Bearing device for wheel

Abstract

To provide a bearing device for a wheel, which can improve slip torque resistance against a bolt hole of a hub bolt and suppress distortion of a hub flange caused by pressing-in of the hub bolt.SOLUTION: A bearing device 1 for a wheel comprises: an internal member including an outer ring 2 having a doubler row of outer orbital planes 23 and 24 in an inner periphery, a hub ring 3 having, in an outer periphery, one inner orbital plane 33 facing the outer orbital plane 24 and a hub flange 32 for fitting the wheel, and an inner ring 4 having an other inner orbital plane 41 facing the outer orbital plane 23 in the outer periphery and connected to the hub ring 3; inner and outer ball rows 5 and 6 rollably housed between both the orbital planes of the outer ring 2, the hub ring 3, and the inner ring 4; and a hub bolt 36 pressed into a bolt hole 35 formed in the hub flange 32. A difference between the surface hardness of the bolt hole 35 and the surface hardness of the hub bolt 36 in the hub flange 32 is 42 HRC-50 HRC.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, there is known a wheel bearing device that rotatably supports a wheel in a suspension system of a vehicle such as an automobile. In the wheel bearing device, a hub ring, which is an inner member, has a hub flange extending radially outward, and a hub bolt for fastening the hub ring to the wheel or the like is press-fitted into a bolt hole formed in the hub flange.

[0003] When the hub bolt is press-fitted into the bolt hole of the hub flange, if the tightening margin of the hub bolt is increased to ensure sufficient anti-slip torque for the bolt hole of the hub bolt, the hub flange is distorted, and the flange surface of the hub flange becomes more unstable and tilted. If the flange surface becomes unstable and tilted, the brake rotor fixed to the flange surface may become unstable, which may lead to brake judder and noise.

[0004] In particular, in recent years, there has been a demand for further weight reduction in wheel bearing devices in order to improve vehicle fuel efficiency, and as the weight reduction in wheel bearing devices increases, the hub flange becomes thinner, which tends to increase distortion in the hub flange.

[0005] In order to suppress distortion caused in the hub flange due to the pressing in of the hub bolts, for example, if the thermal effect of the hardened layer formed on the hub wheel extends to the portion of the hub flange where the bolt holes are formed, the distortion in the hub flange will become large, so a configuration is adopted in which the thermal effect of the hardened layer formed on the hub wheel does not extend to the portion of the hub flange where the bolt holes are formed (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2000-219006 A Summary of the Invention [Problem to be solved by the invention]

[0007] In addition, one way of suppressing distortion of the hub flange caused by pressing the hub bolt into the bolt hole is to reduce the tightening of the hub bolt relative to the bolt hole. However, reducing the tightening of the hub bolt relative to the bolt hole may result in a risk of not being able to sufficiently ensure the anti-slip torque of the hub bolt relative to the bolt hole.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and provides a wheel bearing device that can achieve both improved slip torque resistance in the bolt hole of the hub bolt and suppression of distortion of the hub flange due to pressing in of the hub bolt. [Means for solving the problem]

[0009] That is, the wheel bearing device comprises an inner member composed of an outer member having a double-row outer raceway surface on its inner circumference, a hub wheel having an inner raceway surface on its outer circumference facing the outer raceway surface and a hub flange for mounting a wheel, and a raceway surface forming member connected to the hub wheel and having an other inner raceway surface on its outer circumference facing the outer raceway surface, double-row rolling elements accommodated in a rollable manner between the raceway surfaces of the outer member and the inner member, and a hub bolt press-fitted into a bolt hole formed in the hub flange, wherein the difference in surface hardness between the bolt hole in the hub flange and the hub bolt is 42HRC to 50HRC. Effect of the Invention

[0010] According to the present invention, it is possible to improve the slip torque resistance of the hub bolt in the bolt hole and suppress deformation occurring in the hub flange. [Brief description of the drawings]

