JPH0534362U - Sealing device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the increase of frictional resistance between the seal lip and the mating member. [Structure] An annular fixing portion 7 and 17 fixed to the inner circumference of the housing 2 and an annular main seal lip 12 extending in the axial direction toward the oil A side for sealing contact with the shaft 13 are provided. A pressure relief chamber B communicating with the oil A and the atmosphere D is provided, and a check valve 11 opened by the pressure increase of the oil A is provided between the oil A and the pressure relief chamber B to connect the pressure relief chamber B and the atmosphere D. In the meantime, when the pressure relief chamber B is at a low pressure, the pressure relief chamber B is sealed without contact with the shaft 13, and when the pressure relief chamber B is at a high pressure, the pressure relief chamber B is hermetically contacted with the shaft 13 to increase the volume of the pressure relief chamber B. The auxiliary seal lip 18 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sealing device used in a place where the pressure of a sealed fluid chamber becomes intermittent or sometimes high.

[0002]

[Prior Art]

 FIG. 2 shows a first conventional example. That is, the oil seal 100 has one member, that is, the annular fixing portion 102 fitted to the inner circumference of the housing 101. On the inner peripheral side of the fixed portion 102, the other member, that is, the main seal lip 104 made of a rubber-like elastic body that comes into sealing contact with the shaft 103 extends in the axial direction toward the sealed fluid chamber X side. A spring 105 is attached to the back surface of the main seal lip 104.

A dust-repelling lip 106 is provided on the side of the main seal lip 104 on the side of the separate fluid Y. The sealing surface formed by the main seal lip 104 and the shaft 103 seals the fluid (oil or the like) in the sealed fluid chamber X. Incidentally, 107 is a metal ring embedded in the fixed portion 102.

FIG. 3 shows an oil seal 200 as a second conventional example. The fixed portion 201 is fitted into a housing 202 as one member, and a metal ring 203 is joined to the fixed portion 201. A seal ring 204 made of a rubber-like elastic material is provided on the inner circumference of the metal ring 203, and a seal lip 205 extending axially toward the sealed fluid chamber X is provided on the inner circumference of the seal ring 204. .. The seal lip 205 contacts the shaft 206 as the other member to form a sealing surface.

Further, a spring 207 is attached to the back surface of the seal lip 205. A ring 208 having a V-shaped cross section is attached to the inner circumference of the metal ring 203, and the ring 208 has an inner diameter such that the inner circumference reaches the vicinity of the shaft 206. On the other hand, a dustproof lip 209 is provided on the side of the separate fluid Y of the fixed portion 201.

Then, the fluid in the sealed fluid chamber X is sealed by the sealing surface formed by the seal lip 205. Further, when the pressure in the sealed fluid chamber X rises, the pressure is received by the ring 208 and is not applied to the seal lip 205 properly.

[0007]

[Problems to be solved by the device]

 However, in the above-mentioned first conventional example, when the pressure of the sealed fluid chamber X rises, the pressure acts directly on the back surface of the main seal lip 104 in the radial direction, so that the main seal lip 104 is deformed and the axial direction is Friction resistance with 103 increases. As a result, the main seal lip 104 may be worn in a short period of time, the durability may be reduced, and the sealing performance of the sealing surface may be impaired.

By the way, it may be considered to increase the rigidity of the main seal lip 104 in order to prevent the deformation, but the followability to the eccentricity of the shaft 103 deteriorates and early wear occurs, and the loss of the rotational torque of the shaft 103 occurs. There are problems such as becoming large.

Further, in the second conventional example, since the ring 208 is provided, the pressure increase in the sealed fluid chamber X does not directly act on the seal lip 205, but fluid exists between the ring 208 and the seal lip 205. However, eventually, the seal lip 205 is worn and the sealing performance is deteriorated due to the increase in pressure.

Even if the rigidity of the seal lip 205 is increased, the same problem as described above is caused, which is not preferable.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a sealing device capable of preventing an increase in the friction resistance between the seal lip and the other member.

[0012]

Means for Solving the Problems To achieve the above object, the present invention is to provide an annular fixing portion, which is disposed between two members which are movable relative to each other, and which is attached to one member, and sealingly contacts the other member. A pressure relief chamber that has an annular main seal lip that extends in the axial direction toward the sealed fluid chamber, and that connects the sealed fluid chamber and another fluid chamber, and provides a space between the sealed fluid chamber and the pressure relief chamber. A valve that opens when the pressure in the sealed fluid chamber rises is installed to seal the pressure relief chamber between the pressure relief chamber and another fluid chamber without contact with the other member when the pressure relief chamber is at a low pressure, and It is characterized in that a sub seal lip is provided which expands the volume of the pressure relief chamber by sealingly contacting the other member when the relief chamber is under high pressure.

