Bearing device for wheel

Abstract

Provided is a wheel bearing device capable of reducing circumferential stress generated in an inner ring. A bearing device (1) for a wheel is provided with: an outer ring (2) having outer raceway surfaces (2c, 2d); an inner member comprising a hub ring (3) having a small-diameter stepped section (3a) and an inner ring (4) into which the small-diameter stepped section (3a) is press-fitted, the inner member having inner raceway surfaces (3c, 4a) facing the outer raceway surfaces (2c, 2d); and a plurality of ball rows (5, 6) which are housed between the outer ring (2) and both raceway surfaces of the inner member, and which fix the inner ring (4) in the axial direction by means of a caulking section (3h) formed by plastically deforming the end of the small-diameter stepped section (3a) on one side in the axial direction toward the outer diameter side. The inner ring (4) has an inner peripheral surface (4d), an inner-side end surface (4b), and an inner-diameter chamfered section (4f) which connects the inner peripheral surface (4d) and the inner-side end surface (4b) and which expands in diameter toward one side in the axial direction, and the caulking section (3h) is an unquenched section which is not subjected to quenching processing, and has an annular groove (31) separated from the inner ring (4).

Description

Technical Field

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

[0002] Conventionally, wheel bearing devices are known that rotatably support wheels in suspension systems of automobiles and the like. Some wheel bearing devices have a structure in which an inner ring is press-fitted into a small-diameter step portion of a hub ring, serving as an inner member, and the inner ring is axially secured by a rivet formed by plastically deforming one axial end portion of the small-diameter step toward the outer diameter.

[0003] In the wheel bearing device having a caulking portion formed on the small-diameter step portion of the hub ring, when one end portion of the small-diameter step portion is plastically deformed toward the outer diameter side, circumferential stress is generated in the inner ring, and the inner diameter of the inner ring may expand.

[0004] In addition, an outer diameter chamfered portion is formed at the end portion on one axial side of the outer peripheral surface of the inner ring. If there is collision damage on the outer diameter chamfered portion, the circumferential stress generated in the inner ring will promote stress concentration on the collision damage, and cracks will be generated in the inner ring starting from the collision damage, which may reduce the durability of the wheel bearing device.

[0005] To suppress the occurrence of cracks originating from impact damage in the chamfered portion of the inner ring's outer diameter, one approach is to increase the axial and radial lengths of the inner ring to reduce the circumferential stress generated in the inner ring. However, increasing the axial and radial lengths of the inner ring increases the weight of the wheel bearing assembly, which can lead to a decrease in the vehicle's fuel efficiency and is therefore not desirable.

[0006] Therefore, conventionally, as disclosed in Patent Document 1, the outer diameter chamfered portion of the inner ring is subjected to heat treatment and then cut to form a re-cut surface, thereby removing the collision damage on the outer diameter chamfered portion of the inner ring.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 4471150 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] However, even after the impact damage is removed by cutting after heat treatment, impact damage may sometimes occur again on the outer diameter chamfer of the inner ring. If impact damage occurs again, cracks may still be generated due to the circumferential stress generated in the inner ring.

[0012] In addition, when the inner diameter of the inner ring expands due to circumferential stress, the inner ring expands toward the outer diameter side, the size of the inner raceway surface formed on the inner ring changes, the clearance accuracy between the inner raceway surface of the inner ring and the rolling element decreases, and the life of the wheel bearing device may be reduced.

[0013] The present invention has been made in view of the above-mentioned circumstances, and provides a wheel bearing device capable of reducing the circumferential stress generated in the inner ring in a structure in which the inner ring is fixed by a caulking portion of the hub ring.

[0014] Means for solving problems

[0015] The camshaft is a hub mounted on a wheel support frame and has a plurality of inner raceways opposite to the hub and the inner race, and the camshaft is a hub mounted on a wheel support frame. The camshaft is a hub mounted on a wheel support frame and has a plurality of inner raceways opposite to the hub and the inner race. The camshaft is a hub mounted on a wheel support frame and has a plurality of inner raceways opposite to the hub and the inner race. The camshaft is a hub mounted on a wheel support frame and has a plurality of inner raceways opposite to the hub and the inner race.

[0016] Effects of the Invention

[0017] According to the present invention, the circumferential stress generated in the inner ring can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a side sectional view showing a wheel bearing device.

