JP2013087860A - Oil seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil seal with which the secure sealing performance can be obtained easily.SOLUTION: A seal lip 32 comprises: a first seal face 33 for preventing leak of a sealed fluid when a revolving body S is stopped; and a second seal face 34 which is provided together at a sealed side rather than the first seal face 33 for preventing the leak of the sealed fluid when the revolving body S is rotated. Furthermore, a plurality of screws 40 are provided on a front side of a resin layer 39 of the second seal face 34, and a garter spring 42 is provided on a back side of a lip distal end 37 of the second seal face 34. Moreover, regarding the garter spring 42, the position of the center of a coil diameter of the garter spring 42 in a seal width direction under a mounted state is located between the position of a lip distal end 36 of the first seal face 33 in the seal width direction and the position of the lip distal end 37 of the second seal face 34 in the seal width direction.

Description

  The present invention relates to an oil seal, and more particularly to an oil seal in which a resin layer is provided on a seal surface of a seal lip.

  Conventionally, an oil seal is known as a kind of sealing device for preventing leakage of a sealing fluid to be sealed such as lubricating oil or hydraulic oil. As one type of this oil seal, a resin layer formed of a fluororesin excellent in low friction, low wear, and chemical resistance is provided on at least the seal surface of a seal lip formed of a rubber-like elastic body such as rubber. There are some (see, for example, Patent Document 1).

  The oil seal provided with this resin layer has low friction compared to a seal lip formed only by a rubber-like elastic body without a resin layer, and thus can reduce the torque of the rotating body, but has low elasticity. Therefore, there was a problem that the sealing performance was poor.

  Therefore, the present applicant has proposed an oil seal with improved sealing performance (see, for example, Patent Document 2).

  The oil seal includes a first seal lip for preventing leakage of a sealing fluid when the rotating shaft serving as a rotating body is stopped, and the tip of the first seal lip extending toward the sealing side and sealed when the rotating shaft rotates. A pump having a second seal lip for preventing fluid leakage, and on the seal surface of the second seal lip, a pump that pushes back the sealing fluid that attempts to leak from the seal side to the first seal lip side. It is set as the structure provided with the some screw | thread connected to the lip tip for exhibiting a function.

  And while ensuring the sealing performance at the time of rotation of a rotating shaft with a 2nd seal lip, the sealing performance can be improved by ensuring the sealing performance at the time of a stop of a rotating shaft with a 1st seal lip. ing.

JP 2003-185028 A JP 2011-174570 A (FIG. 5)

  However, in the conventional oil seal having two seal lips, the second seal lip extends from the tip of the first seal lip toward the sealing side, and the first seal lip disposed on the atmosphere side Since the tightening force of the two seal lips is held by the garter spring arranged on the back surface, the seal lip is forced to be applied to the lip tip of the first seal lip and the lip tip of the second seal lip. In other words, it was not possible to disperse in a well-balanced manner, and there was a problem that sealing performance was inferior.

  Therefore, there is a demand for an oil seal that can easily provide reliable sealing performance.

  This invention is made | formed in view of this point, and provides the oil seal which can acquire reliable sealing performance easily.

  In order to achieve the above-mentioned object, the oil seal according to claim 1 of the present invention is characterized in that an annular seal formed by a rubber-like elastic body is mounted between a rotating body and a stationary body. The seal lip has a resin layer on at least the seal surface of the seal lip, and the tip of the lip of the seal surface is slidably in contact with the surface of the rotating body. The seal lip includes a first seal surface for preventing leakage of a sealing fluid when the rotating body is stopped, and a seal side of the first seal surface. And a second seal surface for preventing leakage of the sealing fluid, a plurality of screws are provided on the surface of the resin layer of the second seal surface, and a garter is provided on the back surface of the seal lip. Spring is arranged When the garter spring is mounted, the center of the coil diameter of the garter spring in the seal width direction is the position in the seal width direction of the lip tip of the first seal surface and the lip tip of the second seal surface. It is in the point arrange | positioned between the positions in the seal width direction.

  In addition, by adopting such a configuration, the sealing force of the seal lip can be distributed in a balanced manner at two locations of the lip tip of the first seal surface and the lip tip of the second seal surface. Sex can be easily obtained.

  According to the oil seal of the present invention, the sealing force of the seal lip can be distributed in a balanced manner between the lip tip of the first seal surface and the lip tip of the second seal surface, so that reliable sealing performance can be easily obtained. Excellent effects such as being able to.

The schematic sectional drawing in the free state of the embodiment of the oil seal concerning the present invention The same figure as FIG. 1 which shows the mounting state of the oil seal of FIG.

  The present invention will be described below with reference to embodiments shown in the drawings.

