JPS59122734A - Electronically controlled fuel injector - Google Patents

Abstract

PURPOSE:To constrict the dynamic range of an injector by controlling the fuel pressure which is applied to the injection nozzle of the injector in relation to the revolution number of an engine and the suction pressure signal. CONSTITUTION:A control unit 18 receives a variety of operating parameters from a suction air differential pressure sensor 23, a crank angle sensor 24 and so on. The operation of an electronic control valve 16 which determines the quantity of returned fuel is performed via an electronically controlled valve driving circuit 28 on the basis of the arithmetic operation of the control unit 18 which is performed by the differential pressure detecting signal fed back from a fuel differential pressure sensor 26. By controlling the fuel pressure on the bases of the data of the engine's revolution number and suction pressure, the flow-rate dynamic range of the injector may be constricted apparently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection device that controls the air-fuel ratio in relation to the operating parameters of an engine. It is an object of the present invention to provide a fuel injection system that can reduce fuel injection, reduce the accuracy required for an injector, and reduce the cost of the entire system.

Conventionally, when configuring a fuel injection system for a motorcycle engine, it is necessary to
The dynamic range for controlling the fuel flow rate is larger than that of four-wheel vehicle engines, and there is a problem in that it is difficult to ensure accuracy in the flow of fuel, especially when the fuel flow is small, such as when idling or at low speeds. The same problem exists in single-point injection in automobile engines as well.

The present invention is an electronically controlled fuel injection device that controls the air-fuel ratio in relation to engine operating parameters. The dynamic range is apparently reduced, and the problems mentioned above can be overcome.The structure will be explained below with reference to the embodiments shown in the drawings.

FIG. 1 shows an embodiment of the configuration of an electronically controlled fuel injection system according to the present invention. The air system leading to the engine 1 includes, in order of the air inflow direction, an air cleaner 2 opened to the atmosphere, a surge tank 3 provided after the air cleaner 2, a throttle valve 4, an intake pipe 5, and an intake valve 6. Also eye 1
1. An air bypass passage 7 is provided to bypass the front and rear of the throttle valve 4, and the air bypass passage 7 is provided with an adjustment screw 8 for adjusting the amount of bypass air.

The fuel system consists of a fuel supply system and a return system.
Fuel for the fuel supply system is supplied from the Tsuyuel tank 9,
Fuel cock 10, filter 11, fuel pump 1
Injection of the injector 14 via the fuel pipe 13 via the
The fuel injected into the intake pipe 5 by the nozzle 15 is branched from the fuel pipe 13, and is returned to the fuel tank 9 via the electronic control valve 16 and the return pipe 17.

Sensors that send various operating parameters to the control unit 18 include an atmospheric pressure sensor 19 and a surge tank 3.
Intake temperature sensor 20 and throttle valve 4 provided inside
1, which detects the idling opening of the throttle valve 4, and the D switch 2.
2. An intake air differential pressure sensor 23 that detects the differential pressure of one intake air after RiJ of the throttle valve 4, a sensor 24 that detects the ignition primary pressure or crank angle, an engine wetness sensor 25, the fuel pressure of the fuel pipe 13 and the intake air. Each sensor is provided as a fuel differential pressure sensor 26 that detects the differential pressure with the intake pressure in the pipe 5, and each operating parameter signal from each sensor is sent to the control unit 18 described in 1lfJ. A drive command signal is sent to the fuel pump 12 via the relay 21, a drive command signal is sent to the electronic control valve 16 that controls the return amount of fuel via the electronic control valve drive circuit 28, and a drive command signal is sent to the injector 14 via the injector drive circuit 29. A pulse width signal is sent to the gate to control its opening and closing.

The injector 14 injects fuel to all cylinders simultaneously or independently to each cylinder with a predetermined pulse width once every one revolution or every two revolutions of the crank angle according to a command from the control unit 18.

The operation of the electronic control valve 16 that regulates the return amount of fuel is as follows:
Based on the calculation of the control unit 18 based on the differential pressure detection signal fed back from the fuel differential pressure sensor 26,
This is done via the electronic control valve drive circuit 28.

The control unit is an 18Hr Zotal computer.

The engine temperature sensor 25 detects a temperature selected from appropriate temperatures such as cylinder cooling water temperature, oil temperature, cylinder head wetness, flag seat wetness, etc.

FIG. 5 is a block diagram of the aforementioned fuel system and its control system.

As shown in the figure, the fuel system is branched into a fuel flow from the fuel tank 9 to the filter 11 to the fuel pump 12 to the injector 14, and a return fuel flow from the fuel pump 12 to the electronic control valve to the fuel tank 9. The fuel differential pressure sensor 26 may be provided on any of the fuel pipes immediately after the fuel pump 12.