[0019] Figure 2 It is a side cross-sectional view showing the vicinity of a caulking portion of a hub wheel in the wheel bearing device.

[0020] Figure 3 It is a side cross-sectional view of the wheel bearing device showing a state in which no caulking portion is formed on the small-diameter step portion of the hub wheel.

[0021] Figure 4 It is a side cross-sectional view of the small-diameter step portion showing a state where no caulking portion is formed and the outer end of the annular groove is located on the outer side of the boundary point P3 of the inner ring.

[0022] Figure 5It is a side cross-sectional view of the small-diameter step portion showing a state where no caulking portion is formed and the outer side end of the annular groove is located at the same position as the boundary point P3 of the inner ring.

[0023] Figure 6 These are diagrams showing stress distribution in the caulking portion and the inner ring. (a) is a diagram showing a case where the caulking portion does not have an annular groove, and (b) is a diagram showing a case where the caulking portion has an annular groove.

[0024] Figure 7 It is a side sectional view showing the inner diameter chamfered portion of the inner ring.

[0025] Figure 8 It is a side sectional view showing the outer diameter chamfered portion of the inner ring.

[0026] Figure 9 This is a side sectional view showing the relationship between the axial length of the straight surface of the inner ring and the radial length of the inner ring.

[0027] Description of reference numerals:

[0028] 1Wheel bearing device

[0029] 2 outer ring

[0030] 2c (Inner side) outer track surface

[0031] 2d (outer side) outer track surface

[0032] 3 wheel hubs

[0033] 3a trail steps

[0034] 3c (hub rim) inner raceway surface

[0035] 3h riveting department

[0036] 4 inner ring

[0037] 4a Inner raceway surface (of the inner ring)

[0038] 4b inner side end surface

[0039] 4d inner surface

[0040] 4e Face

[0041] 4f inner diameter chamfer

[0042] 4g outer diameter chamfer

[0043] 5 internal side ball rows

[0044] 6 external side ball rows

[0045] 7 balls

[0046] 31 annular groove

[0047] 32 first outer peripheral surface

[0048] 41 inner diameter taper

[0049] 42 inner diameter arc surface

[0050] 43 outer diameter cone

[0051] 44 outer diameter arc surface

[0052] θ1 (inner diameter tapered surface) inclination angle

[0053] θ2 (outer diameter taper) inclination angle

[0054] R (outer diameter arc surface) curvature radius

[0055] s (straight) axial length

[0056] t is the radial length between the straight surface of the inner ring and the inner circumference. DETAILED DESCRIPTION

[0057] Hereinafter, embodiments of the present invention will be described using the accompanying drawings.

[0058] [Wheel bearing device]

[0059] Figure 1 The wheel bearing device 1 shown is one embodiment of the wheel bearing device of the present invention, and is used to rotatably support a wheel in a suspension system of a vehicle such as an automobile.

[0060] In the following description, the axial direction refers to the direction along the rotation axis X of the wheel bearing device 1, the radial direction refers to the direction perpendicular to the rotation axis X of the wheel bearing device 1, and the circumferential direction refers to the direction along an arc centered on the rotation axis X of the wheel bearing device 1. Furthermore, the inner side refers to one axial side, which is the vehicle body side of the wheel bearing device 1 when mounted on a vehicle body, and the outer side refers to the other axial side, which is the wheel side of the wheel bearing device 1 when mounted on a vehicle body.

[0061] The wheel bearing device 1 has a structure known as the third generation, comprising an outer ring 2 as an outer component, a hub ring 3 and an inner ring 4 as inner components, an inner side ball row 5 and an outer side ball row 6 as two rolling rows, an inner side sealing component 9, and an outer side sealing component 10.

[0062] An inner opening 2a into which the inner sealing member 9 can be fitted is formed at the inner end of the outer ring 2. An outer opening 2b into which the outer sealing member 10 can be fitted is formed at the outer end of the outer ring 2.

[0063] The annular space S inside the bearing is sealed by fitting an inner side sealing member 9 into the inner side opening portion 2a, which becomes the inner side opening end, of the annular space S formed by the outer ring 2 and the hub ring 3, and fitting an outer side sealing member 10 into the outer side opening portion 2b, which becomes the outer side opening end of the annular space S.

