JP2000055208A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a sufficient pump function from an initial condition until after the progress of abrasion. SOLUTION: The atmosphere side tilted surface 8 of a lip tip part 4 is provided with a first boat-bottom screw projection 9: gradually increasing its projection height toward the atmosphere side from a sealed object fluid side end part, to position the maximum height at the atmosphere side end part, and a second boat-bottom screw projection 10: gradually increasing its projection height toward the sealed object fluid side from the atmospher side end part, to position the maximum height at the sealed object fluid side end part. Consequently pump suction quantity can be improved over the wide range from an initial condition until after abrasion to obtain stable sealing performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device such as an oil seal used for a shaft sealing portion of various devices, and more particularly, to a device having a threaded protrusion on a lip tip at an atmosphere side inclined surface.

[0002]

2. Description of the Related Art As a conventional sealing device of this type, for example, the one shown in FIG. 2 is known (for example, see Japanese Patent Application Laid-Open No. 9-42436).

That is, this sealing device 100 seals an annular gap between a housing 101 as two members which are assembled concentrically and relatively rotatably and a rotating shaft 102 inserted into the housing 101. Annular seal body 10 fitted on the inner periphery of housing 101
3 and a seal lip 105 extending from the seal body 103 to the fluid side O to be sealed and having a lip tip 104 slidably and sealingly contacting the rotating shaft 102.

[0004] The lip tip 104 has a mountain-shaped cross section, and the fluid-to-be-sealed inclined surface 107 which inclines from the top 106 toward the fluid-to-be-sealed O in the axial direction so as to gradually decrease in diameter.
An air-side inclined surface 108 that is inclined from the top 106 toward the atmosphere-side in the axial direction so as to have a gradually smaller diameter, and a plurality of screw protrusions 109 linearly formed on the air-side inclined surface 108 in the circumferential direction. Was provided.

[0005] The screw projection 109 is arranged such that the protruding height gradually increases from the fluid-side end 109a toward the atmosphere to the atmosphere side, and the maximum height is located at the atmosphere-side end 109b. However, even if the wear progresses, the remaining portion of the screw protrusion 109 is brought into contact with the screw to provide a screw pump effect.

[0006]

However, in the case of the above-mentioned conventional sealing device, when the wear progresses to some extent as compared with the initial state, the portion where the protrusion of the screw protrusion 109 is higher comes into contact, so that the screw pump function is provided. And the screw pump function is low in the initial stage without wear.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and to provide a sealing device with a screw projection having a stable pump function from an initial state to after abrasion has progressed. The purpose is to do so.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention seals an annular gap between two members concentrically and rotatably assembled with each other.
An annular seal body attached to one of the members,
A seal lip extending from the seal body toward the fluid to be sealed and having a lip tip slidably sealingly contacting the other of the two members, the lip tip having a mountain-shaped cross section, In a sealing device having an atmosphere-side inclined surface that is inclined so as to gradually become smaller in diameter in the axial direction toward the atmosphere side, and a plurality of screw protrusions provided on the atmosphere-side inclined surface, the screw protrusion has a protruding height of sealing. The first height where the maximum height is gradually increased from the target fluid side end toward the atmosphere side and the maximum height is located at the atmosphere side end
And a second screw projection whose protrusion height gradually increases from the atmospheric end toward the sealed fluid side and whose maximum height is located at the sealed fluid end. It is characterized by.

In the initial state and the initial stage of wear, the top of the tip of the lip is tightly contacted over the entire circumference to form a seal portion, and at the same time, only the end of the first screw projection having a low projection height on the fluid side to be sealed is used. Instead, the end of the second screw protrusion having a high protruding height on the side of the fluid to be sealed comes into contact with the second screw protrusion to exhibit the screw pump function. Since the end of the tall second screw protrusion on the side of the fluid to be sealed comes into contact, the suction amount is increased from the initial state.

As the wear progresses, the end of the second screw protrusion to be sealed on the side of the fluid to be sealed wears, and the pumping action of the second screw protrusion decreases. As the wear proceeds, the protrusion height of the first screw protrusion decreases. The pumping action of the first screw protrusion is enhanced by the contact of the high part, and a stable sealing performance can be obtained from the initial state to after the wear.

By arranging the first screw projections and the second screw projections alternately or every few screws, the pumping function can be efficiently operated.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sealing device according to a first embodiment of the present invention.

This sealing device seals an annular gap between a housing 1 as two members which are mounted concentrically and relatively rotatably and a rotating shaft 2 inserted into the housing 1. An annular seal body 3 fitted on the inner circumference, and a lip tip 4 extending from the seal body 3 to a fluid side O to be sealed such as oil, water, chemicals, air or the like.
A seal lip 5 made of a rubber-like elastic material, which slidably and sealingly contacts the rotating shaft 2, and a rubber-like elastic lip extending from the seal body 3 to the atmosphere side so that the tip of the lip slidably contacts the rotating shaft 2. And a dust lip 15 made of a material.

