JP2590028Y2 - Peripheral rubber mating type oil seal - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil seal having an outer peripheral surface fitted into a housing. More specifically, the present invention relates to an outer peripheral rubber-fitted oil seal that has been subjected to a surface treatment for preventing it from coming off.

[0002]

2. Description of the Related Art An oil seal generally called an outer peripheral rubber fitting type is an oil seal which is used by covering an outer peripheral portion of a metal ring with a rubber material and fitting an outer peripheral portion of the rubber material to a housing. An outer peripheral rubber oil seal with a spring and a spring and an outer peripheral rubber oil seal with a spring as shown in FIG. 2 are examples. In the case of the illustrated outer peripheral rubber oil seal, a dust lip 3 and a sealing lip 4 are formed by a rubber material 2 covering the metal ring 1, and a garter spring 5 is mounted. Then, a fitting force (force required for disengagement) is developed by press-fitting a space (housing hole) 7 inside the housing 6 for holding the seal with a required fitting margin so that the housing 6 does not come off. In addition, the sealing performance of the fitting surface and the outer peripheral rubber surface 8 with the housing 6 is ensured. Therefore, it is necessary to obtain a certain fitting force with respect to the housing 6.

Conventionally, as a method of increasing the fitting force in such an outer peripheral rubber fitting type oil seal, for example, a method of changing the outer diameter of the oil seal to increase the interference with the housing or a rubber material having a high Young's modulus is used. It is common to use materials and the like.

[0004]

However, in the case of a conventional oil seal of the outer peripheral rubber fitting type, when the oil seal is heated to 80 ° C. to 150 ° C. after being fitted to the housing, the friction coefficient becomes small and the fitting force is reduced. This can sometimes cause a significant drop, eventually causing the oil seal to fall out of the housing. Further, even when the housing is at room temperature, if oil, grease, or the like adheres to the housing fitting surface, there is a danger that a problem that the oil seal comes off the housing may occur.

The inventors of the present invention have conducted various studies on this fact. As a result, it has been found that wax and the like in the rubber composition precipitate on the outer peripheral rubber surface fitted with the housing (blooming).
However, it has been found that when the ambient temperature is heated to 80 ° C. to 150 ° C., it melts and changes into a liquid to lower the friction coefficient. Further, when the oil seal is press-fitted into the housing, the rubber 2 partially protrudes outside the housing 6 or on the edge of the hole as indicated by reference numeral 9 and continuously.
The force is applied in the direction that comes out. For this reason, when the fitting temperature (extraction force) is reduced due to a decrease in the friction coefficient due to a rise in the use atmosphere temperature, or when grease or the like adheres to the housing fitting surface, the restoring force of the elastically deformed rubber is reduced. The oil seal comes off due to the force in the pull-out direction.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an outer rubber-fitted oil seal which does not come off even if the temperature of the operating environment rises or grease adheres to the housing fitting surface.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the outer peripheral rubber fitting type oil seal of the present invention has a melting point of 1 point.
A powder having a temperature of 60 ° C. or higher is dispersed in a liquid base material and applied to the outer peripheral surface of the oil seal. Where the powder is
It is required to have a strength that is not easily broken by a force sandwiched between the rubber and the housing, and a chemical stability that is not easily deteriorated or deteriorated by oil or grease attached to the outer peripheral rubber surface. Therefore, inorganic powders are desirable as the powder, and for example, talc, magnesia, silica, clay and the like can be used, and one or a combination of two or more of them may be used.

[0008] The powder must have a melting point of 160 ° C or higher. The reason why the temperature is set to 160 ° C. or higher is to prevent the liquid from changing from a solid to a liquid up to a heating upper limit of 150 ° C. which is considered in a general use environment of an oil seal.

The powder has an average particle size of 0.01.
It is preferable that the thickness be more than μm and less than 10 μm. When the particle size of the powder is 0.01 μm or less, the thickness becomes equal to or less than the thickness of the liquid film interposed on the rubber surface, and the fitting force by the powder cannot be exhibited. If the thickness is 10 μm or more, there is a risk that the lip may be broken when the powder bites into the lip of the oil seal.

On the other hand, the liquid base material is desirably a material capable of uniformly dispersing the inorganic powder as a coating agent containing the powder. In addition, it is desirable that the liquid base material be dried after being applied to the oil seal in order to improve workability. This drying is preferably performed at room temperature for a relatively short time, for example, at most about 3 days to complete the coating. As such a liquid base material, for example, a drying oil which has volatility and is often used as a rust inhibitor can be used.

The amount of the powder mixed with the liquid substrate is preferably from 40% by weight to 80% by weight based on the liquid substrate. If the amount of the powder mixed with the liquid base material is less than 40% by weight, the amount of the powder is small, so that a sufficient fitting force by the powder cannot be obtained. Is not obtained, and the coating operation becomes extremely poor.

