JP2000240806A - Sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oil leakage due to scraping and avoid abnormal wear due to friction increased in a non-lubricated sliding part. SOLUTION: Pressure applied to a ring seal is reduced to avoid deformation to the sliding surface side of a heel part 11, by making a pressure-applied area of a lip part 10 smaller than a supporting area of the heel part 11. This sealing structure is provided with a sliding member 2, a supporting member 1 where the sliding member 2 is slidably mounted, and a seal ring interposed between the sliding member 2 and the supporting member 1. This seal ring is formed with the lip part 10, to which pressure of a hydraulic oil is applied and the heel part 11 which supports the actuating pressure. A ring-shaped pressure receiving area between inner and outer peripheries of the lip part 10 is smaller than a ring-shaped supporting area between inner and outer peripheries of the heel part 11.

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.

[0002]

2. Description of the Related Art Conventionally, as a seal structure of a bearing portion of a hydraulic cylinder or the like, a backup ring is mounted to prevent the heel portion of the seal ring from protruding as described in Japanese Utility Model Laid-Open No. 4-138160. Things and Tokuhei 6
There is an apparatus in which an unload valve (buffering) is provided in order to reduce the pressure acting on the seal ring described in -100202.

However, in such a conventional seal structure, for example, in Japanese Unexamined Utility Model Publication No. 4-138160, the fitting groove of the seal ring is parallel to the inner and outer diameters, and the seal ring is disposed in the axial direction. Is the entire inner and outer lip diameters, so that the support area of the heel portion is almost the same as the pressure receiving area.

[0004] For this reason, at high pressure, the surface pressure of the heel portion is increased, and the heel portion is deformed to the sliding surface and the surface pressure gradient with respect to the sliding surface is large, so that the hydraulic oil film has a large scraping property and oil leakage due to the scraping occurs. There was a problem.

[0005] Further, the higher the pressure, the stronger the scraping property of the hydraulic oil film, so that the sliding part becomes non-lubricated, friction increases, and further, frictional heat is generated, and There is a problem of causing thermal deterioration and abnormal wear.

In the configuration described in Japanese Patent Publication No. 6-100202, in which a buffer ring and a seal ring are combined, the buffer ring is not completely sealed 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 The problem that cannot be prevented is considered.

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

[0008]

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, the seal ring is housed in a storage recess, and a lip portion on which hydraulic oil pressure acts, and a heel portion for supporting pressure acting on the seal ring on a side wall surface of the storage recess. The annular pressure receiving area between the inner circumference and the outer circumference of the lip portion is smaller than the annular support area between the inner circumference and the outer circumference of the heel portion.

In a second aspect based on the first aspect, the seal ring is interposed in a support member.

[0010] In a third aspect based on the first aspect, the seal ring is interposed in a sliding member.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the heel portion of the seal ring has a tapered surface separated from the lip portion in a direction opposite to the sliding surface of the seal ring. The configuration was adopted.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a heel portion of the seal ring and a holding member for holding the heel portion are interposed in the storage recess, and a contact surface of these heel portions is provided. When the pressure of the hydraulic oil is not acting therebetween, a gap is provided which becomes larger in the direction opposite to the sliding contact surface of the heel portion.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a tapered surface is formed on an outer periphery of an intermediate portion connecting the lip portion and the heel portion of the seal ring. A seal structure according to any one of claims 1 to 5, characterized in that:

According to a seventh aspect, in the sixth aspect, the hydraulic oil drain groove for guiding hydraulic oil to the heel portion between the tapered surface of the intermediate portion and the inner peripheral portion of the storage recess in which the seal ring is interposed is provided. 7. The seal structure according to claim 6, wherein the seal structure is provided.

[0015]

According to the first to third aspects of the present invention, when the operating oil pressure acts on the lip, the pressure receiving area of the lip is made smaller than the support area of the heel, so that the seal ring is deformed. Thrust is reduced. In addition, since the support area of the heel is larger than the pressure receiving area of the lip, the surface pressure generated in the heel is reduced. For this reason, it is possible to prevent the heel portion from protruding to the sliding surface, and it is possible to improve the durability reliability against oil leakage. Further, since the surface pressure of the heel portion can be reduced at a constant rate, contact of the heel portion with the sliding surface during high pressure operation can be suppressed, and friction can be reduced. Further, since the surface pressure of the heel portion is reduced, the working limit pressure of the seal ring can be further increased, and a pressure reducing mechanism such as a buffering can be eliminated. Therefore, the size of the seal in the sliding direction is reduced, and the entire seal structure can be downsized.

Since the shape of the seal ring is not symmetrical, it is possible to expect an effect that it is possible to prevent erroneous assembling at the time of assembling the seal ring, and to ensure the sealing performance.

According to the fourth aspect of the present invention, the heel portion of the seal ring is formed by a tapered surface which is separated from the lip portion in a direction opposite to the sliding surface of the seal ring. Release to the bottom direction, further equalize the surface pressure distribution on the support surface, protrude the heel to the sliding surface,
Biting can be prevented.

