JP2007247672A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device capable of suppressing wear of a sliding part while maintaining sealing property. <P>SOLUTION: This sealing device is mounted in an annular channel 40 provided in a shaft hole of a housing 4 to seal an annular clearance between the housing 4 and a shaft 5 inserted into the shaft hole and is provided with an annular resin member 2 provided with a projecting part 20 protruding toward the shaft 5 and having a tip coming into slide-contact with the shaft 5. The projecting part 20 is constituted so as to use a low pressure side slope 20a and a high pressure side slope as both hems. A part on a higher pressure side than the projecting part 20 of the resin member 2 leaves the shaft 5 due to pressure P from the high pressure side H, an inclination angle between the high pressure side slope of the projecting part 20 and a peripheral face of the shaft 5 is increased, a part on a lower pressure side than the projecting part 20 of the resin member 2 approaches the shaft 5, and the low pressure side slope 20a of the projecting part 20 adheres closely to the peripheral face of the shaft 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealing device used for, for example, a hydraulic cylinder used as an actuator of a construction machine or a transport vehicle.

  As a sealing device used for a hydraulic cylinder or the like, a sealing device 100 including a resin member 110 and an O-ring 120 as shown in FIG. The sealing device 100 is used as a sealing device for a rod of a hydraulic cylinder and is used for an inner peripheral sliding portion of the hydraulic cylinder, and is intended to prevent oil leakage to the outside.

  The resin member 110 is an annular member having a rectangular cross section made of a resin material such as tetrafluoroethylene (PTFE), and is attached to an annular groove 201 provided on the inner peripheral surface of the cylinder 200. The inner peripheral surface 111 is in sliding contact with the outer peripheral surface of the piston 300, and the low pressure side end surface 112 is in contact with the low pressure side wall 202 of the annular groove 201, thereby preventing oil leakage from the high pressure side H.

  Further, a rubber O-ring 120 is disposed between the resin member 110 and the groove bottom of the annular groove 201, and the resin member 110 is urged toward the piston 300 to urge the inner periphery of the resin member 110. The contact pressure between the surface 111 and the outer peripheral surface of the piston 300 is ensured.

  However, such a resin member has high pressure resistance and wear resistance, but has poor adhesion to the sliding mating surface and poor sealing performance, so oil leakage is not allowed (for example, recovering leaked oil) For example, it is difficult to apply to a use.

  Therefore, in order to improve the sealing performance while maintaining the pressure resistance and the wear resistance, as shown in FIG. Has been.

As shown in FIG. 4A, the resin member 110a has a sealing property with respect to the resin member 110 described above by increasing the gradient of the contact pressure gradient of the convex portion 113 in the contact pressure distribution Y. We are trying to improve.
JP 2001-349438 A JP 08-254272 A

  However, since the convex portion 113 has a small contact area with the mating sliding surface at the tip of the convex portion, a peak of contact pressure occurs near the tip of the convex portion. When the pressure on the high-pressure side H increases, as shown in FIG. 4 (b), the contact pressure at the tip of the convex portion increases, and the lubricity at the portion decreases, causing wear on the convex portion. End up.

  And if wear of the convex part 113 becomes large, the crimping allowance of the O-ring 120 will fall, the effect of ensuring the contact pressure by the O-ring 120 will fall, and the sealing performance will fall. Further, when the convex portion 113 is worn and the sliding area and the like are changed, the behavior of the resin member becomes unstable, which also causes a decrease in sealing performance.

  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 device that can suppress wear of a sliding portion while maintaining sealing performance. is there.

In order to achieve the above object, a sealing device according to the present invention comprises:
A sealing device that is attached to an annular groove provided in one member of a housing having a shaft hole and a shaft inserted into the shaft hole, and seals an annular gap between the two members,
In a sealing device provided with an annular resin member that protrudes toward the other member and that has a convex portion whose tip is in sliding contact with the other member,
The convex part is configured with a low-pressure side slope and a high-pressure side slope as both hems,
Due to the pressure from the high pressure side,
A portion on the high pressure side of the convex portion of the resin member is separated from the other member, and an inclination angle between the high pressure side inclined surface of the convex portion and the peripheral surface of the other member is increased.
A portion of the resin member on the low pressure side than the convex portion approaches the other member, and the low pressure side inclined surface of the convex portion is in close contact with the peripheral surface of the other member.

  In this way, when pressing, not only the tip of the convex portion but also the low-pressure side slope is brought into close contact with the mating member, so that the resin member comes into contact with the other member in a planar shape. Therefore, the contact pressure of the sliding part is reduced and wear of the sliding part is suppressed. In addition, the contact pressure peak decreases due to the contact with the surface, but the slope of the contact pressure gradient near the tip of the convex portion becomes steep as the inclination of the high-pressure side slope of the convex portion increases with respect to the other member. Sufficient sealing performance can be obtained.

