JP2006046565A - Sealing device of rolling bearing, and hub unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device of a hub unit capable of improving its sealing performance, elongating the service life by stably supplying a lubricant, and improving the rigidity. <P>SOLUTION: The sealing devices 12a, 12b assembled in a rolling bearing wherein a plurality of rolling elements 10 are circumferentially rotatably mounted between an inner raceway ring 3 and an outer raceway ring 1, have sealing members 107, 217 for sealing an axial end part of a bearing space of the rolling bearing, and lubricant-containing plastic moldings 100A-100C, 100D-100G held on the sealing members 107, 217. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing sealing device and a hub unit, and more specifically, a rolling bearing sealing device for preventing dust, water, water vapor, muddy water, and the like from entering the inside of the bearing, and the sealing device. Relates to a hub unit in which is incorporated.

  For example, rolling bearings that support the wheels of automobiles and railway vehicles are usually used outdoors while being exposed to rainwater, wind and snow, and dust. In extreme cases, it may be used while immersed in water. Therefore, a sealing device is used in the conventional rolling bearing.

  FIG. 2 shows an example of a conventional hub unit that rotatably supports the wheels of an automobile. The hub unit O includes an outer ring equivalent member (outer raceway ring) 1 that is a fixed ring, an inner ring equivalent member (inner raceway ring) 3 that is a rotating wheel, and a plurality of rolling elements 10. The outer ring equivalent member 1 is supported and fixed to a suspension device (not shown) by a mounting portion 2 formed on the outer peripheral surface of the axial intermediate portion.

  The inner equivalent member 3 has a hub 4 and an inner ring 5. A mounting flange 7 is provided at an end portion on the outboard side of the outer peripheral surface of the hub 4 (an end portion on the outer side in the width direction when assembled to an automobile: the left end portion in FIG. 2), and the mounting flange 7 is a stud for mounting a wheel. A plurality of 7a are implanted at substantially equal intervals in the circumferential direction. A spline groove 6 is formed on the inner peripheral surface of the hub 4, and a drive shaft that is rotationally driven via a constant velocity joint is inserted into the spline groove 6 when assembled to the vehicle. The inner ring 5 is fitted into a small-diameter step portion at an inboard side end portion of the hub 4 (end portion on the inner side in the width direction when assembled to the automobile: right end portion in FIG. 2).

  Double-row outer ring raceway surfaces 8, 8 are formed on the inner peripheral surface of the outer ring equivalent member 1, and inner ring raceway surfaces 9, 9 are formed on the outer peripheral surface of the intermediate portion in the axial direction of the hub 4 and the outer ring surface of the inner ring 5, respectively. ing. A plurality of rolling elements 10 and 10 are arranged between the double row outer ring raceway surfaces 8 and 8 and the double row inner ring raceway surfaces 9 and 9, respectively, via a cage 11 so as to be able to roll in the circumferential direction. It is installed. In the illustrated example, balls are used as the rolling elements 10, 10, but in the case of a hub unit that is heavy, tapered rollers may be used as the rolling elements.

  Further, between the inboard side end of the outer ring equivalent member 1 and the inner ring 5, and between the outboard side end of the outer ring equivalent member 1 and the hub 4, sealing devices 12a and 12b are provided, and a hub unit is provided. Both end openings in the axial direction of the O bearing space 13 are sealed.

  The sealing device 12a includes a cored bar 105, a slinger 106, and a seal member 107 as shown in an enlarged view in FIG. Of these, the cored bar 105 is integrally formed by subjecting a metal plate such as a low carbon steel plate to punching processing such as press processing and plastic processing. The core metal 105 includes an outer diameter side cylindrical portion 109 that can be fitted and fixed to the inner peripheral surface of the end portion on the inboard side of the outer ring equivalent member 1, and an axial inner end green (see FIG. 3) of the outer diameter side cylindrical portion 109. The inner ring portion 110 is bent inward in the diameter direction from the left end edge) and is formed in a substantially L-shaped cross section.

  The slinger 106 is integrally formed by subjecting a metal plate having excellent corrosion resistance, such as a stainless steel plate, to a punching process such as a press process and a plastic process. The slinger 106 has an inner cylindrical portion 112 that can be fitted and fixed to the outer peripheral surface of the inner ring 5, and an outer side that is bent outward in the diametrical direction from the axial outer end edge (the right end edge in FIG. 3) of the inner cylindrical portion 112. It has an annular portion 113 and is formed in an L-shaped cross section.