In the fifth invention, when the heel portion of the seal ring and the holding member for holding the heel portion are interposed in the storage recess, when the pressure of the hydraulic oil is not acting between these contact surfaces. Since a gap is provided which becomes larger in the direction opposite to the sliding contact surface of the heel portion, the deformation of the seal surely goes in the direction opposite to the sliding surface, and the deformation toward the sliding member side is suppressed.
The surface pressure and the surface pressure gradient on the sliding member are hardly affected by the operating pressure, and it is possible to realize an extremely stable sealing function.

According to the sixth aspect of the present invention, the taper surface is formed at an intermediate portion connecting the lip portion and the heel portion of the seal ring. Therefore, the pressure of the lip portion is directly applied to the support surface of the heel portion. The pressure distribution is also dispersed along the tapered surface without acting on the heel portion, and the heel portion can have a more uniform pressure distribution over the entire support surface of the heel portion.

In the seventh aspect of the present invention, the hydraulic oil drain groove for guiding the hydraulic oil to the heel side between the tapered surface and the inner peripheral portion of the storage recess in which the seal ring is interposed is provided, so that it acts on the lip portion. Even if high pressure leaks to the tapered surface, it can be discharged to the heel side of the atmospheric pressure using the hydraulic oil release groove, preventing the tapered surface from being added to the pressure receiving area of the lip where high pressure acts. it can.

[0021]

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

As shown in FIGS. 1 to 3, the piston rod 2 of the hydraulic cylinder 20
1 is slidably penetrated, and a bearing portion 30 is formed in this penetrating portion. The bearing portion 30 includes a bearing 4 and a seal ring 5.
Are arranged, and furthermore, the dust seal 8
Is provided. The seal ring 5 is housed in an annular groove 25 formed in the sliding hole 21.

The seal ring 5 is provided with a hydraulic cylinder 20
A lip portion 10 for directly receiving the pressure of the operating oil in the rod-side oil chamber 35, a heel portion 11 for receiving the pressure acting on the lip portion 10 in the annular groove 25 of the cylinder head 1, a lip portion 10 and a heel portion It is composed of an intermediate part 12 connecting the parts 11. The lip portion 10 is roughly divided into an inner lip 10a and an outer lip 10b.
Is formed smaller than the outer diameter of the heel portion 11, and the outer diameter of the intermediate portion 12 is formed by a tapered surface 12a that gradually increases from the lip portion side toward the heel portion side.

The annular groove 25 of the cylinder head 1 for accommodating the seal ring 5 also has a groove cross section corresponding to the outer shape of the seal ring 5, and the outer peripheral lip 10 of the lip portion 10.
b, the lip bottom wall 25a contacting the outer periphery of the intermediate portion 12, the inclined wall portion 25b contacting the outer peripheral taper surface 12a, and the heel portion 1
Heel wall 25c, lip 1 in contact with support surface 11a
0 and the wall of the lip vertical wall 25d which receives the pressure of the hydraulic oil so that the pressure acting on the lip 10 does not directly act on the heel 11 and the intermediate part 12 (that is, the hydraulic oil is The outer periphery of the fitting lip 10b of the lip portion 10 is in close contact with the inner surface of the lip bottom wall 25a of the annular groove 25 with a certain interference.

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 circumference and the inner circumference of the heel portion 11 is the support area As of the heel portion 11, and the relationship between them is Am <As.

As shown in FIG. 3, when the seal ring 5 is in the free state, the lip 10
a is formed by reducing the inner diameter side by the interference so that the piston lip contacts the piston rod 2 at a predetermined pressure.
The outer periphery of Ob is formed to have an outer diameter side that is expanded by the amount of the interference, and is in close contact with the annular groove 25 on the inner surface.

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.

On the other hand, in the case of the shape of the present invention shown in FIG. 5, since the pressure receiving area Am of the lip 10 is reduced, the thrust acting on the seal ring 5 is suppressed, and the heel 1
1 can reduce the surface pressure. Thereby, the deformation of the seal ring 5 can be reduced, and the heel corner 11i of the heel 11 can be prevented from protruding toward the piston rod 2 as much as possible. Oil leakage due to the scraping of hydraulic oil can be prevented.

On the other hand, it is also possible to increase the pressure acting on the lip 10, thereby eliminating the need for a pressure reducing member such as a buffer ring, which has conventionally been provided to limit the pressure on the seal ring 5. It is also possible.

Further, the outer shape of the intermediate portion 12 is
Tapered surface 12 that gradually expands toward heel 11 from
a, the pressure distribution of the lip portion 10 does not directly act on the support surface 11a of the heel portion 11, but the pressure distribution is also dispersed along the tapered surface 12a.
In 1, the pressure can be distributed over the entire support surface 11a of the heel portion 11. Therefore, the pressure acting on the heel portion 11 can be reduced by the area ratio to the pressure acting on the lip portion 10.