A biasing member that biases the resin member toward the other member;
The resin member is inclined to the low pressure side as the high pressure side end surface and the low pressure side end surface go from the groove bottom side of the annular groove to the other member side, and as the groove bottom side peripheral surface goes from the high pressure side to the low pressure side, It is inclined to the groove bottom side of the annular groove,
When no pressure is applied, the urging force of the urging member causes the tip of the convex portion to be in close contact with the other member,
At the time of pressurization, the resin member pushes the tip of the convex portion by the pressure acting on the high pressure side end surface of the resin member and the high pressure side slope of the convex portion, and the biasing force of the biasing member acting on the circumferential surface on the groove bottom side. By rotating as a fulcrum, the low pressure side slope of the convex portion may be in close contact with the other member, and the low pressure side end surface of the resin member may be in close contact with the low pressure side wall of the annular groove.

  In this way, when no pressure is applied, the tip of the convex portion comes into contact with the mating member, so that the contact pressure at the tip of the convex portion rises and a peak of the contact pressure occurs near the tip of the convex portion. However, by rotating around the tip of the convex part, the low-pressure side slope of the convex part comes into contact with the mating member and comes into contact with the mating member on the surface.

  As described above, according to the present invention, wear of the sliding portion can be suppressed while maintaining the sealing performance, and the life of the sealing device can be extended.

  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. .

With reference to FIG. 1 and FIG. 2, the sealing device which concerns on an Example is demonstrated. FIG. 1 is a schematic cut surface obtained by cutting along the radial direction of the sealing device 10 according to the present embodiment. FIG.
It is typical sectional drawing which shows the mounting state of the sealing device which concerns on a present Example, (a) shows the state at the time of no pressure, (b) shows the state at the time of pressurization, respectively.

  A sealing device 1 according to the present embodiment is used as a rod packing for a hydraulic piston, and is composed of an annular resin member 2 and a rubber O-ring 3 disposed on the outer peripheral side thereof. (Housing) 4 is mounted in an annular groove 40 provided on the inner peripheral surface of the housing 4 to seal an annular gap between the inner peripheral surface of the cylinder 4 and the outer peripheral surface of the piston (shaft) 5. Prevent oil leakage to L.

  The resin member 2 is an annular member made of a resin such as tetrafluoroethylene (PTFE), the inner peripheral surface thereof is in sliding contact with the outer peripheral surface of the piston 5, and the end surface on the low pressure side L is the annular groove 40 of the cylinder 4. By closely contacting the low-pressure side wall, the annular gap between the inner peripheral surface of the cylinder 4 and the outer peripheral surface of the piston 5 is sealed.

  Although the basic shape of the resin member 2 is substantially rectangular, a convex portion 20 that protrudes toward the piston 5 is provided on the inner peripheral surface thereof. The convex portion 20 has a shape deviated along the axial direction, and the inclined surface 20 a on the low pressure side L of the inclined surfaces forming both hems thereof is slightly inclined from the outer peripheral surface of the piston 5 toward the annular groove 40. On the other hand, the inclined surface 20b on the high pressure side H is inclined from the outer peripheral surface of the piston 5 toward the annular groove 40 at a larger angle than the inclined surface 20a on the low pressure side.

  Further, both end surfaces 21 and 22 of the high pressure side H and the low pressure side L of the resin member 2 are inclined in the direction of the low pressure side L from the outer peripheral side toward the inner peripheral side (from the groove bottom side of the annular groove 40 to the piston 5 side). The outer peripheral surface 23 is inclined in the outer diameter direction (the groove bottom side of the annular groove 40) as it goes from the high pressure side H to the low pressure side L.

  The end surface 21 and the end surface 22 of the resin member 2, the outer peripheral surface 23, and the low-pressure side inclined surface 20a of the convex part 20 are formed substantially parallel to each other. A peripheral surface 24 substantially parallel to the outer peripheral surface of the piston 5 is formed between the high-pressure side end surface 21 and the high-pressure side inclined surface 20b of the convex portion 20 when no pressure is applied.

  The O-ring 3 is a biasing member that is disposed between the resin member 2 and the groove bottom of the annular groove 40 and biases the resin member 2 toward the piston 5, and has an outer diameter of the annular groove 40. By setting the diameter larger than the groove bottom diameter, compression is generated between the resin member 2 and the groove bottom of the annular groove 40, and an elastic force that urges the resin member 2 toward the piston 5 is generated.

  Next, the mounting state of the sealing device 1 will be described with reference to FIGS. 2 (a) and 2 (b).

