Wheel bearing device

Abstract

Provided is a wheel bearing device capable of preventing or reducing sticking between a wheel pilot part and a wheel. In this wheel bearing device 1, a hub wheel 3 includes: a wheel pilot part 3g which is positioned on an outer side of a hub flange 3b and to which a wheel can be fitted; and a brake rotor fitting part 3j which is positioned between the wheel pilot part 3g and the hub flange 3b and to which a brake rotor BR can be fitted. The wheel pilot part 3g includes a large-diameter part 31 which is fitted to a wheel WH of a vehicle in the wheel pilot part 3g and has a maximum outer diameter a, and a small-diameter part 32 which is positioned closer to an inner side than the large diameter part 31 and has a minimum outer diameter b in the wheel pilot part 3g.

Description

Wheel bearing device

[0001] The present invention relates to a wheel bearing device.

[0002] Conventionally, a wheel bearing device for rotatably supporting a wheel in a suspension device of an automobile or the like is known. Some wheel bearing devices have a wheel pilot portion on the outer side end of the hub ring, into which the inner peripheral surface of the wheel is fitted.

[0003] In such a wheel bearing device, the wheel pilot portion of the hub ring and the wheel may be fixed due to dirt, rust, etc. generated by the use environment or over time. When fixing occurs, it has been difficult to remove the wheel from the hub ring.

[0004] Therefore, in the wheel bearing device disclosed in Patent Document 1, a recess with a depth of 1 to 3 mm is formed on the outer peripheral surface of the wheel pilot portion. When fixing occurs between the wheel pilot portion and the wheel, a tool is penetrated into the recess to make it easier to remove the wheel from the wheel pilot portion.

[0005] JP-A-2023-114190

[0006] However, when a tool is penetrated into the recess of the wheel pilot portion, the hub ring may be damaged, which may lead to damage to the wheel bearing device.

[0007] The present invention has been made in view of the above situation, and provides a wheel bearing device that can prevent or reduce the fixing between the wheel pilot portion and the wheel, and can easily remove the wheel from the wheel pilot portion without using a tool.

[0008] That is, the wheel bearing device comprises an outer member having double rows of outer raceway surfaces on its inner circumference, a hub ring having a hub flange at its outer end for supporting a wheel, and at least one inner ring press-fitted to the inner side of the hub ring beyond the hub flange, an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, and double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member, wherein the hub ring has a wheel pilot portion located on the outer side of the hub flange and into which a wheel can be fitted, and a brake rotor fitting portion located between the wheel pilot portion and the hub flange and into which a brake rotor can be fitted, and the wheel pilot portion has a large diameter portion having a maximum outer diameter a that fits with the wheel in the wheel pilot portion, and a small diameter portion located on the inner side of the large diameter portion and having a minimum outer diameter b in the wheel pilot portion.

[0009] According to the present invention, it is possible to prevent or reduce sticking between the wheel pilot portion and the wheel, and to easily remove the wheel from the wheel pilot portion without using tools.

[0010] This is a side cross-sectional view showing a wheel bearing device. This is a side cross-sectional view showing the wheel pilot portion of the hub wheel. This is a side cross-sectional view showing the connection surface in the wheel pilot portion. This is a side cross-section showing the wheel pilot portion according to the second embodiment.

[0011] The embodiments for carrying out the present invention will be described below with reference to the attached drawings.

[0012] [Wheel Bearing Device] The wheel bearing device 1 shown in Figure 1 is one embodiment of the wheel bearing device according to the present invention, and is used to rotatably support a wheel in the suspension system of a vehicle such as an automobile.

[0013] The wheel bearing device 1 has a configuration referred to as the third generation, and comprises an outer ring 2 which is an outer member, a hub ring 3 and an inner ring 4 which are inner members, two rows of inner ball rows 5 and outer ball rows 6 which are rolling rows, an outer sealing member 9, a magnetic encoder 11, and a sensor holder 12.

[0014] In the following explanation, "inner side" refers to the vehicle body side of the wheel bearing device 1 when it is mounted on the vehicle body, and "outer side" refers to the wheel side of the wheel bearing device 1 when it is mounted on the vehicle body. "Axial direction" refers to the direction along the rotation axis X of the wheel bearing device 1. "Radial direction" refers to the direction perpendicular to the rotation axis X of the wheel bearing device 1. "Circumferential direction" refers to the direction along the arc centered on the rotation axis X of the wheel bearing device 1.