[0011] [Figure 1] 1 is a side cross-sectional view showing a wheel bearing device. [Diagram 2] FIG. 4 is a side cross-sectional view showing a hub bolt and a bolt hole in the hub flange. [Diagram 3] FIG. 4 is an axial cross-sectional view showing a knurled portion of the hub bolt. [Figure 4] 4 is an axial cross-sectional view showing a convex portion of a knurled portion of a hub bolt and a concave portion of a bolt hole in a hub flange. FIG. [Diagram 5] 4 is a side cross-sectional view showing a state in which a hub bolt is press-fitted into a bolt hole in a hub flange. FIG. [Figure 6] FIG. 11 is a side cross-sectional view showing a second embodiment of the hub flange. [Figure 7] FIG. 11 is a side cross-sectional view showing a third embodiment of the hub flange. [Figure 8] FIG. 11 is a side cross-sectional view showing a fourth embodiment of the hub flange. [Figure 9] FIG. 11 is a side cross-sectional view showing a fifth embodiment of the hub flange. [Figure 10] FIG. 2 is a side cross-sectional view showing a wheel bearing device having a fourth-generation structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0013] [Wheel bearing device] A wheel bearing device 1 shown in FIG. 1 is one embodiment of a wheel bearing device according to the present invention, and supports a wheel rotatably in a suspension system of a vehicle such as an automobile.

[0014] In the following description, the axial direction refers to the direction along the rotation axis X of the wheel support bearing device 1. The outer side refers to one axial side, which is the wheel side of the wheel support bearing device 1 when mounted on a vehicle body, and the inner side refers to the other axial side, which is the vehicle body side of the wheel support bearing device 1 when mounted on the vehicle body.

[0015] The wheel bearing device 1 has a configuration called third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, two rolling rows of inner ball rows 5 and outer ball rows 6, an outer seal member 9, and an inner seal member 10. The inner ring 4 is an example of a raceway surface forming member connected to the hub ring.

[0016] An inner side opening 21 is formed at the inner side end of the outer ring 2, into which the inner side seal member 10 can be fitted. An outer side opening 22 is formed at the outer side end of the outer ring 2, into which the outer side seal member 9 can be fitted.

[0017] The inner side seal member 10 is fitted into the inner side opening 21 to close 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 inner ring 4 as the inner members. The outer side seal member 9 is fitted into the outer side opening 22 to close the outer side opening end of the annular space S.

[0018] The inner seal member 10 and the outer seal member 9 are sealing devices that close the open ends of the annular space S. In this manner, by closing the open ends on the inner side and the outer side of the annular space S with the inner seal member 10 and the outer seal member 9, foreign matter such as muddy water is prevented from entering the inside of the wheel bearing device 1.

[0019] An inner-side outer raceway surface 23 and an outer-side outer raceway surface 24 are formed on the inner peripheral surface of the outer ring 2. A vehicle body mounting flange 25 for mounting the outer ring 2 to a vehicle body member is integrally formed on the outer peripheral surface of the outer ring 2. The vehicle body mounting flange 25 is provided with bolt holes 26 into which fastening members (here, bolts) that fasten the vehicle body member and the outer ring 2 are screwed.

[0020] A small diameter step 31 that is smaller in diameter than the outer end is formed at the inner end of the outer peripheral surface of the hub wheel 3. A hub flange 32 for mounting a wheel is integrally formed at the outer end of the hub wheel 3. The hub flange 32 extends outwardly from the outer end, which is one end of the hub wheel 3 in the axial direction.

[0021] A plurality of bolt holes 35 are formed in the hub flange 32. The bolt holes 35 axially penetrate the hub flange 32. Hub bolts 36 for fastening the hub wheel 3 to a wheel or a brake component are press-fitted into the bolt holes 35.

[0022] The hub flange 32 has a flange surface 321 facing the outer side and a side surface 322 facing the inner side. The flange surface 321 and the side surface 322 are surfaces that extend in a direction perpendicular to the axial direction. A 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).

[0023] In the hub ring 3, a sliding surface 34 with which the outer seal member 9 slides is formed on the base side of the hub flange 32. An outer-side inner raceway surface 33 is provided on the outer circumferential surface of the hub ring 3 so as to face the outer side outer raceway surface 24 of the outer ring 2. In other words, the inner raceway surface 33 is formed by the hub ring 3 on the outer side of the inner member. The inner raceway surface 33 is an example of one of the inner raceways that faces the outer raceway surface.