  Further, the seal member 107 is formed of an elastic material such as rubber, and the base end portion thereof is bonded and fixed to the cored bar 105 by adhesion or the like, and the three seal lips 114, 115 on the outer side, the middle side, and the inner side are provided. 116 is provided.

  Then, the distal end edge of the outermost seal lip 114 located on the outermost side is brought into sliding contact with the inner side surface of the outer inner ring portion 113 of the slinger 106, and the distal ends of the intermediate seal lip 115 and the inner seal lip 116 which are the remaining two seal lips. By sliding the edge in contact with the outer peripheral surface of the inner diameter side cylindrical portion 112 of the slinger 106, leakage of the encapsulated grease is prevented, and entry of dust, water, muddy water, and the like from the outside into the bearing space 13 is prevented.

  On the other hand, the sealing device 12b includes a cored bar 216 and a sealing member 217, each of which is formed in an annular shape, as shown in an enlarged view in FIG. The cored bar 216 is integrally formed by subjecting a metal plate such as a low carbon steel plate to punching processing such as press processing and plastic processing. The core metal 216 includes an outer diameter side cylindrical portion 222 that can be fitted and fixed to the inner peripheral surface of the outer end of the outer ring equivalent member 1 and an outer end edge of the outer diameter side cylindrical portion 222 (the left end edge in FIG. 4). ) And a support plate portion 223 bent inward in the diameter direction.

  A large-diameter portion 224 is provided near the inner end of the outer-diameter side cylindrical portion 222 (near the right end in FIG. 4). The outer diameter of the large-diameter portion 224 in the free state is the outer-board-side end of the outer ring equivalent member 1. The large-diameter portion 224 can be fitted and fixed to the inner peripheral surface of the end portion on the outboard side of the outer ring equivalent member 1 by an interference fit.

  Further, the support plate portion 223 has a substantially S-shaped cross-sectional shape, and approaches the rolling element 10 installed in the bearing space 13 (rightward in FIG. 4) as it goes inward in the diameter direction (downward in FIG. 4). It is inclined to.

  On the other hand, the seal member 217 is formed of an elastic material such as rubber, and is insert-molded with respect to the core metal 216 or coupled and fixed to the core metal 216 by adhesion or the like. The seal member 217 covers the entire outer surface (left side surface in FIG. 4) of the support plate portion 223 of the core metal 216, and the outer peripheral end portion thereof is connected to the outer peripheral surface of the inclined portion 227 continuous from the outer diameter side cylindrical portion 222. The outer ring equivalent member 1 is sandwiched between the inner peripheral surface of the end portion on the outboard side.

  The outer diameter in the free state of the portion covering the outer peripheral surface of the inclined portion 227 at the outer peripheral end portion of the seal member 217 is set slightly larger than the inner diameter of the end portion on the outboard side of the outer ring equivalent member 1. In a state where the large-diameter portion 224 of the gold 216 is fitted and fixed to the inner peripheral surface of the end portion on the outboard side of the outer ring equivalent member 1, the outer peripheral end of the seal member 217 covers the outer peripheral surface of the inclined portion 227 of the core metal 216. The portion is elastically pressed between the outer peripheral surface of the inclined portion 227 and the inner peripheral surface of the end portion on the outboard side of the outer ring equivalent member 1 to ensure the sealing performance of the portion.

  In addition, the seal member 217 includes an outer diameter side, an inner diameter side, two side seal lips 218 and 219, and one radial seal lip 220. Then, the two side seal lips 218 and 219 are inclined outward in the diametrical direction (upward in FIG. 4) toward the front end edge (left end edge in FIG. 4), thereby allowing dust from the outside to enter the bearing space 13. Intrusion of foreign substances such as water and muddy water is prevented. The radial seal lip 220 is inclined toward the bearing space 13 (right side in FIG. 4) toward the tip edge (lower right edge in FIG. 4), thereby ensuring a grease leakage prevention function.