[0015] An inner opening 2a into which the sensor holder 12 can be fitted is formed at the inner end of the outer ring 2. An outer opening 2b into which the outer sealing member 9 can be fitted is formed at the outer end of the outer ring 2.

[0016] The sensor holder 12 is fitted into the inner opening 2a, which is the inner opening of the annular space S formed by the outer ring 2 and the hub ring 3, and the outer sealing member 9 is fitted into the outer opening 2b, which is the outer opening of the annular space S, thereby sealing the annular space S inside the bearing.

[0017] The inner circumferential surface of the outer ring 2 has an inner outer raceway surface 2c and an outer outer raceway surface 2d. The outer circumferential surface of the outer ring 2 has a vehicle body mounting flange 2e integrally formed thereon for attaching the outer ring 2 to the vehicle body side member.

[0018] The vehicle body mounting flange 2e is provided with bolt holes 2g into which fastening members (in this case, bolts) that fasten the vehicle body side member and the outer ring 2 are inserted. The outer ring 2 is located on the outer diameter side of the hub ring 3 and the inner ring 4.

[0019] The inner end of the hub wheel 3 has a small-diameter stepped portion 3a formed on its outer surface, which is smaller in diameter than the outer end. The outer end of the hub wheel 3 has a hub flange 3b integrally formed with it for attaching the wheel.

[0020] Multiple bolt holes 3f are formed in the hub flange 3b. Hub bolts 3e for fastening the hub wheel 3 to the wheel or brake components are press-fitted into the bolt holes 3f.

[0021] A wheel pilot portion 3g is formed on the outer side of the hub ring 3 beyond the hub flange 3b, into which the wheel WH of the wheel can be fitted. Between the wheel pilot portion 3g and the hub flange 3b in the axial direction of the hub ring 3, a brake rotor fitting portion 3j is formed into which the brake rotor BR can be fitted.

[0022] The outer surface of the hub ring 3 is provided with an inner raceway surface 3c on the outer side, facing the outer raceway surface 2d of the outer ring 2. In other words, the inner raceway surface 3c is formed on the outer side of the inner member by the hub ring 3. A seal land portion 3d of the outer side seal member 9 is formed on the base side of the hub flange 3b of the hub ring 3.

[0023] An inner ring 4 is provided on the small-diameter stepped portion 3a of the hub ring 3. The inner ring 4 is fixed to the small-diameter stepped portion 3a of the hub ring 3 by press-fitting and crimping. The inner ring 4 applies preload to the rolling rows, which consist of the inner ball row 5 and the outer ball row 6.

[0024] The inner ring 4 has an inner end face 4b at its inner end. A crimped portion 3h is formed at the inner end of the hub ring 3, which is crimped to the inner end face 4b of the inner ring 4.

[0025] The outer circumferential surface of the inner ring 4 is provided with an inner raceway surface 4a that faces the outer raceway surface 2c on the inner side of the outer ring 2. In other words, the inner raceway surface 4a is formed on the inner side of the inner member by the inner ring 4.

[0026] The inner ball row 5 and the outer ball row 6, which are rolling elements, are composed of multiple balls 7, which are rolling elements, held by a retainer 8.

[0027] The inner ball row 5 is rotatably sandwiched between the inner raceway surface 4a of the inner ring 4 and the inner outer raceway surface 2c of the outer ring 2. The outer ball row 6 is rotatably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer outer raceway surface 2d of the outer ring 2.

[0028] In other words, the inner ball row 5 and the outer ball row 6 are rotatably housed between the raceway surfaces of the outer member and the inner member. The outer ring 2 rotatably supports the hub ring 3 and the inner ring 4 via the inner ball row 5 and the outer ball row 6.

[0029] In the wheel bearing device 1, a double-row angular contact ball bearing is constructed from an outer ring 2, a hub ring 3 and an inner ring 4, an inner ball row 5, and an outer ball row 6. Alternatively, the wheel bearing device 1 may be configured with a double-row tapered roller bearing instead of the double-row angular contact ball bearing.

[0030] A support ring 10 is fitted to the inner end of the inner ring 4. The support ring 10 comprises a cylindrical portion 10a that is press-fitted into the outer diameter of the inner ring 4, and a vertical plate portion 10b that extends inward from the inner end of the cylindrical portion 10a. A magnetic encoder 11 is integrally bonded to the inner side surface of the vertical plate portion 10b by vulcanization bonding.

