Sealing device

Abstract

To provide a sealing device capable of suppressing leakage of a sealing target even when the sealing device is used for a shaft that rotates at high speed both in a normal rotating direction and in a reverse rotating direction.SOLUTION: A sealing device 1 includes a reinforcement ring 10 and an elastic body part 20. A lip tip part 22 of a seal lip 21 of the elastic body part 20 includes a sealing side surface 24 and an atmosphere side surface 23 connected via a lip tip 22a. A plurality of projecting structure 2 are provided side by side in the circumferential direction on the atmosphere side surface 23. The projecting structure 2 includes a first projection 31 and a second projection 32 adjacent to each other in the circumferential direction. The first projection 31 is a projection for returning a sealing target leaked out when a rotating shaft rotates in a normal rotating direction to the sealing target side by using a pump action. The second projection 32 is a projection for returning the sealing target leaked out when the rotating shaft rotates in a reverse rotating direction to the sealing target side by using the pump action.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sealing device. [Background technology]

[0002] In recent years, there has been a trend in electric vehicles to increase the rotation speed of the motor shaft in order to make the drive unit smaller and lighter. Also, due to the structure of electric vehicles, the direction of rotation of the motor reverses when moving forward and backward.

[0003] Oil seals have been used as sealing devices in automobiles, general-purpose machines, and the like to seal the gap between a rotating shaft and a through-hole in a housing through which the rotating shaft passes. Oil seals aim to prevent leakage of oil, which is the object of sealing, from the sealed object side where the sealed object is located to the atmosphere side. Some conventional oil seals have multiple equally spaced threaded protrusions that create an airflow from the atmosphere side toward the sealed object side, exerting a pumping action to push back, toward the sealed object, oil droplets that leak over the lip tip into the atmosphere when the rotating shaft rotates at high speed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3278349 Summary of the Invention [Problem to be solved by the invention]

[0005] When conventional oil seals are used on rotating shafts that rotate in both forward and reverse directions, such as the motor shaft of an electric vehicle, the thread projections may not pump oil from the atmosphere to the sealed object when the rotating shaft rotates in the reverse direction at high speed. As a result, when the rotating shaft rotates in the reverse direction at high speed, the sealed object, such as oil, may leak along the thread projections into the atmosphere.

[0006] Thus, there has been a demand for a sealing device with a structure that can prevent leakage of a sealed material, such as oil, even when used on a shaft that rotates at high speed in both the forward and reverse directions.

[0007] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a sealing device that can suppress leakage of a sealed object even when used on a shaft that rotates at high speed in both the forward and reverse rotation directions. [Means for solving the problem]

[0008] In order to achieve the above object, a sealing device according to the present invention is a sealing device used for a rotating shaft that rotates in one direction and the other direction, and comprises: an annular reinforcing ring about the axis; and an annular elastic body portion about the axis that has a seal lip and is formed from an elastic body attached to the reinforcing ring, the seal lip having a lip tip portion that is an annular portion that convex toward the axis, the lip tip portion having a sealing side that is an annular surface facing the sealed object and an air side that is an annular surface facing the atmosphere, which are connected via the lip tip, and the air side has a plurality of protrusion structures arranged circumferentially, the protrusion structures having first and second protrusions adjacent to each other in the circumferential direction, the first protrusions being protrusions that return leaking material from the sealed object to the sealed object by a pumping action when the rotating shaft rotates in the one direction, and the second protrusions being protrusions that return leaking material from the sealed object to the sealed object by a pumping action when the rotating shaft rotates in the other direction.

[0009] In a sealing device according to one embodiment of the present invention, the first protrusion extends from the sealed object side toward the atmosphere side, tilted in the other circumferential direction, and the second protrusion extends from the sealed object side toward the atmosphere side, tilted in one circumferential direction.

[0010] In the sealing device according to one aspect of the present invention, in the projection structure, the end of the first projection on the atmosphere side and the end of the second projection on the atmosphere side are connected to each other.

[0011] In a sealing device according to one embodiment of the present invention, the circumferential width between the atmospheric side end of the first protrusion and the atmospheric side end of the second protrusion in the protrusion structure is narrower than the circumferential width between two of the protrusion structures that are adjacent to each other in the circumferential direction.

[0012] In a sealing device according to one embodiment of the present invention, the circumferential width between the atmospheric side end of the first protrusion and the atmospheric side end of the second protrusion in the protrusion structure is such that, when the rotating shaft rotates, a flow path can be formed between the first protrusion and the second protrusion to return the sealed object to the sealed object side.

[0013] In the sealing device according to one aspect of the present invention, in the projection structure, the first projection and the second projection extend from the lip tip toward the atmosphere side.

[0014] In a sealing device according to one embodiment of the present invention, the plurality of protrusion structures include a plurality of first protrusion structures and a plurality of second protrusion structures, and the plurality of second protrusion structures are arranged so that the ends of the plurality of second protrusion structures facing the sealed object are closer to the atmosphere in the axial direction than the ends of the plurality of first protrusion structures facing the sealed object, and are also arranged between adjacent first protrusion structures in the circumferential direction.

[0015] In a sealing device according to one embodiment of the present invention, the height of the first protrusion and the second protrusion of the second protrusion structure from the atmospheric side is greater than the height of the first protrusion and the second protrusion of the first protrusion structure from the atmospheric side.

[0016] In a sealing device according to one embodiment of the present invention, the plurality of protrusion structures include a plurality of third protrusion structures, which are arranged such that the ends of the plurality of third protrusion structures facing the sealed object are closer to the atmosphere in the axial direction than the ends of the plurality of second protrusion structures facing the sealed object, and which are also arranged between adjacent second protrusion structures among the plurality of second protrusion structures in the circumferential direction.

[0017] In a sealing device according to one embodiment of the present invention, the height of the first protrusion and the second protrusion of the third protrusion structure from the atmospheric side is greater than the height of the first protrusion and the second protrusion of the second protrusion structure from the atmospheric side.

[0018] In a sealing device according to one embodiment of the present invention, the protrusion structure has a third protrusion extending from the sealed object side toward the atmosphere side at an angle to the other side in the circumferential direction, and the third protrusion is connected to the atmosphere side end of the first protrusion. [Effects of the Invention]

[0019] The sealing device according to the present invention can suppress leakage of the sealed object even when used on a shaft that rotates at high speed in both the forward and reverse directions. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a sealing device according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged cross-sectional view showing one side of the cross-section axis shown in FIG. 1. FIG. [Figure 3] FIG. 2 is a partially enlarged view of the sealing device shown in FIG. [Figure 4] 4 is a cross-sectional view showing the shape of a cross section perpendicular to the direction in which the primary projections and the secondary projections extend. FIG. [Figure 5] 2 is a partially enlarged cross-sectional view of a first projection and a second projection of the sealing device shown in FIG. 1, viewed in the circumferential direction. FIG. [Figure 6]1. FIG. 4 is a partially enlarged cross-sectional view of a modified example of the first projection and the second projection of the sealing device shown in FIG. 1, viewed in the circumferential direction. [Figure 7] FIG. 2 is a partial cross-sectional view for explaining a state in which the sealing device shown in FIG. 1 is used. [Figure 8] 10A and 10B are diagrams for explaining the function of the protrusion structure. [Figure 9] 10A and 10B are diagrams showing modified examples of the protrusion structure. [Figure 10] 10A and 10B are diagrams showing protrusion structures according to other modified examples of the protrusion structure. [Figure 11] 10A and 10B are diagrams showing protrusion structures according to other modified examples of the protrusion structure. [Figure 12] FIG. 5 is a cross-sectional view showing a schematic configuration of a sealing device according to a second embodiment of the present invention. [Figure 13] FIG. 13 is a partial enlarged view of the sealing device shown in FIG. [Figure 14] 1 is a schematic diagram showing an example of a drive system to which a sealing device according to the present invention is applied; DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the drawings, not all of the components are labeled with reference numerals, and some of the components may be omitted.

[0022] FIG. 1 is a cross-sectional view showing a schematic configuration of a sealing device 1 according to a first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view showing one side of the cross-section shown in FIG. 1 with respect to an axis x. Also, FIG. 3 is a partially enlarged view of the sealing device 1. The sealing device 1 according to the first embodiment of the present invention is a sealing device used for a rotating shaft that rotates in one direction, which is a forward rotation direction, and the other direction, which is a reverse rotation direction. As will be described later, when attached to an application object and in use, the sealing device 1 contacts the outer peripheral surface of the rotating shaft to seal the object in a space to be sealed. The sealing device 1 is used, for example, in an electric vehicle motor to seal the gap between an output shaft serving as a rotating shaft and a housing. However, the application of the sealing device 1 is not limited to such an electric vehicle motor.

[0023] As shown in FIGS. 1 to 3 , the sealing device 1 includes a reinforcing ring 10 and an elastic body portion 20. The reinforcing ring 10 is an annular member about the axis x. The elastic body portion 20 is an annular member about the axis x formed from an elastic body attached to the reinforcing ring 10 and includes a seal lip 21. The seal lip 21 includes a lip tip portion 22 that is an annular portion that protrudes toward the axis x. The lip tip portion 22 includes a sealing side surface 24 that is an annular surface facing the sealed object and an air side surface 23 that is an annular surface facing the atmosphere, both of which are connected via the lip tip 22 a. A plurality of protrusion structures 2 are provided on the air side surface 23, arranged in the circumferential direction. The protrusion structure 2 includes a first protrusion 31 and a second protrusion 32 that are adjacent to each other in the circumferential direction. The first protrusion 31 is a protrusion that pumps the sealed object back to the sealed object when the rotating shaft rotates in the forward direction. The second projection 32 is a projection for returning the leaked material to the sealed object by pumping action when the rotary shaft rotates in the reverse direction. The configuration of the sealing device 1 will be specifically described below.

[0024] The axis x is the central axis of the sealing device 1. The sealed object side is the side where the sealed object, such as oil, is intended to be present, and is the side indicated by the arrow a in the direction of the axis x, as shown in Fig. 1. The atmosphere side is the side of the atmosphere, the side where the sealed object is intended not to be present, and is the side indicated by the arrow b in the direction of the axis x, as shown in Fig. 1. The direction perpendicular to the direction of the axis x is the radial direction, and the side approaching the axis x in the radial direction is the inner peripheral side, and the side moving away from the axis x in the radial direction is the outer peripheral side.

[0025] The reinforcing ring 10 is, for example, a circular or approximately circular member with the axis x as its central axis or approximately central axis. As shown in Figures 1 and 2, for example, the reinforcing ring 10 has a cylindrical portion 11 that is a cylindrical part extending along the axis x, and a flange portion 12 that is an annular part that widens from the end of the cylindrical portion 11 on the atmospheric side toward the inner periphery. The reinforcing ring 10 is made of, for example, a metal. Examples of metal materials for the reinforcing ring 10 include stainless steel and SPCC (cold-rolled steel). However, the material of the reinforcing ring 10 is not limited to metal.

[0026] The elastic body portion 20 is attached to the reinforcing ring 10, and as shown in FIGS. 1 and 2, for example, it is attached to the reinforcing ring 10 so as to cover the reinforcing ring 10 from the atmosphere side and the outer periphery side. The elastic body portion 20 is reinforced by the reinforcing ring 10. The elastic body portion 20 is formed from an elastic body as described above. Examples of the elastic body of the elastic body portion 20 include various rubber materials. Examples of various rubber materials include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM). The elastic body portion 20 is, for example, bonded to the reinforcing ring 10.

[0027] As described above, the elastic body portion 20 has the seal lip 21, which has a lip tip portion 22 that is an annular portion on the inner circumferential side that convex toward the axis x. The elastic body portion 20 also has a lip waist portion 25, as shown in FIGS. 1 and 2 . The lip waist portion 25 is an annular portion of the elastic body portion 20 that is located near the inner circumferential end of the flange portion 12 of the reinforcing ring 10. The seal lip 21 is connected to the lip waist portion 25 at its air-side end and extends inward from the lip waist portion 25. The seal lip 21 is disposed opposite the cylindrical portion 11 of the reinforcing ring 10. The elastic body portion 20 also has a dust lip 26. The dust lip 26 extends from the lip waist portion 25 toward the atmosphere side and toward the axis x.

[0028] 1 and 2, the lip tip 22 of the seal lip 21 is, for example, an annular or approximately annular portion with the axis x as its central or approximately central axis, and is formed at the end of the seal lip 21 on the sealed object side. The cross-sectional shape of the lip tip 22 is a wedge shape that is convex toward the inner periphery. The lip tip 22 is formed so that the lip tip 22a on the inner periphery side and the portion nearby contact the outer periphery of the rotating shaft in a usage state described below. More specifically, the interference of the lip tip 22 with respect to the rotating shaft is set so that the lip tip 22 contacts the outer periphery of the rotating shaft over a predetermined width in the direction of the axis x, including the lip tip 22a.

[0029] 1 and 2, the lip tip portion 22 is defined by an annular air side surface 23 on the atmosphere side, which are connected to each other via the lip tip 22a, and an annular sealing side surface 24 on the sealed object side. The air side surface 23 is the surface facing the atmosphere side, and is a conical or approximately conical tapered surface whose diameter increases toward the atmosphere side (direction of arrow b) in the direction of the axis x. The sealing side surface 24 is the surface facing the sealed object side, and is a conical or approximately conical tapered surface whose diameter increases toward the inside (direction of arrow a) in the direction of the axis x.

[0030] The air side surface 23 and the sealed side surface 24 intersect with each other on the small diameter side, and the lip tip 22a is formed at this intersection. The lip tip 22a describes a circle or an approximate circle with the axis x as its center or approximate center in a cross section perpendicular to the axis x, and is the part of the lip tip portion 22 located on the innermost side.

[0031] 1 and 2, a recess 21a is formed in the outer peripheral portion of the seal lip 21 so as to face away from the lip tip portion 22, and a garter spring 27 is fitted into the recess 21a. The garter spring 27 is, for example, a metal spring member, and in a state of use described below, presses the lip tip portion 22 of the seal lip 21 radially inward, applying a predetermined amount of tension to the lip tip portion 22 against the outer peripheral surface of the rotating shaft.

[0032] 1 and 2, the dust lip 26 is a portion that extends from the lip waist portion 25 toward the atmosphere side (in the direction of arrow b) and the inner periphery side toward the axis x. The dust lip 26 prevents foreign matter such as muddy water, sand, and dust from entering from the atmosphere side toward the lip tip portion 22 during use, which will be described later.

[0033] 1 and 2, the elastic body portion 20 has a rear cover 28 and a gasket portion 29. The rear cover 28 is a portion that covers the flange portion 12 of the reinforcing ring 10 from the atmosphere side, and the gasket portion 29 is a portion that covers the cylindrical portion 11 of the reinforcing ring 10 from the outer periphery side. The gasket portion 29 is a portion that fixes the sealing device 1 to a through hole of a member such as a housing through which a rotating shaft passes in an in-use state. When the sealing device 1 is attached to the through hole, the gasket portion 29 is compressed radially between the through hole and the cylindrical portion 11 of the reinforcing ring 10, generating a fitting force that is a radial force. The radial thickness of the gasket portion 29 is set so that a predetermined magnitude of fitting force is generated when the sealing device 1 is attached to the through hole. As described above, the elastic body portion 20 has the seal lip 21, lip waist portion 25, dust lip 26, rear cover 28, and gasket portion 29, and is integrally formed from the same elastic body.

[0034] As described above, a plurality of protrusion structures 2 are arranged in a circumferential direction on the air side surface 23 of the lip tip portion 22. As shown in Figures 1 to 3, in the sealing structure 1, as an example, the plurality of protrusion structures 2 are arranged in a row in the circumferential direction. The plurality of protrusion structures 2 are arranged, for example, along a circle centered on the axis x, and are arranged at equal or approximately equal angular intervals around the axis x. Note that Figure 3 is a view of the elastic body portion 20 as seen from the inner peripheral side, and shows the lip tip portion 22 and a part of its vicinity.

[0035] As shown in Figures 2 and 3, the protrusion structure 2 has a first protrusion 31 and a second protrusion 32. The first protrusion 31 is a threaded protrusion that, when in use, rotates in the forward direction of the rotating shaft, exerts a pumping action, returning the sealed material that has leaked past the lip tip 22a into the atmosphere back to the sealed material. The second protrusion 32 is a threaded protrusion that, when in use, rotates in the reverse direction of the rotating shaft, exerts a pumping action, returning the sealed material that has leaked past the lip tip 22a into the atmosphere back to the sealed material. Furthermore, the first protrusion 31 exerts a pumping action, when in use, rotates in the forward direction of the rotating shaft, returning the sealed material that has leaked along the second protrusion 32 past the lip tip 22a into the atmosphere back to the sealed material. Similarly, in use, the second projections 32 exert a pumping action when the rotating shaft rotates in the reverse direction, returning the sealed material that has leaked along the first projections 31 and past the lip tip 22a into the atmosphere back to the sealed material side. Also, in use, the projection structure 2 temporarily blocks and stores the sealed material that has leaked past the lip contact end 22a into the atmosphere when the rotating shaft rotates.

[0036] 2 and 3, the first protrusion 31 protrudes from the air-side surface 23 and extends obliquely in the reverse rotation direction from the sealed object side toward the air side. In other words, the first protrusion 31 extends obliquely toward the air side, inclined in the reverse rotation direction relative to the lip tip 22a of the lip tip portion 22. Therefore, the outer end 31a of the first protrusion 31, which is the end on the air side, is located farther in the reverse rotation direction in the circumferential direction than the inner end 31b, which is the end on the sealed object side. When the rotating shaft rotates forward in use, the first protrusion 31 generates an airflow along the first protrusion 31 from the atmosphere side toward the sealed object side.

[0037] 2 and 3, the first protrusion 31 extends from the lip tip 22a, and the inner end 31b of the first protrusion 31 is located at the lip tip 22a. Furthermore, as shown in Figures 2 and 3, the first protrusion 31 does not reach the outer edge 23a, which is the air-side edge of the air-side surface 23. The outer end 31a of the first protrusion 31 is located at a position away from the lip tip 22a on the air side by a predetermined distance in the direction of the axis x, and the first protrusion 31 extends from the lip tip 22a on the air surface 23 to a position away from the lip tip 22a in the direction of the axis x.

[0038] FIG. 4 is a cross-sectional view showing the shape of a cross section perpendicular to the extension direction of the first projections 31 (hereinafter also referred to as the cross-sectional shape). As shown in FIG. 4, the first projections 31 are triangular or approximately triangular and protrude toward the inner periphery. Specifically, the cross-sectional shape of the first projections 31 is, for example, an equilateral triangle or approximately equilateral triangle as shown in FIG. 4. The cross-sectional shape of the first projections 31 is not limited to this and may be an isosceles triangle, another triangle, or an approximately triangular shape. Furthermore, the cross-sectional shape of the first projections 31 is not limited to a triangle and may be a rectangle or other polygon, a cross-section whose outline describes an arc or a curved line, a cross-section whose outline describes a line formed by a combination of multiple straight lines, a cross-section whose outline describes a line formed by a combination of one or more curves and one or more straight lines, or the like. The cross-sectional shape of the first projections 31 is preferably a shape that is symmetrical with respect to a line perpendicular to the air-side surface 23, such as an equilateral triangle or an isosceles triangle.

[0039] As shown in FIG. 5, for example, the first protrusions 31 are parallel protrusions, and the height T1 of the first protrusions 31 is constant or approximately constant throughout. FIG. 5 is a partially enlarged sectional view of the first protrusions 31 viewed in the circumferential direction. FIG. 6 is a partially enlarged sectional view of a modified first protrusion 31 viewed in the circumferential direction. For example, as shown in FIG. 6, the first protrusions 31 may be boat-shaped protrusions. In this case, the height T1 of the first protrusions 31 is not constant throughout but increases from the inner end 31b toward the outer end 31a. Alternatively, the height T1 of the first protrusions 31 may increase from the inner end 31b toward the outer end 31a up to a predetermined position and then decrease from this predetermined position. The height T1 of the first protrusions 31 is the amount of protrusion from the air-side surface 23, i.e., the distance from the air-side surface 23 in a direction perpendicular to the air-side surface 23.

[0040] The second protrusions 32 extend obliquely in the opposite direction to the first protrusions 31 and have, for example, the same or substantially the same shape and size as the first protrusions 31. As shown in FIGS. 2 and 3 , the second protrusions 32 protrude from the air-side surface 23 and extend obliquely in the forward rotation direction from the sealed object side toward the air side. That is, the second protrusions 32 extend obliquely toward the air side, obliquely in the forward rotation direction relative to the lip tip 22a of the lip tip portion 22. Therefore, the outer end 32a of the second protrusions 32, which is the end on the air side, is located farther in the forward rotation direction than the inner end 32b, which is the end on the sealed object side. When the rotating shaft rotates in the reverse direction during use, the second protrusions 32 generate an airflow along the second protrusions 32 from the atmosphere side toward the sealed object side.

[0041] 2 and 3, the second protrusion 32 extends from the lip tip 22a, and the inner end 32b of the second protrusion 32 is located at the lip tip 22a. Also, as shown in Figures 2 and 3, the second protrusion 32 does not reach the outer edge 23a of the air-side surface 23. The outer end 32a of the second protrusion 32 is located at a position away from the lip tip 22a on the air side by a predetermined distance in the direction of the axis x, and the second protrusion 32 extends from the lip tip 22a on the air-side surface 23 to a position away from the lip tip 22a in the direction of the axis x.