  FIG. 5 shows a sealing device in which the sealing lip shape of the sealing member is changed as a measure for improving the sealing performance. The sealing device 12c is configured to retract the inboard side end of the outer ring equivalent member 1 from the end surface of the inner ring 5, It arrange | positions at the retreat part (for example, refer patent document 2).

  The sealing device 12 c includes a slinger 316, a core metal 317, and a seal member 318, and the inner diameter side cylindrical portion 320 of the slinger 316 is externally fitted and fixed to the outer diameter surface of the inner ring 5, and the outer diameter side cylindrical portion of the core metal 317. 321 is fitted and fixed to the outer diameter surface of the outer ring equivalent member 1.

  The seal member 318 is integrally bonded and fixed to the cored bar 317 by adhesion or the like, and is disposed on the outer side and the inner side in the diametrical direction, and has two side seal lips 318a and 318b that are in sliding contact with the standing plate portion 319 of the slinger 316, A radial seal lip 318c that is in sliding contact with the inner diameter side cylindrical portion 320 of the slinger 316 is provided. In addition, the seal member 318 is provided with a cylindrical flange 318d on the inner peripheral surface in the vicinity of the tip, where the tip of the standing plate portion 319 of the slinger 316 faces with a slight radial gap.

The two side seal lips 318 a and 318 b provided on the seal member 318 are in sliding contact with the inner side surface of the standing plate portion 319 of the slinger 316, and the standing plate portion 319 of the slinger 316 is in contact with the flange portion 318 d of the seal member 318. By forming the labyrinth seal portion 310 in close proximity to each other, water resistance, mud water resistance and dust resistance are ensured, and the radial seal lip 318c is in sliding contact with the inner diameter side cylindrical portion 320 of the slinger 316, thereby causing grease leakage. The prevention function is said to be secured.
JP 2001-165179 A

  However, in the sealing devices 12a, 12b, and 12c shown in FIGS. 3 to 5, since the grease is sealed in the spaces between the seal lips of the seal member for lubrication, muddy water that enters the bearing space 13 from the outside or It is difficult to greatly reduce dust and the like. Such sealing devices 12a, 12b, and 12c exhibit sufficient sealing performance in a relatively clean environment with little water splashing and little dust, but as is well known, the hub unit is used outdoors. And sometimes exposed to rainwater, wind and snow, and dust, and in extreme cases, it may be used underwater (for example, in seawater or muddy water). May not be obtained.

  On the other hand, in order to improve the fuel efficiency of automobiles and the like, the hub unit is required to have a low torque, and in a sealing device, the seal member is often used with a low tension. For this reason, under the above-mentioned poor use environment, especially when immersed in muddy water, water pressure is also applied, so that the sealing performance of the sealing device cannot be maintained, and dust and the like enter the bearing and lubricate together with water. There is a risk of causing defects.

  The present invention has been made in order to eliminate such inconveniences, and the object thereof is to improve the sealing performance and to stably supply a lubricant to have a long life, Furthermore, it is providing the sealing device of a rolling bearing which can improve rigidity, and the hub unit incorporating this sealing device.

The object of the present invention is achieved by the following configurations.
(1) A sealing device incorporated in a rolling bearing in which a plurality of rolling elements are arranged so as to be able to roll in the circumferential direction between an inner race and an outer race,
A rolling bearing sealing device comprising: a sealing member that seals an axial end of a bearing space of the rolling bearing; and a lubricant-containing plastic molded body held by the sealing member.
(2) The rolling bearing sealing device according to (1), wherein a ratio of the polymer in the lubricant-containing plastic molded body is 20 to 90% by weight.
(3) A plurality of rolling elements are disposed between the inner raceway and the outer raceway so as to be able to roll in the circumferential direction, and either the inner raceway or the outer raceway is coupled and fixed to the wheel. A hub unit comprising the sealing device according to (1) or (2).

According to the present invention, since the lubricant-containing plastic molded body that is a solid material is held in a predetermined space of the seal member, the sealing performance is improved even when used in a harsh environment such as in muddy water. In addition, the rigidity can be increased, and the lubricant can be stably supplied from the lubricant-containing plastic molded article, so that the life can be extended.
In addition, by setting the polymer ratio in the lubricant-containing plastic molded body to 20 to 90% by weight, sufficient strength can be imparted to the lubricant-containing plastic molded body and the necessary lubricant content can be ensured. can do.

