JPS5982541A - Electronic control type fuel injector for internal- combustion engine - Google Patents

Abstract

PURPOSE:To permit the pulse width-flow-rate characteristic of a fuel 1 injection valve to be controlled by the control within a specific narrow range by making constant the pulse width of the pulse for driving the fuel injection valve and making the number of pulses per time proportional to the amount of air inhaled. CONSTITUTION:The output terminal of an air flow meter 11 is connected to an integrator 13. The output terminal of a comparator 14 is connected to the reset terminal of the integrator 13 and further connected to a monostable circuit 15. The output of the comparator 14 forms the signal having the frequency proportional to the amount of air inhaled. Thus monostable circuit 15 is triggered by said signal. Therefore, the amount of fuel corresponding to the amount of air inhaled is obtained by making the number of injetion per time proportional to the amount of air inhaled. Thus, fuel injection can be controlled accurately with simple constitution.

Description

[Detailed description of the invention] The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

Conventionally, in an electronically controlled fuel 1'1 injection system for an internal combustion engine, the first
A fuel injection valve as shown in the figure is used. In this fuel injection valve, the needle valve 2 in the nozzle body 1 is biased to the input by the spring 3.
The seat part 2a at the tip is seated on the sorting part 1a of the nosulfody 1 and the valve is closed, and when a driving pulse is given to the electric key coil 4 and the iron core 5 is excited, the iron core 5 attaches it to the twenty-one torque half 2. The iron piece 6 is attracted, and the needle valve 2 is lifted to a position where its flange 2b comes into contact with a stopper plate 7 disposed on the rear surface of the nozzle body 1, and the needle valve 2 is opened. Therefore, theoretically, the valve opening time is determined according to the drive pulse, and a fuel injection amount proportional to the valve opening time can be obtained.

In order to obtain a fuel injection amount corresponding to the intake air amount, the intake air amount (r+(/h)) detected by the intake air amount detector (air flow meter) and the engine rotation detected from the ignition signal of the ignition coil are used. From the number (r/min),
The arithmetic circuit in the control unit calculates the intake air amount per unit rotation speed, calculates the fuel injection amount, that is, the pulse of the fuel injection valve drive pulse, and calculates the fuel injection light drive pulse having the middle of this pulse. Each time the fuel is output and the fuel injection valve is driven, more appropriate +ffA l'l is injected.

However, in the fuel injection valve ζ, during the pulse of the drive pulse given to it (m5ec) and the furnace λ fuel flow rate (cc
/10 (10str) is not necessarily a straight line, and the actual pulse-flow rate characteristics are as shown in Figure 2, and the actual characteristics deviate from the required characteristics in the low-pulse region below ]゛o. I'm going to wait.

This is the needle valve 2 in the fuel injection valve described above.
When the flange 2b of the needle valve 2 touches the l-flange plate 7, the seat 2a of the needle valve 2 touches the seat 1 of the nosulfoty 1.
It is presumed that this is due to jumping occurring when hitting point a.

Therefore, in reality, there is a limit to the usable pulses in order to perform accurate control.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to control the pulse of the fuel injector by keeping the duration of the fuel injector driving pulse constant and by making the number of pulses per unit time proportional to the amount of intake air. The purpose is to make it sufficient to manage the medium flow rate characteristics within a specific narrow range.

Therefore, in the present invention, the period of the fuel injection valve drive pulse is determined according to the intake air amount detector that detects the intake air amount and the detection signal of this intake air amount detector, and the constant pulse 111 is determined based on this period. An electronically controlled fuel injection device is provided, which includes a drive pulse generation circuit that outputs an injection drive pulse to a fuel injection valve.

Examples will be described below.

In FIG. 3, the output terminal of the intake air amount detector (air flow meter) 11 is connected to an integrator +3 +, . The output terminal of the integrator 13 is the comparator 1
4 (connected to the - side input terminal, one side input 6N of the axis ratio device 14, and the base 1% voltage Vc is input to the 1st child).The output terminal of the comparator 14 is Integral H:tI3
is connected to the reset terminal of the 111 stability circuit (
1279371 ~ times 17 &) connected to 15.

