JP2006189116A - Oil seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil seal arranged in an annular space of which rotary shaft rotates in both directions and having screw groove provided on an atmospheric air side inclined surface of a lip part, not leaking oil from the screw groove provided to have a pump function at a time of reverse rotation in a high speed rotation zone and securing sealing nature by the screw groove. <P>SOLUTION: In the oil seal to make sliding contact with the rotary shaft at a sliding contact section of the lip part 51, a gap 54 is formed between a tip 61 of the screw groove 6 and a lip edge 53 of the lip part 51, the screw grove 6 does not make sliding contact with the rotary shaft but demonstrates screw effect when a sliding contact section 55 makes sliding contact with the rotary shaft over whole circumference at an early stage of wear. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oil seal that is used for both high-speed rotations and that has a thread on the atmospheric-side slope of a seal lip.

  Conventionally, for example, an oil seal 101 shown in FIG. 5 is known. The oil seal 101 includes an annular member 102 having a substantially L-shaped cross section that is fitted in the shaft hole, and an outer peripheral surface of a rotating shaft (not shown) in which a base portion is bonded to the annular member 102 and a lip portion 103 is inserted into the shaft hole. A seal lip 104 made of a rubber-like elastic body that is in sliding contact with the seal and a garter spring 105 that is provided on the outer peripheral side of the lip portion 103 and applies an axial tension force. This prevents leakage from the outer peripheral surface of the rotating shaft to the atmosphere side B.

  In order to improve the sealing performance of the oil seal 101, the atmosphere-side inclined surface 103 a of the lip portion 103 has a specific inclination angle with respect to the rotation direction during forward rotation and reverse rotation, and the tip of the lip portion 103 A thread 107 reaching the lip edge 106 is provided. Since the screw 107 is provided on the atmosphere-side inclined surface 103a, the lip edge 106, which is a sliding contact portion 108 with the outer peripheral surface of the rotary shaft, and the lip edge 106 are provided by the screw 107A provided in the rotation direction α at the time of shaft rotation. Air is supplied toward the vicinity, and a pump function is performed in which a fluid that flows out to the atmosphere side B is pushed back to the sealing target side A.

  However, in the high-speed rotation region, the oil splash from the screw 107B provided to have a pump function when rotating in the opposite direction with respect to the rotation direction α cannot be sufficiently collected, and leakage in a state of being scattered in the form of oil droplets is recognized. . Since the tip of the thread 107 extends to the lip edge 106, as shown in FIGS. 6 to 8, when the lip 103 is in sliding contact with the outer peripheral surface of the rotating shaft, not only the sliding contact portion 108 of the lip 103 but also the thread. This is because the tip of 107 also comes into sliding contact with the outer peripheral surface of the rotating shaft, and a minute gap 109 is generated at the base of the screw 107. That is, in the high-speed rotation region, the minute gap 109 generated at the base of the screw 107B provided to have a pump function when rotating in the opposite direction with respect to the rotation direction α becomes an oil flow path, and passes through the minute gap 109. There was a problem that a trace amount of oil scattered in the direction of the broken line arrow β could not be recovered sufficiently.

  In addition, in the following patent document, a part of the screw provided on the inclined surface on the atmosphere side of the lip part is placed at a position where the tip does not reach the lip edge, so that proper sealing performance can be obtained even at the stage where wear has progressed. The oil seal provided with a thread having a specific inclination angle with respect to the rotation direction at the time of forward rotation and reverse rotation has a pump function at the time of rotation opposite to the rotation direction. No countermeasures have been disclosed for oil leakage from the provided thread.

Utility Model Registration No. 2598237

  In view of the above, the present invention is an oil seal in which a rotating shaft is disposed in an annular space that rotates in both directions, and a thread is provided on the inclined surface on the atmosphere side of the lip portion. On the other hand, an object of the present invention is to provide an oil seal that does not cause oil leakage from a screw provided so as to have a pump function when rotating in the opposite direction, and that ensures sealing performance by the screw.

