JP2024085273A - Wheel bearing device - Google Patents

Abstract

To provide a wheel bearing device which can improve the rigidity and a fatigue life of a caulking part.SOLUTION: A wheel bearing device 1 has an inner ring 4 axially fixed with: an outer ring 2 having outside raceway surfaces 2c, 2d; an inner member composed of a hub ring 3 having a small-diameter step part 3a and the inner ring 4 pressure-inserted into the small-diameter step part 3a, and having inside raceway surfaces 3c, 4a opposing the outside raceway surfaces 2c, 2d; double-row ball rows 5, 6 accommodated between both the raceway surfaces of the outer ring 2 and the inner member; and a caulking part 3h formed by plastic deformation of one end part of the small-diameter step part 3a in an axial direction to an outside-diameter side. In the wheel bearing device 1, the inner ring 4 has an internal peripheral face 4d, an inner-side end face 4b and a circular chamfered part 4e, and the small-diameter step part 3a has an annular groove 31 separated from the internal peripheral face 4d of the inner ring 4, and a third contact face 34 linearly contacting with the inner peripheral face 4d of the inner ring 4 along the axial direction between an inner-side end part P2 of the annular groove 31 and an outer-side end part P3 of the chamfered part 4e.SELECTED DRAWING: Figure 2

Description

The present invention relates to a wheel bearing device.

Wheel bearing devices that support the wheels rotatably in the suspension of an automobile or the like are known. Some wheel bearing devices have an inner ring press-fitted into a small diameter step of the hub wheel, which is the inner member, and the inner ring is fixed in the axial direction by a crimping portion formed by plastically deforming one end of the small diameter step toward the outer diameter side in the axial direction.

In this way, in wheel bearing devices in which the inner ring is fixed by forming a crimped portion on the hub wheel, the hoop stress generated in the inner ring is suppressed by forming an annular groove on the outer peripheral surface of the small diameter step before the crimped portion is formed, in the range from the portion facing the inner ring to the portion beyond one end face of the inner ring in the axial direction (see Patent Document 1).

JP 2007-218304 A

However, in a configuration in which an annular groove is formed near the portion of the outer circumferential surface of the hub wheel where the crimped portion is formed, stress may be concentrated at the crimped portion of the hub wheel, which may affect the strength and fatigue life of the crimped portion.

The present invention was made in consideration of the above circumstances, and provides a wheel bearing device that can improve the strength and fatigue life of the crimped portion in a configuration in which an annular groove exists in the small diameter step of the hub wheel where the crimped portion is formed.

That is, the wheel bearing device is composed of an outer member having a double-row outer raceway surface on its inner circumference, a hub wheel having a small diameter step extending in the axial direction on its outer circumference, and at least one inner ring press-fitted into the small diameter step of the hub wheel, and the inner member has a double-row inner raceway surface facing the double-row 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 crimping portion formed by plastically deforming one end of the small diameter step in the axial direction toward the outer diameter side, thereby forming the inner ring. A wheel bearing device in which a ring is fixed in the axial direction, the inner ring has an inner peripheral surface, one axial end face, and an arc-shaped chamfered portion connecting the inner peripheral surface and the one axial end face, and the small diameter step has an annular groove that is recessed from the outer peripheral surface toward the inner diameter side and is spaced apart from the inner peripheral surface of the inner ring in the radial direction, and a contact surface that makes linear contact with the inner peripheral surface of the inner ring along the axial direction between one end of the annular groove in the axial direction and the other end of the chamfered portion in the axial direction.

The present invention can improve the strength and fatigue life of the crimped portion in a wheel bearing device.

1 is a side cross-sectional view showing a wheel bearing device. 4 is a side cross-sectional view showing the vicinity of a crimped portion of a hub ring in a wheel bearing device. FIG.

Below, the embodiment of the present invention will be explained with reference to the attached drawings.

[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.

In the following description, the axial direction refers to the direction along the rotation axis X of the wheel bearing device 1. The inner side refers to one side in the axial direction, which is the vehicle body side of the wheel bearing device 1 when it is attached to the vehicle body, and the outer side refers to the other side in the axial direction, which is the wheel side of the wheel bearing device 1 when it is attached to the vehicle body.

The wheel bearing device 1 has a configuration called the third generation, and includes an outer ring 2 as the outer member, a hub wheel 3 and an inner ring 4 as the inner members, two rolling rows of inner ball rows 5 and outer ball rows 6, an outer seal member 9, and a cap 12.