[0031] The magnetic encoder 11 is made of synthetic rubber mixed with magnetic powder such as ferrite, and magnetic poles N and S are magnetized alternately at equal pitches in the circumferential direction. The magnetic encoder 11 is an example of an encoder.

[0032] A sensor holder 12 is fitted into the inner opening 2a of the outer ring 2 so as to close the inner opening 2a. The sensor holder 12 is located on the inner side of the inner ring 4. A rotational speed sensor 13 is mounted on the sensor holder 12 at a position opposite the magnetic encoder 11.

[0033] The rotational speed sensor 13 and the magnetic encoder 11 are positioned opposite each other with a gap in the axial direction. The rotational speed sensor 13 is capable of detecting the displacement of the magnetic encoder 11, and by detecting the displacement of the magnetic encoder 11 using the rotational speed sensor 13, it is possible to detect the rotational speed of the inner ring 4. The rotational speed sensor 13 is a sensor that detects the displacement of the encoder.

[0034] [Wheel Pilot Section] As shown in Figure 2, the wheel pilot section 3g has a large diameter section 31 and a small diameter section 32.

[0035] The large-diameter portion 31 is the part into which the wheel WH of the wheel is fitted. The large-diameter portion 31 has an outer diameter a. The outer diameter a is the maximum outer diameter of the wheel pilot portion 3g (hereinafter, "outer diameter a" will also be referred to as "maximum outer diameter a"). In other words, the large-diameter portion 31 is the part of the wheel pilot portion 3g that fits with the wheel and has the maximum outer diameter a.

[0036] The large-diameter portion 31 has a first outer peripheral surface 31a. The first outer peripheral surface 31a is a surface parallel to the axial direction. The outer diameter a of the large-diameter portion 31 is the diameter of the first outer peripheral surface 31a.

[0037] The axial length of the wheel pilot portion 3g is L. The axial length L is the length from the outer end of the wheel pilot portion 3g to the brake rotor fitting portion 3j.

[0038] The axial distance between the outer end of the wheel pilot portion 3g and the inner end of the first outer peripheral surface 31a is c.

[0039] The small-diameter portion 32 is located on the inner side of the large-diameter portion 31. The small-diameter portion 32 has an outer diameter b. The outer diameter b is the minimum outer diameter of the wheel pilot portion 3g (hereinafter, "outer diameter b" will also be referred to as "minimum outer diameter b").

[0040] The small-diameter portion 32 has a second outer circumferential surface 32a. The second outer circumferential surface 32a is a surface parallel to the axial direction. The outer diameter b of the small-diameter portion 32 is the diameter of the second outer circumferential surface 32a.

[0041] The wheel pilot portion 3g has a connecting surface 33. The connecting surface 33 is the surface that connects the first outer peripheral surface 31a of the large diameter portion 31 and the second outer peripheral surface 32a of the small diameter portion 32.

[0042] As shown in Figure 3, the connecting surface 33 has an inclined surface 331 and an arcuate surface 332. The inclined surface 331 is formed continuously with the inner side end of the first outer peripheral surface 31a. The inclined surface 331 is an inclined surface that decreases in diameter as it approaches the inner side.

[0043] The arc surface 332 connects the inclined surface 331 and the second outer peripheral surface 32a. The arc surface 332 is formed in an arc shape when viewed from the circumferential direction. The arc shape of the arc surface 332 is an arc shape that is concave toward the inner diameter side. By connecting the inclined surface 331 and the second outer peripheral surface 32a with the arc surface 332, it is possible to relieve stress concentration at the boundary portion between the inclined surface 331 and the second outer peripheral surface 32a.

[0044] By arranging the small diameter portion 32 on the inner side of the large diameter portion 31, the wheel pilot portion 3g has a shape in which a concave portion recessed more on the inner diameter side than the first outer peripheral surface 31a is formed on the inner side of the large diameter portion 31.

[0045] [Relationship between the maximum outer diameter a and the minimum outer diameter b] The maximum outer diameter a of the large diameter portion 31 is larger than the minimum outer diameter b of the small diameter portion 32. That is, the large diameter portion 31 is formed to have a larger diameter than the small diameter portion 32.