[0024] An inner ring 4 is provided on the small diameter step 31 of the hub wheel 3. The inner ring 4 is fixed to the small diameter step 31 of the hub wheel 3 by press fitting only, or by press fitting and crimping. Fig. 1 shows an example of crimping, where a crimped portion 37 is formed at the inner side end of the hub wheel 3, which is crimped to the inner side end face 42 of the inner ring 4.

[0025] The inner ring 4 is fixed in the axial direction by a crimped portion 37. The crimped portion 37 is formed by plastically deforming the inner end portion of the small diameter step portion 31 toward the outer diameter side. The inner ring 4 applies a preload to the inner ball row 5 and the outer ball row 6, which are the rolling rows.

[0026] An inner-side inner raceway surface 41 is provided on the outer peripheral surface of the inner ring 4 so as to face the inner-side outer raceway surface 23 of the outer ring 2. In other words, on the inner side of the inner member, the inner raceway surface 41 is formed by the inner ring 4. The inner raceway surface 41 is an example of the other inner raceway surface facing the outer raceway surface.

[0027] The inner ball row 5 and outer ball row 6, which are rolling rows, are formed by a plurality of balls 7, which are rolling elements, being held by a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway surface 41 of the inner ring 4 and the inner-side outer raceway surface 23 of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway surface 33 of the hub ring 3 and the outer raceway surface 24 of the outer ring 2. In other words, the inner ball row 5 and the outer ball row 6 are rollably housed between the raceway surfaces of the outer member and the inner member.

[0028] In the wheel bearing device 1, a double-row angular ball bearing is formed by the outer ring 2, hub ring 3, inner ring 4, inner ball row 5, and outer ball row 6. Note that the wheel bearing device 1 may be formed as a double-row tapered roller bearing instead of the double-row angular ball bearing.

[0029] [Hub bolts and hub flange bolt holes] 2, the hub bolt 36 has a head 36A, a knurled portion 36B, and a male threaded portion 36C. The head 36A is disposed at the inner end of the hub bolt 36, and is located on the inner side of the hub flange 32 when the hub bolt 36 is press-fitted into the bolt hole 35.

[0030] The knurl portion 36B is a portion that is press-fitted into the bolt hole 35 of the hub bolt 36, and a plurality of protrusions 361 extending in the axial direction are formed along the circumferential direction on the knurl portion 36B (see FIG. 3). The knurl portion 36B is disposed adjacent to the outer side of the head portion 36A.

[0031] The male thread portion 36C is located adjacent to the outer side of the knurl portion 36B. By screwing a nut onto the male thread portion 36C of the hub bolt 36 press-fitted into the bolt hole 35, the hub wheel 3 and the wheel or brake component can be fastened together.

[0032] The knurled portion 36B of the hub bolt 36 has a tightening margin with respect to 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.

[0033] By press-fitting the knurled portion 36B into the bolt hole 35, the protrusion 361 of the knurled portion 36B bites into the inner circumferential surface of the bolt hole 35 in the hub flange 32, and the inner circumferential surface of the bolt hole 35 is plastically deformed along the shape of the protrusion 361. This prevents the hub bolt 36 from rotating circumferentially relative to the bolt hole 35.

[0034] The wheel bearing device 1 is configured so that the difference in surface hardness between the knurled portion 36B of the hub bolt 36 and the surface hardness of the inner circumferential surface of the bolt hole 35 of the hub flange 32 is 42HRC to 50HRC.

[0035] In this case, the surface hardness of the knurl portion 36B can be obtained, for example, by measuring the hardness at multiple locations at a depth of 0.05 mm to 0.1 mm from the outer peripheral surface 360 ​​of the knurl portion 36B including the convex portion 361 (see the "X" marks in Figure 3).

[0036] Similarly, the surface hardness of the inner circumferential surface of bolt hole 35 can be obtained by measuring the hardness at a plurality of points at a depth of 0.05 mm to 0.1 mm from the inner circumferential surface of bolt hole 35.

[0037] In this way, by setting the difference in surface hardness between the knurl portion 36B and the surface hardness of the inner surface of the bolt hole 35 to 42HRC to 50HRC, the knurl portion 36B can easily bite into the inner surface of the bolt hole 35, thereby increasing the degree of adhesion between the knurl portion 36B and the inner surface of the bolt hole 35.

[0038] This increases the degree to which rotation of the hub bolt 36 in the circumferential direction relative to the bolt hole 35 is suppressed, making it possible to improve the slip resistance torque of the hub bolt 36 in the circumferential direction relative to the bolt hole 35.

