JP2005090756A - Oil seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil seal capable of improving the pumping performance without incurring the oil leakage in a stationary state. <P>SOLUTION: This oil seal has a slant height rib 21 extended from a tip edge 3A of a taper part 3 by a specific distance along an air-side inclined plane 6. The slant height rib 21 is extended from the tip edge 3A of the taper part 3 along the inclined plane 6. A projecting dimension of the slant height rib 21 from the inclined plane 6 is gradually increased in accordance with the separation from the tip edge 3A. As the projecting dimension of the slant height rib 21 is minimum at the tip edge 3A of the taper part 3, the oil leakage can be prevented in a stationary state of a shaft 5. When a part near the tip edge 3A in the slant height rib 21 is worn out, a part adjacent to the worn part in the slant height rib 21 is slidably kept into contact with the shaft 5 to exercise the pumping performance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oil seal having a pump action.

  Conventionally, this type of oil seal has a seal lip 51 including a tapered portion 50 as shown in FIG. The tapered portion 50 is configured such that the tip edge 50 </ b> A is brought into contact with the outer peripheral surface 52 </ b> A of the shaft 52. A plurality of ribs 55 extending from the leading edge 50A and inclined with respect to the leading edge 50A are formed on the air-side inclined surface 53 of the tapered portion 50. The rib 55 has a constant protruding dimension from the air-side inclined surface 53.

  The larger the projecting dimension of the rib 55, the greater the pumping action that pushes oil that has leaked out to the air side back to the oil side.

  By the way, as shown in FIG. 5A, when the tapered portion 50 of the helix rib seal is attached to the shaft 52, the corner 55A of the rib 55 hits the shaft 52. Accordingly, as can be seen from FIG. 5B showing the oil side inclined surface 57 of the taper 50 viewed in the axial direction, the outer peripheral surface 52A of the shaft 52 and the taper are caused by the presence of the rib 55. A gap is generated between the 50 front edges 50A. When this gap is large, oil leaks from the oil side to the atmosphere side through the gap when the shaft 52 is stationary, so that the protruding dimension of the rib 55 is limited to a predetermined value or less.

That is, conventionally, the height of the rib is limited to prevent oil leakage at rest, so that there is a problem that the pump capacity is suddenly insufficient when the rib is worn.
Japanese Patent Laid-Open No. 7-208611

  SUMMARY OF THE INVENTION An object of the present invention is to provide an oil seal that can improve pumping performance without causing oil leakage at rest.

  In order to achieve the above object, the invention of claim 1 includes an annular seal lip in which the tip of a taper that tapers radially inward is brought into contact with the outer peripheral surface of the shaft. The seal lip is an oil seal having a plurality of ribs extending along the air-side inclined surface of the tapered portion and inclined in the circumferential direction with respect to the axial direction. The rib extends along the air-side inclined surface from the tip edge of the tapered portion, and the projecting dimension from the air-side inclined surface is increased as the portion away from the tip edge increases. It is characterized by being a rib.

  According to the first aspect of the present invention, since the slanted rib has the smallest protruding dimension at the tip edge of the tapered portion, it is possible to prevent oil from leaking when the shaft is stationary. Further, when a portion of the inclined high rib close to the tip edge is worn, a portion adjacent to the worn portion of the inclined high rib is slidably contacted with the shaft to exhibit the pumping capacity. Therefore, it is possible to prevent the pump capacity from being lowered even if the rib is worn. Moreover, since the part adjacent to the said wear part slide-contacts with a shaft | axis, the said slanting height rib can always suppress the clearance gap between a front-end | tip part and a shaft, and can prevent the oil leak at the time of a stillness.

According to a second aspect of the present invention, there is provided an annular seal lip configured such that a tip of a taper that tapers inward in the radial direction is brought into contact with the outer peripheral surface of the shaft. An oil seal having a plurality of ribs extending along the air inclined surface of the tapered portion and inclined in the circumferential direction with respect to the axial direction,
The rib extends from the tip edge of the tapered portion by a predetermined dimension in the axial direction, and has a projecting dimension from the air-side inclined surface that is substantially constant, and a predetermined dimension from the parallel part to the axial direction. It is characterized in that it includes a slanted height portion having a protruding dimension larger than that of the parallel portion.

