JP6116877B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device according to a sealing technique. The sealing device of the present invention is used, for example, in the field related to automobiles or the field related to railway vehicles (for example, railway vehicle bearing seals), or in the field of general-purpose machines.

  Conventionally, as shown in FIG. 5, a sealing device having a seal lip 51 made of a rubber-like elastic body is known, and the seal lip 51 has a sliding portion 52 with respect to a shaft on its inner peripheral surface, and on its outer peripheral surface. It has a structure for mounting a lip tightening spring 53 (see Patent Document 1).

  However, in this sealing device, since the tightening force by the spring 53 directly acts on the sliding portion 52, the sliding torque generally tends to be large.

  On the other hand, in recent years, for example, in the field of automobiles, there is an increasing demand for reducing the sliding torque of the sealing device for the purpose of improving the fuel consumption, and it is necessary to consider reducing the torque of the conventional shape.

  As a prior art to the present invention, as shown in FIG. 6, there is a sealing device having a structure in which an inner peripheral lip 54 is integrally formed on the inner peripheral side of a seal lip 51 and this inner peripheral lip 54 is brought into contact with a shaft 55. (See Patent Document 2).

  However, in this sealing device, since the sliding portion 52 with respect to the shaft 55 is disposed at the tip of the inner peripheral lip 54, the tightening force by the spring 53 hardly acts on the sliding portion 52, so that the shaft 55 is not reached. There is a problem that the followability to the eccentricity is insufficient.

Japanese Utility Model Publication No. 56-23756 Japanese Utility Model Publication No. 49-2948

  In view of the above, an object of the present invention is to provide a sealing device that can achieve low torque in a sliding portion of a seal lip and can ensure followability with respect to eccentricity of a shaft.

In order to achieve the above object, a sealing device according to claim 1 of the present invention includes a seal lip provided from a lip holding portion toward a target to be sealed, a spring mounted on an outer peripheral surface of the seal lip, and the seal. A bent portion provided radially inward from the tip of the lip, an inner peripheral lip provided from the inner peripheral end of the bent portion toward the outside air, and an inner peripheral surface of the inner peripheral lip. A sliding portion with respect to the shaft, and the sliding portion is disposed on the outside air side with respect to the bent portion and disposed on the sealing target side with respect to the center of the spring, and the inner peripheral lip is disposed on the outside air side. When the inner peripheral lip is lifted outward in the radial direction when the sliding portion comes into contact with the outer peripheral surface of the shaft and the inner peripheral lip is lifted radially outward, the inner periphery of the inner peripheral lip is formed. Parts of the surface other than the sliding part are Away from the peripheral surface, and sets a radial clearance between the outer peripheral surface of the shaft.

  The sealing device according to claim 2 of the present invention is the sealing device according to claim 1, wherein a pumping action during shaft rotation is applied to a portion of the inner peripheral surface of the inner peripheral lip that is closer to the outside air than the sliding portion. The screw part which makes is provided.

  A sealing device according to claim 3 of the present invention is the sealing device according to claim 1, wherein a low friction material made of a fluororesin is covered on the inner peripheral surface of the inner peripheral lip including the sliding portion. It is characterized by being worn.

  In the sealing device of the present invention having the above-described configuration, since the sliding portion with respect to the shaft provided on the inner peripheral surface of the inner peripheral lip is disposed on the outside air side from the bending portion, the tightening force by the spring is It acts on the sliding part after turning around. Therefore, it is possible to reduce the sliding torque generated in the sliding portion as compared with the case where the tightening force by the spring acts directly on the sliding portion (FIG. 5).

  In addition, since the sliding part with respect to the shaft provided on the inner peripheral surface of the inner peripheral lip is arranged on the sealing target side from the center of the spring, the tightening force by the spring goes around the bent part. It acts on the sliding part with an appropriate size. Therefore, the followability of the seal lip with respect to the eccentricity of the shaft can be improved as compared with the case where the sliding portion is arranged at the tip of the inner peripheral lip (FIG. 6).

