JP2010054021A - Sealing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing system improved in reliability. <P>SOLUTION: The sealing system 1 is provided for sealing an annular clearance between an inner peripheral face 301 of a cylinder 300 and an outer peripheral face 201 of a piston 200 which is reciprocated inside the cylinder. It includes a sliding ring 11 mounted in an annular groove 202c of the piston 200 for slidably contacting the inner peripheral face 301 of the cylinder 300, an energizing member 12 mounted between the sliding ring 11 and the groove bottom of the annular groove 202c for energizing the sliding ring 11 toward the inner peripheral face 301 of the cylinder 300, and a pair of seal members 20a, 20b mounted in a pair of annular grooves 202a, 202b provided on both axial sides of the annular groove 202c, having seal lips for slidably contacting the inner peripheral face 301 of the cylinder 300, and formed of rubber elastic materials, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sealing system for sealing an annular gap between a shaft that moves relative to each other in the axial direction and a housing having a shaft hole into which the shaft is inserted.

  2. Description of the Related Art Conventionally, a hydraulic cylinder uses a sealing system for sealing an annular gap between an outer peripheral surface of a piston that reciprocates in the cylinder and an inner peripheral surface of the cylinder. Various configurations of such sealing systems have been proposed so far (see Patent Documents 1 to 4).

  A sealing system according to the prior art will be described with reference to FIGS. FIG. 3 is a schematic half sectional view of a sealing system according to the prior art. FIG. 4 is a schematic half sectional view of a sealing system according to another prior art.

  The sealing system shown in FIG. 3 includes two lip packings 100a and 100b made of an elastic body such as rubber and urethane, and two backup rings 101a and 101b made of a resin material such as PTFE and nylon. The lip packings 100a and 100b and the backup rings 101a and 101b are respectively mounted in annular grooves 202a and 200b provided in the axial direction on the outer peripheral surface 201 of the piston 200, and the outer peripheral surface 201 of the piston 200 and the inner peripheral surface of the cylinder 300 Seal the annular gap with 301. Note that the backup rings 101a and 101b are used together under high-pressure applications and are not necessarily required.

  The internal space of the cylinder 300 is divided into two regions by the piston 200, and the pressure in the space (A) on one side in the axial direction (left side in the figure) and the space (B in the right side in the figure) (B The pressure relationship in parentheses) alternately reverses in elevation every time the piston 200 reciprocates.

  When the space (A) is on the high pressure side, the lip packing 100a disposed on the space (A) side mainly seals the annular gap between the cylinder 300 and the piston 200. That is, the seal lip of the lip packing 100a receives a high pressure from the space (A) and slidably contacts the inner peripheral surface 301 of the cylinder 300 and closely contacts the groove bottom surface of the annular groove 202a. When the space (B) is on the high pressure side, the lip packing 100b disposed on the space (B) side mainly seals the annular gap between the cylinder 300 and the piston 200. That is, the seal lip of the lip packing 100b receives a high pressure from the space (B) and slidably contacts the inner peripheral surface 301 of the cylinder 300 and closely contacts the groove bottom surface of the annular groove 202b.

  The sealing system shown in FIG. 4 includes a pair of combination seals 100c in which a resin ring 101c made of a resin material such as PTFE or nylon and a rubber ring 102c made of rubber, urethane or the like are combined. In this sealing system, the outer peripheral surface of the resin ring 101c is slidably in contact with the inner peripheral surface of the cylinder 300, and the low-pressure side surface (end surface in the axial direction) of the resin ring 101c is annular when receiving pressure from the high-pressure side. The annular gap between the cylinder 300 and the piston 200 is sealed by a single seal member by being in close contact with the measurement wall surface on the low pressure side of the groove 202c.

Compared with the sealing system shown in FIG. 4, the sealing system shown in FIG. 3 has a thin oil film that passes through the sealing system when the piston 200 reciprocates, and slides on the inner peripheral surface 301 of the cylinder 300. Since the moving member is highly flexible, it can easily follow the roughness of the inner peripheral surface 301 and is excellent in terms of sealing performance. In addition, since the sealing system shown in FIG. 4 is configured to receive pressure in both directions with one seal member, so-called blow-through leakage (passing) may occur, but the sealing system shown in FIG. The member is configured to receive pressure from only one direction, and there is no fear of blowout leakage.

  On the other hand, as compared with the sealing system shown in FIG. 3, the sealing system shown in FIG. 4 is superior in wear resistance because the member that slides on the inner peripheral surface 301 of the cylinder 300 is a resin material. Further, since the pressure in both directions can be sealed with one seal member, there is a concern that the seal member may be damaged by the accumulated pressure generated in the space between the two seal members as in the sealing system shown in FIG. There is no.

