Wheel bearing device

Abstract

The purpose of this invention is to suppress occurrence of stick slip at a contact part between a hub wheel and a constant-velocity universal joint while maintaining strength of a caulking part in a wheel bearing device. A wheel bearing device 1 includes: an outer member (outer ring 2) having an outer raceway groove 2c·2d; an inner member which comprises a hub ring 3 and an inner ring 4 provided in a small-diameter step part 3a of the hub ring 3, in which a caulking part 3h is formed at an inner-side end part of the small-diameter step part 3a to integrate the hub ring 3 and the inner ring 4, and which has an inner raceway groove 3c·4a; rolling elements (balls 7) accommodated between the outer raceway groove 2c·2d and the inner raceway groove 3c·4a; and a constant-velocity universal joint 20 connected to the hub ring 3. The hub ring 3 has a flat part 3i abutting on an outer-side end surface of a shoulder part 23 of the constant-velocity universal joint 20, the flat part 3i protrudes from an inner-side end part of the caulking part 3h to the inner side, and the outer diameter of the flat part 3i is positioned radially inside of the inner diameter of the inner ring 4.

Description

Wheel bearing device

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

[0002] A known wheel bearing device for rotatably supporting a wheel in a suspension system for an automobile, etc., includes an outer member having double-row outer raceway grooves on its inner circumference, a hub wheel having a small-diameter stepped portion at the inner end of its outer circumference, and an inner ring provided on the small-diameter stepped portion of the hub wheel, the hub wheel and the inner ring being integrated by crimping the inner end of the small-diameter stepped portion of the hub wheel, an inner member having double-row inner raceway grooves facing the double-row outer raceway grooves, double-row rolling elements accommodated in a rollable manner between the raceway grooves of the outer member and the inner member, and a constant velocity universal joint connected to the hub wheel.

[0003] The constant velocity universal joint is provided at one end of an intermediate shaft constituting a drive shaft and includes an outer joint member, an inner joint member having track grooves formed on its outer peripheral surface that face the track grooves of the outer joint member, and balls inserted between the track grooves of the outer joint member and the track grooves of the inner joint member. The outer joint member of the constant velocity universal joint includes a shoulder portion that forms the bottom of a cup-shaped mouth portion and a shaft portion extending axially from the shoulder portion. The shaft portion of the outer joint member of the constant velocity universal joint is inserted into the axial hole of the hub wheel, and splines of the shaft portion of the outer joint member are engaged with splines of the hub wheel. Furthermore, with the shoulder portion of the constant velocity universal joint abutting against the crimped portion of the hub wheel, a fixing nut is fastened with a predetermined tightening torque to the male thread of the shaft portion of the outer joint member, allowing torque from the drive shaft to be transmitted to the hub wheel via the outer joint member.

[0004] Here, in the wheel bearing device, the relative amount of slippage at the abutting portion between the crimped portion of the hub wheel and the shoulder of the constant velocity universal joint may increase, resulting in stick-slip. To suppress such stick-slip, a known wheel bearing device has a configuration in which the crimped portion of the hub wheel is turned to form a flat surface, and the shoulder of the constant velocity universal joint is abutted against the flat surface of the hub wheel. In this way, by abutting the shoulder of the constant velocity universal joint against the flat surface of the hub wheel, the surface pressure at the abutting portion between the crimped portion of the hub wheel and the shoulder of the constant velocity universal joint is reduced, suppressing stick-slip.

[0005] Furthermore, in wheel bearing devices in which a flat surface is formed at the crimped portion of the hub wheel, the flat surface is formed by turning the crimped portion after the crimped portion of the hub wheel is formed, which can make the manufacturing process complicated.To eliminate this complicated manufacturing process, a wheel bearing device is known in which the abutment portion between the hub wheel and the shoulder of the constant velocity universal joint is positioned radially inward of the crimped portion of the hub wheel, and an axial gap is provided between the crimped portion of the hub wheel and the shoulder of the constant velocity universal joint (see Patent Document 1).

[0006] Japanese Patent Application Laid-Open No. 2007-326451

[0007] However, in the wheel bearing device of Patent Document 1, the abutment portion between the hub wheel and the shoulder of the constant velocity universal joint is located radially inward of the crimped portion. In this way, the crimped portion of the hub wheel is small, and a space for arranging the flat surface is formed on the inner diameter side of the crimped portion, which could result in insufficient strength of the crimped portion. Furthermore, depending on the design of the wheel bearing device, the structure of Patent Document 1 may not be applicable from the perspective of ensuring the strength of the crimped portion of the hub wheel. Furthermore, when a flat surface is provided at a position that protrudes inward from the inner end of the crimped portion to ensure the strength of the crimped portion of the hub wheel, if at least a portion of the flat surface is located radially outward of the inner diameter of the inner ring, the relative amount of slippage at the contact portion between the flat surface and the constant velocity universal joint may be relatively large, resulting in stick-slip at the contact portion between the hub wheel and the constant velocity universal joint.

[0008] Therefore, an object of the present invention is to provide a wheel bearing device and a wheel bearing assembly that can prevent stick-slip from occurring at the contact portion between the hub wheel and the constant velocity universal joint while maintaining the strength of the crimped portion.

[0009] That is, the bearing comprises an outer member having double row outer raceway grooves on its inner circumference, a hub ring having a small diameter step portion at the inner end of its outer circumference, and an inner ring provided on the small diameter step portion of the hub ring, and the hub ring and the inner ring are integrated by crimping the inner end of the small diameter step portion of the hub ring to form a crimped portion, and the hub ring and the inner ring are integrated, and an inner member having double row inner raceway grooves facing the double row outer raceway grooves, and a double row rolling bearing housed in a rollable manner between the raceway grooves of the outer member and the inner member. A wheel bearing device comprising: a body; a constant velocity universal joint having a shoulder portion and an axle portion extending axially from the shoulder portion, the axle portion being inserted into an axle hole of the hub wheel to connect to the hub wheel; wherein the hub wheel has a flat portion that abuts against the outer end face of the shoulder portion of the constant velocity universal joint, the flat portion of the hub wheel protruding toward the inner side from the inner end portion of the crimped portion, and the outer diameter of the flat portion being positioned radially inward relative to the inner diameter of the inner ring.

[0010] The present invention has the following effects.

[0011] That is, according to the present invention, it is possible to prevent stick-slip from occurring at the contact portion between the hub wheel and the constant velocity universal joint while maintaining the strength of the crimped portion.

[0012] 1 is a cross-sectional view showing a wheel bearing device according to an embodiment of the present invention;

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0014] A wheel bearing device 1 shown in FIG. 1 is one embodiment of a wheel bearing device according to the present invention, and is used to rotatably support a wheel in a suspension system of a vehicle such as an automobile.

[0015] The wheel bearing device 1 has a configuration known as 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, two rolling rows of inner ball rows 5 and outer ball rows 6, an inner sealing member 9 and an outer sealing member 10, and a constant velocity universal joint 20.

[0016] Here, the inner side refers to the vehicle body side of the wheel support bearing device 1 when it is attached to the vehicle body, and the outer side refers to the wheel side of the wheel support bearing device 1 when it is attached to the vehicle body. Also, the axial direction refers to the direction along the rotation axis X of the wheel support bearing device 1, with one axial end side being the outer side and the other axial end side being the inner side.

[0017] As shown in Figure 1, an inner side opening 2a is formed at the inner side end of the outer ring 2, into which an inner side seal member 9 can be fitted. An outer side opening 2b is formed at the outer side end of the outer ring 2, into which an outer side seal member 10 can be fitted. An inner side outer raceway groove 2c and an outer side outer raceway groove 2d are formed on the inner circumferential surface of the outer ring 2.

[0018] A vehicle body mounting flange 2e 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 2e is provided with bolt holes 2f into which fastening members (here, bolts) for fastening the outer ring 2 to the vehicle body member are inserted.

[0019] The inner end of the outer peripheral surface 3g of the hub wheel 3 is formed with a small-diameter step 3a that is smaller in diameter than the outer end. A wheel mounting flange 3b for mounting a wheel is formed integrally with the outer end of the hub wheel 3. A plurality of bolt holes 3d are formed in the wheel mounting flange 3b. Hub bolts 3e are press-fitted into the bolt holes 3d to fasten the hub wheel 3 to a wheel or brake component. The wheel mounting flange 3b is an example of a hub flange that extends radially outward. A spline for transmitting torque is formed on the inner peripheral surface of the shaft hole 3f of the hub wheel 3.

[0020] An outer inner raceway groove 3c is provided on the outer peripheral surface 3g of the hub wheel 3 so as to face the outer outer raceway groove 2d of the outer ring 2. In other words, the inner raceway groove 3c is defined by the hub wheel 3 on the outer side of the inner member. The outer seal member 10 is fitted into the outer opening end of the annular space formed by the outer ring 2 and the hub wheel 3, and closes this outer opening end. The outer seal member 10 is an example of a sealing device.

[0021] The inner ring 4 is mounted on the small diameter step 3a of the hub ring 3. The inner ring 4 is press-fitted into the small diameter step 3a via a predetermined interference. The inner end of the small diameter step 3a of the hub ring 3 is then crimped to cause plastic deformation, thereby integrating the hub ring 3 and the inner ring 4 and preventing the inner ring 4 from slipping out of the hub ring 3 in the axial direction. The inner ring 4 applies preload to the inner ball row 5 and outer ball row 6, which form the rolling rows. An inner-side inner raceway groove 4a is formed on the outer peripheral surface of the inner ring 4 so as to face the inner-side outer raceway groove 2c of the outer ring 2. In other words, the inner ring 4 defines the inner raceway groove 4a on the inner side of the inner member.

[0022] 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, held in a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway groove 4a of the inner ring 4 and the inner-side outer raceway groove 2c of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway groove 3c of the hub ring 3 and the outer raceway groove 2d on the outer side 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 grooves of the outer member and the inner member. In the wheel bearing device 1, the outer ring 2, the hub ring 3 and the inner ring 4, the inner ball row 5, and the outer ball row 6 form a double-row angular contact ball bearing.

[0023] The constant velocity universal joint 20 is provided at one end of an intermediate shaft (not shown) that constitutes a drive shaft, and is connected to the hub wheel 3. The constant velocity universal joint 20 has an outer joint member 21, an inner joint member (not shown) having track grooves formed on its outer peripheral surface that face the track grooves of the outer joint member 21, and balls (not shown) incorporated between the track grooves of the outer joint member 21 and the track grooves of the inner joint member.

[0024] The outer joint member 21 has a shoulder portion 22 that forms the bottom of the cup-shaped mouth portion, and a shaft portion 23 that extends axially from the shoulder portion 22. The shoulder portion 22 and shaft portion 23 of the outer joint member 21 are formed integrally. Splines are formed on the outer periphery of the shaft portion 23 of the outer joint member 21, and male threads are formed at the ends of the splines. The shaft portion 23 of the outer joint member 21 is inserted into the axial hole 3f of the hub wheel 3, and the splines of the shaft portion 23 of the outer joint member 21 and the splines of the hub wheel 3 are engaged with each other. Furthermore, a fixing nut 11 is fastened to the male threads of the shaft portion 23 of the outer joint member 21 with a predetermined tightening torque, so that torque from the drive shaft can be transmitted to the hub wheel 3 via the outer joint member 21.

[0025] 1 or 2, the hub wheel 3 has a crimped portion 3h, a flat portion 3i, and a stepped portion 3j. The crimped portion 3h of the hub wheel 3 is formed by crimping the inner end of the small diameter stepped portion 3a of the hub wheel 3.

[0026] The flat portion 3i of the hub ring 3 is formed on the inner diameter side portion of the inner end surface of the crimped portion 3h. The flat portion 3i of the hub ring 3 is configured by being turned so that its inner side surface is flat. The flat portion 3i of the hub ring 3 abuts against the outer end surface of the shoulder portion 22 of the outer joint member 21. The flat portion 3i of the hub ring 3 is configured to protrude toward the inner side from the inner end portion of the crimped portion 3h. The flat portion 3i of the hub ring 3 (the outer diameter of the flat portion 3i) is located radially inward of the inner diameter of the inner ring 4.