[0042] As shown in FIG. 4, the cross-sectional shape of the second protrusions 32 is the same or substantially the same as that of the first protrusions 31. Furthermore, as shown in FIG. 5, for example, the second protrusions 32 are parallel protrusions, and the height T2 of the second protrusions 32 is constant or substantially constant throughout. The second protrusions 32 may be, for example, boat-shaped protrusions as shown in FIG. 6. In this case, the height T2 of the second protrusions 32 is not constant throughout but increases from the inner end 32b toward the outer end 32a. Furthermore, the height T2 of the second protrusions 32 may increase from the inner end 32b toward the outer end 32a up to a predetermined position and then decrease from this predetermined position. For example, the shape and size of the second protrusions 32 are the same or substantially the same as those of the first protrusions 31. Furthermore, the height T2 of the second protrusions 32 is the same or substantially the same as the height T1 of the first protrusions 31. The height T2 of the second projections 32 is the amount of protrusion from the air side surface 23, and is the distance from the air side surface 23 in a direction perpendicular to the air side surface 23.

[0043] 2 and 3, in the protrusion structure 2, the outer end 31a of the first protrusion 31 and the outer end 32a of the second protrusion 32 are connected. In other words, the outer end 31a of the first protrusion 31 and the outer end 32a of the second protrusion 32 overlap. In this way, the protrusion structure 2 is a V-shaped protrusion.

[0044] The inner ends 31b of the first protrusions 31 and the inner ends 32b of the second protrusions 32 are located at the lip tips 22a, and in use, the lip tips 22a that contact the rotating shaft are raised from the outer circumferential surface of the rotating shaft near the inner ends 31b of the first protrusions 31 and near the inner ends 32b of the second protrusions 32. The amount of lift of the lip tips 22a from the rotating shaft due to the first protrusions 31 and the second protrusions 32 corresponds to the heights of the first protrusions 31 and the second protrusions 32, and increases as the heights of the first protrusions 31 and the second protrusions 32 increase. Therefore, in use, the contact between the lip tip 22 and the rotating shaft becomes more uniform and stable as the heights T1, T2 of the first protrusions 31 and the second protrusions 32 decrease, and becomes less uniform and unstable as the heights T1, T2 of the first protrusions 31 and the second protrusions 32 increase. Therefore, the heights T1, T2 of the first projection 31 and the second projection 32 are set, for example, so that the sealing device 1 has desired sealing performance.

[0045] When the first protrusions 31 and the second protrusions 32 are parallel protrusions, the lip tip portion 22 wears due to sliding against the rotating shaft, and when the first protrusions 31 and the second protrusions 32 partially wear, the radial distance between the first protrusions 31 and the second protrusions 32 and the outer peripheral surface of the rotating shaft increases, and the pumping action of the first protrusions 31 and the second protrusions 32 may be reduced or eliminated. In contrast, when the first protrusions 31 and the second protrusions 32 are boat-shaped protrusions, even when the lip tip portion 22 wears due to sliding against the rotating shaft and the first protrusions 31 and the second protrusions 32 partially wear, the change in the radial distance between the first protrusions 31 and the second protrusions 32 and the outer peripheral surface of the rotating shaft can be suppressed or prevented. Therefore, when the first protrusions 31 and the second protrusions 32 are boat-shaped protrusions, even when the first protrusions 31 and the second protrusions 32 partially wear, the reduction in the pumping ability of the first protrusions 31 and the second protrusions 32 can be suppressed.

[0046] Next, the operation of the sealing device 1 having the above-mentioned configuration will be described. Fig. 7 is a partial cross-sectional view for explaining the state of use of the sealing device 1. In the state of use, the sealing device 1 is attached to the space between a rotating shaft 50 and a housing 51 having a through hole 52 through which the rotating shaft 50 passes, in order to seal the space between the rotating shaft 50 and the housing 51. The rotating shaft 50 is, for example, the output shaft of a drive motor for an automobile, and the housing 51 is, for example, a cover for the motor.

[0047] As shown in Fig. 7 , in use, the sealing device 1 is press-fitted into a through-hole 52 of a housing 51, and the gasket portion 29 of the elastic body portion 20 is compressed between the housing 51 and the reinforcing ring 10 and is in contact with an inner circumferential surface 52a of the through-hole 52. This provides a seal between the sealing device 1 and the through-hole 52 of the housing 51. Furthermore, the lip tip portion 22 of the seal lip 21 is in slidable contact with an outer circumferential surface 50a of the rotating shaft 50, providing a seal between the sealing device 1 and the rotating shaft 50. Specifically, the lip tip portion 22 is in contact with the outer circumferential surface 50a of the rotating shaft 50 at a contact surface S, which is a portion of the lip tip portion 22 including the lip tip 22a and having a width in the direction of the axis x. This provides a seal against oil, which is the object to be sealed, toward the object to be sealed.

[0048] Furthermore, at least a portion of the first protrusion 31 and the second protrusion 32 of each protrusion structure 2 contacts the outer peripheral surface 50a of the rotating shaft 50. For example, the first protrusion 31 and the second protrusion 32 contact the outer peripheral surface 50a of the rotating shaft 50 at contact surfaces S1 and S2, which are portions continuing from the inner ends 31b and 32b, respectively (see FIG. 8, which will be described later).

[0049] FIG. 8 is a diagram illustrating the function of the protrusion structure 2. FIG. 8 schematically illustrates the protrusion structure 2 in contact with the outer peripheral surface 50a of the rotating shaft 50. In the protrusion structure 2, the first protrusions 31 are inclined toward the atmosphere and in the reverse rotation direction of the rotating shaft 50. Therefore, when the rotating shaft 50 rotates in the forward direction in the above-described usage state, an airflow F1 is generated that flows along the first protrusions 31 from the atmosphere side to the sealed object side, as shown in FIG. 8. This airflow F1 provides a pumping action that acts to return oil droplets that have leaked beyond the contact surface S from the atmosphere side to the sealed object side. Therefore, oil droplets that have leaked beyond the contact surface S of the lip tip portion 22 to the atmosphere side are pushed beyond the contact surface S by the pumping action of the first protrusions 31 back to the sealed object side.

[0050] Meanwhile, in the protrusion structure 2, the second protrusions 32 are provided so as to be inclined toward the atmosphere in the forward rotation direction of the rotating shaft 50. Therefore, when the rotating shaft 50 rotates in the forward rotation direction in the above-described usage state, an airflow F2 is generated that flows along the second protrusions 32 from the sealed object side to the atmosphere side, as shown in FIG. 8 . This airflow F2 may cause oil droplets to be expelled from the sealed object side to the atmosphere side. Here, in the protrusion structure 2, the first protrusions 31, which exert a pumping action that returns oil droplets to the sealed object side when the rotating shaft 50 rotates in the forward rotation direction, are connected to the second protrusions 32 downstream of the airflow F2 generated by the second protrusions 32. Therefore, the oil droplets expelled from the sealed object side to the atmosphere by the airflow F2 are pushed back to the sealed object side by the pumping action of the first protrusions 31.

[0051] In this way, when the rotating shaft 50 rotates in the forward rotation direction, the protrusion structure 2 can return, via the first protrusions 31, oil droplets that leak into the atmosphere beyond the contact surface S of the lip tip portion 22, as well as oil droplets that are released into the atmosphere by the second protrusions 32, back to the sealed object. The higher the rotation speed of the rotating shaft 50, the more oil droplets are released into the atmosphere by the second protrusions 32. As described above, the protrusion structure 2 can return, via the first protrusions 31, oil droplets that are released into the atmosphere by the second protrusions 32, back to the sealed object. Therefore, the protrusion structure 2 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in the forward rotation direction. In this way, the sealing device 1 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in the forward rotation direction. The sealing device 1 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in the forward rotation direction, for example, at a peripheral speed of 50 m / s.

