Bearing device for wheel

Abstract

The invention provides a bearing device for a wheel, which can improve the sliding torque resistance of a hub bolt relative to a bolt hole and suppress the strain of a hub flange caused by the pressing of the hub bolt. A wheel bearing device (1) is provided with: an outer ring (2) having double rows of outer raceway surfaces (23, 24) on the inner periphery thereof; an inner member comprising a hub ring (3) having, on the outer periphery thereof, one inner raceway surface (33) facing the outer raceway surface and a hub flange (32) to which a wheel is attached, and an inner ring (4) connected to the hub ring and having, on the outer periphery thereof, the other inner raceway surface (41) facing the outer raceway surface; an inner-side ball row (5) and an outer-side ball row (6) which are accommodated between the raceway surfaces of the outer ring, the hub ring and the inner ring in a rolling manner; and a hub bolt (36) press-fitted into a bolt hole (35) formed in the hub flange, the difference between the surface hardness of the bolt hole in the hub flange and the surface hardness of the hub bolt being 42 HRC to 50 HRC.

Description

Technical Field

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

[0002] Conventionally, a wheel bearing device is known for supporting a wheel rotatably in a suspension device of a motor vehicle or the like. In the wheel bearing device, a hub ring as an inner member has a hub flange extending toward the outer diameter side, and hub bolts for fastening the hub ring to the wheel or the like are pressed into bolt holes formed in the hub flange.

[0003] When the hub bolts are pressed into the bolt holes of the hub flange, if the interference of the hub bolts with respect to the bolt holes is increased in order to fully ensure the sliding torque resistance of the hub bolts with respect to the bolt holes, strain will be applied to the hub flange, causing the flange surface of the hub flange to vibrate and tilt. If the flange surface vibrates and tilts, it is possible that the brake disc fixed to the flange surface will vibrate, causing brake judder and noise.

[0004] In particular, in recent years, further weight reduction of wheel bearing devices has been sought in order to achieve lower fuel consumption of vehicles. Due to the thinning of the hub flange accompanying the weight reduction of the wheel bearing device, the strain generated in the hub flange tends to increase.

[0005] Regarding the suppression of the strain generated in the hub flange due to the press-fitting of the hub bolts, for example, the following processing is performed: when the thermal influence of the quench-hardened layer formed on the hub ring affects the portion of the hub flange where the bolt holes are formed, the strain generated in the hub flange becomes larger, so the structure is configured so that the thermal influence of the quench-hardened layer formed on the hub ring does not affect the portion of the hub flange where the bolt holes are formed (see patent document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2000-219006 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In addition, in order to suppress the strain of the hub flange caused by press-fitting the hub bolts into the bolt holes, it is considered to reduce the interference of the hub bolts with respect to the bolt holes. However, when the interference of the hub bolts with respect to the bolt holes is reduced, it may not be possible to fully ensure the anti-sliding torque of the hub bolts with respect to the bolt holes.

[0011] The present invention has been made in view of the above circumstances, and provides a wheel bearing device capable of simultaneously achieving an improvement in the sliding torque resistance of the hub bolt with respect to the bolt hole and a suppression of the strain of the hub flange caused by the press-fitting of the hub bolt.

[0012] Solutions to Solve Problems

[0013] That is, the wheel bearing device comprises: an outer member having a double row of outer raceway surfaces on the inner circumference; an inner member composed of a hub ring and a raceway surface forming member, the hub ring having an inner raceway surface on the outer circumference that is opposite to the outer raceway surface and a hub flange for mounting the wheel, the raceway surface forming member being connected to the hub ring, and the raceway surface forming member having an inner raceway surface on the outer circumference that is opposite to the outer raceway surface; double rows of rolling elements that are freely accommodated between the two raceway surfaces of the outer member and the inner member; and hub bolts that are pressed into bolt holes formed in the hub flange, wherein the difference between the surface hardness of the bolt holes in the hub flange and the surface hardness of the hub bolts is 42HRC to 50HRC.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to improve the sliding torque resistance of the hub bolt with respect to the bolt hole and suppress deformation occurring in the hub flange. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side sectional view showing the wheel bearing device.

[0017] Figure 2 It is a side cross-sectional view showing the hub bolts and the bolt holes of the hub flange.

[0018] Figure 3 It is an axial cross-sectional view showing the knurled portion of the hub bolt.

[0019] Figure 4 It is an axial cross-sectional view showing the convex portion of the knurled portion in the hub bolt and the concave portion of the bolt hole in the hub flange.

[0020] Figure 5 It is a side cross-sectional view showing a state where a hub bolt is press-fitted into a bolt hole of a hub flange.

