JP2009180252A - Shaft seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft seal superior in following performance to shaft eccentricity and dust resistance. <P>SOLUTION: This shaft seal has an annular dust lip 40 for restraining infiltration of dust from an external part in a state of slide contact with an outer peripheral surface 10a of a shaft 10. The duct lip 40 obliquely projects to the external side toward the inside in the radial direction of the shaft 10, and has a constitution of thinning toward the tip, and has a projection part 41 extended in parallel in the axial direction Z of the shaft 10 on an inner peripheral surface 40a of the dust lip 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shaft seal provided with an annular dust strip that suppresses intrusion of dust from the outside while being in sliding contact with the outer peripheral surface of the shaft, and more particularly to a shaft seal for a shock absorber.

  Gas-filled shock absorbers that absorb vertical vibrations of a vehicle are filled with highly viscous oil and gas for absorbing vibrations. The shaft seal that seals oil and gas includes a main lip that suppresses leakage of oil from the inside and a dust lip that suppresses entry of dust from the outside. However, if a gas sealing jig is inserted between the dust lip and the shaft from the outside during gas sealing, the sliding surface of the rubber dust lip may be damaged and the sealing performance may be impaired.

  Therefore, as a shaft seal capable of preventing damage to the sliding surface of the dust lip due to insertion of the gas sealing jig, a shaft seal having a protrusion 4 on the dust lip 3 is known as shown in FIG. (For example, refer to Patent Document 1). The dust lip 3 includes an outer dust lip 3a and a second-stage dust lip 3b, and a groove 3d is formed in the second-stage dust lip 3b.

By pressing the protrusion 4 in the direction of arrow A by the pressing member 5, the outer dust lip 3a is separated from the sliding surface of the shaft 201 with the second dust lip 3b as a fulcrum. The gas can be sealed in the direction of the arrow A1 by using. Therefore, it is possible to prevent damage to the sliding surface of the dust lip 3 due to insertion of the gas sealing jig.
JP-A-9-126324

  However, since the second-stage dust lip 3b having the above-described conventional configuration extends along the circumferential direction of the shaft 201, it is not intended to increase the axial rigidity of the outer dust lip 3a.

  Further, in recent years, in order to improve the followability with respect to the shaft eccentricity and the dust resistance, instead of the block-shaped round type dust lip 3 as shown in FIG. 3, the thickness becomes thinner toward the tip as shown in FIG. A scraper-type dust strip formed in this way is used.

  FIG. 4 is a cross-sectional view schematically showing a problem of a shaft seal provided with a conventional scraper type dust lip. The scraper type dust lip 6 has lower axial rigidity than the round type dust lip 3. For this reason, when the shaft 7 moves inward (in the direction of arrow B) along the axial direction, the tip of the dust lip 6 is dragged inwardly by the shaft 7 as shown in FIG. There is. Then, for example, as shown in FIG. 4B, when the moving direction of the shaft 7 is reversed from the inner side (arrow B direction) to the outer side (arrow C direction), the elastic deformation of the dust lip 6 is used as a basis. The restoring force to be returned is released, and the dust lip 6 may be separated from the outer peripheral surface of the shaft 7. As a result, entry of dust from the outside is allowed.

  This invention is made | formed in view of the above, Comprising: It aims at providing the shaft seal excellent in the followable | trackability with respect to shaft eccentricity, and dust resistance.

In order to achieve the above object, the first invention provides a shaft seal including an annular dust strip that suppresses intrusion of dust from the outside while being in sliding contact with the outer peripheral surface of the shaft.
The dust lip protrudes obliquely toward the outside toward the inside in the radial direction of the shaft, and has a configuration that becomes thinner toward the tip.
A convex portion is provided on the inner peripheral surface of the dust lip so as to extend parallel to the axial direction of the shaft.

  2nd invention is a shaft seal which concerns on 1st invention, Comprising: The said convex part is installed with two or more at equal intervals along the circumferential direction of the said axis | shaft.

