JP2023039458A - Wheel bearing device - Google Patents

Abstract

To provide a wheel bearing device which can make an inside rolling face of an inner ring possess two different curvature radii without applying special processing to the inside rolling face of the inner ring.SOLUTION: A step thin-thickness part 5b which is recessed to a large-diameter side is arranged at an inner side of an inside diameter face of an inner ring 5, a caulking part 4c which is obtained by elastically deforming an end part of a small-diameter step part 4b of a hub ring 4 to the outside of a radial direction is fit to the step thin-thickness part 5b, and an inside rolling face 5a of the inner ring 5 is made to possess two different curvature radii by curving the large-diameter side of the inside rolling face 5a of the inner ring 5 so as to have a curvature radius R2 which is larger than a curvature radius R1 at a small-diameter side when retaining the inner ring 5 to the small-diameter step part 4b of the hub ring 4.SELECTED DRAWING: Figure 3

Description

The present invention relates to a wheel bearing device for rotatably supporting a wheel of an automobile or the like with respect to a suspension system, and in particular, a wheel designed to improve durability by securing appropriate bearing preload and rigidity according to the traveling conditions of the vehicle. It relates to a bearing device for

Conventionally, as shown in FIGS. 5 and 6, there has been known a bearing device for a wheel that secures an appropriate preload when traveling straight and secures bearing rigidity when turning to improve durability. (Patent Document 1).

The one shown in FIG. 5 is what is called a third-generation wheel bearing device on the driven wheel side. An inner raceway surface is formed directly on the hub ring, and the other inner raceway surface is formed on a separate inner ring that is press-fitted into the hub ring.

The wheel bearing device shown in FIG. 5 includes an inner member 21, an outer member 22, and double-row balls 23, 23 which are housed between the members 21, 22 so as to be free to roll. The inner member 21 is composed of a hub wheel 24 and a separate inner ring 25 fitted on the hub wheel 24 . The hub wheel 24 integrally has a wheel mounting flange 26 at the end on the outboard side, and hub bolts 27 for fixing the wheel are implanted at equally distributed positions on the circumference of the wheel mounting flange 26 .

Further, an inner raceway surface 24a and a cylindrical small-diameter stepped portion 24b extending axially from the inner raceway surface 24a are formed on the outer periphery of the hub wheel 24. As shown in FIG. An inner ring 25 having an inner raceway surface 25a formed on its outer periphery is press-fitted into the small-diameter stepped portion 24b, and a caulking portion 24c is formed by plastically deforming the end portion of the small-diameter stepped portion 24b radially outward. As a result, the inner ring 25 is prevented from slipping out of the hub ring 24 in the axial direction.

The outer member 22 integrally has a vehicle body mounting flange 22b on its outer periphery, and double rows of outer raceway surfaces 22a, 22a are formed on its inner periphery. Between the rolling surfaces 22a, 24a and 22a, 25a, the double-row balls 23, 23 are freely rolled via retainers 28, 28 with a predetermined contact angle α shown in FIG. are housed in Sealing devices 29 and 30 are attached to the ends of the outer member 22 to prevent leakage of lubricating grease sealed inside the bearing and to prevent rainwater, dust, etc. from entering the bearing from the outside. are doing.

By the way, the inner ring 25 is preloaded so as to come into contact with the balls 23, 23 with a predetermined contact angle α. However, during turning, a moment load is applied to the bearings, and the preload in one row may be lost relative to the initial preload, and the surface pressure in the other row may become severe.
In order to solve this problem, as shown in FIG. 6 (FIG. 2 of Patent Document 1), when the vehicle is in steady running (straight ahead), the contact point P with the ball 23 at the initial contact angle α is a predetermined contact point P. Contact with the ball 23 at the contact angle α1 with a predetermined preload amount at the contact point P0 at the contact angle α1 when the vehicle is turning when a moment load is applied. It is disclosed that the inner raceway surface 25a of the inner ring 25 is formed in an arcuate shape having two curvature radii r and r1 in order to ensure proper preload and durability. That is, in Patent Document 1, the inner raceway surface 25a of the inner ring 25 has a curvature radius r formed from the vicinity of the contact point P at which the ball 23 contacts at the initial contact angle α to the groove bottom, and the contact angle α. and a radius of curvature r1 formed from the vicinity of the point to the large outer diameter.