[0046] Since the large diameter portion 31 is formed to have a larger diameter than the small diameter portion 32, when the wheel WH is fitted to the wheel pilot portion 3g, the inner peripheral surface of the wheel WH and the first outer peripheral surface 31a of the large diameter portion 31 come into contact, and a gap is generated between the inner peripheral surface of the wheel WH and the second outer peripheral surface 32a of the small diameter portion 32.

[0047] Therefore, the contact area between the wheel pilot portion 3g and the wheel WH can be reduced, and sticking between the wheel pilot portion 3g and the wheel WH can be prevented or reduced. As a result, it becomes possible to easily remove the wheel WH from the wheel pilot portion 3g without using tools.

[0048] Also, in the wheel pilot portion 3g, the maximum outer diameter a and the minimum outer diameter b have a relationship of 0.2 mm < a - b ≤ 1.0 mm. That is, the difference between the maximum outer diameter a and the minimum outer diameter b is larger than 0.2 mm and 1.0 mm or less.

[0049] As a result, the size of the gap between the inner circumferential surface of the wheel WH and the second outer circumferential surface 32a of the small diameter portion 32, which occurs when the wheel WH is fitted into the wheel pilot portion 3g, is greater than 0.1 mm and less than or equal to 0.5 mm. Therefore, it is possible to effectively reduce the contact area between the wheel pilot portion 3g and the wheel WH.

[0050] In this case, if the difference between the maximum outer diameter a and the minimum outer diameter b is 0.2 mm or less, a sufficiently large gap cannot be formed between the inner circumferential surface of the wheel WH and the second outer circumferential surface 32a of the small diameter portion 32, and thus, adhesion between the wheel pilot portion 3g and the wheel WH cannot be effectively prevented or reduced.

[0051] On the other hand, if the difference between the maximum outer diameter a and the minimum outer diameter b exceeds 1.0 mm, the minimum outer diameter b of the small diameter portion 32 may become too small, potentially resulting in insufficient strength in the wheel pilot portion 3g.

[0052] Therefore, in the hub wheel 3, it is preferable that the maximum outer diameter a and minimum outer diameter b of the wheel pilot portion 3g have the relationship 0.2 mm < a - b ≤ 1.0 mm.

[0053] Furthermore, in the wheel pilot portion 3g, a small-diameter portion 32 is located on the inner side of the large-diameter portion 31, which is recessed inward from the first outer peripheral surface 31a. This makes it possible to reduce the thickness of the portion of the hub wheel 3 where the small-diameter portion 32 is formed. This makes it possible to reduce the weight of the hub wheel 3.

[0054] Furthermore, in configurations where the wheel pilot portion 3g and the wheel WH are in overall contact, adhesion between the wheel pilot portion 3g and the wheel WH may be prevented by applying an anti-sticking paint to the contact surface between the wheel pilot portion 3g and the wheel WH.

[0055] However, by providing a large-diameter portion 31 and a small-diameter portion 32, as in the wheel pilot portion 3g of this embodiment, and configuring it so that only the large-diameter portion 31 contacts the wheel WH, it becomes unnecessary to apply an anti-sticking paint to the wheel pilot portion 3g.

[0056] [Relationship between axial distance c and axial length L] In the hub wheel 3, the axial distance c between the outer end of the wheel pilot portion 3g and the inner end of the first outer peripheral surface 31a, and the axial length L of the wheel pilot portion 3g have the relationship L / 4 ≤ c ≤ L / 2. In other words, the axial distance c is set to be at least one-quarter and at least half the length of the axial length L.

[0057] By setting the axial distance c and axial length L to have this relationship, the contact area between the wheel pilot portion 3g and the wheel WH can be made to an appropriate size, making it possible to effectively prevent or reduce sticking between the wheel pilot portion 3g and the wheel WH.

[0058] Here, if the axial distance c becomes smaller than one-quarter of the axial length L, the contact area between the wheel pilot portion 3g and the wheel WH becomes too small, and there is a risk that when the wheel WH is fitted into the wheel pilot portion 3g, the wheel WH will be mounted in an inclined position with respect to the axial direction.

[0059] On the other hand, if the axial distance c becomes larger than half of the axial length L, the contact area between the wheel pilot portion 3g and the wheel WH may become too large, making it impossible to adequately prevent or reduce sticking between the wheel pilot portion 3g and the wheel WH.

[0060] Therefore, in the hub wheel 3, it is preferable that the axial distance c and axial length L of the wheel pilot portion 3g have the relationship L / 4 ≤ c ≤ L / 2.