[0039] Furthermore, since the slip resistance torque of the hub bolt 36 relative to the bolt hole 35 is improved, the necessary slip resistance torque can be ensured even if the tightening margin of the knurl portion 36B relative to the bolt hole 35 is reduced.

[0040] When the hub bolt 36 is pressed into the bolt hole 35, the hub flange 32 is strained and deformed, but by reducing the clamping margin of the knurl portion 36B relative to the bolt hole 35, it is possible to suppress the deformation occurring in the hub flange 32.

[0041] In this embodiment, the difference in surface hardness between the knurl portion 36B and the inner surface of the bolt hole 35 is set in the range of 42HRC to 50HRC. If the difference in surface hardness is less than 42HRC, there is a risk that the knurl portion 36B will not be able to sufficiently penetrate into the bolt hole 35.

[0042] Furthermore, if the difference in surface hardness exceeds 50 HRC, when a rotational force is applied to the hub bolt 36, the inner surface of the bolt hole 35 will be prone to circumferential deformation, which may make it difficult to ensure sufficient slip resistance torque.

[0043] 3, the protrusion 361 of the knurl portion 36B is formed in a mountain shape protruding from the outer circumferential surface 360 ​​of the knurl portion 36B toward the outer diameter side. The protrusion 361 has a first inclined surface 361a and a second inclined surface 361b that are inclined toward the side where the distance between them in the circumferential direction becomes smaller toward the tip side of the protrusion 361, and the angle θ1 formed by the first inclined surface 361a and the second inclined surface 361b of the protrusion 361 is an acute angle. In this embodiment, the angle θ1 is set in the range of 50° to 80°.

[0044] In this way, by setting the angle θ1 between the first inclined surface 361a and the second inclined surface 361b to an acute angle, the convex portion 361 of the knurl portion 36B can easily bite into the inner surface of the bolt hole 35, thereby increasing the degree of adhesion between the knurl portion 36B and the inner surface of the bolt hole 35.

[0045] This increases the degree to which rotation of the hub bolt 36 in the circumferential direction relative to the bolt hole 35 is suppressed, making it possible to improve the slip resistance torque of the hub bolt 36 in the circumferential direction relative to the bolt hole 35.

[0046] In addition, since the slip resistance torque of the hub bolt 36 in the bolt hole 35 is improved, the necessary slip resistance torque can be ensured even if the tightening margin of the knurl portion 36B in the bolt hole 35 is reduced. By reducing the tightening margin of the knurl portion 36B in the bolt hole 35, it is possible to suppress deformation occurring in the hub flange 32.

[0047] As shown in Fig. 4, a male spline is formed in the knurl portion 36B of the hub bolt 36 by a plurality of protrusions 361. A plurality of axially extending recesses 351 are formed along the circumferential direction on the inner peripheral surface of the bolt hole 35 in the hub flange 32, and a female spline is formed by the plurality of recesses 351. The recesses 351 of the bolt hole 35 and the protrusions 361 of the knurl portion 36B can be spline-fitted.

[0048] The recess 351 of the bolt hole 35 that can be spline-fitted into the protrusion 361 of the knurl portion 36B is formed to have a smaller diameter than the protrusion 361 and has a tightening margin n with respect to the protrusion 361. Therefore, when the protrusion 361 and the recess 351 are fitted together, the protrusion 361 is press-fitted into the recess 351.

[0049] 4 and 5, when the convex portion 361 is press-fitted into the concave portion 351, the convex portion 361 bites into the concave portion 351, and the shape of the convex portion 361 is transferred to the inner peripheral surface of the concave portion 351. In this case, the inner peripheral surface of the concave portion 351 is very slightly cut by the convex portion 361, and the shape of the convex portion 361 is transferred to the inner peripheral surface of the concave portion 351 while concomitantly causing very slight plastic deformation and elastic deformation.

[0050] When the projection 361 is press-fitted into the recess 351 and the projection 361 and the recess 351 are spline-fitted together, the outer circumferential surface of the projection 361 and the inner circumferential surface of the recess 351 are in close contact with each other overall.