  However, both the sealing system shown in FIG. 3 and the sealing system shown in FIG. 4 are particularly damaged when the seal member is damaged due to burning, improper roughness of the mating sliding surface, insufficient lubrication, high pressurization frequency, minute strokes, etc. In the case of the sealing system shown in FIG. 3, if any one of the sealing members is broken, internal leakage of the piston portion occurs, resulting in a malfunction of the hydraulic cylinder. In the seal ring shown in FIG. 4, a resin material such as nylon may be applied to the sliding member under a high pressure application. However, nylon has a high coefficient of friction. A stick slip may occur between the piston and the cylinder due to the influence of the above.

Therefore, in the sealing system used for the piston portion of the hydraulic cylinder, further improvement in reliability is required.
Japanese Utility Model Publication No. 58-0119164 Japanese Utility Model Publication No. 60-058964 Japanese Utility Model Publication No. 60-101265 Japanese Utility Model Publication No. 04-136364

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a sealing system with improved reliability.

In order to achieve the above object, the sealing system of the present invention comprises:
A sealing system for sealing an annular gap between a shaft that reciprocally moves relative to each other in an axial direction and a housing having a shaft hole into which the shaft is inserted, and the sealing system every time the reciprocating direction of two members changes In a sealing system used in an environment where the high-low relationship between the pressure in the region on the one axial side and the pressure in the other axial side is reversed,
A sliding ring mounted in a first annular groove provided in one of the two members and slidably contacting the surface of the other member;
A biasing member mounted between the sliding ring and a groove bottom of the annular groove, and biasing the sliding ring toward the surface of the other member;
A rubber-like elastic member that is attached to a pair of second annular grooves provided on both sides in the axial direction of the first annular groove and has a seal lip that slidably contacts the surface of the other member. A pair of sealing members comprising a body;
It is characterized by providing.

According to such a configuration, the seal members made of rubber-like elastic bodies are arranged on both sides in the axial direction of the sliding ring and the urging member, so that pressure from the high pressure side does not directly act on the sliding ring. Therefore, even when burrs or sink marks are generated on the sliding surface of the sliding ring or the surface roughness is large, the sliding ring may be excessively pressed against the surface of the other member by the pressure from the high pressure side. Therefore, the occurrence of stick-slip is suppressed.

  In addition, pressure is applied to each seal member from only one direction, and the sliding ring and the biasing member are not in a state in which pressure is applied from both directions. There is nothing.

  In addition, when the sealing performance of the seal member deteriorates or is lost due to long-term use, pressure from the high pressure side acts directly on the sliding ring, but at that point, sliding occurs due to the influence of running-in due to sliding. Since the burrs, sink marks, and surface roughness of the sliding surface of the ring are reduced and the sliding of the resin ring is smooth, the occurrence of stick-slip is also suppressed in this case.

  That is, stable operating characteristics can be obtained from the initial use to a long period of time, and the reliability of the sealing system can be improved.

  The pair of seal members is configured to apply pressure in a region between the seal member, the sliding ring, and the biasing member in the annular gap to the tip of the seal lip, or the region on the one axial side or the shaft It is good to have a notch part which can escape in the field on the other side in the direction.

  As a result, even if the pressure in the region between the seal member and the sliding ring and the biasing member in the annular gap increases, it is possible to avoid damage to the sealing member and the sliding ring due to accumulated pressure. The reliability can be further improved.

  As described above, according to the present invention, the reliability of the sealing system can be improved.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

(Example)
With reference to FIG.1 and FIG.2, the sealing system based on the Example of this invention is demonstrated. FIG. 1 is a schematic half sectional view of a sealing system according to an embodiment of the present invention. FIG. 2 is a schematic half-sectional view of a sealing member constituting a sealing system according to an embodiment of the present invention. FIG. 2A is a schematic diagram of a lip packing arranged on one space side inside a cylinder partitioned by a piston. (B) is a schematic half sectional view of a combination seal disposed between a pair of lip packings, (c) is a schematic half sectional view of a lip packing disposed on the other space side inside the cylinder. It is.

<Entire sealing system configuration>
As shown in FIG. 1, the sealing system 1 according to the present embodiment is for sealing an annular gap between an outer peripheral surface 201 of a piston 200 and an inner peripheral surface 301 of a cylinder 300. The sealing system 1 includes a combination seal 10 and a pair of lip packings 20a and 20b arranged on both sides in the axial direction. The combination seal 10 is attached to an annular groove 202 c provided at a substantially central portion of the outer peripheral surface 201 of the piston 200. Lip packing 20a
, 20b are attached to the annular grooves 202a, 202b provided on both sides in the axial direction of the annular groove 202c to which the combination seal 10 is attached.

