JP2009144822A - Oil seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil seal 1 including a seal lip 5 slidably coming into close contact with a peripheral face of a rotary shaft 22 and a helical groove 7 in a sliding face 6 of the seal lip 5, which suppresses the occurrence of static leakage and exhibits pumping performance by the helical groove 7 to the maximum. <P>SOLUTION: A helical groove 7 is provided over the whole axial length of a sliding face 6 of a seal lip 5 so as to communicate one end and the other end to an oil chamber O and to an external space, respectively. An oil sump 8 for storing oil flowing along the helical groove 7 from the oil chamber O is provided to an external space side of the seal lip 5. In the oil sump 8, an oil stopping lip 9 having a shape directing a lip end 9c toward the oil chamber O side functions to store oil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oil seal which is a kind of sealing device. The oil seal of the present invention is used, for example, as an oil seal for automobiles (engines) or as an oil seal for general-purpose machines.

  Conventionally, as shown in FIG. 2, an oil seal having a seal lip 52 slidably in close contact with the peripheral surface of the rotary shaft 51 and a spiral groove 54 provided on the slide surface 53 of the seal lip 52 is known. (See FIG. 9 of Patent Document 1). The spiral groove 54 has a function of pumping when the shaft rotates and pushing back the oil entering the sliding portion from the oil chamber O to the oil chamber O. However, the spiral direction should be set oppositely. In some cases, the oil sucks oil to lubricate the sliding portion.

  However, in the oil seal in which the spiral groove 54 is provided on the sliding surface 53 of the seal lip 52 as described above, oil leakage (so-called static leakage) may occur through the spiral groove 54 when the shaft rotation is stationary. is there.

  Therefore, as a countermeasure, for example, a smooth peripheral surface not formed with a groove is provided in a portion on the oil chamber side of the spiral groove on the seal lip sliding surface (see Patent Document 1), or the groove provided there is a groove width. (Refer to Patent Document 2), or conversely, a smooth peripheral surface not formed with a groove is provided at a portion of the spiral groove on the atmosphere side of the spiral groove on the sliding surface of the seal lip (see Patent Document 3). Means have been devised.

  However, when a smooth peripheral surface is provided on a part of the sliding surface of the seal lip in this way, the proportion of the spiral groove is reduced by this amount, so that the pumping ability (oil pushing back ability or suction ability) is lowered. . Further, when a smooth peripheral surface is provided at a portion of the spiral groove on the atmosphere side, the smooth peripheral surface is likely to be insufficiently lubricated, so that the sliding torque increases.

  As another countermeasure, there is means for providing a weir (seal dam) in a part of the spiral groove (see Patent Document 4), and this countermeasure is excellent in this respect because it is not necessary to set a smooth peripheral surface. ing.

  However, in this type, since the spiral groove becomes discontinuous at the dam part and affects the pumping capacity, it is usually possible to form only a dam that does not significantly affect the pumping capacity, and thus completely It is often difficult to suppress static leakage.

JP 2001-165327 A JP-A-7-332501 JP 2005-9584 A JP-A-2005-276991

  In view of the above, the present invention has a seal lip that is slidably in close contact with the peripheral surface of the rotating shaft, and a static leak occurs in an oil seal having a spiral groove on the sliding surface of the seal lip. An object of the present invention is to provide an oil seal that can effectively suppress the pumping and that can maximize the pumping ability of the spiral groove.

  In order to achieve the above object, an oil seal according to claim 1 of the present invention is attached to the inner periphery of a shaft hole of a seal housing, and the seal lip is slidably brought into close contact with the peripheral surface of the rotating shaft so that the oil in the oil chamber Is an oil seal that suppresses leakage to the external space, and the sliding surface of the seal lip is provided with a spiral groove, and one end of the spiral groove is the oil seal. It is provided over the entire axial length of the sliding surface of the seal lip so as to communicate with the chamber and the other end thereof communicate with the external space, and stores the oil traveling from the oil chamber through the spiral groove. An oil reservoir is provided on the outer space side of the seal lip, and the oil reservoir has a structure in which an oil retaining lip having a lip end directed toward the oil chamber stores the oil. It is an feature.

  The oil seal according to claim 2 of the present invention is the oil seal according to claim 1, wherein the oil stop lip is slidably in close contact with the peripheral surface of the rotating shaft with a smaller pressing force than the seal lip. It is characterized by.

  An oil seal according to a third aspect of the present invention is the oil seal according to the first aspect, wherein the oil retaining lip is not in contact with the rotating shaft and has a minute radial gap between the rotating shaft and the oil sealing lip. Is set.

  In the oil seal of the present invention having the above configuration, the spiral groove is provided over the entire axial length of the seal lip sliding surface so as to communicate with the oil chamber at one end and communicate with the external space at the other end. For this reason, the spiral groove is provided to the maximum extent in the region, so that the pumping ability by the spiral groove is maximized. The pumping ability includes an oil pushing back ability and a sucking ability depending on the direction of the spiral, and both are included in the present invention.