The output terminal of the small stabilizer circuit I5 is connected to the heath of the emitter-grounded transistor 16, and the other end of the fuel injection valve 17 (more specifically, its electromagnetic coil) is connected to the collector of the transistor 16, one end of which is connected to a power supply (not shown). ing.

5) A correction circuit 18 is connected to the product 13 so that the value of the integral constant with respect to the intake air amount is made variable.
be.

To explain the operation with reference to FIG. 4, when the intake air amount signal from the intake air amount detector 11 is input to the integrator 13, the output voltage of the integrator 13 is determined by an integration constant according to the intake air amount. and increases with time. When the output voltage of the integrator 13 exceeds a predetermined slice level (reference voltage Vc), the output of the comparator 14 is inverted and an H level signal is output. This signal is sent to the reset terminal of the integrator 13 to reset it, and is also sent to the monostable circuit 15,
The small stable circuit 15 outputs a driving pulse among constant pulses.

As a result, the I-run system 16 is turned on for a certain period of time, the electromagnetic coil of the fuel injection valve 17 is energized for a certain period of time, the valve is opened for a certain period of time, and a certain amount of fuel is injected.

As the intake air amount decreases (increases), the integral constant becomes smaller (larger), the time it takes for the output voltage of the integrator 13 to reach the slice level becomes longer (shorter), and the injection interval becomes longer (shorter). ) become.

In this way, although the injection amount per injection is made equal, the number of injections per unit time is made proportional to the intake air amount to obtain the fuel injection amount corresponding to the intake air amount.

Therefore, since it is constant during the pulse, the fuel injector algorithm need only be managed within a specific narrow range.

Furthermore, since it is no longer necessary to detect the rotational speed and calculate fuel injection (2), the rotational speed in centimeters is no longer necessary.

Of course, a rotation speed sensor is required for fuel cut correction, etc., which will be described later, but the reading rate can be lower than that required for calculating the injection amount, so the cost can be reduced.

Water temperature correction that corrects the amount of fuel 1'i'lJ according to the engine cooling water temperature, or
When performing a fuel cut correction of 1-1, the correction circuit I8 may be used to change the value of the integral constant with respect to the intake air amount. Furthermore, by changing the reference voltage applied to the comparator 14, water temperature correction and fuel cut correction may be performed.

As explained above, according to the present invention, since the single duty injector is used only during a specific pulse, there is no need to manage the flow rate characteristics over a wide range during the pulse, and the fuel injection valve can be used with high accuracy. It becomes possible to control the injection amount. Another advantage is that there is no need to read the rotational speed.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the fuel injection valve 11.1b, Fig. 2 is a diagram showing the -flL characteristics during a pulse applied to the fuel injection valve, and Fig. 3 is a diagram showing an embodiment of the present invention. Izubu II, ri diagram,
FIG. 4 is a time chart same as above. 11... Intake air amount detector 13... Integrator 1
4... Comparator 15... Monostable circuit 17...
・Applicant for fuel injection valve 1: Japan Electronics Co., Ltd. Agent: Fujio Sasashima, patent attorney

Claims (2)

[Claims] (1) An intake air amount detector that detects the amount of intake air, and a period of the fuel injection valve driving pulse is determined according to the detection signal of this intake air amount detector, and based on this period, the fuel injection valve is operated during a constant pulse. An electronically controlled fuel injection device for an internal combustion engine, comprising a drive pulse generation circuit that outputs drive pulses to a fuel injection valve. (2) The drive pulse generation circuit includes an integrator connected to the output terminal of the intake air amount detector, a comparator that compares the output of this integrator with the slice level and outputs an output at or above the slice level, and the comparator. and a monostable circuit connected to an output terminal, and the output terminal of the comparator is connected to the integrator's positive terminal. Fuel injection device.