JPS59122733A - Electronically controlled fuel injector - Google Patents

Abstract

PURPOSE:To reduce the dynamic range of an injector by making proportional control of the fuel pressure which is applied to the injection nozzle of the injector with respect to the revolution number of an engine. CONSTITUTION:The pressure of the fuel in a fuel pipe 11 is boosted in proportion to the rotational speed of an engine. A fuel pump 10 may be controlled by means of a control unit 17 via a pump driving circuit 25. Consequently, the fuel pressure which is applied to the injector 12 is controlled. The fuel pressure is detected by a fuel pressure sensor 14 which is disposed in front of a throttle 15 serving for regulating the quantity of returned fuel in a return pipe 16. The fuel pressure signal of this sensor is fed back to the control unit 17 to perform fuel pressure control. The dynamic range of the injector may be reduced apparently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection device that controls the air-fuel ratio based on engine operating parameters, and which changes the fuel pressure applied to the injection nozzle of the injector to increase the apparent dynamic range of the injector. The purpose of the present invention is to reduce the total cost of the fuel system by reducing the accuracy requirements for the injector, making the injector itself usable at low cost, and eliminating the need for a fuel regulator.

Conventionally, when constructing a twisted fuel injection system for a motorcycle engine, the dynamic range of fuel outflow is larger than that of a four-wheel vehicle, and it is difficult to maintain a flow rate accuracy of 47 (4), especially when a small flow is blocked. The same difficulty also occurs with single point injection systems for automobiles.

The present invention is an electronically controlled fuel injection device that controls the air-fuel ratio according to engine operating parameters. By providing an electronic control system that proportionally controls the F
The disadvantages mentioned in IiJ can be overcome, and the structure thereof will be explained below with reference to the embodiments shown in the drawings.

FIG. 1 shows an embodiment of the electronically controlled fuel injection system of the present invention. The intake system leading to engine 1 is 1 in the order of air inflow direction.
It consists of 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.

The fuel system consists of a fuel supply system and a return system, and the fuel in the fuel supply system is supplied to a fuel tank 71), passes through a fuel cock 8, a filter 9, and a fuel pump 10, and then is sent from the injection nozzle 13 of the injector 12 via the fuel W11. The fuel injected into the intake pipe 5 and the return system is branched from the fuel pipe 11 and sent to the fuel pressure sensor 1.
4. The water is returned to the Tsuyuel tank 7 via the throttle 15 and the return pipe 16.

Sensors that send various operating parameters to the control unit 17 include an atmospheric pressure sensor 18 and an air cleaner 2.
Intake temperature sensor 19 and throttle valve 4 provided inside
LD switch 21 detects the idling opening of the throttle valve 4.
, an intake pressure sensor 22 that detects the negative pressure in the intake pipe 5, an engine temperature sensor 23, an ignition primary voltage or crank angle sensor 24, and a fuel pressure sensor 14, etc. The control unit 17 (X) sends a drive command signal for the twerp pump 1o to a pump drive circuit 25, and a drive command signal for the injector 12 to an injector drive circuit 26.

The fuel injection in the injector 12 is performed at a crank angle of 1
Once every two revolutions, simultaneous injection is carried out in all cylinders or once in each cylinder.

gtl injector 12 is an injector drive circuit 26
The basic pulse width applied to the injector 12 is calculated in the control unit 17 based on the throttle valve opening signal from the potentiometer 20 and the engine speed signal over the entire operating range of the engine. , or the low opening range of the throttle valve 4 is calculated separately based on the intake pipe pressure signal and the rotation speed signal, and the medium and high opening ranges are calculated separately using the throttle valve opening signal and the rotation speed signal.

Correction of the flow rate fluctuation of the injector 12 due to the change in the differential pressure across the injection nozzle 13 due to the change in the intake pressure is calculated in the roll unit 17 based on the signal from the intake pressure sensor 22, and the output to the injector drive circuit 26 is corrected. It is done by doing.

In the past, the differential pressure before and after the injection nozzle 13 was kept constant through the intervention of a pneumatic regulator.

