JP2004036631A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device having high reliability, improved quality, and extended service life. <P>SOLUTION: A back-up ring 10 has a projection 10b projecting toward a main lip section 8a on a shaft 3 side on a side surface of a ring body 10a. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing device for sealing an annular gap between two members provided reciprocally with each other.
[0002]
[Prior art]
Conventionally, in a shaft sealing portion or the like of a device on which a sealing fluid acts, for example, as shown in the cross-sectional configuration explanatory view of FIG. 4, an inner peripheral surface of a shaft hole 101a of a housing 101 and a shaft inserted through the shaft hole 101a. A sealing device 100 (so-called oil seal) is provided to seal the annular gap 103 between the outer peripheral surface 102a of the base 102 and the sealing target fluid side O to prevent the leakage of the sealing fluid from the sealing target fluid side O to the anti-sealing target fluid side A. Have been.
[0003]
The sealing device 100 has an annular shape, and has a substantially L-shaped cross section having an axial portion 105a on the outer peripheral side and a radial portion 105b bent inward from one end of the axial portion 105a (the anti-sealing target fluid side A). And a fitting portion 106 and a seal portion 107 made of a rubber-like elastic body integrally formed so as to employ the periphery of the reinforcing ring 105.
[0004]
The seal portion 107 includes a main seal portion 107a extending from the radial portion 105b of the reinforcing ring 105 to the fluid side O to be sealed and in contact with the outer peripheral surface 102a of the shaft 102 as a sliding surface.
[0005]
In order to prevent the deformation and movement of the main seal portion 107a due to the pressure of the fluid to be sealed during operation and the movement of the shaft, a backup ring 108 for holding the posture of the main seal portion 107a is provided to prevent the main seal portion 107a from being sealed. It is provided in contact with the side surface of the target fluid side A.
[0006]
Reference numeral 109 denotes a spring for applying a tension to the main seal portion 107a.
[0007]
In the sealing device 100 configured as described above, the main seal portion 107a made of a rubber-like elastic body is used in combination with the backup ring 108 that holds the posture of the main seal portion 107a, so that the main seal portion 107a is used. To prevent damage and enable use under high pressure.
[0008]
[Problems to be solved by the invention]
In the prior art described above, the backup ring 108 is useful for reducing the protrusion gap b shown in FIG. 5A by following the backup ring even when relatively large eccentricity occurs.
[0009]
However, depending on the operating state of the actual machine, for example, when the shaft moves at high speed or when pressure is generated when the shaft moves to the anti-sealing target fluid side A, the gap between the backup ring and the shaft increases. There may be cases.
[0010]
When the shaft moves at a high speed, as shown in FIG. 5B, the behavior of the main seal portion 107a due to the frictional force between the shaft 102 and the main seal portion 107a (movement from the dotted line portion to the solid line portion) ), The backup ring 108 moves (moves from the dotted line part to the solid line part), causing a shift.
[0011]
In such a case, as shown in FIG. 5C, when the shaft 102 moves to the anti-sealing target fluid side A, a part of the main seal portion 107a protrudes into the gap between the backup ring 108 and the shaft 102. If the rubber sticks out of the gap between the backup ring 108 and the shaft 102, the rubber at the protruding portion may be dragged with the movement of the shaft 102 toward the fluid O to be sealed, and may be damaged. is there.
[0012]
Further, in the sealing device 100, the anti-sealing target fluid side A of the main seal portion 107 a pressed by the pressure from the sealing target fluid side O, that is, the contact portion between the main seal portion 107 a and the backup ring 108. In some cases, a contact surface pressure peak occurs in a portion in contact with the shaft 102.
[0013]
In operation, when the shaft 102 returns to the fluid side O to be sealed, the peak portion of the surface pressure scrapes out the fluid to be sealed out, which causes an increase in the amount of leakage. The sliding resistance increases due to the scraping of the fluid to be sealed, and there is a possibility that the abrasion of the main seal portion 107a increases.
