JPH0320579B2 - - 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, and more particularly to a technique for improving engine startability.

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

That is, 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) is calculated.

Then, an injection pulse signal with a pulse width corresponding to the calculated fuel injection amount Ti is output to the fuel injection valve, thereby injecting and supplying a predetermined amount of fuel to the engine (Japanese Unexamined Patent Publication No. 59-203828, etc. reference).

<Problems to be Solved by the Invention> By the way, in such a conventional electronically controlled fuel injection device, fuel injection is started immediately when the engine starts rotating by the starter motor when the engine is started. When the engine is cold, there is a risk that a large amount of unburned fuel will be generated in the early stages of startup, impairing startability.

In other words, normally, the ignitability is improved by increasing the fuel injection amount at startup, but even if such an increase is performed at the beginning of cold engine startup, the atomization of the fuel will not be achieved. It is inevitable that ignition errors will occur due to insufficient flame propagation due to insufficient heat or low temperature of the combustion chamber walls. Therefore, even if fuel injection is started from the beginning of engine rotation by the starter motor,
There is a risk that the fuel injected at the early stage of startup may not burn well and become unburned fuel, which could cause the spark plug to become wet or be exhausted as is, worsening the exhaust properties. In other words, there is a risk that the fuel that is injected and supplied at the initial stage of engine startup becomes a wasteful supply that does not contribute to engine startup.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the startability of the engine by suppressing the generation of unburned fuel when starting the engine.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, the fuel injection amount setting method sets the fuel injection amount based on the engine operating state detected by the engine operating state detection means. and a drive control means for controlling the opening and closing of a fuel injection valve according to a set fuel injection amount in an electronically controlled fuel injection system for an internal combustion engine, which detects a starting state of the engine. The operation of the drive control means is forcibly stopped between the time when the start of the engine is detected by the engine start state detection means and the cumulative engine speed reaches a predetermined number of revolutions. A fuel injection stop means for stopping fuel injection is provided. Further, in the above configuration, the predetermined rotation speed of the cumulative engine rotation speed is variably set according to the engine temperature.

<Function> According to this electrostatic control fuel injection device, when the start of engine starting is detected by the engine starting state detection means, the fuel injection amount is set from this point until the cumulative engine speed reaches a predetermined speed. Even if the fuel injection amount is set by the means, the fuel injection amount stopping means forcibly stops the operation of the drive control means and stops the fuel injection.

In other words, fuel injection is not started immediately when the engine starts, but injection is started after the cumulative engine speed from the start of engine startup reaches a predetermined speed, and until the cumulative engine speed reaches a predetermined speed. During this period, fuel injection is stopped, and the engine compresses air during the injection stop period to increase the fuel chamber temperature, and when fuel injection is started later, sufficient fuel atomization for ignition is achieved. This makes it possible to obtain properties such as fire resistance and flame propagation properties. Here, by variably setting the cumulative rotational speed at which the injection is started according to the engine temperature, a desired increase in combustion chamber temperature can be obtained without unnecessarily prolonging the fuel injection stop period.

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

FIG. 2 shows the hardware configuration of one embodiment of the 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, the intake air flow rate signal Q is the output of the air flow meter 2, the engine cooling water temperature signal Tw is the output of the water temperature sensor 3, and the starter switch (starter switch) The ON/OFF signals of the switch (switch) 7 that controls the energization of the motor are transmitted by the control unit 4, which has a built-in microcomputer that is composed of an input/output device, a storage device, and a central processing unit.
Based on these signals, the control unit 4 outputs an injection pulp signal set as described below to the drive circuit 6 of the fuel injection valve 5, and also outputs an injection pulp signal to the drive circuit 6 of the fuel injection valve 5. output of the injection pulse signal is stopped during the period until the number reaches a predetermined number).

That is, in this embodiment, the control unit 4 constitutes an engine starting state detection means with the starter switch 7, and a drive control means with the drive circuit 6, while the control unit 4 constitutes a drive control means with the starter switch 7. and fuel injection stop means are provided in terms of software. In this embodiment, the engine operating state detection means corresponds to the rotational speed sensor 1, air flow meter 2, and water temperature sensor 3.

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 rotational speed N, intake air flow rate Q, and engine cooling water temperature Tw detected by each sensor, and the ON/OFF state of the starter switch 7 are determined. OFF
Input the signal.

In step 2, turn on the starter switch 7.
If it is determined to be OFF,
That is, if it is determined that the starter motor is not driven and the engine is not started, the routine jumps to step 5 and normal fuel injection control, which will be described later, is performed. On the other hand, if it is determined that the starter switch 7 is ON, that is, if it is determined that the engine is in a starting state where the starter motor is being driven, the process proceeds to the next step 3.

