Sealing device and sealing structure

Abstract

To provide a sealing device which enables improvement of discharge performance of foreign objects, such as muddy water, and to provide a sealing structure.SOLUTION: A sealing device 10 includes: a first member 11 attached to an outer member 2; and a second member 18 attached to an inner member 5 which rotates coaxially with the outer member. The second member includes: a cylindrical part 26 which forms a labyrinth seal R communicating with an external space S2 with a portion which faces the second member in a radial direction of the first member; and a circular-ring part 24 which is provided so as not to protrude to the outer diameter side of an outer peripheral surface of the cylindrical part and in which a plurality of recessed parts 25 which are open on the outer peripheral surface are formed at intervals in a circumferential direction. The recessed parts are provided so as to be open at one axial side relative to one axial side surface 11a and one axial side surface of the outer member, which are located at the exterior space side of the first member, in a state where the sealing device is attached to a bearing device.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, there has been known a sealing device that is attached to an inner member and an outer member and prevents foreign matter such as muddy water from entering an annular space defined by these members. For example, the following Patent Document 1 discloses a combination seal ring with a tone wheel that closes the open end of the space between the peripheral surface of the fixed ring and the peripheral surface of the rotating ring. The tone wheel of this seal ring is configured with a number of notches that open to the outer periphery, and is fixed to the rotating ring part in a state where it protrudes outward from the rotating ring part attached to the rotating ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-229954 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with a seal ring such as that in Patent Document 1, if muddy water or the like enters the seal ring, there is a concern that the discharge of the muddy water or the like may be hindered by the portion that protrudes radially outward beyond the rotating circular portion of the tone wheel.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a sealing device and a sealing structure that can improve the ability to discharge foreign matter such as muddy water. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the sealing device of the present invention is a sealing device comprising a first member attached to an outer member and a second member attached to an inner member which rotates coaxially with the outer member, wherein the second member comprises a cylindrical portion which constitutes a labyrinth seal communicating with an external space through a radially opposing portion of the first member, and a circular ring portion which is arranged so as not to protrude outward beyond the outer peripheral surface of the cylindrical portion and in which a plurality of opening recesses are formed at intervals in the circumferential direction on the outer peripheral surface, and wherein the recesses are arranged so as to open on one axial side surface of the first member which faces the external space and on one axial side of the one axial side surface of the outer member when the sealing device is attached.

[0007] In order to achieve the above-mentioned object, the sealing structure of the present invention is a sealing structure in which a first member is attached to an outer member and a second member is attached to an inner member that rotates coaxially with the outer member, wherein a labyrinth seal communicating with an external space is formed by a cylindrical portion of the second member and a part of the first member that faces it in the radial direction, and a plurality of recesses are formed at intervals in the circumferential direction on the outer peripheral surface of a circular ring portion of the second member that is arranged so as not to protrude outward beyond the outer peripheral surface of the cylindrical portion, and are open on one axial side of the first member that faces the external space and on one axial side of the one axial side of the outer member. Effect of the Invention

[0008] Since the sealing device and the sealing structure of the present invention are configured as described above, the ability to discharge foreign matter such as muddy water can be improved. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic vertical cross-sectional view showing an example of a bearing assembly to which a sealing device according to each embodiment is attached; [Diagram 2] 2 is an enlarged view of a portion X in FIG. 1, and is a schematic vertical sectional view showing a sealing device according to a first embodiment of the present invention. FIG. [Diagram 3] FIG. 2 is a schematic side view of the sealing device as viewed from one axial side. [Figure 4] FIG. 5 is a schematic vertical cross-sectional view showing a sealing device according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic vertical cross-sectional view showing a sealing device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an example of a sealing device and a sealing structure according to the present embodiment will be described with reference to the drawings. Note that in some drawings, some of the detailed reference numerals attached in other drawings are omitted. In addition, in the drawings, the two-dot chain line of the seal portion indicates the shape before elastic deformation. In the following description, the external space side in the axial direction will be described as one axial side, and the annular space side in the axial direction will be described as the other axial side. 1 to 3 are diagrams showing an example of a sealing device and a sealing structure according to a first embodiment, and an example of a bearing device to which the sealing device is attached.