[0052] On the other hand, when the rotating shaft 50 rotates in the reverse direction in the above-described usage state, as shown in Figure 8, in the protrusion structure 2, the first protrusion 31 and the second protrusion 32 act in the opposite manner to when rotating in the forward direction, and the protrusion structure 2 can suppress or prevent oil leakage, just as in the case of rotation in the forward direction.

[0053] In other words, when the rotating shaft 50 rotates in the reverse direction, an airflow F3 is generated that flows from the atmosphere side toward the sealed object side along the second protrusion 32. This airflow F3 provides a pumping action that acts to return oil droplets from the atmosphere side to the sealed object side. Therefore, oil droplets that have leaked beyond the contact surface S of the lip tip 22 toward the atmosphere side are pushed beyond the contact surface S toward the sealed object by the pumping action of the second protrusion 32.

[0054] On the other hand, in the protrusion structure 2, the first protrusions 31 generate an airflow F4 that flows along the first protrusions 31 from the sealed object side to the atmosphere side, as shown in Fig. 8. This airflow F4 may cause oil droplets to be expelled from the sealed object side to the atmosphere side. Here, in the protrusion structure 2, the second protrusions 32, which perform a pumping action to return oil droplets to the sealed object side when the rotating shaft 50 rotates in the reverse direction, are connected to the first protrusions 31 downstream of the airflow F4 generated by the first protrusions 31, and the oil droplets expelled from the sealed object side to the atmosphere side by the airflow F4 are pushed back to the sealed object side by the pumping action of the second protrusions 32.

[0055] In this way, when the rotating shaft 50 rotates in the reverse rotation direction, the protrusion structure 2 can return, by the second protrusions 32, oil droplets that leak into the atmosphere beyond the contact surface S of the lip tip portion 22, as well as oil droplets that are released into the atmosphere by the first protrusions 31, to the sealed object. Therefore, the protrusion structure 2 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in the reverse rotation direction. In this way, the sealing device 1 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in the reverse rotation direction. The sealing device 1 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in the reverse rotation direction, for example, at a peripheral speed of 50 m / s.

[0056] 8, in the protrusion structure 2, the first protrusion 31 and the second protrusion 32 are connected on the atmosphere side to form a V-shaped protrusion, and thus the first protrusion 31 and the second protrusion 32 form a space 2a that is closed on the atmosphere side. Therefore, the protrusion structure 2 can block oil droplets that have leaked into the atmosphere beyond the contact surface S and store them in the space 2a, functioning as a dam against oil droplets that have leaked into the atmosphere. Furthermore, the protrusion structure 2 can return the oil stored in the space 2a beyond the contact surface S to the sealed object side by the pumping action of the airflow F1 or the airflow F3. This action also allows the protrusion structure 2 to suppress or prevent oil leakage.

[0057] As described above, the sealing device 1 according to the first embodiment of the present invention can suppress leakage of the sealed object even when used with a rotating shaft 50 that rotates at high speed in both the forward and reverse rotation directions. In the above description, oil as the sealed object leaks in the form of droplets, but this is one example of the manner in which leakage from the sealed object occurs, and the manner in which leakage from the sealed object occurs is not limited to the form of droplets. For example, the manner in which leakage from the sealed object occurs may be such that the sealed object seeps out from the contact surface S.

[0058] As described above, in the protrusion structure 2, as long as the first protrusion 31 pushes back to the sealed object the oil droplets that have been expelled by the second protrusion 32 beyond the contact surface S to the atmosphere side when the rotating shaft 50 rotates in the forward rotation direction, and the second protrusion 32 pushes back to the sealed object the oil droplets that have been expelled by the first protrusion 31 beyond the contact surface S to the atmosphere side when the rotating shaft 50 rotates in the reverse rotation direction, the first protrusion 31 and the second protrusion 32 do not need to be connected on the atmosphere side.

[0059] 9 is a diagram showing a modified example of the protrusion structure 2. As shown in FIG. 9, the outer ends 31a of the first protrusions 31 and the outer ends 32a of the second protrusions 32 may be spaced apart in the circumferential direction. In this case, in the protrusion structure 2, the circumferential width W1 between the outer ends 31a of the first protrusions 31 and the outer ends 32a of the second protrusions 32 is narrower than, for example, the circumferential width W2 (see FIG. 3) between two protrusion structures 2 adjacent to each other in the circumferential direction. Specifically, for example, the width W1 between the outer ends 31a and 32a is a width that allows flow paths P1, P2 to be formed between the first protrusions 31 and the second protrusions 32, which return leaked oil to the sealed object when the rotating shaft 50 rotates in the forward or reverse rotation direction. Flow path P1, which returns leaked oil to the object to be sealed, is a flow path that returns oil discharged by airflow F2 to the object to be sealed by airflow F1, as shown in Fig. 9, for example, and is a flow path formed by airflow F2 connected to the flow path formed by airflow F1. Also, flow path P2, which returns oil to the object to be sealed, is a flow path that returns oil discharged by airflow F4 to the object to be sealed by airflow F3, as shown in Fig. 9, for example, and is a flow path formed by airflow F4 connected to the flow path formed by airflow F3.

[0060] Next, another modification of the protrusion structure 2 will be described. FIGS. 10 and 11 are diagrams illustrating a protrusion structure 3 according to another modification of the protrusion structure 2. FIG. 10 illustrates the protrusion structure 3 as viewed from the inner circumferential side, and FIG. 11 illustrates the protrusion structure 3 as viewed in the circumferential direction. As illustrated in FIG. 10, the protrusion structure 3 includes a third protrusion 33, which is a boat-shaped protrusion, in addition to the first protrusion 31 and the second protrusion 32 of the protrusion structure 2. The third protrusion 33 is located on the air side of the first protrusion 31 and the second protrusion 32, and the first protrusion 31, the second protrusion 32, and the third protrusion 33 are integrally connected to the third protrusion 33. Specifically, as illustrated in FIG. 10, the third protrusion 33 is connected to the outer end 31a of the first protrusion 31 and extends along the first protrusion 31 toward the air side. The third protrusion 33 extends, for example, parallel or approximately parallel to the first protrusion 31.

[0061] 11, the height T3 of the third projection 33, which is a boat bottom projection, is higher than the height T1 of the first projection 31, and increases from the inner end 33b to the outer end 33a up to a predetermined position and then decreases from this predetermined position. The outer end 33a of the third projection 33 is the end of the third projection 33 facing the sealed object, and the inner end 33b of the third projection 33 is the end of the third projection 33 facing the atmosphere. The cross-sectional shape of the third projection 33 is the same as the cross-sectional shape of the first projection 31.