JP 2010-138939 A

However, in FIG. 6, providing the inner raceway surface 25a of the inner ring 25 with two different radii of curvature increases the number of processing steps, and is difficult to actually implement in terms of cost.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a wheel bearing assembly capable of having two different radii of curvature in the state of the bearing assembly without subjecting the inner raceway surface of the inner ring to special processing or dimensional control. is.

The wheel bearing device of the present invention, which solves the above problems, comprises an outer member integrally formed with a double-row outer raceway surface on the inner circumference, and a double-row outer member on the outer circumference facing the double-row outer raceway surface. An inner member having rows of inner raceway surfaces formed thereon, and double-row balls housed between the raceway surfaces so as to be free to roll. The outer circumference of the hub wheel is formed with an inner raceway surface and a cylindrical small-diameter stepped portion extending axially from the inner raceway surface. is press-fitted into the small-diameter stepped portion, and the crimping portion formed by plastically deforming the end of the small-diameter stepped portion radially outward prevents the inner ring from slipping out of the hub wheel in the axial direction. In a wheel bearing device that prevents rolling, a thin stepped portion recessed toward the large diameter side is provided on the inner side of the inner diameter surface of the inner ring, and the caulking portion is fitted into the thin stepped portion, and the inner raceway surface of the outer circumference of the inner ring is provided. is given a larger radius of curvature R2 than the radius of curvature R1 of the smaller side.

The cylindrical small-diameter stepped portion axially extending from the inner raceway surface is composed of a hardened portion into which the inner ring is press-fitted and an unhardened portion forming the caulked portion. That is, the press-fit portion is quenched and the crimped portion is not heat treated.

The inner diameter of the step thin wall portion recessed toward the large diameter side provided on the inner side of the inner diameter surface of the inner ring is smaller than the outer diameter of the inner ring on the outer side. This is because if the inner diameter is too large, the amount of crimping must be increased, and the stress may damage the inner ring.

Further, the portion where the stepped thin wall portion of the inner ring and the inner diameter surface of the inner ring on the outer side are connected by the arc portion is located on the inner side from the extended line of the contact angle α. This is because if the arc portion is too far on the outboard side, the shape of R1 will be lost, and the target R cannot be obtained.

INDUSTRIAL APPLICABILITY As described above, the wheel bearing device according to the present invention is provided with a thin stepped portion recessed toward the large diameter side on the inner side of the inner diameter surface of the inner ring. When the inner ring is retained on the small-diameter stepped portion of the hub wheel by fitting the caulked portion that is plastically deformed radially outward, the large-diameter side of the inner raceway surface of the inner ring is less than the radius of curvature R1 of the small-diameter side. It is curved so as to have a large radius of curvature R2.

Therefore, the inner raceway surface of the outer circumference of the inner ring can be finished with a single radius of curvature R1. It can have a radius of curvature.

Further, by providing a stepped thin wall portion recessed toward the large diameter side on the inner side of the inner diameter surface of the inner ring, weight reduction can be achieved.

1 is a longitudinal sectional view showing an embodiment of a wheel bearing device of the present invention; FIG. FIG. 4 is a partially enlarged view showing a state before caulking the end of the small-diameter stepped portion of the hub wheel in the wheel bearing device of the present invention; FIG. 4 is a partial enlarged view showing the relationship between the balls and the inner raceway surface of the inner ring when the vehicle travels straight, after the end of the small-diameter stepped portion of the hub wheel in the wheel bearing device of the present invention has been crimped. FIG. 2 is a partially enlarged view showing the relationship between the balls and the inner raceway surface of the inner ring when a moment load is applied due to turning of the vehicle, after the end of the small-diameter stepped portion of the hub wheel in the wheel bearing device of the present invention is crimped; is. 1 is a longitudinal sectional view showing a conventional wheel bearing device; FIG. 6 is an enlarged view of an inner ring portion of the wheel bearing device of FIG. 5; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a wheel bearing device according to the present invention, FIG. 2 is a partially enlarged view showing a state before caulking the end of the small diameter stepped portion of the hub wheel, and FIG. Fig. 4 is a partially enlarged view showing the relationship between the balls and the inner raceway surface of the inner ring when the vehicle is traveling straight after the end of the small diameter stepped portion of the hub wheel has been crimped. FIG. 5 is a partial enlarged view showing the relationship between the balls and the inner raceway surface of the inner ring when a moment load is applied due to turning of the vehicle after crimping the ends.

In the following description, the side closer to the outside of the vehicle when assembled to the vehicle is called the outer side (left side in FIG. 1), and the side closer to the center is called the inner side (right side in FIG. 1).

The wheel bearing device of FIG. 1 is called the third generation on the driving wheel side, and includes an inner member 1 and an outer member 2, and double rows of balls 3 which are rotatably accommodated between the members 1 and 2. , 3. The inner member 1 is composed of a hub wheel 4 and a separate inner ring 5 fitted on the hub wheel 4 .

The hub wheel 4 integrally has a wheel mounting flange 6 for mounting a wheel (not shown) on the outer end thereof, and the wheels are fixed at the equidistant positions on the circumference of the wheel mounting flange 6. A hub bolt 7 is installed. Alternatively, wheel bolts may be used by forming threaded holes in the flange 6 instead of installing hub bolts.

The outer circumference of the hub wheel 4 is formed with an outer side (one) inner raceway surface 4a and a small-diameter stepped portion 4b extending axially from the inner raceway surface 4a. An inner ring 5 having an inner raceway surface 5a formed on its outer circumference is press-fitted into the small-diameter stepped portion 4b with a predetermined interference, and the end portion of the small-diameter stepped portion 4b is plastically deformed radially outward. The inner ring 5 is axially fixed to the hub wheel 4 with a predetermined bearing preload applied by the caulking portion 4c.

The outer member 2 integrally has a vehicle body mounting flange 2b for mounting to a vehicle body (not shown) on its outer periphery, and has a double-row outer raceway surface 2a facing the inner raceway surfaces 4a and 5a on its inner periphery. , 2a are integrally formed. Between the rolling surfaces 4a, 2a and 5a, 2a, the double rows of balls 3, 3 are freely rolled via the cages 8, 8 with the initial contact angle α shown in FIG. are housed in In addition, seals 9 and 10 are attached to the opening of the annular space formed between the inner member 1 and the outer member 2 to prevent leakage of lubricating grease enclosed inside the bearing and prevent external leakage. It prevents rainwater and dust from entering the bearing.

The inner ring 5 is provided with a step thin wall portion 5b recessed toward the large diameter side on the inner side of the inner diameter surface. The inner ring 5 is retained in the small-diameter stepped portion 4b of the hub wheel 4 by fitting the caulked portion 4c.

In order to form the caulked portion 4c, a cylindrical small-diameter stepped portion 4b extending axially from the inner raceway surface 4a forms a quenched portion into which the inner ring 5 is press-fitted and the caulked portion 4c. It consists of an unquenched part.

The outer side of the inner diameter surface of the inner ring 5 and the thin stepped portion 5b are connected by an arc portion 5c, which relieves stress concentration during crimping and fixing by the crimping portion 4c. The circular arc portion 5c of the step thin portion 5b of the inner ring 5 serves as a starting point when crimping the crimping portion 4c, and the large diameter side of the inner raceway surface 5a of the inner ring 5 has a curvature larger than the curvature radius R1 of the small diameter side. Bend to radius R2.

FIG. 2 shows a state before the inner side end of the small diameter stepped portion 4b of the hub wheel 4 is plastically deformed radially outward and crimped against the stepped thin portion 5b of the inner ring 5. A thin portion 4d is provided at the inner side end portion of the end portion of the small diameter step portion 4b of the hub wheel 4 so as to facilitate the formation of the caulking portion 4c.

The inner diameter of the stepped thin wall portion 5b recessed toward the large diameter side provided on the inner side of the inner diameter surface of the inner ring 5 is made smaller than the outer diameter of the inner ring 5 on the outer side. This is because if the inner diameter is too large, the amount of crimping must be increased, and the stress may damage the inner ring 5 .

Further, the portion where the thin stepped portion 5b of the inner ring 5 and the inner diameter surface of the inner ring 5 on the outer side are connected by the arc portion is located on the inner side from the extended line of the contact angle α. This is because if the arc portion is too far on the outboard side, the shape of R1 will be lost, and the target R cannot be obtained.

The inner raceway surface 5a on the outer periphery of the inner ring 5 has a single radius of curvature as shown in FIG. Finished with R1. This state is the state in which the ball 3 is given the initial contact angle α between the rolling surfaces 5a and 2a.

