JP2008168768A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent interference between a corner of a root of a wheel attaching flange and a base of a brake rotor, and to make the wheel attaching flange further thinner without increasing manufacturing cost. <P>SOLUTION: A corner of a root on an out board side to which the brake rotor 11 of the wheel attaching flange 3a is attached is formed by connecting a first R portion with a small curvature radius R1 rising from a body side, and a second R portion on a flange side having a larger curvature radius R2 and formed in a separating direction from the base of the brake rotor 11. The interference between the corner of the root of the wheel attaching flange 3a and the base of the brake rotor 11 is prevented, and the wheel attaching flange 3a is made to be further thinner without increasing manufacturing cost. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device in which a wheel mounting flange for mounting a wheel and a brake rotor is erected on either one of an outer member and an inner member.

  A wheel bearing device in which a wheel mounting flange for mounting a wheel serving as a driving wheel or a driven wheel and a brake rotor is erected on an outer member or an inner member serving as a hub wheel is a wheel mounting flange for the purpose of reducing the weight of an automobile. Thinning is being promoted. However, since the corner portion of the base of the wheel mounting flange on the side where the brake rotor is mounted is formed with an R portion having a small radius of curvature so that the base portion of the brake rotor does not interfere, the moment load applied to the wheel mounting flange The bending stress resulting from the above is concentrated, and this bending stress approaches the fatigue limit of the material, and it is difficult to make the wheel mounting flange thinner than this. The corner portion of the base on the opposite side of the brake rotor mounting side that does not interfere with the base of the brake rotor is, for example, a bearing portion like the inboard side of the inner member with a wheel mounting flange erected. Since the seal member is a seal land portion having a large radius of curvature with which the seal member slides, it does not hinder the thinning of the wheel mounting flange.

  As a means for overcoming the limit of thinning of the wheel mounting flange caused by the stress concentration at the corner of the base on the brake rotor mounting side as described above, the corner of the base on the outboard side of the wheel mounting flange to which the brake rotor is mounted can be used. It has been proposed to form a hardened surface layer on the part and increase the fatigue limit of the material of the corner part (see, for example, Patent Document 1).

JP 2002-87008 A

  The wheel bearing device described in Patent Document 1 increases the fatigue limit of the material without changing the size and shape so that the corner portion of the base of the wheel mounting flange does not interfere with the base portion of the brake rotor. Although it is possible to promote further thinning of the flange, since it is necessary to perform heat treatment such as induction hardening in order to form a hardened surface layer at the corner of the base, there is a problem that the manufacturing cost increases accordingly. .

  Accordingly, an object of the present invention is to prevent further interference between the corner portion of the base of the wheel mounting flange and the base portion of the brake rotor, and to promote further thinning of the wheel mounting flange without increasing the manufacturing cost. It is to be.

  In order to solve the above problems, the present invention has an outer member having a double row raceway surface on the inner diameter side and a double row raceway surface facing each raceway surface on the outer member on the outer diameter side. An inner member, and rolling elements arranged in a double row between the outer member and the raceway surface of the inner member, and either one of the outer member and the inner member includes a wheel and a brake. In the wheel bearing device in which the wheel mounting flange for mounting the rotor is erected, the corner portion of the base on the side of the wheel mounting flange on which the brake rotor is mounted is set to the first R portion on the main body side that rises from the main body side. Also, a configuration in which the second R portion on the flange side having a large radius of curvature was connected was adopted.

  As shown in a later embodiment, the inventors of the present invention have formed a corner portion at the base of the wheel mounting flange 3a on the brake rotor mounting side as a conventional R portion having a constant curvature radius R0 (FIG. 3). ) And a first R portion having a small curvature radius R1 rising from the main body side and a second R portion on the flange side having a larger curvature radius R2 connected thereto (FIG. 2), the wheel mounting flange 3a The stress generated in the vicinity of the corner of the root when an axial moment load was applied to was analyzed by the finite element method. The magnitude relationship between the radii of curvature is R1 <R0 <R2. As a result, as shown in FIGS. 4 (a) and 4 (b), the maximum stress is generated on the flange side of the corner portion of the base, and the R portion has a constant radius of curvature R0 (FIG. 4 ( It was found that the maximum stress is lower in the case where the radius of curvature R2 of the second R portion on the flange side is larger than the radius of curvature R1 (FIG. 4A) than in b)).