[0027] In this way, the hub wheel 3 has a flat portion 3i that abuts against the outer end surface of the shoulder portion 22 of the outer joint member 21, and the flat portion 3i of the hub wheel 3 protrudes toward the inner side from the inner end portion of the crimped portion 3h, with the outer diameter of the flat portion 3i located radially inward of the inner diameter of the inner ring 4. Because the flat portion 3i of the hub wheel 3 protrudes toward the inner side from the inner end portion of the crimped portion 3h, the crimped portion 3h can be configured to a size that ensures sufficient strength. Furthermore, because the outer diameter of the flat portion 3i is located radially inward of the inner diameter of the inner ring 4, the relative amount of slippage at the abutting portion between the hub wheel 3 (flat portion 3i) and the constant velocity universal joint 20 (outer end surface of the shoulder portion 22) can be reduced compared to a hub wheel 3 in which the flat portion 3i (at least a part of the flat portion 3i) is located radially outward of the inner diameter of the inner ring 4. Therefore, it is possible to prevent stick-slip from occurring at the contact portion between the hub wheel 3 and the constant velocity universal joint 20 while maintaining the strength of the crimped portion 3h of the hub wheel 3.

[0028] The flat portion 3i of the hub ring 3 is formed as a surface that is approximately perpendicular to the axial direction. The flat portion 3i of the hub ring 3 is formed as a substantially annular shape centered on the rotation axis X. The radial width A of the flat portion 3i of the hub ring 3 is configured to be approximately the same value at any point in the circumferential direction. The radial width A of the flat portion 3i of the hub ring 3 (the width of the inner surface of the flat portion 3i) is configured to be 3 mm or more. This configuration makes it possible to prevent an increase in surface pressure at the contact surface between the hub ring 3 (flat portion 3) and the constant velocity universal joint 20 (the outer end surface of the shoulder portion 22), and to prevent stick-slip from occurring at the contact portion between the hub ring 3 and the constant velocity universal joint 20.

[0029] The surface of the flat portion 3i of the hub wheel 3 that abuts on the outer end surface of the shoulder portion 22 of the outer joint member 21 (the inner surface of the flat portion 3i) is configured at a perpendicular angle of 0.2 mm or less to the rotation axis X (axial direction). This configuration makes it possible to prevent localized high surface pressure at the abutting surface between the hub wheel 3 (flat portion 3) and the constant velocity universal joint 20 (outer end surface of the shoulder portion 22). Therefore, it is possible to prevent stick-slip from occurring at the abutting portion between the hub wheel 3 and the constant velocity universal joint 20.

[0030] The inner diameter (inner diameter edge) of the flat portion 3i of the hub wheel 3 is configured with a runout of 1.0 mm or less relative to the rotation axis X. Because the inner diameter of the flat portion 3i of the hub wheel 3 is configured with a relatively high degree of circularity in this way, it is possible to prevent localized high surface pressure at the contact surface between the hub wheel 3 (flat portion 3) and the constant velocity universal joint 20 (the outer end surface of the shoulder portion 22). This makes it possible to prevent stick-slip from occurring at the contact portion between the hub wheel 3 and the constant velocity universal joint 20.

[0031] The stepped portion 3j of the hub wheel 3 is formed by turning the outer diameter portion of the inner end of the crimped portion 3h (the portion outer diameter side than the flat portion 3i) so that it is recessed toward the outer side than the flat portion 3i. The stepped portion 3j of the hub wheel 3 is located adjacent to the flat portion 3i. The stepped portion 3j of the hub wheel 3 prevents burrs created by turning the crimped portion 3h of the hub wheel 3 from coming into contact with the constant velocity universal joint 20 (the outer end surface of the shoulder portion 22), preventing localized increases in surface pressure at the contact surface between the hub wheel 3 and the constant velocity universal joint 20. This makes it possible to prevent stick-slip from occurring at the contact portion between the hub wheel 3 and the constant velocity universal joint 20. Furthermore, since the step portion 3j of the hub wheel 3 is formed by turning on the outer diameter side of the flat portion 3i, the shape of the outer diameter side edge of the flat portion 3i can be adjusted, and variations in the surface pressure at the contact surface between the hub wheel 3 and the constant velocity universal joint 20 can be suppressed.