  3rd invention is a shaft seal which concerns on 1st or 2nd invention, Comprising: The said dust strip is a ring shape whose elastic modulus is higher than the said dust strip on the sliding surface which slidably contacts with the said outer peripheral surface of the said shaft. A member is further provided.

4th invention is a shaft seal provided with the annular dust lip which suppresses invasion of dust from the outside in the state of sliding contact with the outer peripheral surface of the shaft,
The dust lip protrudes obliquely toward the outside toward the inside in the radial direction of the shaft, and has a configuration that becomes thinner toward the tip.
The dust lip includes a ring-shaped member having a higher elastic modulus than the dust lip on a sliding surface that is in sliding contact with the outer peripheral surface of the shaft.

  According to 1st-3rd invention, the rigidity of the axial direction of a dust lip can be improved by providing the convex part extended in parallel with respect to the axial direction of an axis | shaft on the internal peripheral surface of a dust lip. . Therefore, it is possible to prevent the tip of the dust lip from being dragged inward by the shaft. As a result, the dust lip is separated from the outer peripheral surface of the shaft by a restoring force that attempts to restore the elastic deformation of the dust lip. Can be suppressed. As a result, entry of dust from the outside can be suppressed. Since this convex portion is not installed on the entire inner peripheral surface of the dust lip, the flexibility of the dust lip is less likely to be lost, and the followability to the shaft eccentricity is less likely to be impaired.

  According to the fourth invention, the elastic modulus of the sliding surface of the dust lip can be improved by providing the ring-shaped member having a higher elastic modulus than that of the dust lip on the sliding surface where the dust lip is in sliding contact with the outer peripheral surface of the shaft. it can. Therefore, elastic deformation of the sliding surface of the dust lip can be suppressed, and separation of the sliding surface of the dust lip from the outer peripheral surface of the shaft can be suppressed. As a result, entry of dust from the outside can be suppressed. Since this ring-shaped member is installed on the free end (tip) side of the dust lip, the flexibility of the dust lip is less likely to be lost, and the followability to the shaft eccentricity is less likely to be impaired.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a partial cross-sectional view showing an example of the configuration of the shaft seal of the present invention. The shaft seal is provided for sealing a gap between a shaft 10 provided coaxially and relatively reciprocatingly moving and a housing (not shown). For example, the shaft seal includes a rubber seal portion 20 and a metal reinforcing ring 51. The seal portion 20 has an annular shape, and the inner peripheral surface is in sliding contact with the outer peripheral surface 10 a of the shaft 10, and the outer peripheral surface is fitted by a metal reinforcing ring 51. The seal portion 20 is connected to the housing via a metal reinforcing ring 51.

  The seal portion 20 includes a main lip 30 that suppresses leakage of oil from the inside and a dust lip 40 that suppresses intrusion of dust from the outside while being in sliding contact with the outer peripheral surface 10 a of the shaft 10. The main lip 30 and the dust lip 40 are integrally formed of rubber such as nitrile rubber (NBR) or fluorine rubber (FKM), and are installed coaxially with the shaft 10.

  The main lip 30 scrapes back the oil adhering to the outer peripheral surface 10a of the shaft 10 to the inside and returns it to a reservoir chamber (not shown) installed in the housing. A main lip portion 31 and a sub lip portion 32 project from the inner peripheral surface of the main lip 30 in order to suppress oil leakage from the inside.

  The main lip portion 31 and the sub lip portion 32 are annular members having a substantially triangular shape in a sectional view and apex toward the outer peripheral surface 10 a of the shaft 10, and the inner diameter dimension of each apex is slightly smaller than the outer dimension of the shaft 10. And is slidably contacted with the outer peripheral surface 10a of the shaft 10 in a liquid-tight manner.

  The main lip portion 31 may be dragged and deformed by the shaft 10 along with the relative reciprocation of the shaft 10 and the housing. When this deformation is repeated, the sealing performance of the main lip portion 31 is impaired. Therefore, in order to suppress deformation of the main lip portion 31, the sub lip portion 32 is installed on the outer side from the main lip portion 31. The inner diameter of the top end of the sub lip portion 32 is slightly larger than the inner diameter of the top end of the main lip portion 31.

