Sealing device

Abstract

To improve sealability between a housing and a shaft member.SOLUTION: A sealing device 6 includes: a lip seal 7 having a cylindrical part 7a in a substantially cylindrical shape and an annular projecting part 7b projecting outward from one end of the cylindrical part 7a, forming a first inclined surface 7c that gradually inclines outward toward the projection part 7b over the entire circumference in a region adjacent to the projection part 7b on an outer circumferential surface of the cylindrical part 7a, making an inner circumferential surface of the cylindrical part 7a face a shaft member 3 and attaching one end of the cylindrical part 7a to the shaft member 3 while facing a projection part 5b of a housing 5; and an O-ring 9 inserted in a compressed state between the inner circumferential surface of a circumferential wall part 5a of the housing 5 and the cylindrical part 7a of the lip seal 7.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a sealing device that seals a gap formed between a housing and a shaft member. [Background technology]

[0002] The sealing device disclosed in Patent Document 1 seals a gap formed between a shaft member and a housing having a groove. This sealing device includes an O-ring that contacts the bottom surface of the housing groove and the groove side surface on the low-pressure side, and a sealing ring with a generally trapezoidal cross section that contacts the O-ring and the shaft member. In this sealing device, the O-ring and sealing ring are pressed against the groove side surface on the low-pressure side by fluid pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2005-504237 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the pressure acting on the shaft member from the sealing ring does not change much in response to the fluid pressure, so when the fluid pressure increases, the fluid is likely to leak from between the sealing ring and the shaft member.

[0005] The present disclosure has been made in view of the above points, and an object thereof is to improve the sealing performance between the housing and the shaft member. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a first aspect of the present disclosure is a sealing device having an axial member, a cylindrical peripheral wall portion, and an annular protrusion portion protruding inward from the peripheral wall portion, and sealing an annular gap formed between the axial member and a housing surrounding the axial member from the outside, the sealing device having a cylindrical portion and an annular protrusion portion protruding outward from one end of the cylindrical portion, and an inclined surface that gradually slopes outward toward the protrusion portion is formed around the entire circumference in an area adjacent to the protrusion portion on the outer surface of the cylindrical portion, the inner surface of the cylindrical portion facing the axial member and the one end of the cylindrical portion facing the protrusion portion of the housing, a lip seal that is attached to the axial member, and an O-ring that is inserted in a compressed state between the inner surface of the circumferential wall portion of the housing and the tubular portion of the lip seal.

[0007] As a result, when the fluid pressure pushing the O-ring toward the protruding portion of the lip seal increases, the pressure acting from the O-ring to the inclined surface also increases, and the surface pressure acting from the cylindrical portion of the lip seal to the shaft member also increases. Therefore, even when the fluid pressure increases, it is easy to ensure sealing between the housing and the shaft member.

[0008] Furthermore, because the gap between the cylindrical portion of the lip seal and the peripheral wall of the housing gradually narrows along the inclined surface, the O-ring can be moved toward the protruding portion along the inclined surface of the lip seal by fluid pressure, thereby increasing the pressure acting from the O-ring on the inclined surface of the lip seal. This increases the pressure acting on the shaft member from the cylindrical portion of the lip seal, improving the seal between the housing and the shaft member. Furthermore, because the pressure acting from the O-ring on the peripheral wall of the housing can be increased, the O-ring can be more firmly attached to the peripheral wall of the housing, preventing the O-ring from rotating with the shaft member.

[0009] A second aspect of the present disclosure is characterized in that, in the sealing device according to the first aspect, the surface of the protruding portion of the lip seal that faces the protruding portion of the housing is inclined toward the other axial end of the cylindrical portion toward the tip side of the protruding portion.