Then, as shown in FIG. 3, when the inner side end of the small diameter stepped portion 4b of the hub wheel 4 is plastically deformed radially outward and crimped against the stepped thin portion 5b of the inner ring 5, the Due to the caulking force, the large diameter side of the inner ring 5 is curved starting from the circular arc portion 5c of the stepped thin wall portion 5b, and the radius of curvature of a portion of the inner side of the inner raceway surface 5a of the large diameter side of the inner ring 5 is reduced to the original R1. The inner raceway surface 5a on the outer periphery of the inner ring 5 has the initial curvature radius R1 on the small diameter side (outer side) and the curvature radius R2 larger than R1 on the large diameter side (inner side). , that is, to have two different radii of curvature, R1<R2.

Since the inner ring 5 curves starting from the arc portion 5c of the thin stepped portion 5b, the thickness of the arc portion 5c of the thin stepped portion 5b is preferably at least 9 mm or more to maintain strength.

In this way, the inner raceway surface 5a on the outer periphery of the inner ring 5 has two different radii of curvature by caulking, and as shown in FIG. A preload is applied to the inner ring 5 so as to have a predetermined amount of preload at the contact point of R1.

Therefore, during normal running (straight running) of the vehicle, as shown in FIG. 3, the inner ring 5 and the ball 3 come into contact with each other at the portion of the radius of curvature R1 with a predetermined contact angle α.

When a moment load is applied due to turning of the vehicle, the contact angle becomes α1 as shown in FIG. Therefore, loss of preload is prevented, and durability can be maintained.

As described above, the inner raceway surface 5a on the outer circumference of the inner ring 5 is finished with a single radius of curvature before being crimped and fixed to the hub wheel 4, and by crimping and fixing to the hub wheel 4, the inner rolling surface 5a is Since two inner raceway surfaces 5a with different curvature radii are formed on the surface 5a, the inner raceway surfaces 5a with two different curvature radii can be formed without increasing the number of processing steps.

Further, since the inner ring 5 is provided with the stepped thin wall portion 5b recessed on the large diameter side, the weight of the inner ring 5 can be reduced by the amount of the stepped thin wall portion 5b.

The present invention is by no means limited to the above-described embodiments, and can of course be embodied in various forms without departing from the gist of the present invention. and includes equivalents and all changes within the scope of the claims.

1: Inner member 2: Outer member 2a: Outer raceway surface 3: Ball 4: Hub ring 4a: Inner raceway surface 4b: Small diameter stepped portion 4c: Crimp portion 4d: Thin portion 5: Inner ring 5a: Inner raceway Running surface 5b: Step thin portion 5c: Arc portion

Claims (5)

an outer member integrally formed with double-row outer raceway surfaces on its inner circumference, and an inner member with its outer circumference formed with double-row inner raceway surfaces opposed to the double-row outer raceway surfaces; The inner member comprises a hub ring and a separate inner ring externally fitted to the hub ring. An inner raceway surface and a cylindrical small-diameter stepped portion extending axially from the inner raceway surface are formed on the outer circumference, and an inner ring having an inner raceway surface formed on the outer circumference is press-fitted into the small-diameter stepped portion. A wheel bearing device in which the inner ring is prevented from slipping out of the hub wheel in the axial direction by a crimped portion formed by plastically deforming the end of the stepped portion radially outward, wherein the inner diameter surface of the inner ring A thin stepped portion recessed toward the large diameter side is provided on the inner side of the inner ring, the caulking portion is fitted into this thin stepped portion, and the large diameter side of the inner raceway surface of the outer circumference of the inner ring has a curvature larger than the curvature radius R1 of the small diameter side. A wheel bearing device characterized by having a radius R2. 2. The wheel bearing device according to claim 1, wherein the step thin portion of the inner ring and the inner diameter surface of the inner ring on the outer side are connected by an arc portion. 3. The cylindrical small-diameter step portion extending axially from the inner raceway surface comprises a hardened portion into which the inner ring is press-fitted and an unhardened portion forming the caulked portion. Wheel bearing device. 4. The wheel bearing according to any one of claims 1 to 3, wherein the inner diameter of the stepped thin wall portion recessed toward the large diameter side provided on the inner side of the inner diameter surface of the inner ring is smaller than the outer diameter of the inner ring outer side. Device. 5. The wheel according to any one of claims 1 to 4, wherein a portion where the stepped thin wall portion of the inner ring and the inner diameter surface on the outer side of the inner ring are connected by a circular arc portion is on the inner side from an extension line of the contact angle α. bearing device.

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