Constant velocity joint for a vehicle

Abstract

The present invention relates to a constant velocity joint for a vehicle, the constant velocity joint including: a axle housing fixed to a knuckle by a hub bearing; a joint assembly inserted into an inner diameter portion of the axle housing and configured to transmit power from a shaft to the axle housing through a plurality of joint balls; an expansion portion formed by radially expanding an end portion of a body inside of the axle housing such that the expansion portion provides an axial pressing force to an inner ring of the hub bearing; and a dust shield having one side surrounding an outside of the expansion portion and coupled to the expansion portion to form an axial restraint force between the expansion portion and the dust shield.

Description

Technical Field

[0001] This disclosure relates to the structure of a constant velocity joint that transmits power to the drive wheels of a vehicle. Background Technology

[0002] The statements in this section provide only background information in connection with this disclosure and do not constitute prior art.

[0003] A constant velocity joint is a component that absorbs displacement between the differential and the drive wheels and transmits power to the drive wheels at a constant angular velocity. It is configured such that the bendable parts are surrounded by a dust cover to prevent foreign objects from penetrating from the outside.

[0004] Typically, one side of the constant velocity joint is connected to the differential, while the other side is connected to the drive wheel via the wheel hub. However, in some cases, the wheel hub and the constant velocity joint are integrally formed.

[0005] The content described as prior art is provided only to help understand the context of this disclosure and should not be construed as corresponding to prior art known to a person skilled in the art. Summary of the Invention

[0006] This disclosure provides a constant velocity joint for vehicles. When the constant velocity joint has a hub integrally formed therewith, a secure connection of the dust cover can be easily ensured, and the sealing function of the connected dust cover can be well ensured, thereby ultimately ensuring the durability of the bending portion of the constant velocity joint, and ensuring the excellent assemblability and maintainability of the constant velocity joint.

[0007] According to one embodiment of this disclosure, a constant velocity joint for a vehicle includes: an axle housing fixed to a steering knuckle via a hub bearing; a joint assembly inserted into the inner diameter portion of the axle housing and configured to transmit power from the axle to the axle housing via a plurality of joint balls; an expansion portion formed by radially expanding and deforming the inner end of the axle housing at its inner side, and configured such that the expansion portion provides axial pressing force to the inner ring of the hub bearing; and a dust cover, one side of which surrounds the outer side of the expansion portion and is coupled to the expansion portion to form an axial restraint force between the expansion portion and the dust cover.

[0008] The expansion portion may have a protrusion whose outer diameter is larger than the outer diameter of the inner ring's inner body end.

[0009] The dust cover may have a first contact portion, a second contact portion, and a third contact portion forming an inner groove: the first contact portion contacts the end of the expansion portion inside the vehicle body; the second contact portion is connected to the first contact portion and contacts the outermost side of the protrusion; the third contact portion is connected to the second contact portion and contacts the protrusion on the outside of the vehicle body, the protrusion being inserted into the inner groove.

[0010] Meanwhile, the protrusion may have a first inclined portion formed on the outer side of the vehicle body, the outer diameter of the first inclined portion gradually decreasing towards the outer side of the vehicle body, and the third contact portion of the dust cover is formed parallel to the first inclined portion.

[0011] The dust cover may have an integrally formed first protruding end that partially protrudes from the end of the first contact portion toward the inner side of the vehicle body of the expansion portion.

[0012] The inner ring may have a second inclined portion, which is formed to have an outer diameter that gradually increases from the end of the second inclined portion that connects with the expansion portion toward the outer side of the vehicle body; the dust cover may have a fourth contact portion, which is connected to the third contact portion and is formed parallel to the second inclined portion to contact the second inclined portion.

[0013] The dust cover may have an integrally formed second protruding end that partially protrudes from the fourth contact portion toward the second inclined portion of the inner ring.

[0014] The inner ring may have a first circumferential portion, formed with a constant outer diameter extending from the end of the first circumferential portion that connects to the expansion portion toward the outer side of the vehicle body; a second circumferential portion, connected to the first circumferential portion, and the constant outer diameter formed by the second circumferential portion is greater than the constant outer diameter of the first circumferential portion; and a dust cover may extend from a third contact portion to surround both the first circumferential portion and the second circumferential portion.

[0015] The inner surface of the second circumference of the dust cover can form a third inclined portion, the inner diameter of which gradually decreases toward the outer side of the vehicle body.

[0016] The expansion portion can be formed by rolling to deform the inner end of the axle housing in the radial direction outward, so that the expansion portion presses the inner end of the inner ring in the axial direction to fix the inner ring, and the expansion portion has a protrusion whose outer diameter is larger than the outer diameter of the inner end of the inner ring.

[0017] The strap can be fastened to the outside of the dust cover to press the dust cover toward the inside of the vehicle body and the protrusion.

[0018] The outer side of the dust cover may have a fastening groove to fasten the strap to the dust cover; when the axial thickness of the expansion is denoted as t, and the distance from the end of the expansion inside the vehicle body to the end of the fastening groove inside the vehicle body is denoted as L, the position of the end of the fastening groove inside the vehicle body may be in the range of 0≤L / t≤0.5.

[0019] When the outer diameter of the protrusion is denoted as d, and the outer diameter of the inner ring's inner end is denoted as D1, the outer diameter d of the protrusion can be within the range of 1.02≤d / D1≤1.05 to securely assemble the dust cover and suppress or prevent the dust cover from detaching.

[0020] When the axial width of the belt is denoted as B and the axial thickness of the expansion portion is denoted as t, the axial width B of the belt is within the range of 0.3 ≤ t / B ≤ 1 to ensure sufficient sealing.

[0021] According to another embodiment of this disclosure, the dust cover for a constant velocity joint in a vehicle is configured to allow an expansion portion of the axle housing to be inserted into the dust cover to create an axial constraint between the expansion portion and the dust cover. Specifically, the axle housing receives power from the axle via a plurality of joint balls and is fixed to the steering knuckle via a hub bearing. The expansion portion is formed by deforming a portion of the axle housing, and the expansion portion expands radially within the axle housing and presses against the inner ring of the hub bearing axially to secure the inner ring.

[0022] The dust cover may include: a first contact portion that contacts the end of the inner side of the expansion portion inside the vehicle body; a second contact portion that is connected to the first contact portion and contacts the outermost side of the protrusion, such that the outer diameter of the protrusion is larger than the outer diameter of the end of the inner side of the inner ring inside the vehicle body; and a third contact portion that is connected to the second contact portion and contacts the protrusion on the outer side of the vehicle body.

[0023] The protrusion may have a first inclined portion formed on the outer side of the vehicle body, the outer diameter of the first inclined portion gradually decreasing towards the outer side of the vehicle body, and the third contact portion of the dust cover is formed parallel to the first inclined portion.

[0024] The dust cover may have an integrally formed first protruding end that partially protrudes from the end of the first contact portion toward the inner side of the vehicle body of the expansion portion.

[0025] The inner ring has a second inclined portion, which is formed to have an outer diameter that gradually increases from the end where the second inclined portion connects with the expansion portion toward the outer side of the vehicle body. The dust cover may have a fourth contact portion, which is connected to the third contact portion and is formed parallel to the second inclined portion to contact the second inclined portion.

[0026] The dust cover may have an integrally formed second protruding end that partially protrudes from the fourth contact portion toward the second inclined portion of the inner ring.

[0027] When the inner ring may include: a first circumferential portion having a constant outer diameter extending outward from the end of the first circumferential portion that connects to the expansion portion toward the outside of the vehicle body; and a second circumferential portion connected to the first circumferential portion, and the constant outer diameter of the second circumferential portion being greater than the constant outer diameter of the first circumferential portion, the dust cover may extend from the third contact portion to surround both the first circumferential portion and the second circumferential portion.

[0028] The inner surface of the second circumference of the dust cover can form a third inclined portion, the inner diameter of which gradually decreases toward the outer side of the vehicle body.

[0029] The outer side of the dust cover may have a fastening groove to fasten the strap to the dust cover; when the axial thickness of the expansion is denoted as t, and the distance from the end of the expansion inside the vehicle body to the end of the fastening groove inside the vehicle body is denoted as L, the position of the end of the fastening groove inside the vehicle body may be in the range of 0≤L / t≤0.5.

[0030] When the axial width of the belt is denoted as B and the axial thickness of the expansion portion is denoted as t, the axial width B of the belt can be in the range of 0.3≤t / B≤1; and the belt fastening groove is formed to have a width that accommodates the belt and constrains the axial ends of the belt.