FIG. 6 shows a second embodiment. In this configuration, a backup ring 6 is disposed on the back surface of the seal ring 5, and the support surface 11a of the heel portion 11 of the seal ring 5 and the contact surface 6a of the backup ring 6 facing the support surface 11a are tapered. .

The support surface 11a of the heel portion 11 is formed in a tapered surface so that the outer diameter portion is farther from the lip portion 10 than the outer diameter portion.
By releasing the deformation of the seal ring 5 when the hydraulic oil pressure acts in the groove bottom direction, the surface pressure distribution on the support surface 11a can be made more uniform, and the corners 11 of the heel 11
i protruding in the direction of the piston rod, preventing biting more effectively, and the heel portion 11
The occurrence of abnormal surface pressure and surface pressure gradient 1i can be prevented.

In this embodiment, the tapered surface (contact surface 6a) is formed by using the backup ring 6 in consideration of the workability of the annular groove 25. However, the tapered surface is formed directly in the annular groove 25. Needless to say, this may be done.

FIG. 7 shows a third embodiment. This is the second
In the seal ring shown in the embodiment, when the pressure of the hydraulic oil is not applied between the tapered heel portion 11 of the seal ring 5 and the backup ring 6 holding the heel portion 11, the heel portion 11 The taper angles of the support surface 11a of the heel portion 11 and the abutment surface 6a of the backup ring 6 facing the support surface 11a are set to be different from each other so as to form a gap 13 that becomes larger toward the outer diameter direction. I have.

In this case, the deformation of the seal ring 5 can be guided more in the groove bottom direction than in the third embodiment, and the surface pressure and the surface pressure gradient on the piston rod 2 reduce the influence of the operating pressure of the heel portion 11. This makes it possible to realize a very stable sealing function which is hardly received.

FIG. 8 shows a fourth embodiment, which is a hydraulic oil for discharging the hydraulic oil between the outer peripheral portion of the seal ring 5 and the inner peripheral portion of the annular groove 25 to the heel portion 11 at atmospheric pressure. The groove 14 is provided.

This is because if the hydraulic oil enters the intermediate portion 12, the tapered surface 12a of the intermediate portion is also taken into account as the pressure receiving area of the lip portion 10, so that the pressure receiving area and the support area become substantially the same, and the lip portion 10 This prevents the effect of reducing the pressure receiving area from being lost.

With such a structure, the hydraulic oil remaining between the intermediate portion 12 of the seal ring 5 and the inclined wall portion 25b of the annular groove 25 is closer to the heel portion 11 at atmospheric pressure than the hydraulic oil drain groove 14. Therefore, the hydraulic oil presses the tapered surface 12a of the intermediate portion 12 to prevent the pressure receiving area from increasing.

FIG. 9 shows a fifth embodiment. In this embodiment, a seal ring 5 is provided on a piston 32 that slides with respect to a cylinder tube 34 as a support member. The basic configuration of the seal ring 5 is the same as that of the first embodiment.

In this case, the seal ring 5 is arranged such that the lip 10 faces the oil chamber on the side where more high pressure acts.
Place. Alternatively, when high pressure acts in both directions of the piston or the like, two seals are naturally arranged in opposite directions.

[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 cutaway 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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Piston rod 4 Bearing 5 Seal ring 6 Backup ring 10 Lip part 11 Heel part 12 Intermediate part 13 Clearance 14 Hydraulic oil drain groove

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masahide Kanda 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. F-term (reference) 3J006 AA01 AB02

Claims (7)

[Claims] 1. A sealing structure comprising: a sliding member; a supporting member that slidably supports the sliding member; and a seal ring interposed between the sliding member and the supporting member. The ring is housed in the storage recess, and has a lip on which the pressure of the hydraulic oil acts, and a heel for supporting the pressure acting on the seal ring on the wall surface of the storage recess. The inner circumference and the outer circumference of the lip Wherein the annular pressure receiving area is smaller than the annular supporting area between the inner periphery and the outer periphery of the heel portion. 2. The seal structure according to claim 1, wherein said seal ring is interposed in a support member. 3. The seal structure according to claim 1, wherein said seal ring is interposed in a sliding member. 4. The seal ring according to claim 1, wherein the heel portion of the seal ring has a tapered surface separated from the lip portion in a direction opposite to a sliding surface of the seal ring.
The seal structure according to any one of the above. 5. A holding member for holding a heel portion of a seal ring is interposed in the storage recess, and when a pressure of hydraulic oil is not applied between the contact surfaces, a sliding contact surface of the heel portion is provided. 5. A seal according to claim 1, wherein a gap is provided which increases in the opposite direction.
Structure. 6. The invention according to claim 1, wherein a tapered surface is formed on an outer periphery of an intermediate portion connecting the lip portion and the heel portion of the seal ring. Seal structure. 7. A hydraulic oil drain groove for guiding hydraulic oil to a heel portion between a tapered surface of the intermediate portion and an inner peripheral portion of a storage recess interposed with a seal ring is provided. 2. The seal structure according to 1.