[0064] The inner circumferential surface 2p of the outer ring 2 is formed with an inner outer raceway surface 2c and an outer outer raceway surface 2d. A vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body member is integrally formed on the outer circumferential surface 2o of the outer ring 2. The vehicle body mounting flange 2e is provided with bolt holes for inserting fastening members (here, bolts) that fasten the vehicle body member to the outer ring 2.

[0065] A small-diameter step 3a having a smaller diameter than the outer end is formed at the inner end of the outer peripheral surface 3o of the hub wheel 3. A shoulder 3e is formed at the outer end of the small-diameter step 3a of the hub wheel 3.

[0066] A wheel mounting flange 3b for mounting a wheel is integrally formed on the outer end of the hub 3. A plurality of bolt holes 3f are formed in the wheel mounting flange 3b. Hub bolts 3i for fastening the hub 3 to the wheel or brake components can be press-fitted into the bolt holes 3f.

[0067] An inner raceway surface 3c is provided on the outer circumferential surface 3o of the hub 3, facing the outer raceway surface 2d on the outer side of the outer ring 2. In other words, the hub 3 forms the inner raceway surface 3c on the outer side of the inner member. A sealing area 3d is formed at the base of the wheel mounting flange 3b of the hub 3, with which the sealing lip of the outer seal member 10 slides.

[0068] An inner ring 4 is provided on the small-diameter step 3a of the hub wheel 3. The inner ring 4 is fixed to the small-diameter step 3a of the hub wheel 3 by press-fitting and caulking. The inner ring 4 applies preload to the inner ball row 5 and the outer ball row 6 as rolling elements.

[0069] The inner ring 4 has an inner end face 4b at its inner end and an outer end face 4c at its outer end. The inner end face 4b is an example of an end face of the inner ring located on one side in the axial direction of the inner ring.

[0070] A caulking portion 3h is formed at the inner end portion of the small-diameter step portion 3a of the hub wheel 3. The caulking portion 3h is caulked to the inner end surface 4b of the inner ring 4. The inner ring 4 is fixed in the axial direction by the caulking portion 3h.

[0071] The caulking portion 3h is formed by plastically deforming the inner end portion of the small-diameter step 3a in the axial direction toward the outer diameter. The caulking portion 3h of the hub wheel 3 is in planar contact with the inner end surface 4b of the inner ring 4 in the axial direction.

[0072] An inner raceway surface 4a is provided on an outer circumferential surface 4o of the inner race 4 so as to face the inner outer raceway surface 2c of the outer race 2. In other words, the inner race 4 forms the inner raceway surface 4a on the inner side of the inner member.

[0073] The inner ball row 5 and the outer ball row 6 as rolling rows are formed by retaining a plurality of balls 7 as rolling elements in a cage 8 .

[0074] The inner ball row 5 is freely rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the inner outer raceway surface 2c of the outer ring 2. The outer ball row 6 is freely rollably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer outer raceway surface 2d of the outer ring 2. In other words, the inner ball row 5 and the outer ball row 6 are freely rollably accommodated between the two raceway surfaces of the outer and inner members.

[0075] In the wheel bearing device 1, a multi-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 multi-row tapered roller bearing instead of a multi-row angular contact ball bearing.

[0076] [Structure of the rivet joint between the inner ring and the hub]

[0077] like Figure 2 As shown, the inner ring 4 has an inner circumferential surface 4d parallel to the axial direction and an inner diameter chamfered portion 4f connecting the inner circumferential surface 4d to the inner end surface 4b. The inner diameter chamfered portion 4f increases in diameter as it approaches the inner side. The inner circumferential surface 4d of the inner ring 4 is an example of the inner circumferential surface of the inner ring.

[0078] The outer circumferential surface 4o of the inner ring 4 has a straight surface 4e parallel to the axial direction. The straight surface 4e is located inside the inner raceway surface 4a and at the inner end of the outer circumferential surface 4o. The inner circumference of the inner seal member 9 is fitted onto the straight surface 4e of the inner ring 4.

[0079] The inner ring 4 has an outer diameter chamfered portion 4g connecting a straight surface 4e and an inner end surface 4b. The straight surface 4e is located adjacent to the outer diameter chamfered portion 4g. The outer diameter chamfered portion 4g decreases in diameter as it approaches the inner side.

