JP2017089785A - Seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal capable of adjusting an internal pressure.SOLUTION: This invention relates to a seal installed between a shaft and a housing that are rotated to each other so as to seal against an inside part of the housing and the surrounding atmosphere. This seal comprises a metal ring 11 fixed to the housing, a seal main body 10 having a lip part 12 applied to this metal ring and an auxiliary seal 20 fixed to the metal ring of the seal main body. The lip part has a main lip 13 facing to the surrounding atmosphere and slidably contacting with the shaft and an auxiliary lip 14 facing against the inside part of the housing and slidably contacting with the shaft. The auxiliary seal has a vent trip facing against the surrounding atmosphere and slidably contacting to the shaft and releasing it as a pressure at inside part of the housing is increased to cause the pressure to be released into an annular space R between the seal main body and the auxiliary seal. The seal main body has a first vent mechanism capable of releasing pressure in the annular space to the surrounding atmosphere and the auxiliary seal has a second vent mechanism capable of releasing the pressure in the annular space to the inside part of the housing.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sealing device. More specifically, the present invention relates to a sealing device that is used in, for example, a power steering device of an automobile and functions as a dust seal that prevents muddy water, dust, and the like from entering the device from the outside.

  As shown in FIG. 5, the power steering device of an automobile is a type in which the device is sealed with a bellows 50 or a dust seal 51 as shown in FIG. 5 in order to prevent intrusion of muddy water, dust, foreign matter, etc. from the outside. There are things. As shown in FIG. 6, the dust seal 51 is mounted in an annular space S formed between a steering pinion shaft shaft 52 that rotates relative to each other and a housing 53 that is disposed concentrically with the shaft 52. The side (lower side in FIG. 6) and the atmosphere side (upper side in FIG. 6) are sealed. The dust seal 51 includes a metal ring 54 fixed to the housing 53 and a lip portion 55 attached to the metal ring 54.

  In such a type of power steering device P, the internal pressure changes due to a temperature change due to repeated rapid acceleration / deceleration or a change in atmospheric pressure due to an altitude difference, and a large negative pressure such as −30 kPa may be generated in the device. .

  When a large negative pressure is generated, there is a possibility that the bellows 50 sealing a relatively large space is deformed by the negative pressure, causing a problem that a crack is formed and is broken.

  This invention is made | formed in view of such a situation, and it aims at providing the sealing device which can adjust an internal pressure.

A sealing device according to an aspect of the present invention is a sealing device that is mounted in an annular space formed between a shaft and a housing that rotate relative to each other, and seals the housing inner side and the atmosphere side,
A seal body including a metal ring fixed to the housing, and a lip portion attached to the metal ring;
An auxiliary seal fixed to the metal ring of the seal body,
The lip portion has a main lip that is in sliding contact with the shaft facing the atmosphere side, and an auxiliary lip that is in sliding contact with the shaft facing the inner side of the housing,
The auxiliary seal faces the atmosphere and is in sliding contact with the shaft, and has a bent trip that opens when the pressure inside the housing rises and releases the pressure to the annular space between the seal body and the auxiliary seal. And
The seal body has a first vent mechanism that allows the pressure in the annular space to escape to the atmosphere side,
The auxiliary seal has a second vent mechanism that can release the pressure in the annular space to the inside of the housing.

  According to the above invention, the internal pressure can be adjusted.

It is a perspective explanatory view of an example of a power steering device to which a sealing device of the present invention is applied. It is a section explanatory view of the sealing device concerning one embodiment of the present invention. It is the fragmentary top view which looked at the sealing device shown by FIG. 2 from the atmosphere side. It is a section explanatory view of the sealing device concerning other embodiments of the present invention. It is a perspective explanatory view of an example of the conventional power steering device. It is sectional explanatory drawing of an example of the conventional sealing device.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.
A sealing device according to one embodiment of the present invention includes:
(1) A sealing device that is mounted in an annular space formed between a shaft and a housing that rotate relative to each other and seals the inside of the housing and the atmosphere.
A seal body including a metal ring fixed to the housing, and a lip portion attached to the metal ring;
An auxiliary seal fixed to the metal ring of the seal body,
The lip portion has a main lip that is in sliding contact with the shaft facing the atmosphere side, and an auxiliary lip that is in sliding contact with the shaft facing the inner side of the housing,
The auxiliary seal faces the atmosphere and is in sliding contact with the shaft, and has a bent trip that opens when the pressure inside the housing rises and releases the pressure to the annular space between the seal body and the auxiliary seal. And
The seal body has a first vent mechanism that allows the pressure in the annular space to escape to the atmosphere side,
The auxiliary seal has a second vent mechanism that can release the pressure in the annular space to the inside of the housing.

  In the sealing device according to this aspect, when the air pressure on the housing inner side, that is, the inner side of the device to which the sealing device is mounted, increases to a positive pressure exceeding a predetermined value, the auxiliary seal vent trip is deformed to the atmosphere side. Then, the seal by the bent trip is opened, and the increased pressure is released to the annular space between the seal body and the auxiliary seal. And if the pressure in this annular space becomes high, the 1st vent mechanism of a seal body will function this time, and the pressure in annular space will be released to the atmosphere side. Therefore, it is possible to prevent the pressure in the apparatus from becoming higher than a certain level. On the other hand, when the pressure in the apparatus drops to a negative pressure exceeding a predetermined value, the second vent mechanism of the auxiliary seal functions to release the pressure in the annular space to the inside of the housing. Therefore, it is possible to prevent the pressure in the apparatus from becoming lower than a certain level. As described above, in the sealing device according to this aspect, the seal main body and the auxiliary seal having the bent trip are combined, and each of the seal main body and the auxiliary seal is provided with a vent mechanism, so that the inside of the device to which the sealing device is attached. It is possible to adjust or control the pressure.

(2) In the sealing device according to (1), the first vent mechanism includes a first slit formed in the seal body, and the second vent mechanism includes a second slit formed in the auxiliary seal. Is preferred. In this case, the vent mechanism can be realized by a simple configuration called a slit.

(3) In the sealing device of (2), the first slit is formed on a convex portion provided on the atmosphere-side surface of the seal body, and the second slit is formed on the housing-inside surface of the auxiliary seal. It is preferable to be formed on the provided convex part. In this case, the slit can be formed using the convex portion as a mark, and the slit can be formed easily and reliably.

(4) In the sealing device of the above (1) to (3), the sealing device can be a sealing device used for a steering pinion shaft of an automobile.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of a sealing device of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

FIG. 1 is a perspective explanatory view of an example of a power steering device to which a sealing device of the present invention is applied, and FIG. 2 is a cross-sectional explanatory view of the sealing device 1 according to an embodiment of the present invention.
The power steering device P is a mechanism that assists the driver's steering, and is a rack and pinion type power steering device. Tie rods 3a and 3b are connected to both ends of the rack and pinion unit 2, and bellows 4a and 4b for preventing muddy water, dust, foreign matter and the like from entering the inside are disposed at the connecting portion. Yes. A steering pinion shaft 5 connected to a steering shaft (not shown) is disposed concentrically with the housing 9 in a cylindrical housing 7 integrally formed with the casing 6 of the rack and pinion unit 2. .

  The sealing device 1 according to this embodiment is mounted in an annular space S formed between a steering pinion shaft 5 and a housing 7 that rotate relative to each other. As with the bellows 4a and 4b, the sealing device 1 is used to prevent intrusion of muddy water, dust, foreign matter, and the like from the outside, and the housing inner side (the lower side in FIG. 2) and the atmospheric side ( The upper side in FIG. 2 is sealed.

  The sealing device 1 includes a seal body 10 and an auxiliary seal 20. The seal body 10 includes a metal ring 11 fixed to the housing 7 and a lip portion 12 attached to the metal ring 11. The auxiliary seal 20 includes a metal ring 21 fixed to the inner peripheral surface 11 a of the metal ring 11 of the seal body 10 and a lip portion 22 attached to the metal ring 21. Unlike a conventional sealing device (such as the dust seal 51 of FIG. 6), the sealing device 1 is combined with the seal body 10 and the auxiliary seal 20 to exhibit a sealing function and a pressure adjusting function described later.

  The lip portion 12 of the seal body 10 has a main lip 13 that is in sliding contact with the outer peripheral surface of the steering pinion shaft 5 facing the atmosphere side, and an auxiliary lip 14 that is in sliding contact with the outer peripheral surface of the steering pinion shaft 5 facing the inner side of the housing. Have.

