Wheel

Abstract

To provide a wheel capable of suppressing fastening looseness between a hub and the wheel.SOLUTION: A pneumatic tire includes a rim part to which a tire is attached, and a disk part 12 attached to the inside of the rim part, the disk part 12 includes a hub attachment part 22 positioned at a rotation center, and the hub attachment part 22 includes a plurality of bolt holes 25 for fastening the hub attachment part 22 to a hub. A side surface constituting the bolt hole 25 has a seat surface part 25b for holding fastening by contacting with a nut, and a shape of a hole peripheral inner surface 31 connected to a hub installing surface 32 contacting with the hub from an inside end of the bolt hole 25 has an inclined linear shape in a cross-sectional view in a surface on the inside in the vehicle widthwise direction in the hub installing part 22.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A wheel, which is a component of a vehicle, includes a wheel. The wheel includes a rim portion on which a tire is mounted and a disc portion to which a vehicle hub is attached. The disc portion includes a hub mounting surface with bolt holes on its inner surface in the vehicle width direction. When nuts are fastened from the outer side in the vehicle width direction to bolts protruding from the hub, the hub mounting surface is tightly attached to the hub. The wheel is then fixed to the hub.

[0003] Wheels are elements that support the vehicle load, so they need to be strong (see Patent Document 1). High strength wheels are achieved by increasing the thickness of the rim and disc components of the wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-67011 Summary of the Invention [Problem to be solved by the invention]

[0005] However, electric vehicles, self-driving vehicles, and other vehicles are heavier than conventional vehicles. Therefore, these types of heavy vehicles place a heavy load on the wheels because they need to be equipped with batteries and equipment for autonomous driving.

[0006] When conventional wheels are used on heavy vehicles, the hub mounting area, including the bolt holes, can be deformed under heavy loads, which can cause the bolt and nut fastening to loosen. [Means for solving the problem]

[0007] A wheel that solves the above problem comprises a rim portion to which a tire is attached, and a disc portion located inside the rim portion, the disc portion comprising a hub mounting portion located at the center of rotation, the hub mounting portion comprising a plurality of bolt holes for fastening the hub mounting portion to the hub, the side surfaces that form the bolt holes comprising seat portions that contact and maintain the fastening with fastening members, and on the inner surface of the hub mounting portion in the vehicle width direction, the shape of the inner surface around the hole that connects the inner end of the bolt hole to the hub mounting surface that contacts the hub has a linear shape that slopes downward towards the inside in the vehicle width direction in a cross-sectional view.

[0008] According to the above configuration, when a nut, which is an example of a fastening member, is fastened to a bolt, the seating surface is sandwiched between the hub and the nut, causing the hub mounting surface to tightly contact the hub. When the nut is tightened, the sandwiching width of the seating surface shortens, generating a reaction force (a force toward the outside in the vehicle width direction) on the hub mounting surface that tries to return the sandwiching width to its original state. This reaction force also acts as a force pushing the nut (a force toward the inside in the vehicle width direction), generating a force that stretches the length of the bolt fastened to the nut. Meanwhile, the bolt generates an axial force (a force that pulls the fastened nut and hub together) that tries to return to its original length. This allows the bolt and nut to maintain tight contact with the hub mounting surface. In other words, the bolt axial force and its reaction force balance each other during fastening, maintaining the tightening torque.

[0009] Even in the case of high-load tightening with increased bolt axial force, the compressive load on the bearing surface is generated by efficiently converting the amount of tightening of the nut (tightening torque) into axial force on the bolt. Furthermore, the compressive load acts toward the base of the hole periphery along the inner surface of the hole periphery, which has a linear cross section, and is efficiently transmitted to the bearing surface. This suppresses deformation of the open end of the bolt hole, including the bearing surface, toward the hub, making it possible to accommodate high-load tightening.

[0010] In the above-mentioned wheel, it is preferable that the shape of the outer surface around the hole opposite the inner surface around the hole on the outer side of the hub mounting portion in the vehicle width direction has a bulging shape that bulges outward in the vehicle width direction when viewed in cross section.