  According to the second aspect of the present invention, the parallel portion having a predetermined dimension is provided on the tip side of the inclined high portion. Therefore, in the case where the oil-side inclined surface of the tapered detail and the front end surface of the parallel part existing on the same plane as the inclined surface are simultaneously created in the cutting process, the cutting position is along the air-side inclined surface of the tapered detail. Even if they deviate, the protruding dimension of the rib from the leading edge can be kept at the protruding dimension of the parallel part smaller than the protruding dimension of the obliquely high part. Therefore, oil leakage when the shaft is stationary can be prevented. Further, when the parallel part is worn, the above-described inclined high part can supplement the pump capacity and improve the pump capacity as in the first aspect of the invention.

  In addition, one reference example includes an annular seal lip that is configured such that the tip of a tapered portion that is tapered radially inward is brought into contact with the outer peripheral surface of the shaft. An oil seal having a plurality of ribs extending along the air-side inclined surface of the detail and inclined in the circumferential direction with respect to the axial direction, wherein the plurality of ribs A first rib extending from the leading edge along the air-side inclined surface by a predetermined dimension, and along the air-side inclined surface from a position axially separated from the leading edge of the tapered portion by a predetermined dimension. It includes a second rib that extends by a predetermined dimension and has a larger protruding dimension from the air-side inclined surface than the first rib.

  According to this reference example, the second rib has a projecting dimension larger than that of the first rib, and is disposed at a position away from the tip edge of the tapered portion by a predetermined dimension. Therefore, when the first rib wears down and the pumping capacity of the first rib decreases, the second rib having a projecting dimension larger than that of the first rib slides on the shaft and exhibits the pumping capacity. Therefore, according to the present invention, since the second rib compensates for the pump capacity decrease due to wear of the first rib, it is possible to prevent the pump capacity from being insufficient. In addition, since the first rib having a smaller projecting dimension than the second rib is extended from the tip edge, the first rib has a gap between the tip edge and the shaft so that oil leaks when the shaft is stationary. Does not cause. Therefore, according to the above one reference example, the pump capacity can be improved without causing oil leakage at rest.

  From another viewpoint, since the second ribs are alternately arranged with respect to the first ribs, the first ribs can be easily lowered and the second ribs can be easily raised, and the stationary oil can be obtained. It is possible to achieve both prevention of leakage and improvement of pump capacity. If the height of the first rib is the same as the height of the second rib, it is impossible to achieve both prevention of oil leakage at rest and improvement of pump capacity.

  According to the first aspect of the present invention, since the slanted rib has the smallest protruding dimension at the tip edge of the tapered portion, it is possible to prevent oil from leaking when the shaft is stationary. Further, when a portion near the tip edge of the inclined high rib is worn, a portion adjacent to the worn portion of the inclined high rib is brought into sliding contact with the shaft to exhibit the pumping ability. Therefore, it is possible to prevent the pump capacity from being lowered even if the rib is worn. Moreover, since the part adjacent to the said wear part slide-contacts with a shaft | axis, the said slanting height rib can always suppress the clearance gap between a front-end | tip part and a shaft, and can prevent the oil leak at the time of a stillness.

  According to the invention of claim 2, since the parallel portion having a predetermined dimension is provided on the tip side of the inclined high portion, the tip side surface of the parallel portion existing on the same plane as the oil side inclined surface of the tapered portion and the inclined surface When the cutting position is simultaneously created in the cutting process, even if the cutting position is shifted along the inclined surface on the air side of the tip, the protruding part of the parallel part is smaller than the protruding part of the oblique high part. Can be kept in size. Therefore, oil leakage when the shaft is stationary can be prevented. In addition, when the parallel part is worn, the above-described inclined height part supplements the pump capacity, and the pump capacity can be improved.

