JP4743890B2 - Wheel bearing device - Google Patents

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 device, and more particularly to a wheel bearing device for improving durability of a hub wheel in a third generation structure in which an inner ring is press-fitted and fixed. It is about.

  There are wheel bearing devices for vehicles such as automobiles, one for driving wheels and one for driven wheels. Needless to say, the cost has been reduced, but the weight and size have been reduced to improve fuel efficiency. As a typical example of the conventional structure, a wheel bearing device for a driven wheel as shown in FIG. 4 is known.

  This wheel bearing device is referred to as a third generation, and includes a hub wheel 51, an inner ring 52, an outer ring 53, and double row rolling elements 54, 54. The hub wheel 51 integrally has a wheel mounting flange 55 for mounting a wheel (not shown) at one end thereof, an inner rolling surface 51a on the outer periphery, and a small diameter extending in the axial direction from the inner rolling surface 51a. A step portion 51b is formed. Further, hub bolts 56 for fixing the wheels are planted at the circumferentially equidistant positions of the wheel mounting flanges 55.

  An inner ring 52 having an inner rolling surface 52a formed on the outer periphery is press-fitted into the small diameter step portion 51b of the hub wheel 51. The inner ring 52 is prevented from coming off from the hub wheel 51 in the axial direction by a caulking portion 51c formed by plastically deforming the end portion of the small diameter step portion 51b of the hub wheel 51 radially outward. .

  The outer ring 53 integrally has a vehicle body mounting flange 53b for mounting to a suspension device (not shown), and double row outer rolling surfaces 53a and 53a are formed on the inner periphery. Between the double row outer rolling surfaces 53a, 53a and the inner rolling surfaces 51a, 52a facing these, double row rolling elements 54, 54 are accommodated so as to roll freely.

  The hub wheel 51 is integrally formed by forging a carbon steel material having a carbon content of 0.40 to 0.80% by weight, and a portion indicated by cross hatching, that is, a wheel mounting flange 55. The surface is hardened by induction quenching from the base portion to the inner rolling surface 51a and the small diameter step portion 51b. The caulking portion 51c is made as raw material surface hardness after forging. On the other hand, the inner ring 52 is made of high carbon steel such as high carbon chromium bearing steel such as SUJ2, and is hardened and hardened to the core.

As a result, a low-cost and sufficiently durable wheel bearing device can be realized, and the caulking portion 51c can be prevented from being damaged, such as a crack, and fixed to the hub wheel 51 by the caulking portion 51c. It is possible to prevent the diameter of the inner ring 52 from changing to an extent that causes a practical problem. And while reducing possibility that this inner ring | wheel 52 will be damaged with the fixing operation | work, a preload can be maintained to an appropriate value, and also cost reduction can be aimed at by reduction of a number of parts, parts processing, and an assembly man-hour.
JP-A-11-129703

  In such a conventional wheel bearing device, the force that greatly deforms the inner diameter of the inner ring 52 is prevented so as to affect the durability such as the preload and the rolling fatigue life accompanying the caulking work. be able to. On the other hand, the corner A at the abutting portion with the small end surface 52b of the inner ring 52, that is, the corner A between the shoulder 51d and the small diameter step 51b of the hub wheel 51 is simply enlarged as shown in FIG. It is formed by a circular arc surface (single R) having one curvature radius a. Here, in such a wheel bearing device whose cross-section has been reduced in order to reduce the weight, the length of the abutting portion with the small end surface 52b of the inner ring 52 in a constrained space in order to ensure the rigidity of the inner ring 52. It is necessary to increase X (contact area). However, when the length X of the abutting portion is increased, the corner A becomes excessively small and excessive stress is generated. Especially, when the bending moment is repeatedly applied to the wheel bearing device, the machine of the hub wheel 51 There is a risk that the mechanical strength is significantly reduced.

  Further, when the radius of curvature of a single R is increased in order to reduce the stress generated in the corner A, interference with the chamfered portion 52c of the inner ring 52 becomes a problem. The interference between the corner portion A and the chamfered portion 52c of the inner ring 52 induces misalignment, and the durability of the inner ring 52 may be reduced. Therefore, it is necessary to suppress dimensional variation as much as possible in the processing of the corner A. However, the regulation of the dimensional variation leads to an increase in manufacturing cost, and when the variation due to the heat treatment deformation is taken into consideration, the regulation of the dimensional variation naturally has a limit. It has been a problem to suppress the stress.

