JPH11351406A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device with improved wear resistance so as to ensure a long lifetime and enhance the sealing property. SOLUTION: In a sealing device 1 with a seal lip 5 having two lip surfaces, each of which spreads mutually apart from the lip front edge portion abutting to the sliding surface, the seal lip 5 comprises a recessed portion 6 where one lip surface 51 is recessed by being spaced apart a predetermined distance (S) from the lip front edge portion of the lip surface 51 of either one of the two lip surface.

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.

[0002]

2. Description of the Related Art Conventionally, as this type of sealing device, there is, for example, one shown in FIGS. 4 (a) and 4 (b). That is, the sealing device 100 is a housing 101 as two members that are concentrically and relatively rotatably assembled with each other.
And a circular gap between the rotary shaft 102 inserted into the housing 101 and the rotary shaft 102.

[0003] The sealing device 100 includes a housing 101.
And a seal lip 104 made of, for example, a rubber-like elastic body, which slidably and sealingly contacts the outer peripheral surface of the rotating shaft 102. Further, a spring 105 for applying a tightening force is mounted on the outer periphery of the seal lip 104.

[0004] As shown in FIG.
It is known that the contact pressure distribution of the seal lip 104, when used in contact with the rotary shaft 102, is more effective when the peak is provided on the sealed fluid side O.

Accordingly, in order to provide the peak of the contact pressure distribution of the seal lip 104 on the sealed fluid side O, the contact angle of the atmosphere side A as the anti-sealed fluid side of the seal lip 104 is α, and the contact angle of the sealed fluid side O is α. Is set to β, α <β.

[0006]

However, in the case of the prior art described above, when the wear of the seal lip 104 progresses, the sealing fluid side O having a high contact pressure is liable to wear,
The wear width from the sealed fluid side O to the atmosphere side A formed by wear increases, and the seal lip 1
04, the contact angle α increases and the contact angle β decreases, the peak of the contact pressure distribution of the seal lip 104 moves to the atmosphere side A, the sealing performance deteriorates, and the sealing fluid leaks. There was a problem that it became easier.

Further, when the seal lip 104 wears unevenly due to shaft eccentricity, the contact pressure against the rotating shaft 102 is not uniform on the outer periphery of the rotating shaft 102, and a high portion and a low portion are generated. There is a problem that the sealing fluid leaks from a portion where the pressure is low.

Further, if the contact angle α is set too small in order to maintain the contact angles α and β at α <β, if the seal lip 104 contacts the rotary shaft 102 from the sealed fluid side O to the atmosphere side A, The width is increased and excessive wear occurs, shortening the life of the device. Similarly, if the contact angle β is set too large, the seal lip 104 is easily turned up or damaged when the rotating shaft 102 is inserted, and leakage is likely to occur at the beginning of use.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to improve the wear resistance and extend the life and to improve the sealing performance. Is to provide.

[0010]

According to the present invention, there is provided a sealing device having a sealing lip having two lip surfaces which spread apart from each other at a distance from a lip tip abutting on a sliding surface. Wherein the seal lip is provided with a concave portion in which one of the two lip surfaces is recessed at a predetermined distance from a lip tip of one of the two lip surfaces.

As a result, the portion of the seal lip provided with the concave portion becomes thinner, so that even when the wear of the seal lip progresses, the wear width from the sealed fluid side formed by abrasion to the anti-sealed fluid side is formed. Expansion is suppressed.

Therefore, the seal lip can be maintained longer in the state close to the initial stage of use, the service life can be prolonged, and the thinner wall thickness increases the elasticity of the seal lip, so that the seal lip can follow the eccentricity. To prevent uneven wear, the contact pressure on one member becomes uniform on the circumference,
Improves sealing performance.

Preferably, the one lip surface is a sealing fluid side lip surface.

[0014] This makes it possible to provide a large contact angle from the surface of the seal lip provided with the concave portion to the sliding surface on the side of the sealing fluid to the sliding surface, thereby increasing the contact pressure distribution of the seal lip for a longer period of time. By maintaining the distribution peak on the sealed fluid side, the service life can be extended.

It is preferable that the seal lip has the two lip surfaces which extend to each other across the vertical direction of the sliding surface.

Accordingly, the thickness of the portion of the seal lip provided with the concave portion is reduced, so that the wear width is suppressed from being increased, and the seal lip can be maintained longer in the state close to the initial stage of use, and the service life can be extended.

[0017] It is preferable that a biasing means for pressing a lip tip of the seal lip against a sliding surface is provided.

As a result, the sealing lip obtains a tightening force and is released by the concave portion to relieve the tightening force, so that the speed at which the seal lip is worn can be suppressed, thereby also extending the life.

[0019]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

FIG. 1 shows a sealing device according to an embodiment.
In FIG. 1A, a sealing device 1 seals an annular gap between a housing 2 as two members which are assembled concentrically and relatively rotatably and a rotating shaft 3 inserted into the housing 2.

The sealing device 1 is provided with a fitting portion 4 assembled on the inner periphery of the housing 2 and a seal lip 5 slidably sealingly contacting the outer peripheral surface of the rotating shaft 3.

The fitting portion 4 is composed of a reinforcing ring 7 and a rubber-like elastic body 8, and the reinforcing ring 7 is a cylindrical member having an inward flange 71 extending radially inward. The rubber-like elastic body 8 is integrally fixed to the end face of the atmosphere side A as the anti-sealing fluid side of the inward flange portion 71 of the reinforcing ring 7, the outer peripheral face of the cylindrical portion 72, and the end face of the sealing fluid side O continuously. ing.

The fitting portion 4 is provided on the cylindrical portion 7 of the reinforcing ring 7.
2 is attached to the inner peripheral surface of the housing 2 via a rubber-like elastic body 8.

The inward flange 71 of the reinforcing ring 7
A seal lip 5 and a dust lip 9 made of a rubber-like elastic material are provided at an inner end of the lip.

The seal lip 5 has an inward flange 71
From the inner end to the sealing fluid side O
And a lip tip portion slidably and sealingly contacts an outer peripheral surface as a sliding surface of the rotating shaft 3, and has a wedge-shaped cross-section having two lip surfaces that spread apart from each other as the distance from the lip tip portion increases. .

In order to provide the peak of the contact pressure distribution of the seal lip 5 on the sealed fluid side O, the seal lip 5
When the contact angle on the atmosphere side A is α and the contact angle on the sealed fluid side O is β, α <β is set to seal the lip tip that receives the most tightening force from the vertical line with respect to the sliding surface. Fluid side O
The contact distance was reduced.

On the outer periphery of the seal lip 5, a spring 10 as urging means for applying a tightening force to the outer peripheral surface of the rotary shaft 3 is mounted all around.

As the urging means, not only the spring 10 but also the elasticity of the seal lip 5 itself may be used, but it is not limited to these.

The dust lip 9 extends from the inner end of the inward flange portion 71 of the reinforcing ring 7 to the atmosphere side A, and has a plate-like cross section inclined toward the rotating shaft 3. The outer peripheral surface 3 is slidably and sealingly contacted with the outer peripheral surface. This prevents dust from entering from the atmosphere side A.

As shown in an enlarged view in FIG. 1B, a concave portion 6 is provided on the entire circumference of the sealing fluid side O lip surface 51 of the seal lip 5, and the concave portion 6 The lip surface 51 is recessed into the lip surface from a position separated by a predetermined distance S from the lip tip.

The predetermined distance S at which the position where the concave portion 6 is provided is separated from the tip of the lip is preferably in the range of 0.1 to 2.0 mm.

This is because when the recess 6 is too close to the lip tip, the sealing fluid side O lip surface 51 of the sealing lip 5
From the beginning to the outer peripheral surface of the rotating shaft 3, the contact angle β is too large, and when the rotating shaft 3 is inserted, the seal lip 5 is easily turned over or damaged, easily leaking at the beginning of use, and When the concave portion 6 is provided at a distance larger than 2.0 mm from the tip of the lip, the seal lip 5 is worn before the effect of the provision of the concave portion 6 is exerted, which is the same problem as the related art. Is caused. To prevent this, the predetermined distance S from the tip of the lip is provided in the range of 0.1 to 2.0 mm.

Further, as the seal lip 5 wears the seal lip 104, as the seal lip 104 wears, the sealing fluid side O having a high contact pressure is liable to be worn, and the sealing lip 5 formed from the abraded seal fluid side O to the atmosphere side. The wear width up to A is formed in the order of a, b, and c.

In the present invention, when the abrasion width formed by the abrasion of the seal lip 5 is applied to the recess 6 due to the abrasion, the recess 6 is provided as shown in states b and c. Because the thickness of the seal lip 5 itself is thin,
The expansion of the wear width is suppressed (see FIG. 2A).
As the wear progresses as in the prior art, the contact angle β from the sealing fluid side O lip surface 51 to the outer peripheral surface of the rotating shaft 3 decreases, but the recess 6 recesses the sealing fluid side O lip surface 51 to make contact. Since the angle β is increased, the speed at which the contact angle β decreases is suppressed (see FIG. 2B).