  Hereinafter, a rolling bearing sealing device and a hub unit according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of an essential part for explaining a hub unit sealing device according to an embodiment of the present invention. FIG. 1 (a) is a sealing device provided between an inboard side end of an outer ring and an inner ring. , (B) is a sealing device provided between the end portion of the outer ring on the outboard side and the hub. In this embodiment, the basic structure of the hub unit and the sealing device is taken as an example of the hub unit O and the sealing devices 12a and 12b already described with reference to FIGS. Therefore, the description is omitted or simplified.

  As shown in FIG. 1A, a sealing device 12a provided between an inboard side end of the outer ring equivalent member 1 and the inner ring 5 is a seal member 107 that seals one end of a bearing space 13 of the rolling bearing. And three annular lubricant-containing plastic molded bodies 100A, 100B, and 100C held by the seal member 107. The lubricant-containing plastic molded body 100A is held in a space A surrounded by the base end portion of the seal member 107, the outer seal lip 114, and the outer annular portion 113 of the slinger 106, and the lubricant-containing plastic molded body 100B is The lubricant-containing plastic molded body 100 </ b> C is held in a space B surrounded by the seal lip 114, the intermediate seal lip 115, and the outer ring portion 113 of the slinger 106, and the inner diameter of the inner seal lip 116, the intermediate seal lip 115, and the slinger 106 It is held in a space C surrounded by the side cylindrical portion 112.

  Further, as shown in FIG. 1B, the sealing device 12b provided between the end portion on the outboard side of the outer ring equivalent member 1 and the hub 4 seals the other end portion of the bearing space 13 of the rolling bearing. A seal member 217 is provided, and four annular lubricant-containing plastic molded bodies 100D, 100E, 100F, and 100G are held by the seal member 217. The lubricant-containing plastic molded body 100D is held in a space D surrounded by the outer side seal lip 218, the outer ring equivalent member 1 and the hub 4 of the seal member 217. The lubricant-containing plastic molded body 100E is retained by the outer side seal lip 218. Are held in a space E surrounded by the inner side seal lip 219 and the hub 4. The lubricant-containing plastic molded body 100F is held in a space F surrounded by the inner side seal lip 219, the radial seal lip 220, and the hub 4. The lubricant-containing plastic molded body 100G is axially inward of the radial seal lip 220. It is held in the space G on the outer diameter side of the hub 4 at the position (right side of FIG. 1B).

  Here, for convenience of explanation, the lubricant-containing plastic molded bodies 100A to 100G are held in all of the spaces A to G, but the sealing device 12a has at least any space among the spaces A to C. With regard to the sealing device 12b selected at one place, at least one arbitrary space among the spaces D to G can be selected, and the lubricant-containing plastic molded body can be held in each selected space. Further, depending on the location, in the space G, for example, the lubricant-containing plastic molded body 100G may be fixed using an annular garter spring.

  In a space where the lubricant-containing plastic molded body is not disposed, grease may be sealed as usual, or the lubricant-containing plastic molded body and grease may be used in combination. Moreover, it is preferable to apply grease or lubricating oil to the tip of each seal lip.

  Here, the lubricant-containing plastic molded article is a polymer selected from polyolefin-based polymers such as polyethylene, polypropylene, polybutylene, polymethylpentene, etc., as a lubricant, paraffin-based hydrocarbon oil such as poly-α-olefin oil, Mix and heat melt any of naphthenic hydrocarbon oil, mineral oil, ether oil such as dialkyldiphenyl ether, ester oil such as trimellitic acid ester, etc. For example, it is manufactured by compression molding or injection molding.

Although the average molecular weight of the polymer is in the range of 1 × 10 ^{3 to} 5 × 10 ⁶ , it is a relatively low molecular weight of 1 × 10 ³ to 1 × 10 ^{5 in} the lubricant-containing plastic molding. And those having an ultrahigh molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ are used alone or in combination according to the rigidity and moldability after molding.

  The lubricant-containing plastic molded body contains one or more of the following thermoplastic resins and thermosetting resins in addition to the polyolefin-based polymer for the purpose of improving mechanical strength. May be. Examples of the thermoplastic resin that can be contained include polyamide, polycarbonate, polybutylene terephthalate, polyphenylene sulfide, polyethersulfone, polyetheretherketone, polyamideimide, polystyrene, and ABS resin.

