JP2008095754A - Hermetic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hermetic device capable of suppressing not only squeaking sound which is likely generated during low speed rotation but also a sliding sound generated during high speed rotation. <P>SOLUTION: In the hermetic device 10 provided with a seal lip 18 with a sliding surface 23 for slidable contact with a sealing surface 36A of a counterpart member 36, a plurality of projections 30 are formed with intervals in a sliding direction are formed in the sliding surface 23. The projection is formed so that it extends vertically to the sliding direction and a length in a direction vertical to the sliding direction is longer than a width in the sliding direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sealing device such as an oil seal.

  Patent Document 1 listed below discloses an oil seal provided between a housing of an oil pump and a rotating shaft. This oil seal is obtained by fixing an elastic member to a metal core member, and a seal lip and a dust lip are formed on the inner peripheral portion of the elastic member. The seal lip is formed with an oil-side inclined surface and an atmospheric-side inclined surface that are inclined in opposite directions, and the atmospheric-side inclined surface is a slidable contact surface that mainly contacts the outer peripheral surface of the rotating shaft.

  As the atmosphere-side inclined surface moves away from the boundary with the oil-side inclined surface in the axial direction, the contact surface pressure with the rotating shaft decreases. When insufficient lubrication occurs in such a portion, a squeak noise is likely to occur due to the stick-slip phenomenon. Such a squealing noise is likely to occur in a low-speed rotation range such as when the rotary shaft is activated.

  On the other hand, Patent Document 2 discloses a seal member for a rolling bearing as a technique related to an oil seal, and this seal member forms fine irregularities on a sliding contact surface that is in sliding contact with an inner ring of the rolling bearing. The generation of the above-mentioned squeal is prevented by retaining oil in the concave and convex valley portions.

No. 7-46838 JP 2005-273854 A

  With the technique of Patent Document 2, it has been found that although it is possible to prevent squealing noise that is likely to occur in a low-speed rotation region, it is not possible to prevent sliding sound that is likely to occur in a high-speed rotation region. Furthermore, the high-speed rotation has a problem that the sliding noise is increased as compared with a general seal member in which unevenness is not formed on the sliding contact surface. This is thought to be because minute vibrations repeat minute vibrations by sliding on the seal surface.

  The present invention has been made in view of such circumstances, and a sealing device capable of suppressing not only a squealing sound that is likely to occur during low-speed rotation but also a sliding sound that is likely to occur during high-speed rotation. The purpose is to provide.

The present invention has an annular seal lip having an inner periphery with a sliding contact surface slidably contacting a sealing surface of a mating member, and sealing the fluid by contact between the sealing surface and the sliding contact surface In the device
A plurality of protrusions are formed on the sliding contact surface at intervals in the sliding direction. The protrusions extend perpendicular to the sliding direction and have a length in the direction perpendicular to the sliding direction. It is characterized by being formed larger than the width in the sliding direction.

Here, the fact that the protrusion is perpendicular to the sliding direction means that the center line in the width direction of the protrusion is substantially perpendicular to the sliding direction.
According to this, when the sliding surface of the seal lip slides on the seal surface of the mating member such as the shaft, the ridge is liable to fall in the sliding direction. As a result, the frictional resistance is reduced, and particularly when the sliding speed is low, the generation of squealing noise can be prevented. In addition, since the ridges easily fall in the sliding direction, the starting torque is reduced, and the shaft and the like can be rotated smoothly. When the sliding speed is high, it is difficult to return from the state in which the ridge has fallen to the standing state, so that minute vibrations are reduced and generation of sliding noise can be suppressed.

  An inner peripheral surface of the seal lip is formed in a tapered shape toward the radially inner side, and a fluid-side inclined surface and an atmosphere-side inclined surface that are inclined in directions opposite to each other with the tip edge as a boundary are adjacent to each other. When the atmosphere side inclined surface constitutes the sliding contact surface, the protrusion is formed at a position away from the tip edge of the boundary between the fluid side inclined surface and the atmosphere side inclined surface. Preferably it is. Accordingly, it is possible to prevent fluid from leaking from the boundary edge due to the presence of the protrusion.