  Further, according to one reference example, the second rib has a larger projecting dimension than the first rib, and is disposed at a position away from the tip edge of the tapered portion by a predetermined dimension. When the pumping capacity of the first rib is reduced, the second rib having a projecting dimension larger than that of the first rib is brought into sliding contact with the shaft to exhibit the pumping capacity. Accordingly, it is possible to prevent the pump capacity from being insufficient. In addition, since the first rib having a smaller projecting dimension than the second rib is extended from the tip edge, the first rib creates a gap between the tip edge and the shaft so that oil leaks when the shaft is stationary. Without oil leakage, oil leakage at rest can be prevented.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

[Reference example]
FIG. 1 shows a cross-section of the main part of a reference example of the oil seal of the present invention. This reference example includes an annular seal lip 1. The seal lip 1 has a base 2 and a tapered portion 3 connected to the base 2. The taper 3 is tapered inward in the radial direction. The leading edge 3 </ b> A of the tapered portion 3 is configured to be brought into sliding contact with the outer peripheral surface 5 </ b> A of the shaft 5. The tapered portion 3 has an air side inclined surface 6 and an oil side inclined surface 7. The air-side inclined surface 6 is formed with a plurality of first ribs 8 extending from the tip edge 3A of the tapered portion 3 along the air-side inclined surface 6 by a predetermined dimension. The first ribs 8 are arranged at predetermined equal intervals in the circumferential direction. The first rib 8 is inclined such that the angle between the first rib 8 and the tip edge 3A is an acute angle θ1. Further, the first rib 8 protrudes from the air-side inclined surface 6 by a predetermined dimension, and forms a mountain range.

  A second rib 10 is formed on the air-side inclined surface 6 between the first rib 8 and the first rib 8. The second ribs 10 have a mountain range that protrudes larger than the first ribs 8 and are arranged at predetermined equal intervals in the circumferential direction, like the first ribs 8. The second rib 10 extends along the air-side inclined surface 6 at the acute angle θ1 from a position separated from the tip edge 3A by a dimension shorter than the axial dimension of the first rib 8. Yes. The extension dimension of the second rib 10 is longer than the extension dimension of the first rib 8.

  In the oil seal having the above configuration, when the shaft 5 and the seal lip 1 rotate relative to each other, oil leaked from the oil side to the atmosphere side through the tip edge 3A is brought to the oil side by the pump action of the first rib 8. Can be pushed back.

  In the oil seal of this reference example, the second rib 10 has a larger projecting dimension than the first rib 8 and is disposed at a position away from the tip edge 3A of the tapered portion 3 by a predetermined dimension. Therefore, when the first rib 8 is worn and the pumping capacity of the first rib 8 is reduced, the second rib 10 having a projecting dimension larger than that of the first rib 8 is brought into sliding contact with the shaft 5 to exhibit the pumping capacity. Therefore, according to this reference example, since the second rib 10 compensates for the pump capacity decrease due to the wear of the first rib 8, it is possible to prevent the pump capacity from being insufficient. In addition, since the first rib 8 having a projecting dimension smaller than that of the second rib 10 is extended from the tip edge 3A, the first rib 8 has oil between the tip edge 3A and the shaft 5 when the shaft 5 is stationary. Do not create leaking gaps. Therefore, according to this embodiment, the pump capacity can be improved without causing oil leakage at rest.

  In this reference example, the second rib 10 is arranged so as to enter a predetermined dimension in the axial direction between the two adjacent first ribs 8, but the second rib 10 extends axially from the first rib 8. The circumferential direction phase of the second rib 10 and the circumferential direction phase of the first rib 8 may coincide with each other.

[First form]
Next, FIG. 2 shows a first embodiment of the present invention. This first embodiment is different from the reference example only in that the first rib 8 and the second rib 10 of the reference example shown in FIG. 1 are replaced with the inclined high rib 21 shown in FIG. Therefore, in the first embodiment, the same parts as those in the reference example are denoted by the same reference numerals, and different points from the reference example will be mainly described.

  The oil seal has a plurality of oblique high ribs 21 formed on the air-side inclined surface 6. The inclined high ribs 21 are arranged at predetermined equal intervals in the circumferential direction along the air-side inclined surface 6. An angle θ2 between the inclined high rib 21 and the tip edge 3A is an acute angle. The inclined rib 21 extends along the inclined surface 6 from the tip edge 3A of the tapered portion 3. The ridge line 21A of the inclined high rib 21 is inclined with respect to the bottom surface 21B, and the projecting dimension of the inclined high rib 21 from the inclined surface 6 is larger as it is away from the tip edge 3A.