[0014]
Here, the amount of leakage Q of the reciprocating sealing device is determined by the amount Up of the film of the fluid to be sealed on the shaft surface which is drawn out when the shaft moves from the fluid to be sealed O to the fluid side A to be sealed (forward stroke), and , The axis moves on the opposite side (from the anti-sealing target fluid side A to the sealing target fluid side O) (return stroke), and the difference from the amount Um to which the drawn-out sealing target fluid returns, that is,
Q = Up-Um
Is represented by
[0015]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the related art, and an object of the present invention is to provide a highly reliable sealing device that improves quality and extends life.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
A sealing device for sealing between two members which are coaxially and relatively movably assembled with each other,
A seal body extending toward the fluid to be sealed toward one of the two members, the seal body having a seal portion that slides on the one member,
A backup ring that is disposed between the seal body and the one member and supports the seal body,
The backup ring includes a protrusion protruding along at least a part of the seal portion.
[0017]
Therefore, since the seal portion can be supported by the protrusion, when one member moves during operation, the seal portion is dragged by the one member and protrudes between the backup ring and the one member. Can be prevented.
[0018]
Also, when the pressure of the fluid to be sealed is applied, the surface pressure of the seal portion against one member is increased by the pressure, thereby causing wear or causing the seal portion to be easily dragged by the one member and the backup ring. Although there is a possibility that the protrusion may protrude from one of the members, the provision of the projection allows the pressure of the fluid to be sealed to be received by the projection, so that good surface pressure can be maintained.
[0019]
Accordingly, it is possible to prevent the seal portion from being damaged due to the movement of one member in a state where the seal portion has protruded.
[0020]
The seal body may have a step formed on the one member side adjacent to a side of the seal part opposite to the fluid to be sealed, and the protrusion of the backup ring may be formed along the step. It is suitable.
[0021]
This makes it possible to suppress the behavior of the seal portion on the side opposite to the fluid to be sealed, and to stabilize the axial position of the backup ring as well as the radial behavior, thereby stabilizing the sealing performance. Can be achieved.
[0022]
It is also preferable that an axial groove is provided on the peripheral surface of the protrusion of the backup ring on the one member side.
[0023]
As a result, the fluid to be sealed can be positively held in the groove, so that good lubrication can be maintained, and the fluid to be sealed intervenes (holds) well on the lip sliding surface and the backup ring. In addition, wear of the seal portion and the backup ring can be suppressed, and the life of the sealing device can be extended.
[0024]
Here, the tip of the lip of the seal portion may have a substantially mountain-shaped cross section, and the protrusion may be provided so as to extend from the step portion and protrude along a slope forming the substantially mountain-shaped cross section of the seal portion. .
[0025]
Thereby, it is possible to more reliably prevent the seal portion from protruding between the backup ring and the one member.
[0026]
Also, as the slope that forms the substantially mountain-shaped cross section of the seal portion and the surface along the slope of the protrusion are closer to the one member, the protrusion can suppress the behavior of the seal portion, The part is less likely to be dragged by one member.
[0027]
Further, the protrusion is provided closer to the one member than the ring main body of the backup ring, that is, when one member is a shaft member, the protrusion is provided with a diameter smaller than the ring main body, and one member is provided. In the case of a housing having a shaft hole, the diameter of the housing may be larger than that of the ring body.
[0028]
Thus, the gap between the one member and the one member can be reduced, so that it is possible to more reliably prevent the seal portion from protruding between the backup ring and the one member.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively 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 thereto unless otherwise specified. Absent.
[0030]
FIG. 1A is a schematic cross-sectional view of a sealing device according to an embodiment of the present invention, and FIG. 1B is a diagram for explaining a main part of the sealing device.