  In addition, since the oil reservoir that stores the oil traveling from the oil chamber through the spiral groove is provided on the outer space side of the seal lip, the oil is stored in the oil reservoir and does not leak, so Leakage is suppressed.

  Since the oil stop lip is a new configuration according to the present invention, there is a concern about the increase in the sliding torque due to the provision of the oil stop lip. However, as described in claim 2, the oil stop lip can be rotated with a smaller pressing force than the seal lip. By closely slidably contacting the peripheral surface of the shaft, an increase in torque can be suppressed as much as possible. Further, when a small radial gap is set between the rotary shaft and the rotary shaft, the increase in torque can be completely suppressed.

  The present invention has the following effects.

  That is, in the present invention, as described above, since the oil reservoir for storing the oil transmitted from the oil chamber through the spiral groove is provided on the outer space side of the seal lip, the oil is stored in the oil reservoir. It is stored and does not leak, so stationary leakage is suppressed. Further, since the spiral groove is provided over the entire axial length of the seal lip sliding surface so as to communicate with the oil chamber at one end and communicate with the external space at the other end, the spiral groove is The maximum pumping capacity is provided by the spiral groove. Therefore, in the oil seal having both the seal lip slidably in close contact with the peripheral surface of the rotating shaft and the spiral groove provided on the sliding surface of the seal lip, in accordance with the intended purpose of the present invention, It is possible to provide an oil seal that can effectively suppress the occurrence of static leakage and that can maximize the pumping ability of the spiral groove.

  The oil reservoir has a structure in which the oil retaining lip stores oil, and the oil retaining lip has a shape in which the lip end faces the oil chamber side. Therefore, even if the pressure in the oil reservoir increases, the oil retaining lip is pressed against the peripheral surface of the rotating shaft by the pressure and maintains the sealing action, so that the stored oil does not leak.

  In addition, the oil stop lip is slidably in close contact with the peripheral surface of the rotating shaft with a smaller pressing force than the seal lip, so that an increase in sliding torque can be suppressed as much as possible. By setting a minute radial gap between the rotating shaft and the non-contacting shaft, an increase in sliding torque can be completely suppressed.

The present invention includes the following embodiments.
(1) The present invention is an oil seal in which a spiral slit is provided on the entire main lip sliding surface (up to the lip tip), and has an oil reservoir on the atmosphere side, and the lip tip faces the oil chamber side. An oil stop lip is provided. In this case, the spiral slit may be provided with a weir that does not affect the suction ability.
(2) The oil stop lip may have its tip in contact with the shaft, but is preferably non-contact in terms of sliding torque. When the lip tip is brought into contact, the tightening force and the lip contact width are preferably less than half of the main lip in order to suppress an increase in sliding torque. On the other hand, when the tip is not contacted, oil leakage occurs if there is too much distance between the lip tips, so that the gap between the shafts should be about 0.5 mm or less in consideration of lip inner diameter tolerance and shaft eccentricity. It is preferable.
(3) In the present invention, oil leakage at rest can be prevented without impairing the oil suction capability of the main lip and without causing an excessive increase in sliding torque.

  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 an oil seal 1 according to an embodiment of the present invention. The oil seal 1 is mounted on the inner periphery of the shaft hole of the seal housing 21, and the seal lip 5 is slidably brought into close contact with the peripheral surface of the rotary shaft 22, so that oil (not shown) in the oil chamber O is external space. This is configured as follows. The external space is divided into a space 8 a between the seal lip 5 and the oil stop lip 9 and an atmosphere side space A by providing an oil stop lip 9 described later.

  The oil seal 1 has an oil seal main body 2 in which a metal ring 4 is embedded inside a rubber-like elastic body 3, and a seal lip 5 is provided on the inner peripheral portion of the oil seal main body 2. 5 is provided with a spiral groove 7.

The seal lip 5 is integrally formed with the rubber-like elastic body 3 and extends long from the base end portion 5a to the lip end 5c via the bent portion 5b toward the oil chamber O, and is set on the inner peripheral surface thereof. A spiral groove 7 that is longer in the axial direction than the entire length in the axial direction of the sliding surface 6 is provided (the length of the sliding surface 6 in the axial direction is L ₁ , and the spiral groove 7 is the axial length as _{L 2, L 1 <L 2} ).

  The spiral groove 7 exhibits a function of sucking the oil in the oil chamber O into the groove 7 during the shaft rotation so as to lubricate the sliding surface 6, and one end of the spiral groove 7 is formed on the lip end 5c. The other end reaches the bent portion 5b and communicates with the external space (space 8a).