  Examples of thermosetting resins that can be contained include unsaturated polyester resins, urea resins, melamine resins, phenol resins, polyimide resins, and epoxy resins. In addition, in order to disperse these resins in a more uniform state with respect to the polyolefin-based polymer, molding may be performed by adding a compatibilizing agent as necessary. In addition to these, the lubricant-containing plastic molded article may contain various additives such as an antioxidant, a rust inhibitor, an antiwear agent, a defoaming agent, and an extreme pressure agent.

  The abundance ratio of the polymer to the lubricant is preferably polymer: lubricant = 20 to 90% by weight: 80 to 10% by weight. When the polymer content is less than 20% by weight, it is difficult to obtain strength as a molded body. Further, when the polymer content exceeds 90% by weight (the lubricant content is less than 10% by weight), the supply amount of the lubricant may be insufficient.

In addition, a conductive seal may be used to prevent radio noise in a car. In this case, in order to further increase the conductivity, the lubricant-containing plastic molded body may contain a conductive filler. The conductive fillers that can be contained in this lubricant-containing plastic molding include metals such as silver, copper, and aluminum, aluminum-doped zinc oxide, antimony-doped tin oxide-coated barium sulfate, antimony-doped tin oxide-coated aluminum borate, and antimony-doped. Non-metal oxides such as tin oxide coated titanium oxide, antimony doped tin oxide, nitrogen doped titanium oxide (titanium black), antimony doped tin oxide coated potassium titanate, carbon coated potassium titanate, oil furnace black, acetylene black, graphite, Examples thereof include carbon materials such as carbon fibers, conductive carbon black, and the like, and those having a high whisker-like or needle-like aspect ratio are preferable. The amount of the conductive filler added is suitably 10 to 40% by weight based on the total weight of the lubricant-containing plastic molded body.

  The hardness of the lubricant-containing plastic molded body is 85 or less, more preferably 80 or less on the spring hardness A scale described in JIS K 6301. In the tensile test, the breaking strength of the JIS No. 1 dumbbell test piece is preferably 9 MPa or less. If the spring hardness A scale exceeds 85 or the breaking strength exceeds 9 MPa, the lubricant-containing plastic molded article may not be able to follow the movement of the hub unit or the seal lip.

  As for the assembly method of the sealing device, the lubricant-containing plastic molded body is formed into a cylindrical shape having a cross-sectional shape substantially the same as the cross-sectional shape of the selected space, and is then inserted and held in the selected space. In this case, the lubricant-containing plastic molded body is not limited to the cylindrical shape, and may be held in the selected space by using one that is divided into two or more in the circumferential direction. In this way, it is possible to facilitate the work of assembling the lubricant-containing plastic molded body into the selected space of the seal member.

  Further, the lubricant-containing plastic molded body does not cause a problem even if it comes into contact with the slinger 106 or the hub 4 because the lubricant comes out from itself. Rather, when the lubricant-containing plastic molded body is in contact with the slinger 106 or the hub 4, water or foreign matter from the outside does not enter the bearing space 13 any more, and the sealing performance is improved. Further, in the vicinity of the seal lip portion of the seal member, for example, referring to FIG. 1A, the lip tip of the outer seal lip 114 and the outer annular portion 113 of the slinger 106 slide to move the lip 114. Therefore, it is preferable to provide a gap between the lip 114 and the lubricant-containing plastic molded body 100B.

  Thus, according to the rolling bearing sealing device and the hub unit of the present embodiment, the lubricant-containing plastic molded bodies 100A to 100G, which are solid substances, are held in the arbitrary selected spaces A to G of the seal members 107 and 217. As a result, even when used in harsh environments such as in muddy water, the sealing performance can be improved and the rigidity can be increased. Since it is supplied stably, it can have a long life.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is further demonstrated, this invention is not restrict | limited at all by this.

  In FIG. 1, spaces B and C of the sealing device 12a and spaces E and F of the sealing device 12b in which the lubricant-containing plastic molding is held are used as examples, and the spaces B and C of the sealing device 12a and the sealing device 12b As a comparative example in which grease of 30% of the space volume was sealed in the spaces E and F, a comparative test of sealing performance was performed in a state of being incorporated in the hub unit. In addition, the lubricant containing plastic molding used for the present Example is produced on condition of the following.

