JP2008309273A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device having reduced friction against a shaft while avoiding negative pressure in an annular space formed between a main lip and a sub lip. <P>SOLUTION: The main lip 4 on the seal side and the sub lip 5 on the atmosphere side are integrally formed of a rubber elastic body. Protrusions 14 are provided at a plurality of positions on the front end inner peripheral face of the sub lip for avoiding negative pressure in the annular space formed between both lips during the rotation of the shaft 3. The number of the protrusions at the plurality of positions equally spaced in the rotating direction of the shaft is an odd number. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the sealing device such as an oil seal, for example, when negative pressure is generated in the annular space generated between the main lip on the sealing fluid side and the sub lip on the atmosphere side as the shaft rotates, both the lips are The present invention relates to a sealing device that is in a state of being attracted to each other and prevents an excessive contact pressure from being generated on a shaft.

  Conventionally, in an oil seal having a main lip on the sealing fluid side and a sub lip (dust lip) on the atmosphere side, and these main lip and sub lip are integrally formed of a rubber-like elastic body, The fluid in the annular space formed in the cylinder is sucked into the main lip due to the sealing action of the main lip, and negative pressure is generated. Since no fluid flows into the annular space, the negative pressure in the space increases, and this negative pressure pulls both lips toward the annular space, increasing the contact pressure on the shaft, As a result, the portion that contacts the shaft of the lip generates heat and causes a problem in sealing performance.

In order to solve the above-described problems, a plurality of protrusions are provided on the peripheral side surface that contacts the shaft of the secondary lip, thereby forming a passage between the peripheral surface of the shaft, the protruding portion, and the side surface of the protruding portion. Since the seal portion is separated from the shaft, there has been proposed one in which the negative pressure is eliminated through communication between the atmosphere side and the annular space (see Patent Document 1).
Japanese Utility Model Publication No. 62-12933

However, in the one disclosed in Patent Document 1, no particular consideration is given to the arrangement of the plurality of protrusions provided on the sub lip, and as a result, when the protrusions are arranged at positions that oppose each other by 180 °, the above-described facing is performed. As a result, the shaft is strongly clamped by the protruding protrusions, and there is a problem that the friction against the lip during rotation of the shaft increases.
The present invention has been invented in view of the above points, and eliminates the negative pressure in the annular space formed between the main lip and the sub lip and seals to reduce the friction with respect to the shaft. The purpose is to provide a device.

  In order to achieve the above object, the sealing device according to the present invention is such that the main lip on the sealing side and the sub lip on the atmosphere side are integrally formed of a rubber-like elastic body, and the main lip and the sub lip are attached when the shaft is mounted. In order to eliminate the negative pressure generated in the annular space formed between the two, the sealing device provided with projections at a plurality of locations on the inner peripheral surface of the tip of the sub lip, at a plurality of locations on the inner peripheral surface of the tip of the sub lip This is characterized in that the number of protrusions provided is an odd number at equal intervals in the rotation direction of the shaft.

  The sealing device according to the present invention includes an annular space formed between the two lips when a shaft is mounted on a sealing device having a main lip and a sub lip integrally formed of a rubber-like elastic body. Even when a negative pressure is generated as the shaft rotates, protrusions are provided at a plurality of locations on the inner peripheral surface of the tip of the sub lip, so that the protrusions are in contact with the shaft and the atmosphere between the shaft and the side surfaces of the protrusions A gap serving as a passage communicating with the side is formed, and the air passage and the annular space are communicated with each other by the formed passage to eliminate the negative pressure.

  Further, in the present invention, since the number of protrusions provided at a plurality of locations on the inner peripheral surface of the tip portion of the sub lip is an odd number at equal intervals in the rotation direction of the shaft, the protrusion provided on the sub lip is provided. Are not opposed to each other at 180 °, and there is no fear that the shaft is strongly pinched by the lip, so that the friction during rotation of the shaft can be kept low.