[0062] Like the first protrusions 31, the third protrusions 33 generate an airflow F5 that flows along the third protrusions 33 from the atmosphere side to the sealed object side when the rotating shaft 50 rotates in the forward rotation direction, thereby exerting a pumping action. The third protrusions 33 are located closer to the atmosphere in the direction of the axis x than the first protrusions 31, and the air side surface 23 of the lip tip 22 expands in diameter toward the atmosphere side in the direction of the axis x. Therefore, when the lip tip 22 wears and the contact surface S overlaps the third protrusion 33, the third protrusions 33 contact the outer peripheral surface 50a of the rotating shaft 50 with a width in the direction of the axis x. Therefore, even if the lip tip 22 wears and the first and second protrusions 31 and 32 wear, the third protrusions 33 contact the outer peripheral surface 50a of the rotating shaft 50, and as the rotating shaft 50 rotates in the forward rotation direction, the third protrusions 33 continue to exert a pumping action that returns leaked oil from the atmosphere side over the contact surface S to the sealed object side. In this way, the protrusion structure 3 can improve the pumping ability of the protrusion structure 2. Furthermore, the protrusion structure 3 can maintain the pumping action for a long time despite the progression of wear of the lip tip portion 22.

[0063] Next, a sealing device 4 according to a second embodiment of the present invention will be described. Fig. 12 is a cross-sectional view showing a schematic configuration of the sealing device 4 according to the second embodiment of the present invention, and Fig. 13 is a partially enlarged view of the sealing device 4. Fig. 13 is a view of the elastic body portion 20 as seen from the inner peripheral side, showing the lip tip portion 22 and a part of its vicinity. The sealing device 4 differs from the above-described sealing device 1 in that it has multiple types of protrusion structures as the protrusion structure. Hereinafter, regarding the configuration of the sealing device 4, descriptions of configurations that are the same as or have similar functions to the sealing device 1 will be omitted, and different configurations will be described.

[0064] 12, the protrusion structure of the sealing device 4 includes three types of protrusion structures. That is, the sealing device 4 has, as protrusion structures, a plurality of first protrusion structures 2, a plurality of second protrusion structures 5, and a plurality of third protrusion structures 6. The plurality of first protrusion structures 2 are the plurality of protrusion structures 2 of the sealing device 1 described above.

[0065] The second protrusion structure 5 and the third protrusion structure 6 have the same or similar shape as the first protrusion structure 2, and when they come into contact with the outer peripheral surface 50a of the rotating shaft 50, they act in the same manner as the protrusion structure 2 of the sealing device 1 described above. For example, when the lip tip portion 22 wears and the contact surface S overlaps the second protrusion structure 5 or the third protrusion structure 6, the second protrusion structure 5 or the third protrusion structure 6 comes into contact with the outer peripheral surface 50a of the rotating shaft 50.

[0066] 12 and 13, the second protrusion structures 5 are arranged in a line in the circumferential direction on the air-side surface 23 of the lip tip portion 22, similar to the first protrusion structures 2. As shown in FIGS. 12 and 13, the second protrusion structures 5 are arranged, for example, along a circle centered on the axis x, and are arranged at equal or approximately equal angular intervals around the axis x. The second protrusion structures 5 are arranged such that their ends facing the sealed object are closer to the atmosphere in the direction of the axis x than the inner ends 31b of the first protrusions 31 and the inner ends 32b of the second protrusions 32, which are the ends facing the sealed object of the first protrusion structures 2. The second protrusion structures 5 are also arranged between two adjacent first protrusion structures 2 in the circumferential direction.

[0067] 12 and 13, the plurality of third protrusion structures 6 are arranged side by side in the circumferential direction on the air side surface 23 of the lip tip portion 22, similar to the plurality of first protrusion structures 2. As shown in FIGS. 12 and 13, the plurality of third protrusion structures 6 are arranged, for example, along a circle centered on the axis x, and are arranged at equal or approximately equal angular intervals around the axis x. The plurality of third protrusion structures 6 are arranged such that the ends of the plurality of third protrusion structures 6 facing the sealed object are closer to the atmosphere in the direction of the axis x than the ends of the plurality of second protrusion structures 5 facing the sealed object, and are each arranged between two adjacent second protrusion structures 5 in the circumferential direction.

[0068] As shown in Figures 12 and 13, the second protrusion structure 5 has a first protrusion 34 and a second protrusion 35 that have the same shape and function as the first protrusion 31 and the second protrusion 32 of the first protrusion structure 2.

[0069] As shown in FIGS. 12 and 13 , the first protrusion 34 protrudes from the air-side surface 23 and extends from the sealed object side toward the atmosphere side at an angle in the counter-rotation direction. The cross-sectional shape of the first protrusion 34 is the same as or substantially the same as the cross-sectional shape of the first protrusion 31 of the first protrusion structure 2 (see FIG. 4 ). The first protrusion 34 is, for example, a boat-shaped protrusion (see FIG. 6 ). That is, the height of the first protrusion 34 is not constant throughout but increases from the inner end 34b toward the outer end 34a. The height of the first protrusion 34, which is a boat-shaped protrusion, may increase from the inner end 34b toward the outer end 34a to a predetermined position and then decrease from this predetermined position. The first protrusion 34 may also be a parallel protrusion (see FIG. 5 ). The inner end 34b and outer end 34a of the first protrusion 34 are the end of the first protrusion 34 facing the sealed object side and the end of the first protrusion 34 facing the atmosphere side, respectively. The height of the primary projections 34 is the amount of projection from the air side surface 23, and is the distance from the air side surface 23 in a direction perpendicular to the air side surface 23.

[0070] The second protrusions 35 are protrusions that extend at an inclination opposite to the first protrusions 34, and may have, for example, the same or substantially the same shape and size as the first protrusions 34. As shown in FIGS. 12 and 13 , the second protrusions 35 protrude from the air-side surface 23 and extend at an inclination in the forward rotation direction from the sealed side toward the air side. The cross-sectional shape of the second protrusions 35 is the same or substantially the same as the cross-sectional shape of the second protrusions 32 of the first protrusion structure 2 (see FIG. 4 ). The second protrusions 35 are, for example, boat-shaped protrusions (see FIG. 6 ). That is, the height of the second protrusions 35 is not constant throughout but increases from the inner end 35b toward the outer end 35a. The height of the second protrusions 35, which are boat-shaped protrusions, may increase from the inner end 35b toward the outer end 35a to a predetermined position and then decrease from this predetermined position. The second protrusions 35 may also be parallel protrusions (see FIG. 5 ). The inner end 35b and outer end 35a of the second projection 35 are the end on the sealed object side and the end on the atmosphere side, respectively, of the second projection 35. The height of the second projection 35 is the amount of protrusion from the atmosphere side surface 23, and is the distance from the atmosphere side surface 23 in a direction perpendicular to the atmosphere side surface 23.

[0071] 12 and 13, in the second protrusion structure 5, the outer end 34a of the first protrusion 34 and the outer end 35a of the second protrusion 35 are connected. In other words, the outer end 34a of the first protrusion 34 and the outer end 35a of the second protrusion 35 overlap. In this way, the protrusion structure 2 is a V-shaped protrusion.

[0072] The inner ends 34b of the first protrusions 34 and the inner ends 35b of the second protrusions 35, which are the ends of the second protrusion structure 5 facing the sealed object, are located closer to the atmosphere in the axial x direction than the inner ends 31b of the first protrusions 31 and the inner ends 32b of the second protrusions 32 of the first protrusion structure 2. For example, as shown in Fig. 11 , the inner ends 34b of the first protrusions 34 and the inner ends 35b of the second protrusions 35 of the second protrusion structure 5 are located closer to the atmosphere in the axial x direction than the inner ends 31b of the first protrusions 31 and the inner ends 32b of the second protrusions 32 of the first protrusion structure 2, and are located closer to the sealed object in the axial x direction than the outer ends 31a of the first protrusions 31 and the outer ends 32a of the second protrusions 32 of the first protrusion structure 2. In addition, the inner end 34b of the first protrusion 34 and the inner end 35b of the second protrusion 35 of the second protrusion structure 5 may be located closer to the atmosphere in the direction of the axis x than the outer end 31a of the first protrusion 31 and the outer end 32a of the second protrusion 32 of the first protrusion structure 2.