  According to the present invention, it is possible to suitably suppress a squeaking sound that is likely to occur when the sliding surface slides at a low speed relative to the seal surface and a sliding sound that is likely to occur when the sliding surface slides at a high speed.

  FIG. 1 is a perspective view of an oil seal (sealing device) 10 according to a first embodiment of the present invention. The oil seal 10 is formed in an annular shape, and an outer peripheral portion thereof is fixed to, for example, a housing 35 of an oil pump, and an inner peripheral portion is slidably contacted with a mating member such as a rotary shaft 36, and the lubricating oil sealed in the housing 35, etc. To seal. The oil seal 10 is formed by vulcanizing and bonding a metal core member 11 and an elastic member 12. The metal core member 11 has an L-shaped cross section by a portion 14 parallel to the axial direction and a vertical portion 15. It is formed by bending. The elastic member 12 is bonded so as to cover the outer peripheral surface of the parallel portion 14 and the one axial side surface of the vertical portion 15 of the metal core member 11, and includes a seal lip 18 and a dust lip 19 on the radially inner side. A tightening spring 13 for assisting a tightening force is provided on the outer peripheral surface of the seal lip 18.

The dust lip 19 extends toward the rotary shaft 36 and prevents dust from passing between the dust strip 19 and the rotary shaft 36. Further, the dust lip 19 extends obliquely in a direction away from the seal lip 18.
The seal lip 18 is disposed on the inner peripheral side of the parallel portion 14 of the core member 11 and has a concave groove 18a for fitting the tightening spring 13 on the outer peripheral surface thereof, and the inner peripheral surface is radially inward. It has a tapered shape toward. Therefore, on the inner peripheral surface of the seal lip 18, two inclined surfaces 20 and 23 are formed on both sides in the axial direction with the tapered tip edge (boundary edge) 24 as a boundary, which are inclined in opposite directions.

  One inclined surface 20 disposed away from the dust lip 19 is an oil side (fluid side) inclined surface disposed on the oil holding side, and the other inclined surface 23 disposed on the dust lip 19 side is the atmospheric air. It is a side (air side) inclined surface. The atmosphere-side inclined surface 23 constitutes a sliding contact surface that mainly contacts the outer peripheral surface (seal surface) 36 </ b> A of the rotating shaft 36. The seal lip 18 is curved radially outward by contacting the outer peripheral surface 36A of the rotary shaft 36, and contacts the outer peripheral surface 36A in a wide range of the sliding contact surface (atmosphere side inclined surface) 23. The seal lip 18 is shown in an uncurved state.

  On the sliding contact surface (atmosphere side inclined surface) 23 of the seal lip 18, a large number of protrusions 30 extending perpendicularly to the circumferential direction (sliding direction; rotational direction) X are formed at equal intervals in the circumferential direction. . The protrusion 30 is formed such that an axial length L (a length in a direction perpendicular to the circumferential direction) L is larger than a circumferential width W. 2 is a cross-sectional view taken along the line II-II in FIG. 1. The protrusion 30 has a circumferential width W of, for example, 200 μm or less, and a protrusion height H from the sliding contact surface 23 of, for example, 5 to 5. 50 μm. The width W in the circumferential direction of the ridge 30 is substantially the same in the entire length of the ridge 30 in the axial direction, and the center line in the width direction is perpendicular to the circumferential direction.

The entire top surface 30 a of the protrusion 30 is in contact with the outer peripheral surface 36 </ b> A of the rotating shaft 36. Further, the protrusion 30 is not formed in the vicinity of the tip edge 24, and the sliding surface 23 is in direct contact with the outer peripheral surface 36A in the vicinity of the tip edge 24.
The contact pressure of the sliding contact surface 23 with respect to the rotation shaft 36 is higher as it is closer to the tip edge 24 and lower as it is farther away. Also, the lubrication state between the outer peripheral surface 36A of the rotary shaft 36 is better as it is closer to the tip edge 24 (oil side), and the lubrication is likely to be insufficient as the distance from the tip edge 24 is increased. Therefore, the squeak noise caused by the stick-slip phenomenon is more likely to occur in the part farther from the tip edge 24.