[0021] Figure 6 1 is a side sectional view showing a second embodiment of a hub flange.

[0022] Figure 7 1 is a side sectional view showing a third embodiment of a hub flange.

[0023] Figure 81 is a side sectional view showing a fourth embodiment of a hub flange.

[0024] Fig. 9 1 is a side sectional view showing a fifth embodiment of a hub flange.

[0025] Fig.10 It is a side sectional view showing a wheel bearing device of a fourth generation structure.

[0026] Description of Reference Numerals

[0027] 1Wheel bearing device

[0028] 2 Outer ring

[0029] 3 wheel hub

[0030] 4Inner circle

[0031] 5 internal side ball rows

[0032] 6 external side ball rows

[0033] 23 (Inner side) Outer track surface

[0034] 24 (outer side) outer track surface

[0035] 32, 32A, 32B, 32C, 32D wheel hub flange

[0036] 33 Inner track surface

[0037] 35, 35A, 35B, 35C, 35D bolt holes

[0038] 36 wheel hub bolts

[0039] 36B Knurling

[0040] 41 Inner track surface

[0041] 321, 321A, 321B, 321C, 321D flange surface

[0042] 322, 322A, 322B, 322C, 322D side

[0043] 351 concavity

[0044] 361 convex part

[0045] 361a first inclined surface

[0046] 361b Second inclined surface

[0047] 3211, 3211A, 3211B, 3211C, 3211CD outer diameter side flange surface 3221, 3221B, 3221D outer diameter side surface

[0048] θ1 (angle formed by the first inclined surface and the second inclined surface), θ3, θ6 (angle of the outer diameter side flange surface with respect to the radial direction), θ4, θ7 (angle of the outer diameter side surface with respect to the radial direction). DETAILED DESCRIPTION

[0049] Hereinafter, embodiments for implementing the present invention will be described using the drawings.

[0050] [Wheel bearing device]

[0051] Figure 1 The wheel bearing device 1 shown is one embodiment of the wheel bearing device of the present invention, and rotatably supports a wheel in a suspension device of a vehicle such as an automobile.

[0052] In the following description, the axial direction refers to the direction along the rotation axis X of the wheel bearing device 1. In addition, the outer side refers to the wheel side of the wheel bearing device 1 when it is installed on the vehicle body on one axial side, and the inner side refers to the vehicle body side of the wheel bearing device 1 when it is installed on the vehicle body on the other axial side.

[0053] The wheel bearing device 1 has a structure called the third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, an inner side ball row 5 and an outer side ball row 6 as double rows of rolling rows, an outer side sealing member 9, and an inner side sealing member 10. The inner ring 4 is an example of a raceway surface forming member connected to the hub ring.

[0054] An inner opening 21 into which the inner sealing member 10 can be fitted is formed at the inner end of the outer ring 2. An outer opening 22 into which the outer sealing member 9 can be fitted is formed at the outer end of the outer ring 2.

[0055] The inner side sealing member 10 is fitted into the inner side opening 21, thereby sealing the inner side opening end of the annular space S formed by the outer ring 2 as the outer member and the hub ring 3 and the inner ring 4 as the inner member. The outer side sealing member 9 is fitted into the outer side opening 22, thereby sealing the outer side opening end of the annular space S.

[0056] The inner side sealing member 10 and the outer side sealing member 9 are sealing devices that seal the open end of the annular space S. In this way, by using the inner side sealing member 10 and the outer side sealing member 9 to seal the inner and outer open ends of the annular space S, foreign matter such as muddy water is prevented from infiltrating into the wheel bearing device 1.

[0057] An inner outer raceway surface 23 and an outer outer raceway surface 24 are formed on the inner circumferential surface of the outer ring 2. A vehicle body mounting flange 25 for mounting the outer ring 2 to a vehicle body side member is integrally formed on the outer circumferential surface of the outer ring 2. The vehicle body mounting flange 25 is provided with bolt holes 26 for screwing a fastening member (here, bolts) for fastening the vehicle body side member to the outer ring 2.

[0058] A small-diameter step portion 31 having a smaller diameter than the outer end portion is formed at the inner end portion of the outer peripheral surface of the hub ring 3. A hub flange 32 for mounting a wheel is integrally formed at the outer end portion of the hub ring 3. The hub flange 32 extends toward the outer diameter side at the outer end portion, which is one end portion of the hub ring 3 in the axial direction.

[0059] A plurality of bolt holes 35 are formed in the hub flange 32. The bolt holes 35 penetrate the hub flange 32 in the axial direction. Hub bolts 36 for fastening and connecting the hub wheel 3 to the wheel or the brake member are press-fitted into the bolt holes 35.