  Based on this analysis result, the corner portion of the base on the side where the brake rotor of the wheel mounting flange is attached has a radius of curvature larger than that of the first R portion on the main body side rising from the main body side, By connecting the second R part on the flange side formed in the direction of escaping from the base part, the interference between the corner part of the base of the wheel mounting flange and the base part of the brake rotor is prevented, and the manufacturing cost is reduced. It was possible to promote further thinning of the wheel mounting flange without increasing it.

  Even if the first R portion and the second R portion are smoothly connected via the third R portion or the straight portion, the maximum stress generated at the corner portion of the base of the wheel mounting flange can be reduced. it can.

  Even if the first R portion and the second R portion are connected so as to intersect with each other in a convex shape, the maximum stress generated in the corner portion at the base of the wheel mounting flange can be reduced.

  The radius of curvature of the second R portion on the flange side is at least twice, preferably at least three times the radius of curvature of the first R portion on the main body side.

  The corner portion of the root in which the first R portion and the second R portion are smoothly connected may be formed to have a dullness.

  The wheel bearing device of the present invention has a corner portion at the base of the wheel mounting flange on the side where the brake rotor is mounted, a first R portion on the main body side that rises from the main body side, and a radius of curvature larger than this, and the brake rotor Since the second R part on the flange side formed in the direction of escaping from the base part of the wheel is connected, the manufacturing cost is reduced after preventing interference between the corner part of the base of the wheel mounting flange and the base part of the brake rotor. Further thinning of the wheel mounting flange can be promoted without increasing the thickness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the wheel bearing device includes an outer member 1 having a double row raceway surface 2 on the inner diameter side, and a double row raceway surface 4 facing each raceway surface 2 of the outer member 1. It consists of an inner member 3 on the radial side and balls 5 as rolling elements arranged in a double row between these raceway surfaces 2, 4, and both sides of the bearing portion on which these balls 5 are arranged are sealed. Sealed by members 6a and 6b. The track surface 4 on the inboard side of the inner member 3 is provided on the outer diameter surface of a separate inner ring 7 fitted and fixed to the inner member 3.

  This wheel bearing device supports the driven wheel, the outer member 1 is fixed to the vehicle body side by a flange 1a, and the inner member 3 is a hub wheel that rotates, and a wheel mounting flange 3a is erected. The brake rotor 11 and a wheel (not shown) as a driven wheel are attached to the outboard side with a hub bolt 12. In addition, a seal land portion 3b having a large curvature radius with which the seal member 6a is slidably contacted is formed at a corner portion at the base on the inboard side of the wheel mounting flange 3a.

  As shown in FIG. 2, the corner portion of the base on the outboard side of the wheel mounting flange 3a has a first R portion having a radius of curvature R1 rising from the main body side and a radius of curvature R2 larger than this, and the brake A flange-side second R portion formed in a direction to escape from the base portion of the rotor 11 is connected.

  As an example, as shown in FIG. 2, the corner portion of the base on the outboard side of the wheel mounting flange 3a has a first R portion of a curvature radius R1 rising from the main body side and a curvature radius R2 larger than this. A model of the inner member 3 in which the second R portion on the flange side having the same is connected was prepared. In this example, R1 = 1.2 mm and R2 = 4 mm. As a comparative example, as shown in FIG. 3, a model of a conventional inner member 3 in which the corner portion of the base on the outboard side of the wheel mounting flange 3a is formed with an R portion having a constant curvature radius R0 (= 3 mm) is also available. Prepared. With respect to the models of these examples and comparative examples, the root of the base on the outboard side when the axial moment load (1.6 kN · m) is applied from the bearing portion with the mounting position of the hub bolt 12 fixed. The stress generated near the corner was analyzed by the finite element method.

