JP2598568Y2 - Oil seal for pressure-resistant reciprocating motion - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-resistant reciprocating oil seal mounted on a shaft for preventing oil leakage of a reciprocating device in an automobile or various industrial machines.

[0002]

2. Description of the Related Art Conventionally, as an example of an oil seal used in this type of device, abnormal noise is generated due to friction between a reciprocating shaft and a lip portion of the oil seal in contact with the shaft during high pressure operation. In order to prevent this, a circumferential groove having a constant depth is provided at a small pitch on the inner peripheral surface of the lip portion on the outer side in the axial direction. The peripheral groove reduces the contact area between the lip and the shaft, reduces the sliding resistance, suppresses sound generation, and has an effect of promoting lubrication because an oil film is held between the peripheral grooves.

[0003]

However, in such an oil seal, since the circumferential groove is uniformly provided from the tip of the lip to the waist where the lip ends,
There was a problem that the strength of the waist was weak. This is because when the pressure inside the seal increases and the lip is pressed against the shaft, and the peripheral groove is pressed against the shaft, the waist is extended with the distance to the shaft and the waist deforms due to the arc shape The reason for this is that if the waist has a circumferential groove, a crack is formed in the valley and the waist is broken.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide an oil seal having a lip portion having a circumferential groove and an increased waist strength.

[0005]

According to the present invention, in order to achieve the above object, a circumferential groove is formed on an inner peripheral surface of a lip portion to be fitted to a shaft, except for a waist portion at a position where the lip portion ends. And the depth of the peripheral groove in the portion close to the waist is made smaller than the depth of the peripheral groove in the other portion.

According to the present invention, a circumferential groove is provided on an axially outer inner peripheral surface of a lip portion to be fitted to a shaft except for a waist portion at a position where the lip portion ends, and a depth of the circumferential groove is set to a lip. It is characterized in that it is gradually reduced from the tip of the part to the waist.

[0007]

Therefore, according to the present invention, by providing the peripheral groove in a range excluding the waist at the position where the lip portion ends,
The strength of the waist is increased, and no crack is generated in the waist when the lip is pressed against the shaft.

Further, according to the present invention, the depth of the peripheral groove in the portion close to the waist is made smaller than the depth of the peripheral groove in the other portion, or the depth of the peripheral groove is increased from the tip of the lip to the waist. By gradually reducing the size, even if the waist is greatly deformed when the lip is pressed against the shaft, the strength near the waist is high and the stress can be dispersed.

[0009]

FIG. 1 shows one embodiment of the present invention.
The oil seal is obtained by integrally molding a seal portion 2 made of an elastic material such as rubber or synthetic resin on a metal reinforcing ring 1 having an L-shaped cross section. A lip portion 3 is provided on the inner peripheral end of the seal portion 2.
Are formed, and a circumferential groove 4 is formed on the inner peripheral surface in the axial direction. The peripheral groove 4 is formed by forming an independent annular groove by turning on a corresponding surface of an oil seal molding die. The curved surface portion at the end of the inner peripheral surface in the axial direction of the lip portion 3 is a waist portion 5, and the circumferential groove 4 is not formed in the waist portion 5. The outer periphery of the oil seal is press-fitted into the housing 6 of the machine, the shaft 7 is inserted into the lip portion 3 of the inner periphery, and is pressed against the shaft 7 by a spring 8. In the figure, the left side is inside the machine, and the right side is outside the machine, which prevents oil inside the machine from leaking to the outside of the machine along the reciprocating shaft 7.

FIG. 2 is an enlarged view of the inner peripheral surface of the lip portion 3 of the oil seal in the axial direction. Since the continuous circumferential groove 4 has a mountain between adjacent circumferential grooves,
If you change the viewpoint, you can see it as a protrusion, and in this embodiment,
The protrusion formed by the circumferential groove formed in the molding die is referred to as a circumferential groove 4. The range W from the lip tip where the peripheral groove 4 is provided is 1.9 mm, and the waist portion 5 is formed into a curved surface having a radius R of 0.5 mm. The range up to the line S perpendicular to the tangent line T of the waist portion 5 is the waist portion, and the line S is the limit of the range W where the circumferential groove 4 is provided. In the present embodiment, the circumferential groove 4 is provided after being spaced from the line S by the pitch P of the circumferential groove 4. The pitch P of each circumferential groove 4 is 0.1 mm, and the pitch P provided in the range W1 on the waist 5 side is
The depth D1 of each of the peripheral grooves 4 is 0.01 mm, and the depth D2 of the peripheral groove 4 provided in the range W2 on the tip side of the remaining lip is 0.03 mm.
It is.