[0051] In this way, by spline-fitting the convex portion 361 and the concave portion 351 in a state of total close contact in the axial direction, the slip resistance torque in the circumferential direction of the hub bolt 36 with respect to the bolt hole 35 can be increased.

[0052] In addition, because the slip resistance torque of the hub bolt 36 in the bolt hole 35 is increased, the necessary slip resistance torque can be ensured even if the tightening margin of the knurl portion 36B in the bolt hole 35 is reduced. By reducing the tightening margin of the knurl portion 36B in the bolt hole 35, it is possible to suppress deformation occurring in the hub flange 32.

[0053] [Second embodiment of hub flange] When hub bolts 36 are press-fitted into bolt holes 35 of hub flange 32 from the inner side, flange surface 321 of hub flange 32 may deform and fall toward the outer side. In particular, outer diameter side flange surface 3211, which is a portion of flange surface 321 located on the outer diameter side of bolt holes 35, is prone to falling toward the outer side when hub bolts 36 are press-fitted into bolt holes 35.

[0054] In the wheel bearing device 1, by forming the hub flange 32 as the hub flange 32A shown in FIG. 6, it is possible to prevent the flange surface 321A from falling toward the outer side when the hub bolt 36 is press-fitted into the bolt hole 35.

[0055] The hub flange 32A has a flange surface 321A facing the outer side and a side surface 322A facing the inner side. 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 holes 35A.

[0056] 6(a), in the hub flange 32A when the hub bolts 36 are not press-fitted into the bolt holes 35A, the outer diameter side flange surface 3211A is formed as an inclined surface that inclines toward the inner side as it approaches the outer diameter side. The inclination angle of the outer diameter side flange surface 3211A with respect to the radial direction is θ2. The radial direction is perpendicular to the axial direction.

[0057] As shown in Figure 6(b), outer diameter side flange surface 3211A tilts toward the outer side when hub bolt 36 is pressed into bolt hole 35A. Therefore, by forming outer diameter side flange surface 3211A in advance as an inclined surface that slopes toward the inner side, outer diameter side flange surface 3211A after hub bolt 36 is pressed in can be made to be a surface that is more perpendicular to the axial direction than outer diameter side flange surface 3211A before hub bolt 36 is pressed in.

[0058] As a result, in the wheel bearing device 1 in its finished state with the hub bolt 36 pressed into the bolt hole 35A, the wobble and tilt of the flange surface 321A can be kept within a predetermined specified value range, making it possible to suppress the occurrence of brake judder and noise.

[0059] In addition, suppressing the occurrence of brake judder can improve the vehicle's NVH performance. Note that the "N" in NVH performance stands for "Noise," "V" for "Vibration," and "H" for "Harshness."

[0060] For example, the inclination angle θ2 of the outer diameter side flange surface 3211A can be set to 4'. However, the magnitude of the inclination angle θ2 can be set arbitrarily depending on the amount of inclination of the outer diameter side flange surface 3211A toward the outer side when the hub bolt 36 is press-fitted into the bolt hole 35A.

[0061] [Third embodiment of hub flange] When the hub bolt 36 is pressed into the bolt hole 35 of the hub flange 32 from the inner side, depending on the shapes 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, which is the portion of the side surface 322 located on the outer diameter side of the bolt hole 35, may fall toward the outer side.

[0062] In such a case, by forming the hub flange 32 as hub flange 32B shown in Figure 7, it is possible to prevent flange surface 321B and side surface 322B from falling toward the outer side when hub bolt 36 is pressed into bolt hole 35B.

[0063] Hub flange 32B has flange surface 321B facing the outer side and side surface 322B facing the inner side. Flange surface 321B has outer diameter side flange surface 3211B which is a portion located on the outer diameter side of bolt holes 35B. Side surface 322B has outer diameter side surface 3221B which is a portion located on the outer diameter side of bolt holes 35B.

[0064] Outer diameter side flange surface 3211B is formed as an inclined surface that slopes inwardly toward the outer diameter side when hub bolt 36 is not press-fitted into bolt hole 35B. Outer diameter side surface 3221B is formed as an inclined surface that slopes inwardly toward the outer diameter side when hub bolt 36 is not press-fitted into bolt hole 35B.

[0065] The inclination angle θ3 of the outer diameter side flange surface 3211B with respect to the radial direction is θ3, and the inclination angle θ4 of the outer diameter side surface 3221B with respect to the radial direction can be set to the same value or to different values.