The control of the fuel pump 10 is performed in accordance with a command from the pump drive circuit 25 such that the output fuel pressure is increased in proportion to the engine speed.

Fuel pressure control will be described below.

In conventional fuel injection that synchronizes with engine rotation,
In a fuel injection system in which the fuel pressure in the fuel pipe 11 is maintained constant by a regulator, the characteristic of the basic pulse width for controlling the injector 12 is expressed by an m diagram as shown in FIG.

FIG. 6 is a rotation synchronization pulse width characteristic diagram for each engine speed under a constant fuel pressure where the injector pulse width is expressed as m5ec and the throttle valve opening is expressed as an angle or a signal voltage of the potentiometer 20.

In addition, in motorcycles with a wide rotation band and automobiles with single-point injection, a wide dynamic range of the injector's combustion fuel injection amount is required to cover the entire operating range of the engine, and in order to meet this demand, However, since it is necessary to install an attached control device, the entire Inzoecta has the disadvantage of being expensive.

The solution to this drawback is the present invention.As shown in Fig. 2, the fuel pressure is controlled in proportion to the engine speed.If the fuel pressure increases, the amount of fuel injected by injector X51 etc. increases even with the same injector pulse width. . FIG. 3 shows this relationship.

As a result, the relationship between the injector pulse width and the throttle valve opening becomes a rotation-synchronized pulse width characteristic diagram as shown in Figure 5. When the engine speed is high, a smaller injector pulse width is sufficient; A narrower dynamic range than that shown in FIG. 6 is sufficient.

As shown in FIG. 1, the control unit 17 calculates to increase the fuel pressure in the fuel pipe 11 in proportion to the engine rotation speed, and the output is applied to the twerp pump 10 via the pump drive circuit 25. The head capacity of 10 is electronically controlled and, as a result, the fuel pressure applied to injector 12 is controlled.

However, the fuel pressure is detected by a fuel pressure sensor 14 provided in front of the return amount regulating throttle 15 of the return pipe 16, and this fuel pressure signal is fed back to the control unit 17 to perform fuel pressure control.

A block line 1 of the fuel pressure control system is shown in FIG.

The return system is a system that prevents an abnormal increase in the fuel pressure in the fuel pipe 11 due to sudden changes in engine speed, etc., and returns excess fuel to the fuel tank 7 via the return pipe 16, thereby preventing an excessive amount of fuel from being returned. For this purpose, an aperture 15 is installed.

The present invention is comprised of ht as described in the claims, and is an electronic control system that proportionally controls the fuel pressure applied to the injection nozzle of the fuel unit fuel injector with respect to the rotational speed of the engine. It is an electronically controlled fuel injection device with High processing accuracy is not required, the injector can be made at low cost, and the driving power of the twerp pump can be reduced when the engine is running at low speed.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a fuel injection system showing an embodiment of the present invention, Fig. 2 is a fuel pressure-engine speed diagram, Fig. 3 is an injector injection amount-injector pulse width diagram, and Fig. 11 is a fuel pressure control system. Fig. 5 is a diagram showing the relationship between the injector pulse width and throttle bulge opening according to the engine speed of the embodiment, and Fig. 6 is the injector pulse width according to the engine speed under constant fuel pressure of the conventional example. - Throttle valve opening relationship diagram. 1: Engine, 12: Injector, 13: Injection nozzle, 17: Funtrol unit. Patent Applicant Mikuni Kogyo Co., Ltd. Attorney: Hitoshi Kawa, Osamu Yoshaya, Fujitatsu Mushi Diagram 1? Fig. 2 (E/G rotating paddy RRM Fig. 4 Fig. 5 Throttle valve m9 poor Fig. 6 Thro) F valve open hawk

Claims (1)

[Claims] An electronically controlled fuel injection device that controls the air-fuel ratio based on engine operating parameters, characterized by having an electronic control system that proportionally controls the fuel pressure applied to the injection nozzle of the injector by a fuel injection unit with respect to the engine rotation speed. Electronically controlled fuel injection system.