[0011] 2 and 3, the sealing device 10 of this embodiment includes a first member 11 attached to the outer member 2, and a second member 18 attached to the inner member 5 which rotates coaxially with the outer member 2. The second member 18 includes a cylindrical portion 26 which constitutes a labyrinth seal R communicating with the external space S2 together with a radially opposing portion of the first member 11. With this configuration, the labyrinth seal R effectively prevents foreign matter such as muddy water from entering. Moreover, the second member 18 is provided with a circular ring portion 24 that is provided so as not to protrude radially outward beyond the outer circumferential surface of the cylindrical portion 26, and in which a plurality of recesses 25 that open onto the outer circumferential surface are formed at intervals in the circumferential direction. With this configuration, foreign matter such as muddy water that has entered the sealing device 10 is not impeded by the circular ring portion 24 when it passes through the labyrinth seal R and is discharged, as compared with a configuration in which the circular ring portion 24 protrudes radially outward beyond the cylindrical portion 26. Moreover, the centrifugal force generated when the second member 18 rotates together with the inner member 5 causes foreign matter such as muddy water to be shaken off along the wall surface that defines the recesses 25, and can be effectively discharged. In addition, when the second member 18 rotates, an air current is generated that is stirred by the recess 25 and flows toward the outer diameter side. As a result, if the pressure is lower than that inside the labyrinth seal R, even if foreign matter such as muddy water enters the labyrinth seal R, the pressure gradient inside and outside the labyrinth seal R makes it possible to effectively expel the foreign matter. The recess 25 is provided so as to open on one axial side of one axial side surface 11a of the first member 11 facing the external space S2 and one axial side surface 2c of the outer member 2 when the sealing device 10 is attached. With this configuration, foreign matter such as muddy water that is dumped from the recess 25 to the external space S2 can be effectively discharged without being hindered by the first member 11 or the outer member 2.

[0012] The sealing structure of this embodiment is configured such that the first member 11 is attached to the outer member 2, and the second member 18 is attached to the inner member 5 which rotates coaxially with the outer member 2. A labyrinth seal R communicating with the external space S2 is formed by the cylindrical portion 26 of the second member 18 and a portion of the first member 11 which faces it in the radial direction. A plurality of recesses 25 are formed at intervals in the circumferential direction on the outer peripheral surface of the annular portion 24 of the second member 18 which is provided so as not to protrude outward beyond the outer peripheral surface of the cylindrical portion 26, and open on one axial side of one axial side 11a of the first member 11 which faces the external space S2 and one axial side 2c of the outer member 2. With such a configuration, the same effects as those of the sealing device 10 described above can be achieved. The details are explained below.

[0013] FIG. 1 shows a bearing device 1 that supports a wheel (not shown) of a vehicle such as an automobile so as to be rotatable about its axis. The bearing device 1 is generally configured to include an outer ring 2 corresponding to the outer member described above, an inner ring 5 corresponding to the inner member described above, and two rows of rolling elements (balls) 6... interposed between the outer ring 2 and the inner ring 5. The inner ring 5 is configured of a hub ring 3 and an inner ring member 4, and the inner ring member 4 is integrally fitted to the vehicle body side of the hub ring 3. A drive shaft 7 is coaxially spline-fitted to the hub ring 3, and the drive shaft 7 is connected to a drive source (drive transmission part) (not shown) via a constant velocity joint 8. The drive shaft 7 is integrated with the hub ring 3 by a nut 9, and the hub ring 3 is prevented from falling off the drive shaft 7. The inner ring 5 (hub ring 3 and inner ring member 4) is rotatable around an axis L with respect to the outer ring 2, and the outer ring 2 and the inner ring 5 constitute two members that rotate relatively to each other, forming an annular space S1. Within the annular space S1, two rows of rolling elements 6 are held by a retainer 6a, and the raceways 2a of the outer ring 2, the hub ring 3, and the raceways 3a, 4a of the inner ring member 4 are rollably interposed. The hub ring 3 has a cylindrical hub ring body 3b and a hub flange 3d formed to extend outwardly from the hub ring body 3b via a rising base portion 3c, and a wheel is attached and fixed to the hub flange 3d by bolts 3e and nuts (not shown).

