JPS6155609B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply device for an internal combustion engine for generating a mixture of intake air for a spark ignition fuel injection engine mainly used in automobiles.

Unlike the negative pressure suction carburetor system that has been widely used in the past, this type of fuel injection engine actively supplies pressurized fuel to the intake system, so the amount of fuel supplied can be controlled at will. This makes it possible to obtain an appropriate air-fuel mixture under various operating conditions of the engine, and as a result, it has excellent characteristics that allow stable combustion operation of the engine to be maintained.

However, in the fuel supply system of a fuel injection engine, it is essential to add a control mechanism for the injection flow rate. In addition, an injection nozzle is provided for each cylinder due to insufficient air-fuel mixture distribution, which also has the disadvantage of making the fuel supply system more complicated and expensive. Yes, as a result,
Currently, cars equipped with fuel injection engines are limited to race cars and some luxury cars, and are not widely used in general private cars.

The present invention was made in view of the current situation, and the proposed technology adopts a method of continuously injecting fuel into the gathering part of the intake pipe, and also uses a metering method to control the injection flow rate. The purpose of the present invention is to provide a fuel supply system for a fuel-injected internal combustion engine that is simple in structure, inexpensive, and highly practical. It is about providing.

The present invention will be described below based on an illustrated embodiment.

In the configuration of the supply device of the embodiment, as shown in FIG. 1, a return valve 3 that opens at a constant pressure is provided between the discharge side of a fuel pump 2 connected to a fuel tank 1 and the tank 1. The same pump 2
Fuel pressurized to a constant pressure is discharged from the discharge pipe into the fuel supply passage 4.

On the other hand, a fuel injector 9 is attached to the peripheral wall of the gathering part 8 of the intake pipe 7 of the engine 6.
Furthermore, a metering valve 11 and a differential pressure regulator 12 are interposed in parallel between a fuel supply passage 10 connected to the injector 9 and the supply passage 4.

As shown in FIG. 2, the injector 9 is formed of a body 13, a nozzle 14 fixed to the lower part of the body 13, and a hemispherical valve 15 that abuts the lower surface of the nozzle jet 14a. Further, the valve 15 is held at the lower end of an umbrella-shaped retainer 17 by an adjustment nut 16, and the retainer 17 is held by the elasticity of a compression spring 18 interposed between it and the bottom of the nozzle 14. Since it is pushed up, the valve 15 is pressed against the lower surface of the jet 14a at a constant pressure.

Next, the metering valve 11 is formed with a fuel inflow chamber 20 and a fuel outflow chamber 21, and the partition wall 22 is connected to each of a plurality of (five) solenoid valves attached to the inflow chamber 20. 23A, 23
The same number of operating openings 24A, 24B ₁ to 24B ₄ , _each having a different opening area _, are bored in the partition wall 22.

Further, the differential pressure regulator 12 is formed of diaphragm equilibrium pressure chambers 25 and 26 that communicate with the upstream and downstream sides of the metering valve 11, and
A balance spring 27 is mounted in the downstream chamber 26, so that the flow pressure drop of the metering valve 11 is maintained at a constant value, for example, 0.1 kg/cm ² . For example, 2.5Kg/
A constant pressure fuel of cm ² is supplied.

Here, as the fuel injector, in addition to the injector 9 having the above-mentioned structure, as shown in FIG. The shaped valve 30 is pressed against the lower surface of the jet 31a of the nozzle 31 by the elasticity of the spring 28.

Therefore, the fuel that has flowed into the injectors 9, 29 is caused by the spring 18, at the constant pressure (2.5 kg/cm ² ).
28, the valves 15, 30 are pressed down, whereby the fuel is injected in a diffusion direction of 70° to 80° and is atomized into the air flow passing through the collecting portion 8.

Although the injectors 9 and 29 are arranged upstream of the throttle valve 32, they can also be mounted downstream of the throttle valve 32 if necessary.

Next, each solenoid valve 23A, 23B ₁ to 23
A metering operation signal output from a servo signal generation circuit 34 of a computer 33 attached to the engine is applied to the solenoid _B4 . Signal input circuit 35 and arithmetic circuit 3
6 is provided.

Therefore, the engine operating element signal input circuit 35
, an air flow sensor 3 attached to the intake pipe 7
In addition to inputting the output signals of 7, engine speed, engine temperature, throttle valve opening,
Element sensor 3 as required, such as the amount of exhaust gas components
8 output signals are input.

Here, the operation of the arithmetic circuit 36 will be explained. As a premise, the metering operation of the metering valve 11 will be explained using an example shown in the table of FIG. 4.

Five solenoid valves 2 equipped with valve 11
3A, 23B ₁ to 23B ₄ are all valves that operate on and off, but among them, one specific valve 23
A is a duty control valve, i.e.
Operates on for a selected time period within a cycle time of 100msec,
The time limit can be selected from 64 levels with a minimum of 10 msec, a maximum of 90 msec, and an interval of 1.25 msec.

In addition, the other parallel valves 23B ₁ to 23B ₄ have an area ratio between the open circuits 24B ₁ to 24B ₄ as follows.
The values are set to be larger in series, and only the valves selected in combination are continuously turned on.