  The space inside the cylinder 300 is divided into two spaces (A) and (B) by the piston 200. In the piston 200, pressure is introduced into the cylinder 300 via a port (not shown) provided in the cylinder 300, and the pressure of the hydraulic oil in one space is increased with respect to the pressure of the hydraulic oil in the other space. Thus, the cylinder 300 is configured to reciprocate. Therefore, the space on the high pressure side and the space on the low pressure side with respect to the sealing system 1 are switched each time the reciprocating direction of the piston 200 changes.

<Composition of combination seal>
As shown in FIG. 2B, the combination seal 10 includes a sliding ring 11 and a back ring 12 as an urging member.

  The sliding ring 11 is an annular member made of a resin material such as PTFE or nylon, and is disposed on the groove opening side of the annular groove 202 c, and its outer peripheral surface is slidably in contact with the inner peripheral surface 301 of the cylinder 300. . Further, when the pressure from the high pressure side does not act directly, the sliding ring 11 is pushed in the direction opposite to the moving direction of the piston 200 by receiving sliding resistance with the inner peripheral surface 301 of the cylinder 300. The side surface (axial end surface) on the direction side is in close contact with the side wall surface of the annular groove 202c. Further, when the pressure on the high pressure side acts directly due to deterioration or loss of the sealing performance of the lip packings 20a and 20b, the pressure acting on the high pressure side is pushed into the low pressure side, and the side surface on the low pressure side is an annular groove. It closely adheres to the side wall surface of 202c. In the drawing, although there is no gap between the side surface of the sliding ring 11 and the side wall surface of the annular groove 202c, a configuration with a gap may be used.

  The back ring 12 is an annular member made of an elastic body such as rubber or urethane, and is mounted in a compressed state between the inner peripheral surface of the sliding ring 11 and the groove bottom surface of the annular groove 202c. By energizing the inner peripheral surface 301 of 300, the adhesion between the sliding ring 11 and the inner peripheral surface 301 of the cylinder 300 is enhanced.

<Configuration of lip packing>
The lip packing 20a disposed on the space (A) side with respect to the combination seal 10 is an annular member made of an elastic body such as rubber or urethane, and mainly exhibits a sealing function when the space (A) is on the high pressure side. Is configured to do.

  As shown in FIG. 2A, the lip packing 20a has seal lips 21a and 22a extending substantially in the axial direction toward the space (A). The seal lip 21 a provided on the outer peripheral side of the lip packing 20 a is in slidable contact with the inner peripheral surface 301 of the cylinder 300. The seal lip 22a provided on the inner peripheral side of the lip packing 20a is in close contact with the groove bottom surface of the annular groove 202a. Between the seal lip 21a and the seal lip 22a, it has a shape like a groove opened in the space (A), and pressure acts from the space (A) side, so that the adhesion of each seal lip 21a, 22a is It can be enhanced.

  Further, notches 23a and 24a are provided at the tips of the seal lips 21a and 22a, respectively, for preventing pressure accumulation damage. That is, when the oil film remains in the space between the lip packing 20a and the combination seal 10 due to the reciprocating motion of the piston 200 and the pressure in the space rises (accumulation of pressure), the tips of the seal lips 21a and 22a are annular. Even when it comes into contact with the side surface of the groove 202a, a passage that opens the increased pressure to the space (A) side is formed.

  Further, the lip packing 20b disposed on the space (B) side with respect to the combination seal 10 has a symmetric configuration with the lip packing 20a, and mainly has a sealing function when the space (B) is on the high pressure side. It is an annular member made of an elastic body such as rubber or urethane, which is configured to exhibit.

  As shown in FIG. 2C, the lip packing 20b has seal lips 21b and 22b extending substantially in the axial direction toward the space (B). The seal lip 21b provided on the outer peripheral side of the lip packing 20b slidably contacts the inner peripheral surface 301 of the cylinder 300. The seal lip 22b provided on the inner peripheral side of the lip packing 20b is in close contact with the groove bottom surface of the annular groove 202b. Between the seal lip 21b and the seal lip 22b, it has a shape like a groove opening in the space (B), and pressure acts from the space (B) side, so that the adhesion of each seal lip 21b, 22b is It can be enhanced.

  Further, notches 23b and 24b for preventing pressure accumulation damage are provided at the tips of the seal lips 21b and 22b, respectively, similarly to the seal lips 21a and 22a of the lip packing 20a.