  FIGS. 4A and 4B show screens obtained by performing image processing for each color of the stress distribution obtained by analysis by the finite element method for the models of the above-described examples and comparative examples. In either case, the red maximum stress portion is generated on the flange side of the corner portion of the base. However, in the embodiment shown in FIG. It is considerably narrower than that of the comparative example shown in b). Although it cannot be identified from the image-processed screen, the peak value of the maximum stress in the raw numerical data is 332 MPa in the comparative example, whereas it is 315 MPa in the example, and the peak value of the maximum stress is Is reduced by about 5%. Therefore, it is possible to promote further thinning of the wheel mounting flange 3a without increasing the manufacturing cost while preventing interference between the corner portion of the base and the base portion of the brake rotor 11.

  FIGS. 5A, 5B, and 5C show modifications of the corner portion of the base on the outboard side of the wheel mounting flange 3a. The modified example of FIG. 5A is obtained by smoothly connecting the first R portion and the second R portion via a straight line portion 3c, and the modified example of FIG. 5B has a curvature radius R1. The first R portion and the second R portion having the radius of curvature R2 are connected so as to intersect in a convex shape. Further, in the modified example of FIG. 5C, the corner portion of the root in which the first R portion and the second R portion are directly connected is formed into a shape having a dull 3d.

  In the above-described embodiment, the inner member is the hub wheel and the wheel mounting flange is erected and the brake rotor is attached to the outboard side. However, the wheel bearing device according to the present invention uses the outer member as the hub wheel. As described above, the present invention can be applied to a structure in which a wheel mounting flange is erected, and can also be applied to a structure in which a brake rotor is mounted on the inboard side of the wheel mounting flange.

A longitudinal sectional view showing an embodiment of a wheel bearing device Sectional drawing which expands and shows the corner part of the base on the outboard side of the wheel mounting flange of FIG. Sectional drawing which expands and shows the corner part of the base of the outboard side of the conventional wheel mounting flange a and b are image processing screens showing the results of analyzing the stress in the vicinity of the corner portion at the base of the models of the embodiment and the comparative example shown in FIGS. 2 and 3 by the finite element method, respectively. a, b, and c are cross-sectional views showing modifications of the corner portion of the base in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer member 1a Flange 2 Raceway surface 3 Inner member 3a Wheel mounting flange 3b Seal land part 3c Straight line part 3d Brace 4 Raceway surface 5 Ball 6a, 6b Seal member 7 Inner ring 11 Brake rotor 12 Hub bolt

Claims (5)

  An outer member having a double-row raceway surface on the inner diameter side, an inner member having a double-row raceway surface facing the raceway surface of the outer member on the outer diameter side, and the outer member and the inner member A wheel bearing comprising a rolling element arranged in a double row between the raceway surfaces of a member, and a wheel mounting flange for mounting a wheel and a brake rotor on one of the outer member and the inner member. In the apparatus, the corner portion of the base on the side where the brake rotor is to be mounted of the wheel mounting flange, the first R portion on the main body side rising from the main body side, and the second R on the flange side having a larger radius of curvature than this. A wheel bearing device characterized by connecting parts.   The wheel bearing device according to claim 1, wherein the first R portion and the second R portion are smoothly connected through a third R portion or a straight portion.   The wheel bearing device according to claim 1, wherein the first R portion and the second R portion are connected so as to intersect with each other in a convex shape.   4. The wheel bearing device according to claim 1, wherein a radius of curvature of the second R portion on the flange side is equal to or greater than twice a radius of curvature of the first R portion on the main body side.   The wheel bearing device according to any one of claims 1 to 4, wherein a corner portion of a root connecting the first R portion and the second R portion has a shape having a dullness.