[0011] According to the above configuration, the direction along the curved outer surface around the hole, on which the compressive load and the reaction force from the fastening seat act, is close to or coincides with the direction of the load when the vehicle is running (when the wheel is rotating) and when the vehicle is turning. The portion of the outer surface around the hole has a bulging shape, making it thicker than other portions. Therefore, the reaction force against the rotational load when the vehicle is running (when the wheel is rotating) and when the vehicle is turning can be increased in the portion of the outer surface around the hole.

[0012] In the above-described wheel, the bulging portion is preferably thicker than the other portions of the hub attachment portion. With the above configuration, the thicker portion is limited to only a portion of the hub attachment portion. This allows for a lightweight wheel design.

[0013] In the wheel described above, the bulging shape is preferably formed by compression from the open end of the bolt hole outward in the radial direction of the bolt hole. With this configuration, a thick bulging shape can be easily formed by compression from the open end of the bolt hole.

[0014] In the wheel described above, it is preferable that compressive residual stress be applied between the inner surface around the hole and the outer surface around the hole. With the above configuration, the bulged portion has compressive residual stress, which increases its strength. As a result, deformation of the hub attachment portion can be suppressed, and fastening performance can be improved. [Effects of the Invention]

[0015] According to the present invention, loosening of the fastening between the hub and the wheel can be suppressed. [Brief explanation of the drawings]

[0016] [Figure 1]FIG. 1 is a perspective view of a vehicle wheel according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a mounting state of a vehicle wheel and a hub in the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view illustrating a load applied to a hub mounting portion of the vehicle wheel in the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view illustrating a load applied to a hub mounting portion of a vehicle wheel serving as a reference example of the first and second embodiments. [Figure 5] FIG. 5 is a cross-sectional view illustrating a load applied to a hub mounting portion of a vehicle wheel in the second embodiment. [Figure 6] FIG. 6 is a cross-sectional perspective view showing an example in which sub-ribs are provided in the first and second embodiments. [Figure 7] FIG. 7 is a cross-sectional perspective view showing an example in which the first and second embodiments are attached to the hub with bolts. DETAILED DESCRIPTION OF THE INVENTION

[0017] A wheel to which the present invention is applied will be described below with reference to the drawings. First Embodiment <Wheel configuration> As shown in Figures 1 and 2, a vehicle wheel 10 according to the first embodiment is a wheel used in passenger cars and the like. The wheel 10 is a steel wheel or an aluminum wheel. However, the wheel 10 is not limited to these materials and may be made of other materials. In this embodiment, the wheel 10 is a steel wheel, and since it is manufactured by press forming, it is designed by imparting a shape to a plate material of a certain thickness. This wheel 10 includes a rim portion 11 to which a tire is attached, and a disc portion 12 located inside the rim portion 11. The disc portion 12 is welded to the annular rim portion 11 to form the wheel 10.

[0018] The rim portion 11 includes an inner flange portion 13, an inner bead seat portion 14, a drop portion 15, an outer bead seat portion 16, and an outer flange portion 17. The inner flange portion 13 and the inner bead seat portion 14 are located on the inner side (in) of the outer bead seat portion 16 and the outer flange portion 17 in the vehicle width direction when the wheel 10 is mounted on the vehicle. In other words, the outer bead seat portion 16 and the outer flange portion 17 are located on the outer side (out) of the inner flange portion 13 and the inner bead seat portion 14 in the vehicle width direction when the wheel 10 is mounted on the vehicle.

[0019] The disk portion 12 includes a hub hole 21, a hub attachment portion 22, a disk flange portion 23, and a hat portion 24. The hub hole 21 is provided in the center of the disk portion 12 in the disk radial direction (wheel radial direction).

[0020] As shown in Figures 2 and 3, the hub mounting portion 22 is provided around the hub hole 21. The hub mounting portion 22 is located at the center of rotation by the hub 26 and lies in a plane perpendicular or approximately perpendicular to the disk axial direction (wheel axial direction) DA. The hub mounting portion 22 is provided with a plurality of bolt holes 25. The bolt holes 25 are provided at equal intervals in the disk circumferential direction (wheel circumferential direction). Bolts 27 extending from the hub 26 are inserted into the bolt holes 25. Nuts 28 are then fastened to the bolts 27. In this way, the wheel 10 is fixed to the hub 26. The bolts 27 and nuts 28 are fastening members for attaching the wheel to the hub 26.

