JP2005240833A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device having high performance by which tension of a dust lip is maintained and a dust lip is protected even at long-term use and low-temperature use. <P>SOLUTION: The sealing device is equipped with a seal member 4 having an oil lip 2 on an oil side O brought into slide contact with a rod and a dust lip 3 on an atmosphere side A, an endless ring-shaped rubber ring 6 arranged in a recess 5 formed in a back surface of the dust lip 3, a first metal ring 7 fixed to a cylinder side of the seal member 4, and a second metal ring 8 having a cylinder part interposed between the first metal ring 7 and a cylinder and having a flange part 8a extended to the vicinity of the dust lip 3 on the atmosphere side A of the seal member 4 from the cylinder part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealing device used as a dust seal for preventing dust from entering a hydraulic cylinder used as an actuator of a construction machine or a transport vehicle.

  Conventionally, as shown in FIG. 4 described in Patent Document 1, the rod sealing system includes a buffer ring 101, a rod packing 201, and a dust seal 301. And in order to prolong the life of the system, different materials are used for each seal from the viewpoint of heat resistance, wear resistance, and oil resistance.

  In particular, when the dust seal 301 is used outdoors like a construction machine, the dust environment of external foreign matters such as mud and earth and sand is severe. For this reason, as shown in FIG. 5, the shape of the dust seal 301 is a split groove type in which a reinforcing ring 302 is bonded to the outer periphery, and a two-lip seal shape having an oil lip 303 and a dust lip 304 is used. High polyurethane material was used.

  In the dust seal 301 shown in FIG. 5, due to the interference of the dust lip 304, a tightening force “hereinafter referred to as an urging force” is generated on the shaft, thereby preventing external foreign matter from entering the cylinder. Further, the oil lip 303 has a function of sealing oil leaked from the rod seal, and leakage of oil to the outside is prevented. Furthermore, since the reinforcing ring 302 is bonded to the outer periphery of the dust seal 301 and the reinforcing ring 302 is incorporated by fitting with the mating groove, the entry of external foreign matter from the outer peripheral portion of the dust seal 301 is prevented.

In the dust seal 301 of FIG. 5, since a polyurethane material is used, the dusting force is increased due to a high Young's modulus, making it difficult for an external foreign object to enter the cylinder. In addition, the use of a polyurethane material is superior in friction resistance as compared with nitrile rubber and fluororubber, so that the reduction of the interference due to wear is suppressed and the life can be extended.
JP 2001-355739 A

  The purpose of the dust seal is to prevent external foreign matter from entering the cylinder. Therefore, it is necessary to maintain the tightening force (initial performance) due to the dusting margin of the dust lip and the maintenance of the tightening force (durability) due to maintenance of the interference.

  However, in the case of the prior art as described above, since the interference cost of the dust lip is reduced by long-term use, the tightness of the dust lip is reduced during long-term use. Further, the elasticity of the material is lowered even at low temperatures, and the tightness of the dust strip is reduced at low temperatures. In this way, when the tight force of the dust lip decreases, intrusion of external foreign matters becomes a problem. For this reason, it is required to maintain the tightness of the dust lip even during long-term use and low-temperature use.

  Further, as shown in FIG. 5, the dust lip is exposed to the outside of the atmosphere side A, and external dust may come into contact with the dust lip, resulting in damage to the dust lip. For this reason, it has been required to protect the dust lip.

The present invention has been made to solve the above-mentioned problems of the prior art, and the object of the present invention is to maintain the tightness of the dust lip even during long-term use and low-temperature use, and to protect the dust lip. The object is to provide a high-performance sealing device.

  In order to achieve the above object, the present invention seals the gap between two reciprocally moving two members, the oil-side oil lip and the atmosphere side slidingly contacting one of the two members A seal member having a dust strip, an endless ring-shaped elastic ring disposed in a recess formed on the back surface of the dust strip, a first reinforcing ring fixed to the other member side of the seal member, A second reinforcing ring having an axial portion interposed between the first reinforcing ring and the other member, and a flange portion extending from the axial portion to the vicinity of the dust strip on the atmosphere side of the seal member. It is characterized by that.