An inner side opening 2a is formed at the inner side end of the outer ring 2 into which the cap 12 can be fitted. An outer side opening 2b is formed at the outer side end of the outer ring 2 into which the outer side seal member 9 can be fitted.

The annular space S inside the bearing is sealed by fitting an outer seal member 9 into the outer opening 2b, which is the outer opening end of the annular space S formed by the outer ring 2 and the hub wheel 3, and fitting a cap 12 into the inner opening 2a, which is the inner opening end of the annular space S.

The inner peripheral surface of the outer ring 2 is formed with an inner outer raceway surface 2c and an outer outer raceway surface 2d. The outer peripheral surface of the outer ring 2 is integrally formed with a vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body member. The vehicle body mounting flange 2e is provided with a bolt hole 2g into which a fastening member (here, a bolt) is inserted to fasten the vehicle body member and the outer ring 2.

The inner end of the hub wheel 3 has a small diameter step 3a formed on the outer circumferential surface, which is smaller in diameter than the outer end. A shoulder 3e is formed at the outer end of the small diameter step 3a of the hub wheel 3. A wheel mounting flange 3b for mounting a wheel is integrally formed at the outer end of the hub wheel 3. A number of bolt holes 3f are formed in the wheel mounting flange 3b. Hub bolts 3i for fastening the hub wheel 3 to a wheel or a brake component can be press-fitted into the bolt holes 3f.

The outer peripheral surface of the hub wheel 3 is provided with an outer inner raceway surface 3c that faces the outer outer raceway surface 2d on the outer side of the outer ring 2. In other words, the inner raceway surface 3c is formed by the hub wheel 3 on the outer side of the inner member. The base side of the wheel mounting flange 3b of the hub wheel 3 is formed with a sliding surface 3d against which the seal lip 9a of the outer seal member 9 slides.

The inner ring 4 is provided on the small diameter step 3a of the hub ring 3. The inner ring 4 is fixed to the small diameter step 3a of the hub ring 3 by press fitting and crimping. The inner ring 4 applies preload to the inner ball row 5 and the outer ball row 6, which are the rolling rows. 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 of the hub ring 3 is formed with a crimped portion 3h that is crimped to the inner end face 4b of the inner ring 4. The inner ring 4 is fixed in the axial direction by the crimped portion 3h. The crimped portion 3h is formed by plastically deforming the inner end of the small diameter step portion 3a toward the outer diameter side. The crimped portion 3h of the hub ring 3 and the inner end face 4b of the inner ring 4 are in planar contact in the axial direction.

The outer peripheral surface of the inner ring 4 is provided with an inner side inner raceway surface 4a that faces the inner side outer raceway surface 2c of the outer ring 2. In other words, the inner side of the inner member is formed by the inner ring 4 as the inner raceway surface 4a.

The inner ball row 5 and the outer ball row 6, which are rolling rows, are formed by a plurality of balls 7, which are rolling bodies, held by a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the outer raceway surface 2c on the inner side of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer raceway surface 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 housed in a rollable manner between the raceway surfaces of the outer member and the inner member.

In the wheel bearing device 1, a double-row angular 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. Note that the wheel bearing device 1 may be formed as a double-row tapered roller bearing instead of a double-row angular ball bearing.

A support ring 10 formed with an L-shaped cross section is fitted to the inner end of the inner ring 4. The support ring 10 has a cylindrical portion 10a that is pressed into the outer diameter of the inner ring 4 and a standing portion 10b that extends radially outward from the cylindrical portion 10a, and a magnetic encoder 11 is integrally joined to the inner side of the standing portion 10b by vulcanization adhesion. The magnetic encoder 11 is made of synthetic rubber mixed with magnetic powder such as ferrite, and is magnetized with N poles and S poles alternately at equal pitch in the circumferential direction.

The support ring 10 is formed by pressing a ferromagnetic steel plate, such as a ferritic stainless steel plate (JIS standard SUS430 series, etc.) or a rust-proofed cold-rolled steel plate. This strengthens the magnetic output of the magnetic encoder 11, ensuring stable detection accuracy.

The cap 12 that fits into the inner opening 2a of the outer ring 2 is formed into a cup shape by pressing a non-magnetic austenitic stainless steel plate (JIS standard SUS304, etc.).