[0010] As a result, when the surface of the housing protrusion facing the lip seal's protruding portion is perpendicular to the shaft, even when the axial end of the cylindrical portion of the lip seal is abutted against the housing protruding portion, the tip of the lip seal's protruding portion will be separated from the housing protruding portion. From this state, fluid pressure can be applied to the O-ring in a direction pushing toward the lip seal's protruding portion, causing the protruding portion to rotate so that the tip of the protruding portion approaches the protruding portion. This increases the surface pressure acting on the shaft from the vicinity of the base end of the protruding portion of the cylindrical portion, further improving the sealing performance between the housing and the shaft.

[0011] A third aspect of the present disclosure is characterized in that, in the sealing device according to the first aspect, a circumferentially extending protrusion is formed on the inner surface of the cylindrical portion of the lip seal, and an end face of the protrusion intersects with a perpendicular line that intersects perpendicularly with the inclined surface.

[0012] This allows the pressure acting on the inclined surface of the lip seal from the O-ring to be concentrated on the shaft member from the end face of the protrusion, further improving the sealing performance between the housing and the shaft member. [Effects of the Invention]

[0013] According to the present disclosure, the sealing performance between the housing and the shaft member can be improved. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a plan view of an apparatus equipped with a sealing device according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is an enlarged view of part III in FIG. [Figure 4] FIG. 4 is a view equivalent to FIG. 3 of the second embodiment in a state where no fluid pressure is applied to the O-ring. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0016] First Embodiment 1 and 2 show the configuration of a device 1 equipped with a sealing device 6 according to a first embodiment of the present disclosure. The sealing device 6 seals an annular gap G formed between a metal shaft member 3 and a metal housing 5 that surrounds the shaft member 3 from the outside.

[0017] The shaft member 3 is formed in a cylindrical shape and is rotated by a driving device (not shown).

[0018] The housing 5 has a cylindrical peripheral wall 5a and an annular plate-like protruding portion 5b that protrudes inward with a constant thickness from one end of the peripheral wall 5a. Both surfaces of the protruding portion 5b are perpendicular to the shaft member 3.

[0019] The sealing device 6 includes an annular lip seal 7 having a substantially L-shaped cross section, and an O-ring 9 having a circular cross section. The lip seal 7 and the O-ring 9 are made of an elastic material such as an elastomer.

[0020] As shown in Fig. 3, the lip seal 7 has a generally cylindrical cylindrical portion 7a and an annular plate-like protruding portion 7b that protrudes outward from one axial end of the cylindrical portion 7a with a constant thickness. A first inclined surface 7c that gradually slopes outward toward the protruding portion 7b is formed around the entire circumference in a region of the outer peripheral surface of the cylindrical portion 7a adjacent to the protruding portion 7b. An annular protrusion 7d that protrudes slightly outward toward the outer peripheral side is formed around the entire circumference at a distance from the first inclined surface 7c on the other axial end of the cylindrical portion 7a (the end on the side where the protruding portion 7b is not formed). A second inclined surface 7e that slopes toward the other axial end of the cylindrical portion 7a (away from the protruding portion 7b) of the protrusion 7d is formed on the side surface of the protrusion 7d on the protruding portion 7b side (the one axial end of the cylindrical portion 7a) toward the protruding direction. A first protrusion 7g having a trapezoidal cross section and extending in the circumferential direction is formed around the entire circumference on the inner peripheral surface of the other axial end of the cylindrical portion 7a. Both side surfaces of the first protrusion 7g form third inclined surfaces 7h that slope outward toward the base end. A second protrusion 7i having a substantially isosceles trapezoidal cross section and extending in the circumferential direction is formed around the entire circumference on the inner peripheral surface near the one axial end of the cylindrical portion 7a. The end surfaces of the second protrusion 7i are arranged so as to intersect with a perpendicular line VL that perpendicularly intersects with the first inclined surface 7c. Both side surfaces of the second protrusion 7i form fourth inclined surfaces 7j that slope outward toward the base end. The inner peripheral surface of the one axial end of the cylindrical portion 7a forms a fifth inclined surface 7k that gradually recedes radially outward toward the one axial end of the cylindrical portion 7a. The fourth inclined surface 7j forms a part of the fifth inclined surface 7k.