  Moreover, it is possible to improve the sealing performance of the sealing device by providing a screw portion that performs a pumping action during shaft rotation at a site on the outside air side of the sliding portion on the inner peripheral surface of the inner peripheral lip.

  In addition, by applying a low friction material made of a fluorine resin on the inner peripheral surface of the inner peripheral lip including the sliding portion, it is possible to further reduce the sliding torque generated in the sliding portion. .

  The sliding portion provided on the inner peripheral surface of the inner peripheral lip is generally pointed with a triangular cross section, but the cross sectional shape is not limited, and may be, for example, a rounded shape with a circular arc.

  The present invention has the following effects.

  That is, in the present invention, as described above, since the sliding portion provided on the inner peripheral surface of the inner peripheral lip is arranged on the outside air side from the bent portion, the tightening force by the spring rotates toward the bent portion. Acting on the sliding part. Therefore, the sliding torque can be reduced as compared with the case where the tightening force by the spring acts directly on the sliding portion. Further, since the sliding portion is arranged on the sealing target side from the center of the spring, the tightening force by the spring wraps around the bending portion and acts on the sliding portion with an appropriate size. Therefore, the followability with respect to the eccentricity of the shaft can be improved as compared with the case where the sliding portion is disposed at the tip of the inner peripheral lip. Therefore, as described above, it is possible to provide a sealing device that can reduce the torque in the sliding portion of the seal lip and ensure the followability to the eccentricity of the shaft, as intended.

  In addition, the sealing performance can be improved by providing a threaded portion on the outside air side of the sliding portion on the inner peripheral surface of the inner peripheral lip, and the fluororesin is provided on the inner peripheral surface of the inner peripheral lip including the sliding portion. The sliding torque can be further reduced by applying the low friction material.

Sectional drawing of the principal part of the sealing device which concerns on the Example of this invention. Detailed explanatory drawing of the screw part provided in the sealing device Explanatory drawing which shows the action direction of the clamping force by the spring in the sealing device Sectional drawing of the principal part of the sealing device which concerns on the other Example of this invention. Sectional drawing of the principal part of the sealing device which concerns on a prior art example Half sectional view of a sealing device according to another conventional example

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross section of a main part of a sealing device (oil seal) 1 according to an embodiment of the present invention. The sealing device 1 according to this embodiment is slidable on the peripheral surface of a shaft (rotating shaft) 2 (see FIG. 3) that is mounted on the inner periphery of a shaft hole of a housing (not shown) and is inserted into the shaft hole. It is in close contact, and suppresses leakage of a sealing target existing inside the machine to the outside of the machine and prevents foreign matters such as dust and muddy water existing outside the machine from entering the machine. The inner side is the sealing target side A, and the outer side is the outside air side B.

  The sealing device 1 has a cylindrical fixing portion 11 that is fixed (fitted) to the inner peripheral surface of the shaft hole of the housing. A lip holding portion 12 is integrally provided, and a sealing lip 13 is integrally provided from the inner peripheral end of the lip holding portion 12 toward the sealing target side. In addition, the sealing device 1 includes a rubber-like elastic body 15 covered with a ring member (metal ring) 14 made of a rigid material such as a metal integrally formed with an inward flange portion 14b at an end portion on the outside air side of the cylindrical portion 14a. The seal lip 13 is integrally formed by the latter rubber-like elastic body 15 together with the outer peripheral seal portion 16, the flange covering portion 17 and the dust lip 18.

  An annular mounting groove 19 is provided on the outer peripheral surface of the seal lip 13, and an annular spring (garter spring) 20 is mounted in the mounting groove 19. Since the mounting groove 19 is provided at a position slightly retracted from the front end 13a of the seal lip 13 to the outside air side, the spring 19 is also mounted at a position slightly retracted from the front end 13a of the seal lip 13 to the outside air side.