  As shown in FIGS. 1 and 2, an oil seal 10 as a sealing device of the present embodiment is mounted between a rotating shaft S as a rotating body and a housing H as a stationary body, and the rotating shaft S and the housing H A so-called inner peripheral lip type that can seal an annular seal gap G between the two is illustrated.

  The oil seal 10 according to the present embodiment is formed by integrally baking a seal body 30 formed of a rubber-like elastic body such as rubber on a reinforcing ring 20 formed of metal or resin.

  The reinforcing ring 20 has a cylindrical portion 21 and an inward flange portion 22 formed to extend from the end of the atmospheric side AS shown on the left side of the cylindrical portion 21 in FIG. As a whole, a sealing-side OS on which a sealing fluid such as lubricating oil or hydraulic oil shown on the right side of FIG. 1 is present is formed in an annular shape having a substantially L-shaped cross section.

  The seal body 30 includes an outer peripheral seal portion 31 fitted to the inner surface of the housing H, and a seal lip 32 that contacts the rotating shaft S with an appropriate tightening allowance. The outer peripheral seal portion 31 is formed so as to cover the outer periphery of the cylindrical portion 21 of the reinforcing ring 20. In addition, you may provide the cyclic | annular dust lip formed so that it may reduce in diameter gradually from the inner peripheral part of the reinforcement ring 20 toward air | atmosphere side AS as needed, such as a design concept.

  The seal lip 32 has a first seal surface 33 and a second seal surface 34. That is, the seal lip 32 of the present embodiment includes two seal surfaces 33 and 34 arranged in parallel along the axial direction.

  The first seal surface 33 is for preventing leakage of the sealing fluid when the rotating shaft S is stopped, and is formed in an annular shape so as to gradually reduce the diameter toward the sealing side OS. The position of the small diameter of the first seal surface 33 is a lip tip 36 (hereinafter referred to as the first lip tip 36).

  The second seal surface 34 is for preventing leakage of the sealing fluid during rotation of the rotary shaft S, and is juxtaposed to the sealing side OS shown on the right side of FIG. . The second seal surface 34 extends from the first lip tip 36 toward the sealing side OS in a substantially cylindrical shape, and the connection surface portion 34a extends from the right edge of FIG. 1 toward the sealing side OS. And a sealing surface portion 34b formed in an annular shape so as to be gradually reduced in diameter. Moreover, the length shown to the left-right direction of each of the connection surface part 34a and the seal surface part 34b may be equal, and may differ. In the present embodiment, the connecting surface portion 34a and the sealing surface portion 34b are formed to have the same length. The small diameter position of the seal surface portion 34b, and hence the small diameter position of the second seal surface 34, is a lip tip 37 (hereinafter referred to as a second lip tip 37). Further, the second lip tip 37 in the free state shown in FIG. 1 is formed to have a smaller diameter than the first lip tip 36. In the mounting state shown in FIG. 2 in which the oil seal 10 of the present embodiment is mounted in the seal gap G between the rotating shaft S and the housing H, the first of the connection surface portions 34a of the second seal surface 34 is the first. The portion excluding the connection portion with the lip tip 36 is formed so as to face the rotating shaft S in a non-contact state. Further, the connection surface portion 34a may be an annular curved surface that is convex outward in the radial direction. Further, the inclination angle formed with the rotation axis S of the second seal surface 34 is formed smaller than the inclination angle formed with the rotation axis S of the first seal surface 33. Furthermore, in the present embodiment, the length of the seal surface portion 34b shown in the left-right direction in FIG. 1 is equal to the length of the first seal surface 33 shown in the left-right direction in FIG. Of course, the length of the seal surface portion 34b and the length of the first seal surface 33 may be different.

  The surfaces of the first seal surface 33 and the second seal surface 34 are respectively covered with a resin layer 39 (exaggerated in FIG. 1). The resin layer 39 may be an integrated resin sheet, or may be an integrated resin coating. The resin material can be selected from various resins such as a fluororesin such as polytetrafluoroethylene (PTFE), a polyester resin, and a polyamide resin as required by the design concept. Further, the resin material may be a resin alone, or a glass fiber, carbon fiber, graphite, molybdenum, carbon, etc., alone or in combination of several types, and an appropriate amount as a filler is blended. Also good.

  In the present embodiment, both the first seal surface 33 and the second seal surface 34 provided side by side are covered with the resin layer 39. However, the first seal surface 33 and the second seal surface 34 are provided. Of these, only the sealing surface portion 34 b may be covered with the resin layer 39. In this case, the resin layer 39 of the first seal surface 33 and the resin layer 39 of the seal surface portion 34b of the second seal surface 34 may be made of the same resin material or different resin materials.

