JP4711037B2 - Oil seal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil seal which is a kind of sealing device, and more particularly to a pressure-resistant oil seal having a structure for backing up a seal lip using a backup ring.
[0002]
[Prior art]
Conventionally, as shown in FIG. 6, a seal lip 53 that is slidably in contact with a peripheral surface 52 a of a mating member such as a shaft 52 is provided, and a backup ring 55 is held behind the seal lip 53 (upper and lower sides in the figure). There is known an oil seal 51 for pressure resistance or high pressure condition in which a backup ring holder portion 54 is provided and a backup ring 55 for backing up a seal lip 53 is provided on the backup ring holder portion 54.
[0003]
However, in this prior art, the inner diameter φA of the backup ring 55 is formed larger than the outer diameter φB of the shaft 52 as shown in the figure, so that a relatively large radial direction is provided between the backup ring 55 and the shaft 52. Since the gap c is formed, a part of the rubber of the oil seal 51 (a part on the back side of the seal lip 53 and a so-called heel part 53a) is sandwiched by the pressure gap in the radial gap c. The heel protrudes, and when the seal lip 53 slides with the shaft 52 in this state, the seal lip 53 may be peeled or swollen and the sealing performance may be hindered.
[0004]
In order to solve this problem, as shown in FIG. 7, the inner diameter φA of the backup ring 55 is reduced and formed so as to be substantially the same as the outer diameter φB of the shaft 52. It is conceivable to prevent the radial gap c from being formed between them.
[0005]
However, in this case, as shown in FIG. 8, when the backup ring 55 is pushed and spread by the shaft 52 when the shaft 52 is inserted, there is no escape space on the outer peripheral side of the backup ring 55. As a result, there is an inconvenience that the assembling workability is not so good with respect to the insertion of the shaft 52, and the backup ring 55 is pushed in the radial direction by the eccentricity of the shaft 52 after the shaft 52 is inserted, as shown in FIG. Then, a relatively large load acts on the rubber-to-metal bonding portion 56 in the oil seal 51, which may cause peeling of the adhesive.
[0006]
[Problems to be solved by the invention]
In view of the above, the present invention can improve the assembly workability of a shaft and the like in an oil seal having a structure for backing up a seal lip using a backup ring. It is an object of the present invention to provide an oil seal capable of suppressing the occurrence of peeling of adhesion when there are adhesive portions.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the oil seal of the present invention has a seal lip that is slidably in close contact with a peripheral surface of a mating member such as a shaft, and a backup ring holder portion is provided behind the seal lip, and the backup In the oil seal in which the backup ring is arranged in the ring holder part, the backup ring is provided with a bias cut obtained by obliquely cutting one place on the circumference, and the inner surface of the backup ring holder part and the backup ring An annular gap is formed between the elastic ring, an elastic protrusion is provided on the inner surface of the backup ring holder portion toward the backup ring, the elastic protrusion is formed in an annular shape, and the annular elastic protrusion is formed on the backup ring. Is pressed against a mating member such as the shaft .
[0010]
In the oil seal of the present invention having the above-described configuration, an annular gap is formed between the inner surface of the backup ring holder portion and the backup ring, and an annular elastic protrusion is formed on the backup ring holder portion toward the backup ring. Therefore, even if the backup ring is pushed and expanded by the shaft or the like when the shaft or the like is inserted, the backup ring can secure the escape area by crushing the elastic protrusion. Further, after the shaft or the like is inserted, even if the backup ring is pushed in the radial direction due to the eccentricity of the shaft or the like, the load can be absorbed by the backup ring crushing the elastic protrusion. In addition, in the oil seal of the present invention , since the backup ring is pressed against the shaft or the like by the elastic protrusion provided on the backup ring holder portion, a radial gap is formed between the backup ring and the shaft or the like. Therefore, it is possible to effectively suppress the occurrence of the above-described heel protrusion.
[0011]
The proposal includes the following technical matters.
[0012]
That is, in order to achieve the above object, one oil seal proposed in the present application is provided with a protrusion on the backup ring holder portion, and the backup ring is always pressed against the shaft to minimize the gap between the shaft and the backup ring. This suppresses the phenomenon of rubber entering the gap between the backup ring and the shaft. Moreover, the backup ring can spread outward by using a protrusion as a mechanism for pressing the backup ring against the shaft. Therefore, the ease of assembly of the seal can be maintained by this, and the adverse effects due to the shaft eccentricity can be avoided.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 shows a cross section (cut end face) of an oil seal 1 according to an embodiment of the present invention.