Next, a test for verifying the effect of the present invention will be described. First, the test results regarding the depth of the circumferential groove 4 are shown in FIG. In this test, in the above example, the depth of the circumferential groove 4 was made uniform over the entire range W, and was 0.1, 0.05, 0.04, 0.03, 0.02,
It shows the results of five tests on six types of 0.01 mm samples. As is apparent from this figure, when the depth of the peripheral groove 4 is made uniform, the depth is 0.01 mm or more,
Up to less than 3 mm, it is possible to obtain a good depth where cracks do not occur near the waist portion 5. If the depth of the circumferential groove 4 is smaller than 0.01 mm, the sliding resistance increases, which is not preferable.

Next, FIG. 4 shows test results when the depth of the circumferential groove 4 is not made uniform and the portion close to the waist portion 5 is made smaller than the other portions as in the above embodiment. Here, types A, B, D, and E are obtained by changing D1 and D2 in the above embodiment, respectively, and type C is 4 in the range W1.
Of the peripheral grooves, the depth of two of the waist portions 5 was 0.01 mm, the depth of the remaining two was 0.02 mm, and the depth in the range W2 was 0.03 mm. The test conditions are the same as the above test.

As is apparent from FIG. 4, good results were obtained in which cracks did not occur near the waist 5 except for the type A sample in which the depth D1 of the circumferential groove 4 on the waist 5 side was 0.03 mm. Was. However, type E in which the depth D2 on the lip tip side is 0.02 mm is not preferable because abnormal noise is generated due to an increase in sliding resistance. So, in conclusion,
The depth D1 on the waist 5 side is 0.01 mm or more and less than 0.03 mm, and the depth D2 on the lip tip side is 0.03 mm to 0.1 mm.
It is better to be in the range of mm.

[0014]

As described above, according to the present invention, by providing the circumferential groove in a range excluding the waist at the position where the lip ends, the waist is greatly deformed when the lip is pressed against the shaft. Even so, the strength of the waist is high and cracks do not occur.

Further, according to the present invention, the depth of the peripheral groove in the portion close to the waist is made smaller than the depth of the peripheral groove in the other portion, or the depth of the peripheral groove is increased from the tip of the lip to the waist. By making the lip portion smaller gradually, even when the lumbar portion is greatly deformed when the lip portion is pressed against the shaft, the strength near the lumbar portion is high and the stress can be dispersed.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an oil seal showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a peripheral groove portion in the embodiment.

FIG. 3 is a list showing test results for confirming effects in the example.

FIG. 4 is a list showing another test result for confirming the effect in the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal reinforcement ring 2 Seal part 3 Lip part 4 Peripheral groove 5 Waist part 6 Housing 7 Shaft 8 Spring

Claims (2)

(57) [Scope of request for utility model registration] 1. An oil seal in which a circumferential groove is provided at a small pitch on an axially outer inner circumferential surface of a lip portion fitted to a shaft, wherein the circumferential groove is formed in a range excluding a waist portion at a position where the lip portion ends. A pressure-resistant reciprocating oil seal, wherein the depth of a peripheral groove in a portion close to the waist portion is smaller than the depth of a peripheral groove in another portion. 2. In an oil seal in which circumferential grooves are provided at a small pitch on an axially outer inner circumferential surface of a lip portion fitted to a shaft, the circumferential groove is formed in a range excluding a waist portion at a position where the lip portion ends. The pressure seal reciprocating oil seal, wherein the depth of the peripheral groove is gradually reduced from the tip of the lip to the waist.