  An oil reservoir 8 is provided on the outer space side of the seal lip 5 to store the oil that travels from the oil chamber O through the spiral groove 7. The oil reservoir 8 has an oil retaining lip 9 that supplies oil. It has a structure to store.

  The oil stop lip 9 is also integrally formed with the rubber-like elastic body 3, and is provided with a base end portion 9a provided from the atmosphere side end surface (lower surface in the figure) toward the atmosphere side (downward in the figure) of the oil seal main body 2. And a reversing portion 9b having an arc-shaped cross section integrally formed at the distal end of the base end portion 9a, and a lip end 9c integrally formed at the distal end of the reversing portion 9b, and the lip end 9c on the oil chamber O side The shape is directed upward (upward in the figure). Further, as shown in the figure, the oil stop lip 9 is not in contact with the rotary shaft 22, and a minute radial gap c of about 0.5 mm is set between the oil stop lip 9 and the rotary shaft 22.

  The oil reservoir 8 has an annular space 8 a surrounded by the seal lip 5, the oil seal body 2, the oil stop lip 9 and the rotating shaft 22, and the space 8 a has an upper surface (oil oil An annular saucer-shaped recess 8b provided on the chamber O side end surface) is included.

  In the oil seal 1 having the above-described configuration, the oil reservoir 8 that stores the oil transmitted from the oil chamber O through the spiral groove 7 is provided on the outer space side of the seal lip 5, so that the oil is stored in the oil seal 1. It is stored in the part 8 and does not leak into the atmosphere-side space A, and thus stationary leakage is suppressed. Further, since the spiral groove 7 is provided over the entire axial length of the sliding surface 6 of the seal lip 5 so as to communicate with the oil chamber O at one end thereof and communicate with the external space at the other end. The spiral groove 7 is provided as much as possible in the region, so that the pumping ability by the spiral groove 7 is maximized. Accordingly, the oil seal 1 having the seal lip 5 slidably in close contact with the peripheral surface of the rotary shaft 22 and the spiral groove 7 provided on the slide surface 6 of the seal lip 5 is combined with the stationary. It is possible to provide the oil seal 1 that can effectively suppress the occurrence of leakage and that can maximize the pumping ability of the spiral groove 7.

  The oil reservoir 8 has a structure in which the oil retaining lip 9 retains oil, and the oil retaining lip 9 has a shape in which the lip end 9c faces the oil chamber O side. Therefore, even if the pressure of the oil reservoir 8 is increased, the oil retaining lip 9 is pressed against the peripheral surface of the rotating shaft 22 by the pressure and maintains the sealing action, so that the stored oil does not leak.

  Further, since the oil retaining lip 9 is not in contact with the rotating shaft 22 and a minute radial gap c is set between the oil retaining lip 9 and the rotating shaft 22, even if the oil retaining lip 9 is provided, a sliding torque is provided. Will not increase.

  In the present invention, the cross-sectional shape of the spiral groove 7 is not particularly limited, and the groove 7 includes notches (slits). The spiral groove 7 may exhibit an oil push-back capability during shaft rotation with the direction of the spiral reversed. The spiral groove 7 may be provided with a weir that does not affect the oil pushing back ability or the suction ability. The spiral groove 7 may be a so-called multiple thread. The oil retaining lip 9 may be slidably in close contact with the peripheral surface of the rotary shaft 22 with a smaller pressing force than the seal lip 5.

Sectional drawing of the principal part of the oil seal which concerns on the Example of this invention Half cut sectional view of oil seal according to conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil seal 2 Oil seal main body 3 Rubber-like elastic body 4 Metal ring 5 Seal lip 5a, 9a Base end part 5b Bending part 5c, 9c Lip end 6 Sliding surface 7 Spiral groove 8 Oil reservoir 8a Space 8b Recess 9 Oil stop lip 9b Reversing part 21 Seal housing 22 Rotating shaft O Oil chamber A Atmosphere side space

Claims (3)

An oil seal that is mounted on the inner periphery of the shaft hole of the seal housing and that prevents the oil in the oil chamber from leaking to the external space when the seal lip slidably contacts the peripheral surface of the rotating shaft. In the oil seal in which a spiral groove is provided on the sliding surface of the lip,
The spiral groove is provided over the entire axial length of the sliding surface of the seal lip so that one end thereof communicates with the oil chamber and the other end communicates with the external space.
An oil reservoir for storing oil that travels along the spiral groove from the oil chamber is provided on the outer space side of the seal lip,
The oil reservoir has a structure in which an oil retaining lip having a shape with a lip end directed toward the oil chamber stores the oil. The oil seal according to claim 1,
An oil seal characterized in that the oil stop lip is slidably in close contact with the peripheral surface of the rotating shaft with a smaller pressing force than the seal lip. The oil seal according to claim 1,
The oil stop lip is non-contact with the rotary shaft, and a minute radial gap is set between the oil stop lip and the rotary shaft.

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