[0014] Sealing devices 10, 40 are attached to both axial ends of the annular space S1, between the outer ring 2 and the inner ring member 4 and between the outer ring 2 and the hub wheel 3, to seal both axial ends of the annular space S1. This prevents foreign matter such as muddy water from entering the annular space S1 and prevents lubricant (such as grease) filled in the annular space S1 from leaking out to the outside. The sealing devices 10, 10A, 10B of each embodiment are attached to the end of the annular space S1 on the vehicle body side. Next, the configuration of the sealing device 10 of one embodiment will be described.

[0015] The sealing device 10 is configured by combining a first member 11 and a second member 18. The second member 18 attached to the inner ring 5 (inner ring member 4) includes a slinger member 19 having a cylindrical shape formed by pressing a steel plate such as SPCC or SUS. The slinger member 19 includes a first cylindrical portion 20 extending in the axial direction and fitted to the outer circumferential surface 4b of the inner ring member 4. The slinger member 19 also includes a circular ring portion 21 extending from one axial end of the first cylindrical portion 20 to the outer diameter side. The slinger member 19 also includes a second cylindrical portion 22 extending from the outer diameter end of the circular ring portion 21 to the other axial side.

[0016] The second member 18 in the illustrated example includes an elastic body 23 fixed to the slinger member 19. The elastic body 23 is made of magnetic rubber having magnetism, and is magnetized with N poles and S poles alternately and continuously in the circumferential direction. The elastic body 23 constitutes a magnetic encoder. With such a configuration, the elastic body 23 faces a magnetic sensor G provided on a vehicle body or the like, thereby forming a magnetic encoder that detects the rotation speed of the inner ring 5 and the like. The elastic body 23 includes a circular ring portion 24 that covers one axial surface of the circular ring portion 21 of the slinger member 19. In the illustrated example, the circular ring portion 24 faces the magnetic sensor G. The elastic body 23 also includes a cylindrical portion 26 that extends from the end of the outer diameter side of the circular ring portion 24 to the other axial direction, covers the outer circumferential surface of the second cylindrical portion 22, and wraps around the end face on the other axial direction. The elastic body 23 may be formed of rubber that does not have magnetism, and does not need to constitute a magnetic encoder.

[0017] In this embodiment, the recess 25 is formed in the ring portion 24 of the elastic body 23. With this configuration, the recess 25 is formed in the elastic body 23, so the recess 25 can be easily processed compared to when the ring portion is made of metal or the like. The recess 25 may be open on one axial side surface 24a of the ring portion 24. With this configuration, foreign matter such as muddy water can be prevented from accumulating in the recess 25 compared to when the recess 25 is not open on one axial side surface 24a of the ring portion 24 but is open only to the outer diameter side. The depth dimension of the recess 25 along the radial direction of the elastic body 23 may be less than 1 / 2 of the diameter dimension of the ring portion 24 of the elastic body 23. With this configuration, the detection surface of the magnetic encoder can be effectively enlarged compared to when the depth dimension of the recess 25 is 1 / 2 or more of the diameter dimension of the elastic body 23. In the illustrated example, the depth dimension of the recess 25 is configured to be about 1 / 5 to 1 / 6 of the diameter dimension of the elastic body 23. As shown in FIG. 3, a plurality of recesses 25 are provided on the outer circumferential surface of the circular ring portion 24 of the elastic body 23 at intervals in the circumferential direction.

[0018] The recess 25 in the illustrated example is provided to open on the outer peripheral surface of the circular ring portion 24 of the elastic body 23 and on one axial side surface 24a. The recess 25 is defined by a bottom portion 25a that is approximately parallel to the outer peripheral surface of the elastic body 23, both side wall portions 25b, 25b extending from both circumferential ends of the bottom portion 25a to the outer diameter side, and a side wall portion 25c extending from the end portion on the other axial side of the bottom portion 25a to the outer diameter side. The configuration of the recess 25 is not limited to this, and for example, the both side wall portions 25b, 25b may be formed to be inclined so as to move away from each other as they extend from the inner diameter side to the outer diameter side. In addition, the bottom portion 25a may be formed to be inclined to the outer diameter side as it extends from one axial side to the other axial side, or the bottom portion 25a may be an inclined surface formed by connecting one axial side surface 24a and the outer peripheral surface of the circular ring portion 24. In addition, the bottom portion 25a may be formed as a curved surface that is recessed toward the inner diameter side when viewed from one axial side. The depth dimension of the recess 25 may be equal to or greater than half the diameter dimension of the circular ring portion 24 of the elastic body 23 .