[0080] The outer diameter chamfered portion 4g is formed by cutting a portion of the inner ring 4 corresponding to the outer diameter chamfered portion 4g, then performing heat treatment, and then performing further cutting after the heat treatment. In other words, the outer diameter chamfered portion 4g is a re-cut surface that has been cut after the heat treatment.

[0081] The hub 3 is surface-hardened by high-frequency quenching or the like from the base of the wheel mounting flange 3b to the axially intermediate portion of the outer inner raceway surface 3c and the small-diameter step 3a.

[0082] Therefore, a hardened layer is formed on the surface of the hub wheel 3 from the base of the wheel mounting flange 3b to the inner raceway surface 3c on the outer side and the midway portion of the small-diameter step 3a in the axial direction.

[0083] On the other hand, the rivet portion 3h ( Figure 2 The hatched portion (in the figure) becomes an unquenched portion that is not subjected to quenching. In other words, the rivet portion 3h maintains the hardness of the blank surface after forging.

[0084] The rivet portion 3h of the hub ring 3 has a first outer peripheral surface 32 that faces the inner peripheral surface 4d of the inner ring 4, a second outer peripheral surface 33 that faces the inner diameter chamfered portion 4f of the inner ring 4, and a third outer peripheral surface 34 that faces the inner side end surface 4b of the inner ring 4. The first outer peripheral surface 32 is an example of the outer peripheral surface of the rivet portion that faces the inner peripheral surface of the inner ring.

[0085] The first outer peripheral surface 32 of the caulking portion 3h has an annular groove 31 that is recessed radially inward and radially separated from the inner peripheral surface 4d of the inner ring 4. The annular groove 31 is formed along the circumferential direction and is formed over the entire circumference of the first outer peripheral surface 32.

[0086] The portion of the first outer peripheral surface 32 other than the annular groove 31 contacts the inner peripheral surface 4d of the inner ring 4. The second outer peripheral surface 33 contacts the inner diameter chamfered portion 4f of the inner ring 4. The third outer peripheral surface 34 contacts the inner end surface 4b of the inner ring 4.

[0087] [Small diameter step before rivet formation in the hub]

[0088] like Figure 3 、 Figure 4 As shown, in the hub wheel 3 , the small-diameter step portion 3 a before the caulking portion 3 h is formed extends inwardly beyond the inner end surface 4 b of the inner ring 4 .

[0089] An annular groove 30 is formed on the outer peripheral surface of the small-diameter step portion 3a before the caulking portion 3h is formed. The annular groove 30 is formed along the circumferential direction and is formed over the entire circumference of the outer peripheral surface of the small-diameter step portion 3a.

[0090] The annular groove 30 has an outer end P1 and an inner end P2 in the axial direction.

[0091] The outer end P1 of the annular groove 30 is located axially outward of the boundary P3 between the inner circumferential surface 4d and the inner diameter chamfered portion 4f of the inner ring 4. Furthermore, the inner end P2 of the annular groove 30 is located axially inward of the boundary P3. In other words, the annular groove 30 is located axially across the inner circumferential surface 4d and the inner diameter chamfered portion 4f of the inner ring 4.

[0092] [Effect of the annular groove in the rivet]

[0093] The caulking portion 3h is formed by plastically deforming the inner end of the small-diameter step 3a, which has the annular groove 30, toward the outer diameter. The small-diameter step 3a has the annular groove 30 before the caulking portion 3h is formed, and the caulking portion 3h forms an annular groove 31 that is separated from the inner ring 4.

[0094] When the inner side end portion of the small-diameter step portion 3a is plastically deformed toward the outer diameter side to form the rivet portion 3h, circumferential stress is generated in the inner ring 4. However, since the rivet portion 3h has an annular groove 31 radially separated from the inner ring 4, the load applied to the inner ring 4 can be suppressed and the circumferential stress generated in the inner ring 4 can be reduced.

[0095] As a result, the amount of expansion of the inner ring 4 toward the outer diameter side caused by riveting the small-diameter step portion 3a is reduced, which can suppress the dimensional change of the inner raceway surface and improve the clearance accuracy between the inner raceway surface of the inner ring and the rolling element, thereby achieving a long life of the wheel bearing device.

