JPH03260478A - Lip seal device - Google Patents

Abstract

PURPOSE:To absorb center dislocation of a rotary shaft or its swinging by surrounding the elastic deformation part by a guide surface to curve the lip, an end face extending outward in the radial direction, and a cylindrical outside surface extending in the axial direction. CONSTITUTION:A ring-shaped elastic member 5 is equipped with an elastically deforming part 5B having the large wall thickness surrounded by a guide surface 5a which overlaps on that surface of a lip 6 situated on the encapsulated fluid side, i.e. on the left side surface, and bends the lip 6 into a specified shape together with a flange part 4b, an end face 5b which extends outward in the radial direction from near the bore 6b of the lip 6 as shown by an imaginatory line, and a cylindrical outside surface 5c which extends in the axial direction from the position close to the periphery of the lip 6. A space 10 continued circumferentially to a holding member 9 is formed at the periphery of this cylindrical outside surface 5c on its lip 6 side, and the encapsulated fluid side of the surface 5c is continued to the seal part 5A. Thereby the lip 6 is allowed to follow up a rotary shaft 2 in good performance while its center dislocation or swinging is absorbed effectively by the elastically deforming part 5B and the space 10 outside it.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a lip seal device having a lip that slides into contact with a rotating shaft.

"Prior Art" Conventionally, a lip seal device has a case that surrounds a rotary shaft that is rotatably supported, an outer peripheral part is attached to the case, and an inner peripheral part is curved toward the sealing fluid side. a lip that is in sliding contact with the outer circumferential surface of the rotating shaft; and an annular shape whose outer circumferential portion is attached to the case and overlaps the sealed fluid side surface of the lip to urge the inner circumferential portion of the lip toward the rotating shaft. There is known an annular elastic member in which the inner circumferential portion of the annular elastic member is brought into sliding contact with the outer circumferential surface of the rotating shaft (Japanese Utility Model Publication No. Sho 62-181759).

In this type of lip seal device, the lip is usually manufactured from a disc-shaped PTFE with excellent wear resistance, and the annular elastic member is manufactured from a disc-shaped relatively soft rubber. The elasticity of the lip urges the inner circumferential portion of the lip toward the rotating shaft to bring it into close contact.

``Problems to be Solved by the Invention'' However, when the annular elastic member is formed into a disk shape, and the inner peripheral portion thereof is curved toward the sealed fluid side and overlapped with the sealed fluid side surface of the lip, This makes it easier for the pressure of the sealing fluid to act on the inner peripheral portion of the lip via the annular elastic member.

If the annular elastic member is made relatively soft, when the pressure of the sealing fluid increases, the inner periphery of the lip will come into tight contact with the rotating shaft, reducing its wear resistance. If the member is made relatively hard, the lip will not be able to sufficiently follow the misalignment or runout of the rotating shaft, and there is a risk of leakage.

In view of such circumstances, the present invention has been developed to prevent the wear resistance of the lip from decreasing even when the pressure of the sealed fluid increases, and to sufficiently follow the misalignment and runout of the rotating shaft to prevent leakage. To provide a lip seal device that prevents this from occurring.

"Means for Solving the Problems" That is, the present invention includes a case surrounding a rotatable shaft that is rotatably supported, an outer peripheral portion being attached to the case,
and a lip whose inner circumferential portion is curved toward the sealed fluid side and is in sliding contact with the outer circumferential surface of the rotary shaft, and whose outer circumferential portion is attached to the case and superimposed on the sealed fluid side surface of the lip. A lip seal device comprising an annular elastic member that urges an inner peripheral portion toward the rotation shaft, wherein the annular elastic member overlaps at least a sealed fluid side surface of the lip to curve the lip into a predetermined shape. providing an elastic deformation portion surrounded by a guide surface, an end surface extending radially outward from near the inner circumference of the lip, and a cylindrical peripheral surface extending axially from a position close to the outer circumference of the lip; Furthermore, a space is formed on the lip side outer periphery of the cylindrical circumferential surface, and the sealed fluid side of the cylindrical circumferential surface is attached to the case.

"Operation" According to the above configuration, the end surface forming the elastic deformation portion extends radially outward from near the inner peripheral portion of the lip, and the elastic deformation portion is formed closer to the lip than the end surface. Even when receiving the pressure of the sealing fluid, the elastic deformation portion hardly brings the inner peripheral portion of the lip into close contact with the rotating shaft, and therefore the influence of pressure fluctuations of the sealing fluid can be reduced.

