JPH0792006B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to improvement during acceleration operation.

<Prior Art> The following is a conventional example of an electronically controlled fuel injection device for an internal combustion engine (see Japanese Utility Model Application No. 60-066558).

That is, the basic injection amount Tp = K × Q / N from the intake air flow rate Q detected by the air flow meter and the engine rotation speed N.
(K is a constant) and at the same time, after calculating various correction coefficients COEF mainly according to the water temperature, the air-fuel ratio feedback correction coefficient α and the correction coefficient Ts based on the battery voltage, the fuel injection amount Ti = Tp × during steady operation Calculate COEF x α + Ts.

Then, for example, in a single point injection system (hereinafter referred to as SPI method), an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the fuel injection valve in synchronization with an ignition signal or the like every 1/2 revolution of the engine. Supply fuel to the engine.

Further, during acceleration operation, the increased injection amount during acceleration is calculated from the rate of change of the intake throttle opening, and the increased injection amount is calculated as the fuel injection amount Ti.
To increase the fuel output during acceleration and increase the engine output.

The acceleration increase is also performed by interrupt injection performed by interrupting the injection pulse during acceleration during the normal injection pulse signal.

<Problems to be Solved by the Invention> However, in such a conventional electronically controlled fuel injection device, the fuel injection amount is calculated based on the intake air flow rate detected by the air flow meter interposed in the engine intake passage. Therefore, there was a problem especially during acceleration operation.

That is, the period during which the throttle valve is operating (4th
At t ₁ ) in the figure, the intake air flow rate detected by the air flow meter due to the response delay (shown by the solid line in FIG. 4, hereinafter referred to as the airflow intake air flow rate) is the true intake air flow rate supplied to the engine (see FIG. 4). It is lower than the middle dashed line).

Immediately after the opening operation of the throttle valve is finished, the airflow intake air flow rate greatly exceeds the true intake air flow rate due to the overshoot, and the airflow intake air flow rate is later than the true intake air flow rate due to the undershoot. It drops significantly. Then, thereafter, the airflow intake air flow rate comes close to the true intake air flow rate. In a flap type air flow meter in which a plate-like flap is provided in the intake passage to detect the intake air flow rate, such a phenomenon has become remarkable due to the inertial force of the flap.

As a result, when fuel is supplied to the engine from the fuel injection amount calculated based on the air flow intake air flow rate so that the air-fuel ratio becomes an appropriate value, the fuel injection amount does not correspond to the true intake air flow rate The fuel ratio deviates greatly from the proper value. Therefore, the actual air-fuel ratio becomes rich during the overshoot period (t _{2 in} FIG. 4) in which the air flow intake air flow rate exceeds the true intake air flow rate, and the period during the opening operation of the throttle valve (t in FIG. 4) is increased. ₁ ) and the underflow period during which the airflow intake air flow rate falls below the true intake air flow rate (in Fig. 4
With t ₃ ), there is a problem that the actual air-fuel ratio becomes lean and hazing occurs.

The present invention has been made in view of such a situation, and an object thereof is to provide an electronically controlled fuel injection device capable of optimally controlling an actual air-fuel ratio.

<Means for Solving Problems> Therefore, according to the present invention, as shown in FIG. 1, the intake air flow rate detecting means B for directly detecting the intake air flow rate of the engine A and the opening degree of the throttle valve are detected. Throttle valve opening detection means C, rotation speed detection means D for detecting engine rotation speed,
Intake air flow rate setting means E for setting an intake air flow rate based on the detected throttle valve opening degree and engine rotation speed,
A valve opening speed calculation means F for calculating the valve opening speed on the basis of the detected opening degree of the throttle valve, and an acceleration operation ending time for judging the ending time of the acceleration operation of the throttle valve based on the calculated valve opening speed. The determination unit G selects the set intake air flow rate for a set time from when the end of the acceleration operation is determined, while the intake air detected by the intake air flow rate detection unit B after the set time elapses. A selection means H for selecting a flow rate, a fuel injection amount calculation means I for calculating a fuel injection amount based on the selected intake air flow rate, and an injection pulse signal corresponding to the calculated fuel injection amount to a fuel injection valve J. The driving pulse output means K for outputting is provided.

<Operation> In this way, during the set time from the end of the acceleration operation, the fuel injection amount is set by the intake air flow rate based on the opening degree of the throttle valve corresponding to the true intake air flow rate, and thus the actual air-fuel ratio is set. I tried to optimize it.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In the figure, a control device 1 including, for example, a microcomputer includes a rotation speed sensor 2 as a rotation speed detection unit
Rotational speed N signal detected by, the air flow intake air flow rate Q _A signal detected by the air flow meter 3 as the intake air flow rate detecting means, throttle detected by the throttle valve opening sensor 4 as the throttle valve opening detecting means The valve opening α signal and the cooling water temperature Tw signal detected by the water temperature sensor 5 are input.

The control device 1 operates according to the flowchart shown in FIG. 3, and outputs a drive pulse signal to the fuel injection valve 6 via the drive circuit 7.

Here, the control device 1 constitutes intake air flow rate calculation means, valve opening speed detection means, acceleration operation end time determination means, and comparison means. Further, the control device 1 and the drive circuit 6 constitute a drive pulse output means.

Next, the operation will be described with reference to the flowchart of FIG.

In S1, the detected rotational speed N and air flow intake air flow rate
Read various signals such as Q _A and throttle valve opening α.

In S2, the valve opening speed Δα of the throttle valve is calculated from the detected throttle valve opening.