  An annular bent portion (reversing portion) 21 is integrally provided from the tip 13a of the seal lip 13 inward in the radial direction, and the inner peripheral lip 22 is integrated from the inner peripheral end of the bent portion 21 toward the outside air. Is provided. Therefore, the inner peripheral lip 22 is disposed on the inner peripheral side of the seal lip 13 via the space 23. The axial length of the inner peripheral lip 22 is substantially the same as the axial length of the seal lip 13, so that the inner peripheral lip 22 as a whole has a cylindrical shape or a tapered shape that gradually decreases in diameter toward the front end 22a on the outside air side. Molded.

  A sliding portion 24 with respect to the shaft 2 is provided on the inner peripheral surface of the inner peripheral lip 22. The sliding portion 24 is formed in an annular shape as a tip of a triangular cross section. Therefore, when the sliding portion 24 comes into contact with the outer peripheral surface of the shaft 2 and the inner peripheral lip 22 is lifted radially outward, the inner peripheral surface Parts other than the sliding portion 24 (including the tip 22a) are separated from the outer peripheral surface of the shaft 2, and a radial gap is set between the outer peripheral surface of the shaft 2. As described above, the cross-sectional shape of the sliding portion 24 is not particularly limited, and may be, for example, a rounded shape with a circular arc.

  The sliding portion 24 is arranged on the outside air side of the bending portion 21 with respect to the axial position (arrangement), and the center of the spring 20 mounted in the mounting groove 19 (cross-sectional shape or axial width of the spring 20). 1, the axial position of this center is indicated by the line 20 a in FIG. 1, and the sliding portion 24 is disposed between the bent portion 21 and the center of the spring 20. ing. Therefore, since the sliding portion 24 is disposed at a position relatively close to the bent portion 21 on the inner peripheral surface of the inner peripheral lip 22, the sliding portion 24 contacts the outer peripheral surface of the shaft 2 as described above. When the lip 22 is lifted radially outward, a considerably wide area of the inner peripheral surface of the inner peripheral lip 22 is separated from the outer peripheral surface of the shaft 2.

  In addition, a screw portion 25 is provided on the inner peripheral surface of the inner peripheral lip 22 on the outside air side of the sliding portion 24 to exert a pumping action when the shaft 2 rotates to push the sealed object back to the sealed object side. Is provided. As shown in detail in FIG. 2, the screw portion 25 is composed of a rib (projection) 26 having a triangular cross section, and a large number of the ribs 26 are arranged at equal intervals on the circumference. One end of the screw portion 25 (one end of the rib 26) reaches the outside air inclined surface 24 a of the sliding portion 24 and reaches the pointed end 24 b of the sliding portion 24. The other end of the screw portion 25 (the other end of the rib 26) does not reach the tip 22 a of the inner peripheral lip 22, but may reach the tip 22 a of the inner peripheral lip 22. The height of the screw portion 25 (the height of the rib 26) is set to be equal to or substantially equal to the height of the sliding portion 24.

  The sealing device 1 having the above-described configuration is mounted on the inner periphery of the shaft hole of the housing as described above and is slidably in close contact with the peripheral surface of the shaft 2, and exhibits the following effects by the above-described configuration. It has the characteristics.

  That is, in the sealing device 1 having the above-described configuration, the sliding portion 24 provided on the inner peripheral surface of the inner peripheral lip 22 is disposed on the outside air side with respect to the bending portion 21, and therefore, as shown by an arrow in FIG. The tightening force by the spring 20 moves toward the bending portion 21 and then acts on the sliding portion 24, and the tightening force is dispersed at the bending portion 21. Therefore, the sliding torque generated in the sliding portion 24 can be reduced as compared with the case where the tightening force by the spring acts directly on the sliding portion (FIG. 5).

  In addition, since the sliding portion 24 provided on the inner peripheral surface of the inner peripheral lip 22 is disposed closer to the sealing object than the center of the spring 20, the sliding portion 24 is disposed relatively close to the bending portion 21. ing. Therefore, when the tightening force by the spring 20 wraps around the bending portion 21 and acts on the sliding portion 24 with an appropriate size, the sliding portion is arranged at the tip of the inner peripheral lip (FIG. 6). Compared with, the followability of the seal lip 13 with respect to the eccentricity of the shaft 2 can be improved.