The elastic deformation portion includes a guide surface that curves the lip;
Since it is surrounded by an end surface extending outward in the radial direction and a cylindrical peripheral surface extending in the axial direction, it can be manufactured within a relatively thick wall in the radial direction, and therefore the elastic deformation part of the thick wall itself has a large The contraction and expansion can absorb the misalignment and runout of the rotating shaft. In addition, since a space is formed on the outer periphery of the lip side of the elastically deformable portion, the elastically deformable portion can freely curve within that space, and therefore the elastically deformable portion itself can undergo large contractions and expansions. At the same time, since the lip can be made to follow the rotating shaft well while effectively absorbing misalignment and runout of the rotating shaft, leakage can be well prevented.

``Embodiment'' The present invention will be described below with reference to the illustrated embodiment. A rotating shaft 2 is rotatably supported by passing through a stepped hole la formed in a housing 1, and the inner circumferential surface of the stepped hole 1a and A lip seal device 3 according to the present invention seals between the rotary shaft 2 and the outer circumferential surface thereof. The lip seal device 3 includes a metal case 4, a rubber annular elastic member 5 press-fitted into the case 4, and a PTFE lip 6.

The case 4 is formed into a ring shape so as to surround the rotation shaft 2, and its axial cross-sectional shape includes a cylindrical portion 4a extending in the axial direction and a bend at the right end side of the cylindrical portion 4a. The flange portion 4b is bent and extends inward in the radial direction, and the flange portion 4b extends while being gently curved toward the left sealing fluid side, forming a cross-sectional shape. A rubber seal part 7 is attached to the outer periphery of the cylindrical part 4a by vulcanization or adhesive, and when the lip seal device 3 is assembled to the housing l, the seal part 7 is attached to the inner peripheral surface of the stepped hole 1a. This allows the area to be sealed by bringing it into close contact with the area.

The lip 6 is formed into a thin disk shape, and its radially outer circumferential portion 6a is accommodated within the cylindrical portion 4a of the case 4, and its right surface is attached to the left surface of the flange portion 4b of the case 4. The lip 6 is polymerized and gently curved toward the sealed fluid side, and further curved greatly from the inner peripheral end of the flange portion 4b toward the sealed fluid side to bring the inner peripheral portion 6b of the lip 6 into elastic contact with the outer peripheral surface of the rotating shaft 2. , the sealing fluid present on the left side of the lip 6 is prevented from leaking to the atmosphere side on the right side.

In this embodiment, an annular groove 8 continuous in the circumferential direction is formed in the inner peripheral portion 6b of the lip 6 that makes sliding contact with the rotating shaft 2.

Further, the annular elastic member 5 is provided with a cylindrical presser member 9 embedded in its outer circumferential portion, and the seal portion 5A on the outer circumferential side of the presser member 9 is press-fitted into the cylindrical portion 4a of the case 4. The annular elastic member 5 is integrally connected to the case 4. In this state, the right end of the presser member 9 protrudes outward from the annular elastic member 5 and engages in an engagement groove 60 formed on the left end surface of the outer peripheral portion 6a of the lip 6, and the presser member 9 The right end of the case 4 and the flange part 4 of the case 4
By holding the outer peripheral portion 6a of the lip 6 between
This prevents the lip 6 from falling radially inwardly.

Further, the annular elastic member 5 is superimposed on the sealed fluid side surface, that is, the left side surface of the lip 6, and is superimposed on the flange portion 4.
a guide surface 5 that curves the lip 6 into a predetermined shape together with b;
a, an end surface 5b extending radially outward from the vicinity of the inner circumference 6b of the lip 6 as shown by the imaginary line, and a cylindrical circumferential surface 5c extending axially from a position close to the outer circumference of the lip 6. The elastic deformation part 5B within the thickness is surrounded by
It is equipped with

A circumferentially continuous space lO is formed between the outer circumference of the cylindrical circumferential surface 5c on the lip 6 side and the pressing member 9, and the sealed fluid side of the cylindrical circumferential surface 5c is connected to the seal portion. 5A, and further forms an auxiliary lip portion 5C extending obliquely forward toward the rotating shaft 2 from the radially inner portion of the end surface 5b. The tip of this auxiliary lip portion 5C comes into sliding contact with the rotating shaft 2, and this portion and the lip 6 provide a double sealing effect.