[0060] The hub flange 32 has a flange surface 321 facing the outside and a side surface 322 facing the inside. The flange surface 321 and the side surface 322 are surfaces extending in a direction perpendicular to the axial direction. The wheel or brake component is fastened to the flange surface 321 of the hub flange 32 by the hub bolts 36 and wheel nuts (not shown).

[0061] In the hub ring 3, a sliding contact surface 34 is formed on the base side of the hub flange 32 for the outer side sealing member 9 to slide in contact with. An inner track surface 33 on the outer side is provided on the outer peripheral surface of the hub ring 3 in a manner opposed to the outer track surface 24 on the outer side of the outer ring 2. That is, on the outer side of the inner member, the inner track surface 33 is formed by the hub ring 3. The inner track surface 33 is an example of an inner track surface on the side opposed to the outer track surface.

[0062] The inner ring 4 is provided on the small-diameter step portion 31 of the hub wheel 3. The inner ring 4 is fixed to the small-diameter step portion 31 of the hub wheel 3 by only press-fitting, or by press-fitting and caulking. Figure 1 This is an example in which caulking is performed, and a caulking portion 37 that is caulked to the inner end surface 42 of the inner ring 4 is formed at the inner end portion of the hub wheel 3 .

[0063] The inner ring 4 is fixed in the axial direction by the caulking portion 37. The caulking portion 37 is formed by plastically deforming the inner end of the small-diameter step portion 31 toward the outer diameter side. The inner ring 4 applies preload to the inner ball row 5 and the outer ball row 6 as rolling rows.

[0064] An inner raceway surface 41 is provided on the outer circumferential surface of the inner ring 4 so as to face the outer raceway surface 23 on the inner side of the outer ring 2. That is, the inner raceway surface 41 is formed on the inner side of the inner member by the inner ring 4. The inner raceway surface 41 is an example of the inner raceway surface on the other side facing the outer raceway surface.

[0065] The inner ball row 5 and the outer ball row 6 as rolling rows are formed by holding a plurality of balls 7 as rolling bodies by a retainer 8. The inner ball row 5 is freely rollably sandwiched between the inner raceway surface 41 of the inner ring 4 and the outer raceway surface 23 on the inner side of the outer ring 2. The outer ball row 6 is freely rollably sandwiched between the inner raceway surface 33 of the hub ring 3 and the outer raceway surface 24 on the outer side of the outer ring 2. That is, the inner ball row 5 and the outer ball row 6 are freely rollably accommodated between the two raceway surfaces of the outer member and the inner member.

[0066] In the wheel bearing device 1, a double row angular contact ball bearing is formed by the outer ring 2, the hub ring 3, the inner ring 4, the inner ball row 5, and the outer ball row 6. It should be noted that the wheel bearing device 1 may also be formed by a double row tapered roller bearing instead of the double row angular contact ball bearing.

[0067] [Wheel hub bolts and hub flange bolt holes]

[0068] like Figure 2 As shown, the hub bolt 36 includes a head 36A, a knurled portion 36B, and an external thread portion 36C. The head 36A is disposed at the inner end of the hub bolt 36 and is located inside the hub flange 32 when the hub bolt 36 is press-fitted into the bolt hole 35 .

[0069] The knurled portion 36B is a portion of the hub bolt 36 that is pressed into the bolt hole 35. The knurled portion 36B is formed with a plurality of convex portions 361 extending in the axial direction along the circumferential direction (see FIG. Figure 3 ) The knurled portion 36B is disposed adjacent to the outer side of the head portion 36A.

[0070] The external thread portion 36C is disposed adjacent to the outer side of the knurled portion 36B. By screwing a mounting nut on the external thread portion 36C of the hub bolt 36 press-fitted into the bolt hole 35, the hub wheel 3 and the wheel or the brake member can be fastened and connected.

[0071] The knurled portion 36B of the hub bolt 36 has an interference fit with the bolt hole 35 of the hub flange 32 , and is press-fitted into the bolt hole 35 from the inner side of the hub flange 32 .

[0072] By pressing the knurled portion 36B into the bolt hole 35, the convex portion 361 of the knurled portion 36B bites into the inner peripheral surface of the bolt hole 35 in the hub flange 32, and the inner peripheral surface of the bolt hole 35 plastically deforms along the shape of the convex portion 361. Thus, the hub bolt 36 is prevented from rotating relative to the bolt hole 35 in the circumferential direction.

[0073] In the wheel bearing device 1 , the difference between the surface hardness of the knurled portion 36B in the hub bolt 36 and the surface hardness of the inner peripheral surface in the bolt hole 35 of the hub flange 32 is 42 HRC to 50 HRC.

[0074] In this case, the surface hardness of the knurled portion 36B can be obtained by measuring the hardness of a portion having a depth of 0.05 mm to 0.1 mm from the outer peripheral surface 360 ​​of the knurled portion 36B including the convex portion 361 at a plurality of locations (see Figure 3 “×” mark in the figure).

[0075] Similarly, the surface hardness of the inner peripheral surface of the bolt hole 35 can be obtained by measuring the hardness of a portion having a depth of 0.05 mm to 0.1 mm from the inner peripheral surface of the bolt hole 35 at a plurality of locations.

[0076] In this way, by setting the difference between the surface hardness of the knurled portion 36B and the surface hardness of the inner circumferential surface in the bolt hole 35 to 42HRC~50HRC, the knurled portion 36B can easily bite into the inner circumferential surface of the bolt hole 35, thereby improving the close contact between the knurled portion 36B and the inner circumferential surface of the bolt hole 35.

[0077] This can improve the degree of suppression of the rotation of the hub bolt 36 relative to the bolt hole 35 in the circumferential direction, thereby improving the sliding torque resistance of the hub bolt 36 relative to the bolt hole 35 in the circumferential direction.

[0078] Furthermore, since the anti-slip torque of the hub bolt 36 with respect to the bolt hole 35 is improved, the required anti-slip torque can be ensured even if the interference of the knurled portion 36B with respect to the bolt hole 35 is reduced.

[0079] When the hub bolts 36 are press-fitted into the bolt holes 35 , strain is applied to the hub flange 32 to cause deformation. However, by reducing the interference of the knurled portion 36B with respect to the bolt holes 35 , deformation occurring in the hub flange 32 can be suppressed.

[0080] It should be noted that in this embodiment, the difference in surface hardness between the knurled portion 36B and the inner circumferential surface of the bolt hole 35 is set to a range of 42HRC to 50HRC. When the difference in surface hardness is less than 42HRC, it may not be possible to fully obtain the amount by which the knurled portion 36B bites into the bolt hole 35.

[0081] Furthermore, when the difference in surface hardness exceeds 50 HRC, when a force in the rotational direction is applied to the hub bolt 36 , the inner peripheral surface of the bolt hole 35 is easily deformed in the circumferential direction, and there is a possibility that the sliding torque resistance cannot be sufficiently ensured.

[0082] like Figure 3 As shown in FIG. 1 , the convex portion 361 of the knurled portion 36B is formed into a peak shape protruding from the outer peripheral surface 360 ​​of the knurled portion 36B toward the outer diameter side. The convex portion 361 has a first inclined surface 361a and a second inclined surface 361b that are inclined toward the side where the distance between each other in the circumferential direction decreases as it approaches the front end side of the convex portion 361, and the angle θ1 formed by the first inclined surface 361a and the second inclined surface 361b of the convex portion 361 is an acute angle. In the present embodiment, the angle θ1 is set in the range of 50° to 80°.

[0083] In this way, by setting the angle θ1 formed by the first inclined surface 361a and the second inclined surface 361b to an acute angle, the convex portion 361 of the knurled portion 36B can easily bite into the inner peripheral surface of the bolt hole 35, which can improve the close contact between the knurled portion 36B and the inner peripheral surface of the bolt hole 35.

[0084] This can improve the degree of suppression of the rotation of the hub bolt 36 relative to the bolt hole 35 in the circumferential direction, thereby improving the sliding torque resistance of the hub bolt 36 relative to the bolt hole 35 in the circumferential direction.

[0085] In addition, since the anti-slip torque of the hub bolt 36 relative to the bolt hole 35 is improved, the required anti-slip torque can be ensured even if the interference of the knurled portion 36B relative to the bolt hole 35 is reduced. By reducing the interference of the knurled portion 36B relative to the bolt hole 35, the deformation generated in the hub flange 32 can be suppressed.

[0086] like Figure 4 As shown, in the knurled portion 36B of the hub bolt 36, an external spline is formed by a plurality of convex portions 361. A plurality of concave portions 351 extending in the axial direction are formed on the inner peripheral surface of the bolt hole 35 in the hub flange 32 along the circumferential direction, and an internal spline is formed by the plurality of concave portions 351. The concave portion 351 of the bolt hole 35 and the convex portion 361 of the knurled portion 36B can be spline-fitted.

[0087] The concave portion 351 of the bolt hole 35 that can be spline-fitted with the convex portion 361 of the knurled portion 36B is formed to have a smaller diameter than the convex portion 361 and to have an interference n with the convex portion 361. Therefore, when the convex portion 361 and the concave portion 351 are fitted, the convex portion 361 is pressed into the concave portion 351.

[0088] like Figure 4 , Figure 5As shown in the figure, when the convex part 361 is pressed into the concave part 351, the convex part 361 bites into the concave part 351, and the shape of the convex part 361 is transferred to the inner peripheral surface of the concave part 351. In this case, while the inner peripheral surface of the concave part 351 is extremely finely cut by the convex part 361, and is accompanied by extremely fine plastic deformation and elastic deformation, the shape of the convex part 361 is transferred to the inner peripheral surface of the concave part 351.

[0089] When the convex portion 361 is pressed into the concave portion 351 and the convex portion 361 and the concave portion 351 are spline-fitted, the outer peripheral surface of the convex portion 361 and the inner peripheral surface of the concave portion 351 are in close contact with each other as a whole.

[0090] In this way, the convex portion 361 and the concave portion 351 are spline-fitted in a state of being in close contact as a whole in the axial direction, so that the sliding torque resistance of the hub bolt 36 with respect to the bolt hole 35 in the circumferential direction can be increased.

[0091] In addition, since the anti-slip torque of the hub bolt 36 relative to the bolt hole 35 is increased, the required anti-slip torque can be ensured even if the interference of the knurled portion 36B relative to the bolt hole 35 is reduced. By reducing the interference of the knurled portion 36B relative to the bolt hole 35, the deformation generated in the hub flange 32 can be suppressed.

[0092] [Second Embodiment of Hub Flange]

[0093] When the hub bolts 36 are pressed into the bolt holes 35 of the hub flange 32 from the inner side, the flange surface 321 of the hub flange 32 may be deformed and tilted toward the outer side. In particular, the outer diameter side flange surface 3211, which is a portion of the flange surface 321 located on the outer diameter side of the bolt holes 35, is prone to tilting toward the outer side as the hub bolts 36 are pressed into the bolt holes 35.

[0094] In the wheel bearing device 1, by Figure 6 By forming the hub flange 32 like the hub flange 32A shown in the figure, it is possible to suppress the flange surface 321A from falling outward when the hub bolts 36 are press-fitted into the bolt holes 35 .

[0095] The hub flange 32A has a flange surface 321A facing the outside and a side surface 322A facing the inside. The flange surface 321A has an outer diameter side flange surface 3211A which is a portion located on the outer diameter side of the bolt hole 35A.

[0096] like Figure 6As shown in (a), in the hub flange 32A in a state where the hub bolt 36 is not pressed into the bolt hole 35A, the outer diameter side flange surface 3211A is formed as an inclined surface that is inclined toward the inner side as it approaches the outer diameter side. The inclination angle of the outer diameter side flange surface 3211A relative to the radial direction is θ2. It should be noted that the radial direction is a direction orthogonal to the axial direction.

[0097] like Figure 6 As shown in (b), the outer diameter side flange surface 3211A is tilted toward the outside due to the hub bolt 36 being pressed into the bolt hole 35A. Therefore, by pre-forming the outer diameter side flange surface 3211A as an inclined surface inclined toward the inside, the outer diameter side flange surface 3211A after the hub bolt 36 is pressed into can be made to be a surface perpendicular to the axial direction compared to the outer diameter side flange surface 3211A before the hub bolt 36 is pressed into.

[0098] Thus, in the finished wheel bearing device 1 in which the hub bolt 36 is press-fitted into the bolt hole 35A, the runout and tilt of the flange surface 321A can be controlled within a predetermined range, thereby suppressing the occurrence of brake judder and noise.

[0099] In addition, by suppressing the generation of brake judder, the NVH performance of the vehicle can be improved. It should be noted that the N in NVH performance refers to noise, V refers to vibration, and H refers to harshness.

[0100] For example, the inclination angle θ2 of the outer flange surface 3211A can be set to 4'. However, the magnitude of the inclination angle θ2 can be arbitrarily set according to the amount of tilting of the outer flange surface 3211A toward the outside when the hub bolt 36 is press-fitted into the bolt hole 35A.

[0101] [Third Embodiment of Hub Flange]

[0102] When the hub bolt 36 is pressed into the bolt hole 35 of the hub flange 32 from the inner side, depending on the shape of the hub flange 32 and the hub bolt 36, sometimes in addition to the outer diameter side flange surface 3211 of the hub flange 32, the portion of the side surface 322 located closer to the outer diameter side than the bolt hole 35, i.e., the outer diameter side surface 3221, also tilts toward the outer side.

[0103] In such a case, by Figure 7 By forming the hub flange 32 like the hub flange 32B shown in the figure, it is possible to suppress the flange surface 321B and the side surface 322B from falling outward when the hub bolt 36 is press-fitted into the bolt hole 35B.