  A spring ring 52 is mounted on the outer peripheral surface 30 a of the main lip 30 at a position corresponding to the main lip portion 31. The spring ring 52 urges the top end of the main lip portion 31 to the outer peripheral surface 10 a of the shaft 10 by a pressing force inward in the radial direction. Thereby, the adhesiveness of the main lip 30 and the axis | shaft 10 can be improved, the liquid-tightness of a shaft seal can be improved, and the oil leak from an inside can be suppressed.

  The dust lip 40 is disposed outside the main lip 30. The front end edge 40b of the dust lip 40 is formed so that its inner diameter dimension is slightly smaller than the outer dimension of the shaft 10, and is slidably elastically contacted with the outer peripheral surface 10a of the shaft 10. Therefore, the dust adhering to the outer peripheral surface 10a of the shaft 10 can be scraped out to the outside by the tip edge 40b of the dust lip 40.

  Further, the dust lip 40 has a configuration that projects obliquely outward toward the inside in the radial direction of the shaft 10 and becomes thinner toward the tip. That is, the dust lip 40 has a configuration that becomes thinner toward the outside along the axial direction Z of the shaft 10 and approaches the outer peripheral surface 10 a of the shaft 10. That is, the dust lip 40 is of a so-called scraper type. Therefore, the tip edge 40b of the dust lip 40 follows the axial eccentricity between the shaft 10 and the housing by bending in a direction perpendicular to the axis with the portion where the dust lip 40 is fixed by the metal reinforcing ring 51 as a fixed end. can do.

  As shown in FIG. 1, the dust lip 40 includes a convex portion 41 extending in parallel with the axial direction Z of the shaft 10 on the inner peripheral surface 40 a as shown in FIG. 1. The convex portion 41 has a triangular shape in which a cross-sectional shape perpendicular to the axial direction of the shaft 10 forms a vertex toward the outer peripheral surface 10 a of the shaft 10. The top end of the convex portion 41 has an inner diameter dimension substantially the same as the inner diameter dimension of the tip edge 40 b of the dust lip 40, and is slidably elastically contacted with the outer peripheral surface 10 a of the shaft 10. Further, the convex portion 41 extends in parallel to the axial direction Z of the shaft 10 from the tip edge 40 b of the dust lip 40.

  Since the convex portion 41 extends parallel to the axial direction Z, the rigidity in the axial direction Z is high, and the rigidity of the dust lip 40 in the axial direction Z can be increased. Therefore, it is possible to suppress the tip of the dust lip 40 from being dragged inward by the shaft 10, and as a result, the dust lip 40 is caused to return to the original state by elastic force of the dust lip 40. The separation from the outer peripheral surface 10a can be suppressed. As a result, entry of dust from the outside can be suppressed. Further, since the convex portion 41 is not installed on the entire inner peripheral surface 40a of the dust lip 40, the flexibility of the dust lip 40 is less likely to be lost, and the followability with respect to the shaft eccentricity is less likely to be impaired.

  Further, as shown in FIG. 1, a plurality of convex portions 41 may be provided at equal intervals along the circumferential direction of the shaft 10. By providing a plurality of convex portions 41 at equal intervals along the circumferential direction of the shaft 10, the anisotropy of the followability with respect to the shaft eccentricity can be suppressed.

  FIG. 2 is a partial cross-sectional view showing another example of the configuration of the shaft seal of the present invention. Hereinafter, the configuration of the shaft seal shown in FIG. 2 will be described in detail, but the same components as those in FIG.