  In order to achieve the above object, the oil seal according to claim 1 of the present invention is provided with a screw thread for both rotations on the inclined surface on the atmosphere side of the lip portion of the seal lip, and the sliding contact between the one member and the lip portion. In the oil seal that is in sliding contact with the part, a gap is formed between the tip of the thread and the lip edge of the lip portion, and the sliding contact part is in sliding contact with the one member over the entire circumference at the initial stage of wear. Then, the screw is provided in a non-contact state on the one member.

  The present invention has the following effects.

  That is, in the oil seal of the present invention having the above-described configuration, a gap is provided between the tip of the thread and the lip edge, and the sliding contact portion of the lip portion is slidably contacted with one member at the initial stage of wear. Since the screw provided on the inclined surface on the atmosphere side of the lip portion of the seal lip is in a non-contact state, the screw provided for the purpose of performing a screw function when rotating in the opposite direction with respect to the rotation direction. A minute gap serving as a flow path of oil generated by sliding the base in contact with one member is not formed, and oil leakage can be prevented. In addition, since the screw is provided in a non-contact state with one member but exhibits a screw effect, the screw provided for the purpose of performing a screw function in the rotational direction is Although it does not slidably contact the member, air is supplied toward the slidable contact portion, and the pumping effect of pushing back the oil that is about to flow out to the atmosphere side is exhibited, and the sealing performance can be ensured.

  Preferred embodiments of the present invention will be described below with reference to the drawings. However, the scope of the present invention is not intended to be limited to the contents described in this embodiment unless otherwise specified.

  1 and 2 are half sectional views showing an oil seal according to an embodiment of the present invention, and FIGS. 3 and 4 are explanatory views showing a state in which the oil seal is in contact with a rotating shaft. It is configured as follows.

  As shown in FIG. 1, the oil seal 1 includes an annular member 2, a seal lip 3, and a garter spring 4.

  The annular member 2 includes a cylindrical portion 21 that is fitted in a housing that is another member, and a flange portion 22 that extends in the inner circumferential direction from the end portion on the atmosphere side B of the cylindrical portion 21.

  The seal lip 3 is a rubber-like elastic body, and a fixed sealing portion 31 that is vulcanized and bonded so as to cover the inner peripheral end of the flange portion 22 of the annular member 2, and the fixed sealing portion 31. Sealing object that seals the dust seal lip 32 that extends to the atmosphere side B that seals foreign matter that is molded and vulcanized into the atmosphere mainly from the atmosphere side B, and oil that is a sealing fluid flows out to the atmosphere side B A garter spring 4 is provided on the outer peripheral side of the lip portion 51 of the oil seal lip 5 to give a pressing force so that the oil seal lip 5 can follow the variation in the radial direction. A recess 52 for mounting is formed.

  A screw 6 is provided on the atmosphere-side B inclined surface 51 a of the lip portion 51. The thread 6 has a convex shape with respect to the inclined surface 51a, and oil that is a fluid to be sealed is directed to the sealing target side A with respect to the rotation direction (arrow α in FIG. 1) when the rotating shaft that is one member rotates forward. The forward rotation screw 6A having a specific inclination angle that makes an angle to push back, and the oil that is the sealing target fluid to the sealing target side A with respect to the rotation direction during the reverse rotation (the direction opposite to the arrow α in FIG. 1). A plurality of reverse-rotating threads 6B having a specific inclination angle that forms an angle to be pushed back are provided alternately in groups.

  As shown in FIG. 2, the screw 6 is provided so that both the forward rotation screw 6A and the reverse rotation screw 6B extend from the atmosphere side B toward the lip edge 53, but the tip 61 has a lip edge. It does not extend to 53 but remains at a position retracted to the atmosphere side A, and a gap 54 is provided between the tip 61 of the screw 6 and the lip edge 53. The position of the tip 61 of the lip edge 6 is formed when the lip edge 53 of the lip portion 51 and the air side diameter inclined surface 51a in the vicinity thereof are in sliding contact with the rotating shaft 7 over the entire circumference in the initial stage of wear. Although it does not reach the sliding contact portion 55, it is close to the end 56 on the atmosphere side B of the sliding contact portion 55, and is provided within a range where the function as the screw 6 can be achieved.