  In addition, the sealing member is made of polyurethane material, and the elastic ring is excellent in compression set at low temperature and low temperature property than polyurethane material, and it is preferable that the decrease in repulsive force is suppressed even during long-term use and low-temperature use. is there.

  According to the present invention, a repulsive force from the elastic ring is applied to the dust lip so as to increase the tightening force which is the tightening force of the dust lip, so that the dust squeezing force can be maintained even during long-term use and low-temperature use. Further, since the flange portion of the second reinforcing ring extends to the vicinity of the dust lip, the dust lip can be protected by the flange portion without being exposed to the atmosphere side, and the dust lip is prevented from being damaged, and the elastic ring is disposed. Since the flange portion covers the atmosphere side surface of the sealing member, the elastic ring can be prevented from falling off.

  The embodiment will be described with reference to FIGS. FIG. 1 is a half sectional view showing a sealing device according to an embodiment. FIG. 2 is a half cross-sectional view showing a state of a pressing force acting on the dust lip of the sealing device according to the embodiment. FIG. 3 is a half sectional view showing a sealing system using the sealing device according to the embodiment.

  The sealing device 1 of FIG. 1 is used for a hydraulic cylinder as a reciprocating seal, and is used for various sealing systems as shown in FIG. FIG. 3A shows a rod sealing system in which three seals are arranged in the order of a buffer ring 30, a rod seal 20, and a dust seal (sealing device 1). FIG. 3B shows a rod sealing system in which two seals are arranged in the order of a rod seal 20 and a dust seal (sealing device 1).

  In FIG. 3, the sealing device 1 is disposed on the most atmospheric side A of the sealing system and functions as a dust seal for reciprocating motion that prevents the dust on the atmospheric side A from entering the cylinder.

  As shown in FIG. 2, the sealing device 1 includes a rod 10 that is a relatively reciprocating shaft (one of two members) and a cylinder 11 that is a housing (the other member) that concentrically surrounds the rod 10. In order to seal the annular gap, it is mounted in the mounting groove at the end of the atmosphere A on the cylinder 11 and slidably contacts the surface of the rod 10.

  As shown in FIG. 1, the sealing device 1 includes a seal member 4 having two oil lips 2 and a dust lip 3 slidably sealingly contacted with a rod 10, and a recess 5 formed on the back surface of the dust lip 3. A rubber ring 6 that is an elastic ring disposed on the first ring, a first metal ring 7 that is a first reinforcement ring fixed to the seal member 4, and a second reinforcement interposed between the first metal ring 7 and the cylinder 11. And a second metal ring 8 which is a ring.

  The seal member 4 includes an oil lip 2 on the oil side O that extends obliquely toward the oil side O that slidably comes into contact with the surface of the rod 10, and an air side that also slidably comes into contact with the surface of the rod 10. A dust strip 3 on the atmosphere side A that is inclined and extended toward A. The sealing member 4 uses a polyurethane material as a material.

  Further, the seal member 4 is formed with a recess 5 that is open on the side surface of the atmosphere A as shown in FIG. The recess 5 is a space provided on the outer diameter side of the dust lip 3, that is, on the back surface of the dust lip 3, and is a recess opened on the atmosphere side A side surface of the seal member 4. In the case where the rubber ring 6 is not disposed in the concave portion 5, as shown in FIG. 2A, the tight force of the dust lip 3 becomes the tight force F1 of the dust lip 3 itself.

  The rubber ring 6 has no change in thickness, has a constant cross section on the circumference everywhere, and has an endless ring shape with no cut portion. When the rubber ring 6 is disposed in the recess 5, the surface pressure is as shown in FIG. A repulsive force F2 that is uniform on the circumference is generated. For this reason, when the rubber ring 6 is disposed, the tight force of the dust lip 3 is the tight force obtained by adding the repulsive force F2 of the rubber ring to the tight force F1 of the dust lip 3 itself as shown in FIG. (F1 + F2). Therefore, it is possible to give the rod 10 a tension force increased as F1 + F2 instead of a tension force similar to the conventional one. Further, the tension force of F1 + F2 is optimal for maintaining an oil film when reciprocating because the surface pressure on the circumference is uniform.