  First, as shown in FIG. 2A, in the non-pressure state, only the convex portion 20 of the resin member 2 is in sliding contact with the outer peripheral surface of the piston 5, and a contact pressure distribution as shown by X in the figure is formed. Is done. That is, a contact pressure peak occurs near the tip of the convex portion 20.

  Next, when the pressure P is applied from the high pressure side H to be in a pressurized state, the force that the outer peripheral surface 23 receives in the inner diameter direction when the O-ring 3 is pushed into the low pressure side L, the high pressure side end surface 21, the high pressure side slope 20b and the pressure P received by the peripheral surface 24 from the high pressure side H cause the resin member 2 to rotate to the low pressure side L with the tip of the convex portion 20 as a fulcrum.

As a result, the resin member 2 has a portion on the high pressure side H away from the piston 5 with the tip of the convex portion 20 as a boundary, and a portion on the low pressure side L approaches the piston 5, as shown in FIG. The low pressure side inclined surface 20 a of the convex portion 20 comes into close contact with the outer peripheral surface of the piston 5, and the low pressure side end surface 22 comes into close contact with the low pressure side wall 41 of the annular groove 40. That is, the line contact by the tip of the convex part 20 is switched to the surface contact by the low-pressure side inclined surface 20a of the convex part 20.

  Then, the contact pressure at the sliding contact portion between the resin member 2 and the outer peripheral surface of the piston 5 is distributed such that a peak of the contact pressure occurs over the entire low pressure side inclined surface 20a of the convex portion 20, as indicated by X 'in the figure. Thus, the peak of the contact pressure is reduced as compared with the case where only the tip end portion of the convex portion 20 is in sliding contact even in the pressurized state as shown in FIG. Therefore, the contact pressure at the portion of the resin member 2 that slides on the outer peripheral surface of the piston 5 is reduced.

  Further, since the inclination angle of the high-pressure side inclined surface 20b of the convex portion 20 with respect to the outer peripheral surface of the piston 5 becomes larger than that in the non-pressure state due to the rotation of the resin member 2, the contact pressure gradient is further increased. The peak of the contact pressure becomes larger than that in the no-pressure state.

  That is, as compared with the case shown in FIG. 4B, the peak of the contact pressure is reduced by contacting the outer peripheral surface of the piston 5 with a surface, but sufficient contact pressure can be secured, and sufficient sealing performance is obtained. Can be obtained.

  Therefore, the friction of the sliding portion can be suppressed by reducing the contact pressure while ensuring sufficient sealing performance, and the life of the sealing device can be extended.

  In the present embodiment, both end faces 21 and 22 of the resin member 2 are formed substantially in parallel, but the present invention is not limited to this.

The typical sectional view of the sealing device concerning a present Example. The typical sectional view showing the wearing state of the sealing device concerning this example. The typical sectional view of the sealing device concerning a prior art. The typical sectional view showing the wearing state of the sealing device concerning the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing device 2 Resin member 3 O-ring 4 Cylinder 5 Piston X, X 'Contact pressure distribution

Claims (2)

A sealing device that is attached to an annular groove provided in one member of a housing having a shaft hole and a shaft inserted into the shaft hole, and seals an annular gap between the two members,
In a sealing device provided with an annular resin member that protrudes toward the other member and that has a convex portion whose tip is in sliding contact with the other member,
The convex part is configured with a low-pressure side slope and a high-pressure side slope as both hems,
Due to the pressure from the high pressure side,
A portion on the high pressure side of the convex portion of the resin member is separated from the other member, and an inclination angle between the high pressure side inclined surface of the convex portion and the peripheral surface of the other member is increased.
A sealing device, wherein a portion of the resin member on the low pressure side of the convex portion approaches the other member, and the low pressure side inclined surface of the convex portion is in close contact with the peripheral surface of the other member. A biasing member that biases the resin member toward the other member;
The resin member is inclined to the low pressure side as the high pressure side end surface and the low pressure side end surface go from the groove bottom side of the annular groove to the other member side, and as the groove bottom side peripheral surface goes from the high pressure side to the low pressure side, It is inclined to the groove bottom side of the annular groove,
When no pressure is applied, the urging force of the urging member causes the tip of the convex portion to be in close contact with the other member,
At the time of pressurization, the resin member pushes the tip of the convex portion by the pressure acting on the high pressure side end surface of the resin member and the high pressure side slope of the convex portion, and the biasing force of the biasing member acting on the circumferential surface on the groove bottom side. By rotating as a fulcrum, the low-pressure side slope of the convex portion is in close contact with the other member, and the low-pressure side end surface of the resin member is in close contact with the low-pressure side wall of the annular groove. Item 2. The sealing device according to Item 1.

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