[0104] The hub flange 32B has a flange surface 321B facing the outside and a side surface 322B facing the inside. The flange surface 321B has an outer diameter side flange surface 3211B which is located on the outer diameter side of the bolt hole 35B. The side surface 322B has an outer diameter side side surface 3221B which is located on the outer diameter side of the bolt hole 35B.

[0105] The outer diameter side flange surface 3211B is formed as an inclined surface that is inclined toward the inner side as it approaches the outer diameter side when the hub bolt 36 is not pressed into the bolt hole 35B. The outer diameter side surface 3221B is formed as an inclined surface that is inclined toward the inner side as it approaches the outer diameter side when the hub bolt 36 is not pressed into the bolt hole 35B.

[0106] The outer flange surface 3211B has an inclination angle θ3 with respect to the radial direction, and the outer side surface 3221B has an inclination angle θ4 with respect to the radial direction. The inclination angle θ3 of the outer flange surface 3211B and the inclination angle θ4 of the outer side surface 3221B can be set to the same value or different values.

[0107] In this way, by forming the outer diameter side flange surface 3211B and the outer diameter side side surface 3221B as inclined surfaces inclined toward the inner side in advance, the outer diameter side flange surface 3211B and the outer diameter side side surface 3221B after the hub bolt 36 is pressed in can be made perpendicular to the axial direction compared to the outer diameter side flange surface 3211B and the outer diameter side side surface 3221B before the hub bolt 36 is pressed in. In addition, the parallelism between the outer diameter side flange surface 3211B and the outer diameter side side surface 3221B can be brought within a predetermined range of a specified value.

[0108] In particular, when the inclination angle θ3 of the outer diameter side flange surface 3211B and the inclination angle θ4 of the outer diameter side surface 3221B are set to different values, the inclination angle θ3 can be set to match the degree of inclination of the outer diameter side flange surface 3211B toward the outer side when the hub bolt 36 is pressed into the bolt hole 35B, and the inclination angle θ4 can be set to match the degree of inclination of the outer diameter side surface 3221B toward the outer side.

[0109] This can improve the perpendicularity of the outer diameter side flange surface 3211B and the outer diameter side surface 3221B to the axial direction after the hub bolt 36 is pressed in. In addition, the parallelism of the outer diameter side flange surface 3211B and the outer diameter side surface 3221B can be further improved.

[0110] It should be noted that, for example, the inclination angle θ3 of the outer diameter side flange surface 3211B can be set to 4', and the inclination angle θ4 of the outer diameter side surface 3221B can be set to 1'. However, the size of the inclination angle θ3 can be arbitrarily set according to the amount of the outer diameter side flange surface 3211B tilting toward the outside when the hub bolt 36 is pressed into the bolt hole 35B, and the size of the inclination angle θ4 can be arbitrarily set according to the amount of the outer diameter side surface 3221B tilting toward the outside when the hub bolt 36 is pressed into the bolt hole 35B.

[0111] [Fourth Embodiment of Hub Flange]

[0112] When the hub bolts 36 are press-fitted into the bolt holes 35 of the hub flange 32 from the inner side, the outer diameter side flange surface 3211 of the hub flange 32 may tilt inward depending on the shapes of the hub flange 32 and the hub bolts 36 .

[0113] In such a case, by Figure 8 By forming the hub flange 32 like the hub flange 32C shown, it is possible to suppress the flange surface 321C from falling inward when the hub bolts 36 are press-fitted into the bolt holes 35C.

[0114] The hub flange 32C has a flange surface 321C facing the outside and a side surface 322C facing the inside. The flange surface 321C has an outer diameter side flange surface 3211C which is a portion located on the outer diameter side of the bolt hole 35C.

[0115] like Figure 8 As shown in (a), in the hub flange 32C in a state where the hub bolts 36 are not pressed into the bolt holes 35C, the outer diameter side flange surface 3211C is formed as an inclined surface that inclines toward the outer side as it goes toward the outer diameter side. The inclination angle of the outer diameter side flange surface 3211C with respect to the radial direction is θ5.

[0116] like Figure 8 As shown in (b), the outer diameter side flange surface 3211C tilts toward the inner side due to the hub bolt 36 being pressed into the bolt hole 35C. Therefore, by pre-forming the outer diameter side flange surface 3211C as an inclined surface inclined toward the outer side, the outer diameter side flange surface 3211C after the hub bolt 36 is pressed into can be made to be a surface perpendicular to the axial direction compared to the outer diameter side flange surface 3211C before the hub bolt 36 is pressed into.

