JPS581674Y2 - Diaphragm fuel pump with backflow prevention device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a so-called paper return type diaphragm fuel pump in which a return pipe for paper return is opened in the upper part of the discharge chamber. The present invention relates to a diaphragm fuel pump with a backflow prevention device that prevents flow from flowing into the carburetor side through a pipe.

One of the most problematic issues in fuel delivery systems for internal combustion engines is the use of fuel paper.

This means that the fuel is heated by the heat generated by the engine, and a portion of the fuel vaporizes to become fuel in a gas-liquid mixed state.

Formation of fuel into paper causes paper lock within the fuel pump, which not only impedes fuel delivery but also increases fluctuations in discharge pressure.

Furthermore, when the paper is sent to the carburetor, the air-fuel ratio is disturbed, which can cause engine malfunction.

One of the means to prevent paper from being sent to the vaporizer is a return system.

(Utility Model Publication No. 16-12272, Utility Model Application No. 51-11380
No. 2) This method returns the paper in the fuel to the fuel tank, and there are two types: an in-line type in which a return passage and a paper separator are provided in the discharge passage between the fuel pump and the carburetor, and one in which paper in the fuel is returned to the discharge chamber of the fuel pump. It is divided into an in-pump type that opens a passage.

On the other hand, in order to prevent fuel from the fuel tank from flowing into the carburetor via the return passage when the vehicle rolls over, a check valve must be provided in the return passage, if necessary.

However, the return passage is usually constituted by a pipe, and it is difficult to provide a check valve within the pipe.

Additionally, installing a check valve in a narrow return pine requires the use of a very small check valve, which increases the flow resistance of the paper flowing through the return pipe.

Originally, it is best to use a check valve that has low flow resistance in the 4dll direction and opening characteristics, and that can reliably prevent backflow.
The smaller the device, the more difficult it is to manufacture it.

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-pump paper return type diaphragm fuel pump with a backflow prevention device that allows installation of a large check valve. This will be explained in detail.

Referring to FIG. 1, an outer casing 5 is fastened to a flange 2 of a die-cast lower body 1 while holding a diaphragm 3 and a separator 4 therebetween.

The separator 4 and the outer casing 5 are each formed by drawing a thin metal plate, and the outer casing 5 has three cylindrical parts 51, 52, 52, 52, 52, 50, 50, 50, 50, 50, 50, 50, 50, 50, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 25, 22, 25, 22, 22, 22, 22, 22, 2, 2 that that that the separator 4 and the outer casing 5, respectively, are drawn.
It has 53.

The separator 4 is provided with an intake valve 6 and a discharge valve 7, and an intake chamber 8 is provided covering the intake valve 6.

The suction vibrator 9 penetrates the outer casing 5 and the intake chamber 8 and opens into the suction chamber 10, and the discharge vibe 11 penetrates the second cylindrical part 52 of the outer casing 5 and opens at the lower part of the discharge chamber 12. are doing.

The J-turn vibe 13 has a jet 14 inside, which opens into a valve chamber 15 formed by recessing the top surface 54 of the outer casing 5 .

The valve chamber 15 has a diameter larger than that of the return vibe 13, and a check valve 16 is provided in the valve chamber 15.

The check valve 16 allows fuel to flow from inside the discharge chamber 12 to a fuel tank (not shown), and prevents flow from the fuel tank to the discharge chamber 12 side.

Since the present invention is constructed as described above, it operates as follows.

The paper accumulated in the upper part of the discharge chamber 12 is transferred to the valve chamber 15 through the check valve 16, and returned to the fuel tank in a measured amount by the jet 14 of the return vibe 13.

Now, if the vehicle rolls over and the position of the fuel tank becomes higher than the position of the discharge chamber 12, the fuel in the fuel tank attempts to flow back into the discharge chamber 12 via the return vibe 13.

However, since check valve 16 is closed, backflow of fuel is prevented.

In the above operation, the check valve 16 is provided in the valve chamber 15 with a diameter larger than that of the return vibrator 13, so the check valve 16 can be made large, and has low opening characteristics and flow resistance. It is possible to set up something.

Furthermore, since the structure is such that the check valve 16 is installed inside the discharge chamber 12, the structure is simplified compared to a structure in which a large check valve is installed in the middle of the return vibe 13. Does not adversely affect layout.

The above is one embodiment of the present invention, and the present invention is not limited to the above embodiment.

For example, in a diaphragm fuel pump in which a suction chamber and a discharge chamber each protrude into a cylindrical shape, a check valve is provided inscribed in the discharge chamber, and a return vibe is opened above the check valve. This configuration is also one of the embodiments of the present invention.

Furthermore, as shown in FIG. 2, the vicinity of the opening of the return vibe 13' is expanded to a large diameter to form a valve chamber 15'.
It is also possible to have a structure in which a check valve 16' is provided at 5'.

Note that the type of check valve is not limited to the seven-umbrella type valve described above, and a reed valve may also be used.

As described above, according to the present invention, in a paper return type fuel pump, it is possible to prevent backflow of fuel without impairing the paper return characteristics, and it is possible to effectively prevent rollover and prevent paper lock. It is.

Furthermore, since the valve chamber and check valve are provided inside the discharge chamber, the engine is simplified and the layout is not adversely affected.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view of essential parts showing another embodiment of the present invention. 12...Discharge chamber, 13...Return vibe, 15.
... Valve chamber, 16... Check valve.

Claims (1)

[Scope of utility model registration request] In a diaphragm fuel pump that returns paper by opening a return pipe at the top of the discharge chamber, a valve chamber with a larger diameter than the return pipe is formed at the top of the discharge chamber.
A diaphragm fuel pump with a backflow prevention device, characterized in that a return pipe is opened in the valve chamber, and a check valve is provided in the valve chamber to prevent backflow from the return pine side to the inside of the discharge chamber.