  A short columnar convex portion 15 is formed integrally with the lip portion 12 on the atmosphere-side surface 12 a of the lip portion 12 of the seal body 10. The metal ring 11 is composed of a cylindrical portion 16 fixed to the housing 7 and a disk portion 17 extending radially inward from the atmospheric end of the cylindrical portion 16, and the position of the convex portion 15. A circular hole 18 is formed in the disk portion 17 corresponding to. The lip portion 12 is also formed on the inner peripheral surface 18 a of the round hole 18 and the peripheral portion 17 a of the round hole 18 among the back surface of the disc portion 17. In the lip portion 12 located in the round hole 18, a recess 19 having a short cylindrical shape in the lower part and a conical shape in the upper part is formed in FIG. The tip of the conical recess 19 reaches a position substantially equal to the surface 12a on the atmosphere side of the lip 12 in the vertical direction.

  As shown in FIG. 3, a slit 30 that is a first vent mechanism is formed in the vicinity of the center of the convex portion 15 along the radial direction. The slit 30 has a narrow width and is normally substantially closed by the elastic force of the lip portion 12 made of an elastic material such as rubber.

  The lip portion 22 of the auxiliary seal 20 has a bent trip 23 that faces the atmosphere side and comes into sliding contact with the steering pinion shaft 5. The ben trip 23 is normally in sliding contact with the outer peripheral surface of the steering shaft 5, but when the pressure inside the housing rises, it tilts in the direction indicated by the arrow A in FIG. 2 to open the seal. Thereby, the pressure inside the housing is released to the annular space R between the seal body 10 and the auxiliary seal 20.

  A short cylindrical projection 24 is formed integrally with the lip 22 on the housing-side surface 22 a of the lip 22 of the auxiliary seal 20. The metal ring 22 includes a cylindrical portion 25 that is fixed to the inner peripheral surface of the cylindrical portion 16 of the metal ring 11, and a disc portion 26 that extends radially inward from the housing-side end of the cylindrical portion 16. A round hole 27 is formed in the disc portion 26 corresponding to the position of the convex portion 24. The lip portion 22 is also formed on the peripheral portion of the round hole 27 in the inner peripheral surface 27 a of the round hole 27 and the back surface (the surface on the annular space S side) of the disc portion 26. The lip portion 22 located in the round hole 27 is formed with a recess 28 having a short cylindrical shape in the upper part and a conical shape in the lower part in FIG. The tip of the conical recess 28 reaches a position substantially equal to the housing-side surface 22a of the lip 22 in the vertical direction.

  A slit 31 that is a second vent mechanism is formed in the vicinity of the center of the convex portion 24 along the radial direction in the same manner as the slit 30 shown in FIG. The slit 31 has a narrow width and is normally substantially closed by the elastic force of the lip portion 22 made of an elastic material such as rubber.

Next, the pressure adjustment function of the sealing device 1 according to the present embodiment will be described.
The sealing device 1 functions as a so-called dust seal when the pressure in the power steering device P does not vary greatly, and prevents muddy water, dust, foreign matter and the like from entering the device.

  However, when the internal pressure changes due to a temperature change due to repeated rapid acceleration / deceleration or a change in atmospheric pressure due to an altitude difference, and the pressure in the apparatus becomes a positive pressure exceeding a predetermined value (for example, 10 kPa), the auxiliary seal 20 The bent trip 23 is deformed to the atmosphere side, the seal by the bent trip 23 is opened, and the increased pressure is released to the annular space R between the seal body 10 and the auxiliary seal 20. When the pressure in the annular space R increases, the slit 30 of the seal body 10 expands this time, and the pressure in the annular space R is released to the atmosphere side (see arrow B in FIG. 2). Therefore, it is possible to prevent the pressure in the power steering device P from becoming higher than a certain level. On the other hand, when the pressure in the power steering device P decreases to a negative pressure exceeding a predetermined value (for example, −10 kPa), the slit 31 of the auxiliary seal 20 expands, and the pressure in the annular space R is released to the inside of the housing ( (See arrow C in FIG. 2). Therefore, the pressure in the power steering device P can be prevented from becoming lower than a certain level. As described above, in the sealing device 1 according to the present embodiment, the seal body 10 and the auxiliary seal 20 having the bent trip 23 are combined, and the seal body 10 and the auxiliary seal 20 have slits 30 and 31 as vent mechanisms, respectively. By forming, the pressure in the power steering device P to which the sealing device 1 is attached can be adjusted or controlled. As a result, it is possible to prevent problems such as deformation of the bellows 4a and 4b due to negative pressure.