[0013]

[Action]

 The function of the present invention based on the above configuration is that the valve is closed and the auxiliary seal lip is separated from the other member to seal the pressure relief chamber when the pressure of the sealed fluid chamber is low. The sealed fluid chamber and the separate fluid chamber are sealed by a single sealing surface formed by the main seal lip and the other member.

On the other hand, when the pressure of the sealed fluid chamber becomes high, the valve is opened and the pressure is transmitted to the pressure relief chamber, so that the pressure rise in the sealed fluid chamber is prevented. Therefore, the frictional resistance between the main seal lip and the other member does not change.

Further, due to the pressure increase in the pressure relief chamber, the auxiliary seal lip comes into contact with the other member to form the second sealing surface, and the volume of the pressure relief chamber is expanded.

[0016]

【Example】

 Next, the present invention will be described with reference to FIG. In the figure, 1 indicates an oil seal to which the present invention is applied. The oil seal 1 is fitted and fixed to the inner periphery of a housing 2 as one member, and is divided into a first seal ring 3 and a second seal ring 4 in the axial direction.

The first seal ring 3 is located in the sealed fluid chamber in the housing 2, for example, the oil A side, and the second seal ring 4 is located in another fluid chamber, for example, the atmosphere D side. A retaining ring 50 fixed by a bolt or the like (not shown) is provided on the end surface of the housing 2 so that the oil seal 1 does not fall off the housing 2.

The first seal ring 3 has a seal body 5 made of a rubber-like elastic body and a metal ring 6 embedded in the seal body 5 and having an L-shaped cross section. On the outer peripheral surface of the annular fixing portion 7 which constitutes the outer peripheral side of the seal body 5, a pressure passage groove 8 is formed which is cut out along the axial direction.

There is a predetermined gap between the inward flange 9 of the first seal ring 3 and the inward flange (discussed below) 10 of the second seal ring 4 to form an annular pressure relief chamber B. There is. The oil A side and the pressure relief chamber B communicate with each other through the pressure passage groove 8.

Further, between the oil A side and the pressure relief chamber B, that is, on the outer periphery of the inward flange 9, a check valve 11 that is opened by a pressure increase on the oil A side is provided. The check valve 11 is made of a rubber-like elastic body integrally formed with the inward flange 9, and has a lip shape that is inclined annularly toward the second seal ring 4 side. The check valve 11 is in close contact with the inner circumference of the housing 2 by rubber elasticity when the oil A side has a low pressure, and fluid-tightly shuts off the oil A side and the pressure relief chamber B.

On the oil A side at the inner peripheral end of the inward flange 9, an annular main seal lip 12 extending in the axial direction toward the oil A side is integrally formed. The main seal lip 12 is set to an inner diameter that produces a predetermined interference with the shaft 13 and forms a first sealing surface E. A spring 14 is attached to the back surface of the main seal lip 12. The inner peripheral surface 9 a of the inward flange 9 has an inner diameter that forms a predetermined gap with the shaft 13.

On the other hand, the second seal ring 4 has a seal body 15 made of a rubber-like elastic body, and a metal ring 16 embedded in the seal body 15. An annular fixing portion 17 which constitutes the outer peripheral side of the seal body 15 is fitted in the housing 2 and is set to have substantially the same outer diameter as the fixing portion 7 of the first seal ring. The inner diameter of the fixed portion 17 is set to be larger than the inner diameter of the retaining ring 50.

The inward flange 10 is integrally formed on the inner peripheral side of the fixed portion 17, and the inner peripheral end of the inward flange 10 on the oil A side is moved to the oil A side. An annular auxiliary seal lip 18 extending in the axial direction is integrally formed. The outer diameter of the sub seal lip 18 is set to be substantially the same as the inner diameter of the inner peripheral surface 9a of the inward flange 9, and the axial length that the end face of the inward flange 9 enters into the main seal lip 12 side. It is equipped with

Therefore, when the pressure relief chamber B has a low pressure, the auxiliary seal lip 18 is set to have an inner diameter such that the outer peripheral surface thereof contacts the inner peripheral surface of the inward flange 9 and does not contact the shaft 13 as indicated by the solid line. I am doing it.