[0066] In this way, by previously forming both the outer diameter side flange surface 3211B and the outer diameter side surface 3221B as inclined surfaces that slope toward the inner side, the outer diameter side flange surface 3211B and the outer diameter side surface 3221B after the hub bolt 36 is pressed in can be made to be surfaces that are more perpendicular to the axial direction than the outer diameter side flange surface 3211B and the outer diameter side surface 3221B before the hub bolt 36 is pressed in. Also, it becomes possible to keep the parallelism between the outer diameter side flange surface 3211B and the outer diameter side surface 3221B within a predetermined range of specified values.

[0067] 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 in accordance with the degree to which the outer diameter side flange surface 3211B tilts toward the outer side when the hub bolt 36 is pressed into the bolt hole 35B, and the inclination angle θ4 can be set in accordance with the degree to which the outer diameter side surface 3221B tilts toward the outer side.

[0068] This makes it possible to increase both the perpendicularity of the outer diameter side flange surface 3211B to the axial direction and the perpendicularity of the outer diameter side surface 3221B to the axial direction after the hub bolt 36 is press-fitted. Also, it is possible to further increase the parallelism between the outer diameter side flange surface 3211B and the outer diameter side surface 3221B.

[0069] For example, inclination angle θ3 of outer diameter side flange surface 3211B can be set to 4', and inclination angle θ4 of outer diameter side surface 3221B can be set to 1'. However, the magnitude of inclination angle θ3 can be set arbitrarily depending on the amount of inclination of outer diameter side flange surface 3211B to the outer side when hub bolt 36 is press-fitted into bolt hole 35B, and the magnitude of inclination angle θ4 can be set arbitrarily depending on the amount of inclination of outer diameter side surface 3221B to the outer side when hub bolt 36 is press-fitted into bolt hole 35B.

[0070] [Fourth embodiment of hub flange] When hub bolts 36 are press-fitted into bolt holes 35 of hub flange 32 from the inner side, depending on the shapes of hub flange 32 and hub bolts 36, outer diameter flange surface 3211 of hub flange 32 may collapse toward the inner side.

[0071] In such a case, by forming hub flange 32 as hub flange 32C shown in FIG. 8, it is possible to prevent flange surface 321C from falling toward the inner side when hub bolt 36 is press-fitted into bolt hole 35C.

[0072] The hub flange 32C has a flange surface 321C facing the outer side and a side surface 322C facing the inner side. 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 holes 35C.

[0073] 8(a), in the hub flange 32C in a state in which the hub bolts 36 are not press-fitted 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 approaches the outer diameter side. The inclination angle of the outer diameter side flange surface 3211C with respect to the radial direction is θ5.

[0074] As shown in Figure 8 (b), since outer diameter side flange surface 3211C tilts toward the inner side when hub bolt 36 is pressed into bolt hole 35C, by forming outer diameter side flange surface 3211C in advance as an inclined surface that slopes toward the outer side, outer diameter side flange surface 3211C after hub bolt 36 is pressed in can be made to be a surface that is more perpendicular to the axial direction than outer diameter side flange surface 3211C before hub bolt 36 is pressed in.

[0075] As a result, in the wheel bearing device 1 in a completed state in which the hub bolts 36 are press-fitted into the bolt holes 35C, the runout and tilt of the flange surface 321C can be kept within a predetermined range, making it possible to suppress the occurrence of brake judder and noise. Furthermore, by suppressing the occurrence of brake judder, the NVH performance of the vehicle can be improved.

[0076] For example, the inclination angle θ5 of the outer diameter side flange surface 3211C can be set to 4'. However, the magnitude of the inclination angle θ5 can be set arbitrarily depending on the amount of inclination of the outer diameter side flange surface 3211C toward the inner side when the hub bolt 36 is press-fitted into the bolt hole 35C.

[0077] [Fifth embodiment of hub flange] When the hub bolt 36 is pressed into the bolt hole 35 of the hub flange 32 from the inner side, depending on the shapes 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 side surface 3221 may also fall toward the inner side.

[0078] In such a case, by forming hub flange 32 as hub flange 32D shown in Figure 9, it is possible to prevent flange surface 321D and side surface 322D from falling toward the inner side when hub bolt 36 is pressed into bolt hole 35D.