  In this embodiment, backup rings 30a and 30b are mounted between the side surfaces of the lip packings 20a and 20b, which are on the low pressure side when pressurized, and the side walls of the annular grooves 202a and 202b, respectively. These backup rings 30a and 30b are used together when the pressure acting on the lip packings 20a and 20b is high, and are not necessarily required, and may not be used under low-pressure applications.

<Excellent points of this embodiment>
In the sealing system according to the present embodiment, the pressure from the high pressure side does not directly act on the combination seal provided with the sliding seal portion made of a resin material in the initial use state.

  That is, since the lip packing made of a rubber-like elastic body is disposed on both sides of the sliding ring and the back ring in the axial direction, the pressure from the high pressure side is maintained while the lip packing exhibits sealing performance. Does not act directly on the sliding ring. Therefore, even when burrs or sink marks are generated on the sliding surface of the sliding ring or the surface roughness is large, the sliding ring may be excessively pressed against the surface of the other member by the pressure from the high pressure side. Therefore, the occurrence of stick-slip is suppressed.

  In general, a seal member used in a hydraulic device is configured to increase an adhesion force with a mating member by obtaining an expansion force due to pressure from a high pressure side. Is in a state where positive pressure and back pressure occur (the occurrence of positive pressure and back pressure), the seal member cannot obtain sufficient expansion force, and the contact state with the mating member becomes insufficient, and the hydraulic oil on one region side It is known that a phenomenon of leaking so as to blow through the sliding surface to the other region side occurs (blow-through leakage). However, according to the configuration of the sealing system according to the present embodiment, each lip packing is applied with pressure from only one direction, and pressure is applied to the sliding ring and the buckling from both directions. Since it does not become such a state, a blow-through leak does not occur.

  In addition, when the sealing performance of the lip packing deteriorates or is lost due to sticking of the seal lip due to long-term use, pressure from the high pressure side directly acts on the sliding ring, but at that time, due to sliding The burr and sink marks on the sliding surface of the sliding ring and the surface roughness are reduced by the influence of the running-in, and the sliding of the sliding ring is smooth, so that the occurrence of stick-slip is also suppressed in this case .

  That is, stable operating characteristics can be obtained from the initial use to a long period of time, and the reliability of the sealing system can be improved.

  In addition, since a notch for preventing pressure accumulation damage is provided at the tip of the seal lip of the lip packing, the pressure in the space between the lip packing and the combination seal (sliding ring and back ring) in the annular gap is reduced. Even if it rises, it becomes possible to avoid damage to the lip packing and the sliding ring due to pressure accumulation. Therefore, the reliability of the sealing system can be further improved.

  Burnout is caused by adiabatic compression of residual air, but according to this embodiment, air can be sealed by the lip packing, so that at least the combination seal disposed at the center can avoid burnout. Therefore, the sealing performance as a whole sealing system can be maintained for a long time.

  In the above embodiment, the sealing system for sealing the piston portion of the hydraulic cylinder has been described as an example, but the configuration of the mating member to which the sealing system of the present invention can be applied is not limited to this, and the reciprocating motion of the mating member It can be suitably used in an environment where the high and low relationship between the pressure in the region on the one axial side and the pressure on the other side in the axial direction reverses each time the direction changes.

1 is a schematic half sectional view of a sealing system according to an embodiment of the present invention. It is a typical half section view of the sealing member which constitutes the sealing system concerning the example of the present invention. It is a typical half sectional view of the sealing system concerning a prior art. It is a typical half section view of other sealing systems concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing system 10 Combination seal 11 Sliding ring 12 Back ring 20a, 20b Lip packing 30a, 30b Backup ring 200 Piston 201 Outer surface 202a, 202b, 202c Annular groove 300 Cylinder 301 Inner surface

Claims (2)

A sealing system for sealing an annular gap between a shaft that reciprocally moves relative to each other in an axial direction and a housing having a shaft hole into which the shaft is inserted, and the sealing system every time the reciprocating direction of two members changes In a sealing system used in an environment where the high-low relationship between the pressure in the region on one axial side and the pressure in the other axial side is reversed,
A sliding ring mounted in a first annular groove provided in one of the two members and slidably contacting the surface of the other member;
A biasing member mounted between the sliding ring and a groove bottom of the annular groove, and biasing the sliding ring toward the surface of the other member;
A rubber-like elastic member that is attached to a pair of second annular grooves provided on both sides in the axial direction of the first annular groove and has a seal lip that slidably contacts the surface of the other member. A pair of sealing members comprising a body;
A sealing system comprising:   The pair of seal members is configured to apply pressure in a region between the seal member, the sliding ring, and the biasing member in the annular gap to the tip of the seal lip, or the region on the one axial side or the shaft The sealing system according to claim 1, further comprising a notch that can be released in a region on the other side in the direction.

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