Wheel bearing device

Abstract

This bearing device 10 comprises: an outer ring 12; an inner member 11 having, on one side thereof in an axial direction, a flange part 27 provided with a plurality of bolt holes 28 for fixing a vehicle wheel, and tap holes 38 for fixing a brake rotor; and a plurality of balls 13 disposed between the outer ring 12 and the inner member 11. The flange part 27 includes: a thin wall part 34 formed in a first region which is a region between bolt holes 28 circumferentially adjacent to each other and has through-holes 40 passing through in the axial direction, and does not have the tap holes 38, and in a second region having the tap holes 38, a first thick wall part 33 including a portion in which regions around the bolt holes 28 are raised from the thin wall part 34 toward the other side in the axial direction; and a second thick wall part 37 in which regions around the tap holes 38 are raised from the thin wall part 34 of the second region toward the other side in the axial direction.

Description

[Technical field]

[0001] The present disclosure relates to a wheel bearing device. [Background technology]

[0002] A wheel bearing device called a hub unit is used to attach wheels and brake discs to the body of an automobile (see, for example, Patent Document 1). The wheel bearing device includes an inner shaft having a flange portion for attaching a wheel or the like. FIG. 9 is a perspective view of a conventional inner shaft 90. As shown in FIG. 9, the inner shaft 90 in the conventional wheel bearing device has a shaft-shaped main body portion 91 and a flange portion 92 provided on one axial side of the main body portion 91. A plurality of bolt holes 93 for attaching wheels (not shown) are formed in the flange portion 92.

[0003] The flange portion 92 has a flange base 95 having a circular cross section that is continuous with the main body portion 91, a first thick-walled portion 96 that is provided radially outward of the flange base 95 at equal intervals in the circumferential direction and has bolt holes 93 formed therein, and a thin-walled portion 97 that is provided between the first thick-walled portions 96 and is thinner than the first thick-walled portion 96. The flange base 95 has a second thick-walled portion 98 that is located radially inward of the first thick-walled portion 96 and is thicker than the first thick-walled portion 96.

[0004] When attaching a brake rotor (not shown) to the flange portion 92, it is necessary to temporarily fasten the brake rotor with a bolt. For this reason, tapped holes 99 for fixing the temporary fastening bolts are formed in the flange portion 92. The tapped holes 99 are formed in raised portions 94 provided on the flange portion 92 because it is necessary to ensure a fitting length with the bolts. By forming the tapped holes 99 in the raised portions 94, a wall-like thick portion is ensured around the tapped holes 99. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-15398 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional wheel bearing device shown in Fig. 9, the flange portion 92 has a thick portion (protruding portion 94) only around the tapped hole 99, so when the brake rotor is temporarily fixed, the weight of the brake rotor may distort the tapped hole 99. Furthermore, if the flange portion 92 is provided with the protruding portion 94 to ensure the strength of the tapped hole 99, the weight of the inner shaft 90 increases, and there is a concern that the weight balance of the flange portion 92 in the circumferential direction may deteriorate.

[0007] An object of the present disclosure is to ensure the strength of a tapped hole while simultaneously suppressing an increase in the weight of an inner shaft and ensuring circumferential weight balance in a wheel bearing device. [Means for solving the problem]

[0008] The wheel bearing device disclosed herein comprises an outer member, an inner member having a wheel mounting flange on one axial side with a plurality of bolt holes for fixing to the wheel and tapped holes for fixing a brake rotor, and a plurality of rolling elements arranged between the outer member and the inner member, wherein the wheel mounting flange has thin-walled portions formed in a region between circumferentially adjacent bolt holes, a first region having a through hole passing through in the axial direction and not having the tapped hole, and a second region having the tapped hole, a first thick-walled portion including a portion where the region around the bolt hole is raised from the thin-walled portion to the other axial side, and a second thick-walled portion where the region around the tapped hole is raised from the thin-walled portion of the second region to the other axial side. Effect of the Invention