[0096] Furthermore, by reducing the circumferential stress generated in the inner ring 4 , even when the outer diameter chamfered portion 4 g of the inner ring 4 is damaged by impact, the occurrence of cracks due to the circumferential stress generated in the inner ring 4 can be suppressed.

[0097] In this case, the groove depth d in the radial direction of the annular groove 30 formed in the small-diameter step portion 3a is preferably set to 0.2 mm to 0.9 mm.

[0098] This is because if the groove depth d of the annular groove 30 exceeds 0.9 mm, stress concentration may occur at a portion of the inner ring 4 corresponding to the end of the annular groove 31 formed in the caulking portion 3h, potentially causing cracks in the inner ring 4. Furthermore, if the groove depth d of the annular groove 30 is less than 0.2 mm, the annular groove 31 is not formed when the caulking portion 3h is formed, making it difficult to effectively reduce the circumferential stress.

[0099] In addition, the outer side end P1 of the annular groove 30 in the small diameter step portion 3a before the rivet portion 3h is formed is located at a position closer to the outside than the boundary point P3 of the inner ring 4. Therefore, when the small diameter step portion 3a is plastically deformed to form the rivet portion 3h, the annular groove 31 can be formed at a position opposite to the inner circumferential surface 4d of the inner ring 4.

[0100] By forming the annular groove 31 at a position facing the inner circumferential surface 4 d of the inner ring 4 in this manner, the load applied to the inner ring 4 can be effectively suppressed, and the circumferential stress generated in the inner ring 4 can be reduced.

[0101] In this embodiment, the annular groove 31 of the rivet portion 3h is opposed to the inner circumferential surface 4d of the inner ring 4 from its outer end to its inner end. However, a portion of the inner side may extend to the inner diameter chamfered portion 4f of the inner ring 4. In other words, the annular groove 31 may be formed across the inner circumferential surface 4d and the inner diameter chamfered portion 4f of the inner ring 4.

[0102] In addition, if Figure 4 As shown in the embodiment, the outer side end P1 of the annular groove 30 in the small diameter step portion 3a before the caulking portion 3h is formed is located on the outer side of the boundary point P3 of the inner ring 4, but as shown in FIG. Figure 5 As shown, the annular groove 30 can also be arranged so that the outer end P1 is axially located at the same position as the boundary point P3 of the inner ring 4. In the above case, when the small-diameter step 3a is caulked, the annular groove 31 is formed so that the caulked portion 3h is separated from the inner diameter chamfered portion 4f. Therefore, the annular groove 31 is formed so that the caulked portion 3h and the inner diameter chamfered portion 4f are separated in the radial and axial directions.

[0103] However, when the annular groove 30 is arranged so that the outer side end P1 is located closer to the inside than the boundary point P3 of the inner ring 4, it is difficult to form the annular groove 31 in the rivet portion 3h, and the effect of reducing the circumferential stress of the inner ring 4 cannot be expected, so it is not preferred.

[0104] [Stress distribution in the rivet and inner ring]

[0105] exist Figure 6 (a) shows the stress distribution in the caulking portion 3 h and the inner ring 4 when the caulking portion 3 h formed in the small-diameter step portion 3 a does not have the annular groove 31 .

[0106] exist Figure 6 In (a), due to the circumferential stress generated in the inner ring 4 , the stress distribution at the outer diameter chamfered portion 4 g of the inner ring 4 becomes high.

[0107] In this way, when the stress distribution of the outer diameter chamfered portion 4g of the inner ring 4 is high, if there is impact damage in the outer diameter chamfered portion 4g, stress concentration on the impact damage is promoted, and cracks starting from the impact damage may occur in the inner ring 4.

[0108] Furthermore, stress distribution is relatively high on the straight surface 4 e and the inner raceway surface 4 a of the inner ring 4 .

[0109] In this way, when the stress distribution of the straight surface 4e and the inner raceway surface 4a of the inner ring 4 is high, the size of the inner raceway surface 4a changes and the clearance accuracy between the inner raceway surface 4a of the inner ring 4 and the ball 7 decreases, and the sealing torque of the internal side sealing component 9 embedded in the straight surface 4e may change.

[0110] On the other hand, Figure 6 FIG. 1( b ) shows stress distribution in the caulking portion 3 h and the inner ring 4 when the caulking portion 3 h formed in the small-diameter step portion 3 a has the annular groove 31 as in the present embodiment.

[0111] When the rivet portion 3h has an annular groove 31, when the inner side end of the small-diameter step portion 3a is plastically deformed toward the outer diameter side, the load applied to the inner ring 4 is reduced by the action of the annular groove 31, and the circumferential stress generated in the inner ring 4 is reduced.

[0112] Therefore, in Figure 6 (b) shows the inner circle 4, with Figure 6 Compared to the case shown in (a) where the annular groove 31 is not formed in the caulking portion 3h, the stress distribution in the outer diameter chamfer 4g is lower. This reduces the risk of cracking caused by circumferential stress in the inner ring 4, even if the outer diameter chamfer 4g of the inner ring 4 is damaged by impact.

[0113] In addition, Figure 6 (b), with Figure 6 Compared to the case shown in (a) where the annular groove 31 is not formed in the caulking portion 3h, the stress distribution on the straight surface 4e and the inner raceway surface 4a of the inner ring 4 is lower.

[0114] In this way, if the stress distribution of the straight surface 4e and the inner raceway surface 4a of the inner ring 4 is suppressed to a lower level, the dimensional change of the inner raceway surface 4a becomes smaller, the clearance accuracy between the inner raceway surface 4a and the ball 7 is improved, and the sealing torque of the inner side sealing component 9 embedded in the straight surface 4e can be stabilized.

[0115] [Inner ring inner diameter chamfer]

[0116] like Figure 7 As shown, the inner diameter chamfered portion 4f of the inner ring 4 has an inner diameter tapered surface 41 and an inner diameter arcuate surface 42. The inner diameter tapered surface 41 extends from the axially inner end of the inner circumferential surface 4d of the inner ring 4 toward the inner side, which is one axial side. The inner diameter tapered surface 41 is located at the outer end of the inner diameter chamfered portion 4f.

[0117] The inner tapered surface 41 is inclined relative to the axial direction and increases in diameter toward the inner side. The inner tapered surface 41 is formed into a straight line when viewed from the circumferential direction. The inclination angle θ1 of the inner tapered surface 41 relative to the axial direction is set to be greater than 5 degrees and less than 25 degrees.

[0118] The inner diameter arc surface 42 is located between the inner diameter tapered surface 41 and the inner end surface 4b. The inner diameter tapered surface 41 and the inner end surface 4b are connected by the inner diameter arc surface 42. The inner diameter arc surface 42 increases in diameter as it approaches the inner side. When viewed from the circumferential direction, the inner diameter arc surface 42 is formed into an arc shape that is convex toward the inner diameter side.

[0119] Since the inner diameter chamfered portion 4f of the inner ring 4 has the inner diameter tapered surface 41 at the outer end, the amount of inner diameter chamfered portion 4f protruding toward the inner diameter side can be reduced compared to a case where the inner diameter chamfered portion 4f is formed entirely in an arc shape.

[0120] Therefore, when the small-diameter step portion 3a of the hub ring 3 is riveted to the inner ring 4, the inner ring 4 can be reliably fixed to the small-diameter step portion 3a, and the load applied to the inner ring 4 can be suppressed to an appropriate load, thereby reducing the circumferential stress generated in the inner ring 4.

[0121] It should be noted that if the inclination angle θ1 of the inner diameter tapered surface 41 is less than 5 degrees, the circumferential stress generated in the inner ring 4 may not be sufficiently reduced. On the other hand, if the inclination angle θ1 of the inner diameter tapered surface 41 is greater than 25 degrees, the stable fixation of the inner ring 4 to the small-diameter step 3a may be impaired. Therefore, the inclination angle θ1 of the inner diameter tapered surface 41 is preferably greater than 5 degrees and less than 25 degrees.

[0122] [Outer diameter chamfer of the inner ring]

[0123] like Figure 8 As shown, the outer diameter chamfered portion 4g of the inner ring 4 has an outer diameter tapered surface 43 and an outer diameter arcuate surface 44. The outer diameter tapered surface 43 extends from the axially inner end of the straight surface 4e of the inner ring 4 toward the inner side, which is one axial side. The outer diameter tapered surface 43 is located at the outer end of the outer diameter chamfered portion 4g.