[0031] Further applicability will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0032] To facilitate understanding of this disclosure, various embodiments of the disclosure, given by way of example, will now be described with reference to the accompanying drawings, in which:

[0033] Figure 1 This is a diagram illustrating a constant velocity joint for a vehicle according to a first embodiment of the present disclosure;

[0034] Figure 2 yes Figure 1 Detailed diagram of the main parts;

[0035] Figure 3 This is a diagram illustrating a constant velocity joint for a vehicle according to a second embodiment of the present disclosure;

[0036] Figure 4 This is a diagram illustrating a constant velocity joint for a vehicle according to a third embodiment of the present disclosure; and

[0037] Figure 5 This is a diagram illustrating a constant velocity joint for a vehicle according to a fourth embodiment of the present disclosure.

[0038] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0039] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or its uses. It should be understood that corresponding reference numerals denote the same or corresponding parts and features throughout the drawings.

[0040] Reference Figures 1 to 5 The constant velocity joints for vehicles according to some embodiments of this disclosure commonly include: an axle housing 7 having a plurality of hub bolts 1 and being fixed to a steering knuckle 5 by a hub bearing 3; a joint assembly 13 inserted into the inner diameter portion of the axle housing 7 and configured to transmit power from axle 9 to the axle housing 7 via a plurality of joint balls 11; an expansion portion 15 formed by radially expanding and deforming the inner end of the axle housing 7 on the inner side of the vehicle body, such that the expansion portion 15 provides axial pressing force to the inner ring 3-1 of the hub bearing 3; and a dust cover 17, one side of which surrounds the outer side of the expansion portion 15 and is coupled to the expansion portion 15 to form an axial restraint force between the expansion portion 15 and the dust cover 17.

[0041] In other words, the constant velocity joint according to this disclosure is configured to transmit the power from the axle 9 to the axle housing 7 via the joint assembly 13, thus forming a constant velocity joint integral with the wheel hub. Here, the axle housing 7 is configured to connect to the dust cover 17 by forming an expansion portion 15 that secures the inner ring 3-1 of the wheel hub bearing 3 through radial expansion deformation of a portion of the axle housing 7.

[0042] The expansion portion 15 has a protrusion 15-1, the outer diameter of which is larger than the outer diameter of the end of the inner ring 3-1 inside the vehicle body.

[0043] In other words, the protrusion 15-1 is part of the expansion portion 15, which refers to the outward protrusion of the expansion portion 15 formed by radially expanding outward at the end of the axle housing 7 inside the vehicle body, other than the portion that presses against the inner ring 3-1 in the axial direction.

[0044] In essence, the expansion portion 15 expands and deforms the inner end of the axle housing 7 radially outward by the orbital forming method. Thus, the expansion portion 15 not only presses the inner end of the inner ring 3-1 axially to fix the inner ring 3-1, but also has a protrusion 15-1, the outer diameter of which is larger than the outer diameter of the inner end of the inner ring 3-1.

[0045] As described above, the dust cover 17 is fastened to the protrusion 15-1 to form an axial restraint between the expansion 15 and the dust cover 17.

[0046] Here, axial direction refers to the direction of rotation of the axle housing 7, and radial direction refers to the radial direction centered on the axial direction.

[0047] For reference, in the case of the front wheels, the axle housing 7 is fixed to the steering knuckle 5, while in the case of the rear wheels, the axle housing 7 can be fixed to the wheel carrier.

[0048] In addition, as described above, one side of the dust cover 17 is connected to the expansion portion 15 of the axle housing 7, and the other side of the dust cover 17 is connected to the axle 9 to allow bending between the axle 9 and the axle housing 7, while sealing and blocking the bending portion from the outside to suppress or prevent the penetration of foreign matter.

[0049] The dust cover 17 has a first contact portion 19, a second contact portion 21, and a third contact portion 23 forming an inner groove 25, wherein the first contact portion 19 contacts the end of the expansion portion 15 inside the vehicle body; the second contact portion 21 is connected to the first contact portion 19 and contacts the outermost side of the protrusion 15-1; the third contact portion 23 is connected to the second contact portion 21 and contacts the protrusion 15-1 on the outside of the vehicle body, the protrusion 15-1 being inserted into the inner groove 25.

[0050] In other words, by inserting the protrusion 15-1 of the expansion portion 15 into the inner groove 25 formed by the first contact portion 19, the second contact portion 21 and the third contact portion 23 of the dust cover 17, an axial constraint force is formed between the dust cover 17 and the axle housing 7.

[0051] Of course, the band 27 is attached to the outside of the dust cover 17. The band 27 is attached to press the dust cover 17 from the outside toward the end of the inner ring 3-1 and the protrusion 15-1 inside the vehicle body, thereby keeping the dust cover 17 in a stable attached state.