As for the flow of electrical signals, detection signals such as a fuel differential pressure signal from a fuel differential pressure sensor 26, an intake pressure signal, and a 1 rotation speed signal are manually inputted to the control unit 18, and the calculation output of the unit 18 is sent to an electronic control valve drive circuit 28. The fuel is transmitted to the injector 14 via the electronic control valve 16 that controls the fuel return 6i and the injector drive circuit 29.

As shown in FIG. 2, which will be described later, the control unit 18 sends a control signal to the electronic control valve 16 for return amount control so as to perform fuel pressure control that increases the fuel pressure difference across the nozzle as the engine speed increases. Output.

The twerp pump 12 is driven under a constant voltage, and is driven so as to maintain a constant lifting capacity.

The electronic control valve 16 for controlling the return amount is composed of a solenoid valve or a motor-driven IJ near control valve whose flow path area is continuously variable.

Next, the operation of the present invention will be explained.

In conventional fuel injection devices, the fuel pressure in the fuel pipe 13 is kept constant using a pneumatic regulator.
Fuel injection is performed in synchronization with the engine rotation at a predetermined position in the engine rotation angle, but when operating to maintain the air-fuel ratio at a constant value, the basic pulse width characteristic that governs the opening and closing of the injector 14 is It is represented as a diagram as shown in the figure. FIG. 5 shows rotation synchronization P/l and S width characteristics, which are obtained as ih of injector pulse width versus throttle valve opening for each engine speed at constant fuel pressure.

The injector pulse width is m Sec, and the throttle valve opening is expressed by the opening angle or the voltage of a potentiometer that indicates the opening.

For example, the pulse width at 8000 rpm is l+m5ec
It is necessary to provide stable and highly accurate fuel supply between ~l 1 m5ec, but in reality, in order to ensure maximum flow rate, fuel supply during small pulse widths, that is, small flow rates, is In the past, accuracy was not always a concern,
Especially rotation/-? Motorcycle engines with a wide range of pressure and single-point injection engines in automobiles require a fuel injector with a wide fuel flow control range, that is, a wide flow dynamic range. In the present invention, the fuel pressure applied to the injector 14 is controlled to a value that appears on the control surface as shown in FIG. 2, for example. Although the zero intake pressure is always a negative value, the relationship between the differential pressure before and after the nozzle 150 of the injector 14, the twisting pressure, and the intake pressure is determined by the following equation. That is, nozzle tJiJ
Rear differential pressure - fuel pressure - expressed as a plane tilted toward the origin of atmospheric pressure.

By controlling the differential pressure across the nozzle of the injector 14 to a low pressure when the engine speed is low, as shown in Figure 1g2, the pulse width characteristics that drive the opening and closing of the injector 14 can be changed to the line shown in Figure 14. Represented as a diagram. As is clear from this figure, compared to the case where the fuel pressure is constant in Figure 5, it is possible to narrow the injector pulse width at the position where the throttle valve opening is large, and the fuel pressure can be controlled by the engine speed signal and the intake pressure. By performing arithmetic control in the control unit based on the signal, it is possible to make the injector's flowmeter dynamometer apparently smaller than that shown in Fig. 5. Therefore, it is possible to use an inexpensive injector whose accuracy is not very good. is now possible.

The nozzle differential pressure of the injector is controlled by, for example, keeping the lift capacity of the twerp pump constant and electronically controlling the return stroke of the fuel.

The present invention has the structure described in the claims, and is an electric f-control fuel injection device that controls an air-fuel ratio in relation to an engine operation/(' parameter), which is controlled by a control unit. The fuel pressure applied to the injection nozzle of the injector is calculated in relation to the engine rotational speed signal and the intake pressure signal, and the change is controlled. By controlling the fuel differential pressure to a large value, the dynamic range of the injector can be reduced in appearance, so even if an injector with low accuracy is used, the accuracy of fuel flow control during small flow peaks can be increased. This has made it possible to reduce the cost of injectors, and in particular has had the effect of greatly reducing the cost of single-point injection fuel injection systems for motorcycle and four-wheel vehicle engines. It is something that

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing an embodiment of the present invention, Fig. 2 is a three-dimensional control fuel pressure diagram of a basic embodiment of fuel pressure control, Fig. 6 is a block diagram of a fuel system control system, and Fig. 1+ is an embodiment. FIG. 5 is a throttle valve opening-injector pulse width relationship diagram of a conventional example. 1: Engine, 14: Injector, 15: Injection nozzle, 18: Control unit - Patent applicant: Sankoku Kosai Co., Ltd. Agent: Kawa Umi Yoshien Fujita Tun Figure 1 □□-'' Figure 2 Figure 3 Figure 4 Slot No.

Claims (1)

[Claims] In an electronically controlled fuel injection system that controls the air-fuel ratio in relation to engine operating parameters, the fuel pressure applied to the injection nozzle of the injector is calculated by the fuel control unit in relation to the engine speed signal and intake pressure signal. An electronically controlled fuel injection device characterized in that it has an electronic control system for controlling changes.