[0031]
The sealing device 1 is an oil seal that seals an annular gap 4 between a shaft hole 2a of the housing 2 as the other member of the two members and an outer peripheral surface 3a of the shaft 3 as one member. It is provided to prevent leakage of the sealing target fluid from the fluid side O to the anti-sealing target fluid side A.
[0032]
The sealing device 1 has an annular shape, and has a fitting portion 7, a sealing portion 8, and a reinforcing ring 5 and a rubber-like elastic body integrally formed so as to cover the periphery of the reinforcing ring 5. There is provided a radial portion 9 connecting the fitting portion 7 and the seal portion 8.
[0033]
The reinforcing ring 5 has an axial portion 5a on the outer peripheral side, and a radial portion 5b that bends toward the inner diameter side from one end (the anti-sealing target fluid side A) of the axial portion 5a, and retains the annular shape of the sealing device 1. Is what you do.
[0034]
The axial portion 5 a generates a predetermined fitting force in the fitting portion 7 when mounted on the housing 2, and the radial portion 5 b includes a support portion that supports the seal portion 8 and the radial portion 9. Become.
[0035]
The reinforcing ring 5 is generally formed by press-forming a metal plate such as SPCC, but may be formed by an aluminum die-cast member or a resin member having a certain degree of rigidity. Is also possible.
[0036]
The seal portion 8 includes a main lip portion 8a extending from the radial portion 9 of the rubber-like elastic body to the inner fluid side O toward the fluid O to be sealed. The lip tip of the main lip portion 8a has a slope 8b extending from the root portion 8c, which is provided continuously to the inner diameter side end portion of the radial portion 9, on the inner diameter side and extending toward the fluid O to be sealed. Is a substantially mountain-shaped cross-section that is folded back to the fluid side O to be sealed on the outer diameter side at the position.
[0037]
In addition, in order to exhibit good sealing performance, each slope having a substantially mountain-shaped cross section at the tip of the lip is set to have a predetermined angle with respect to the shaft 3. For this purpose, in the seal portion 8, a step 8d for adjusting the angle of the slope 8b with respect to the shaft 3 is provided at the transition from the base 8c to the slope 8b.
[0038]
In order to prevent the deformation and movement of the main lip portion 8a due to the pressure of the fluid sealed during operation and the reciprocating motion of the shaft, the backup ring 10 holding the posture of the main lip portion 8a is mounted on the main lip portion 8a. It is provided in contact with the side surface of the fluid side A to be sealed and the radial portion 5 b of the reinforcing ring 5. The backup ring 10 is made of a resin material harder than the rubber-like elastic body.
[0039]
The backup ring 10 as a characteristic configuration of the present embodiment projects from the ring main body 10a and the inner peripheral side of the side surface (radial surface) on the main lip portion 8a side of the ring main body 10a to the fluid side O to be sealed in the axial direction. And a projection 10b.
[0040]
The inner diameter of the projection 10b is provided to be smaller than the diameter of the ring main body 10a.
[0041]
The shape between the tip of the projection-side portion 10b on the fluid side O to be sealed axially and the tip of the fluid-side O on the outer periphery side of the ring main body 10a constitutes a step portion 10c. It is formed in a shape along the step 8d provided in the seal portion 8, that is, in a substantially concave shape in cross section as shown in FIG. It is provided in.
[0042]
Therefore, by providing the step portion 10c, the protrusion portion 10b is formed.
[0043]
Here, the stepped portion 10c does not need to be formed completely along the stepped portion 8d, and may be, for example, stepped or wavy.
[0044]
The protruding portion 10b has a shape along the slope 8b constituting the lip tip of the main lip portion 8a, and supports the main lip portion 8a.
[0045]
The backup ring 10 may be one having no cut portion (cut) in the circumferential direction (endless shape) or one having a cut portion.
[0046]
Reference numeral 11 denotes a spring for applying a tension to the main lip 8a.