[0052] The outer side of the dust cover 17 has a fastening groove 29 to fasten the strap 27 to the dust cover 17. When the axial thickness of the expansion 15 is denoted as t, and the distance from the end of the expansion 15 inside the vehicle body to the end of the vehicle body with the fastening groove 29 inside the vehicle body is denoted as L, the position of the end of the vehicle body with the fastening groove 29 inside the vehicle body is in the range of 0 ≤ L / t ≤ 0.5.

[0053] In other words, when the position of the end of the inner side of the vehicle body with the fastening groove 29 is set as described above, the position of the end of the inner side of the vehicle body with the belt 27 is located at the position that firmly surrounds the outside of the expansion 15 to press the expansion 15, which is beneficial for placing the dust cover 17 and ensuring the sealing of the dust cover 17.

[0054] Meanwhile, when the outer diameter of protrusion 15-1 is denoted as d, and the outer diameter of the inner end of the inner ring 3-1 on the inner side of the vehicle body is denoted as D1, the outer diameter d of protrusion 15-1 is in the range of 1.02≤d / D1≤1.05.

[0055] This effectively limits the protrusion height of the protrusion 15-1 of the expansion portion 15, ensuring that the protrusion height of the protrusion 15-1 is not too high, thereby securely assembling the dust cover 17, and ensuring that the protrusion height of the protrusion 15-1 is not too low, thereby effectively suppressing or preventing the dust cover 17 from detaching.

[0056] Meanwhile, when the axial width of the band 27 is denoted as B and the axial thickness of the expansion portion 15 is denoted as t, the axial width B of the band 27 is within the range of 0.3 ≤ t / B ≤ 1.

[0057] This makes the axial width of the strip 27 greater than or equal to the axial thickness of the expansion portion 15, and the axial width of the strip 27 is not too wide, about 3 times or more the axial thickness of the expansion portion 15, thereby not only ensuring sufficient sealing of the dust cover 17, but also making it easy to handle and assemble the strip 27.

[0058] Of course, the fastening groove 29 can be formed to have a width that accommodates the belt 27 and constrains both ends of the belt 27.

[0059] Meanwhile, the protrusion 15-1 has a first inclined portion 31 formed on the outer side of the vehicle body of the protrusion 15-1, the outer diameter of the first inclined portion 31 gradually decreases towards the outer side of the vehicle body, and the third contact portion 23 of the dust cover 17 is formed parallel to the first inclined portion 31.

[0060] The first inclined portion 31 allows the third contact portion 23 of the dust cover 17 to be placed thereon, so that the dust cover 17 can be easily assembled, and a tight connection is naturally created between the dust cover 17 and the protrusion 15-1 by the pressing force of the band 27, thereby ensuring a higher seal.

[0061] The common configurations in all embodiments of this disclosure have been described above. The remaining embodiments of this disclosure will be described below.

[0062] Reference Figure 3 The second embodiment of this disclosure is similar to Figure 1 The first embodiment shown is almost identical, except that the dust cover 17 has an integrally formed first protruding end 33 that partially protrudes from the end of the first contact portion 19 toward the inner side of the vehicle body of the expansion portion 15.

[0063] The first protruding end 33 is deformed into a compressed state between the dust cover 17 and the end of the expansion portion 15, thereby forming a more reliable seal.

[0064] like Figure 4 The third embodiment of this disclosure shown is similar to Figure 3 The second embodiment shown is almost identical, except that the inner ring 3-1 has a second inclined portion 35, which is formed to have an outer diameter that gradually increases from the end that connects with the expansion portion 15 toward the outside of the vehicle body; the dust cover 17 has a fourth contact portion 37, which is connected to the third contact portion 23 and is formed parallel to the second inclined portion 35 to contact the second inclined portion 35.

[0065] In addition, the dust cover 17 has an integrally formed second protruding end 39, which protrudes partially from the fourth contact portion 37 toward the second inclined portion 35 of the inner ring 3-1.

[0066] Therefore, the dust cover 17, which is pressed by the strap 27 toward the expansion portion 15 of the axle housing 7, can more reliably and firmly seal the bend between the axle housing 7 and the shaft 9 according to the first sealing portion S1, the second sealing portion S2, the third sealing portion S3 and the fourth sealing portion S4. The first sealing portion S1 is formed by the first contact portion 19 and the inner end of the expansion portion 15. The second sealing portion S2 is formed by the second contact portion 21 and the outermost part of the protrusion 15-1. The third sealing portion S3 is formed by the third contact portion 23 and the first inclined portion 31. The fourth sealing portion S4 is formed by the fourth contact portion 37 and the second inclined portion 35.