[0073] As described above, the second protrusion structure 5 is located closer to the atmosphere in the direction of the axis x than the first protrusion structure 2, and the diameter of the air side surface 23 of the lip tip portion 22 increases toward the atmosphere in the direction of the axis x. Therefore, as shown in Fig. 13 , when the lip tip portion 22 wears and the contact surface S overlaps the multiple second protrusion structures 5, the heights of the first protrusions 34 and the second protrusions 35 of the second protrusion structure 5 are greater than the heights of the first protrusions 31 and the second protrusions 32 of the first protrusion structure 2 so that the first protrusions 34 and the second protrusions 35 have a width in the direction of the axis x and come into contact with the outer circumferential surface 50a of the rotating shaft 50.

[0074] As shown in Figures 12 and 13, the third protrusion structure 6 has a first protrusion 36 and a second protrusion 37 that have the same shape and function as the first protrusion 31 and the second protrusion 32 of the first protrusion structure 2, or the first protrusion 34 and the second protrusion 35 of the second protrusion structure 5.

[0075] As shown in FIGS. 12 and 13 , the first protrusion 36 protrudes from the air-side surface 23 and extends inclined in the counter-rotation direction from the sealed object side toward the atmosphere side. The cross-sectional shape of the first protrusion 36 is the same as or substantially the same as the cross-sectional shape of the first protrusion 31 of the first protrusion structure 2 (see FIG. 4 ). The first protrusion 36 is, for example, a boat-shaped protrusion (see FIG. 6 ). That is, the height of the first protrusion 36 is not constant throughout but increases from the inner end 36 b toward the outer end 36 a. The height of the first protrusion 36, which is a boat-shaped protrusion, may increase from the inner end 36 b toward the outer end 36 a to a predetermined position and then decrease from this predetermined position. The first protrusion 36 may also be a parallel protrusion (see FIG. 5 ). The inner end 36 b and outer end 36 a of the first protrusion 36 are the end of the first protrusion 36 facing the sealed object side and the end of the first protrusion 36 facing the atmosphere side, respectively. The height of the first projections 36 is the amount of projection from the air side surface 23 , and is the distance from the air side surface 23 in a direction perpendicular to the air side surface 23 .

[0076] The second protrusions 37 are protrusions that extend at an inclination opposite to the first protrusions 36 and have, for example, the same or substantially the same shape and size as the first protrusions 36. As shown in FIGS. 12 and 13 , the second protrusions 37 protrude from the air-side surface 23 and extend at an inclination in the forward rotation direction from the sealed side toward the air side. The cross-sectional shape of the second protrusions 37 is the same or substantially the same as the cross-sectional shape of the second protrusions 32 of the first protrusion structure 2 (see FIG. 4 ). The second protrusions 37 are, for example, boat-shaped protrusions (see FIG. 6 ). That is, the height of the second protrusions 37 is not constant throughout but increases from the inner end 37b toward the outer end 37a. The height of the second protrusions 37, which are boat-shaped protrusions, may increase from the inner end 37b toward the outer end 37a to a predetermined position and then decrease from this predetermined position. The second protrusions 37 may also be parallel protrusions (see FIG. 5 ). The inner end 37b and outer end 37a of the second projection 37 are the end on the sealed object side and the end on the atmosphere side, respectively, of the second projection 37. The height of the second projection 37 is the amount of protrusion from the atmosphere side surface 23, and is the distance from the atmosphere side surface 23 in a direction perpendicular to the atmosphere side surface 23.

[0077] 12 and 13, in the third protrusion structure 6, the outer end 36a of the first protrusion 36 and the outer end 37a of the second protrusion 37 are connected. In other words, the outer end 36a of the first protrusion 36 and the outer end 37a of the second protrusion 37 overlap. In this way, the protrusion structure 3 is a V-shaped protrusion.

[0078] The inner ends 36b of the first protrusions 36 and the inner ends 37b of the second protrusions 37, which are the ends of the third protrusion structure 6 facing the sealed object, are located closer to the atmosphere in the axial x direction than the inner ends 34b of the first protrusions 34 and the inner ends 35b of the second protrusions 35 of the second protrusion structure 5. For example, as shown in Fig. 13 , the inner ends 36b of the first protrusions 36 and the inner ends 37b of the second protrusions 37 of the third protrusion structure 6 are located closer to the atmosphere in the axial x direction than the inner ends 34b of the first protrusions 34 and the inner ends 35b of the second protrusions 35 of the second protrusion structure 5, and are located closer to the sealed object in the axial x direction than the outer ends 34a of the first protrusions 34 and the outer ends 35a of the second protrusions 35 of the second protrusion structure 5. The inner ends 36b of the first protrusions 36 and the inner ends 37b of the second protrusions 37 of the third protrusion structure 6 may be located closer to the atmosphere in the direction of the axis x than the outer ends 34a of the first protrusions 34 and the outer ends 35a of the second protrusions 35 of the second protrusion structure 5. Furthermore, as shown in Figures 12 and 13, the multiple third protrusion structures 6 may be arranged so as to overlap the multiple first protrusion structures 2, respectively, when viewed in the direction of the axis x.

[0079] As described above, the third protrusion structure 6 is located closer to the atmosphere in the direction of the axis x than the second protrusion structure 5, and the diameter of the air side surface 23 of the lip tip portion 22 increases toward the atmosphere in the direction of the axis x. Therefore, as shown in FIG. 13 , when the lip tip portion 22 wears and the contact surface S overlaps the multiple third protrusion structures 6, the heights of the first protrusions 36 and the second protrusions 37 of the third protrusion structure 6 are greater than the heights of the first protrusions 34 and the second protrusions 35 of the second protrusion structure 5 so that the first protrusions 36 and the second protrusions 37 have a width in the direction of the axis x and come into contact with the outer circumferential surface 50a of the rotating shaft 50.

[0080] As described above, the sealing device 4 has multiple types of protrusion structures 2, 5, and 6, and the first protrusion structure 2, the second protrusion structure 5, and the third protrusion structure 6 each function in the same manner as the protrusion structure 2 of the sealing device 1 described above depending on the progress of wear of the lip tip portion 22. In other words, even if the wear of the lip tip portion 22 progresses and the first protrusion structure 2 is partially or entirely lost, the second protrusion structure 5 continues to function, and even if the wear of the lip tip portion 22 progresses and the second protrusion structure 5 is partially or entirely lost, the third protrusion structure 6 continues to function. Therefore, even if the wear of the lip tip portion 22 progresses, the sealing device 4 can suppress or prevent oil leakage even when the rotating shaft 50 rotates at high speed in both the forward and reverse directions at a peripheral speed of 50 m / s, for example.

[0081] As described above, the sealing device 4 according to the second embodiment of the present invention can suppress leakage of the sealed object even when used with a rotating shaft 50 that rotates at high speed in both the forward and reverse rotation directions.