  In particular, the material of the rubber ring 6 is hydrogen nitrile rubber, silicon rubber, or nitrile rubber, which is superior in compression set at a high temperature and low temperature property (a material in which TR10 is lower than that of the polyurethane material). Therefore, a decrease in the repulsive force F2 of the rubber ring 6 can be suppressed during long-term use and low-temperature use, and the increased tension force F1 + F2 of the dust lip 3 can be maintained even during long-term use and low-temperature use.

  On the other hand, a first metal ring 7 is fixed to the fitting portion of the seal member 4 that holds the two oil lips 2 and the dust lip 3. The first metal ring 7 has a cylindrical shape having an inward flange portion 7a extending in the inner diameter direction at an oil side O end portion of a cylindrical portion as an axial direction portion, and is formed of SPCC or the like.

  Further, a cylindrical portion as an axial portion of the second metal ring 8 is interposed between the cylindrical portion of the first metal ring 7 and the cylinder 11, and the second metal ring 8 is inserted into the mounting groove of the cylinder 11. Mated. Contrary to the first metal ring 7, the second metal ring 8 has a cylindrical shape having an inward flange portion 8a extending in the inner diameter direction at the atmosphere side A end of the cylindrical portion, and is formed of SPCC or the like.

  The flange portion 8a of the second metal ring 8 extends inward from the cylindrical portion to the vicinity of the dust lip 3 near the surface of the rod 10, and covers the recess 5 of the seal member 4 in which the rubber ring 6 is disposed. .

  Therefore, the dust strip 3 can be protected without being exposed to the atmosphere side A by the flange portion 8 a of the second metal ring 8, the contact of an external foreign object to the dust strip 3 is prevented, and the dust strip 3 is prevented from being damaged. The rubber ring 6 is covered with the flange portion 8a so as not to be exposed to the outside, and the rubber ring 6 is prevented from falling off.

As described above, in the embodiment, a repulsive force from the rubber ring 6 is applied to the dust lip 3 to increase the tension force of the dust lip 3 to F1 + F2, so that the tension of the dust lip 3 is maintained even during long-term use and low-temperature use. You can maintain power. Further, since the flange portion 8a of the second metal ring 8 extends in the vicinity of the dust lip 3, the dust lip 3 can be protected by the flange portion 8a without being exposed to the atmosphere side A, and the dust lip 3 is prevented from being damaged. At the same time, since the flange portion 8a covers the atmosphere-side A side surface of the seal member 4 on which the rubber ring 6 is disposed, it is possible to prevent the rubber ring 6 from dropping off.

It is a half sectional view of the sealing device concerning an embodiment. It is a half cross-sectional view showing a state of tight force acting on the dust strip of the sealing device according to the embodiment. It is a half sectional view showing a sealing system using a sealing device concerning an embodiment. It is a half sectional view showing a sealing system using a conventional sealing device. FIG. 6 is a half sectional view of a prior art sealing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing device 2 Oil lip 3 Dustrip 4 Seal member 5 Recess 6 Rubber ring 7 1st metal ring 8 2nd metal ring 10 Rod 11 Cylinder

Claims (2)

Sealing a gap between two reciprocating members,
A seal member having an oil-side oil lip and an atmosphere-side dust lip that are in sliding contact with one of the two members;
An endless ring-shaped elastic ring disposed in a recess formed on the back surface of the dust lip,
A first reinforcing ring fixed to the other member side of the seal member;
A second reinforcing ring having an axial portion interposed between the first reinforcing ring and the other member, and a flange portion extending from the axial portion to the vicinity of the dust strip on the atmosphere side of the seal member;
A sealing device comprising: Sealing a gap between two reciprocating members,
A sealing member made of polyurethane material having an oil-side oil lip and an atmosphere-side dust lip that are in sliding contact with one of the two members;
Endless ring shape with excellent compression set and low-temperature properties at higher temperatures than polyurethane materials, and reduced reduction in repulsive force even during long-term use and low-temperature use. With an elastic ring,
A first reinforcing ring fixed to the other member side of the seal member;
A second reinforcing ring having an axial portion interposed between the first reinforcing ring and the other member, and a flange portion extending from the axial portion to the vicinity of the dust strip on the atmosphere side of the seal member;
A sealing device comprising:

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