The open circuit area of the duty valve 23A is set to be slightly larger than the open circuit area of the minimum open circuit valve _23B1 .

With such a solenoid valve configuration, the entire metering operation range of the valve 11 is divided into 16 operating ranges, and 1024 steps (64 x 16) can be achieved by selectively driving the valve corresponding to each operating range. Continuous adjustment amount can be obtained.

Therefore, the method of the actuation signal applied to each solenoid from the servo signal generation circuit 34 is a DC pulse with a selected width for the duty valve 23A, and a DC pulse with a selected width is applied to the duty valve 23A. On the other hand, it is a direct current signal.

By the way, the arithmetic circuit 35 stores the optimum air-fuel ratio corresponding to the operating state of the engine based on data determined from design and experiments, and when the circuit is in operation, input values from the element sensors 37 and 38 are stored. The above air-fuel ratio is determined based on, and further,
A required fuel flow rate value is calculated by multiplying the determined air-fuel ratio by the intake air flow rate, which is the input value of the sensor 37,
The flow rate value is sent to the signal generation circuit 34.

Next, the generation circuit 34 determines the operating range ~ and the duty stage based on the flow rate value, and outputs an operating signal corresponding to the operating range and stage to the metering valve 11.

As a result of this operation, the injectors 9 and 29 inject pressurized fuel adjusted to be equal to the flow rate value, and a mixture of air and fuel having the required air-fuel ratio is generated.

The feeding device of this embodiment has the following excellent characteristics.

(a) Since a single injector 9, 29 is provided in the intake pipe gathering part 8, the structure is simple and there is only one injector to the intake pipe.
Only one injector needs to be installed, so the injector can be installed at an ideal position relative to the intake air flow.

(b) Since the air-fuel mixture is generated by continuous injection from the injectors 9 and 29, a stable air-fuel ratio can be obtained.

(c) Since the metering valve 11 has no mechanical parts, the metering operation has good responsiveness and metering accuracy, and since it is used in combination with a simple solenoid valve, it is inexpensive and has fewer failures. Moreover, all fuel flow rates can be adjusted by simply operating each solenoid valve in the metering valve as a duty valve or a valve that selectively operates on and off, simplifying the structure.

(d) Since duty control is performed for metering, precise control over a wide range of flow rates is possible, and the functions burdened by the computer 15 are simplified, making the computer inexpensive.

(e) When the injector 9, 29 is installed upstream of the throttle valve 32, the solenoid valve 2
Periodic fluctuations in the supplied air-fuel mixture based on the 3A duty control are averaged out, improving the smoothness of engine operation.

(f) When the injectors 9 and 29 are provided on the downstream side of the throttle valve 32, good atomization improves distribution, and responsiveness during sudden acceleration and deceleration operations becomes faster.

As described above, according to the fuel supply device for an internal combustion engine according to the present invention, the pressurized fuel is metered by the combined operation of the solenoid valve, and then continuously injected at the gathering part of the intake pipe. Since the computer is configured to adjust the amount of fuel suitable for each operating condition, it is possible to stably form an appropriate air-fuel mixture, and an inexpensive supply device is obtained. It has the effect of improving.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fuel supply system for an internal combustion engine showing one embodiment of the present invention, FIG. 2 is an enlarged sectional view of the injector shown in FIG. 1, and FIG. 3 is an injector showing another embodiment. FIG. 4 is an enlarged cross-sectional view of the metering valve. 2... Fuel pump, 4, 10... Supply passage, 7
... Intake pipe, 8 ... Collection part, 9, 29 ... Injector, 11 ... Metering valve, 12 ...
Differential pressure regulator, 23A...Specific solenoid valve, 23B ₁ to 23B ₄ ... Parallel solenoid valve, 3
2...Throttle valve, 33...Computer, 3
4... Servo signal generation circuit, 37... Flow sensor.

Claims (1)

[Claims] 1. Providing a supply passage that guides the fuel discharged at constant pressure from the fuel pump to a single fuel injector with a constant opening valve pressure disposed at the gathering part of the intake pipe,
A metering valve, which is formed by a composite of a plurality of solenoid valves each having a different on/off operation opening area, and whose flow pressure drop is kept constant by a differential pressure regulator, is installed in the middle of the supply passage. death,
Furthermore, a computer is provided that calculates a fuel flow rate value for obtaining a predetermined air-fuel ratio based on at least a detected value of the intake air amount among operating elements of the engine, that is, an element signal electrically output from an air flow sensor attached to the intake pipe. At the same time, a duty unit is provided which instructs one specified solenoid valve to open at a predetermined time limit within each cycle time by sending an operating signal corresponding to the above-mentioned flow rate value output from the servo signal generation circuit of the computer. Apply as an actuation signal,
In addition, a continuous opening command signal is applied to the parallel solenoid valves other than those specified by selective opening operation in combination, so that the required flow rate of fuel is continuously injected into the intake air flow in the intake pipe. A fuel supply device for an internal combustion engine, characterized by: