JP2000346202A - Sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate oil leakage caused by the squeezing of seal and to prevent a sliding part from insufficient lubrication, increasing the friction and abnormal wear. SOLUTION: This sealing structure is provided with a sliding member 2, a supporting member 1 for slidably supporting the sliding member 2, and a seal ring 5a interposed between the sliding member 2 and the supporting member 1. In this case, the seal ring 5a is accommodated in a housing recessed part 25, with a prescribed gap, while an elastic member 5b allowing the seal ring 5a to deform toward the outer periphery absorbing the effect of the deformation is arranged within the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a seal structure of a hydraulic cylinder or the like.

[0002]

2. Description of the Related Art Conventionally, as a seal structure of a bearing portion such as a hydraulic cylinder, there is one disclosed in Japanese Utility Model Laid-Open No. 4-138160. This is because the fitting groove of the seal ring is parallel to the inner and outer diameters, and the pressure receiving area in the axial direction of the seal ring is the entire inner and outer lip diameters, so that the support area of the heel portion is substantially the same as the pressure receiving area.

[0003] When high pressure acts on the lip portion, the surface pressure of the heel portion increases in response to the high pressure, and the deformation of the heel portion protrudes and the surface pressure gradient on the sliding surface is large. There is a problem that oil leakage due to scraping occurs depending on the operating conditions.

Further, as the pressure increases, the scraping property of the hydraulic oil film becomes stronger, so that the sliding portion becomes non-lubricated, friction increases, and frictional heat is generated.
During continuous operation for a long time, it causes thermal deterioration of the sliding part,
The problem of abnormal wear is also conceivable.

Japanese Patent Application Publication No. 9-504081 discloses a technique relating to a specially shaped seal having a gap on the inner and outer circumferences of a seal ring having a gap on the back surface.

[0006] This is considered to pursue a specially shaped ring in order to prevent the protrusion from protruding into the heel portion due to pressure, to make the gap between the inner and outer diameters as large as possible (up to the allowable limit of the deformation stress of the material), and to pursue a specially shaped ring. When a large volume gap is provided by a tapered surface, there is a limit to the applied pressure due to deformation stress, and especially high stress is concentrated on the inner diameter of the heel, and from the viewpoint of durability fatigue performance, the application conditions are limited. Conceivable.

Further, in the configuration in which the buffer ring and the seal ring described in Japanese Patent Publication No. 6-100202 are combined, the buffer ring does not have a completely closed structure in order to secure a hydraulic oil film. In any case of operation, in the flow regeneration circuit in which the rod side oil chamber becomes high pressure, the pressure between the seal ring and the buffer ring is accumulated, and when the load pressure is operated for a long time, the high pressure action on the seal ring Cannot be prevented.

An object of the present invention is to provide a seal structure which solves these problems.

[0009]

According to a first aspect of the present invention, there is provided a sliding member, a supporting member for slidably supporting the sliding member, and a seal ring interposed between the sliding member and the supporting member. In the seal structure having the above, the seal ring is housed in a storage recess provided in the support member with a predetermined gap, and an elastic member that allows deformation and absorbs to the outer periphery of the seal ring is disposed in the gap. I do.

According to a second aspect, in the first aspect, a gap is provided between at least one of the elastic member and the seal ring or between the elastic member and the support member.

[0011] In a third aspect based on the first aspect, the elastic member is accommodated in the gap without any gap.

[0012]

According to the first to third aspects of the present invention, the seal ring is composed of the main body and the elastic member provided on the outer periphery thereof.
By taking into account the clearance volume and the like, it is possible to allow deformation to the outer peripheral side in proportion to the pressure acting on the lip side, and to absorb this, making it possible to make the change in the inner diameter dimension almost zero. it can. Therefore, contact and biting with the piston rod are prevented, and problems such as increased friction and oil leakage are eliminated.

Further, since the elastic member is a separate component from the seal ring, it is possible to freely change the shape and the material and freely control the deformation of the seal ring.

Further, by dividing into a seal ring and an elastic member, the shape of each part can be simplified, and improvement in die cost and work efficiency can be expected.

By suppressing the change in the inner diameter of the seal ring to a small value, the stress generated at the inner diameter can be reduced, the fatigue strength of the seal is improved, and the durability is improved.

Further, by providing predetermined gaps on the inner and outer peripheral sides of the elastic member, the deformation of the seal ring can be controlled in accordance with the elastic characteristics of the elastic member.

[0017]

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

As shown in FIGS. 1 and 2, the hydraulic cylinder 2
0 of the piston rod 2 is in the sliding hole 21 of the cylinder head 1.
Are slidably penetrated, and a bearing portion 30 is formed in this penetrating portion. The bearing 4 includes a bearing 4 and a seal ring 5.
Are arranged, and furthermore, the dust seal 9
Is provided. The bearing 4 and the dust seal 9 each have the groove 2
4 and 29, and the seal ring 5 is housed in a storage recess 25 formed in the slide hole 21.

The seal ring 5 includes a seal ring main body 5a and a control ring 5b for controlling deformation of the seal ring main body 5a provided on the outer peripheral portion of the seal ring main body 5a.
And is mounted in a storage recess 25 that opens directly into the rod-side oil chamber 3 of the hydraulic cylinder 20. The seal ring main body 5a has a lip portion 10 that directly receives the pressure of the hydraulic oil, and an inner and outer diameter that is substantially the same as the lip portion 10, and applies the pressure acting on the lip portion 10 to the housing recess 2 of the cylinder head 1.
And a heel portion 11 for receiving the heel portion 5.

On the other hand, the control ring 5b is mounted on the outer peripheral side of the seal ring main body 5a, and is disposed in the storage recess 25. The control ring 5b is selected from shapes and materials corresponding to the deformation of the seal ring 5 so as to allow and absorb the deformation of the seal ring 5 to the outer peripheral side.

Further, the lip portion 1 of the seal ring body 5a
0 comprises an inner lip 10a and an outer lip 10b,
The heel portion 11 is the heel portion 1 of the seal ring main body 5a.
1x and the heel 11y of the control ring 5b.

The heel 11y of the control ring 5b forms a support surface 11a with the heel 11x of the seal ring main body 5a, and supports the seal ring 5.

The recess 25 of the cylinder head 1 for accommodating the seal ring 5 also has a groove cross section basically corresponding to the outer shape of the seal ring 5, and a rod shaft center contacting the outer periphery of the outer lip 10 b of the lip portion 10. The lip bottom wall 25a is parallel to the lip, the inclined wall 25b is in contact with the inclined outer peripheral surface of the control ring 5b, the heel wall 25c is orthogonal to the rod axis which is in contact with the support surface 11a of the heel 11, and the outer peripheral 11y of the heel 11 is predetermined. Of the heel bottom wall 25d that defines the gap 40, so that the oil pressure acting on the lip portion 10 does not directly act on the heel portion 11 (that is, the operating oil does not leak to the heel portion 11). The outer periphery of the outer peripheral lip 10b of the lip portion 10 has a fixed interference with the inner surface of the lip bottom wall 25a of the storage recess 25, and the inner peripheral lip 10a has a fixed interference with the outer periphery of the piston 2. It is adapted to wear.

In other words, the pressure receiving area Am of the lip portion 10
Is an annular area between the outer circumference of the lip 10 when the seal ring is assembled and the inner circumference that slides on the piston rod 2,
On the other hand, the annular area between the outer periphery and the inner periphery of the heel portion 11 is the support area As of the entire heel portion, and the relationship between them is Am <As.

Note that, as shown in FIG.
Is in the free state, the lip 10a on the inner peripheral side of the lip portion 10
Are formed on the inner diameter side so as to come into contact with the piston rod 2 at a predetermined pressure and are reduced by the interference, and the outer peripheral lip 10 on the outer peripheral side is formed.
The outer circumference of b is formed by expanding the outer diameter side by the amount of the interference, and is in close contact with the storage recess 25 on the inner surface.

The lip bottom wall 25a of the storage recess 25 communicates directly with the rod-side oil chamber 3 via the communication hole 15.
The lip bottom wall 25a and the communication hole 15 have substantially the same diameter.

The configuration is as described above. Next, the operation will be described.

The conventional one shown in FIG.
Of the seal ring 5 is parallel to both the inner and outer diameters.
0, the pressure receiving area Ap of the lip portion 55 is large, and the heel portion 5
6 is almost the same as the support area As. Therefore, the thrust caused by the pressure acting on the lip portion 55 increases,
The surface pressure of the heel portion 56 also increases. Therefore, the heel portion 56
Although it is crushed and tries to deform, the outer diameter side is restrained by the cylinder head 1 and the deformation concentrates on the piston rod 2 side. Thereby, the heel part 5
Part 6 strongly contacts the piston rod 2 and causes problems such as increased friction. Therefore, conventionally,
In order to prevent this problem, buffering has been used to limit the pressure acting on the seal ring 5.

On the other hand, in the present invention, as shown in FIG. 5, the supporting area As of the heel portion 11 is made larger than the pressure receiving area Am of the lip portion 10, so that the thrust acting on the seal ring 5 is suppressed, 11 can be reduced. Thereby, the deformation of the seal ring 5 can be reduced, and the heel corner 11x of the heel 11
Can be prevented from protruding toward the piston rod 2 as much as possible.

Further, the seal ring 5 includes a seal ring main body 5a having a lip portion 10 having a sealing function and a control ring 5b for absorbing and controlling deformation of the seal ring main body 5a to the outside.

With such a configuration, the lip portion 10
It has been clarified by analysis by the inventors that the seal ring main body 5a can substantially prevent deformation in the inner diameter direction when pressure acts on the seal ring main body 5a.

That is, the inventors regard the deformation of the seal ring as the deformation of the annular columnar body, support the lower surface, and create an annular cylindrical model in which a constant distributed load is applied to the upper surface.
An analysis was performed to confirm the deformation of the model by changing the support conditions of the inner and outer circumferences.

As a result, it was found that when the inner and outer peripheries are in the free state, the diameter of the model is increased in both the inner and outer peripheries.

From these results, it is understood from the results that the control ring 5 for suppressing the outward deformation of the seal ring main body 5a as in the present invention.
It was confirmed that by providing b on the outer periphery of the seal ring main body 5a and controlling the expansion of the outer diameter of the seal ring main body 5a, the deformation of the inner diameter can be reduced to zero.

For this reason, the deformation of the outer peripheral portion of the seal ring main body 5a is proportional to the applied pressure by considering the shape, material characteristics, volume, etc. of the control ring 5b while maintaining the effect of the seal ring. As a result, the change in the inner diameter dimension can be made substantially zero.

Accordingly, contact with the piston rod 2 and biting are prevented, and problems such as increased friction and oil leakage are eliminated.

Further, since the control ring 5b is a separate part from the seal ring main body 5a, the deformation of the seal ring 5 can be freely controlled by freely changing its shape and material.

The seal ring body 5a and the control ring 5
By dividing the seal ring 5 into b, the shape of each part can be simplified, and improvement in die cost and work efficiency can be expected.

Since the change in the inner diameter of the seal ring 5 can be made smaller, the stress generated in the inner diameter can be reduced, the fatigue strength of the seal is improved, and the durability is improved.

It is extremely effective to change the groove shape of the storage recess 25 in which the seal ring 5 is mounted in order to control the deformation of the seal ring.
Even after the shape is determined, cutting can be performed in accordance with the deformation, and the deformation of the seal ring 5 can be more accurately controlled.

FIG. 6 shows a second embodiment in which gaps 40 and 41 are provided between a part of the joint surface between the control ring 5b and the seal ring main body 5a and the control ring 5b and the storage recess 25, respectively. It is a thing. The support surface 11b for supporting the heel portion 11y of the control ring 5b is formed not at the same plane as the support surface 11a of the heel portion 11x of the seal ring body 5a but at a different angle.

By arranging the gaps 40 and 41 and the control ring 5b in this way, it is the same as arranging springs having different spring constants in the radial direction of the seal ring 5 in series.
The degree of freedom of the spring system for controlling the deformation of the seal ring main body 5a can be increased.

FIG. 7 shows a third embodiment. This is because the control ring 5b, the seal ring body 5a and the storage recess 2
5 is not provided. With such a configuration, the deformation of the seal ring can be absorbed and controlled.

FIG. 8 shows a fourth embodiment. This is because the control ring 5b is provided with holes 4 radially from the axial center of the seal ring 5.
2, the elastic properties of the control ring 5b are optimally determined by the size and distribution density of the holes 42 to absorb the deformation of the seal ring main body 5a.

In this embodiment, the shape of the seal ring 5 has been described as a seal shape in which the pressure receiving area of the lip portion and the support area of the heel portion are different, but the shape is not limited to this shape.

That is, the present invention is also applicable to a conventional seal structure having substantially the same pressure receiving area and supporting area. This case will be described below.

FIG. 9 shows a fifth embodiment. This is because the outer diameter of the lip 10 of the seal ring body 5a is
x, which is larger than the outer diameter of x. By doing so, a gap is created between the heel portion 11x and the storage recess 25, and the deformation of the seal ring 5 is guided in a direction to increase the diameter, and the deformation is applied to the gap. The control is performed by a control ring 5b formed by stacking, for example, materials having different material characteristics in layers.

By disposing the control ring 5b in the gap, the shape of the seal ring 5 becomes an annular columnar body, and the processing of the storage recess 25 can be facilitated.

Further, by using the control ring 5b formed by laminating materials having different material characteristics in layers, the degree of freedom in selecting material characteristics can be increased.

FIG. 10 shows a sixth embodiment. In this case, the control ring 5b is provided so that there is no gap between the seal ring main body 5a and the storage recess 25.

FIG. 11 shows a seventh embodiment. This is because the control ring 5b, the seal ring body 5a and
A gap 43 is provided at a part of each of the boundaries with the reference numeral 5.

FIG. 12 shows an eighth embodiment. This is because a gap 44 is formed at a part of the boundary between the control ring 5b and the seal ring main body 5a, and a gap 45 is formed over the entire periphery of the boundary with the storage recess 25.
Is provided.

FIG. 13 shows a ninth embodiment. This is provided with a gap 46 at a part of the boundary between the control ring 5b and the seal ring main body 5a.

FIG. 14 shows a tenth embodiment. This is one in which a gap 47 is provided all around the boundary between the control ring 5b and the seal ring main body 5a.

FIG. 15 shows an eleventh embodiment. In this method, a step portion having a different diameter is provided on the outer peripheral portion of the seal ring main body 5a, and a control ring 5b is formed along the step portion. And a gap 49 is provided over the entire periphery of the boundary between the control ring 5b and the storage recess 25.

According to the sixth to eleventh embodiments, it is possible to cope with the deformation mode and the deformation amount of the seal ring main body 5a.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a detailed shape of the seal ring.

FIG. 3 is a sectional view showing a free shape of the seal ring.

FIG. 4 is a schematic diagram showing working pressure and deformation in a conventional seal ring shape.

FIG. 5 is a schematic diagram showing the working pressure and deformation of the seal ring in the first embodiment.

FIG. 6 is an essential part cross-sectional view showing the shape of the second embodiment.

FIG. 7 is an essential part cross-sectional view showing the shape of the third embodiment.

FIG. 8 is an essential part cross-sectional view showing the shape of the fourth embodiment.

FIG. 9 is an essential part cross-sectional view showing the shape of the fifth embodiment.

FIG. 10 is an essential part cross-sectional view showing the shape of the sixth embodiment.

FIG. 11 is a sectional view of an essential part showing a shape according to a seventh embodiment;

FIG. 12 is an essential part cross-sectional view showing the shape of the eighth embodiment.

FIG. 13 is an essential part cross-sectional view showing the shape of the ninth embodiment.

FIG. 14 is an essential part cross-sectional view showing the shape of the tenth embodiment.

FIG. 15 is an essential part cross-sectional view showing the shape of the eleventh embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Piston rod 4 Bearing 5 Seal ring 10 Lip part 11 Heel part 40 Clearance

Continued on the front page (72) Inventor Koji Mitsushima F-term (reference) in the World Trade Center Building Kayaba Industry Co., Ltd. 2-4-1 Hamamatsucho, Minato-ku, Tokyo 3J043 AA13 BA08 CA02 CA06 DA02

Claims (3)

[Claims] 1. A sealing structure comprising a sliding member, a supporting member slidably supporting the sliding member, and a seal ring interposed between the sliding member and the supporting member. The seal structure wherein the ring is accommodated in a storage recess provided in the support member with a predetermined gap, and an elastic member is arranged in the gap to allow and absorb deformation of the seal ring to the outer peripheral side. . 2. The method according to claim 1, further comprising:
The seal structure according to claim 1, wherein a gap is provided in at least one of the elastic member and the support member. 3. The seal structure according to claim 1, wherein the elastic member is housed in the gap without any gap.