[0015]
The oil seal 1 according to this embodiment is a pressure-resistant or high-pressure oil seal having a structure for backing up a seal lip 6 as a constituent element with a backup ring 8 and is configured as follows. .
[0016]
That is, first, an oil seal body 2 is provided by vulcanizing and bonding a rubber 4 to a metal mounting ring 3, and the oil seal body 2 is slidably in close contact with the peripheral surface 5 a of the shaft 5. A seal lip 6 that seals between the oil seal 1 and the shaft 5, a backup holder portion 7 that holds the backup ring 8, and a housing (not shown) in which the oil seal 1 and the oil seal 1 are mounted. A peripheral seal portion 9 that seals the gap is integrally formed. A garter spring 10 for adjusting contact pressure is fitted to the seal lip 6.
[0017]
The backup ring holder portion 7 provided on the axially rear side (upper and lower sides in the figure) of the seal lip 6 is formed in an annular groove shape opened radially inward by the rubber 4 and the mounting ring 3 described above. A backup ring 8 for backing up the seal lip 6 is fitted to the groove-shaped holder portion 7. An elastic protrusion 11 is integrally formed on the inner surface of the holder portion 7 inward in the radial direction. A backup ring 8 is disposed on the inner peripheral side of the elastic protrusion 11. Due to the elasticity, the backup ring 8 is slidably pressed against the peripheral surface 5 a of the shaft 5. An annular gap 12 is formed between the inner surface of the holder portion 7 and the backup ring 8.
[0018]
As shown in FIG. 2, a plurality of protrusions 11 are formed in a uniform manner with a predetermined interval on the circumference, but may be formed in an annular shape. The cross-sectional shape of the protrusion 11 is not particularly limited.
[0019]
Further, the backup ring 8 is formed of a material such as a resin having a hardness higher than that of the rubber 4 of the oil seal body 2, and the inner diameter dimension φA in the initial state is formed to be substantially the same as the outer diameter dimension φB of the shaft 5. Has been. Further, as shown in FIG. 3, the backup ring 8 is provided with a bias cut 8a obtained by obliquely cutting one place on the circumference, so that the initial state of FIG. It is possible to enlarge the diameter dimension by deformation as shown in FIG. 3), and to reduce the diameter dimension by deformation as shown in FIG. 3C from the initial state of FIG. It is possible.
[0020]
In the oil seal 1 configured as described above, the elastic protrusion 11 is provided radially inward on the inner surface of the backup ring holder portion 7 in the oil seal main body 2, and the backup ring 8 is disposed on the inner diameter side of the elastic protrusion 11. Therefore, as shown in FIG. 4, when the backup ring 8 is pushed and spread by the shaft 5 when the shaft 5 is inserted, the backup ring 8 escapes radially outward by temporarily crushing the elastic protrusion 11. Is possible. Therefore, since the escape place of the backup ring 8 when the shaft 5 is inserted is ensured in this way, the assembling workability when the shaft 5 is inserted can be improved.
[0021]
Further, as shown in FIG. 5, after the shaft 5 is inserted, when the backup ring 8 is pushed in the radial direction due to the eccentricity of the shaft 5, the backup ring 8 temporarily crushes the elastic protrusion 11, thereby causing the eccentricity of the shaft 5. It is possible to absorb the load. Therefore, by absorbing the load in this way, it is possible to suppress the load from acting on the bonding portion 13 between the rubber 4 and the mounting ring 3 in the oil seal main body 2, and thus, peeling of the adhesive can be prevented. Can be suppressed.
[0022]
In addition, since the backup ring 8 is pressed against the peripheral surface 5a of the shaft 5 by the elastic protrusion 11, according to this configuration, a radial gap is formed between the backup ring 8 and the shaft 5 as in the prior art. There is nothing. Accordingly, it is possible to suppress the occurrence of heel protrusion in which the heel portion 6a of the seal lip 6 is sandwiched between the radial gaps, and thereby it is possible to prevent the seal lip 6 from being peeled or swollen.
