set fuel injection amount changes abruptly in steps due to the error of the fuel injection amount setting based on the opening degree and the rotation speed. This has the effect of preventing this and avoiding an acceleration shock and deterioration of exhaust properties.

[Brief description 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 flow chart showing a fuel injection amount setting control in the same 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] 1. An engine acceleration state detecting means for detecting an acceleration state of an engine, an intake air flow rate detecting means for directly detecting an intake air flow rate of the engine, and an opening of a throttle valve interposed in an intake passage of the engine. Throttle opening degree detecting means for detecting the engine speed, engine rotation speed detecting means for detecting the rotation speed of the engine, and the fuel injection amount based on the detected values of the throttle valve opening degree and the engine rotation speed in the acceleration state of the engine. And a fuel injection amount based on the detected values of the intake air flow rate and the engine rotation speed in an operation region other than the fuel injection amount setting operation region by the acceleration fuel injection amount setting unit. A main fuel injection amount setting means to be set, and a fuel injection amount deviation stored and obtained when a deviation between the main fuel injection amount setting means and the acceleration fuel injection amount setting means is determined by the setting means. Storage means, acceleration fuel injection quantity correction means for correcting the fuel injection quantity set by the acceleration fuel injection quantity setting means based on the deviation stored in the fuel injection quantity deviation storage means, and the main fuel injection Electronically controlled fuel for an internal combustion engine, comprising drive control means for driving and controlling a fuel injection valve according to the fuel injection amount set by the amount setting means or the fuel injection amount corrected by the acceleration fuel injection amount correction means. Injection device.