JPS608334B2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection device applied to a spark ignition engine, and particularly to acceleration correction of fuel injection amount.

Conventionally, in this type of electronically controlled fuel injection system, the intake air amount of the engine is measured by a measuring plate placed upstream of the throttle valve. It was thought that there was no need for a special acceleration correction of the fuel injection amount.

However, in an engine that injects fuel into all cylinders simultaneously twice per engine cycle, due to the time delay in the control system, the throttle valve may suddenly go from fully closed or from a very small position to fully open or to a large opening. If the throttle valve is fully closed or opened slightly, the amount of fuel will be injected, and the engine will start to This results in a misfire or near-misfire situation, resulting in a delay in the engine starting up when accelerating, resulting in poor acceleration.
This results in the problem of increased HC emissions.

To solve this problem, it is possible to generate one acceleration pulse signal when the throttle valve reaches a set opening or more, and increase the fuel injection amount using this acceleration pulse signal.
In this method, when attempting to obtain a large output torque without causing a misfire during sudden acceleration from the low to medium speed range of the engine, the inventors' experiments have shown that an acceleration pulse signal with a pulse time width of 5 to 8 seconds is required. This causes the problem that the fuel injection amount is increased too much during acceleration from a high-speed rotating castle where there is almost no delay time in the system, causing the engine to afterfire.

This invention was made in view of the above problem, and outputs an acceleration pulse signal when the engine load amount exceeds a set value, and also outputs an acceleration pulse signal. By configuring the configuration to include an acceleration correction circuit that erases the acceleration pulse signal regardless of the load amount when the rotation speed is higher than the set rotation speed, it is possible to prevent deterioration of acceleration performance and increase in HC emissions due to engine misfire, and at the same time The purpose is to prevent engine afterfire.

The present invention will be described below with reference to embodiments shown in the drawings.

In the figure, the rotational speed sensor generates a pulse signal with a frequency corresponding to the engine rotational speed, and uses, for example, a primary ignition signal of an ignition coil. The output pulse signal of the rotational speed sensor is shaped into a square wave pulse signal by a waveform shaping circuit 2, divided by a frequency dividing circuit 3,
A pulse signal N whose pulse width n is inversely proportional to the engine speed is output.

The frequency division ratio of this frequency dividing circuit 3 is selected in accordance with the number of fuel injections per engine cycle. For example, if the engine is injected twice per i cycle, it is 1'2 for 4 cylinders, and 1' for 6 cylinders. Selected as number 3. The arithmetic circuit 4 divides the intake air amount of the engine by the engine rotation speed using the pulse signal N from the frequency dividing circuit 3 and the output signal of the intake air amount sensor 5, which generates an electrical signal according to the amount of intake air of the engine. A pulse signal T having the calculated time width is generated.

The waveform shaping circuit 2 is designed to generate a pulse signal Tm with a preset constant time width tm, and by AND logic between the pulse signal Tm and the pulse signal T,
It is configured such that the time width L' does not exceed the time width tm. The multiplier circuit 6 multiplies various correction signals from the operating condition sensor 7, which includes an engine cooling water temperature sensor, an intake air temperature sensor, etc., into a pulse signal T, and generates a pulse with a pulse duration t2, which takes into account engine warm-up correction, etc. Outputs signal L.

The voltage correction circuit 8 inputs the pulse signal T2 from the summing circuit 6, and the electromagnetic fuel injection valve! “In order to correct this change in fuel injection amount depending on the power supply voltage, a pulse signal L having a pulse time width t3 corresponding to the power supply voltage is output.

The OR circuit 9 adds the time widths of the pulse signals T, ?T2, and T3 from the arithmetic circuit 4, the multiplication circuit 6, and the voltage correction circuit 8, and generates a basic pulse with a pulse time width (t, 10, 20, 20, etc.). The signal T is supplied to the output circuit Tatami 0, and the electromagnetic fuel injection valve 11 connected for simultaneous injection in each cylinder is actuated. It is configured as a multi-pipe layer with variable time width as described in Japanese Patent No. 49-67016.