[0061] [Inclination angle of the inclined surface on the connection surface with respect to the axial direction] In the wheel pilot section 3g, the inclination angle θ1 of the inclined surface 331 on the connection surface 33 with respect to the axial direction is set to be 10° or more and 90° or less.

[0062] By setting the inclination angle θ1 of the inclined surface 331 within this range, it becomes possible to secure the difference between the maximum outer diameter a and the minimum outer diameter b without unnecessarily increasing the axial length L of the wheel pilot portion 3g. This makes it possible to prevent or reduce sticking between the wheel pilot portion 3g and the wheel WH while keeping the axial length of the hub wheel 3 compact.

[0063] Here, if the inclination angle θ1 becomes less than 10°, the axial length L of the wheel pilot portion 3g required to secure the difference between the maximum outer diameter a and the minimum outer diameter b will increase, which may cause the hub wheel 3 to become larger in the axial direction.

[0064] On the other hand, when the inclination angle θ1 becomes greater than 90°, the inner end of the first outer peripheral surface 31a of the large diameter portion 31 located on the outer diameter side is located on the inner side than the outer end of the second outer peripheral surface 32a of the small diameter portion 32 located on the inner diameter side. As a result, the inclined surface 331 becomes an undercut when machining the wheel pilot portion 3g, making the machining of the wheel pilot portion 3g more complicated.

[0065] Therefore, in the wheel pilot section 3g, it is preferable to set the inclination angle θ1 to be 10° or more and 90° or less. When the inclination angle θ1 of the inclined surface 331 is 90°, the inclined surface 331 becomes a surface perpendicular to the axial direction.

[0066] [Second Embodiment of Wheel Pilot Section] The wheel pilot section 3g can also be configured as shown in Figure 4, wheel pilot section 3gA.

[0067] The wheel pilot portion 3gA has a tapered surface 35. The tapered surface 35 is formed from the outer end to the inner end of the wheel pilot portion 3gA. The tapered surface 35 is an inclined surface that decreases in diameter towards the inner side.

[0068] The outer end of the tapered surface 35 is a large-diameter portion 351 having the maximum outer diameter a in the wheel pilot portion 3gA. The inner end of the tapered surface 35 is a small-diameter portion 352 having the minimum outer diameter b in the wheel pilot portion 3gA. The axial length of the wheel pilot portion 3gA is L.

[0069] When the wheel WH is fitted into the wheel pilot portion 3gA, the inner circumferential surface of the wheel WH comes into contact with the large diameter portion 351, and a gap is created between the wheel pilot portion 3gA on the inner side of the large diameter portion 351 and the inner circumferential surface of the wheel WH. The gap between the wheel pilot portion 3gA and the inner circumferential surface of the wheel WH increases as it moves towards the inner side.

[0070] Therefore, the contact area between the wheel pilot portion 3gA and the wheel WH can be reduced, preventing or reducing sticking between the wheel pilot portion 3gA and the wheel WH, and making it possible to easily remove the wheel WH from the wheel pilot portion 3gA.

[0071] [Inclination angle of the tapered surface in the wheel pilot section with respect to the axial direction] In the wheel pilot section 3gA, the inclination angle θ2 of the tapered surface 35 with respect to the axial direction is set to be 2° or more and 5° or less.

[0072] By setting the inclination angle θ2 of the tapered surface 35 within this range, the contact area between the wheel pilot portion 3gA and the wheel WH can be reduced, thereby preventing or reducing sticking between the wheel pilot portion 3g and the wheel WH.

[0073] Here, if the inclination angle θ2 becomes less than 2°, it becomes impossible to form a sufficient gap between the wheel pilot portion 3gA and the wheel WH, making it difficult to effectively prevent or reduce adhesion between the wheel pilot portion 3gA and the wheel WH.

[0074] On the other hand, if the inclination angle θ2 becomes greater than 5°, the minimum outer diameter b in the small diameter portion 352 may become too small, potentially making it impossible to ensure sufficient strength in the wheel pilot portion 3gA.

[0075] Therefore, in the wheel pilot section 3gA, it is preferable to set the inclination angle θ2 to be 2° or more and 5° or less.