  The present invention has been made in view of such a conventional problem. In the third generation structure in which the inner ring is press-fitted and fixed to the small-diameter step portion of the hub wheel, the corner portion between the shoulder portion of the hub wheel and the small-diameter step portion is provided. An object of the present invention is to provide a wheel bearing device in which the stress generated in the tire is suppressed and the durability of the hub wheel is improved.

In order to achieve such an object, the invention according to claim 1 of the present invention includes an outer member integrally including a vehicle body mounting flange on the outer periphery, and a double row outer rolling surface formed on the inner periphery. A wheel mounting flange is integrally formed at one end, one inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a small diameter step extending in an axial direction from the inner rolling surface via a shoulder. A hub wheel formed with a portion, and the other inner rolling surface that is press-fitted into the small-diameter stepped portion until it comes into contact with the shoulder portion of the hub wheel and faces the outer rolling surface of the double row on the outer periphery. For a wheel provided with an inner member composed of a formed inner ring, and a double row rolling element that is rotatably accommodated between both rolling surfaces of the inner member and the outer member via a cage. in the bearing device, the corner portion of the shoulder portion and the cylindrical portion of the hub wheel, is a composite R comprising a plurality of radii of curvature, which With most of the outboard side arc tangent of the composite R leading to the shoulder portion, the most inboard side of the arc tangent is connected to the cylindrical portion.

Thus, in the third-generation wheel bearing device in which the inner ring is press-fitted into the small-diameter step until the inner ring comes into contact with the shoulder of the hub ring, the corner between the shoulder of the hub ring and the small-diameter step is It is composed of a composite R composed of a plurality of radii of curvature , and among these composite R, the tangent of the arc on the most outboard side is connected to the shoulder, and the tangent of the arc on the most inboard side is connected to the small diameter step part . Providing a bearing device for wheels that secures the contact area with the small end face of the inner ring in a constrained space to increase the rigidity of the inner ring and suppress the stress generated at the corners, thereby improving the durability of the hub ring. can do.

The wheel bearing device according to the present invention has a body mounting flange integrally on the outer periphery, an outer member having a double row outer raceway formed on the inner periphery, and a wheel mounting flange integrally on one end. And a hub wheel formed on the outer periphery with one inner rolling surface facing the double row outer rolling surface, and a small-diameter step portion extending in an axial direction from the inner rolling surface through a shoulder, and An inner member comprising an inner ring that is press-fitted into the small-diameter stepped portion until the shoulder portion of the hub wheel is abutted, and has an outer ring formed on the outer periphery that faces the outer rolling surface of the double row. In the wheel bearing device comprising a double row rolling element that is rotatably accommodated via a cage between both rolling surfaces of the inner member and the outer member, the shoulder portion of the hub wheel a corner portion between the cylindrical portion is constituted by a composite R comprising a plurality of radii of curvature, and most of these composite R Autobo With the side of the arc tangent leads to the shoulders, the most since the inboard side of the arc tangent is connected to the cylindrical portion, to secure the contact area between the inner ring of the small end face in constrained space It is possible to provide a wheel bearing device in which the rigidity of the inner ring is increased, the stress generated in the corner portion is suppressed, and the durability of the hub ring is improved.

  A vehicle body mounting flange is integrally formed on the outer periphery, an outer member having a double row outer rolling surface formed on the inner periphery, a wheel mounting flange is integrally formed on one end, and the double row outer rolling is formed on the outer periphery. One inner rolling surface facing the running surface, a hub wheel formed with a small-diameter stepped portion extending in the axial direction from the inner rolling surface via the shoulder portion, and a shoulder state of the hub wheel. An inner member comprising an inner ring that is press-fitted into the small-diameter step portion and is formed with the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and the inner member and the outer member In the wheel bearing device comprising a double row rolling element that is slidably accommodated between both rolling surfaces via a cage, the corners of the shoulder portion of the hub wheel and the small diameter step portion, It is composed of a composite R composed of a plurality of curvature radii b and c, and one curvature radius b is obtained when the corner is composed of a single R. Maximum curvature smaller than the radius a of the other of the curvature radius c of curvature greater than the radius a, b <is set to be the relationship of a <c.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention, and FIG. 2 is an enlarged view of a main part of FIG. In the following description, the side closer to the outer side of the vehicle when assembled to the vehicle is referred to as the outboard side (left side in the drawing), and the side closer to the center is referred to as the inboard side (right side in the drawing).