In this respect, in the present embodiment, the protrusion 30 is provided on the sliding contact surface 23 of the seal lip 18, and the circumferential width W of the protrusion 30 is smaller than the axial length L. As shown in FIG. 3, the protrusion 30 is easily tilted (inclined) in the circumferential direction X by the rotation of the rotating shaft 36. Therefore, in a low-speed rotation range (for example, 100 to 200 min ⁻¹ ) such as at the time of starting rotation, the speed dependency of the friction coefficient becomes small (the negative gradient of the friction coefficient with respect to the rotation speed becomes small), the friction coefficient becomes small, The self-excited vibration of the ridge 30 due to the stick-slip phenomenon is difficult to occur. Thereby, generation | occurrence | production of a squeal can be suppressed. Moreover, since the friction coefficient at the time of rotation starting becomes small, starting torque is reduced and rotation can be started smoothly.

Further, since the protrusion 30 has a length L in the axial direction larger than a width W in the circumferential direction, it is difficult for the protrusion 30 to return from the state of falling in the circumferential direction to the standing state. This is because the protrusion 30 is always in contact with the outer peripheral surface 36A of the rotating shaft 36 at any position within the range of the axial length L of the sliding contact surface 23 with respect to the roughness of the seal surface. Because it is. For this reason, in the high-speed rotation range (for example, 1500 min ⁻¹ ), the ridge 30 does not perform minute vibrations that go back and forth between the collapsed posture and the upright posture, and the generation of sliding noise due to the vibrations is not generated. It is suppressed.

  Further, the protrusion 30 is formed at a position slightly away from the front end edge 24 of the seal lip 18 to the atmosphere side, and is not present in the vicinity of the front end edge 24. Therefore, the vicinity of the front end edge 24 and the rotary shaft 36 are connected to each other. Can be in close contact. Thereby, the oil leakage from between the front-end edge 24 and the rotating shaft 36 can be prevented.

  FIG. 4 is a perspective view of the oil seal 10 according to the second embodiment of the present invention. In the present embodiment, helix ribs 38 extending at an angle θ with respect to the tip edge 24 from the tip edge 24 toward the atmosphere side sloped surface 23 side on the atmosphere side inclined surface 23 of the seal lip 18 are spaced apart in the circumferential direction. A large number are provided. Furthermore, the same number of helix ribs 38 as the ridges 30 are formed, and are connected to the ridges 30. The cross-sectional shape of the helix rib 38 is a mountain shape, and oil leaked out of the oil seal 10 by a so-called pump action can be returned to the oil side.

  Although the technique regarding the helix rib 38 is conventionally well-known (for example, refer the said patent document 1), in this embodiment, the helix rib 38 is provided only in the vicinity of the front end edge 24 in which the protrusion 30 is not provided, Moreover, the ridges 30 are continuously provided. Therefore, the ridge 30 and the helix rib 38 are in a bent shape having a hemispherical shape.

In order to verify the effects of the first and second embodiments of the present invention as described above, tests relating to generation of squealing noise and sliding noise were performed. The contents and results of the test will be described below.
FIG. 5 is a schematic view of the test apparatus, FIG. 6 is a front view of the test piece, and FIG. 7 is a partial perspective view of a portion VII in FIG. In FIG. 5, the test apparatus 40 supports a motor 41 on a base 40 </ b> A, and a movable base 46 is provided so as to be close to and away from the motor 41. A test shaft 42 arranged horizontally is attached to the output shaft of the motor 41. A mounting table 47 is provided on the movable table 46 via a load cell 44, and a test piece 45 is mounted on the mounting table 47 so as to face the tip surface of the test shaft 42.

  In the test, the movable base 46 was moved to the motor 41 side to press the test piece 45 against the test shaft 42 with a predetermined force, and the sound generated by the sliding contact between both 45 and 42 was measured by the needle microphone 43. The test shaft 42 was formed of SUJ2 (bearing steel), and the center line average roughness Ra of the tip surface was 0.04 μm.