[0019] In Fig. 3, the recesses 25 are provided at equal intervals, but this is not limited thereto. In Fig. 3, the circumferential dimension of the recesses 25 is configured to be approximately the same as the interval between the recesses 25, 25 adjacent in the circumferential direction, but it may be smaller or larger than this. In addition, the number of recesses 25 and the circumferential dimension may be appropriately configured so that the interval between the recesses 25 is smaller than in the illustrated example, or conversely, the number of recesses 25 and the circumferential dimension may be appropriately configured so that the interval between the recesses 25 is larger. The recesses 25 may have any shape, size, and number that can provide the above-mentioned effects.

[0020] The first member 11 attached to the outer ring 2 includes a core portion 12 and a seal portion 15 fixed to the core portion 12. The core portion 12 is cylindrically formed by pressing a steel plate such as SPCC or SUS, and has a generally L-shaped vertical cross section on one side as shown in FIG. 2. The core portion 12 includes a cylindrical portion 13 extending in the axial direction and fitted to the inner peripheral surface 2b of the outer ring 2. The cylindrical portion 13 of the core portion 12 is provided with a core recess 13a recessed toward the inner peripheral side at one end in the axial direction on the outer peripheral surface. The core portion 12 also includes a circular ring portion 14 extending toward the inner diameter side from the other axial end of the cylindrical portion 13.

[0021] The seal portion 15 is made of an elastic body such as a rubber material, and is integrally molded by vulcanization bonding to the core portion 12. The seal portion 15 includes a seal base 16 fixed to the core portion 12. The seal base 16 covers the entire inner peripheral surface of the cylindrical portion 13 of the core portion 12. In the illustrated example, the portion of the seal base 16 covering the entire inner peripheral surface of the cylindrical portion 13 of the core portion 12 faces the cylindrical portion 26 of the elastic body 23 via a gap, forming a labyrinth seal R by a gap extending in the axial direction. In addition, the seal base 16 wraps around the end face on one axial side of the cylindrical portion 13 of the core portion 12 and covers the core recess 13a provided on the outer peripheral surface of the cylindrical portion 13. In the illustrated example, the portion of the seal base 16 covering the end face on one axial side of the cylindrical portion 13 of the core portion 12 has one axial side surface 11a of the first member 11. In addition, an annular protrusion 16a is formed that protrudes from the portion of the seal base 16 that covers the core recess 13a toward the outer diameter side. The annular protrusion 16a is interposed in a compressed state between the inner peripheral surface 2b of the outer ring 2 and the outer peripheral surface of the cylindrical portion 13 of the core portion 12, thereby preventing foreign matter such as muddy water from entering the inside from between the inner peripheral surface 2b of the outer ring 2 and the outer peripheral surface of the cylindrical portion 13 of the core portion 12. The seal base 16 also covers the entire surface of one axial side of the circular ring portion 14 of the core portion 12. The seal base 16 also wraps around the end of the inner diameter side of the circular ring portion 14 of the core portion 12 and covers a part of the other axial side of the circular ring portion 14.

[0022] The seal portion 15 includes a seal lip 17 that is formed by extending from the seal base 16 and elastically contacts the second member 18. With this configuration, foreign matter such as muddy water from the external space S2 can be more effectively prevented from entering the annular space S1. In the illustrated example, the seal portion 15 includes an axial lip 17A, a radial lip 17B, and a grease lip 17C as the seal lip 17. The axial lip 17A extends from the seal base 16 to one side in the axial direction, and has a shape that is inclined toward the outer diameter side as it extends to one side in the axial direction. This axial lip 17A elastically contacts the circular ring portion 21 of the slinger member 19. The radial lip 17B is located on the inner diameter side of the axial lip 17A, extends from the seal base 16 to one side in the axial direction, and has a shape that is inclined toward the inner diameter side as it extends to one side in the axial direction. This radial lip 17B elastically contacts the first cylindrical portion 20 of the slinger member 19. The grease lip 17C is located on the other axial side of the radial lip 17B, extends from the seal base 16 to the other axial side, and is shaped to be inclined toward the inner diameter side as it extends to the other axial side. The grease lip 17C is in elastic contact with the first cylindrical portion 20 of the slinger member 19. With this configuration, it is possible to more effectively prevent the grease filled in the annular space S1 from entering the sealing device 10. Note that the number and shape of the seal lips 17 are not limited to these, and the seal lip 17 may be configured not to contact the slinger member 19.