The multipiperator of the multiplier circuit 6 has a capacitor that is charged during the pulse time width of the pulse signal T from the arithmetic circuit 4, and a pulse with a pulse time width t2 equal to the discharge duration etc. after the completion of charging. It generates the signal L, and is configured such that the larger the current flowing from the external circuit during charging, the larger the pulse time width, and the larger the current flowing from the external circuit during discharging, the larger the pulse time width. To explain further, the output of the frequency dividing circuit 3 is connected to the monostable multivibrator 4 and the comparison circuit 85. A pulse signal N with a time width n inversely proportional to the speed is compared with a pulse signal Ns with a constant time width ns corresponding to the set rotational speed inputted from the monostable multipipelator Turtle in synchronization with this pulse signal.

This comparator circuit 5 is composed of a flip-flop (for example, SN7474 manufactured by Texas Instruments), and a pulse signal N is supplied to a delay terminal D, and a pulse signal N is supplied to a clock terminal CL.
A pulse signal Ns is input to the output terminal Q, and n
It is configured to generate a "1" level signal when Zns, that is, when the engine rotation speed is higher than the set rotation speed, and to generate a "0" level signal when n<ns, that is, when the engine rotation speed is smaller than the set rotation speed. .

The throttle sensor 6, which detects the throttle valve opening of the engine, is composed of a throttle switch etc. that reaches the throttle valve 20, and generates a "1" level signal when the throttle valve opening is less than the set opening, and detects the throttle valve opening. is configured to generate a d'0'' level signal when the function is greater than or equal to a set function.

The monostable multipipulator 17 is connected to the throttle sensor 1
At the moment when the output signal of No. 6 changes from the "1" level to the "0" level, one acceleration pulse signal t having a preset pulse time width is generated. By passing the output of the comparison circuit 15 and the output of the monostable multipipulator 17 through the NOR gate 18, the NOR gate 1 is connected only while the engine rotation speed is below the set rotation speed and the pulse signal T4 is output. The output of 8 becomes “0” level, and inverter 1
9, the output circuit 101 is supplied to the electromagnetic injection valve 11.
It has been purchased to drive the valve.

In the above configuration, "S.

If the throttle valve 20 is in the fully open or small opening position and the engine is operating at less than the set rotational speed, then the throttle valve 2Q is suddenly opened above the set opening and the engine is suddenly accelerated. Instantly, one acceleration pulse signal is generated from the monostable multipipulator 17, and the NOR
Since the gate IS is open, this pulse signal T4 is inputted to the output circuit 101 via the inverter 19, and the CR
The electromagnetic fuel injection valve is driven independently of the injection timing by the basic pulse signal T of the circuit 9. Therefore, a sufficient amount of fuel is injected into the engine to match the rapidly increasing amount of intake air during sudden acceleration, and the engine quickly starts to rotate without misfiring, resulting in good acceleration.

On the other hand, in a high-speed operation mode where the engine is operated at a speed higher than the set rotation speed, when the throttle valve 2Q reaches the set opening or higher, the NOR gate 8 is activated by the output signal of the comparator circuit 15.
' Closes and the acceleration pulse signal T4 is erased.

Therefore, the increase in acceleration amount by this acceleration pulse signal T4 is stopped, and engine afterfire due to an excessive increase in the fuel injection amount does not occur during acceleration in a high-speed operating range where there is almost no delay time in the system.As stated above, According to this invention, `` engine misfire during acceleration is prevented with low engine speed and medium range driving conditions, improving acceleration performance and reducing HC emissions. This has the excellent effect of eliminating oversupply and preventing engine afterfire.

A brief description of Hakanran The figure is a block diagram showing an embodiment of the invention.

11...Electromagnetic fuel injection valve 13...Acceleration correction circuit, Tortoise 6...Throttle sensor, 20...Throttle valve.

Claims (1)

[Claims] 1. In an electronically controlled fuel injection device that determines the amount of fuel according to the operating state of the engine using the pulse time width of a basic pulse signal applied to an electromagnetic fuel injection valve, the load amount of the engine is detected and the detection signal is output. A load sensor generates an acceleration pulse signal with a set pulse time width when the load amount exceeds a set value based on the detection signal of this load sensor, and furthermore, when the engine speed exceeds the set rotation speed, the load acceleration correction means configured to erase the acceleration pulse signal regardless of the amount, and to open the electromagnetic fuel injection valve independently of the basic pulse signal only when the acceleration pulse signal is output. An electronically controlled fuel injection device characterized by: