JP5625247B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device having a thin bellows part.

  Conventionally, a sealing device for sealing an annular gap between a housing and a shaft is known. As a sealing device used in a device in which the shaft is greatly decentered with respect to the housing, the seal portion is provided on the inner peripheral end side of the thin bellows portion so that the seal portion in contact with the shaft follows the shaft eccentricity. A known sealing device is known (see Patent Documents 1 to 3).

  Such a conventional sealing device will be described with reference to FIGS. 4 is a part of a schematic cross-sectional view of the sealing device according to Conventional Example 1, and FIG. 5 is a part of the schematic cross-sectional view of the sealing device according to Conventional Example 2.

  A sealing device 400 according to Conventional Example 1 shown in FIG. 4 includes a fixing portion 410 that is fixed to the inner peripheral side of the shaft hole of the housing, and a thin bellows portion 420 that extends in a bellows shape from the fixing portion 410 toward the shaft surface. , And a seal portion 430 provided on the inner peripheral end side of the bellows portion 420. The seal portion 430 includes a bumper portion 431 and a lip portion 432 configured to be slidable with respect to the outer peripheral surface of the shaft.

  A sealing device 450 according to Conventional Example 2 shown in FIG. 5 has the same basic configuration, and includes a fixing portion 460, a bellows portion 470, and a seal portion 480. The seal portion 480 includes a bumper portion 481 and a lip portion 482. The bellows 420 in the sealing device 400 according to the conventional example 1 and the bellows 470 in the sealing device 450 according to the conventional example 2 have different bellows shapes (directions). It is the same in the point provided. In the case of the sealing device 400 according to Conventional Example 1, a reinforcing ring 431 a that suppresses deformation of the bumper portion 431 is provided inside the bumper portion 431.

  Here, in FIG. 5, the housing 500 and the shaft 600 are indicated by dotted lines. The shaft 600 rotates as indicated by an arrow A in the figure and swings (is eccentric with respect to the housing 500) as indicated by an arrow B in the figure. In the sealing devices 400 and 450 according to the conventional examples 1 and 2, even if the shaft 600 is decentered, the bellows portions 420 and 470 are deformed while the bumper portions 431 and 481 remain in close contact with the shaft 600, so that the lip The portions 432 and 482 are in close contact with the outer peripheral surface of the shaft 600, and the sealing performance is maintained.

  However, when the eccentricity and rotation of the shaft 600 are repeated at the same time, there is a problem that the bellows 420 and 470 are cracked or split. This will be described with reference to FIG. FIG. 6 is a schematic view of the sealing device viewed in the axial direction when the shaft is eccentric and rotating. In FIG. 6, 400P indicates the position of the inner peripheral end of the lip portion, 400Q indicates the position of the outer peripheral end of the fixed portion, and 400R schematically shows the deformation of the bellows portion.

  In a state where the shaft is eccentric and rotated, the inner peripheral end 400P of the lip portion moves in a direction eccentric with respect to the outer peripheral end 400Q of the fixed portion as the shaft moves in the eccentric direction (see arrow B in the figure). ), And a force (torque) in the direction of rotation (see arrow A in the figure) is applied as the shaft rotates.

  As a result, the bellows portion is twisted and stress is concentrated in a part (X portion in the figure). Therefore, when the eccentricity and rotation of the shaft are repeated at the same time, the stress concentrated state is repeated, and cracking and tearing may occur.

  Patent Document 1 discloses a technique in which an annular convex portion (protrusion) is provided on the entire bellows portion in order to increase the durability of the bellows portion. However, in such a technique, the rigidity of the entire bellows portion is increased, and the eccentricity following property that is the original function of the bellows portion is adversely affected.

  Patent Document 2 discloses a technique in which a convex portion (reinforcing portion) extending in the axial direction is provided in the bellows portion in order to prevent the bellows portion from being turned when the shaft is inserted. However, in this technique, since the convex portion is configured to extend in the axial direction, the convex portion is not very resistant to the rotational force (torque) acting on the bellows portion. Therefore, the convex part in the technique disclosed in Patent Document 2 hardly exhibits the function of relieving stress concentration in the bellows part when a rotational force acts on the bellows part.

JP 2001-32946 A Utility Model Registration No. 2585626 Japanese Utility Model Publication No. 6-84068

  An object of the present invention is to provide a sealing device that can alleviate stress concentration on the bellows portion when the shaft is eccentric and rotates.

  The present invention employs the following means in order to solve the above problems.

That is, the sealing device of the present invention is
A housing having a shaft hole, and being inserted into the shaft hole and rotating and eccentric with respect to the housing (in addition to the case where the housing is stationary and the shaft is moving, the case where the shaft is stationary and the housing is moving and both are moving) A sealing device for sealing an annular gap between the shaft and the shaft configured to include:
A fixing portion fixed to the inner peripheral side of the shaft hole of the housing;
A thin bellows portion extending in a bellows shape from the fixed portion toward the shaft surface;
A seal portion which is provided on the inner peripheral end side of the bellows portion and slidably contacts the outer peripheral surface of the shaft;
A sealing device comprising:
The convex portion extending in the circumferential direction (which does not mean a complete circumferential direction (a direction that coincides with the concentric circle of the shaft)) that increases the rigidity of the bellows portion is the innermost portion in the bellows portion. It is provided only on the surface of the peripheral abdomen.

  According to the present invention, since the convex portion extending in the circumferential direction is provided on the bellows portion, when the rotational force acts on the bellows portion, the convex portion becomes a resistance force, and stress concentration on the bellows portion is alleviated. can do. And since this convex part is provided only in the surface of the bellows part of the innermost peripheral side in a bellows part, the rigidity of the whole bellows part increases compared with the case where such a convex part is provided in the whole bellows part. There is no end to it. Accordingly, it is possible to suppress a decrease in the eccentric followability. Therefore, the original function of the bellows part can be sufficiently exhibited. Further, among the plurality of bellows in the bellows, the amount of distortion increases when a rotational force is applied to the bellows, and a convex portion is provided on the innermost abdomen where stress tends to concentrate. It is possible to effectively suppress stress concentration on the surface.

  Moreover, the said convex part is good to be provided so that it may incline with respect to the concentric circle of an axis | shaft so that it may extend in the circumferential direction and an axial direction.

  If comprised in this way, a convex part will become resistance force not only with respect to the rotational force which acts on a bellows part but with respect to the force which acts so that it may turn in an axial direction. Therefore, the turning of the bellows portion can be suppressed.

  As described above, according to the present invention, stress concentration on the bellows portion can be reduced when the shaft is eccentric and rotates.

It is a partially broken perspective view of the sealing device concerning Example 1 of the present invention. It is a partially broken perspective view of the sealing device concerning Example 2 of the present invention. It is a partially broken perspective view of the sealing device concerning Example 3 of the present invention. It is a part of typical sectional drawing of the sealing device which concerns on the prior art example 1. FIG. It is a part of typical sectional drawing of the sealing device which concerns on the prior art example 2. FIG. It is the schematic diagram which looked at the sealing device in the axial direction when the shaft is eccentric and rotating.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail 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. .

  In the following embodiments, a steering dust seal will be described as an example of a sealing device. The steering seal seals an annular gap between a housing having a shaft hole and a shaft configured to be inserted through the shaft hole, as in the conventional examples 1 and 2. Then, like the conventional examples 1 and 2, the shaft rotates relative to the housing and swings (eccentric relative to the housing). As described above, the housing and the shaft are the same as those in the conventional example, and therefore the housing and the shaft are omitted in the drawings in the following embodiments. In each figure in the following embodiments, when the sealing device is used as a steering dust seal, the upper side of the sealing device is the engine room side and the lower side is the driver's seat side.

Example 1
With reference to FIG. 1, the sealing apparatus which concerns on Example 1 of this invention is demonstrated.

<Overall configuration of sealing device>
The sealing device 100 according to the present embodiment includes a fixing portion 110 that is fixed to the inner peripheral side of the shaft hole of the housing, a thin bellows portion 120 that extends in a bellows shape from the fixing portion 110 toward the shaft surface, and a bellows portion. 120 and a seal portion 130 provided on the inner peripheral end side. The seal portion 130 includes a bumper portion 131 and a lip portion 132 configured to be slidable with respect to the outer peripheral surface of the shaft.

The bumper portion 131 is configured to be thick so as to have high rigidity, and does not deform so much even when the shaft moves (rotates or decenters). Thereby, the thin lip part 132 is not deformed so much and is in contact with the shaft surface in a stable state. When the shaft is eccentric, the bellows portion 120 is deformed without the bumper portion 131 itself being deformed while the bumper portion 131 remains in close contact with the shaft. At this time, as described above, since the lip portion 132 is also in contact with the shaft surface in a stable state, the sealing performance is maintained.