[0117] Thus, in the finished wheel bearing device 1 in which the hub bolt 36 is pressed into the bolt hole 35C, the swing and tilt of the flange surface 321C can be brought within a predetermined range, and the generation of brake judder and noise can be suppressed. In addition, by suppressing the generation of brake judder, the NVH performance of the vehicle can be improved.

[0118] For example, the inclination angle θ5 of the outer flange surface 3211C can be set to 4'. However, the magnitude of the inclination angle θ5 can be arbitrarily set according to the amount of inclination of the outer flange surface 3211C toward the inner side when the hub bolt 36 is press-fitted into the bolt hole 35C.

[0119] [Fifth Embodiment of Hub Flange]

[0120] When the hub bolt 36 is press-fitted into the bolt hole 35 of the hub flange 32 from the inside, depending on the shape of the hub flange 32 and the hub bolt 36, in addition to the outer diameter side flange surface 3211 of the hub flange 32, the outer diameter side surface 3221 may also tilt inward.

[0121] In such a case, by Fig. 9 By forming the hub flange 32 like the hub flange 32D shown, it is possible to suppress the flange surface 321D and the side surface 322D from falling inward when the hub bolt 36 is press-fitted into the bolt hole 35D.

[0122] The hub flange 32D has a flange surface 321D facing the outside and a side surface 322D facing the inside. The flange surface 321D has an outer diameter side flange surface 3211D which is located on the outer diameter side of the bolt hole 35D. The side surface 322D has an outer diameter side side surface 3221D which is located on the outer diameter side of the bolt hole 35D.

[0123] When the hub bolt 36 is not pressed into the bolt hole 35D, the outer diameter side flange surface 3211D is formed as an inclined surface that is inclined toward the outer side as it approaches the outer diameter side. When the hub bolt 36 is not pressed into the bolt hole 35D, the outer diameter side surface 3221D is formed as an inclined surface that is inclined toward the outer side as it approaches the outer diameter side.

[0124] The outer flange surface 3211D has an inclination angle θ6 with respect to the radial direction, and the outer side surface 3221D has an inclination angle θ7 with respect to the radial direction. The inclination angle θ6 of the outer flange surface 3211D and the inclination angle θ7 of the outer side surface 3221D can be set to the same value or different values.

[0125] In this way, by forming the outer diameter side flange surface 3211D and the outer diameter side side surface 3221D as inclined surfaces inclined toward the outside in advance, the outer diameter side flange surface 3211D and the outer diameter side side surface 3221D after the hub bolt 36 is pressed in can be made perpendicular to the axial direction compared to the outer diameter side flange surface 3211D and the outer diameter side side surface 3221D before the hub bolt 36 is pressed in. In addition, the parallelism between the outer diameter side flange surface 3211D and the outer diameter side side surface 3221D can be brought within a predetermined range of a specified value.

[0126] In particular, when the inclination angle θ6 of the outer diameter side flange surface 3211D and the inclination angle θ7 of the outer diameter side surface 3221D are set to different values, the inclination angle θ6 can be set to match the degree of inclination of the outer diameter side flange surface 3211D toward the inner side when the hub bolt 36 is pressed into the bolt hole 35D, and the inclination angle θ7 can be set to match the degree of inclination of the outer diameter side surface 3221D toward the inner side.

[0127] This can improve the perpendicularity of the outer diameter side flange surface 3211D and the outer diameter side surface 3221D to the axial direction after the hub bolt 36 is pressed in. In addition, the parallelism between the outer diameter side flange surface 3211D and the outer diameter side surface 3221D can be further improved.

[0128] It should be noted that, for example, the inclination angle θ6 of the outer diameter side flange surface 3211D can be set to 4', and the inclination angle θ7 of the outer diameter side surface 3221D can be set to 1'. However, the size of the inclination angle θ6 can be arbitrarily set according to the amount of inclination of the outer diameter side flange surface 3211D toward the inner side when the hub bolt 36 is pressed into the bolt hole 35D, and the size of the inclination angle θ7 can be arbitrarily set according to the amount of inclination of the outer diameter side surface 3221D toward the inner side when the hub bolt 36 is pressed into the bolt hole 35D.

[0129] It should be noted that the wheel bearing device 1 in the present embodiment can also be set as a fourth generation structure, in which, instead of forming the inner raceway surface 41 opposed to the outer raceway surface 23 of the outer ring 2 on the inner ring 4, it is formed on a constant velocity joint that is engaged with a through hole formed on the inner periphery of the hub ring 3, thereby becoming a structure without the inner ring 4. In this case, the constant velocity joint becomes a part of the inner member connected to the hub ring, and a double row of inner raceways is formed by the hub ring and the constant velocity joint.