The seal body 3 includes a metal ring 3 having an L-shaped cross section.
1 and a rubber-like elastic body 32 integrally joined to the metal ring 31. Metal ring 31 is cylindrical part 33
And an inward flange portion 34 extending inward in the radial direction from the atmosphere-side end portion. The seal lip 5 extends from the inner diameter end portion of the inward flange portion 34 toward the fluid O to be sealed in the axial direction. The dust lip 11 has an inward flange portion 34.
From the end of the inner diameter toward the atmosphere side A in the axial direction so as to gradually decrease in diameter.

The inner peripheral shape of the lip tip portion 4 of the seal lip 5 has a mountain-shaped cross section projecting radially inward, and gradually decreases in diameter from the top portion 6 serving as a sliding surface toward the atmosphere side A in the axial direction. Air-side inclined surface 8 inclined in a conical shape as described above, and a sealing object fluid-side inclined surface 7 inclined in a conical shape so as to gradually decrease in diameter from the top portion 6 toward the axially sealed fluid side O.
And Further, a spring member 16 such as a garter spring is attached to the outer periphery of the lip tip 4 to apply a tightening force to the seal portion of the lip tip 4.

Atmospheric side inclined surface 8 on the inner periphery of lip tip 4
, A plurality of first and second boat bottom screw protrusions 9 and 10 as first and second screw protrusions are alternately formed at predetermined intervals along the circumferential direction. The first and second boat bottom screw projections 9 and 10 extend linearly from the fluid to be sealed toward the atmosphere, and intersect with the atmosphere-side inclined surface 8 and a plane passing through the central axis (atmospheric-side inclined surface 8). (Corresponding to the generatrix of the cone that constitutes).

As shown in FIG. 1D, the projection height of the first boat bottom screw projection 9 gradually increases from the fluid-side end 91 to the atmosphere toward the atmosphere, and the atmosphere-side end 92 rises. It is the maximum height. The cross-sectional shape orthogonal to the length direction of the first boat bottom screw protrusion 9 is triangular as shown in FIG. 1 (c), and its top forms a ridge line that is linearly continuous. Since the angle of the top is the same angle over the entire length of the ridge line, the width of the portion where the left-right inclined surface with respect to the ridge line intersects with the air-side inclined surface 8 of the lip tip 4 gradually increases from the sealing target fluid side end 91 toward the atmosphere side A. It becomes large and the bottom end 92 has a boat bottom shape with the maximum width.

The end 91 of the first screw thread 9 on the fluid side to be sealed is located at a predetermined distance from the top 6 of the lip tip 4 on the atmosphere side. A minute parallel screw protrusion 93 is provided between the side end portion 91 and the top portion 6 on an extension of the first boat bottom screw protrusion 9.
The width and height of the parallel screw protrusion 93 are formed to be the same in the length direction.

The second bottom screw projection 10 has exactly the same shape as the first bottom screw projection 9, and its direction is only reversed. That is, the projecting height of the second boat bottom screw protrusion 10 gradually increases from the air side end 12 toward the fluid to be sealed, and the fluid side end 11 has the maximum height.

The cross-sectional shape orthogonal to the length direction of the second boat bottom screw projection 10 is also triangular, and the width of the portion where the left and right inclined surfaces with respect to the ridge line intersect with the atmosphere-side inclined surface 8 of the lip tip portion 4 is the atmosphere-side. It gradually increases from the end 12 toward the fluid to be sealed, and has a bottom shape in which the fluid-side end 12 has the maximum width.

The end 11 on the fluid side to be sealed of the second boat bottom screw projection 10 is located substantially at the top 6 of the lip tip 4. Further, a minute parallel projection 13 extends by a predetermined length from the atmosphere side end portion 12 on an extension thereof.

If there is an initial air leak problem, not shown, as in the case of the parallel screw projection 93 located on the side of the first boat bottom screw projection 9 on the fluid to be sealed, the second boat bottom screw projection 10 is not shown. A parallel projection may be formed at a predetermined distance between the fluid-side end portion 11 and the top portion 6 to be sealed. In this manner, the displacement of the second boat bottom screw protrusion 10 at the fluid-side end 11 to be sealed can be absorbed by the parallel protrusion.