[0021] The side surface that constitutes the bolt hole 25 includes a linear portion 25a and a seating surface portion 25b. In the bolt hole 25, the linear portion 25a is located on the inner side (in) in the vehicle width direction, and the seating surface portion 25b is located on the outer side (out) in the vehicle width direction. The seating surface portion 25b has a larger diameter than the linear portion 25a. The seating surface portion 25b may be a spherical seat with a curved cross-sectional shape or a linear tapered seat. When the wheel 10 is fixed to the hub 26, the tip of the bolt 27 is located on the outer side (out) in the vehicle width direction, and the nut 28 is fastened from the tip. The nut seat 28a of the nut 28 has a shape that corresponds to the seating surface portion 25b and contacts the seating surface portion 25b. When the nut 28 is tightened, the nut seat 28a presses the seating surface portion 25b.

[0022] The wheel may be attached to the hub using a bolt as a fastening member. The bolt is a member having a polygonal nut head, which serves as the bolt head, at one end of a shank having a threaded groove. The nut head has a nut seat shaped to correspond to the seat surface portion 25b at the boundary with the shank. The bolt may not have a nut head at one end of the shank, but may have a circular or polygonal nut head with an engagement opening such as a hexagonal hole.

[0023] The disk flange portion 23 (see FIG. 1) is provided in the disk circumferential direction. The disk flange portion 23 is on the same circumference. However, the disk flange portion 23 does not have to be provided on the same circumference. The disk flange portion 23 is the outer end portion in the disk radial direction, and extends in a direction parallel to the disk axial direction DA. The disk flange portion 23 is fitted with and welded to the rim portion 11. The disk flange portion 23 may be welded to the rim portion 11 over the entire area of ​​the disk flange portion 23 in the disk circumferential direction, or may be welded intermittently. The disk portion 12 is fixed to the rim portion 11 by the disk flange portion 23.

[0024] The hat portion 24 is provided between the hub mounting portion 22 and the disk flange portion 23 in the disk radial direction, and connects the hub mounting portion 22 and the disk flange portion 23 in the disk radial direction. The hat portion 24 has a portion located outward in the vehicle width direction from the hub mounting portion 22 and the disk flange portion 23. For example, the top of the hat portion 24 is located outward in the vehicle width direction from the hub mounting portion 22 and the disk flange portion 23. The hat portion 24 has a mountain shape that bulges outward in the vehicle width direction from the hub mounting portion 22.

[0025] <Configuration of hub mounting part> As shown in Fig. 3, the surface of hub mounting portion 22 on the inner side in the vehicle width direction is provided with a hole peripheral inner surface 31 and a hub mounting surface 32 around bolt hole 25. Hub mounting surface 32 is the surface that comes into contact with hub 26. The inner end of bolt hole 25 on the inner side in the vehicle width direction is located further outward in the vehicle width direction than hub mounting surface 32. Therefore, bolt hole 25 is located at a distance from hub 26.

[0026] The portion connecting the inner end of bolt hole 25 on the inner side in the vehicle width direction and the inner circumferential edge of hub mounting surface 32 is hole peripheral inner surface 31. Hole peripheral inner surface 31 is configured as an inclined surface connecting the inner end of bolt hole 25 on the inner side in the vehicle width direction and the inner circumferential edge of hub mounting surface 32. In a cross-sectional view, hole peripheral inner surface 31 has a linear shape that is inclined downward toward the inner side in the vehicle width direction as it extends toward the outer periphery.

[0027] In the hub mounting portion 22, the surface on the outer side in the vehicle width direction (out) has a hole peripheral outer surface 33 around the bolt hole 25. The hole peripheral outer surface 33 is the surface opposite to the hole peripheral inner surface 31, and is configured as an inclined surface connecting the outer end of the bolt hole 25 on the outer side in the vehicle width direction (out) to the inner circumferential end of the hat portion 24. In a cross-sectional view, the hole peripheral outer surface 33 has a linear shape that is inclined downward toward the inner side in the vehicle width direction as it extends toward the outer periphery. The hole peripheral outer surface 33 may be a surface parallel to the hole peripheral inner surface 31. The portion sandwiched between the hole peripheral inner surface 31 and the hole peripheral outer surface 33 is a hole peripheral portion 34.