[0009] According to the wheel support bearing device of the present disclosure, in the wheel support bearing device, it is possible to ensure the strength of the tapped hole while simultaneously suppressing an increase in the weight of the inner member and ensuring the circumferential weight balance. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an example of a wheel bearing device. [Diagram 2] FIG. 2 is a perspective view of an inner shaft according to the first embodiment. [Diagram 3] FIG. 2 is a view of an inner shaft according to the first embodiment as viewed from the axial direction. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 11 is a perspective view of an inner shaft according to a second embodiment. [Figure 6] FIG. 11 is a view of an inner shaft according to a second embodiment as viewed from the axial direction. [Figure 7] FIG. 11 is a perspective view of an inner shaft according to a third embodiment. [Figure 8] FIG. 11 is a view of an inner shaft according to a third embodiment, as viewed from the axial direction. [Figure 9] FIG. 1 is a perspective view of a conventional inner shaft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Summary of the embodiment of the present disclosure> Below, an overview of the embodiments of the present disclosure will be listed and described.

[0012] (1) A wheel bearing device disclosed herein comprises an outer member, an inner member having a wheel mounting flange on one axial side with a plurality of bolt holes for fixing to a wheel and tapped holes for fixing a brake rotor, and a plurality of rolling elements arranged between the outer member and the inner member, wherein the wheel mounting flange has thin-walled portions formed in a first region between circumferentially adjacent bolt holes, the first region having a through hole passing through in the axial direction and not having the tapped hole, and a second region having the tapped hole, a first thick-walled portion including a portion where the region around the bolt hole is raised from the thin-walled portion to the other axial side, and a second thick-walled portion where the region around the tapped hole is raised from the thin-walled portion of the second region to the other axial side.

[0013] In the wheel bearing device having such a configuration, the provision of the second thick-walled portion ensures the strength of the tapped hole, and the provision of the through hole prevents an increase in weight of the wheel mounting flange and ensures a circumferential weight balance of the wheel mounting flange. Thus, with the above configuration, in the wheel bearing device, it is possible to ensure the strength of the tapped hole while simultaneously preventing an increase in weight of the inner member and ensuring a circumferential weight balance.

[0014] (2) In the wheel bearing device of the present disclosure, the first thick-walled portion preferably has an annular base portion located radially inward, and a protruding portion that is a portion in which the area around the bolt hole is raised from the thin-walled portion to the other axial side and protrudes radially outward from the base portion, and the second thick-walled portion is connected to the protruding portions on both circumferential sides. This configuration can increase the strength of the second thick-walled portion. This can prevent the weight of the brake rotor from distorting the tapped hole when the brake rotor is temporarily attached to the wheel mounting flange.

[0015] (3) In the wheel bearing device of the present disclosure, the thin-walled portion of the first region includes a first thin-walled portion in which the first through hole is formed and a second thin-walled portion in which the second through hole having a diameter smaller than that of the first through hole is formed. With this configuration, it is possible to ensure a weight balance in the circumferential direction of the wheel mounting flange.

[0016] (4) The wheel bearing device of the present disclosure preferably has two tapped holes, with the first thin-walled portion being disposed on the side where the tapped holes are spaced closer to each other in the circumferential direction, and the second thin-walled portion being disposed on the side where the tapped holes are spaced closer to each other in the circumferential direction. With this configuration, it is possible to ensure a circumferential weight balance in a wheel mounting flange having two tapped holes.

[0017] (5) The wheel bearing device of the present disclosure preferably has one tapped hole, and the second thin portion is disposed circumferentially farther away from the second thick portion than the first thin portion is. With this configuration, a wheel mounting flange having one tapped hole can ensure circumferential weight balance.

[0018] (6) In the wheel bearing device of the present disclosure, the second thick-walled portion has an axial dimension smaller than the axial dimension of the first thick-walled portion. With this configuration, an increase in weight of the wheel mounting flange can be suppressed.

[0019] (7) In the wheel bearing device of the present disclosure, the second thick portion is preferably connected to the base portion at a radially inner side thereof. With this configuration, the strength of the second thick portion can be further increased.

[0020] <Details of the embodiment of the present disclosure> Hereinafter, an embodiment of the present disclosure will be described.

[0021] [Bearing device] FIG. 1 is a cross-sectional view showing an example of a wheel bearing device. The wheel bearing device 10 (hereinafter referred to as "bearing device 10") shown in FIG. 1 is a so-called hub unit, which is attached to a suspension device (knuckle) provided on the body of an automobile and supports a wheel so that the wheel can rotate. A brake disc is attached to the bearing device 10 in addition to the wheel, although not shown. The bearing device 10 includes an inner member 11, a cylindrical outer ring (outer member) 12, balls 13 as rolling elements, a retainer 14, a first sealing device 15 provided on one axial side, and a second sealing device 16 provided on the other axial side. In the bearing device 10, the axial direction is the direction along the center line C0 of the bearing device 10, and the direction parallel to the center line C0 is also referred to as the axial direction. The radial direction is the direction perpendicular to the center line C0, and the circumferential direction is the direction of rotation about the center line C0.

[0022] The outer ring 12 has a cylindrical outer ring body 21 and a fixing flange 22 extending radially outward from the outer ring body 21. Outer raceway surfaces 12a, 12b are formed on the inner circumferential side of the outer ring body 21. The outer ring 12 is attached to a knuckle (not shown), which is a vehicle body member, by the flange 22, and thus the bearing device 10 including the outer ring 12 is fixed to the vehicle body. With the bearing device 10 fixed to the vehicle body, a flange 27 for wheel attachment, which will be described later, of the inner member 11 is on the outer side of the vehicle. In other words, one axial side on which the flange 27 is provided is the vehicle outer side, and the opposite other axial side is the vehicle inner side.

[0023] The inner member 11 has an inner shaft (hub shaft) 23 and an inner ring 24 attached to the other axial side of the inner shaft 23. FIGS. 1 to 4 show the inner shaft 23 according to a first embodiment. In the following description, the inner shaft 23 according to the first embodiment will be referred to as a first inner shaft 23A. Note that in this description, when simply referring to the "inner shaft 23," a configuration common to the first inner shaft 23A and the second inner shaft 23B (see FIGS. 5 and 6) and third inner shaft 23C (see FIGS. 7 and 8), which will be described later, is described.

[0024] The inner shaft 23 has a shaft-shaped main body 26 provided radially inward of the outer ring 12, and a flange portion (wheel mounting flange) 27 provided on one axial side of the main body 26. A plurality of bolt holes 28 for mounting a wheel are formed in the flange portion 27. The inner shaft 23 further has a crimped portion 25 for preventing the inner ring 24 from falling off to the other axial side. The center line of the inner shaft 23 coincides with the center line C0 of the bearing device 10. The flange portion 27 is provided extending radially outward from one axial side of the main body 26. A wheel and a brake rotor (not shown) are attached to a surface (flange surface 55) on one axial side of the flange portion 27. The crimped portion 25 is formed by expanding the diameter of a cylindrical portion 25a by plastic deformation. In FIG. 1, the cylindrical portion 25a before plastic deformation is indicated by a two-dot chain line.

[0025] The outer peripheral surface of the main body portion 26 has a stepped shape. That is, the main body portion 26 has a first shaft portion 29 on which the inner raceway surface 11a is formed, and a second shaft portion 30 whose outer peripheral surface has a smaller diameter than that of the first shaft portion 29. With the inner ring 24 fitted onto the second shaft portion 30, the cylindrical portion 25a is plastically deformed to expand in diameter to form the crimped portion 25. As a result, the inner ring 24 is sandwiched between the first shaft portion 29 and the crimped portion 25.

[0026] The inner ring 24 is an annular member, and is fitted and fixed to the second shaft portion 30. A first inner raceway surface 11a is formed on the outer peripheral surface of the first shaft portion 29, and a second inner raceway surface 11b is formed on the outer peripheral surface of the inner ring 24. A plurality of balls 13 are arranged between the outer raceway surface 12a and the inner raceway surface 11a on one axial side. A plurality of balls 13 are arranged between the outer raceway surface 12b and the inner raceway surface 11b on the other axial side.

[0027] The components of the bearing device 10, that is, the inner shaft 23, the inner ring 24, the outer ring 12, and the balls 13, are made of steel (carbon steel, bearing steel). The cage 14 may be made of steel or resin.

[0028] Between the inner member 11 and the outer ring 12, an annular space K in which balls 13 are provided is formed. A first sealing device 15 is provided on one axial side of the annular space K, and a second sealing device 16 is provided on the other axial side of the annular space K. The sealing devices 15, 16 prevent foreign matter from entering the annular space K. The first sealing device 15 has an annular seal member 31 attached to the outer ring 12, and an annular slinger 32 attached along a base portion 35 (described later) of the inner shaft 23. A part of the seal member 31 (lip portion 31a) contacts the slinger 32. As a result, the first sealing device 15 can prevent foreign matter from entering the annular space K from between the flange portion 27 and the outer ring 12.

[0029] (Regarding the inner shaft according to the first embodiment) FIG. 2 is a perspective view of the inner shaft 23 (first inner shaft 23A) according to the first embodiment. FIG. 3 is a view of the first inner shaft 23A as viewed from the axial direction. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3. As shown in FIGS. 2 to 4, in the first inner shaft 23A, the disk-shaped flange portion 27 has a first thick portion 33 provided on the radially inner side and a plurality of thin portions 34 provided on the radially outer side. The first thick portion 33 has a base portion 35 that is circular (annular in this embodiment) in a cross section perpendicular to the center line C0, and a plurality of protruding portions 36 that protrude radially outward from the base portion 35. The base portion 35 is a portion located on the radially inner side of the first thick portion 33. The protruding portions 36 are provided at equal intervals in the circumferential direction, and have bolt holes 28 formed therein. In other words, the protruding portions 36 are portions in which the area around the bolt holes 28 is raised from the thin portions 34 to the other axial side. The first thick-walled portion 33 includes a protruding portion 36 that protrudes from the thin-walled portion 34 toward the other axial side in the region surrounding the bolt hole 28. The protruding portion 36 is thinner than the base portion 35.

[0030] The thin portion 34 is provided radially outward of the base 35, between the protruding portions 36, 36 adjacent to each other in the circumferential direction. The thin portion 34 is thinner than the first thick portion 33. In other words, the axial dimension D3 of the thin portion 34 is smaller than the axial dimension D1 of the first thick portion 33 (protruding portion 36) (see FIG. 4).

[0031] Since the bolt holes 28 are provided in the protruding portions 36, the number of the protruding portions 36 is the same as the number of the bolt holes 28 ("5" in the first inner shaft 23A). Moreover, since the thin-walled portions 34 are provided between the protruding portions 36, 36 adjacent to each other in the circumferential direction, the number of the thin-walled portions 34 is the same as the number of the protruding portions 36 ("5" in the first inner shaft 23A).

[0032] The flange portion 27 further has a second thick portion 37. The second thick portion 37 in the first inner shaft 23A is provided in two of the five thin portions 34. That is, the flange portion 27 of the present embodiment has a plurality of second thick portions 37. The second thick portions 37 are thinner than the first thick portion 33 and thicker than the thin portion 34. That is, the axial dimension D2 of the second thick portion 37 is smaller than the axial dimension D1 of the first thick portion 33 and larger than the axial dimension D3 of the thin portion 34 (D1>D2>D3, see FIG. 4).

[0033] The flange portion 27 further has a tap hole 38 formed in the second thick portion 37. The second thick portion 37 is a portion formed by raising the area around the tap hole 38 from the third thin portion 34C described later toward the other axial side. The tap hole 38 is used for temporarily fixing the brake rotor, not shown. The flange portion 27 of the first inner shaft 23A is provided with two tap holes 38. In other words, the first inner shaft 23A is provided with two second thick portions 37 in order to provide the two tap holes 38 in the flange portion 27. By providing the second thick portions 37 in the first inner shaft 23A, it is possible to ensure the strength of the tap holes 38.

[0034] The second thick-walled portion 37 is connected on both circumferential sides to the protruding portion 36 of the first thick-walled portion 33. Such a second thick-walled portion 37 has increased rigidity compared to a case in which both circumferential sides are not connected to the protruding portion 36. With the first inner shaft 23A configured in this manner, when a brake rotor (not shown) is temporarily fixed to the flange portion, rigidity sufficient to prevent distortion of the tapped hole 38 due to the weight of the brake rotor can be ensured.

[0035] The second thick-walled portion 37 is further connected at its radially inner side to the base 35 of the first thick-walled portion 33. Such a second thick-walled portion 37 has increased rigidity compared to a case in which the radially inner side is not connected to the base 35. With the first inner shaft 23A configured in this manner, when a brake rotor (not shown) is temporarily fixed to the flange portion, it is possible to reliably prevent the tapped hole 38 from being distorted by the weight of the brake rotor.

[0036] The flange portion 27 further includes a plurality of through holes 40. The through holes 40 are holes provided to reduce the weight of the flange portion 27 and balance the weight in the circumferential direction. The through holes 40 include a first through hole 41 and a second through hole 42. In this embodiment, the first through hole 41 and the second through hole 42 are provided in the thin-walled portion 34 (the remaining three portions) where the second thick-walled portion 37 is not provided, among the five thin-walled portions 34. In the first inner shaft 23A, one first through hole 41 and two second through holes 42 are formed in the flange portion 27. The second through hole 42 has a smaller diameter than the first through hole 41. In the first inner shaft 23A, the first through hole 41 is formed by enlarging it to a position where the base portion 35 of the first thick-walled portion 33 is cut out, and a necessary diameter for the first through hole 41 is ensured. In the following description, the thin-walled portion 34 in which the first through hole 41 is formed is referred to as the first thin-walled portion 34A, the thin-walled portion 34 in which the second through hole 42 is formed is referred to as the second thin-walled portion 34B, and the thin-walled portion 34 in which the second thick-walled portion 37 is formed is referred to as the third thin-walled portion 34C. The first thin-walled portion 34A, the second thin-walled portion 34B, and the third thin-walled portion 34C are all thin-walled portions 34 formed in the regions between the bolt holes 28, 28 adjacent to each other in the circumferential direction. The first thin-walled portion 34A and the second thin-walled portion 34B are thin-walled portions 34 formed in the regions (first regions) that do not have the tapped holes 38 among the regions between the bolt holes 28, 28 adjacent to each other in the circumferential direction. The third thin-walled portion 34C is the thin-walled portion 34 formed in the regions (second regions) that have the tapped holes 38 among the regions between the bolt holes 28, 28 adjacent to each other in the circumferential direction.

[0037] In the first inner shaft 23A, the second thick portions 37 and the tapped holes 38 are not formed at equal intervals in the circumferential direction in the flange portion 27. Therefore, the flange portion 27 does not have a circumferential weight balance when only the portion of the second thick portion 37 and the tapped holes 38 (the third thin portion 34C) is viewed. In the first inner shaft 23A, the flange portion 27 is provided with a plurality of thin portions 34 (specifically, the first thin portion 34A and the second thin portion 34B) in which the through holes 40 are formed, so that the center of gravity of the flange portion 27 is positioned on the center line C0, thereby ensuring the circumferential weight balance of the flange portion 27. Note that in the first inner shaft 23A, the flange portion 27 is provided with a plurality of types of through holes 40 (the first through hole 41 and the second through hole 42) having different diameters, but in the bearing device of the present disclosure, all of the plurality of through holes may have the same diameter. From the viewpoint of ensuring the rigidity of the flange portion 27, it is preferable to ensure a radial thickness of 4 mm or more on the radially outer side of the through hole 40.

[0038] In the first inner shaft 23A, one thin-walled portion 34 on the side where the circumferential distance between the two tapped holes 38 is smaller is a first thin-walled portion 34A in which a first through hole 41 is formed, and two thin-walled portions 34 on the side where the circumferential distance between the tapped holes 38 is larger is a second thin-walled portion 34B in which a second through hole 42 is formed. In the first inner shaft 23A, the first thin-walled portion 34A and the second thin-walled portion 34B are arranged in this manner, thereby ensuring a circumferential weight balance of the flange portion 27. In other words, in the first inner shaft 23A, when the second thick-walled portion 37 and the tapped holes 38 (third thin-walled portion 34C) are unequally spaced in the circumferential direction, the through holes 40 (first through hole 41 and second through hole 42) are formed unequally spaced in the circumferential direction, thereby ensuring a circumferential weight balance of the flange portion 27. In other words, by providing the first inner shaft 23A with the first thin portion 34A and the second thin portion 34B, it is possible to suppress an increase in the weight of the flange portion 27 and ensure the weight balance of the flange portion 27 in the circumferential direction.

[0039] (Second embodiment of the inner shaft) Fig. 5 is a perspective view of the inner shaft 23 according to the second embodiment. Fig. 6 is a view of the inner shaft 23 according to the second embodiment as viewed from the axial direction. In the bearing device 10, the inner shaft 23 according to the second embodiment shown in Figs. 5 and 6 (hereinafter referred to as the second inner shaft 23B) may be used as the inner shaft 23. In the second inner shaft 23B shown in Figs. 5 and 6, the same reference numerals are used for parts having a common configuration with the first inner shaft 23A, and explanations of the parts having the same reference numerals will be omitted unless otherwise specified.

[0040] As shown in FIG. 5 and FIG. 6, the second inner shaft 23B has five protruding portions 36 and thin-walled portions 34, which is the same number as the number of bolt holes 28 ("5" in the second inner shaft 23B), and in this respect, the second inner shaft 23B has a configuration common to the first inner shaft 23A. The second inner shaft 23B has one second thick-walled portion 37, which is the same number as the number of tapped holes 38 ("1" in the second inner shaft 23B), and in this respect, the second inner shaft 23B has a configuration different from the first inner shaft 23A. The third thin-walled portion 34C of the second inner shaft 23B is one of the five thin-walled portions 34. In the second inner shaft 23B, the second thick-walled portion 37 is formed in only one place in the flange portion 27. In other words, in the second inner shaft 23B, one second thick-walled portion 37 is provided in order to provide one tapped hole 38 in the flange portion 27. In the second inner shaft 23B, the strength of the tapped hole 38 is ensured by providing the second thick-walled portion 37.

[0041] In the second inner shaft 23B, the first thin-walled portion 34A and the second thin-walled portion 34B are provided in the remaining four thin-walled portions 34 other than the third thin-walled portion 34C among the five thin-walled portions 34. In the second inner shaft 23B, a total of four through holes 40 including two first through holes 41 and two second through holes 42 are formed in the flange portion 27.

[0042] In the second inner shaft 23B, the two thin-walled portions 34 that are close to the tap hole 38 are defined as first thin-walled portions 34A, and the two thin-walled portions 34 that are close to the tap hole 38 are defined as second thin-walled portions 34B. In the second inner shaft 23B, the first thin-walled portions 34A and the second thin-walled portions 34B are disposed in this manner, thereby ensuring a circumferential weight balance of the flange portion 27. In other words, in the second inner shaft 23B, by providing the first thin-walled portions 34A and the second thin-walled portions 34B, an increase in the weight of the flange portion 27 is suppressed and a circumferential weight balance of the flange portion 27 is ensured.

[0043] (Regarding the third embodiment of the inner shaft) Fig. 7 is a perspective view of the inner shaft 23 according to the third embodiment. Fig. 8 is a view of the inner shaft 23 according to the third embodiment as viewed from the axial direction. In the bearing device 10, the inner shaft 23 according to the third embodiment shown in Figs. 7 and 8 (hereinafter referred to as the third inner shaft 23C) may be used as the inner shaft 23. In the third inner shaft 23C shown in Figs. 7 and 8, the same reference numerals are used for parts having a common configuration with the first inner shaft 23A and the second inner shaft 23B, and explanations of the parts having the same reference numerals will be omitted unless otherwise specified.

[0044] As shown in Figs. 7 and 8, the third inner shaft 23C has four protrusions 36 and thin-walled portions 34, which is the same number as the number of bolt holes 28 ("4" in the third inner shaft 23C), and in this respect, the third inner shaft 23C has one second thick-walled portion 37, which is the same number as the number of tapped holes 38 ("1" in the third inner shaft 23C), and in this respect, the third inner shaft 23C has a different configuration from the first inner shaft 23A and a common configuration with the second inner shaft 23B. The third thick-walled portion 34C of the third inner shaft 23C is one of the four thin-walled portions 34. In the third inner shaft 23C, the second thick-walled portion 37 is formed in only one location in the flange portion 27. In other words, in the third inner shaft 23C, one second thick-walled portion 37 is provided in order to provide one tapped hole 38 in the flange portion 27. In the third inner shaft 23C, the second thick-walled portion 37 is provided to ensure the strength of the tapped hole .

[0045] In the third inner shaft 23C, the first thin-walled portion 34A and the second thin-walled portion 34B are provided in the remaining three thin-walled portions 34 other than the third thin-walled portion 34C among the four thin-walled portions 34. In the third inner shaft 23C, a total of three through holes 40 including two first through holes 41 and one second through hole 42 are formed in the flange portion 27.

[0046] In the third inner shaft 23C, the two thin-walled portions 34 that are close to the tap hole 38 are designated as first thin-walled portions 34A, and the one thin-walled portion 34 that is close to the tap hole 38 is designated as second thin-walled portion 34B. In the third inner shaft 23C, the first thin-walled portion 34A and the second thin-walled portion 34B are arranged in this manner, thereby ensuring a circumferential weight balance of the flange portion 27. In other words, in the third inner shaft 23C, by providing the first thin-walled portion 34A and the second thin-walled portion 34B, an increase in the weight of the flange portion 27 is suppressed and a circumferential weight balance of the flange portion 27 is ensured.

[0047] In the inner shaft 23 having four bolt holes 28 like the third inner shaft 23C, it is possible to provide two second thick portions 37 and tap holes 38 in the thin portions 34 that are circumferentially shifted in phase by 180 degrees. In this case, by equally distributing the second thick portions 37 in the circumferential direction of the flange portion 27, it is possible to ensure a circumferential weight balance of the flange portion 27. Also in this case, through holes 40 may be provided in the remaining two thin portions 34 that are not provided with the second thick portions 37 and tap holes 38, thereby reducing the weight of the flange portion 27.

[0048] (Effects of the embodiment) The bearing device 10 in the embodiment described above includes an outer ring 12, an inner shaft 23 having a flange portion 27 on one axial side provided with a plurality of bolt holes 28 for fixing to a wheel and tapped holes 38 for fixing a brake rotor, and a plurality of balls 13 arranged between the outer ring 12 and the inner shaft 23. The flange portion 27 has a thin-walled portion 34 formed in a first region between circumferentially adjacent bolt holes 28, the first region having a through hole 40 penetrating in the axial direction and no tapped hole 38, and a second region having the tapped hole 38, a first thick-walled portion 33 including a portion where the region around the bolt hole 28 is raised from the thin-walled portion 34 to the other axial side, and a second thick-walled portion 37 where the region around the tapped hole 38 is raised from the thin-walled portion 34 of the second region to the other axial side.

[0049] In the bearing device 10 configured as described above, the provision of the second thick-walled portion 37 ensures the strength of the tapped hole 38, and the provision of the through hole 40 prevents an increase in weight of the flange portion 27 and ensures a circumferential weight balance of the flange portion 27. Thus, with this configuration, in the bearing device 10, it is possible to ensure the strength of the tapped hole 38 while simultaneously preventing an increase in weight of the flange portion 27 and ensuring a circumferential weight balance.

[0050] In the bearing device 10 according to the embodiment described above, the first thick portion 33 has an annular base portion 35 located radially inward, and protruding portions 36 that are portions of the area around the bolt holes 28 raised from the thin portion 34 to the other axial side and that protrude radially outward from the base portion 35, and the second thick portion 37 is connected to the protruding portions 36 of the first thick portion 33 on both circumferential sides. This configuration can increase the strength of the second thick portion 37. This can prevent the tapped hole 38 from being distorted by the weight of the brake rotor when the brake rotor is temporarily fixed to the flange portion 27.

[0051] Moreover, the bearing device 10 in the embodiment described above has, as the thin-walled portion 34 of the first region, a first thin-walled portion 34A in which a first through hole 41 is formed, and a second thin-walled portion 34B in which a second through hole 42 having a diameter smaller than that of the first through hole 41 is formed. With this configuration, it is possible to ensure the weight balance in the circumferential direction of the flange portion 27.

[0052] Moreover, the first inner shaft 23A of the bearing device 10 in the embodiment described above has two tapped holes 38, with the first thin-walled portion 34A disposed on the side where the distance between the tapped holes 38 in the circumferential direction is smaller, and the second thin-walled portion 34B disposed on the side where the distance between the tapped holes 38 in the circumferential direction is larger. With this configuration, it is possible to ensure circumferential weight balance in the flange portion 27 having the tapped holes 38 in two locations.

[0053] Moreover, the second inner shaft 23B and the third inner shaft 23C of the bearing device 10 in the embodiment described above have one tapped hole 38, and the second thin portion 34B is disposed circumferentially farther from the second thick portion 37 than the first thin portion 34A. With this configuration, it is possible to ensure circumferential weight balance in the flange portion 27 having one tapped hole 38.

[0054] In the bearing device 10 according to the embodiment described above, the axial dimension D2 of the second thick portion 37 is smaller than the axial dimension D1 of the first thick portion 33. With this configuration, an increase in the weight of the flange portion 27 can be suppressed.

[0055] In the bearing device 10 according to the embodiment described above, the second thick portion 37 is connected to the base portion 35 of the first thick portion 33 on the radially inner side. With this configuration, the strength of the second thick portion 37 can be further increased.

[0056] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is not limited to the above-described embodiments, and includes all modifications within the scope of equivalents to the configurations described in the claims. For example, although the rolling elements are described as balls 13, the rolling elements may be rollers (tapered rollers). [Explanation of symbols]

[0057] 10: Wheel bearing device 11: Inner member 12: Outer ring (outer part) 13: Ball (rolling element) 23: Inner shaft 27: Flange section (wheel mounting flange) 28:Bolt hole 33:First thick part 34: Thin section 34A: First thin section 34B: Second thin section 35: Base (first thick part) 36: Protruding part (first thick part) 37:Second thick part 38: Tap hole 40:Through hole 41:First through hole 42:Second through hole D1: Axial dimension of the protrusion (first thick part) D2: Axial dimension of the second thick-walled section

Claims

1. An outer member; an inner member having a wheel mounting flange on one axial side, the wheel mounting flange having a plurality of bolt holes spaced apart in the circumferential direction for fastening to the wheel and a tapped hole for fastening the brake rotor; a plurality of rolling elements disposed between the outer member and the inner member; having The wheel mounting flange is a first region between the bolt holes adjacent in the circumferential direction and not including the tapped hole; a second region between the bolt holes adjacent in the circumferential direction and having the tapped hole; The wheel mounting flange is a thin-walled portion formed in the first region and the second region; a first thick-walled portion including a portion in which a region around the bolt hole is raised from the thin-walled portion to the other axial direction side; a second thick-walled portion in which a region around the tap hole is raised from the thin-walled portion of the second region to the other axial side, The first region is provided with a through hole that penetrates in the axial direction and is used to balance the weight in the circumferential direction, The wheel bearing device, wherein the through hole is not provided in the second region.

2. the first thick-walled portion has an annular base portion located radially inward, and a protruding portion that is a portion in which a region around the bolt hole is raised from the thin-walled portion to the other axial side and protrudes radially outward from the base portion, The wheel bearing device according to claim 1 , wherein the second thick portion is connected to the protruding portion on both circumferential sides.

3. 3. The wheel bearing device according to claim 1, wherein the thin-walled portion of the first region includes a first thin-walled portion in which a first through hole is formed, and a second thin-walled portion in which a second through hole having a diameter smaller than that of the first through hole is formed.

4. The tap hole is provided at two locations. the first thin-walled portion is disposed on a side where an interval between the tapped holes in a circumferential direction is smaller, The wheel bearing device according to claim 3 , wherein the second thin-walled portion is disposed on a side where an interval between the tapped holes in the circumferential direction is larger.

5. The tap hole is provided at one location. The wheel bearing device according to claim 3 , wherein the second thin portion is disposed farther circumferentially from the second thick portion than the first thin portion is.

6. The wheel bearing device according to claim 1 , wherein an axial dimension of the second thick-walled portion is smaller than an axial dimension of the first thick-walled portion.

7. The wheel bearing device according to claim 2 , wherein the second thick-walled portion is connected to the base portion on a radially inner side.

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