[0023] The sealing device 10 has a space 27 surrounded by the seal base 16, the axial lip 17A, the circular ring portion 21 of the slinger member 19, and the second cylindrical portion 22. With this configuration, even if foreign matter such as muddy water passes through the labyrinth seal R and enters the sealing device 10, the axial lip 17A prevents the foreign matter from entering the internal space any further, and the foreign matter tends to remain in the space 27. Furthermore, the centrifugal force generated by the rotation of the bearing device 1 makes it easier for the muddy water and other foreign matter to be discharged to the external space S2.

[0024] Next, other embodiments of the sealing device will be described with reference to Fig. 4 and Fig. 5. In the following description of each embodiment, differences from the previously described embodiment will be mainly described, and description of configurations and effects of parts common to the previously described embodiment will be omitted or will be described briefly.

[0025] 4 shows a sealing device 10A and a sealing structure according to the second embodiment. In this embodiment, the second member 18A has a circular ring portion 28 made of metal or resin. The circular ring portion 28 is configured to have a diameter dimension that is approximately the same as the diameter dimension of the circular ring portion 24 of the elastic body 23. In addition, the circular ring portion 28 is configured to have a thickness dimension that is approximately the same as the thickness dimension of the circular ring portion 24 of the elastic body 23. The circular ring portion 28 is provided so as to cover one axial side surface 24Aa of the circular ring portion 24A of the elastic body 23A. The circular ring portion 28 is fixed to the circular ring portion 24A of the elastic body 23A by adhesion or the like, and is provided so as not to protrude radially outward beyond the outer circumferential surface of the cylindrical portion 26A of the elastic body 23A. The circular ring portion 28 has a recess 25A that opens on the outer circumferential surface. The recess 25A is provided so as to penetrate the circular ring portion 28 in the thickness direction and open on both axial side surfaces of the circular ring portion 28. The recess 25A is defined by a bottom portion 25Aa that is approximately parallel to the outer circumferential surface of the circular ring portion 28 and both side wall portions 25Ab, 25Ab that extend from both circumferential ends of the bottom portion 25Aa to the outer diameter side. In addition, the opening on the other axial side of the recess 25A is closed by one axial side surface 24Aa of the circular ring portion 24A of the elastic body 23A. Note that the recess 25A of the circular ring portion 28 may be provided so as to open on one axial side of the one axial side surface 2c of the outer ring 2 and the one axial side surface 11a of the first member 11. In the illustrated example, the circular ring portion 24A of the elastic body 23A is located on the other axial side of the circular ring portion 24 of the elastic body 23 of the first embodiment, and is arranged so that one axial side surface 24Aa is at approximately the same axial position as one axial side surface 11a of the first member 11. If the elastic body 23A constitutes a magnetic encoder, it is preferable that the circular ring portion 28 is a non-magnetic material. The circular ring portion 28 may be configured so that the diameter dimension is smaller than the diameter dimension of the circular ring portion 24 of the elastic body 23, and the thickness dimension may be configured so that the thickness dimension is different from the thickness dimension of the circular ring portion 24 of the elastic body 23.

[0026] FIG. 5 shows a sealing device 10B and a sealing structure according to the third embodiment. In the illustrated example, the diameter of the circular ring portion 24B of the elastic body 23B provided with the recessed portion 25B is configured to be approximately half the diameter of the circular ring portion 21A of the slinger member 19A. The circular ring portion 21A of the slinger member 19A in the illustrated example is configured so that the portion on the outer diameter side from the radial middle portion protrudes to one axial side. The circular ring portion 24B of the elastic body 23B is fixed to the portion of the circular ring portion 21A of the slinger member 19A protruding to one axial side. In this embodiment, the circular ring portion 24B of the elastic body 23B is located on one axial side of the circular ring portion 24 of the elastic body 23 in the first embodiment, and foreign matter such as muddy water that is shaken off from the recessed portion 25B to the external space S2 side can be effectively discharged without being hindered by the first member 11A or the outer member 2. In the illustrated example, the circular ring portion 24B of the elastic body 23B is provided at a position spaced apart on one axial side from one axial side surface 11Aa of the first member 11A by a distance equal to or greater than the thickness of the circular ring portion 24B.

