JPS62174564A - Mixture supply device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fuel injection type mixture supply device for an internal combustion engine for automobiles, and in particular to a constant pressure valve that controls the pressure of fuel sent to a fuel injection valve to a predetermined value. Regarding things that are equipped with.

<Conventional Example> In the fuel injection type air-fuel mixture supply device disclosed in Japanese Unexamined Patent Publication No. 48-44.629, a constant pressure valve is installed near the engine.

<Problem to be solved by the invention> For this reason, when the fuel pipe that sends liquid fuel to this constant pressure valve and the liquid fuel in the fuel chamber of the constant pressure valve are heated by the heat of the engine, a part of it vaporizes and the fuel pipe A paper lock phenomenon occurs inside the tank, which obstructs the flow of liquid fuel. Furthermore, fuel and its vapor are intermittently supplied into the intake passage from the fuel injection valve that injects liquid fuel, making the supply state of the air-fuel mixture unstable. An object of the present invention is to promptly return fuel vapor generated within a fuel pipe or a constant pressure valve to a fuel tank.

The purpose of this is to mount the constant pressure valve on the outer wall of the intake cylinder with the fuel chamber of the constant pressure valve facing vertically upward, and to provide a fuel return passage that returns fuel from the fuel chamber to the fuel tank. This is achieved by opening at the top of the fuel chamber.

Steam that enters from the fuel pipe or that is generated in the fuel chamber accumulates in the upper part of the fuel chamber, but when the fuel return port opens, it is immediately discharged from there into the fuel tank, preventing fuel vapor from entering the fuel passage. There is no

<Embodiment> FIG. 1 is a sectional view of a mixture supply device which is an embodiment of the present invention. A bypass passage 4 is provided in the venturi section 1 of the intake cylinder.
is open, and a heat ray sensor 5 is installed in the bypass passage 4. Two throttle valves 2.3 are installed below the venturi section.

A jet port of a fuel injection valve 6 is open downstream of the throttle valve 2 . Further, a pressure passage 8 is opened between the throttle valve 2 and the jet nozzle, that is, at a portion representing the pressure of the jet nozzle, and a constant pressure valve 9 that introduces negative pressure through this pressure passage 8 is installed outside the upper part of the intake cylinder. It is installed on the side. Needless to say, the intake cylinder communicates with each cylinder via the intake manifold. The constant pressure valve 9 has a diaphragm 13 sandwiched between a valve body 11 and a cover 12, and a pressurized fuel chamber 15 and a pressure chamber 16.
The pressurized fuel chamber 15 has a leak pipe 17 connected to its upper surface, and a fuel introduction pipe 19 and a fuel delivery pipe 10 connected to its side surface. A pressure passage 8 provided in the intake cylinder communicates with the pressure chamber 16, and a coiled spring 4 is installed between the plate attached to the adjustment screw and the center of the diaphragm 13.

When the engine starts and intake air flows into the intake cylinder, a portion of the intake air also flows into the bypass passage 4 opened to the venturi portion 1, and the hot wire sensor 5 detects the air flow rate. The hot wire sensor 5 heats, for example, a tungsten wire filament by passing a current through it, and is maintained at a constant temperature by power from a control unit (not shown). Since the amount of heat removed from the hot wire sensor 5 differs depending on the amount of air flowing through the bypass passage 4, the electric power required to maintain the temperature at a constant temperature changes.

The control unit processes this change in power and controls the fuel injection valve 6.
generates an output signal that controls the valve opening time of the valve. Furthermore, when intake air flows into the intake cylinder, negative pressure is generated downstream of the throttle valve 2, reducing the pressure in the pressure passage 8 and the pressure chamber 16 of the constant pressure valve 9. therefore.

The diaphragm 13 is pulled down toward the pressure chamber 16 against the spring force of the spring 14, and the volume of the pressurized fuel chamber 15 increases. Liquid fuel pressurized by the fuel pump and passed through the filter flows into the pressurized fuel chamber 15 from the fuel introduction pipe 19, but excess liquid fuel is returned to the fuel tank through the leak pipe 17, so the constant pressure valve 9 It becomes possible to supply liquid fuel at a predetermined pressure to the fuel injection valve 6 and inject fuel in proportion to the valve opening time.