In S3, based on the detected throttle valve opening α and the engine speed N, the intake air flow rate Qα (hereinafter, the search intake air flow rate Qα) corresponding to the operating region is calculated from the intake air flow rate three-dimensional map table stored in the ROM. Search).

In S4, it is determined from the calculated valve opening speed Δα whether or not the throttle valve opening operation is in progress. If YES (Δα> 0), it is determined that acceleration operation is in progress, and the process proceeds to S5 and NO (Δα = 0)
Go to S7.

At S5, the fact that the throttle valve is being opened is stored in the RAM as flag = 1, and the process proceeds to S6. Also, the flag =
0 indicates a state where the throttle valve opening speed Δα = 0.

In S6, to step S15 to compare directly detected airflow intake air flow rate Q _A and the search intake air flow rate Qa by the air flow meter 3, when the Q _A ≧ Qa to be described later when Q _A <Qa proceeds to S16 described later move on.

In S7, the flag stored in the RAM is determined. When the flag = 1, it is determined that the acceleration operation of the throttle valve has ended, and the process proceeds to S8. When the flag = 0, it is continuously determined to be the steady operation state, and the process proceeds to S9. .

In S8, the first timer is reset to newly start counting, and then the process proceeds to S9.

In S9, the flag = 0 is stored in the RAM, and then the process proceeds to S10.

In S10, the count time T _M1 of the first timer is compared with the control delay setting time Acc _1, and when T _M1 ≧ Acc ₁ , the process proceeds to S16.
When T _M1 <Acc ₁ , proceed to S11. Here, the delay setting time Acc ₁ is larger than the time from the end of the opening operation of the throttle valve to the time when the air flow intake air flow rate Q _A and the search intake air flow rate Q α become substantially the same as shown in FIG. Is set to.

In S11, it is determined whether or not the air flow intake air flow rate Q _A has become less than the search intake air flow rate Qα. If YES, the process proceeds to S12, and if NO, the process proceeds to S13.

In S12, the count value of the second timer is reset and returned to the initial value, and in S13, +1 is added to the count value T _M2 of the second timer and the process proceeds to S14.

In S14, the count time T _M2 of the second timer and the control time Acc ₂
And T _M2 ≧ Acc ₂ , proceed to S16 and T _M2 <Acc ₂
If so, proceed to S15. Here, the control time Acc ₂ is set to be larger than the time from when the air flow intake air flow rate Q _A becomes less than the search intake air flow rate Q α until they become similar values.

In S15, the basic injection amount Tp (= K.Qα / N, K is a constant) is calculated based on the retrieved intake air flow rate Qα and the rotation speed N.

In S16, the basic injection amount Tp (= KQ _A / N) is calculated based on the air flow intake air flow rate Q _A and the rotation speed N.

In S17, the final fuel injection amount Ti is calculated as in the conventional example.

In S18, an injection pulse signal having a pulse width corresponding to Ti calculated in S17 is output to the fuel injection valve 7 via the drive circuit 6.

In this way, the fuel injection amount Ti is calculated based on the search intake air flow rate Qα from the end of the acceleration operation until the control delay setting time Acc ₁ or the control Acc ₂ elapses. As a result, the period when the air flow intake air flow rate Q _A is different from the true intake air flow rate actually sucked into the engine (4th
At t ₂ , t ₃ ) in the figure, the fuel injection is performed at the search intake air flow rate Qα corresponding to the true intake air flow rate, so that the actual air-fuel ratio can be set to an appropriate value, so that generation of hazing can be prevented.

Further, during the opening operation period of the throttle valve (t _{1 in} FIG. 4), the fuel injection amount is calculated based on the larger value of the air flow intake air flow rate Q _A and the search intake air flow rate Q α. The fuel injection amount can be increased and the acceleration performance can be improved.

<Effects of the Invention> As described above, according to the present invention, the fuel injection amount is calculated from the intake air flow rate set based on the opening of the throttle valve from the end of the acceleration operation of the throttle valve to the set time. As a result, the actual air-fuel ratio of the engine can be optimized,
Therefore, the generation of hazing can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG.
FIG. 4 is a diagram for explaining the conventional drawbacks and the operation of the embodiment. 1 ... Control device, 2 ... Rotation speed sensor, 3 ... Air flow meter, 4 ... Throttle valve opening sensor, 6 ... Drive circuit, 7 ... Fuel injection valve

Continuation of front page (56) Reference JP-A-60-62638 (JP, A) JP-A-59-170433 (JP, A) JP-A-59-176428 (JP, A) JP-A-62-258143 (JP , A) Actual development 62-184145 (JP, U) Actual development 62-183044 (JP, U)

Claims (1)

[Claims] 1. An intake air flow rate detecting means for directly detecting an intake air flow rate of an engine, a throttle valve opening degree detecting means for detecting an opening degree of a throttle valve, a rotational speed detecting means for detecting an engine rotational speed, and a detecting means. Intake air flow rate setting means for setting the intake air flow rate based on the detected throttle valve opening and engine speed, and valve opening speed calculation means for calculating the valve opening speed based on the detected opening of the throttle valve. And an acceleration operation end time determination means for determining the end time of the acceleration operation of the throttle valve based on the calculated valve opening speed, and the set suction for a set time from the time when the acceleration operation end time is determined. While selecting the air flow rate, after the set time has elapsed, the selection means for selecting the intake air flow rate detected by the intake air flow rate detection means, and the fuel injection amount is calculated based on the selected intake air flow rate. That the fuel injection amount calculating means, calculated driving pulse output means for the injection pulse signal corresponding to the fuel injection amount is output to the fuel injection valves, electronically controlled fuel injection system for an internal combustion engine, characterized in that it comprises a.