[0021] The lip seal 7 configured as described above is attached to the shaft member 3 with the inner peripheral surface of the cylindrical portion 7a facing the outer peripheral surface of the shaft member 3 and the end face of the one axial end of the cylindrical portion 7a (the end on the protruding portion 7b side) abutting against the side face of the protruding portion 5b of the housing 5. In other words, the one axial end of the cylindrical portion 7a (the end on the protruding portion 7b side) faces the protruding portion 5b of the housing 5. In this attached state, the end faces of the first protrusion 7g and the second protrusion 7i of the cylindrical portion 7a abut against the outer peripheral surface of the shaft member 3, and the protruding portion 7b abuts against the side face of the protruding portion 5b of the housing 5 over the entire protruding direction. In addition, the O-ring 9 is inserted in a compressed state between the inner peripheral surface of the peripheral wall portion 5a of the housing 5 and the cylindrical portion 7a of the lip seal 7.

[0022] When fluid pressure is applied to the O-ring 9 in a direction pushing the protruding portion 7b toward the shaft member 3 and the housing 5 with the sealing device 6 attached as described above (the direction indicated by arrow X1 in FIG. 3), the protruding portion 7b is pushed by the O-ring 9 and pressed against the protruding portion 5b of the housing 5. Furthermore, pressure is applied from the O-ring 9 to the first inclined surface 7c of the lip seal 7 in the direction indicated by arrow X2 in FIG. 3 (a direction perpendicular to the first inclined surface 7c), increasing the pressure acting on the shaft member 3 from the end face of the second protrusion 7i of the cylindrical portion 7a. Furthermore, since the gap between the cylindrical portion 7a of the lip seal 7 and the peripheral wall portion 5a of the housing 5 gradually narrows along the first inclined surface 7c, when the O-ring 9 moves along the first inclined surface 7c toward the protruding portion 7b due to the fluid pressure, the pressure acting from the O-ring 9 on the first inclined surface 7c of the lip seal 7 increases. Therefore, the pressure acting on the shaft member 3 from the cylindrical portion 7a of the lip seal 7 is increased, improving the sealing performance between the housing 5 and the shaft member 3. Furthermore, the pressure acting on the peripheral wall portion 5a of the housing 5 from the O-ring 9 (pressure in the direction indicated by arrow X3 in FIG. 3) is also increased, so that the O-ring 9 is more firmly attached to the peripheral wall portion 5a of the housing 5 and the O-ring 9 is prevented from rotating together with the shaft member 3.

[0023] Furthermore, when the fluid pressure acting in a direction pressing the O-ring 9 toward the protruding portion 7b increases, the pressure acting from the O-ring 9 to the first inclined surface 7c increases, and the surface pressure acting from the cylindrical portion 7a of the lip seal 7 to the shaft member 3 also increases. Therefore, even if the fluid pressure increases, it is easy to ensure sealing between the housing 5 and the shaft member 3.

[0024] Therefore, according to the first embodiment, the second protrusions 7i are provided on the inner circumferential surface of the cylindrical portion 7a of the lip seal 7, so that the pressure acting from the O-ring 9 on the cylindrical portion 7a can be concentrated on the shaft member 3 through the second protrusions 7i. Furthermore, because the end faces of the second protrusions 7i are arranged so as to intersect with the perpendicular line VL that perpendicularly intersects with the first inclined surface 7c, the pressure acting from the O-ring 9 on the first inclined surface 7c can be concentrated on the shaft member 3 through the second protrusions 7i. This further improves the sealing performance between the housing 5 and the shaft member 3.