[0047]
In the sealing device 1 configured as described above, the main lip portion 8a can be prevented from protruding between the backup ring 10 and the shaft 3. Therefore, it is possible to prevent the main lip portion 8a from being damaged due to the movement of the shaft with the rubber of the main lip portion 8a protruding.
[0048]
In addition, by providing the projection 10b with a reduced diameter from the backup ring main body 10a, the gap with the shaft 3 is reduced, and deformation in the direction in which the shaft 3 is closely contacted is facilitated. The protrusion between the shaft 10 and the shaft 3 can be more reliably prevented.
[0049]
Further, the shape between the tip of the fluid side O to be sealed in the axial direction of the projection 10b and the tip of the fluid side O to be sealed in the axial direction on the outer peripheral side of the backup ring main body 10a is shaped along the step 8d of the seal portion 8. By having a substantially concave cross-sectional shape, the behavior of the main lip 8a toward the anti-sealing target fluid side A can be suppressed, and the position of the backup ring 10 in the axial direction can be stabilized. Also, the behavior in the radial direction can be stabilized, and the sealing performance can be stabilized.
[0050]
In addition, by extending the inner peripheral side from the root portion 8c to the fluid side O to be sealed in the axial direction and providing the protruding portion 10b along the slope 8b constituting the lip tip of the main lip portion 8a, during operation, When the shaft 3 moves to the anti-sealing target fluid side A, the behavior of the main lip portion 8a dragged by the shaft 3 toward the anti-sealing target fluid side A can be suppressed (supported), and the main lip portion 8a is backed up. Protruding between the ring 10 and the shaft 3 can be reliably prevented. As the inclined surface 8b and the surface along the inclined surface 8b of the protrusion 10b are closer to the axis 3, the protrusion 10b can suppress the behavior of the main lip 8a.
[0051]
Since the pressure of the fluid to be sealed from the fluid side O to be sealed is applied to the radial portion 9, the radial portion 9 can be compressed and the radial biasing force generated by the projection 10 b can be received by the projection 10 b. Excessive increase in surface pressure of the portion 8a can be prevented.
[0052]
The rigidity of the projection 10b can be adjusted by adjusting the thickness and shape of the projection 10b according to the specifications of the device.
[0053]
When the rigidity of the projection 10b is set to be large, when the shaft 3 moves to the anti-sealing target fluid side A during operation, the behavior of the main lip portion 8a dragged by the shaft 3 toward the anti-sealing target fluid side A Can be suppressed (supported), and the main lip portion 8a can be prevented from protruding between the backup ring 10 and the shaft 3.
[0054]
When the rigidity of the projection 10b is set to be small, the response to pressure can be improved.
[0055]
Therefore, during operation, when the shaft 3 moves to the anti-sealing target fluid side A, the behavior of the projection 10b accompanying the behavior of the main lip portion 8a toward the anti-sealing target fluid side A occurs. As a result, the projection 10b moves in response to the movement of the main lip 8a, so that the main lip 8a is drawn to the shaft 3 with the backup ring as a fulcrum, and protrudes between the backup ring 10 and the shaft 3. Can be prevented.
[0056]
Further, by making the tip of the protrusion 10b sharp (edge-like), the area of contact with the slope 8b can be increased, and the gap with the shaft 3 can be reduced. The protrusion prevention effect is obtained.
[0057]
In order to improve the strength of the projection 10b, the tip of the projection 10b may be chamfered to have an R shape.
[0058]
The surface pressure distribution of the sealing device 1 configured as described above will be described.
[0059]
FIG. 2A is a diagram for explaining the surface pressure distribution of the lip portion of the sealing device according to the present embodiment, and FIG. 2B is a diagram illustrating the surface pressure distribution of the lip portion of the conventional sealing device. It is a figure for explaining.
[0060]
As shown in the figure, in the related art, a peak is generated at a contact portion a between the main lip portion 107a and the backup ring 108 and in contact with the shaft 3, but in the present embodiment, the peak is generated. Since the rubber does not enter between the ring 10 and the shaft 3, the peak of the surface pressure does not occur at this portion, and the peak of the surface pressure also decreases.