[0130] The wheel bearing device of the fourth generation structure which does not have the inner ring 4 can be, for example, Fig.10 The wheel bearing device 1A is configured as shown in FIG. The wheel bearing device 1A includes a constant velocity joint 50 connected to the hub wheel 3A, and does not include the inner ring 4. The constant velocity joint 50 is an example of a raceway surface forming member connected to the hub wheel.

[0131] The constant velocity joint 50 includes a mouth portion 52 for supporting a shaft to which a driving force is input from a driving source, and a rod portion 53 extending outward from the mouth portion 52. The hub wheel 3A has a through hole 38 extending in the axial direction, and the through hole 38 and the rod portion 53 are spline-fitted.

[0132] An inner raceway surface 58 is formed on the outer peripheral surface of the outer end portion of the mouth 52, which faces the outer raceway surface 23 on the inner side of the outer ring 2. The inner raceway surface 58 is an example of the inner raceway surface on the other side facing the outer raceway surface. The inner ball row 5 is freely sandwiched between the outer raceway surface 23 on the inner side of the outer ring 2 and the inner raceway surface 58 of the mouth 52 in the constant velocity joint 50.

[0133] That is, in the wheel bearing device 1A, the constant velocity joint 50 having the inner raceway surface 58 facing the outer raceway surface 23 of the outer race 2 also serves as the inner race.

[0134] The embodiments of the present invention have been described above, but the present invention is not limited to such embodiments at all, but is merely illustrative, and can of course be further implemented in various ways within the scope of the present invention without departing from the gist of the present invention. The scope of the present invention is shown by the description of the patent technical solution, and also includes the equivalent meanings recorded in the patent technical solution and all changes within the scope.

Claims

1. A wheel bearing device, comprising: An outer member having a double row of outer track surfaces on the inner periphery; an inner member, which is composed of a hub ring and a raceway forming member, the hub ring having an inner raceway surface on one side facing the outer raceway surface and a hub flange for mounting a wheel, the raceway forming member being connected to the hub ring and having an inner raceway surface on the other side facing the outer raceway surface on the outer periphery; Double rows of rolling elements, which are freely accommodated between the two track surfaces of the outer member and the inner member; and Hub bolts, which are pressed into bolt holes formed in the hub flange, in, The difference between the surface hardness of the bolt hole in the hub flange and the surface hardness of the hub bolt is 42HRC to 50HRC.

2. The wheel bearing device according to claim 1, wherein: The hub bolt has a knurled portion, wherein the knurled portion is formed with a plurality of convex portions extending in the axial direction along the circumferential direction and is pressed into the bolt hole. The convex portion includes a first inclined surface and a second inclined surface which are inclined toward a side where the distance between each other in the circumferential direction decreases as the distance toward the front end side of the convex portion increases. The angle formed by the first inclined surface and the second inclined surface of the convex portion is an acute angle.

3. The wheel bearing device according to claim 1 or 2, wherein: The inner peripheral surface of the bolt hole has a plurality of recessed portions, the plurality of recessed portions being formed to have a smaller diameter than the convex portion and being able to fit with the convex portion with an interference fit.

4. The wheel bearing device according to claim 1 or 2, wherein: The hub flange has a flange surface facing one axial side, In the hub flange in a state where the hub bolts are not press-fitted into the bolt holes, a portion of the flange surface located on the outer diameter side of the bolt holes is inclined toward the other axial side as it approaches the outer diameter side.

5. The wheel bearing device according to claim 1 or 2, wherein: The hub flange has a flange surface facing one axial side, In the hub flange in a state where the hub bolts are not press-fitted into the bolt holes, a portion of the flange surface located on the outer diameter side of the bolt holes is inclined toward one axial side as it approaches the outer diameter side.

6. The wheel bearing device according to claim 1, wherein: The hub flange has a flange surface facing one axial side and a side surface facing the other axial side. In the hub flange in a state where the hub bolts are not press-fitted into the bolt holes, portions of the flange surface and the side surface located on the outer diameter side of the bolt holes are inclined toward the other axial side as they go toward the outer diameter side.

7. The wheel bearing device according to claim 1, wherein: The hub flange has a flange surface facing one axial side and a side surface facing the other axial side. In the hub flange in a state where the hub bolts are not press-fitted into the bolt holes, portions of the flange surface and the side surface located on the outer diameter side of the bolt holes are inclined toward one axial side as they go toward the outer diameter side.

8. The wheel bearing device according to claim 6 or 7, wherein: An inclination angle of the flange surface with respect to a direction perpendicular to the axial direction is different from an inclination angle of the side surface with respect to the direction perpendicular to the axial direction.

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