[0124] The outer tapered surface 43 is inclined relative to the axial direction and decreases in diameter toward the inner side. The outer tapered surface 43 is formed into a straight line when viewed from the circumferential direction. The inclination angle θ2 of the outer tapered surface 43 relative to the axial direction is set to be greater than 10 degrees and less than 20 degrees.

[0125] The outer diameter arc surface 44 is located between the outer diameter tapered surface 43 and the inner side end surface 4b. The outer diameter tapered surface 43 and the inner side end surface 4b are connected by the outer diameter arc surface 44.

[0126] The outer diameter arc surface 44 decreases in diameter as it approaches the inner side. The outer diameter arc surface 44 is formed into an arc shape that is convex toward the outer diameter side when viewed from the circumferential direction. The curvature radius R of the outer diameter arc surface 44 is set to be greater than or equal to 1.0 mm and less than or equal to 2.0 mm.

[0127] Since the outer diameter chamfered portion 4g of the inner ring 4 has the outer diameter tapered surface 43 at the outer end, the amount of outer diameter chamfered portion 4g protruding toward the outer diameter side can be reduced compared to a case where the outer diameter chamfered portion 4g is formed entirely in an arc shape.

[0128] Therefore, the weight of the inner ring 4 can be reduced, thereby achieving lightweight wheel bearing device 1. In addition, compared with the case where the outer diameter chamfered portion 4g is entirely formed into an arc shape, stress concentration generated in the outer diameter chamfered portion 4g can be alleviated, thereby suppressing cracks in the inner ring 4.

[0129] In addition, the outer diameter chamfered portion 4g has an outer diameter tapered surface 43, which can maintain the roundness of the internal side sealing component 9 that is engaged with the inner ring 4, stabilize the interference fit between the internal side sealing component 9 and the inner ring 4, and thus suppress the increase in torque of the wheel bearing device 1 caused by the internal side sealing component 9.

[0130] It should be noted that if the inclination angle θ2 of the outer diameter tapered surface 43 is less than 10 degrees, the wheel bearing device 1 may not be sufficiently lightweight. On the other hand, if the inclination angle θ2 of the outer diameter tapered surface 43 is greater than 20 degrees, the stress concentration generated in the outer diameter chamfered portion 4g may not be sufficiently alleviated. Therefore, the inclination angle θ2 of the outer diameter tapered surface 43 is preferably greater than 10 degrees and less than 20 degrees.

[0131] Furthermore, if the radius of curvature R of the outer diameter arc surface 44 is less than 1.0 mm, the stress concentration generated in the outer diameter chamfered portion 4g may not be sufficiently alleviated. On the other hand, if the radius of curvature R of the outer diameter arc surface 44 is greater than 2.0 mm, the range within which the outer diameter tapered surface 43 is formed in the outer diameter chamfered portion 4g becomes smaller, and the effect of forming the outer diameter tapered surface 43 may not be fully achieved. Therefore, the radius of curvature R of the outer diameter arc surface 44 is preferably greater than 1.0 mm and less than 2.0 mm.

[0132] [Relationship between the axial length of the straight surface of the inner ring and the radial length of the inner ring]

[0133] like Figure 9 As shown, the axial length of the straight surface 4e of the inner ring 4 is s. In addition, the radial length between the straight surface 4e and the inner peripheral surface 4d of the inner ring 4 is t.

[0134] In the inner ring 4, the axial length s of the straight surface 4e and the radial length t between the straight surface 4e and the inner circumferential surface 4d are set to satisfy the relationship 0.25≤(s / t)≤0.95. Furthermore, the axial length s of the straight surface 4e is set to be 3 mm to 11 mm.

[0135] In the inner ring 4, if the radial length t becomes smaller relative to the axial length s, the generated circumferential stress tends to increase. In addition, if the radial length t becomes larger relative to the axial length s, the weight of the wheel bearing device 1 tends to increase, and the fuel efficiency of the vehicle tends to decrease.

[0136] In particular, if (axial length s / radial length t) is greater than 0.95, the circumferential stress generated in the inner ring 4 increases significantly, and if (axial length s / radial length t) is less than 0.25, the weight of the wheel bearing device 1 increases significantly.

[0137] Therefore, by setting the axial length s and radial length t to satisfy the relationship 0.25 ≤ (s / t) ≤ 0.95, the circumferential stress generated in the inner ring 4 can be reduced, while suppressing an increase in the weight of the wheel bearing device 1. This allows the magnitude of the circumferential stress generated in the inner ring 4 to be optimized relative to the weight of the wheel bearing device 1.