  A plurality of screws 40 connected to the second lip tip 37 are provided on the surface of the second seal surface 34, more specifically on the surface of the seal surface portion 34b of the second seal surface 34 (see FIGS. 1 and 2). It is exaggerated.) As is well known, the plurality of screws 40 exhibit a pump function that pushes back a sealing fluid such as lubricating oil (not shown) that is about to leak from the sealing side OS toward the atmosphere side AS when the rotary shaft S rotates. To do. In addition, the pump function is also capable of causing the sealing fluid existing between the first lip tip 36 and the second lip tip 37 to flow to the sealing side OS.

  The screw 40 may be provided so as to protrude from the surface of the seal surface portion 34b or may be provided as a recess. The cross-sectional shape of the screw 40 can be selected from various shapes such as a triangle and a trapezoid. Further, the screw 40 may exhibit a pump function with respect to any one of the forward rotation direction and the reverse rotation direction of the rotation shaft S, or both the forward rotation direction and the reverse rotation direction. In contrast, it may exhibit a pump function.

  The plurality of screws 40 of the present embodiment are formed so as to project in a triangular mountain shape in cross section on the seal surface portion 34 b and to exhibit a pump function by the normal rotation of the rotation shaft S. In addition, since it is the same as that of a conventionally well-known thing about other structures, such as the inclination angle of the some screw | thread 40, height, and a pitch, the detailed description is abbreviate | omitted.

  Further, the plurality of screws 40 may be formed so as to come into contact with the surface of the rotating shaft S at a plurality of locations along the circumferential direction of the rotating shaft S, or continuous with the rotating shaft S over the entire circumference. It may be formed so as to make contact. However, the friction (sliding resistance) with respect to the rotating shaft S, that is, the torque at the time of rotation of the rotating shaft S can be reduced. It is preferable to be formed so as to contact at a plurality of locations along the direction. Of course, the screw 40 can be selected and used from conventionally known various types.

  On the back surface of the seal lip 32, in this embodiment, on the radially outer back surface of the second lip tip 37, an annular spring mounting groove 41 formed in a substantially semicircular cross section that opens radially outward is recessed. In the spring mounting groove 41, a garter spring 42 for holding a radial pressing force between the seal lip 32 and the rotating shaft S is disposed. The garter spring 42 also has a function (tightening adjustment function) that compensates for the tight force of the seal lip 32 on the rotation axis S.

  Here, in the mounting state shown in FIG. 2, the seal lip 32 in the present embodiment applies the tightening force of the seal lip 32 to the first lip tip 36 of the first seal surface 33 and the second lip tip 37 of the second seal surface 34. Are distributed in a well-balanced manner.

  Specifically, the position of the center dc of the coil diameter of the garter spring 42 in the mounted state shown in FIG. 2 in the seal width direction, which is the axial direction shown in the horizontal direction in FIG. 2, is the position of the first lip tip 36 in the seal width direction. And the position of the second lip tip 37 in the seal width direction. That is, the virtual plane including the center dc of the coil diameter of the garter spring 42 in the mounted state is disposed between the virtual plane including the first lip tip 36 in the mounted state and the virtual plane including the second lip 37 in the mounted state. It is set as the structure. In the present embodiment, the position of the center dc of the coil diameter of the garter spring 42 in the free state shown in FIG. 1 in the seal width direction is arranged at a position substantially equal to the position of the second lip tip 37 in the seal width direction. Yes.

  Since the first seal surface 33 is for preventing leakage of the sealing fluid when the rotary shaft S is stopped, the tightening force by the first lip tip 36 is slightly larger than the tightening force by the second lip tip 37. You may form as follows.

  Further, in this embodiment, the position of the free end of the most sealed side OS shown on the right side of FIG. 1 of the seal lip 32 is the outer periphery regardless of whether it is in the free state shown in FIG. 1 or the attached state shown in FIG. The seal portion 31 is disposed on the atmosphere side AS with respect to the end surface located closest to the sealing side OS, and is formed so that the free end of the seal lip 32 does not protrude outside the oil seal 10.

  Next, the operation of the present embodiment having the above-described configuration will be described.

  According to the oil seal 10 of the present embodiment, when the rotary shaft S rotates, the plurality of screws 40 provided on the second seal surface 34 will leak from the sealing side OS to the first seal surface 33 side which is the atmospheric side AS. Since the pumping action of pushing back the sealing fluid to the sealing side OS is exhibited, the sealing performance when the rotating shaft S rotates can be secured.

  Further, according to the oil seal 10 of the present embodiment, when the rotating shaft S is stopped, the sealing fluid on the sealing side OS passes through the second lip tip 37 and exudes toward the first lip tip 36 side. However, the sealing fluid that oozes out toward the first lip tip 36 is sealed when the first lip tip 36 is in close contact with the entire circumference of the outer peripheral surface of the rotary shaft S, and therefore leaks to the atmosphere side AS. In other words, the sealing performance when the rotating shaft S is stopped can be ensured reliably and easily.