<Details of bellows>
The bellows unit 120 will be described in more detail. The bellows portion 120 is provided in order to exhibit an eccentric tracking function so as to maintain the sealing performance by the seal portion 130 even if the shaft is eccentric. Therefore, the bellows portion 120 is configured to be thin and extend in a bellows shape toward the shaft surface. Therefore, not only does it deform easily in the radial direction, but it also has the property of being easily deformed with low rigidity in the circumferential direction. If the rigidity is low with respect to the circumferential direction, as described in the conventional example, if the shaft is in an eccentric and rotated state, a problem of cracking or tearing due to twisting of the bellows portion 120 may occur.

  Therefore, in the sealing device 100 according to the present embodiment, the annular convex portions 121 a and 121 b that increase the rigidity of the bellows portion 120 are provided only on the innermost abdominal portion 121 in the bellows portion 120. These convex portions 121a and 121b are provided on the inner peripheral side and the outer peripheral side of the abdomen 121, respectively, at positions separated in the axial direction (different end portions in the axial direction). Moreover, these convex parts 121a and 121b are provided concentrically with the shaft. Further, these convex portions 121 a and 121 b are provided integrally with the belly portion 121 of the bellows portion 120. That is, these convex parts 121a and 121b are integrally formed on the surface of the belly part 121 of the bellows part 120 by molding.

<Excellent point of sealing device according to this embodiment>
According to the sealing device 100 according to the present embodiment, the bellows portion 120 is provided with annular convex portions 121a and 121b (convex portions 121a and 121b concentric with the shaft) extending in the circumferential direction. Therefore, when a rotational force acts on the bellows portion 120, the convex portions 121a and 121b become resistance forces, and stress concentration on the bellows portion 120 can be reduced.

  The convex portions 121 a and 121 b are provided only on the surface of the innermost abdominal portion 121 in the bellows portion 120. Therefore, the rigidity of the entire bellows portion 120 does not increase as compared with the case where such a convex portion is provided on the entire bellows portion. Thereby, the fall of eccentric followability can be suppressed. Therefore, the original function of the bellows part can be sufficiently exhibited.

  Of the plurality of bellows portions in the bellows portion 120, when the rotational force is applied to the bellows portion 120, the amount of distortion increases, and the convex portions 121a and 121b are provided on the innermost belly portion 121 where stress is likely to concentrate. ing. Accordingly, stress concentration on the bellows portion 120 can be effectively suppressed.

  As described above, according to the sealing device 100 according to the present embodiment, the stress concentration on the bellows portion 120 can be alleviated. Therefore, even if the rotation and eccentricity of the shaft are repeated, the bellows portion 120 is cracked or split. Can be suppressed. Thereby, durability of the bellows part 120 can be improved. In addition, the eccentric followability, which is the original function of the bellows portion 120, can be sufficiently exhibited.

(Example 2)
FIG. 2 shows a second embodiment of the present invention. In the present embodiment, an example in which the arrangement position of the convex portions is different from that in the first embodiment is shown. Since other configurations and operations are the same as those in the first embodiment, the description of the same components will be omitted as appropriate.

  Similarly to the sealing device 100 according to the first embodiment, the sealing device 200 according to the present embodiment also includes a fixing portion 210, a bellows portion 220, and a seal portion 230. The seal part 230 includes a bumper part 231 and a lip part 232. Since these basic functions are the same as those in the first embodiment, the description thereof will be omitted.

  Also in the sealing device 200 according to the present embodiment, the annular convex portions 221 a and 221 b that increase the rigidity of the bellows portion 220 are provided only on the innermost abdominal portion 221 in the bellows portion 220. These convex portions 221a and 221b are respectively provided on the front and back (inner peripheral side and outer peripheral side) of the abdominal portion 221 near the center in the axial direction. Moreover, these convex parts 221a and 221b are provided concentrically with the shaft. Furthermore, these convex portions 221 a and 221 b are provided integrally with the abdominal portion 221 of the bellows portion 220. That is, these convex portions 221a and 221b are integrally formed on the surface of the belly portion 221 of the bellows portion 220 by molding.