[0138] In addition, in the inner ring 4, if the axial length s of the straight surface 4e becomes smaller, there is a tendency for the generated circumferential stress to increase. If the axial length s of the straight surface 4e becomes larger, there is a tendency for the weight of the wheel bearing device 1 to increase and the fuel efficiency of the vehicle to decrease.

[0139] In particular, if the axial length s is less than 3 mm, the generated hoop stress increases significantly, and if the axial length s exceeds 11 mm, the weight of the wheel bearing device 1 increases significantly.

[0140] Therefore, by setting the axial length s to a range of 3 mm to 11 mm, the circumferential stress generated in the inner ring 4 can be reduced, and an increase in the weight of the wheel bearing device 1 can be suppressed. This allows the circumferential stress generated in the inner ring 4 to be optimized relative to the weight of the wheel bearing device 1.

[0141] In addition, in this embodiment, although the wheel bearing device 1 for a driving wheel is described, the present invention is also applicable to a wheel bearing device for a driven wheel.

[0142] The above describes the embodiments of the present invention, but the present invention is not limited to such embodiments and is merely illustrative. Of course, it can 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 scope of the claims, and also includes the equivalent meanings and all changes in the scope described in the scope of the claims.

Claims

1. A wheel bearing device comprising: An outer member having a plurality of rows of outer track surfaces on its inner periphery; an inner member comprising a hub having an axially extending small-diameter step on its outer periphery and at least one inner ring press-fitted into the hub's small-diameter step, and having a plurality of rows of inner raceway surfaces facing the plurality of rows of outer raceway surfaces; and Multiple rows of rolling elements are accommodated between the two track surfaces of the outer member and the inner member in a rolling manner. The inner ring is fixed in the axial direction by a rivet portion formed by plastically deforming one end portion of the small-diameter step portion toward the outer diameter side. in, The inner ring has an inner ring inner circumferential surface, an end surface on one side of the inner ring in the axial direction, and an inner diameter chamfered portion connecting the inner ring inner circumferential surface and the end surface on one side of the inner ring and increasing in diameter toward one side in the axial direction. The caulking portion is an unquenched portion that has not been subjected to quenching, and has an annular groove separated from the inner ring.

2. The wheel bearing device according to claim 1, wherein: The rivet portion has an outer peripheral surface of the rivet portion facing the inner peripheral surface of the inner ring, The annular groove is formed on the outer peripheral surface of the rivet portion and is separated from the inner peripheral surface of the inner ring.

3. The wheel bearing device according to claim 1 or 2, wherein: The inner diameter chamfered portion includes an inner diameter tapered surface extending from the inner peripheral surface of the inner ring toward one side in the axial direction and an inner diameter arc surface located between the inner diameter tapered surface and the end surface of one side of the inner ring. The inclination angle of the inner diameter tapered surface with respect to the axial direction is greater than or equal to 5 degrees and less than or equal to 25 degrees.

4. The wheel bearing device according to claim 1 or 2, wherein: The inner ring has: an inner ring outer peripheral surface; and an outer diameter chamfered portion, which connects the inner ring outer peripheral surface with the end surface of one side of the inner ring and decreases in diameter as it approaches one side in the axial direction. The outer diameter chamfered portion includes: an outer diameter tapered surface extending from the outer peripheral surface of the inner ring in the axial direction; and an outer diameter arc surface located between the outer diameter tapered surface and the end surface of one side of the inner ring. The inclination angle of the outer diameter tapered surface with respect to the axial direction is greater than or equal to 10 degrees and less than or equal to 20 degrees, and the curvature radius of the outer diameter arc surface is greater than or equal to 1.0 mm and less than or equal to 2.0 mm.

5. The wheel bearing device according to claim 1 or 2, wherein: The outer peripheral surface of the inner ring has a straight surface located adjacent to the outer diameter chamfered portion and parallel to the axial direction, The axial length s of the straight surface is greater than or equal to 3 mm and less than or equal to 11 mm. The axial length s and the radial length t between the straight surface of the inner ring and the inner circumferential surface of the inner ring satisfy the relationship of 0.25≤(s / t)≤0.95.

Images