  As shown in FIG. 6, the test piece 45 is obtained by projecting an annular projection 52 on the surface of the base 51 attached to the mounting base 47 (FIG. 5). The protrusion 52 has an outer diameter φe1 of 10 mm, an inner diameter φe2 of 6 mm, and a height f of 2 mm. And the test piece 45 equivalent to this invention and the test piece 45 which concerns on a comparative example were created, respectively. Table 1 summarizes the test pieces 45.

In Table 1, A is Comparative Example 1, and the top surface of the protrusion 52 is substantially flat. The center line average roughness Ra of the top surface of the protrusion 52 was 0.2 μm.
B is a comparative example 2 in which fine irregularities 53 are formed on the top surface of the protrusion 52 as shown in FIG. The center line average roughness Ra of the top surface of the protrusion 52 was 3.4 μm. This test piece 45 was molded using a mold having a fine uneven surface formed by sandblasting (grain size # 20).
C is Comparative Example 3, and as shown in FIG. 7B, a cylindrical protrusion 54 is formed on the top surface of the protrusion 52. The test piece 45 was molded using a mold in which a cylindrical depression was formed by etching, and the dimension a in FIG. 7B was set to 100 μm and the dimension b was set to 8 μm.

D is the present invention 1, and as shown in FIG. 7C, a rectangular parallelepiped protrusion 55 (corresponding to the protrusion 30 of the present invention (FIGS. 1 and 4)) is placed around the top surface of the protrusion 52. A plurality are formed in the direction. The test piece 45 was molded using a mold in which a rectangular parallelepiped groove was formed by etching, and the dimension c in FIG. 7C was set to 95 μm and the dimension d was set to 8 μm. The protrusion 55 has a substantially constant width dimension c in the entire length direction of the dimension d, and the center line in the width direction of the protrusion 55 substantially coincides with the radial direction of the protrusion 52 (FIG. 6). ing.
E is the present invention 2, and is the same as the present invention 1 of D except for the dimensions c and d in FIG. The dimension c is 260 μm and the dimension d is 60 μm, and the protrusion 55 is formed larger than the first aspect.
In the first and second aspects of the present invention, the relative angle (center angle of the protrusion 52) θ between the adjacent protrusions 55 is set to 15 °.

As other test conditions, the contact surface between the test piece 45 and the test shaft 42 is in a dry (non-lubricated) state, and the rotation speed of the test shaft 42 is 100 min ⁻¹ (Test 1) and 1500 min ⁻¹ (Test 2). It was. The vertical load applied to the contact surface between the test piece 45 and the test shaft 42 was 1.5N.

In Test 1, the test shaft 42 was rotated at a low speed (100 min ⁻¹ ), and the occurrence of squealing was examined. FIG. 8 is a graph showing the sound pressure level (Sound Level) in Test 1 as an FFT power spectrum. In this graph, only A (Comparative Example 1) and D (Invention 1) are shown. In A (Comparative Example 1), a maximum of 60 dB is shown in the vicinity of 9 kHz, and the sound pressure level is high even in the frequency range before and after that. On the other hand, in D (Invention 1), the sound pressure level is a little less than 30 dB at around 5.3 kHz, but is approximately 20 dB or less in other frequency ranges, and in particular, approximately 10 dB or less in the frequency range of 10 kHz or more. It was. From this result, it can be seen that in the first aspect of the present invention, the generation of squealing in the low-speed rotation range is suitably suppressed. Although not shown in the graph, B (Comparative Example 2) and E (Invention 2) also had a low sound pressure level in a similar manner to Invention 1, and the generation of squealing could be suppressed. In C (Comparative Example 3), the generation of a squeal was confirmed.

In Test 2, the test shaft 42 was rotated at a high speed (1500 min ⁻¹ ), and the occurrence of sliding noise was examined. FIG. 9 is a graph showing the sound pressure level in Test 2 as an FFT power spectrum. In the frequency range up to 9 kHz, A to C (Comparative Examples 1 to 3), D and E (Inventions 1 and 2) change at substantially the same sound pressure level. In the frequency range exceeding 9 kHz, A (Comparative Example 1) showed the lowest sound pressure level. Next, the sound pressure level increased in the order of D (Invention 1), E (Invention 2), B (Comparative Example 2), and C (Comparative Example 3).