In the above configuration, when the oil A side has a low pressure (approximately the same pressure as the atmosphere D), the check valve 11 is in close contact with the housing 2 due to rubber elasticity and is in a closed state. It is fluid-tightly isolated from B. For this reason, the pressure relief chamber B is also at a low pressure, and the rigidity of the sub seal lip 18 makes close contact with the inner peripheral surface of the inward flange 9a to fluid-tightly isolate the pressure relief chamber B from the atmosphere D side. .. A first sealing surface E is formed by the main seal lip 12 and the shaft 13, and the oil A is sealed by the sealing surface E.

When the oil A becomes high in pressure, the pressure P is applied to the outer peripheral surface of the check valve 11 via the pressure passage groove 8 as indicated by the arrow, and the check valve 11 is directed to the inner peripheral side as indicated by the dotted line. It elastically deforms and opens, and the oil A side communicates with the pressure relief chamber B. Then, the pressure in the pressure relief chamber B becomes high, and the pressure P acts on the outer peripheral surface of the sub seal lip 18 in the radial direction.

As a result, the sub-seal lip 18 elastically deforms toward the inner peripheral side against the rigidity, separates from the inner peripheral surface 9a of the inward flange 9 and contacts the shaft 13 as shown by the dotted line, (2) The sealed surface F is formed. Then, a pressure retention chamber G surrounded by the main seal lip 12, the inner peripheral surface 9a, the sub seal lip 18, and the shaft 13 is formed. That is, the volume of the pressure relief chamber B 1 increases.

In this way, the pressure of the oil A decreases, and the pressures of the pressure relief chamber B and the pressure retention chamber G become equal to this. In this way, the radial pressure applied to the main seal lip 12 can be constantly kept constant. Therefore, the frictional resistance between the main seal lip 12 and the shaft 13 does not fluctuate, the durability of the main seal lip 12 can be improved and the sealing performance can be maintained, and the rotation torque of the shaft 13 is not lost.

Further, since the pressure relief chamber B has the same pressure as the oil A side, the auxiliary seal lip 18 is not worn. Since the second sealing surface F is formed by the sub seal lip 18, the oil A does not leak to the atmosphere D side.

On the other hand, when the pressure of the oil A decreases, the check valve 11 returns to the solid line state again due to rubber elasticity, and the pressure P also decreases and the auxiliary seal lip 18 also changes to the solid line state due to the rigidity. Will be back. At this time, since the oil in the pressure retention chamber G is sucked into the oil A side through the sealing surface E by the pumping action of the main seal lip 12, there is no concern that the oil is taken to the atmosphere D side.

The sealed fluid is not limited to oil and may be water or the like. Also, the shaft may be reciprocating instead of rotating. Further, the oil seal may be fixed to the shaft and the seal lip may be in contact with the inner circumference of the housing. Furthermore, the first and second seal rings may be integrally molded.

[0032]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, when the pressure of the sealed fluid chamber becomes high, the valve opens and the pressure is released to the pressure relief chamber. Therefore, the pressure of the sealing fluid applied to the main seal lip can always be kept constant, and the frictional resistance with the other member does not fluctuate. Therefore, the durability of the main seal lip can be improved and the hermeticity can be maintained.

[Submission date] January 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029] The Contact, for the sub-seal lip 18 forms a second sealing surface F, is not the oil A is leakage to the atmosphere D side.

[Brief description of drawings]

FIG. 1 is a half sectional view of an oil seal to which the present invention is applied.

FIG. 2 is a half sectional view of a first conventional example.

FIG. 3 is a half sectional view of a second conventional example.

[Explanation of symbols]

 1 oil seal 2 housing 3 first seal ring 4 second seal ring 50 retaining ring 6,16 metal ring 7,17 fixing part 8 pressure passage groove 9,10 inward flange 9a inner peripheral surface 11 check valve 12 main seal lip 13 shaft 14 spring 5,15 seal body 18 sub seal lip A oil B pressure relief chamber D atmosphere E first sealing surface F second sealing surface G pressure retention chamber P pressure

Claims (1)

[Scope of utility model registration request] 1. An annular fixing portion which is disposed between two members which are movable relative to each other and which is attached to one member, and an annular main portion which extends axially toward a sealed fluid chamber for sealing contact with the other member. A seal lip is provided, a pressure relief chamber that communicates the sealed fluid chamber and another fluid chamber is provided, and a valve that is opened by the pressure increase of the sealed fluid chamber is provided between the sealed fluid chamber and the pressure relief chamber, Between the pressure relief chamber and another fluid chamber, when the pressure relief chamber is at low pressure, it seals the pressure relief chamber without contact with the other member, and when the pressure relief chamber is at high pressure, it seals and contacts the other member and pressure is applied. A sealing device provided with an auxiliary seal lip for expanding the volume of the escape chamber.