  As shown in FIG. 2, the dust lip 40 includes a ring-shaped member 42 having a higher elastic modulus than the dust lip 40 on a sliding surface 40 c that is in sliding contact with the outer peripheral surface 10 a of the shaft 10. The inner peripheral surface of the ring-shaped member 42 has an inner diameter that is substantially the same as the inner diameter of the tip edge 40 b of the dust lip 40, and is slidably elastically contacted with the outer peripheral surface 10 a of the shaft 10. Therefore, the dust attached to the outer peripheral surface 10a of the shaft 10 can be scraped out to the outside by the inner peripheral surface of the ring-shaped member 42, that is, the sliding surface 40c of the dust lip 40.

  Since the ring member 42 has a higher elastic modulus than the dust lip 40, the elastic modulus of the sliding surface 40c of the dust lip 40 can be increased. Therefore, the elastic deformation of the sliding surface 40c of the dust lip 40 can be suppressed, and the sliding surface 40c of the dust lip 40 can be suppressed from separating from the outer peripheral surface 10a of the shaft 10. As a result, entry of dust from the outside can be suppressed. Moreover, since the ring-shaped member 42 is installed on the free end (tip) side of the dust lip 40, the flexibility of the dust lip 40 is less likely to be lost, and the followability to the shaft eccentricity is less likely to be impaired.

  As the ring-shaped member 42, for example, polytetrafluoroethylene (trade name: Teflon (registered trademark)) having a higher elastic modulus than rubber such as nitrile rubber is used. Polytetrafluoroethylene has a lower coefficient of friction and higher hardness (abrasion resistance) than rubbers such as nitrile rubber. Therefore, by using polytetrafluoroethylene as the ring-shaped member 42, it is possible to stably suppress the intrusion of dust over a long period of time.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, as shown in FIG. 1, the convex portion 41 of this embodiment is extended in parallel to the axial direction Z of the shaft 10 from the tip edge 40 b of the dust lip 40. As long as the rigidity in the direction Z can be increased, the installation position is not limited. For example, the installation position may extend in parallel to the axial direction Z of the shaft 10 from the sliding surface 40c of the dust lip 40 shown in FIG. .

  In addition, the main lip 30 of the present embodiment suppresses oil leakage from the inside. However, like the main lip having the above-described conventional configuration, the main lip 30 suppresses oil and gas leakage from the inside. It may be. In this case, the main lip 30 is in sliding contact with the outer peripheral surface 10 a of the shaft 10 in an airtight manner.

It is sectional drawing which showed an example of the structure of the shaft seal of this invention. It is sectional drawing which showed another example of the structure of the shaft seal of this invention. It is sectional drawing which showed an example of the structure of the shaft seal provided with the conventional round type dust lip. It is sectional drawing which showed typically the problem of the shaft seal provided with the conventional scraper type dust strip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 axis | shaft 10a outer peripheral surface of shaft 10 main lip 30a outer peripheral surface of main lip 30 40 dust lip 40a inner peripheral surface of dust lip 40 40 tip edge of dust lip 40 c sliding surface of dust lip 40 convex part 42 ring shape Element

Claims (4)

In the shaft seal provided with an annular duster that suppresses the intrusion of dust from the outside in a state of sliding contact with the outer peripheral surface of the shaft,
The dust lip protrudes obliquely toward the outside toward the inside in the radial direction of the shaft, and has a configuration that becomes thinner toward the tip.
A shaft seal provided with a convex portion extending in parallel to the axial direction of the shaft on the inner peripheral surface of the dust lip.   The shaft seal according to claim 1, wherein a plurality of the convex portions are installed at equal intervals along a circumferential direction of the shaft.   The shaft seal according to claim 1, wherein the dust lip further includes a ring-shaped member having a higher elastic modulus than the dust lip on a sliding surface that is in sliding contact with the outer peripheral surface of the shaft. In the shaft seal provided with an annular duster that suppresses the intrusion of dust from the outside in a state of sliding contact with the outer peripheral surface of the shaft,
The dust lip protrudes obliquely toward the outside toward the inside in the radial direction of the shaft, and has a configuration that becomes thinner toward the tip.
The dust lip is a shaft seal provided with a ring-shaped member having a higher elastic modulus than the dust lip on a sliding surface that is in sliding contact with the outer peripheral surface of the shaft.

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