[0028] <Operation of the First Embodiment> As shown in FIG. 3 , when the nut 28 is fastened to the bolt 27, the bearing surface 25b is sandwiched between the hub 26 and the nut 28, thereby bringing the hub mounting surface 32 into tight contact with the hub 26. When the nut 28 is fastened to the bolt 27 in the direction of arrow 51, the sandwiching width of the bearing surface 25b is shortened, generating a reaction force (a force toward the outer side, out, in the vehicle width direction) of the hub mounting portion 22 that tries to return the sandwiching width to its original size. This reaction force also acts as a pushing force on the nut 28 (a force toward the inner side, in the vehicle width direction), generating a force that extends the length of the bolt 27 fastened to the nut 28. Meanwhile, the bolt 27 generates an axial force (a force that pulls the fastened nut 28 and the hub 26 against each other) that tries to return to its original length. This allows the bolt 27 and the nut 28 to maintain tight contact with the hub mounting portion 22 and the hub 26. That is, when fastened, the axial force of the bolt 27 and its reaction force are balanced, thereby maintaining the tightening torque.

[0029] Even in the case of high-load tightening with an increased axial force of bolt 27, compressive load 52 on bearing surface 25b is generated by efficiently converting the tightening amount (tightening torque) of nut 28 in the direction of arrow 51 into axial force of bolt 27. Compressive load 52 acts along hole peripheral inner surface 31 and hole peripheral outer surface 33, each of which has a linear cross section, toward base 35 of hole peripheral portion 34, and can be further dispersed by the Poisson effect (increased cross-sectional area subjected to compression). This makes it possible to suppress deformation of the open end of bolt hole 25, including bearing surface 25b, toward hub 26, enabling high-load tightening to be accommodated.

[0030] In contrast, Figure 4 shows a wheel hub mounting portion 36 according to a reference example. In the wheel hub mounting portion 36 according to the reference example, the surface on the vehicle widthwise inner side "IN" has a hole peripheral inner surface 37 that has a different shape from the above-mentioned hole peripheral inner surface 31. The hole peripheral inner surface 37 is formed by a curved surface that connects the inner end of the bolt hole 25 on the vehicle widthwise inner side "IN" to the inner circumferential end of the hub mounting surface 32. In other words, in a cross-sectional view, the hole peripheral inner surface 37 has a curved shape that slopes downward toward the vehicle widthwise inner side "IN" as it approaches the outer periphery.

[0031] In the hub mounting portion 36, the surface on the vehicle widthwise outer side (out) has a hole peripheral outer surface 38, which has a different shape from the above-mentioned hole peripheral outer surface 33. The hole peripheral outer surface 38 is configured as a curved surface connecting the outer end of the bolt hole 25 on the vehicle widthwise outer side (out) and the inner circumferential end of the hat portion 24. That is, in a cross-sectional view, the hole peripheral outer surface 38 has a curved shape that slopes downward toward the vehicle widthwise inner side (in) as it approaches the outer periphery. The hole peripheral outer surface 38 is a portion that connects to the inner circumferential end of the hat portion 24, and is a surface that corresponds to and is parallel to the hole peripheral inner surface 37. The portion sandwiched between the hole peripheral inner surface 37 and the hole peripheral outer surface 38 is a hole peripheral portion 39. The hole peripheral portion 39 is a curved portion.

[0032] When nut 28 is tightened onto bolt 27, bearing surface portion 25b is sandwiched between hub 26 and the tightened nut 28, so that hub mounting surface 32 is in intimate contact with hub 26. When nut 28 is tightened onto bolt 27 in the direction of arrow 51, hole periphery 39 sinks in the direction of arrow 51, which is the tightening direction. Hole periphery 39 then displaces toward hub 26, with a portion located at the base of hub mounting portion 36 as fulcrum 53, and this displacement behaves like a bending beam and serves as a reaction force to the axial force of bolt 27. At the same time, when nut 28 is tightened in the direction of arrow 51, nut 28 pushes bearing surface portion 25b outward, applying a compressive load 54 in a direction following the curved shape.

[0033] In the case of high-load fastening with increased axial force of bolt 27, the amount of tightening of the nut (tightening torque), which acts as a bending shear force on hole peripheral portion 39, increases, resulting in a greater displacement from fulcrum 53 toward hub 26. If hole peripheral portion 39 exceeds the elastic range of the material and undergoes plastic deformation, the reaction force due to elastic deformation cannot be efficiently obtained, which causes nut 28 to loosen and hinders high-load fastening, which is a stronger fastening. In this regard, in the first embodiment shown in Figure 3, hole peripheral portion 34 sandwiched between hole peripheral inner surface 31 and hole peripheral outer surface 33 is less likely to plastically deform in the direction of arrow 51, and the reaction force due to elastic deformation can be obtained more efficiently, making high-load fastening possible compared to the reference example.

[0034] The curved direction in which the compressive load 54 and the reaction force from the fastening seat act is close to or coincides with the direction of the load (arrow 56) when the vehicle is running (when the wheel is rotating) and when the vehicle is turning. Therefore, the reference example can suppress deformation of the bearing surface of the hole peripheral portion 39 when the vehicle is running (when the wheel is rotating) and when the vehicle is turning. In this case, unlike fastening, the nut 28 moves along the arrow 56, and a load is applied to the hole peripheral portion 39 toward the hub hole 21 and the hat portion 24, causing it to deform. Because there is no constraint in the direction of the arrow 56, deformation is suppressed by the thickness of the hole peripheral portion 39 in the direction of the arrow 56.

[0035] <Effects of the first embodiment> The first embodiment described above can provide the following effects. (1-1) Even in the case of high-load fastening with increased bolt axial force, the compressive load 52 on the bearing surface 25b is efficiently converted into the axial force of the bolt 27 by the tightening amount (tightening torque) of the nut 28 in the direction of the arrow 51. The compressive load 52 acts along the hole peripheral inner surface 31 and the hole peripheral outer surface 33, which have linear cross sections, toward the base 35 of the hole peripheral portion 34, and the Poisson effect (increased cross-sectional area subjected to compression) further distributes the compressive load 52. This makes it possible to suppress deformation of the opening end of the bolt hole 25, including the bearing surface 25b, toward the hub 26, enabling high-load fastening to be accommodated.

[0036] Second Embodiment FIG. 5 shows a second embodiment of the wheel 10 . The hub mounting portion 40 in the second embodiment has a surface on the vehicle widthwise inner side (inside) that is provided with a hole peripheral inner surface 41 and a hub mounting surface 42 around the bolt hole 25. The hub mounting surface 42 is the surface that comes into contact with the hub 26. The hole peripheral inner surface 41 is formed as an inclined surface that connects the inner end of the bolt hole 25 on the vehicle widthwise inner side (inside) to the inner circumferential end of the hub mounting surface 42. In cross-sectional view, the hole peripheral inner surface 41 has a linear shape that is inclined downward toward the vehicle widthwise inner side (inside) as it extends toward the outer periphery. In other words, the hole peripheral inner surface 41 is the same as the hole peripheral inner surface 31 in the first embodiment.

[0037] In the hub mounting portion 40, the surface on the outer side in the vehicle width direction (out) has a hole peripheral outer surface 43 around the bolt hole 25. The hole peripheral outer surface 43 is configured as a curved surface that connects the outer end of the bolt hole 25 on the outer side in the vehicle width direction (out) and the inner circumferential end of the hat portion 24. In other words, in a cross-sectional view, the hole peripheral outer surface 43 has a curved shape that slopes downward toward the inner side in the vehicle width direction as it extends toward the outer periphery. The hole peripheral outer surface 43 is a portion that connects to the inner circumferential end of the hat portion 24. The portion sandwiched between the hole peripheral inner surface 41 and the hole peripheral outer surface 43 is the hole peripheral portion 44.

[0038] The hole peripheral portion 44 has a hole peripheral inner surface 41 with a linear cross section and a hole peripheral outer surface 43 with a curved cross section. Therefore, on the surface on the outer side in the vehicle width direction (out), the area around the bolt hole 25 has a bulging shape that bulges outward in the vehicle width direction (out). In other words, the thickness 46 of the hole peripheral portion 44 is thicker than other portions of the hub mounting portion 40. It is also thicker than other portions of the disk portion 12, such as the hat portion 24.