[Materials used]
(Polyolefin polymer)
Made by Mitsui Petrochemical Co., Ltd., ultra high molecular weight polyethylene, Mipperon (registered trademark) XM220: 9% by weight
Low molecular weight polyethylene PZ50U manufactured by Mitsubishi Oil Chemical Co., Ltd. 21% by weight
(lubricant)
Made by Nippon Oil Co., Ltd., paraffinic mineral oil FBK oil “RO100”: 50% by weight
[Molding condition]
Molding method: injection molding (in-line screw type)
Mold temperature: 70 ° C
Resin temperature: 170 ° C
Molding pressure: 400 kg / cm ² (39.2 MPa)

  About the Example and comparative example of this invention, the test of sealing performance was implemented supposing the case where it was immersed in muddy water using the rotation testing machine by NSK Ltd.

In the test, the sealability was evaluated after rotating continuously for 100 hours under the following test conditions.
Rotational speed: 1000min ^-1
Rotation time: 100 hours Shaft eccentricity: 0.5mm TIR
Mud composition: JIS 8 class dust 20% (immersion to shaft center)
Grease: Urea soap, mineral oil

  As a result, in the example using the lubricant-containing plastic, the moisture content contained in the grease applied to the hub unit was 1% or less, and good sealing performance was obtained. On the other hand, in the comparative example in which the grease was enclosed, the amount of water contained in the grease exceeded 5%, and sufficient sealing performance was not obtained.

  As mentioned above, the Example of this invention showed the sealing performance better than the comparative example. That is, it has been confirmed that the lubricant-containing plastic molded body is held in the selected space of the sealing member of the sealing device to have excellent sealing performance.

In addition, this invention is not limited to the said embodiment and Example, In the range which does not deviate from the summary of this invention, a change, a modification, improvement, etc. are possible suitably.
Although the hub unit has been described in the present embodiment, the rolling bearing sealing device of the present invention can also be applied to a bearing device that supports wheels of a railway vehicle. Moreover, the structure of a rolling bearing and the structure of a sealing device are not limited to this embodiment.

  Further, in this embodiment, the cross-sectional shape of the lubricant-containing plastic molded body is substantially the same as the cross-sectional shape of the seal member selection space, but this is not necessarily required and can be held in the seal member selection space. In addition, a lubricant-containing plastic molded article having an arbitrary cross-sectional shape may be used as long as the effects of the present invention can be obtained.

It is principal part sectional drawing of the sealing device of the hub unit which is one Embodiment of this invention, (a) is the sealing device provided between the inboard side edge part of an outer ring | wheel, and an inner ring | wheel, (b) is an outer ring | wheel. This is a sealing device provided between the outboard side end and the hub. It is sectional drawing which shows an example of the conventional hub unit. It is principal part sectional drawing which shows the conventional sealing device provided between the inboard side edge part and outer ring | wheel of an outer ring | wheel. It is principal part sectional drawing which shows the conventional sealing device provided between the outboard side edge part of the outer ring | wheel, and the hub. It is principal part sectional drawing which shows the other conventional sealing device.

Explanation of symbols

O Hub unit 1 Outer ring equivalent member (outer raceway ring)
3 Inner ring equivalent member (inner race)
4 Hub 5 Inner ring 10 Rolling elements 12a and 12b Sealing devices 100A to 100G Lubricant-containing plastic molded bodies 107 and 217 Seal members

Claims (3)

A sealing device incorporated in a rolling bearing in which a plurality of rolling elements are arranged so as to be able to roll in a circumferential direction between an inner race and an outer race,
A rolling bearing sealing device comprising: a sealing member that seals an axial end of a bearing space of the rolling bearing; and a lubricant-containing plastic molded body held by the sealing member.   The rolling bearing sealing device according to claim 1, wherein a ratio of the polymer in the lubricant-containing plastic molded body is 20 to 90% by weight.   A plurality of rolling elements are disposed between the inner raceway and the outer raceway so as to roll in the circumferential direction, and either the inner raceway or the outer raceway is a hub for coupling and fixing the wheels. A hub unit, wherein the sealing device according to claim 1 or 2 is incorporated.

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