[0067] like Figure 5 The fourth embodiment of this disclosure shown is similar to Figure 3 The second embodiment shown is almost identical, except that the inner ring 3-1 has a first circumferential portion 41 and a second circumferential portion 43. The first circumferential portion 41 is formed with a constant outer diameter extending from its end that connects to the expansion portion 15 toward the outer side of the vehicle body. The second circumferential portion 43 is connected to the first circumferential portion 41, and the constant outer diameter of the second circumferential portion 43 is larger than the constant outer diameter of the first circumferential portion 41. The dust cover 17 extends from the third contact portion 23 to surround both the first circumferential portion 41 and the second circumferential portion 43.

[0068] In addition, the dust cover 17 has a structure that surrounds the inner surface of the second circumferential portion 43 to form a third inclined portion 45, the inner diameter of which gradually decreases toward the outer side of the vehicle body.

[0069] In this configuration, the side of the dust cover 17 facing the inner ring 3-1 is positioned on the first circumferential portion 41 and the second circumferential portion 43 to prevent the penetration of foreign objects. Specifically, the third inclined portion 45 of the dust cover 17, which contacts the second circumferential portion 43, is structurally designed to secure the outer end of the dust cover 17 to the second circumferential portion 43 using a strong fastening force, thereby further reliably preventing the penetration of foreign objects.

[0070] According to this disclosure, in a constant velocity joint with an integrally formed hub, a stable connection of the dust cover can be easily ensured, and the sealing function of the connected dust cover can be well ensured, thereby ultimately ensuring the durability of the bending portion of the constant velocity joint, and ensuring the excellent assemblability and maintainability of the constant velocity joint.

[0071] Although this disclosure has been shown and described with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made to this disclosure without departing from the spirit and scope of the invention.

Claims

1. An equal-velocity joint for a vehicle, comprising: a knuckle housing fixed to a knuckle by a hub bearing; a joint assembly inserted into an inner diameter portion of the knuckle housing and transmitting power from a shaft to the knuckle housing by a plurality of joint balls; an expansion portion formed by radially expanding an end portion of a body inner side of the knuckle housing such that the expansion portion provides an axial pressing force to an inner ring of the hub bearing; and a dust cover having one side configured to: surround an outer side of the expansion portion, be coupled to the expansion portion, and form an axial restraint force between the expansion portion and the dust cover, wherein the expansion portion has a protrusion having an outer diameter greater than an outer diameter of the end portion of the body inner side of the inner ring, the dust cover includes a first contact portion forming an inner groove, a second contact portion, and a third contact portion, the first contact portion being in contact with the end portion of the body inner side of the expansion portion; the second contact portion being connected to the first contact portion and being in contact with an outermost side of the protrusion; and the third contact portion being connected to the second contact portion and being in contact with the protrusion at a body outer side, the protrusion being inserted into the inner groove, and the protrusion has a first inclined portion formed on the body outer side of the protrusion, the first inclined portion having an outer diameter gradually decreasing toward the body outer side, and the third contact portion of the dust cover being formed in parallel with the first inclined portion. 2.The equal-velocity joint of claim 1, wherein the dust cover has a first protruding end partially protruding from the first contact portion toward the end portion of the body inner side of the expansion portion. 3.The equal-velocity joint of claim 1, wherein the inner ring has a second inclined portion having an outer diameter gradually increasing toward the body outer side from an end portion of the second inclined portion meeting the expansion portion; and the dust cover has a fourth contact portion connected to the third contact portion and shaped in parallel with the second inclined portion to be in contact with the second inclined portion. 4.The equal-velocity joint of claim 3, wherein the dust cover has a second protruding end partially protruding from the fourth contact portion toward the second inclined portion of the inner ring. 5.The equal-velocity joint of claim 1, wherein the inner ring includes: a first circumferential portion having a constant outer diameter toward the body outer side from an end portion of the first circumferential portion meeting the expansion portion; and a second circumferential portion connected to the first circumferential portion and having a constant outer diameter greater than the constant outer diameter of the first circumferential portion; and the dust cover extends from the third contact portion to surround both the first circumferential portion and the second circumferential portion. 6.The equal-velocity joint of claim 5, wherein an inner side surface of the dust cover surrounding the second circumferential portion forms a third inclined portion having an inner diameter gradually decreasing toward the body outer side. 7.The equal-velocity joint of claim 1, wherein The end of the vehicle body inner side of the axle housing is expanded and deformed outward in the radial direction, and The expansion portion presses the end of the vehicle body inner side of the inner ring in the axial direction to fix the inner ring, and the expansion portion has a protrusion having an outer diameter greater than that of the end of the vehicle body inner side of the inner ring.