In step 3, starter switch 7 is turned on.
The period from when the engine is started (starting) until the fuel injection is started, that is, the period during which the fuel injection is forcibly stopped is set. Here, the injection stop period is
The cumulative rotation speed of the engine from the start of the engine is the specified rotation speed n
In this embodiment, the predetermined rotation speed n is set higher as the engine cooling water temperature Tw is lower and the fuel atomization is worse. The timing at which fuel injection starts is delayed from the start of the engine when the engine is cold.

In step 4, it is determined whether the cumulative number of revolutions since the ON state of the starter switch 7 is first determined is less than or equal to the predetermined number of revolutions n set in step 3. Here, if it is determined as YES, that is, if the cumulative number of revolutions since the starter switch 7 is turned on has not reached the predetermined number of revolutions n, steps 5 to 7 are jumped to inject fuel. Return without doing anything.

On the other hand, if it is determined to be ON in step 4, that is, if the cumulative number of revolutions exceeds the predetermined number of revolutions n, the routine proceeds to steps 5 to 7, where normal fuel injection control is performed.

In this way, even when the starter switch 7 is turned ON and the engine is rotated by the starter motor, fuel injection does not start immediately, but instead starts at a predetermined cumulative rotation speed n that is set according to the engine cooling water temperature Tw.
Only after the engine has rotated will fuel injection begin. That is, when the engine starts rotating, conventionally an injection pulse signal corresponding to the fuel injection amount Ti is output as shown by the dotted line in FIG. 4, but fuel injection is stopped during the n rotations. Therefore, only air is taken in, compressed, and discharged during the rotation speed n when fuel injection is not determined, and it is possible to suppress the generation of unburned fuel during this period when ignition errors are likely to occur. and,
The heat generated by compressing the air warms the combustion chamber walls as shown in FIG.

If the generation of unburned fuel at the initial stage of startup is suppressed, wetting of the ignition plug and deterioration of exhaust properties due to unburned fuel can be prevented. In addition, as mentioned above, if the combustion chamber wall is warmed before the start of fuel injection, flame propagation will be good, and at the start of fuel injection (starter switch 7
This improves the combustion of the air-fuel mixture after n rotations from ON, and together with preventing the spark plug from getting wet, it is possible to improve the startability of the engine. In addition, since the period for stopping injection is determined based on the cumulative rotational speed according to the engine temperature, air compression can be performed a predetermined number of times while fuel injection is stopped, and the desired combustion chamber temperature can be achieved. It becomes possible to obtain the increase without unnecessarily prolonging the fuel injection stop period.

On the other hand, in the early stages of engine startup (starter switch 7
Steps 5 to
7 fuel injection control is performed.

In step 5, a basic fuel injection amount Tp (=K×Q/N; K is a constant) is calculated based on the engine rotational speed N and intake air flow rate Q input in step 1.

Then, in the next step 6, the basic fuel injection amount Tp calculated in step 5 is corrected to obtain the final fuel injection amount Ti. That is, from various operating states such as the engine cooling water temperature Tw and engine acceleration state entered in step 1, correction coefficients based on each operating state set and stored in the storage device are retrieved, and these correction coefficients are centrally calculated. Set the fuel injection amount Ti (=Tp×COEF×α+Ts) by correcting the basic fuel injection amount Tp using various correction coefficients COEF and air-fuel ratio feedback correction coefficient α calculated by the device, as well as the battery correction amount Ts. do.

In step 7, 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 5 to perform fuel injection.

<Effects of the Invention> As explained above, according to the present invention, fuel injection is stopped from when the starting state of the engine is detected until the cumulative engine speed reaches a predetermined speed. , it is possible to avoid the generation of unburned fuel in the initial stage of engine startup, prevent wetting of the spark plug due to unburned fuel and deterioration of exhaust characteristics due to unburned fuel, and improve engine startability. can.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIG. 3 is a flowchart showing fuel injection control in the same embodiment, and FIG.
The figure is a time chart showing control in the same embodiment. DESCRIPTION OF SYMBOLS 1... Rotation speed sensor, 2... Air flow meter, 3... Water temperature sensor, 4... Control unit, 5... Fuel injection valve, 6... Drive circuit, 7...
...Starter switch.

Claims (1)

[Scope of Claims] 1. Fuel injection amount setting means for setting the fuel injection amount based on the engine operating state detected by the engine operating state detection means, and a fuel injection amount setting means for setting the fuel injection amount according to the set fuel injection amount. An electronically controlled fuel injection device for an internal combustion engine, comprising: a drive control means for controlling an opening/closing drive; and an engine start state detection means for detecting a start state of the engine; and a fuel injection stop means for forcibly stopping the operation of the drive control means and stopping fuel injection until the cumulative engine speed reaches a predetermined speed. The engine's electronically controlled fuel injection system. 2. The internal combustion engine according to claim 1, wherein a predetermined number of cumulative engine revolutions at which fuel injection is stopped by the fuel injection stop means is variably set according to engine temperature. The engine's electronically controlled fuel injection system.