  According to the oil seal having the above-described configuration, the slanting height rib 21 has the smallest projecting dimension at the tip edge 3A of the tapered portion 3, and therefore oil can be prevented from leaking when the shaft 5 is stationary. Further, when the portion of the inclined high rib 21 near the tip edge 3A is worn, the portion of the inclined high rib 21 adjacent to the worn portion slides on the shaft 5 and exhibits the pumping capacity. Therefore, even if the rib 21 is worn, it is possible to prevent the pump capacity from being lowered. In addition, since the inclined high rib 21 is in sliding contact with the shaft 5 at the portion adjacent to the worn portion, the gap between the tip 3 and the shaft 5 can always be suppressed to the minimum, and oil leakage at rest can be prevented.

[Second form]
Next, the principal part of the 2nd form of the oil seal of this invention is shown in FIG. The second embodiment is different from the reference example only in that the rib 31 shown in FIG. 3 is provided in place of the oblique height rib 21 of the first embodiment shown in FIG. Therefore, in the second embodiment, points different from the first embodiment will be mainly described.

  The oil seal according to the second embodiment includes a plurality of ribs 31 formed on the air-side inclined surface 6. The ribs 31 are arranged at predetermined equal intervals in the circumferential direction along the air-side inclined surface 6.

  The rib 31 has a parallel portion 32 and an inclined height portion 33. The parallel portion 32 extends from the distal end edge 3A of the tapered portion 3 by a predetermined dimension in the axial direction, and the protruding dimension from the air-side inclined surface 6 is constant. The obliquely high portion 33 extends from the end of the parallel portion 32 by a predetermined dimension in the axial direction, and the projecting dimension is larger than the parallel portion 32 in a portion farther from the parallel portion 32. The ridge line 33A is inclined.

  In the second form of the above configuration, since the parallel portion 32 having a predetermined size is provided on the tip side of the inclined height portion 33, the oil side inclined surface 7 of the tapered portion 3 and the inclined surface 7 are present on the same plane. In the case where the tip surface 32A of the parallel part 32 is manufactured simultaneously in the cutting process, even if the cutting position is shifted along the atmosphere-side inclined surface 6 of the tapered portion 3, the protruding dimension of the rib 31 at the tip edge 3A is inclined. The protruding dimension of the parallel part 32 can be kept smaller than the protruding dimension of the high part 33. Therefore, oil leakage when the shaft 5 is stationary can be prevented. Further, in the second embodiment, since the inclined portion 33 supplements the pumping capacity when the parallel part 32 is worn, the pumping capacity when the rib is worn can be improved as in the first embodiment.

It is sectional drawing which shows the principal part of the reference example of the oil seal of this invention. It is principal part sectional drawing of the 1st form of this invention. FIG. 3 is a diagram showing the main part of the second embodiment of the present invention. It is sectional drawing which shows the principal part of the conventional oil seal. FIG. 5A is a view partially showing a state where the conventional example is mounted on the shaft, and FIG. 5B is a view showing a state where the state is viewed in the axial direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Seal lip, 2 ... Base part, 3 ... Tapering, 3A ... Tip edge, 5 ... Shaft,
5A ... outer peripheral surface, 6 ... air side inclined surface, 7 ... oil side inclined surface, 8 ... first rib,
10 ... 2nd rib, 21 ... Oblique height rib, 31 ... Rib, 32 ... Parallel part,
33 ... Slope height.

Claims (2)

It has an annular seal lip that is adapted to contact the outer peripheral surface of the shaft with the tip of the taper tapered radially inward, and this seal lip is formed on the air-side inclined surface of the taper. An oil seal having a plurality of ribs extending along a circumferential direction with respect to an axial direction,
The plurality of ribs extend along the air-side inclined surface from the tip edge of the taper, and the projecting dimension from the air-side inclined surface increases as the portion is farther from the tip edge. An oil seal characterized by being a slanted high rib. It has an annular seal lip that is adapted to contact the outer peripheral surface of the shaft with the tip of the taper tapered radially inward, and this seal lip is formed on the air-side inclined surface of the taper. An oil seal having a plurality of ribs extending along a circumferential direction with respect to an axial direction,
The rib extends from the tip edge of the tapered portion by a predetermined dimension in the axial direction, and has a projecting dimension from the air-side inclined surface that is substantially constant, and a predetermined dimension from the parallel part to the axial direction. The oil seal is characterized in that it includes a sloped portion that extends only by a distance from the parallel portion and has a larger projecting dimension than the parallel portion.

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