[0061]
Therefore, the amount of leakage can be reduced.
[0062]
Also, since a good surface pressure can be maintained even during operation, the fluid to be sealed is not scraped out by the portion a where the surface pressure peaks as in the related art, so that the sliding resistance does not increase, The fluid to be sealed is satisfactorily interposed (held) on the lip sliding surface, so that the wear of the main lip portion 8a can be suppressed, and the life of the sealing device can be extended.
[0063]
FIGS. 3A and 3B show a backup ring 20 as a modified example of the backup ring 10, in which FIG. 3A is a schematic sectional view, and FIG. 3B is a schematic top view of FIG.
[0064]
The backup ring 20 is provided with an axial groove 20d on the inner periphery of the backup ring with respect to the backup ring 10.
[0065]
The backup ring 20 includes a ring main body 20a, and a projection 20b protruding from the inner peripheral side of the side surface (radial surface) of the ring main body 20a on the side of the main lip 8a toward the fluid O to be sealed in the axial direction.
[0066]
The shape between the tip of the projection-side portion 20b on the fluid side O to be sealed in the axial direction and the tip of the ring-side body 20a on the fluid side O in the axial direction to be sealed constitutes a stepped portion 20c, and the main lip portion 8a Has a substantially concave cross-section so as to receive the behavior toward the fluid side A to be sealed.
[0067]
The grooves 20d are provided on the inner peripheral surface of the backup ring 20 at substantially equal intervals. Here, the groove 20d only needs to be provided at least on the inner peripheral side of the protrusion 20b. Further, the number and size of the grooves may be appropriately set, and may not be provided at equal intervals as shown in the figure.
[0068]
As a result, the fluid to be sealed can be positively held in the groove 20d, so that good lubrication can be maintained, and the fluid to be sealed intervenes (holds) well on the lip sliding surface and the backup ring 10. ), The wear of the main lip portion 8a and the backup ring 10 can be suppressed, and the life of the sealing device can be extended.
[0069]
【The invention's effect】
As described above, according to the present invention, the breakage of the seal portion can be prevented, so that the quality can be improved and the life can be extended.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a sealing device according to an embodiment of the present invention.
FIG. 2A is a diagram for explaining a surface pressure distribution of a sealing device according to an embodiment, and FIG. 2B is a diagram for explaining a surface pressure distribution of a sealing device according to a conventional technique. FIG.
3A and 3B are schematic cross-sectional views showing a modification of the seal ring, where FIG. 3A is a schematic cross-sectional view and FIG. 3B is a schematic top view of FIG.
FIG. 4 is a schematic sectional view of a sealing device according to the related art.
FIG. 5 is an explanatory view of a problem of the sealing device according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Housing 2a Shaft hole 3 Shaft 3a Outer peripheral surface 4 Annular gap 5 Reinforcement ring 5a Axial portion 5b Radial portion 7 Fitting portion 8 Seal portion 8a Main lip portion 8b Slope 8c Root portion 8d Step portion 9 Radial portion Reference Signs List 10 backup ring 10a ring main body 10b projection 10c step 11 spring

Claims (3)

A sealing device for sealing between two members which are coaxially and relatively movably assembled with each other,
A seal body extending toward the fluid to be sealed toward one of the two members, the seal body having a seal portion that slides on the one member,
A backup ring that is disposed between the seal body and the one member and supports the seal body,
The sealing device, wherein the backup ring includes a protrusion protruding along at least a part of the seal portion. In the seal body, a step portion is formed on the one member side adjacent to the anti-sealing target fluid side of the seal portion, and the protrusion of the backup ring is formed along the step portion. The sealing device according to claim 1, characterized in that: The sealing device according to claim 1, wherein an axial groove is provided on a peripheral surface of the protrusion of the backup ring on the one member side.

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