[0039] The disk portion 12 is formed by press-forming a material of a constant thickness into the hub mounting portion 22, disk flange portion 23, hat portion 24, etc. Then, compression is performed from the open end of the bolt hole 25 while the hole peripheral inner surface 41 is restrained with a mold so that the cross section is linear. This allows the hole peripheral outer surface 43 to be formed into a curved, bulging shape. Therefore, the bulging portion has compressive residual stress.

[0040] <Operation of the Second Embodiment> When the nut 28 is fastened to the bolt 27, the bearing surface 25b is sandwiched between the hub 26 and the nut 28, causing the hub mounting surface 42 to tightly contact the hub 26. When the nut 28 is fastened to the bolt 27 in the direction of arrow 51, the sandwiching width of the bearing surface 25b is shortened, generating a reaction force (a force toward the outside in the vehicle width direction, out) of the hub mounting portion 22 that tries to return the sandwiching width to its original size. This reaction force also acts as a pushing force on the nut 28 (a force toward the inside in the vehicle width direction, in), generating a force that extends the length of the bolt 27 fastened to the nut 28. Meanwhile, the bolt 27 generates a bolt axial force (a force that pulls the fastened nut 28 and hub 26 against each other) that tries to return the bolt 27 to its original length. As a result, the bolt 27 and the nut 28 maintain tight contact between the hub mounting portion 22 and the hub 26. In other words, when fastened, the axial force of the bolt 27 and its reaction force balance each other, thereby maintaining the tightening torque.

[0041] Even in the case of high-load tightening with increased axial force of the bolt 27, the compressive load 55 on the bearing surface portion 25b acts linearly along the hole peripheral inner surface 41, which has a linear cross section, toward the base 57 of the hole peripheral portion 44. At the same time, the compressive load 55 acts curvedly along the hole peripheral outer surface 43, which has a curved cross section. Here, the hole peripheral portion 44 is thicker than other portions of the disk portion 12, such as the hat portion 24, because the hole peripheral outer surface 43 has a bulged shape. Therefore, the hole peripheral portion 44 is less likely to be displaced in the direction of the arrow 51. This allows the compressive load 55 to be efficiently transmitted to the bearing surface portion 25b. This allows for high-load tightening. In other words, the problem with the high-load tightening in the reference example (FIG. 4) can be resolved.

[0042] Furthermore, the direction along the curved hole peripheral outer surface 43, on which the compressive load 55 and the reaction force from the fastening seat act (upper arrow 55), is close to or coincides with the direction of the load (arrow 56) when the vehicle is running (when the wheels are rotating) and turning. The hole peripheral portion 44 is thicker than other portions because the hole peripheral outer surface 43 has a bulging shape. Therefore, deformation of the seat surface of the hole peripheral portion 39 can be suppressed when the vehicle is running (when the wheels are rotating) and turning. This makes it difficult for the nut 28 to loosen.

[0043] <Effects of the second embodiment> The second embodiment described above can provide the following advantages. (2-1) Even in the case of high-load tightening with an increased axial force of the bolt 27, the compressive load 55 on the bearing surface portion 25b acts linearly toward the base 57 of the hole peripheral portion 44, along the hole peripheral inner surface 41, which has a linear cross section. At the same time, the compressive load 55 acts curvedly along the hole peripheral outer surface 43, which has a curved cross section. Here, because the hole peripheral outer surface 43 has a bulging shape and the hole peripheral inner surface 41 has a linear shape, the hole peripheral portion 44 is thicker than other portions of the disk portion 12, such as the hat portion 24. Therefore, the hole peripheral portion 44 is less likely to displace in the direction of the arrow 51. This allows the compressive load 55 to be efficiently transmitted to the bearing surface portion 25b. This allows for high-load tightening.

[0044] Additionally, the direction along the curved hole peripheral outer surface 43, along which the compressive load 55 and the reaction force from the fastening seat act (upper arrow 55), is close to or coincides with the load direction (arrow 56) during vehicle travel (wheel rotation) and vehicle cornering. The hole peripheral portion 44 is thicker than other portions due to the bulging shape of the hole peripheral outer surface 43. Therefore, deformation of the bearing surface of the hole peripheral portion 39 during vehicle travel (wheel rotation) and vehicle cornering can be suppressed. That is, during vehicle travel (wheel rotation) and vehicle cornering, the hub 26, bolt 27, and nut 28 move together in the direction of arrow 56. This causes the hub 26 to tilt, creating a gap between the hub mounting surface 32 and the hub 26. This causes the nut 28 to tilt in the same direction, destabilizing the fastening of the bolt 27 and the nut 28. At the same time, the nut 28 also tilts in the same direction. In this embodiment, the hole peripheral portion 44 is thick. This suppresses deformation of the bearing surface of the hole peripheral portion 39. As a result, loosening of the nut 28 can be suppressed.

[0045] (2-2) The outer surface 43 around the hole is made thicker than other parts. The thickened part is only part of the hub mounting portion 40. Therefore, the wheel 10 can be designed to be lightweight.

[0046] (2-3) The bulging shape of hole-periphery outer surface 43 can be easily formed into a thick bulging shape by compressing from the open end of bolt hole 25 outward in the radial direction of bolt hole 25. Specifically, the bulging shape can be formed by compressing hole-periphery inner surface 41 in a downward slant toward the inside in the vehicle width direction.

[0047] (2-4) The bulged portion has compressive residual stress, which increases its strength. As a result, deformation of the hub attachment portion 40 is suppressed, and fastening performance is improved.

[0048] The first and second embodiments can be modified as follows: The first and second embodiments and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0049] In the second embodiment, the bulging portion does not need to have residual compressive stress. Also, the method for forming the bulging portion is not limited to compression molding. In the first and second embodiments, as shown in Fig. 6, the hole peripheral outer surface 38 may not be directly connected to the inner peripheral end of the hat portion 24, and a sub-rib 61 formed of a recess may be present between them. In this case, the contact surface around the seat of the nut 28 and the hub 26 are not in partial contact with each other.

[0050] 7 shows a configuration in which a wheel 10 is attached to a hub 26 using a bolt 71 as a fastening member. The bolt 71 used here has a shank 72 with a threaded groove and a nut head 73 provided at one end of the shank 72. The nut head 73 is provided with a nut seat 74 at the boundary with the shank 72, the nut seat having a shape corresponding to the seating surface. The hub 26 is provided with a bolt hole 75 into which the shank 72 is fastened.

[0051] Even with this configuration, the wheel 10 can be attached by tightening the bolt 71 to the hub 26. The nut head 73 has a configuration similar to that of the nut 28 described in the first and second embodiments, and also includes a nut seat 74. Therefore, even when the bolt 71 is used, the same effects as those of the first and second embodiments can be obtained.

[0052] The wheels may be wheels used for commercial vehicles, etc., or may be wheels used for passenger cars, etc. In addition, the wheels may be applied to wheels of work vehicles, bicycle wheels, and railway wheels. [Explanation of symbols]

[0053] 10...Wheels 11...Rim section 12...Disc section 21...hub hole 22...Hub mounting part 23...Disc flange 24...Hat section 25...Bolt hole 25a...Straight section 25b… Seat part 26...Hub 27...Volts 28...Nut 28a...Nut seat 31...Inner surface around the hole 32...Hub mounting surface 33...Outer surface around the hole 34...Area surrounding the hole 35...root

Claims

1. The tire has a rim portion to which the tire is attached, and a disc portion located inside the rim portion, The disk portion includes a hub mounting portion located at the center of rotation, the hub mounting portion has a plurality of bolt holes for fastening the hub mounting portion to the hub, The side surface of the bolt hole includes a bearing surface portion that contacts and holds a fastening member, On the inner surface of the hub attachment portion in the vehicle width direction, the shape of the inner surface around the hole that connects from the inner end of the bolt hole to the hub attachment surface that contacts the hub has a linear shape that is inclined downward toward the inner side in the vehicle width direction in a cross-sectional view. wheel.

2. In a vehicle width direction outer surface of the hub attachment portion, the shape of the hole peripheral outer surface opposite to the hole peripheral inner surface has a bulging shape that bulges outward in the vehicle width direction in a cross-sectional view.

10. The wheel of claim 1.

3. The bulging shape is thicker than other portions of the hub mounting portion.

3. The wheel of claim 2.

4. The bulging shape is formed by compression from the open end of the bolt hole toward the outside in the radial direction of the bolt hole.

4. The wheel of claim 3.

5. A compressive residual stress is applied between the inner surface around the hole and the outer surface around the hole.

5. The wheel of claim 4.

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