A rotational speed sensor 14 is disposed at a position facing the magnetic encoder 11 on the inner side of the cap 12. The rotational speed sensor 14 and the magnetic encoder 11 are disposed facing each other in the axial direction with a predetermined air gap (axial clearance) between them via the cap 12. The rotational speed sensor 14 detects the displacement of the magnetic encoder 11, making it possible to detect the rotational speed of the inner ring 4.

A sensor holder 15 is fitted to the inner end of the outer ring 2, which is located on the inner side of the cap 12. The sensor holder 15 is formed into a cup shape by pressing a corrosion-resistant material, such as an austenitic stainless steel plate (JIS standard SUS304 type, etc.) or a rust-proofed cold-rolled steel plate (JIS standard SPCC type, etc.).

The sensor holder 15 has a support hole 15a into which the rotation speed sensor 14 is fitted. The rotation speed sensor 14 is supported by the sensor holder 15 by fitting the rotation speed sensor 14 into the support hole 15a.

[Configuration of press-fit portion of inner ring in small diameter step portion of hub ring]
2, the inner ring 4 has an inner peripheral surface 4d that faces the outer peripheral surface of the small diameter step portion 3a of the hub wheel 3, and an arc-shaped chamfered portion 4e that connects the inner peripheral surface 4d and the inner side end face 4b. The inner peripheral surface 4d of the inner ring 4 is formed to have the same diameter in the axial direction. In other words, the inner peripheral surface 4d of the inner ring 4 is formed parallel to the axial direction.

The outer peripheral surface of the small diameter step 3a of the hub wheel 3 into which the inner ring 4 is press-fitted has an annular groove 31, a first contact surface 32, a second contact surface 33, and a third contact surface 34. The annular groove 31 is recessed from the outer peripheral surface of the small diameter step 3a toward the inner diameter side, and is a surface spaced apart from the inner peripheral surface 4d of the inner ring 4 in the radial direction.

The annular groove 31 is formed in the circumferential direction and is formed around the entire outer circumferential surface of the small diameter step portion 3a. The annular groove 31 has an outer end P1 and an inner end P2 in the axial direction.

The first contact surface 32 is a surface located on the outer peripheral surface of the small diameter step portion 3a, which is located on the outer side of the outer end P1 of the annular groove 31, and is in contact with the inner peripheral surface 4d of the inner ring 4. The first contact surface 32 is in linear contact with the inner peripheral surface 4d of the inner ring 4 along the axial direction.

The second contact surface 33 is a surface located at the crimped portion 3h of the small diameter step portion 3a, and is in contact with the chamfered portion 4e of the inner ring 4. The second contact surface 33 is located on the inner side of the outer end P3 of the chamfered portion 4e in the axial direction.

The third contact surface 34 is a surface located on the outer peripheral surface of the small diameter step portion 3a between the inner end P2 of the annular groove 31 and the outer end P3 of the chamfered portion 4e, and is in contact with the inner peripheral surface 4d of the inner ring 4. The inner end P2 of the annular groove 31 is located on the outer side of the outer end P3 of the chamfered portion 4e.

The third contact surface 34 is in linear contact with the inner peripheral surface 4d of the inner ring 4 along the axial direction. The third contact surface 34 and the inner peripheral surface 4d of the inner ring 4 are in contact over the entire circumference in the circumferential direction. The third contact surface 34 is located on the inner side of the annular groove 31 in the axial direction.

The third contact surface 34 is an example of a contact surface that makes linear contact with the inner peripheral surface of the inner ring along the axial direction between one end of the annular groove in the axial direction and the other end of the chamfered portion in the axial direction.

The ball 7 in the inner ball row 5 is in contact with the inner raceway surface 4a of the inner ring 4 at the contact point 41, and the contact angle of the ball 7 in the inner ball row 5 with respect to the inner raceway surface 4a is α. The contact angle α is the inclination angle of the straight line connecting the center C of the ball 7 in the inner ball row 5 and the contact point 41 with respect to the radial direction.

A straight line L connecting the contact point 41 of the ball 7 with the inner raceway surface 4a of the inner ring 4 and the center C of the ball 7 intersects with the outer peripheral surface of the small diameter step 3a at an intersection P4. The intersection P4 is located in the annular groove 31 on the outer peripheral surface of the small diameter step 3a. The inner end P2 of the annular groove 31 is located on the inner side of the intersection P4 in the axial direction.