  Here, the sealing fluid that has passed through the second lip tip 37 and oozed to the first lip tip 36 side when the rotation shaft S is stopped is applied to the seal surface portion 34b of the second seal surface 34 when the rotation shaft S rotates. By contact with the plurality of formed screws 40, the screw 40 can return to the sealed side OS by the pump function.

  That is, the sealing fluid that has passed through the second lip tip 37 and oozed out toward the first lip tip 36 when the rotating shaft S is stopped exists between the second lip tip 37 and the first lip tip 36. Become. When the rotating shaft S is stopped, the sealing fluid existing between the second lip tip 37 and the first lip tip 36 is returned to the sealing side OS by the pump function of the screw 40 exhibited by the rotation of the rotating shaft S. be able to.

  That is, according to the oil seal 10 of the present embodiment, the second sealing surface 34 shares the sealing performance when the rotating shaft S rotates, and the first sealing surface 33 shares the sealing performance when the rotating shaft S stops. Therefore, it is possible to ensure the sealing performance when the rotating shaft S is stopped and rotated.

  Further, according to the oil seal 10 of the present embodiment, the seal lip 32 includes a first seal surface 33 for preventing leakage of the sealing fluid when the rotary shaft S is stopped, and a seal side closer to the first seal surface 33. A seal width of the center cd of the coil diameter of the garter spring 42 in the mounted state is provided in parallel with the OS and provided with a second seal surface 34 for preventing leakage of the sealing fluid when the rotary shaft S rotates. Since the position in the direction is arranged between the position in the seal width direction of the first lip tip 36 and the position in the seal width direction of the second lip tip 37, a garter spring is disposed on the back surface of the first lip tip. Unlike the conventional oil seal having two seal lips, the tightening force of the seal lip 32 is applied to the two locations of the first lip tip 36 and the second lip tip 37. It can be balanced to a good dispersed. As a result, a reliable sealing property can be easily obtained, and a stable sealing property can be obtained over a long period of time, so that the reliability can be improved.

  Further, according to the oil seal 10 of the present embodiment, the seal lip 32 includes a first seal surface 33 for preventing leakage of the sealing fluid when the rotary shaft S is stopped, and a seal side closer to the first seal surface 33. A second seal surface 34 is provided in parallel with the OS to prevent leakage of the sealing fluid when the rotary shaft S rotates, and a garter spring is disposed on the back surface of the first lip tip. Unlike the conventional oil seal provided with two seal lips, the garter spring 42 is disposed on the back surface of the second lip tip 37, so that the shaft is compared with the conventional oil seal provided with two seal lips. Since the seal width, which is the dimension in the direction, can be reduced, the size and weight can be reduced.

  The oil seal 10 of the present embodiment is fixed to the inner peripheral surface of the housing H and is in sliding contact with the outer periphery of the rotary shaft S. However, the oil seal 10 is fixed to the outer peripheral surface of the rotary shaft S and It can be set as the structure which carries out sliding contact to a surrounding surface. And by setting it as such a structure, there can exist an effect equivalent to this embodiment or an equivalent.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

DESCRIPTION OF SYMBOLS 10 Oil seal 20 Reinforcement ring 21 Cylindrical part 22 Flange part 30 Seal main body 31 Outer peripheral seal part 32 Seal lip 33 First seal surface 34 Second seal surface 34a Connection surface part 34b Seal surface part 36 First lip tip 37 Second lip tip 39 Resin Layer 40 Screw 41 Mounting groove 42 Garter spring AS Atmosphere side OS Sealed side H Housing S Rotating shaft G Seal gap dc (Girder spring coil diameter) center

Claims (1)

The seal lip is mounted between the rotating body and the stationary body, and has an annular seal lip formed of a rubber-like elastic body. A resin layer is provided on at least the seal surface of the seal lip, and the seal An oil seal formed so that the lip end of the surface is slidably in close contact with the surface of the rotating body,
The seal lip is arranged in parallel with a first seal surface for preventing leakage of a sealing fluid when the rotating body is stopped, and a sealing side from the first seal surface, thereby preventing leakage of the sealing fluid when the rotating body is rotated. A second sealing surface for
A plurality of screws are provided on the surface of the resin layer of the second seal surface,
A garter spring is disposed on the back of the seal lip,
When the garter spring is mounted, the center position of the coil diameter of the garter spring in the seal width direction is the position in the seal width direction of the lip tip of the first seal surface and the seal width of the lip tip of the second seal surface. An oil seal, which is arranged between a position in a direction.

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