[0012]

Therefore, as shown in FIG. 1, the powder 11 contained in the liquid base material 10 is finely dispersed on the outer peripheral surface of the rubber 2, and when the oil seal is mounted on the housing 6, the powder 11 is 2 and the housing 6. When the working atmosphere of the oil seal is heated to 80 ° C. to 150 ° C., even if wax or the like deposited on the surface of the rubber 2 is melted and a liquid film 12 is formed on the surface of the rubber 2, only the powder 11 It protrudes from the membrane 12 and is in contact with the housing 6 to increase the frictional force between the outer peripheral rubber surface and the fitting surface. Further, even at normal temperature, even if grease or the like adheres to the housing fitting surface, the powder 11 and the housing 6 come into contact with each other and increase the frictional force.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on embodiments.

[Example 1] Talc (manufactured by Nippon Talc Co., Ltd., trade name: Micro Ace L-2) as a powder, and rust preventive oil (manufactured by Nippon Grease Co., Ltd., trade name: Las Fighter) as a liquid base material. Using,
20% by weight of talc was added to the rust preventive oil. The rust-preventive oil containing this talc was applied to the outer peripheral surface of an acrylic rubber outer peripheral rubber fitting type oil seal, and dried at room temperature.

Example 2 The same talc and rust-preventive oil as in Example 1 were used as the powder and the liquid base material, but in this example, 40% by weight of talc was mixed with the rust-preventive oil. Others are the same as the first embodiment.

Example 3 Rust-preventing oil was mixed with 60% by weight of talc. Others are Example 1.
Is the same as

Example 4 80% by weight of talc was mixed with rust preventive oil. Others are Example 1.
Is the same as

[Comparative Example Conventional Product] An outer rubber-fitting oil seal made of acrylic rubber which is not coated with a liquid base material containing inorganic powder as in the present invention.

The outer peripheral rubber-fitting oil seals of Examples 1 to 4 and Comparative Example obtained as described above were pressed into the housing at room temperature, and the oil seals came out of the housing at 120 ° C. in an atmosphere. The required load (fitting force) was measured. Table 1 shows the experimental results.

[0020]

Table 1 Example 1 Example 2 Example 3 Example 4 Comparative Example Inorganic powder amount (wt /%) 20 40 60 80 0 Extraction load (kgf) 5 15 20 20 0 Judgment Somewhat poor Good Good Good Bad

As a result of this experiment, an oil seal (comparative example) in which a liquid base material containing an inorganic powder was not applied was directly melted and liquefied at 120 ° C. under an ambient temperature of 120 ° C. Because it came into contact with the housing, the coefficient of friction was reduced and it slipped out easily. On the other hand, Examples 3 and 4, in which the liquid base material containing the inorganic powder was applied to the surface of the oil seal, required a pull-out load of 20 kgf and could be evaluated as having a sufficient fitting force. Example 2 is 15 kg
Although it came out of the housing with a pulling load of f, it could be evaluated that this also had a sufficient fitting force. Example 1 is 5 kg
When the talc was added to the rust preventive oil at a relatively small amount of 20% by weight, the frictional force was not effectively increased, and a sufficient mating force could not be obtained. I understand.

[0022]

As is apparent from the above description, the outer peripheral rubber-fitting type oil seal of the present invention disperses powder having a melting point of 160 ° or more in a liquid base material and applies it to the outer peripheral surface of the oil seal. Therefore, even if the powder is interposed between the rubber and the housing, and wax or the like deposited on the rubber surface is melted by the use atmosphere of the outer peripheral oil seal to form a liquid film, the housing mating surface can be formed at room temperature. Even if grease or the like adheres, only the powder protrudes from the liquid film and comes into contact with the housing to maintain the frictional force between the outer peripheral rubber surface and the fitting surface. Therefore, the oil seal does not come off from the housing even when the operating environment temperature rises. In particular, when the average particle diameter of the powder is more than 0.01 μm and less than 10 μm, the lip is not broken, and the maintenance of the fitting force by the powder can be ensured. Further, when the amount of dispersion of the powder liquid in the liquid base material is 40% by weight or more and 80% by weight or less, the powder can be evenly and uniformly applied to the rubber surface and the coating operation is easy.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a fitting part of a peripheral rubber fitting type oil seal of the present invention with a housing.

FIG. 2 is a cross-sectional view showing an example of an outer rubber-fitted oil seal.

[Explanation of symbols]

 2 Rubber 6 Housing 10 Liquid base material 11 Powder 12 Liquid film

Claims (3)

(57) [Scope of request for utility model registration] 1. An outer rubber-fitted oil seal characterized in that powder having a melting point of 160 ° C. or higher is dispersed in a liquid base material and applied to the outer peripheral surface of the oil seal. 2. The powder according to claim 1, wherein the powder has an average particle diameter of more than 0.01 μm and less than 10 μm.
The outer peripheral rubber fitting type oil seal described in the above. 3. The oil seal according to claim 1, wherein the powder is contained in an amount of 40% by weight or more and 80% by weight or less with respect to the liquid base material.