When bending stress is applied to the wheel bearing device 1, the inner ring 4 is pressed against the hub wheel 3. If the small diameter step 3a does not have the third contact surface 34 and the second contact surface 33 is located adjacent to the inner end P2 of the annular groove 31, the stress on the hub wheel 3 may be concentrated at the crimped portion 3h.

However, in the wheel bearing device 1, the small diameter step 3a of the hub wheel 3 has a third contact surface 34 that is in linear contact with the inner peripheral surface 4d of the inner ring 4 in the axial direction, so that the stress on the hub wheel 3 can be received not only by the crimped portion 3h but also by the third contact surface 34 located in the vicinity of the crimped portion 3h, making it possible to disperse and reduce the stress on the hub wheel 3.

This reduces the local stress on the hub wheel 3 and the stress amplitude, thereby improving the strength and fatigue life of the crimped portion 3h.

In particular, the inner end P2 of the annular groove 31 is located on the inner side of the intersection P4 of the straight line L with the outer circumferential surface of the small diameter step 3a, so that the stress applied to the hub wheel 3 can be effectively received by the third contact surface 34.

In addition, in the wheel bearing device 1, the radius R of the arc shape of the chamfered portion 4e of the inner ring 4 is set in the range of 1 mm or more and 5 mm or less.
If the radius R were smaller than 1 mm, the surface pressure at the chamfered portion 4e of the inner ring 4 that comes into contact with the crimped portion 3h of the hub wheel 3 would increase, and there is a risk of cracks occurring in the crimped portion 3h.

Furthermore, if the radius R is greater than 5 mm, the contact area between the crimped portion 3h of the hub wheel 3 and the inner end face 4b of the inner ring 4 will be small, and there is a risk that the axial force applied from the crimped portion 3h to the inner ring 4 will be insufficient.

Therefore, by setting the radius R of the chamfered portion 4e to a range of 1 mm or more and 5 mm or less, it is possible to improve the strength and fatigue life of the crimped portion 3h.

In this embodiment, the wheel bearing device 1 for a driven wheel is described, but the present invention can also be applied to a wheel bearing device for a driving wheel.

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.

Reference Signs List 1 Wheel bearing device 2 Outer ring 2a Inner opening 2b Outer opening 2c (Inner) outer raceway surface 2d (Outer) outer raceway surface 3 Hub ring 3a Small diameter step 3c (Hub ring) inner raceway surface 3h Crimped portion 4 Inner ring 4a (Inner ring) inner raceway surface 4b Inner end face 4d Inner circumferential surface 4e Chamfered portion 5 Inner ball row 6 Outer ball row 7 Ball 31 Annular groove 34 Third contact surface L Straight line C Center P2 (Annular groove) Inner end P3 (Chamfered portion) Outer end P4 Intersection R Radius of arc shape at chamfered portion

Claims (3)

an outer member having a double row outer raceway surface on an inner periphery thereof;
an inner member including a hub ring having an axially extending small diameter step on an outer periphery thereof and at least one inner ring press-fitted into the small diameter step of the hub ring, the inner member having a double row inner raceway surface facing the double row outer raceway surfaces;
a double row of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member;
a crimping portion formed by plastically deforming one end of the small diameter step portion in the axial direction toward an outer diameter side, the inner ring being fixed in the axial direction,
the inner ring has an inner circumferential surface, one end face in an axial direction, and an arc-shaped chamfered portion connecting the inner circumferential surface and the one end face in the axial direction,
The small diameter step portion is
an annular groove recessed from an outer peripheral surface to an inner diameter side and spaced apart from the inner peripheral surface of the inner ring in a radial direction;
a contact surface that linearly contacts the inner peripheral surface of the inner ring along the axial direction between one axial end of the annular groove and the other axial end of the chamfered portion. The one end of the annular groove in the axial direction is
2. The wheel bearing device according to claim 1, wherein the rolling element is located on one side in the axial direction of an intersection of a straight line connecting a contact point of the rolling element with the inner raceway surface of the inner ring and a center of the rolling element with the outer peripheral surface of the small diameter step portion. The wheel bearing device according to claim 1 or 2, wherein the radius of the arc shape of the chamfered portion is 1 mm or more and 5 mm or less.

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