As a result, the contact angle β becomes smaller, and the speed at which the peak of the contact pressure distribution of the seal lip 5 moves to the atmosphere side A can be suppressed. By maintaining the state provided on the fluid side O, the life can be extended.

The tension is applied by a spring 10 mounted on the entire outer periphery of the seal ring 5, but the tension is released and relieved by the recess 6, and the seal lip 5 is released.
The speed at which the surface is worn down is suppressed, thereby also extending the life.

Further, with respect to the axial eccentricity of the rotating shaft 3, the followability of the seal lip 5 is improved by increasing the thickness of the seal lip 5 at the portion where the concave portion 6 is provided and increasing the elasticity. Wear is prevented, the contact pressure on the rotating shaft 3 becomes uniform on the circumference, and the sealing performance is improved.

The present invention can be applied to not only the sealing device having the structure of the present embodiment but also a device provided with a seal lip. Further, the concave portion provided in the seal lip is not limited to the present embodiment. Instead, as shown in FIG. 3, the sealing fluid side O may be a concave portion 6 ′ in which the sealing fluid side O is dented as it is from a position separated from the lip tip by a predetermined distance S, and thus a position separated from the lip tip by a predetermined distance S. The present invention is not limited thereto, and the present invention can be applied as long as a concave portion is provided on the inner side of the lip.

[0039]

According to the present invention, the seal lip is provided with a concave portion in which one of the two lip surfaces is recessed at a predetermined distance from the lip tip of one of the lip surfaces. Since the thickness of the portion of the seal lip provided with the concave portion becomes thinner, even if the wear of the seal lip progresses, an increase in the wear width from the sealed fluid side formed by abrasion to the anti-sealed fluid side is suppressed. The seal lip is maintained longer in the state close to the initial stage of use, the service life can be extended, and the thinner wall thickness increases the elasticity of the seal lip and improves the followability of the seal lip against eccentricity, Uneven wear is prevented, the contact pressure on one member becomes uniform on the periphery, and the sealing performance is improved.

Since the one lip surface is the sealing fluid side lip surface, a large contact angle from the sealing fluid side surface to the sliding surface of the portion provided with the concave portion of the sealing lip can be provided. The contact pressure distribution is maintained longer with the peak of the contact pressure distribution closer to the initial stage of use provided on the sealed fluid side, and the life can be extended.

The seal lip is provided with two lip surfaces that extend mutually across the vertical direction of the sliding surface, so that the thickness of the portion of the seal lip provided with the concave portion is reduced, thereby preventing the wear width from increasing. The seal lip is maintained longer in the state close to the initial stage of use, and the service life can be extended.

The provision of the urging means for pressing the lip tip of the seal lip against the sliding surface provides the sealing lip with a tightening force, and the concave portion releases the tightening force to relieve the sealing lip. Speed can be suppressed, thereby also extending the life.

[Brief description of the drawings]

FIG. 1A is a sectional view showing a sealing device according to an embodiment, and FIG. 1B is an enlarged view showing a sealing lip.

FIG. 2A is a graph showing a relationship between a wear width and time, and FIG. 2B is a graph showing a relationship between a contact angle β and time.

FIG. 3A is an enlarged view showing another example of a seal lip according to the embodiment.

4 (a) is a sectional view showing a conventional sealing device, FIG. 4 (b) is an enlarged view showing a seal lip, and FIG. 4 (c) shows a contact pressure distribution of the seal lip. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing device 2 Housing 3 Rotating shaft 4 Fitting part 5 Seal lip 51 Sealing fluid side O contact surface 6, 6 'Concave part 7 Reinforcement ring 71 Inward flange part 72 Cylindrical part 9 Dust lip 10 Spring

Claims (4)

[Claims] 1. A sealing device comprising a sealing lip having two lip surfaces that extend away from each other from a lip tip abutting a sliding surface, wherein the sealing lip is one of two lip surfaces. A predetermined distance away from the front lip tip,
A sealing device comprising a concave portion in which said one lip surface is depressed. 2. The sealing device according to claim 1, wherein the one lip surface is a sealing fluid side lip surface. 3. The sealing device according to claim 1, wherein the sealing lip includes the two lip surfaces that extend from each other across a vertical direction of a sliding surface. 4. The sealing device according to claim 1, further comprising a biasing means for pressing a lip tip of the seal lip against a sliding surface.