According to the above configuration, the guide surface 5a of the elastic deformation portion 5B
The lip 6 is curved into a desired predetermined shape, and the inner circumferential portion 6b of the lip 6 is brought into elastic contact with the outer circumferential surface of the rotating shaft 2. Since the elastically deformable portion 5B is formed within the thickness, the elastically deformable portion 5B itself can contract and expand significantly, thereby absorbing misalignment and center runout of the rotating shaft 2. .

In addition, since a space 10 is formed on the outer periphery of the elastically deformable portion 5B on the lip 6 side, the elastically deformable portion 5B can freely deform into the space 10, and therefore the elastically deformable portion 5B can be freely deformed into the space 10. Coupled with the fact that the lip 6 itself can greatly contract and expand, the lip 6 can be made to follow the rotating shaft 6 well while effectively absorbing the misalignment and runout of the rotating shaft 2, thereby improving leakage. It can be prevented.

Furthermore, the end surface 5b forming the elastic deformation portion 5B is
extends radially outward from the vicinity of the inner circumference 6b of the lip 6, and the elastically deformable portion 5B is formed closer to the lip 6 than the end surface, so that the elastically deformable portion 5B receives the pressure of the sealing fluid. Even if the inner periphery s6b of the lip 6 is not brought into close contact with the rotating shaft 2, the influence of pressure fluctuations of the sealing fluid on the adhesion between the inner periphery s6b and the rotating shaft 2 can be reduced. Therefore, it is possible to prevent the abrasion resistance from becoming too large due to the adhesion force or from increasing leakage due to insufficient adhesion force, and it is possible to obtain a stable sealing action.

In the above embodiment, the annular elastic member 5 is provided with an auxiliary lip portion 5.
C is formed so that a double sealing effect can be obtained together with the lip 6, but if necessary, an auxiliary lip portion 5C can be formed.
may be omitted. Further, in the above embodiment, the space IO is continuous in the circumferential direction, but the seal portion 5A and the cylindrical peripheral surface 5
C may be connected with reinforcing struts extending in the radial direction, and the space lO may be interrupted in the circumferential direction.

Furthermore, if the engagement portion between the presser member 9 and the engagement groove 6C is formed into a comb-teeth shape, rotation of the lip 6 can be more effectively prevented, and the seal portion 5A of the annular elastic member 5 can be attached to the case 4. Instead of being press-fitted into the cylindrical portion 4a, the seal portion 5A may be integrally connected to the case 4 by vulcanization. In particular, when the seal portion 5A is integrally connected to the case 4 by vulcanization, the pressing member 9 can be omitted.

"Effects of the Invention" As described above, according to the present invention, the lip can effectively follow the rotation axis while effectively absorbing misalignment and center runout of the rotation axis by the elastic deformation part and the space outside the elastic deformation part. Moreover, since the influence of pressure fluctuations of the sealing fluid can be reduced, it is possible to obtain a stable and good sealing effect.

[Brief explanation of drawings]

The figure is a sectional view showing one embodiment of the present invention. 1...Housing 3...Lip seal device 5.--Annular elastic member 5C...Auxiliary lip part 5b... end face 6...Lip 6b...Inner peripheral part 2...Rotation axis 4...Case 5B...Elastic deformation part 5a... Information surface 5c...Cylindrical peripheral surface 6a...Outer periphery 10...Space

Claims (1)

[Scope of Claims] A case surrounding a rotating shaft rotatably supported;
a lip whose outer peripheral part is attached to the case and whose inner peripheral part is curved toward the sealing fluid side and slidably contacts the outer peripheral surface of the rotating shaft; and whose outer peripheral part is attached to the case and which seals the fluid of the lip A lip seal device comprising: an annular elastic member that is superimposed on a side surface of the lip and urges an inner peripheral portion of the lip toward the rotating shaft; a guide surface for bending the lip into a predetermined shape; an end surface extending radially outward from near the inner circumference of the lip; and a cylindrical circumferential surface extending axially from a position close to the outer circumference of the lip. What is claimed is: 1. A lip seal device comprising: an elastically deformable portion surrounded by a cylindrical circumferential surface; furthermore, a space is formed on the lip-side outer periphery of the cylindrical circumferential surface; and the sealing fluid side of the cylindrical circumferential surface is attached to the case.