JPS621491Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a diaphragm made by bonding a synthetic resin film and a rubber member, and its purpose is to prevent warping of the diaphragm during molding and operation.

Usually, the diaphragm is made of full rubber or a composite of base fabric and rubber. This rubber material can be used depending on the environment in which it is used. However, depending on the usage environment, it may not be possible to cope with the selection of rubber materials alone. For example, nitrile rubber and hydrin rubber have been used as rubber materials for places affected by gasoline, but in recent years alcohol has been mixed with gasoline. It has also been pointed out that the above-mentioned rubber materials cannot withstand alcohol-containing gasoline and sour gasoline, as peroxides are generated in gasoline during driving and become sour gasoline. As a countermeasure to this problem, some attempts have been made to use a resistant synthetic resin film on the surface of the diaphragm.

Compression molding is generally used as a means for joining a synthetic resin film and a rubber member. That is, a resin film and an unvulcanized rubber member are placed one on top of the other, and pressed from both sides with a mold at a temperature slightly lower than the melting point of the resin film, thereby vulcanizing the rubber member and bonding it to the resin film. However, when a diaphragm is molded by such a method, as shown in FIG. 2, the molding shrinkage of the resin film 1a is larger than that of the rubber member 1b, so that the resin film 1a warps as shown by the broken line. There is a problem that occurs.

The second problem is that warping also occurs when the diaphragm is used in a fuel pump or the like. FIG. 3 shows an example of a fuel pump, in which a diaphragm 1 is held between a body 2 and a cover 3 at its periphery, and is supported by a shaft 4 at a central center deck portion 11. The shaft 4 moves up and down in conjunction with, for example, a camshaft (not shown) of the engine, and gasoline fuel flows into the diaphragm chamber 5 through one valve (not shown) formed in the cover member 3 by the up and down movement of the diaphragm 1. and out through the other valve (not shown). In such a case, the resin film 1a may be a nylon film, vinylidene chloride film, polyvinylidene fluoride film,
Even if a film with excellent gasoline resistance, such as a polyester elastomer film, is used, some amount of gasoline will penetrate, and during long-term use, the rubber will swell due to the penetration of gasoline. In this case as well, a force is generated in the diaphragm that tends to warp it toward the resin film, and the outer portion of the center deck portion 11 is deformed.

When the diaphragm warps due to molding shrinkage, it becomes difficult to assemble the diaphragm when its outer periphery is sandwiched between the body 2 and the cover member 3 as shown in FIG. It is difficult to completely correct and assemble, resulting in reduced operational accuracy. It also becomes difficult to assemble the center deck.

On the other hand, if the rubber member 1b is deformed due to swelling after the diaphragm is assembled, the operating accuracy will decrease in the same way as described above, and peeling will occur between the rubber member 1b and the resin film 1a due to uneven elongation, and the diaphragm will Lifespan decreases.

The object of the present invention is to prevent the above warpage from occurring in a diaphragm formed by bonding a synthetic resin film and a rubber member.

Accordingly, the present invention achieves the above object by forming the surface of the diaphragm on the resin film side into an uneven shape.

Next, embodiments of the present invention will be described. As shown in FIG. 1, a diaphragm 1 is formed by joining a synthetic resin film 1a and a rubber member 1b. Diaphragm 1
The resin film side is formed into a corrugated uneven surface. The diaphragm 1 is obtained by the compression molding described above. However, in this case, the mold surface on the resin film side is made to have an uneven surface corresponding to the wave-like uneven surface of the intended diaphragm.

The height of the corrugation is preferably greater than the thickness of the resin film 1a and approximately 0.1 mm or more, and is approximately 1/4 of the total thickness of the diaphragm.
It is desirable that it be at or below that level.

However, in the diaphragm 1 in this embodiment, even if the molding shrinkage of the film itself is larger than that of the rubber 1b, since the surface area of the film 1a is large, the shrinkage of the film 1a that is larger than that of the rubber 1b is absorbed by the waveform, and This prevents the diaphragm from warping.

Furthermore, when the rubber 1b is swollen by gasoline that permeates the film 1a when used as a diaphragm of a fuel pump, the film 1a has a large surface area due to its corrugated shape, so the rubber 1b
By absorbing the deformation caused by the swelling of b, the occurrence of warp deformation is prevented.

4 and 5 respectively show other embodiments, the embodiment in FIG. 4 has trapezoidal irregularities formed on the synthetic resin film 1b, and the embodiment in FIG. 5 has triangular irregularities on the film 1b. It has an uneven shape and has the same effect as the embodiment shown in FIG.

As described above, the diaphragm of the present invention has a synthetic resin film and rubber bonded to each other, and the film side is molded to have an uneven surface, so that warping due to molding shrinkage can be prevented. Furthermore, when the diaphragm is used in a fuel pump, etc., it is possible to prevent the occurrence of warping due to swelling of the rubber, thereby improving assembly workability and accuracy, as well as prolonging the operability of the diaphragm. It can be maintained well over a period of time.

[Brief explanation of the drawing]

FIG. 1A is a sectional view of an embodiment of the diaphragm according to the present invention, FIG. 1B is an enlarged view of section C in FIG. 1A, and FIG.
The figure is a cross-sectional view of a conventional diaphragm and its warp deformation, FIG. 3 is a schematic diagram of a main part of a fuel pump using a diaphragm, and FIGS. 4 and 5 are cross-sections of main parts of other embodiments of the present invention. It is a diagram. 1...Diaphragm, 1a...Synthetic resin film, 1b...Rubber member.

Claims (1)

[Scope of utility model registration request] The diaphragm is made of a synthetic resin film and a rubber member, and the film and the rubber member are stacked and compression molded, the rubber member is vulcanized, and the rubber member and the film are bonded together.The diaphragm is made with an uneven surface on the film side. A diaphragm characterized by being molded into.