[0079] Hub flange 32D has flange surface 321D facing the outer side and side surface 322D facing the inner side. Flange surface 321D has outer diameter side flange surface 3211D which is a portion located on the outer diameter side of bolt holes 35D. Side surface 322D has outer diameter side surface 3221D which is a portion located on the outer diameter side of bolt holes 35D.

[0080] Outer diameter side flange surface 3211D is formed as an inclined surface that slopes toward the outer side as it approaches the outer diameter side when hub bolt 36 is not press-fitted into bolt hole 35D. Outer diameter side side surface 3221D is formed as an inclined surface that slopes toward the outer side as it approaches the outer diameter side when hub bolt 36 is not press-fitted into bolt hole 35D.

[0081] The inclination angle θ6 of the outer diameter side flange surface 3211D with respect to the radial direction is θ6, and the inclination angle θ7 of the outer diameter side surface 3221D with respect to the radial direction is θ7. The inclination angle θ6 of the outer diameter side flange surface 3211D and the inclination angle θ7 of the outer diameter side surface 3221D can be set to the same value or can be set to different values.

[0082] In this way, by previously forming both the outer diameter side flange surface 3211D and the outer diameter side surface 3221D into an inclined surface that slopes toward the outer side, the outer diameter side flange surface 3211D and the outer diameter side surface 3221D after the hub bolt 36 is pressed in can be made to be surfaces that are more perpendicular to the axial direction than the outer diameter side flange surface 3211D and the outer diameter side surface 3221D before the hub bolt 36 is pressed in. Also, it becomes possible to keep the parallelism between the outer diameter side flange surface 3211D and the outer diameter side surface 3221D within a predetermined range of specified values.

[0083] 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 in accordance with the degree to which the outer diameter side flange surface 3211D tilts toward the inner side when the hub bolt 36 is pressed into the bolt hole 35D, and the inclination angle θ7 can be set in accordance with the degree to which the outer diameter side surface 3221D tilts toward the inner side.

[0084] This makes it possible to increase both the perpendicularity of the outer diameter side flange surface 3211D to the axial direction and the perpendicularity of the outer diameter side surface 3221D to the axial direction after the hub bolt 36 is press-fitted. Also, the parallelism between the outer diameter side flange surface 3211D and the outer diameter side surface 3221D can be further increased.

[0085] For example, inclination angle θ6 of outer diameter side flange surface 3211D can be set to 4', and inclination angle θ7 of outer diameter side surface 3221D can be set to 1'. However, the magnitude of inclination angle θ6 can be set arbitrarily depending on the amount of inclination of outer diameter side flange surface 3211D toward the inner side when hub bolt 36 is press-fitted into bolt hole 35D, and the magnitude of inclination angle θ7 can be set arbitrarily depending on the amount of inclination of outer diameter side surface 3221D toward the inner side when hub bolt 36 is press-fitted into bolt hole 35D.

[0086] Incidentally, the wheel bearing device 1 in this embodiment can also have a fourth-generation structure in which, instead of forming the inner raceway surface 41 opposing the outer raceway surface 23 of the outer ring 2 on the inner ring 4, it is formed on a constant velocity universal joint that fits into a through hole formed in the inner circumference of the hub ring 3, and is configured without the inner ring 4. In this case, the constant velocity universal joint becomes part of the inner member connected to the hub ring, and the hub ring and the constant velocity universal joint form a double-row inner raceway surface.

[0087] A wheel bearing device of the fourth generation structure not including an inner ring 4 can be configured, for example, as a wheel bearing device 1A shown in Fig. 10. The wheel bearing device 1A includes a constant velocity universal joint 50 connected to a hub wheel 3A, and does not include an inner ring 4. The constant velocity universal joint 50 is an example of a raceway surface forming member connected to a hub wheel.

[0088] Constant velocity universal joint 50 includes a mouth portion 52 that supports a shaft to which driving force is input from a drive source, and a stem portion 53 that extends toward the outer side from mouth portion 52. Hub wheel 3A has through hole 38 that passes through in the axial direction, and through hole 38 and stem portion 53 are spline-fitted.