[0076] Furthermore, in the wheel pilot section 3gA, the inclination angle θ2 of the tapered surface 35 is set to be smaller than the inclination angle θ1 of the inclined surface 331 in the wheel pilot section 3g. Therefore, in the region of the tapered surface 35 closest to the large diameter section 351, there is a risk that a sufficient gap cannot be secured between the inner circumferential surface of the wheel WH and the tapered surface 35.

[0077] However, in the wheel pilot portion 3gA, only a very small area of ​​the large diameter portion 351 and the inner circumferential surface of the wheel WH come into contact. Therefore, it is possible to have a long axial area where the wheel pilot portion 3gA and the wheel WH do not come into contact.

[0078] Therefore, the area where adhesion is likely to occur between the wheel pilot portion 3gA and the inner circumferential surface of the wheel WH can be kept generally small, making it possible to effectively prevent or reduce adhesion between the wheel pilot portion 3gA and the wheel WH.

[0079] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these embodiments, but is merely illustrative. It can be implemented in various other forms without departing from the spirit of the invention, and the scope of the present invention is indicated by the claims, and further includes all modifications within the meaning and scope of equivalents as described in the claims.

[0080] This invention can be used in wheel bearing devices.

[0081] 1 Wheel bearing device 2 Outer ring 2c Outer raceway surface (inner side) 2d Outer raceway surface (outer side) 3 Hub ring 3b Hub flange 3c Inner raceway surface (of the hub ring) 3g, 3gA Wheel pilot section 3j Brake rotor fitting section 4 Inner ring 4a Inner raceway surface (of the inner ring) 5 Inner ball row 6 Outer ball row 31, 351 Large diameter section 31a First outer surface 32, 352 Small diameter section 32a Second outer surface 33 Connecting surface 35 Tapered surface 331 Inclined surface 332 Arc surface a Maximum outer diameter (of the wheel pilot section) b Minimum outer diameter (of the wheel pilot section) c Axial distance (between the outer end of the wheel pilot section and the inner end of the first outer surface) L Axial length (of the wheel pilot section) BR Brake rotor WH Wheel θ1 Angle of inclination (with respect to the axial direction of the inclined surface) θ2 Angle of inclination (with respect to the axial direction of the tapered surface)

Claims

1. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; a hub ring having a hub flange at its outer end for supporting a wheel; and an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, with at least one inner ring press-fitted to the inner side of the hub ring beyond the hub flange; and double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member, wherein the hub ring has a wheel pilot portion located on the outer side of the hub flange and into which a wheel can be fitted; and a brake rotor fitting portion located between the wheel pilot portion and the hub flange and into which a brake rotor can be fitted; and the wheel pilot portion has a large diameter portion having a maximum outer diameter a that fits with the wheel in the wheel pilot portion, and a small diameter portion located on the inner side of the large diameter portion and having a minimum outer diameter b in the wheel pilot portion.

2. The wheel bearing device according to claim 1, wherein the relationship between the maximum outer diameter a and the minimum outer diameter b is 0.2 mm < a - b ≤ 1.0 mm.

3. The wheel bearing device according to claim 1 or claim 2, wherein the large-diameter portion has a first outer peripheral surface parallel to the axial direction, and the axial distance c between the outer end of the wheel pilot portion and the inner end of the first outer peripheral surface and the axial length L of the wheel pilot portion are related by L / 4 ≤ c ≤ L / 2.

4. The wheel bearing device according to claim 1 or claim 2, wherein the large diameter portion has a first outer peripheral surface parallel to the axial direction, the small diameter portion has a second outer peripheral surface parallel to the axial direction, the wheel pilot portion has a connecting surface that connects the first outer peripheral surface and the second outer peripheral surface, the connecting surface has an inclined surface formed continuously with the first outer peripheral surface and decreasing in diameter toward the inner side, and an arc surface that connects the inclined surface and the second outer peripheral surface and is formed in an arc shape when viewed from the circumferential direction, and the inclination angle θ1 of the inclined surface with respect to the axial direction is 10° or more and 90° or less.

5. The wheel bearing device according to claim 1, wherein the outer circumferential surface of the wheel pilot portion is formed from the outer end to the inner end of the wheel pilot portion and has a tapered surface that decreases in diameter from the outer side to the inner side, the outer end of the tapered surface is the large diameter portion having the maximum outer diameter a, and the inner end of the tapered surface is the small diameter portion having the minimum outer diameter b.

6. The wheel bearing device according to claim 5, wherein the inclination angle θ2 of the tapered surface with respect to the axial direction is 2° or more and 5° or less.

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