[0023]
In addition, when the backup ring 8 is cut as described above, the elastic protrusion 11 is provided so that the adhesiveness of the cut portion is kept good and the eccentric followability and the adhesiveness to the shaft 5 are improved. be able to.
[0024]
The effect of preventing the heel from protruding is not only when the backup ring 8 is pressed against the peripheral surface 5a of the shaft 5 by the elastic protrusion 11, but also when the elastic protrusion 11 functions as a kind of spacer. This can be achieved to some extent even when the contact pressure with respect to is set to zero. Therefore, in a state where the shaft 5 is not yet eccentric, the backup ring 8 may be configured not to be pressed against the shaft 5 by the elastic protrusion 11 but to be in contact with the shaft 5 with just a contact pressure of zero.
[0025]
【The invention's effect】
The present invention has the following effects.
[0028]
That is, in the oil seal of the present invention having the above-described configuration, an annular space is formed between the inner surface of the backup ring holder portion and the backup ring, and then the elastic elasticity of the annular shape toward the backup ring is formed in the backup ring holder portion. Since the protrusion is provided, when the backup ring is pushed and expanded by the shaft or the like during insertion of the shaft or the like, the backup ring can escape in the radial direction by squeezing the elastic protrusion. Therefore, since the backup ring can escape when the shaft or the like is inserted in this way, the assembling workability when the shaft or the like is inserted can be improved.
[0029]
When the backup ring is pushed in the radial direction due to the eccentricity of the shaft or the like after the shaft or the like is inserted, the backup ring can absorb the load due to the eccentricity of the shaft or the like by crushing the elastic protrusion. Therefore, since it is possible to absorb the load in this way, when the oil seal has an adhesive portion between rubber and metal, it is possible to suppress the load from acting on the adhesive portion, and thus the adhesion peeling does not occur. Occurrence can be suppressed.
[0030]
In addition, since the backup ring is pressed against the peripheral surface of the shaft or the like by the elastic protrusion provided on the backup ring holder portion, a radial gap is formed between the backup ring and the shaft or the like as in the above-described prior art. There is no. Therefore, it is possible to suppress the occurrence of heel protrusion in which the heel portion of the seal lip is sandwiched between the radial gaps, and thereby it is possible to prevent the seal lip from being peeled or swept away.
[Brief description of the drawings]
FIG. 1 is a half cut end view of an oil seal according to an embodiment of the present invention. FIG. 2 is a partial sectional view of an oil seal body in the oil seal. FIG. 3A is an initial view of a backup ring in the oil seal. FIG. 4B is a partial cross-sectional view showing a state in which the backup ring is enlarged in diameter, and FIG. 4C is a partial cross-sectional view showing the state in which the backup ring is reduced in diameter. Half-cut end view showing the state of the oil seal when the shaft is inserted [FIG. 5] Half-cut end view showing the state of the oil seal when the shaft is eccentric [FIG. 6] Half-cut end view of the oil seal according to the prior art 7] Half cut end view of the oil seal according to the comparative example. [FIG. 8] Half cut end view showing the state of the oil seal when the shaft is inserted. [FIG. 9] Half cut end face showing the state of the oil seal when the shaft is eccentric. Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Oil seal 2 Oil seal main body 3 Mounting ring 4 Rubber 5 Shaft 5a Circumferential surface 6 Seal lip 6a Heel part 7 Backup ring holder part 8 Backup ring 8a Bias cut 9 Outer seal part 10 Garter spring 11 Elastic protrusion 12 Gap 13 Adhesive part

Claims (1)

A seal lip (6) slidably in contact with a peripheral surface (5a) of a mating member such as a shaft (5), and a backup ring holder portion (7) provided behind the seal lip (6); In the oil seal (1) in which the backup ring (8) is arranged in the backup ring holder part (7),
The backup ring (8) is provided with a bias cut (8a) obtained by obliquely cutting one place on its circumference.
An annular gap (12) is formed between the inner surface of the backup ring holder part (7) and the backup ring (8),
An elastic protrusion (11) is provided on the inner surface of the backup ring holder part (7) toward the backup ring (8) ,
The oil seal characterized in that the elastic protrusion (11) is formed in an annular shape, and the annular elastic protrusion (11) presses the backup ring (8) against a mating member such as the shaft (5) .

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