JPS626094B2 - - 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 drawback 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 into a fuel supply passage 4 forming a discharge pipe.

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 bulb 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 with 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 the plurality (for example, four) of the fuel inflow chamber 20 and the fuel outflow chamber 21. Solenoid valve S ₁ ~
This partition wall 22 forms the valve seat of _S4 , and the same number of actuation starters 23a to 23d, each having a different opening area, are perforated therein.

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 interposed in the downstream chamber 26, and this keeps the flow pressure drop of the metering valve 11 at a constant value such as 0.1 kg/ ^cm2 . For example, constant pressure fuel of 2.5 kg/cm ² is supplied.

Furthermore, this pressurized fuel that has flowed into the injector 9 overcomes the elasticity of the spring 18 and pushes down the valve 15, whereby the fuel is injected in a diffusion direction of 70° to 80° and passes through the collecting portion 8. Dispersed into the air stream. In this case, the opening amount of the injector 9 can be varied according to the fuel flow rate, and fuel can be injected in an amount that varies over a wide range. Moreover, due to the action of the compression spring 18, the injector 9 has good responsiveness to increases and decreases in fuel.

Here, a metering operation signal from a computer 19 attached to the engine is applied to each of the solenoid valves S ₁ to _{S 4} .
In addition to inputting the FM signal of the intake air flow rate value output by the air flow sensor 28 attached to the intake pipe 7, engine operating elements other than the intake air flow rate, such as cooling water temperature, engine output, acceleration/deceleration, exhaust gas component amount, etc. An electrical signal from the sensor 29 is input.

The operation of this computer 19 will be explained below, but the premise is that if the area of the operating opening 23a of the solenoid valve S ₁ is A, then the openings 23b, 23c of the solenoid valves S ₂ , S ₃ , and S ₄ are ,23
The area of d is set to 2A, 4A, and 8A, and therefore, the open circuit area as the metering valve 11 is variable, that is, the operating area when only valve S ₁ is opened. A is the minimum, and
Operating area when all valves S ₁ to _{S 4} are open: 15
A is the maximum, and an arbitrary open circuit area of 2A to 14A can be formed in between by combining the opening valves.

Moreover, the signal system of the metering operation signal employs a system in which DC current is supplied for a constant time period T within each period of the operation frequency (the definition will be described later).

By the way, as illustrated in the metering characteristic table in FIG. 3, the intake air flow rate value output from the sensor 28 is
A signal system is adopted in which the output frequency o of the FM signal is 40 Hz at the minimum flow rate and 1500 Hz at the maximum flow rate.

Therefore, in this computer 19, the sensor 2
In response to the air flow rate signal o input from 8,
Classification is performed based on the maximum motion range stored in advance. For example, if o = 240Hz, the operating range is found, the selected frequency division ratio is set to 1/3, and the solenoid valve to be operated is 2 of valve S ₁ and valve S ₂
Select individually.

Based on this selection, the output signal o is divided by 1/3 to transform it into an operating frequency of =80 Hz, and during each period, T timed operating current is applied to valves S ₁ and S ₂ .

Due to this energization, the metering valve 11 has a flow rate of 3A×T (comparison unit) per 1Hz,
That is, a flow rate of 240 A×T per hour is metered, and in this way, a fuel flow rate that exactly corresponds to the intake air flow rate is metered.

In addition, in the above-mentioned basic operation of the computer 19, the fuel injection flow rate is always made proportional to the intake air flow rate to maintain the air-fuel ratio of the mixture at a constant rate, but as is well known, it depends on the operating state of the engine. In the end,
It is better to temporarily raise or lower the air-fuel ratio to properly maintain the combustion operation of the engine, and for the purpose of adapting to this, the computer 19 receives the detection signals of the various operating elements described above. If the input element value goes outside the preset range, the time limit value T of the actuation signal is increased or decreased accordingly, thereby temporarily increasing the adjustment amount, or It is working to lower it.

The feeding device of the embodiment that operates in this manner has the following excellent characteristics.

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

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

(c) Since the metering valve 11 has no mechanical parts, it has good operational responsiveness and metering accuracy, and since it is used in combination with a simple solenoid valve, it is inexpensive and has fewer failures.

(d) Since the FM signal and its frequency-divided signal are used for metering control, precise control over a wide range of flow rates is possible, and the burden on the computer 19 is simplified, making the computer less expensive.

(e) Normal and smooth operation of each part of the engine is always maintained in response to changes in engine operating conditions.

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, and also has a simple function. Since the computer is configured to perform metering appropriate to each operating condition, it is possible to stably generate an appropriate mixture, and an inexpensive supply device is obtained.
This has the effect of improving the practicality of the injection fuel supply device.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a fuel supply system for an internal combustion engine showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the injector shown in Fig. 1, and Fig. 3 is a metering characteristic of the embodiment device. FIG. ...Operating period as a minute period, o...FM signal period, _S1 to _S4 ...Solenoid valve, 2...Pump, 4,
DESCRIPTION OF SYMBOLS 10...Supply passage, 7...Intake pipe, 8...Collection part, 9...
Injector, 11...Metering valve, 12
...Differential pressure regulator, 19...Computer, 23
a to 23d...operation open circuit, 28...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 combination 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 interposed in the middle of the supply passage. Furthermore, in response to the FM signal of the intake air flow rate value electrically output by the air flow sensor attached to the intake pipe, a fuel flow adjustment operation signal is applied to each of the above solenoid valves to obtain the required air-fuel ratio. The computer is provided with a computer for controlling the metering operation signal as a command signal for opening a constant time period in each cycle of the selected frequency division ratio of the FM signal, and for controlling its use in accordance with the fuel flow rate value. 1. A fuel supply device for an internal combustion engine, characterized in that a frequency division ratio to be selected and a solenoid valve to be opened are selected, thereby continuously injecting a desired flow rate of fuel into an intake air flow in an intake pipe.