[0082] The sealing device 3 does not necessarily have to have the third protrusion structure 6. The sealing structure 3 may also have four or more rows of multiple protrusion structures, such as the first protrusion structure 2, the second protrusion structure 5, and the third protrusion structure 6, repeated on the atmosphere side.

[0083] Next, a drive system to which the sealing device according to the present invention is applied will be described. Fig. 14 is a schematic diagram showing an example of a drive system to which the sealing device according to the present invention is applied. As shown in Fig. 14, a drive system 100 as an example includes a rotating device as a drive power source such as a motor 101, and a transmission 102 that changes the speed of the rotation transmitted from the drive power source and outputs it, and the sealing device 1 or 3 described above is attached to the rotating shaft of the motor 101 or the transmission 102. The drive system 100 is, for example, a drive system in an electric vehicle.

[0084] As shown in FIG. 14 , a drive system 100 includes a motor 101 as a driving force source, and the rotating shaft 50 may include a motor shaft 103, which is a power shaft. In the drive system 100, a sealing device 1 or a sealing device 4 is attached to an axial hole of a housing that serves as a case for the motor 101, and the sealing device 1 or the sealing device 4 comes into contact with the outer circumferential surface of the motor shaft 103. The drive system 100 may also include a transmission 102 that changes the speed of rotation transmitted from the driving force source and outputs the rotation, and the rotating shaft 50 may include at least one of an input shaft 104 and an output shaft 106 of the transmission 102. The sealing device 1 or the sealing device 4 is attached to an axial hole of a housing that serves as a case for the transmission 102, and the sealing device 1 or the sealing device 4 comes into contact with the outer circumferential surfaces of the input shaft 104 and / or the output shaft 106.

[0085] Oil 108, which is the object to be sealed, is sealed inside the housings of the motor 101 and the transmission 102, and the liquid-tightness inside each housing is maintained by sealing device 1 or sealing device 4 provided in each axial hole of the motor shaft 103, input shaft 104, and output shaft 106.

[0086] 14, a motor shaft 103 and an input shaft 104 of the transmission 102 are connected, and the driving force generated by the motor 101 is transmitted to the transmission 102 via the motor shaft 103 and the input shaft 104. The transmission 102 further includes an intermediate shaft 105 that changes the speed of the driving force transmitted from the input shaft 104, and the input shaft 104, the intermediate shaft 105, and the output shaft 106 drive wheels 109 provided on the output shaft 106 via a gear 107.

[0087] The drive system to which the sealing device according to the present invention is applied is not limited to a drive system for an electric vehicle, but may also be, for example, a drive system for a vehicle other than an electric vehicle, or various drive systems for rotating equipment other than a vehicle. In other words, the sealing device according to the present invention can be applied to various drive systems that have a rotating shaft that can rotate forward and backward and transmits driving force by the rotating shaft.

[0088] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0089] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. [Explanation of symbols]

[0090] 1, 4 sealing device, 2 projection structure (first projection structure), 2a space, 3 projection structure, 5 second projection structure, 6 third projection structure, 10 reinforcing ring, 11 cylindrical portion, 12 flange portion, 20 elastic body portion, 21 seal lip, 22 lip tip portion, 22a lip tip portion, 23 air side surface, 23a outer edge, 24 sealing side surface, 25 lip waist portion, 26 dust lip, 27 garter spring, 28 rear cover, 29 gasket portion, 31, 34, 36 first projection, 31a, 34a, 36a outer end, 31b, 35b, 37b inner end, 32, 35, 37 second projection, 32a outer end, 32b inner end, third projection, 33a outer end, 33b inner end, 50 rotating shaft, 50a outer peripheral surface, 51 housing, 52 Through hole, 52a inner surface, 100 drive system, 101 motor, 102 transmission, 103 motor shaft, 104 input shaft, 105 intermediate shaft, 106 output shaft, 107 gear, 108 oil, 109 wheel, F1, F2, F3, F4, F5 air flow, S, S1, S2 contact surface, T1, T2, T3 height, x-axis, W1, W2 width

Claims

1. A sealing device used for a rotating shaft that rotates in one direction and the other direction, a reinforcing ring annularly formed around the axis; an annular elastic body portion having a seal lip and formed around the axis from an elastic body attached to the reinforcing ring; The seal lip has a lip tip portion that is an annular portion that is convex toward the axis, the lip tip portion has a sealing side surface which is an annular surface on the sealed object side and an air side surface which is an annular surface on the air side, the sealing side surface being connected via the lip tip, a plurality of protrusion structures are provided on the air-side surface, aligned in a circumferential direction; the protrusion structure has a first protrusion and a second protrusion adjacent to each other in the circumferential direction, the first protrusion is a protrusion for returning the object to be sealed that leaks when the rotation shaft rotates in the one direction to the object to be sealed by a pumping action, the second protrusion is a protrusion for returning the object to be sealed that leaks when the rotation shaft rotates in the other direction by a pumping action to the side of the object to be sealed. Sealing device.

2. the first protrusion extends from the sealed object side toward the atmosphere side while inclining toward the other side in the circumferential direction, The second protrusion extends from the sealed object side toward the atmosphere side while being inclined to one side in the circumferential direction. The sealing device according to claim 1 .

3. In the protrusion structure, an end of the first protrusion on the atmosphere side and an end of the second protrusion on the atmosphere side are connected to each other. The sealing device according to claim 1 .

4. a circumferential width between an end of the first protrusion on the atmosphere side and an end of the second protrusion on the atmosphere side in the protrusion structure is narrower than a circumferential width between two of the protrusion structures adjacent to each other in the circumferential direction; The sealing device according to claim 1 .

5. In the protrusion structure, a circumferential width between the atmospheric side end of the first protrusion and the atmospheric side end of the second protrusion is a width that allows a flow path to be formed between the first protrusion and the second protrusion, which returns the sealed object to the sealed object side when the rotation shaft rotates. The sealing device according to claim 3 .

6. In the protrusion structure, the first protrusion and the second protrusion extend from the lip tip toward the atmosphere side. The sealing device according to claim 1 .

7. the plurality of protrusion structures includes a plurality of first protrusion structures and a plurality of second protrusion structures; the second protrusion structures are provided such that ends of the second protrusion structures on the sealed object side are closer to the atmosphere in the axial direction than ends of the first protrusion structures on the sealed object side, and are provided between adjacent first protrusion structures of the first protrusion structures in the circumferential direction. The sealing device according to claim 1 .

8. a height of the first protrusion and the second protrusion of the second protrusion structure from the air side surface is greater than a height of the first protrusion and the second protrusion of the first protrusion structure from the air side surface; The sealing device according to claim 7.

9. the plurality of protrusion structures include a plurality of third protrusion structures, the third protrusion structures are provided such that ends of the third protrusion structures on the sealed object side are closer to the atmosphere than ends of the second protrusion structures on the sealed object side in the axial direction, and are provided between adjacent second protrusion structures among the plurality of second protrusion structures in the circumferential direction. The sealing device according to claim 7.

10. a height of the first protrusion and the second protrusion of the third protrusion structure from the air side surface is greater than a height of the first protrusion and the second protrusion of the second protrusion structure from the air side surface; The sealing device according to claim 9.

11. the protrusion structure has a third protrusion extending from the sealed object side toward the atmosphere side while inclining in the other circumferential direction, the third protrusion is connected to the air-side end of the first protrusion; The sealing device according to claim 1 .

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