JPH0213055Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel filter installed in a fuel system of an internal combustion engine, and more particularly to a fuel filter adapted to absorb pulsating pressure of a fuel pump.

In the fuel system of an internal combustion engine, a fuel pump sends fuel to a fuel filter, but an electric fuel pump is provided with a pulsation pressure prevention mechanism in between.

On the other hand, great efforts are made in the design of fuel supply systems for internal combustion engines to prevent fuel leakage in order to prevent danger.

Generally, fuel leakage tends to occur from joints of piping, and therefore it is important to reduce the number of joints.

However, providing a separate pulsation pressure prevention mechanism increases the number of joints in the piping, which increases the risk of fuel leakage.

In order to prevent this, a fuel filter is also known in which a bellows is provided in the fuel filter to absorb the pulsating pressure of the fuel. (Refer to Utility Model Application No. 55-62849.) However, the filter described in the above-mentioned publication has a bellows inside the filter, making it difficult to assemble, and only a small bellows can be attached, making it difficult to absorb pulsating pressure. There is a risk that it will be insufficient. Furthermore, in the method described in the above-mentioned publication, pulsating pressure acts directly on the filter body, so there is a problem in the durability of the filter body.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and provide a fuel filter that is easy to assemble, has a high pulsating pressure absorption effect, and is highly durable.

The feature of the present invention is that a filter body is provided inside the filter case, and the inside of the filter case is divided by the filter body into a downstream chamber inside the filter body and an upstream chamber outside the filter body. It has an elastic membrane that separates the fuel chamber and air chamber.

This will be explained below using figures.

FIG. 1 is a block diagram showing a fuel system of an internal combustion engine to which the present invention is applied, in which fuel in a fuel tank 1 is fed by a fuel pump 2 and passed through a fuel filter 3.
It is sent to the carburetor or injector 4 through.

Conventionally, it has been common to provide a pulsation prevention mechanism between the fuel pump 2 and the fuel filter 3, but in the present invention, the pulsation prevention mechanism is built into the fuel filter 3.

Next, a second embodiment of the fuel filter of the present invention will be described.
This will be explained using figures.

A filter body 12 made of filter paper or the like is provided inside the filter case 11, and the inside of the filter case 11 is divided into an upstream chamber 13 and a downstream chamber 14 by the filter body 12. An in-pipe 15 is inserted into the upstream chamber 13, and an out-pipe 16 is inserted into the downstream chamber 14.

The filter case 11 is formed by caulking a lid case 11A, a body case 11B, and a bottom case 11C, and an elastic membrane 17 made of a diaphragm or the like is sandwiched between the body case 11B and the bottom case 11C. This elastic membrane 17 divides the upstream chamber 13 into a fuel chamber 13A and an air chamber 13B.

Fuel supplied from a fuel pump (not shown) enters the fuel chamber 13A from the in-pipe 15, and the fuel that enters the fuel chamber 13A passes through the filter 12 to the downstream chamber 14, and then passes through the out-pipe 16. It is sent to a carburetor, etc. (not shown).

Although the fuel supplied from the fuel pump has a pulsating pressure, the pulsating pressure is absorbed by the elastic membrane 17, and the propagation of the pulsating pressure to the carburetor or the like is prevented or reduced.

FIG. 3 shows another embodiment of the present invention, in which an auxiliary case 22 is fixed to the bottom of a filter case 21. The inside of the filter case 21 and the inside of the auxiliary case 22 are communicated through a port 23. Auxiliary case 22
is divided into a fuel chamber 25A and an air chamber 25B by an elastic membrane 24 made of a diaphragm or the like. The elastic membrane 24 is provided sandwiched between the auxiliary case 22. The elastic membrane 24 is provided with a stopper 26, and the stopper 26 is provided in the air chamber 25B.
A spring 27 is provided that presses toward the 5A side.

The spring 27 assists the elasticity of the elastic membrane 24, and maintains the elastic action of the elastic membrane 24 over a long period of time, while at the same time making it possible to freely adopt an elastic modulus.

The stopper 26 prevents the elastic membrane 24 from being excessively deformed by the spring 27.
2 or the bottom surface of the filter case 21 to stop displacement.

Filter body 28, in pipe 29, out pipe 3
0 is the same as that in FIG. 2, the upstream chamber 31 communicates with the fuel chamber 25A via the port 23 to form an integrated chamber, and the downstream chamber 32 is the same as that in FIG.

In the case shown in Fig. 3 above, the pulsating pressure of the fuel is
4 and the spring 27,
This prevents or reduces the propagation of pulsating pressure to the carburetor and the like.

As explained above, the present invention provides the following effects.

Since the pulsating pressure prevention mechanism is built into the fuel filter, the number of piping joints is reduced and the possibility of fuel leakage is reduced.

Since an elastic membrane serving as a pulsation prevention mechanism is attached to the outside of the filter body, there are few restrictions on the size of the pulsation prevention mechanism, and a mechanism with a large pulsation prevention effect can be adopted.

Since an elastic membrane serving as a pulsation prevention mechanism is installed on the upstream chamber side that directly communicates with the fuel pump, pulsating pressure does not act on the filter body. Therefore, there is no decrease in the durability of the filter body.

Note that it is clear that the present invention includes various embodiments other than the above-described embodiments without changing the spirit of the present invention.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a fuel supply system of an internal combustion engine to which the present invention is applied, Fig. 2 is a sectional view showing one embodiment of the present invention, and Fig. 3 is another embodiment of the present invention. FIG. 11: Filter case, 12: Filter body, 13:
Upstream chamber, 13: Downstream chamber, 17: Elastic membrane, 21: Filter case, 22: Auxiliary case, 24: Elastic membrane.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a fuel filter installed downstream of a fuel pump in a fuel supply system of an internal combustion engine, a filter is provided in the filter case, and the filter is A fuel filter characterized in that the inside of the case is divided into a downstream chamber inside the filter body and an upstream chamber outside the filter body, and an elastic membrane is provided to divide the upstream chamber into a fuel chamber and an air chamber. (2) Registration of a utility model characterized in that the upstream chamber consists of a filter case and an auxiliary case fixed to the filter case, and an elastic membrane is provided in the auxiliary case to partition the fuel chamber and the air chamber. A fuel filter according to claim 1.