  Thus, in the sealing device 200 according to the present embodiment, the positions of the convex portions 221a and 221b provided on the innermost abdomen 221 in the bellows portion 220 are different from those in the first embodiment. However, the operational effects obtained by providing the convex portions 221a and 221b are the same as in the case of the first embodiment, and the same effect as in the case of the first embodiment can be obtained also in the sealing device 200 according to the present embodiment. it can.

Example 3
FIG. 3 shows a third embodiment of the present invention. In the present embodiment, an example in which the arrangement position of the convex portions is different from that in the first embodiment is shown. Since other configurations and operations are the same as those in the first embodiment, the description of the same components will be omitted as appropriate.

  Similarly to the sealing device 100 according to the first embodiment, the sealing device 300 according to the present embodiment also includes the fixing portion 310, the bellows portion 320, and the seal portion 330. Further, the seal portion 330 includes a bumper portion 331 and a lip portion 332. Since these basic functions are the same as those in the first embodiment, the description thereof will be omitted.

  Also in the sealing device 300 according to the present embodiment, the convex portion 321 a that increases the rigidity of the bellows portion 320 is provided only on the innermost abdominal portion 321 in the bellows portion 320. In the present embodiment, a plurality of convex portions 321 a are provided on the inner peripheral surface of the abdominal portion 321. The plurality of convex portions 321a are provided so as to be inclined with respect to the concentric circle of the shaft so as to extend in the circumferential direction and the axial direction. In addition, these some convex part 321a is provided so that the part enclosed by the several convex part 321a may become a rhombus shape. Further, the plurality of convex portions 321 a are provided integrally with the abdominal portion 321 of the bellows portion 320. That is, the plurality of convex portions 321a are integrally formed on the surface of the belly portion 321 of the bellows portion 320 by molding.

  Thus, in the sealing device 300 according to the present embodiment, the position of the convex portion 321a provided on the innermost abdomen 321 in the bellows portion 320 is different from that in the first embodiment. However, the function and effect obtained by providing the convex portion 321a is the same as in the case of the first embodiment, and the same effect as that in the first embodiment can be obtained also in the sealing device 300 according to the present embodiment. In the case of the present embodiment, since the convex portion 321a is inclined with respect to the concentric circle of the shaft, the convex portion 321a extends not only in the circumferential direction but also in the axial direction. Therefore, the convex portion 321a becomes a resistance force not only against the rotational force acting on the bellows portion 320 but also against the force acting so as to be turned in the axial direction. Therefore, it is possible to prevent the bellows portion 320 from being turned over when the shaft is inserted.

(Other)
Whether the convex portion is provided on the inner peripheral side, the outer peripheral side, or both sides of the belly portion of the bellows portion is not limited to that shown in the above embodiment, and can be appropriately set. Also, the number of convex portions is not limited to that shown in the above embodiment, and can be set as appropriate. In addition, in the case of adopting a configuration in which the convex portion is inclined to the concentric circle of the shaft, in Example 3 described above, the configuration in which the convex portion is not annular is shown, but the convex portion is inclined with respect to the concentric circle of the shaft. Further, it may be configured in an annular shape. In the above embodiment, the case of the steering dust seal is shown as an example of the sealing device, but the present invention can be applied to the sealing device in various devices in which the shaft rotates and is eccentric.

100, 200, 300 Sealing device 110, 210, 310 Fixing part 120, 220, 320 Bellow part 121, 221, 321 Abdominal part 121a, 121b, 221a, 221b, 321a Protruding part 130, 230, 330 Seal part 131, 231, 331 Bumper part 132,232,332 Lip part

Claims (2)

A sealing device for sealing an annular gap between a housing having a shaft hole and a shaft inserted through the shaft hole and configured to rotate and decenter with respect to the housing,
A fixing portion fixed to the inner peripheral side of the shaft hole of the housing;
A thin bellows portion extending in a bellows shape from the fixed portion toward the shaft surface;
A seal portion which is provided on the inner peripheral end side of the bellows portion and slidably contacts the outer peripheral surface of the shaft;
A sealing device comprising:
A sealing device characterized in that a convex portion extending in the circumferential direction, which increases the rigidity of the bellows portion, is provided only on the innermost abdominal surface of the bellows portion.   The sealing device according to claim 1, wherein the convex portion is provided so as to be inclined with respect to a concentric circle of the shaft so as to extend in a circumferential direction and an axial direction.

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