  That is, as shown in FIGS. 3 and 4, the distal end 61 of the thread 6 has a peripheral surface 71 of the rotating shaft 7 even when the sliding contact portion 55 of the lip portion 51 is in sliding contact with the rotating shaft 7 over the entire circumference. In a non-contact state, a slight height gap 57 is formed between the rotary shaft 7 and the peripheral surface 71. However, the height gap 57 supplies air toward the sliding contact portion 55 accompanying the rotation of the rotary shaft 7 which is a function of the screw 6, and the oil that is about to flow out to the atmosphere side B is pushed back to the sealing target side. It is set in a range where a screw effect can be produced.

  Therefore, the screw 6 provided on the air-side inclined surface 51a of the lip portion 51 of the oil seal lip 5 has the sliding contact portion 55 of the lip portion 51 at the initial stage of wear sliding on the rotating shaft 7 over the entire circumference. Even if they are in contact with each other, they are not in contact with each other, so that no minute gap is formed between the outer peripheral surface 71 of the rotary shaft 7 and an oil flow path. Moreover, since it is provided in a position where it is in a non-contact state but exhibits a screw effect, it exhibits a pumping effect in which air is supplied toward the sliding contact portion 55 and oil that is about to flow out to the atmosphere side B is pushed back. It becomes possible to ensure the sealing performance.

  The length of the screw, the set angle, and the like are set as appropriate within the range in which the spiral effect is exhibited, and reversely rotated with the forward rotation screw formed so as to exhibit the screw effect during forward rotation. The setting may be different from the thread for use.

  Furthermore, the screw 6 only needs to be in a non-contact state with the rotary shaft 7 in the early stage of wear, and the height gap 57 may be set so as to come into sliding contact with wear of the sliding contact portion 55. This prevents the circumferential line of the lip edge 53 from being disturbed due to the thread 6 in sliding contact with the rotating shaft 7 at the initial stage of wear, prevents oil leakage from easily occurring, and progress of wear of the sliding contact portion 55. Accordingly, it is possible to minimize the disturbance of the circumferential line of the lip edge 53 by bringing the screw 6 into sliding contact with the rotating shaft 7.

Partial sectional view of an oil seal lip according to the present invention Explanatory drawing which expanded the principal part in FIG. Explanatory drawing which shows the state of a thread when the lip | rip part which concerns on this invention is slidably contacted Explanatory drawing which shows the state which the lip | rip part which concerns on this invention contacted Partial sectional view of an oil seal lip according to a conventional example Explanatory drawing which shows the state which the lip | rip part which concerns on a prior art example slidably contacted Explanatory drawing which expanded the principal part in FIG. Explanatory drawing which shows the state of a thread when the lip | rip part which concerns on a prior art example is slidably contacted

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil seal 2 Annular member 21 Cylindrical part 22 Flange part 3 Seal lip 31 Fixed sealing part 32 Dust seal lip 4 Garter spring 5 Oil seal lip 51 Lip part 51a Inclined surface 52 Recessed part 53 Lip edge 54, 57 Gap 55 Sliding part 56 End Part 6 Thread 61 Tip 7 Single member (rotating shaft)
71 Circumference α Rotation direction A Sealing target side B Atmosphere side

Claims (1)

In the oil seal in which a screw thread for both rotations is provided on the atmosphere-side inclined surface of the lip portion of the seal lip, and in sliding contact with one member at the sliding contact portion of the lip portion,
When a gap is formed between the tip of the thread and the lip edge of the lip portion, and when the sliding contact portion is slidably contacted with the one member over the entire circumference, the thread is An oil seal provided in a non-contact state on one member.

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