8. The constant velocity joint according to claim 7, wherein The band is fastened to the outer side of the dust cover, and the dust cover is pressed toward the end of the vehicle body inner side of the inner ring and the protrusion.

9. The constant velocity joint according to claim 8, wherein The dust cover has a band fastening groove formed on the outer side of the dust cover, and the band is fastened to the dust cover, and When an axial thickness of the expansion portion is represented as t, and a distance from the end of the vehicle body inner side of the expansion portion to the end of the vehicle body inner side of the band fastening groove is represented as L, a position of the end of the vehicle body inner side of the band fastening groove is within a range of 0≤L / t≤0.

5.

10. The constant velocity joint according to claim 8, wherein When an outer diameter of the protrusion is represented as d, and an outer diameter of the end of the vehicle body inner side of the inner ring is represented as Dl, the outer diameter d of the protrusion is within a range of 1.02≤d / Dl≤1.05 to firmly assemble the dust cover, and to inhibit or prevent the dust cover from coming off.

11. The constant velocity joint according to claim 8, wherein When an axial width of the band is represented as B and an axial thickness of the expansion portion is represented as t, the axial width B of the band is within a range of 0.3≤t / B≤1 to ensure sufficient sealability.

12. A dust cover for a constant velocity joint of a vehicle, The dust cover allows an expansion portion of an axle housing to be inserted into the dust cover to form an axial restraining force between the expansion portion and the dust cover, wherein The axle housing receives power from a shaft through a plurality of joint balls, and is fixed to a knuckle through a hub bearing, the expansion portion is formed by deforming a portion of the axle housing, and the expansion portion expands in a radial direction of the axle housing, and presses an inner ring of the hub bearing in an axial direction to fix the inner ring, The dust cover includes a first contact portion in contact with an end of a vehicle body inner side of the expansion portion, a second contact portion connected to the first contact portion, and in contact with an outermost side of a protrusion of the expansion portion having an outer diameter greater than that of the end of the vehicle body inner side of the inner The protrusion has a first inclined portion formed on the vehicle body outer side of the protrusion, an outer diameter of the first inclined portion gradually decreases toward the vehicle body outer side, and the third contact portion of the dust cover is formed in parallel with the first inclined portion.

13. The dust cover according to claim 12, wherein The dust cover has a first protruding end partially protruding from the first contact portion toward the end of the vehicle body inner side of the expansion portion.

14. The dust cover according to claim 12, wherein the inner ring has a second inclined portion having an outer diameter that gradually increases toward the vehicle body outside from an end portion of the second inclined portion that is continuous with the expanded portion; and the dust cover has a fourth contact portion connected to the third contact portion and shaped in parallel with the second inclined portion to be in contact with the second inclined portion.

15. The dust cover according to claim 14, wherein the dust cover has a second protruding end that partially protrudes from the fourth contact portion toward the second inclined portion of the inner ring.

16. The dust cover according to claim 12, wherein the inner ring includes: a first circumferential portion having a constant outer diameter that gradually increases toward the vehicle body outside from an end portion of the first circumferential portion that is continuous with the expanded portion; and a second circumferential portion connected to the first circumferential portion, and having a constant outer diameter that is larger than the constant outer diameter of the first circumferential portion; the dust cover extends from the third contact portion to surround both the first circumferential portion and the second circumferential portion.

17. The dust cover according to claim 16, wherein an inner side surface of the dust cover that surrounds the second circumferential portion forms a third inclined portion having an inner diameter that gradually decreases toward the vehicle body outside.

18. The dust cover according to claim 12, wherein an outer side of the dust cover has a belt fastening groove to fasten a belt to the dust cover, and when an axial thickness of the expanded portion is denoted as t, and a distance from an end portion of the expanded portion on the vehicle body inside to an end portion of the belt fastening groove on the vehicle body inside is denoted as L, a position of the end portion of the belt fastening groove on the vehicle body inside is within a range of 0 < L / t < 0.

5.

19. The dust cover according to claim 18, wherein when an axial width of the belt is denoted as B and an axial thickness of the expanded portion is denoted as t, the axial width B of the belt is within a range of 0.3 < t / B < 1; and the belt fastening groove is formed to have a width that accommodates the belt and restricts the axial both ends of the belt.

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