  From the above results, in Comparative Example 1 of A, the sliding sound in the high speed rotation range is the smallest, but the squeaking sound in the low speed rotation range becomes large. In Comparative Example 2 of B, although the squealing sound in the low speed rotation region can be suppressed, the sliding sound in the high speed rotation region becomes slightly louder. In Comparative Example 3 of C, the squeaking sound in the low speed rotation region and the high speed rotation region. Both the sliding noise and the sound are large. On the other hand, in the present inventions 1 and 2 of D and E, the sound pressure level was slightly higher in the high-speed rotation range than in Comparative Example 1 of A. 1 is significantly reduced. Therefore, it can be seen that the present inventions 1 and 2 can suppress the squealing sound in the low-speed rotation region and the sliding sound in the high-speed rotation region with a good balance. Further, it can be seen that the condition of the present invention 1 is superior to the present invention 2 in terms of suppression of sliding noise in the high-speed rotation region.

  The present embodiment is not limited to the above-described embodiment, and can be appropriately changed in design. For example, in the first embodiment, the ridge 30 can be formed over the entire axial length of the atmosphere-side inclined surface 23. In this case, in the portion of the ridge 30 that is in contact with the outer peripheral surface 36A of the rotating shaft 36, the length in the direction perpendicular to the sliding direction is made larger than the width in the sliding direction as in the first embodiment. The effect is obtained. Moreover, in 1st, 2nd embodiment, the protrusion 30 may extend | stretch to the part which does not contact 36 A of outer peripheral surfaces of the rotating shaft 36 of the atmosphere side inclined surface 23. FIG. Also in these cases, in the portion of the ridge 30 that is in contact with the outer peripheral surface 36A of the rotating shaft 36, the length in the direction perpendicular to the sliding direction is made larger than the width in the sliding direction in the first embodiment. The same effect can be obtained.

  In the second embodiment, the helix rib 38 can be formed at a position shifted in the circumferential direction from the protrusion 30, and can be formed more or less than the protrusion 30. In the above embodiment, the seal lip is brought into direct contact with the rotary shaft 36, but may be brought into contact with another member (such as a slinger) provided on the rotary shaft 36 side. Further, the sealing device of the present invention may not be provided with the dust strip 19.

It is a section perspective view of the oil seal concerning a 1st embodiment of the present invention. FIG. 2 is a cross-sectional view taken along arrow II-II in FIG. It is sectional drawing equivalent to FIG. 2 which shows a mode that a protrusion fell in the circumferential direction. It is a section perspective view of the oil seal concerning a 2nd embodiment of the present invention. It is the schematic of a test apparatus. It is a front view of a test piece. It is a fragmentary perspective view of the VII part of FIG. It is the graph which represented the sound pressure level with the FFT power spectrum. It is the graph which represented the sound pressure level with the FFT power spectrum.

Explanation of symbols

10 Oil seal (sealing device)
18 Seal lip 20 Oil side inclined surface (fluid side inclined surface)
23 Atmospheric side inclined surface (sliding contact surface)
30 Projection 36 Rotating shaft 36A Seal surface

Claims (2)

In a sealing device having an annular seal lip having an inner periphery with a sliding contact surface slidably contacting a sealing surface of a mating member, and sealing a fluid by contact between the sealing surface and the sliding contact surface,
A plurality of protrusions are formed on the sliding contact surface at intervals in the sliding direction. The protrusions extend perpendicular to the sliding direction and have a length in the direction perpendicular to the sliding direction. A sealing device, wherein the sealing device is formed larger than a width in a sliding direction.   An inner peripheral surface of the seal lip is formed in a tapered shape toward the radially inner side, and a fluid-side inclined surface and an atmosphere-side inclined surface that are inclined in directions opposite to each other with the tip edge as a boundary are adjacent to each other. The atmosphere-side inclined surface constitutes the sliding contact surface, and the protrusion is formed at a position away from the tip edge of the boundary between the fluid-side inclined surface and the atmosphere-side inclined surface. The sealing device according to claim 1.

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