  In the sealing device 1 configured as described above, the sliding portion 24 provided on the inner peripheral surface of the inner peripheral lip 22 is slidably in close contact with the outer peripheral surface of the shaft 2 to seal the object to be sealed. In addition, since the screw portion 25 is provided at a site on the outside air side of the sliding portion 24 on the inner peripheral surface of the inner peripheral lip 22, the sealing target is also sealed by the pumping action exhibited by the screw portion 25. . Therefore, the sealing performance with respect to the object to be sealed can be improved.

  Since the height of the screw portion 25 is set to be equal to the height of the sliding portion 24 as described above, the shaft 2 is inserted into the inner peripheral side of the inner peripheral lip 22 and the shaft 2 When the sliding portion 24 comes into contact with the outer peripheral surface, the screw portion 25 also comes into contact with the outer peripheral surface of the shaft 2 at the same time. Further, when the inner peripheral surface of the inner peripheral lip 22 is parallel to the outer peripheral surface of the shaft 2 in a state where the shaft 2 is inserted on the inner peripheral side of the inner peripheral lip 22, the screw portion 25 extends over the entire length thereof. In contact with the outer peripheral surface of the shaft 2. Therefore, in this case, since the pump effective length is set to be long, the pumping action exhibited by the screw portion 25 is extremely strong.

  The screw portion 25 may be omitted, and a low friction material made of a fluorine-based resin such as PTFE may be attached to the inner peripheral surface of the inner peripheral lip 22 including the sliding portion 24. In this case, the sliding torque generated in the sliding portion 24 can be further reduced. Further, a low friction material made of a fluorine-based resin such as PTFE has an effect of suppressing sliding heat generated in the sliding portion 24.

  In another embodiment shown in FIG. 4, a low-friction material 27 made of a fluororesin such as PTFE is applied with a predetermined thickness over the entire inner peripheral surface of the inner peripheral lip 22 including the sliding portion 24. (Baked). However, the low friction material 27 may be attached to at least a part of the inner peripheral surface of the inner peripheral lip 22 including the sliding portion 24.

DESCRIPTION OF SYMBOLS 1 Sealing device 2 Shaft 11 Fixing part 12 Lip holding part 13 Seal lip 13a, 22a Tip 14 Ring member 14a Cylindrical part 14b Flange part 15 Rubber-like elastic body 16 Outer peripheral seal part 17 Flange covering part 18 Dustrip 19 Mounting groove 20 Spring 20a A line indicating the center of the spring 21 Bent part 22 Inner peripheral lip 23 Space part 24 Sliding part 24a Outside air side slope 24b Point 25 Screw part 26 Rib 27 Low friction material A Sealing target side B Outside air side

Claims (3)

A seal lip provided from the lip holding part toward the sealing target side, a spring attached to the outer peripheral surface of the seal lip, and a bent part provided radially inward from the tip of the seal lip; An inner peripheral lip provided from the inner peripheral end of the bent portion toward the outside air side, and a sliding portion with respect to a shaft provided on the inner peripheral surface of the inner peripheral lip,
The sliding portion is disposed on the outside air side from the bent portion and disposed on the sealing target side from the center of the spring ,
The inner peripheral lip is formed in a taper shape that gradually decreases in diameter toward the tip on the outside air side, and the sliding portion comes into contact with the outer peripheral surface of the shaft so that the inner peripheral lip is lifted radially outward. A portion other than the sliding portion of the inner peripheral surface of the inner peripheral lip is separated from the outer peripheral surface of the shaft, and a radial gap is set between the outer peripheral surface of the shaft and apparatus. The sealing device according to claim 1.
2. A sealing device according to claim 1, further comprising: a screw portion that performs a pumping action at the time of shaft rotation in a portion of the inner peripheral surface of the inner peripheral lip that is closer to the outside air than the sliding portion. The sealing device according to claim 1.
A sealing device, wherein a low friction material made of a fluororesin is adhered to an inner peripheral surface of the inner peripheral lip including the sliding portion.

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