  FIG. 4 is a cross-sectional explanatory view of a sealing device 40 according to another embodiment of the present invention. Most of the configuration of the sealing device 40 is the same as the configuration of the sealing device 1 described above. Accordingly, common elements or members are denoted by the same reference numerals, and description of the common elements or members is omitted for simplicity. The sealing device 40 differs from the sealing device 1 shown in FIG. 2 in that the sealing device 40 has a height H2 (in the axial direction of the steering pinion shaft 5) of the sealing device 40 in order to increase the volume of the annular space R. And the fixing position of the auxiliary seal 41 is moved to the distal end side (the lower side in FIG. 4) of the cylindrical portion 44 of the metal ring 43 of the seal body 42. It is a point. In the sealing device 1, the tip of the cylindrical portion 25 of the metal ring 21 of the auxiliary seal 20 is inserted deeply until it contacts the disc portion 17 of the metal ring 11 of the seal body 10. In the sealing device 40, the height (the vertical size in FIG. 4) of the cylindrical portion 46 of the metal ring 45 of the auxiliary seal 41 is lower than the height of the cylindrical portion 25 of the metal ring 21 of the auxiliary seal 20. The tip of 46 is not inserted deeply until it abuts on the disk portion 47 of the metal ring 43 of the seal body 42.

  Also in the sealing device 40, the sealing function and the pressure adjusting function can be exhibited in the same manner as the sealing device 1, and since the volume of the annular space R is larger in the sealing device 40 than in the sealing device 1, the pressure change is larger. Can respond.

  Since the sealing device 1 and the sealing device 40 are stored and transported in a state where they are stacked in the vertical direction, the auxiliary lip 41 of the sealing device 40 is also used in the sealing device 40 so that the main lip 13 does not interfere with other elements during stacking. It is desirable to ensure a certain height H3 below.

[Other variations]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.
For example, in the above-described embodiment, a straight slit is used as a vent mechanism in a plan view, but other shapes, for example, a cross-shaped slit in a plan view may be used.

  In the embodiment described above, the number of slits is one, but two or more slits may be formed.

1: Sealing device 2: Rack & pinion unit 3a, 3b: Tie rod
4a, 4b: Bellows 5: Steering pinion shaft 6: Casing 7: Housing 10: Seal body 11: Metal ring 12: Lip part 13: Main lip 14: Auxiliary lip 15: Convex part 20: Auxiliary seal 21: Metal ring 22: Lip part 23: Ben trip 24: Convex part 30: Slit 31: Slit 40: Sealing device 41: Auxiliary seal 42: Seal main body 43: Metal ring P: Power steering device S: Annular space R: Annular space

Claims (4)

A sealing device that is mounted in an annular space formed between a shaft and a housing that rotate relative to each other and seals the housing inner side and the atmosphere side,
A seal body including a metal ring fixed to the housing, and a lip portion attached to the metal ring;
An auxiliary seal fixed to the metal ring of the seal body,
The lip portion has a main lip that is in sliding contact with the shaft facing the atmosphere side, and an auxiliary lip that is in sliding contact with the shaft facing the inner side of the housing,
The auxiliary seal faces the atmosphere and is in sliding contact with the shaft, and has a bent trip that opens when the pressure inside the housing rises and releases the pressure to the annular space between the seal body and the auxiliary seal. And
The seal body has a first vent mechanism that allows the pressure in the annular space to escape to the atmosphere side,
The sealing device according to claim 1, wherein the auxiliary seal has a second vent mechanism that allows the pressure in the annular space to escape to the inside of the housing.   2. The sealing device according to claim 1, wherein the first vent mechanism includes a first slit formed in the seal body, and the second vent mechanism includes a second slit formed in the auxiliary seal.   The said 1st slit is formed in the convex part provided in the atmosphere side surface of the said seal | sticker main body, The said 2nd slit is formed in the convex part provided in the housing inner side surface of the said auxiliary | assistant seal. 3. The sealing device according to 2.   The said sealing apparatus is a sealing apparatus used for the steering pinion shaft of a motor vehicle, The sealing apparatus of any one of Claims 1-3.

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