[0089] An inner raceway surface 58 that faces the inner outer raceway surface 23 of the outer ring 2 is formed on the outer peripheral surface of the outer end of the mouth portion 52. The inner raceway surface 58 is an example of the other inner raceway surface that faces the outer raceway surface. The inner ball row 5 is rollably sandwiched between the inner outer raceway surface 23 of the outer ring 2 and the inner raceway surface 58 of the mouth portion 52 of the constant velocity universal joint 50.

[0090] That is, in the wheel bearing device 1A, the constant velocity universal joint 50 having the inner raceway surface 58 opposing the outer raceway surface 23 of the outer ring 2 also serves as the inner ring.

[0091] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely illustrative, and it goes without saying that the present invention can be embodied in various other forms without departing from the gist of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Explanation of symbols]

[0092] 1 Wheel bearing device 2 Outer ring 3 Hub wheel 4. Inner Circle 5 Inner ball row 6 Outer ball row 23 (inner side) outer raceway 24 (Outer side) outer raceway 32, 32A, 32B, 32C, 32D Hub flange 33 Inner raceway surface 35, 35A, 35B, 35C, 35D Bolt holes 36 Hub bolt 36B Naal Department 41 Inner raceway surface 321, 321A, 321B, 321C, 321D flange surface 322, 322A, 322B, 322C, 322D side 351 Recess 361 Convex 361a 1st slope 361b 2nd slope 3211, 3211A, 3211B, 3211C, 3211CD Outer diameter flange surface 3221, 3221B, 3221D Outer diameter side θ1 (angle between the first inclined surface and the second inclined surface) θ3, θ6 (Inclination angle relative to the radial direction of the outer flange surface) θ4, θ7 (Inclination angle with respect to the radial direction of the outer diameter side surface)

Claims

1. an outer member having a double row outer raceway surface on an inner periphery thereof; an inner member including a hub wheel having, on its outer periphery, one inner raceway surface opposing the outer raceway surface and a hub flange for mounting a wheel; and a raceway surface forming member connected to the hub wheel and having, on its outer periphery, the other inner raceway surface opposing the outer raceway surface; a double row of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member; a hub bolt press-fitted into a bolt hole formed in the hub flange; A wheel bearing device comprising: The difference between the surface hardness of the bolt hole in the hub flange and the surface hardness of the hub bolt is 42 HRC to 50 HRC.

2. The hub bolt has a knurled portion that is press-fitted into the bolt hole and has a plurality of axially extending protrusions formed along a circumferential direction. The protrusion has a first inclined surface and a second inclined surface that are inclined such that a distance between them in a circumferential direction decreases toward a tip side of the protrusion, 2. The wheel bearing device according to claim 1, wherein the angle between the first inclined surface and the second inclined surface of the protruding portion is an acute angle.

3. 3. The wheel bearing device according to claim 1, wherein an inner circumferential surface of the bolt hole is formed to have a smaller diameter than the protrusion and has a plurality of recesses that can be fitted with the protrusion with an interference.

4. The hub flange has a flange surface facing one axial direction, 3. A wheel bearing device as described in claim 1 or claim 2, wherein in the hub flange when the hub bolt is not pressed into the bolt hole, a portion of the flange surface located on the outer diameter side of the bolt hole is inclined axially toward the other side as it approaches the outer diameter side.

5. The hub flange has a flange surface facing one axial direction, 3. A wheel bearing device as described in claim 1 or claim 2, wherein in the hub flange when the hub bolt is not pressed into the bolt hole, a portion of the flange surface located on the outer diameter side of the bolt hole is inclined to one axial side as it approaches the outer diameter side.

6. The hub flange has a flange surface facing one axial side and a side surface facing the other axial side, 2. A wheel bearing device as described in claim 1, wherein, in the hub flange when the hub bolt is not pressed into the bolt hole, the portions of the flange surface and the side surface located radially outward from the bolt hole are inclined axially toward the other side as they approach the radially outward.

7. The hub flange has a flange surface facing one axial side and a side surface facing the other axial side, 2. A wheel bearing device as described in claim 1, wherein, in the hub flange when the hub bolt is not pressed into the bolt hole, the portions of the flange surface and the side surface located radially outward from the bolt hole are inclined axially to one side as they approach the radially outward.

8. 8. The wheel bearing device according to claim 6, 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 a direction perpendicular to the axial direction.

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