  Embodiments of the present invention will be described with reference to the drawings. A sealing device 1 such as an oil seal is mounted between a housing 2 and a shaft 3, and a main lip 4 on the sealing fluid side M and a sub lip (dust lip) 5 on the atmosphere side C are rubber-like elastic bodies 10. It is molded integrally. A rubber-like elastic body 10 is baked and fixed on the outer periphery of the cylindrical portion 9 of the metallic reinforcing ring 6 with the inner peripheral end 8 of the flange portion 7 of the L-shaped metallic reinforcing ring 6 embedded, and the main lip 4 is The inner peripheral end portion of the flange portion 7 of the metallic reinforcing ring 6 is formed at the distal end portion of the waist portion 12 extending to the sealing fluid side from the base portion 11 embedded in the rubber-like elastic body 10, and the distal end thereof is a shaft. The outer peripheral surface of 3 has a predetermined fastening allowance so as to be slidably sealed and sealed with a sealing fluid. Reference numeral 13 denotes, for example, a coil spring that is attached to the outer periphery of the main lip 4 and applies a tension force.

  A sub lip 5 is formed to seal the atmosphere side from the base portion 11 toward the atmosphere side in the axial direction. The sub lip 5 is in sliding contact with the shaft 3 with a predetermined tightening allowance so that dust and the like enter the atmosphere. Blocking. In this embodiment, spherical projections 14, 14, 14 are provided at a plurality of locations on the inner peripheral surface of the tip of the sub lip 5, and the number of the projections 14 is equal to the rotational direction of the shaft. An odd number of intervals is used. In the present embodiment, the protrusions 14 are provided at three positions at intervals of 120 °.

  As described above, in the present embodiment, the main lip 4 on the sealed fluid side M and the sub lip 5 on the atmosphere side C are provided, and the tips of these lips 4 and 5 come into contact with the shaft with a predetermined allowance. This seals the space between the sealed fluid side and the atmosphere side. Protrusions 14, 14, 14 are provided at a plurality of locations on the inner peripheral surface of the tip portion of the sub lip 5, and the shaft 3 rotates. Sometimes, when a negative pressure is generated in the annular space between the main lip 4 and the sub lip 5, the projections 14, 14, 14 come into contact with the shaft 3, so that the shaft 3 and the side surface of the projection 14 are between A gap 15 is formed as a passage communicating with the atmosphere side, and thereby the negative pressure is eliminated.

  Since the number of projections 14 provided at a plurality of locations on the inner peripheral surface of the tip end portion of the sub lip 5 is an odd number at equal intervals in the rotation direction of the shaft 3, the projections provided at the plurality of locations are opposed at 180 °. Therefore, the shaft 3 is not strongly clamped, and the friction during rotation of the shaft 3 can be kept low. Further, by forming the above-described protrusion 14 into a spherical shape, the protrusion 14 can be brought into contact with the shaft 3 smoothly, and the friction can be reduced.

  In the present embodiment, the number of the protrusions 14 described above is three at an equal interval of 120 ° in the rotation direction of the shaft 3, but is not limited to this, and an odd number of three or more, for example, five , 7 or more can be used.

The half sectional view of the sealing device of the present invention. Explanatory drawing which the sub lip of the sealing device of this invention formed the channel | path.

Explanation of symbols

1 sealing device 4 main lip 5 sub lip 14 protrusion 15 gap (passage)

Claims (1)

The main lip on the sealing side and the sub lip on the atmosphere side are integrally formed of a rubber-like elastic body, so that the negative pressure generated in the annular space formed between the main lip and the sub lip when the shaft is mounted is eliminated. In the sealing device provided with protrusions at a plurality of locations on the inner peripheral surface of the tip portion of the sub lip,
2. A sealing device according to claim 1, wherein the number of protrusions at a plurality of locations provided on the inner peripheral surface of the tip end portion of the sub lip is an odd number at equal intervals in the rotational direction of the shaft.

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