[0027] The depth dimension of the recess 25B in the illustrated example is configured to be approximately the same as the depth dimension of the recess 25 in the first embodiment, but the diameter dimension of the circular ring portion 24B of the elastic body 23B is 1 / 2 or less of the diameter dimension of the circular ring portion 24 of the elastic body 23 in the first embodiment. Therefore, the ratio of the depth dimension of the recess 25B to the diameter dimension of the circular ring portion 24B of the elastic body 23B is larger than that in the first embodiment, and the depth dimension of the recess 25B is about 3 / 10 to 9 / 20 of the diameter dimension of the circular ring portion 24B. In the illustrated example, the elastic body 23B is formed of an elastic body other than magnetic rubber and does not constitute a magnetic encoder, but it may be formed of magnetic rubber and configured as a magnetic encoder facing the magnetic sensor G.

[0028] In the illustrated example, the first member 11A is configured to have two seal lips 17, a radial lip 17B and a grease lip 17C. The sealing device 10B is configured with a space portion 27A surrounded by the radial lip 17B, the first cylindrical portion 20 of the slinger member 19, the annular portion 21A, and the second cylindrical portion 22, and foreign matter such as muddy water can be retained in this space portion 27A.

[0029] The different configurations described in the above embodiments may be modified, rearranged, or combined as necessary. Furthermore, each member is not limited to the above-mentioned configuration. For example, the elastic body may not have an elastic cylindrical portion that covers the outer circumferential surface of the second cylindrical portion of the slinger member. In this case, the labyrinth seal is formed between the second cylindrical portion of the slinger member and the seal member. Furthermore, the slinger member may not have an elastic body. [Explanation of symbols]

[0030] 1 Bearing device 2 Outer ring (outer component) 2b Inner surface 2c One side in the axial direction 4 Inner ring member (inner member) 4b Outer surface 5 Inner ring (inner member) 10,10A,10B Sealing device 11, 11A First member 11a,11Aa One side in the axial direction 18, 18A, 18B Second member 24, 24A Elastic circular ring part (circular ring part) 24a,24Aa One side in the axial direction 25, 25A, 25B Recess 26, 26A Elastic cylindrical section (cylindrical section) 28 Circular part R labyrinth seal S2 External space

Claims

1. A sealing device comprising a first member attached to an outer member and a second member attached to an inner member that rotates coaxially with the outer member, the second member includes a cylindrical portion that constitutes a labyrinth seal communicating with an external space together with a radially opposing portion of the first member, and a ring portion that is provided so as not to protrude radially outward beyond an outer circumferential surface of the cylindrical portion and has a plurality of recesses that open onto the outer circumferential surface and are spaced apart in the circumferential direction; A sealing device characterized in that, when the sealing device is installed, the recess is provided so as to open on one axial side surface of the first member facing the external space and on one axial side of the one axial side surface of the outer member.

2. In claim 1, A sealing device characterized in that the recess is open on one axial side surface of the circular ring portion.

3. In claim 1 or 2, A sealing device characterized in that the circular ring portion is made of an elastic body.

4. In claim 3, The sealing device, wherein the elastic body constitutes a magnetic encoder.

5. In claim 4, A sealing device, characterized in that the recess has a depth dimension along the radial direction of the elastic body that is less than 1 / 2 of the diameter dimension of the elastic body.

6. A sealing structure in which a first member is attached to an outer member, and a second member is attached to an inner member that rotates coaxially with the outer member, A sealing structure characterized in that a labyrinth seal communicating with an external space is formed by a cylindrical portion of the second member and a portion of the first member radially opposed thereto, and a plurality of recesses are formed at intervals in the circumferential direction on the outer peripheral surface of the circular ring portion of the second member so as not to protrude outward beyond the outer peripheral surface of the cylindrical portion, and open on one axial side of the first member facing the external space and on one axial side of the one axial side of the outer member.

Images