The air-fuel mixture supply device of this embodiment configured as described above has a compact structure without requiring a metal fitting to support the constant pressure valve as in the prior art, since the constant pressure valve 9 is attached to the upper part of the intake cylinder. Further, the fuel delivery pipe 10 is shortened without requiring a long pressure passage pipe unlike the conventional one.

This reduces pipe installation work time and
The proportion of fuel vapor generated by heating the fuel delivery pipe 10 is reduced. Furthermore, the steam generated in the fuel delivery pipe 10 rises and accumulates in the pressurized fuel chamber 15 of the constant pressure valve 9 installed above the fuel injection valve 6.
When the pressure exceeds a certain level, a gap is formed between the lower end of the leak pipe 17 and a seat provided at the center of the diaphragm 13, and this gap flows out through the leak pipe 17 into the fuel storage tank. Therefore, during constant speed operation, only liquid fuel at a constant pressure is always injected from the fuel injection valve 6.
The air-fuel ratio of the mixture is stably controlled.

In addition, since the opening of the pressure passage 8 is located in the center near the throttle valve 2 and directly above the injection port of the fuel injection valve 6, pressure fluctuations near the injection port are immediately transmitted to the pressure chamber 16 of the constant pressure valve 9. be done. Therefore, the pressure applied to the liquid fuel in the fuel delivery pipe IO during acceleration and deceleration is changed in proportion to the pressure near the jet nozzle, so as the pressure near the jet nozzle fluctuates, the trout also follow the valve opening time. It is possible to supply an amount of fuel proportional to the amount of fuel.

FIG. 2 is a plan view of the air-fuel mixture supply device shown in FIG. 1, and FIG. 3 is a front view of FIG. 2. The same parts as in FIG. 1 are given the same reference numerals, but the electrical control system not shown in FIG. 1 is also shown, and the control unit 20 shown in the upper left of FIG. It is connected to the fuel injection valve 6 by a conductive wire 22, and is also connected to a hot wire sensor by a conductive wire 22. The constant pressure valve 9 is attached to the upper side of the intake cylinder, the leak pipe 17 is attached to the upper part, and the fuel delivery pipe 10 is attached to the side. In FIG. 3, the constant pressure valve 9 is not shown because it is located behind the intake cylinder.

In the conventional air-fuel mixture supply device, the constant pressure valve 9 was held by a metal fitting attached to the intake cylinder, so it was separated from the intake cylinder, and the fuel delivery pipe IO connected to the constant pressure valve 9 was also long, giving it a more complicated appearance. However, in this device, the fuel delivery pipe 10 is shortened.

As described above, the air-fuel mixture supply device of this embodiment has the effect that by fixing the constant pressure valve to the outside of the upper part of the intake cylinder, it is possible to stably supply a fuel amount proportional to the intake air amount from the fuel injection valve. .

In the above embodiment, the intake air amount is detected by installing the hot ray sensor 5 in the bypass passage, but it is better to directly measure the intake air amount by installing the hot ray sensor on the intake path of the intake cylinder without providing a bypass passage. . Further, the intake air amount detection means does not use a heating wire method, but has the effect that an accurate fuel amount proportional to the detection can be supplied from the fuel injection valve.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a mixture supply device that is an embodiment of the present invention, FIG. 2 is a plan view of a carburetor equipped with the mixture supply device of FIG. 1, and FIG. 3 is a front view of FIG. 2. It is a diagram. 4... Bypass passage, 5... Heat ray sensor, 6...
Fuel injection valve, 8... Pressure passage, 9... Constant pressure valve, 10
...Fuel supply 2nd 3rd cause

Claims (1)

[Claims] 1. It is equipped with a fuel injection valve that supplies an amount of fuel into the intake cylinder according to the amount of air taken into the intake cylinder, a fuel chamber and an air pressure chamber that are partitioned by a diaphragm, and a fuel introduction passage from the fuel pump. Depending on the pressure difference between the pressure of the fuel led to the fuel chamber through the fuel chamber and the air pressure in the air chamber, the opening and closing of the fuel return passage from this chamber to the fuel tank is controlled via the fuel return passage to control the opening and closing of the fuel return passage. and a constant pressure valve configured to maintain the pressure of fuel supplied to the fuel injection valve at a predetermined value by controlling a return amount, wherein the constant pressure valve is configured such that the fuel chamber is vertically upward. An air-fuel mixture supply device characterized in that a pressure valve is fixed to an outer wall of the intake cylinder and the opening of the fuel return passage is opened at the upper part of the fuel chamber.