[0025] Second Embodiment FIG. 4 is a view corresponding to FIG. 3 of the second embodiment. In the second embodiment, the protruding portion 7b of the lip seal 7 gradually becomes thinner toward its tip. The surface of the protruding portion 7b of the lip seal 7 facing the protruding portion 5b of the housing 5 (the surface of the protruding portion 7b on the axial one end side of the cylindrical portion 7a) is inclined toward the other axial end side of the cylindrical portion 7a toward the tip side of the protruding portion 7b. When the sealing device 6 is attached to the shaft member 3 and the housing 5 and no fluid pressure is applied to the O-ring 9, the axial one end of the cylindrical portion 7a of the lip seal 7 abuts against the protruding portion 5b of the housing 5, but the tip end of the protruding portion 7b of the lip seal 7 is separated from the protruding portion 5b of the housing 5. In other words, when no fluid pressure is applied to the O-ring 9, a gap S is formed between the tip end of the protruding portion 7b of the lip seal 7 and the protruding portion 5b of the housing 5. When fluid pressure is applied to the O-ring 9 in this state in a direction pushing it toward the protruding portion 7b, pressure is applied from the O-ring 9 to the protruding portion 7b in the direction of arrow X4. This causes the protruding portion 7b to rotate in the direction of arrow X5 so that the tip of the protruding portion 7b approaches the protrusion 5b. This causes a force to press the vicinity of the base end of the protruding portion 7b on the cylindrical portion 7a of the lip seal 7 toward the shaft member 3, increasing the surface pressure acting on the shaft member 3 from the vicinity of the base end of the protruding portion 7b on the cylindrical portion 7a, i.e., from the end face of the second protrusion 7i. This further improves the sealing performance between the housing 5 and the shaft member 3.

[0026] Other configurations and operations are the same as those in the first embodiment, so the same components are given the same reference numerals and detailed descriptions thereof are omitted.

[0027] In the above-mentioned embodiments 1 and 2, the first protrusion portion 7g and the second protrusion portion 7i are provided on the inner surface of the cylindrical portion 7a of the lip seal 7, but the first protrusion portion 7g and the second protrusion portion 7i may not be provided, and the entire inner surface of the cylindrical portion 7a of the lip seal 7 may be formed flat. [Industrial Applicability]

[0028] INDUSTRIAL APPLICABILITY The present disclosure is useful as a sealing device for sealing a gap formed between a housing and a shaft member. [Explanation of symbols]

[0029] 3. Shaft components 5 ハウジング 5a Peripheral wall 5b protrusion 6 Sealing device 7 リップシール 7a cylindrical part 7b Zhang Chubu 7c First inclined surface 7i Second protrusion G Gap VL vertical line

Claims

1. A sealing device that seals an annular gap formed between a shaft member, a housing that has a cylindrical peripheral wall portion, and an annular protrusion that protrudes inward from the peripheral wall portion and surrounds the shaft member from the outside, a lip seal having a cylindrical portion and an annular protruding portion protruding outward from one axial end of the cylindrical portion, wherein an inclined surface that gradually slopes outward toward the protruding portion is formed around the entire circumference in an area of ​​the outer peripheral surface of the cylindrical portion adjacent to the protruding portion, and wherein an inner peripheral surface of the cylindrical portion faces the shaft member and the one axial end of the cylindrical portion faces the protruding portion of the housing; a sealing device comprising an O-ring inserted in a compressed state between the inner peripheral surface of the peripheral wall portion of the housing and the cylindrical portion of the lip seal;

2. The sealing device according to claim 1, A sealing device characterized in that the surface of the protruding portion of the lip seal facing the protruding portion of the housing is inclined toward the other axial end of the cylindrical portion toward the tip side of the protruding portion.

3. The sealing device according to claim 1, A sealing device characterized in that a circumferentially extending protrusion portion is formed on the inner surface of the cylindrical portion of the lip seal, and the end face of the protrusion portion intersects with a perpendicular line that intersects perpendicularly with the inclined surface.

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