In the sealing device having the above-described structure, in the initial state and the initial stage of wear, the top 6 of the lip tip 4 is tightly contacted over the entire circumference to form a seal portion, and at the same time, the first boat bottom screw projection 9 is formed. The parallel screw protrusion 93 and the second boat bottom screw protrusion 10 following the tip come into contact with the sealed fluid side end portion 11 where the height is high, thereby exhibiting a screw pump function.

Parallel screw protrusion 93 and second boat bottom screw protrusion 1
As the wear of the fluid-side end portion 11 having a high height of 0 increases, the pumping action decreases, but the first bottom screw thread 9 comes into contact and the pumping action of the first bottom screw thread 9 starts to function. A reduction in the suction amount is prevented. Further, the air-side end 92 at which the first bottom screw protrusion 9 has the maximum height,
Since the parallel screw protrusions 13 continuous from the atmosphere side end 12 of the boat bottom screw protrusion 10 are arranged in the circumferential direction, the contact state becomes the same as the initial state, and a stable sealing performance can be obtained from the initial stage to after the wear progresses. .

In the above-described embodiment, the first and second boat bottom screw projections 9 and 10 are provided alternately. However, they may be provided every few or at random.

Further, the first and second screw protrusions are formed in a boat bottom shape in which the height is increased while gently curving the first and second screw protrusions.
Although the boat bottom screw projections 9 and 10 are used, they may be tapered screw projections having a tapered shape such that the height increases linearly.

In the above embodiment, the so-called inner seal in which the seal body 3 is fixed to the housing 1 and the seal lip 5 is in sealing contact with the rotary shaft 2 has been described. However, the seal body is fixed to the rotary shaft and the seal lip is fixed to the housing. Needless to say, the present invention can be applied to a so-called outer seal that comes into sealing contact with the inner periphery.

[0029]

As described above, according to the present invention, the protrusion height gradually increases from the end of the fluid to be sealed toward the atmosphere and the maximum height is located at the end of the atmosphere. By providing both a screw projection and a second screw projection whose projection height gradually increases from the atmosphere side end toward the sealed fluid side and whose maximum height is located at the sealed fluid side end. In the initial state and the initial stage of wear, the top of the tip of the lip is in close contact with the entire circumference, and at the same time, the end of the fluid to be sealed on which the height of the second screw protrusion is high contacts to exhibit the screw pump function, After the abrasion progresses, the portion where the height of the second screw protrusion is high wears and the pumping action of the second screw protrusion is reduced, but the first screw protrusion comes into contact with the first screw protrusion and the first screw protrusion contacts the first screw protrusion. The pumping function works, and pumping is performed over a wide range from the initial state to Suction amount is improved, stable sealing performance can be obtained.

Further, the degree of freedom in designing the screw projection is improved,
It is possible to control the pump amount.

[Brief description of the drawings]

FIG. 1 shows a sealing device according to an embodiment of the present invention. FIG. 1 (a) is a longitudinal sectional view of a sealing lip portion,
FIG. 2B is a longitudinal sectional view of a main part, FIG. 2C is an orthogonal sectional view of the first bottom screw protrusion of FIG. 2B, and FIG. 2D is the first boat of FIG. It is sectional drawing which follows the ridgeline of a bottom screw protrusion.

FIG. 2 shows a conventional sealing device.
(a) is a longitudinal sectional view of a seal lip portion, and (b) is a longitudinal sectional view of a main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Rotating shaft 3 Seal main body 4 Lip tip 5 Seal lip 6 Top 7 Sealed fluid side inclined surface 8 Atmospheric side inclined surface 9 First boat bottom screw projection (first screw projection) 91 Sealed fluid side end 92 Atmospheric end 93 Parallel screw protrusion 10 Second boat bottom screw protrusion (second screw protrusion) 11 Fluid end to be sealed 12 Atmospheric end 13 Parallel screw protrusion 14 Parallel screw protrusion 15 Dustrip O Sealable fluid Side A Atmospheric side

Claims (2)

[Claims] An annular gap between two members which are assembled concentrically and relatively rotatably with each other is sealed.
An annular seal body attached to one of the members,
A seal lip extending from the seal body to the fluid to be sealed and having a lip tip slidably and sealingly contacting the other of the two members, the lip tip having a mountain-shaped cross section, A sealing device having an atmosphere-side inclined surface inclined so as to gradually become smaller in diameter toward an axial direction atmosphere side, and a plurality of screw projections provided on the atmosphere-side inclined surface, wherein the screw projection has a sealing height. A first screw protrusion whose height is gradually increased from the target fluid side end toward the atmosphere side and whose maximum height is located at the atmosphere side end; A second screw protrusion that is gradually raised and whose maximum height is located at the end of the fluid to be sealed on the side thereof. 2. The sealing device according to claim 1, wherein the first screw protrusions and the second screw protrusions are arranged alternately or every several screws.