[0032] The depth B of the recess toward the outer side at the step portion 3j of the hub wheel 3 is set to 0.1 mm or more. This configuration more reliably prevents burrs created by turning the crimped portion 3h of the hub wheel 3 from coming into contact with the constant velocity universal joint 20 (the outer end surface of the shoulder portion 22), more reliably preventing localized increases in surface pressure at the contact surface between the hub wheel 3 and the constant velocity universal joint 20. This therefore more reliably prevents stick-slip from occurring at the contact portion between the hub wheel 3 and the constant velocity universal joint 20.

[0033] The depth B of the recess toward the outer side of the step 3j of the hub wheel 3 is set to 0.5 mm or less. By not making the step 3j of the hub wheel 3 deeper than necessary, the strength of the crimped portion 3h of the hub wheel 3 can be maintained and the step 3j of the hub wheel 3 can be prevented from being corroded and stuck due to the infiltration of muddy water or the like into the step 3j of the hub wheel 3.

[0034] Although a so-called third-generation wheel bearing device has been exemplified, the wheel bearing device according to the present invention is not limited to this structure and may, for example, be of a first- or second-generation structure in which a pair of inner rings are press-fitted into a small-diameter stepped portion of a hub ring. Also, although a double-row angular contact ball bearing with ball rows 5 and 6 as rolling elements has been exemplified, the present invention is not limited to this and may be a double-row tapered roller bearing using tapered rollers as rolling elements.

[0035] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely examples, and it goes without saying that the present invention can be embodied in various other forms without departing from the spirit 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.

[0036] The present invention can be used in a wheel bearing device.

[0037] REFERENCE SIGNS LIST 1 Wheel bearing device 2 Outer ring 2a Inner opening 2b Outer opening 2c (Inner) outer raceway groove 2d (Outer) outer raceway groove 3 Hub ring 3a Small diameter step portion 3b Wheel mounting flange 3c Inner raceway groove 3f Shaft hole 3h Crimped portion 3i Flat portion 3j Step portion 4 Inner ring 4a Inner raceway groove 5 Inner ball row 6 Outer ball row 20 Constant velocity universal joint 21 Outer joint member 22 Shoulder portion A Radial width of flat portion of hub ring B Depth of step portion of hub ring X Rotating shaft

Claims

1. A wheel bearing device comprising: an outer member having double row outer raceway grooves on its inner circumference; a hub ring having a small diameter step at an inner end of its outer circumference, and an inner ring provided on the small diameter step of the hub ring, wherein the inner end of the small diameter step of the hub ring is crimped to form a crimped portion to integrate the hub ring and the inner ring, an inner member having double row inner raceway grooves facing the double row outer raceway grooves; double row rolling elements accommodated in a rollable manner between the raceway grooves of the outer member and the inner member; and a constant velocity universal joint having a shoulder portion and a shaft portion extending axially from the shoulder portion, the shaft portion being inserted into a shaft hole of the hub ring to be connected to the hub ring, wherein the hub ring has a flat portion that abuts against the outer end face of the shoulder portion of the constant velocity universal joint, A wheel bearing device, wherein the flat portion of the hub wheel protrudes toward the inner side from the inner end portion of the crimped portion, and the outer diameter of the flat portion is positioned radially inward relative to the inner diameter of the inner ring.

2. The wheel bearing device according to claim 1, wherein the flat portion of the hub wheel has a radial width of 3 mm or more.

3. A wheel bearing device as set forth in claim 1, wherein the surface of the flat portion of the hub wheel that abuts against the outer end surface of the shoulder portion of the constant velocity universal joint is configured at a perpendicular angle of 0.2 mm or less with respect to the axial direction.

4. A wheel bearing device as set forth in claim 1, wherein the inner diameter of the flat portion of the hub ring is configured with a runout of 1.0 mm or less relative to the rotation axis.

5. A wheel bearing device as described in claim 1, wherein the hub wheel has a step portion at the inner end of the crimped portion which is recessed toward the outer side from the flat portion, and the depth of the step portion of the hub wheel recessed toward the outer side from the flat portion is 0.1 mm or more.

6. A wheel bearing device as set forth in claim 5, wherein the depth of the step portion of the hub wheel recessed toward the outer side is 0.5 mm or less.

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