  This wheel bearing device has a third generation structure on the side of the drive wheel, and the inner member 1, outer member 10, and double row rolling elements (balls) accommodated between the members 1 and 10 so as to roll freely. 6 and 6. The inner member 1 includes a hub ring 2 and an inner ring 3 that is press-fitted into the hub ring 2 through a predetermined scissors.

  The hub wheel 2 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end portion on the outboard side, and is used for fixing the wheel at a circumferentially equidistant position of the wheel mounting flange 4. Hub bolts 5 are planted. Further, one (outboard side) inner rolling surface 2a and a cylindrical small-diameter step portion 2b extending in the axial direction from the inner rolling surface 2a via the shoulder portion 2d are formed on the outer periphery of the hub wheel 2. ing. Then, the inner ring 3 on which the other (inboard side) inner raceway surface 3a is formed on the outer periphery is press-fitted into the small-diameter step portion 2b until it comes into contact with the shoulder portion 2d, and further, the end of the small-diameter step portion 2b. The inner ring 3 is fixed in the axial direction with respect to the hub wheel 2 in a state where a predetermined preload is applied to the bearing by a caulking portion 2c formed by plastically deforming the portion radially outward. As a result, a so-called self-retain structure that can maintain an appropriate bearing preload for a long period of time can be provided.

  The outer member 10 integrally has a vehicle body mounting flange 10b for mounting to a vehicle body (not shown) on the outer periphery, and a double row outer rolling surface 10a facing the inner rolling surfaces 2a and 3a on the inner periphery. 10a is integrally formed. And the double-row rolling elements 6 and 6 are accommodated between each rolling surface 10a, 2a and 10a, 3a, and are hold | maintained by the holder | retainers 7 and 7 so that rolling is possible. Further, seals 8 and 9 are attached to the end portion of the outer member 10 to prevent leakage of the lubricating grease sealed inside the bearing and intrusion of rainwater, dust and the like from the outside into the bearing.

  Outer member 10 is formed of medium carbon steel (carbon steel for SC system mechanical structure of JIS standard) containing carbon of 0.40 to 0.80% by weight such as S53C, and double row outer rolling surface 10a, 10a. Is hardened by induction hardening to a surface hardness of 58 to 64 HRC. Further, the inner ring 3 is made of high carbon chrome bearing steel made of SUJ2 or the like, and is hardened in the range of 58 to 64 HRC up to the core part by quenching.

  On the other hand, the hub wheel 2 is formed of medium carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, like the outer member 10, and includes the inner rolling surface 2a on the outboard side and the seal 8 A hardened layer 11 is formed in the range of 58 to 64 HRC by induction hardening over the seal land portion and the small-diameter step portion 2b in sliding contact with each other (indicated by cross hatching in the figure). The caulking portion 2c is an unquenched portion having a material surface hardness of 25 HRC or less after forging. Such an induction hardening pattern improves the strength of the hub wheel 2 and suppresses fretting wear on the fitting surface of the inner ring 3 to improve durability. Moreover, the workability of the caulking portion 2c can be improved, and the occurrence of cracks and the like due to plastic deformation can be prevented.

  Here, the corner portion B of the shoulder portion 2d and the small-diameter step portion 2b of the hub wheel 2 is formed of a composite R including a plurality of curvature radii b and c, as shown in an enlarged manner in FIG. In the present embodiment, the composite R is formed by grinding simultaneously with the inner rolling surface 2a and the shoulder 2d of the hub wheel 2 after the corner B is hardened by induction hardening. As a result, the corner B can be processed with high accuracy without being affected by the heat treatment deformation, and the bearing internal clearance (preload amount) can be regulated within a desired range.

  Of these composite Rs, one radius of curvature b is smaller than the maximum radius of curvature a when the corner portion B is formed of a single R as in the prior art, and the other radius of curvature c is larger than the radius of curvature a. Is also set large (b <a <c). As a result, the length of the abutting portion X with the small end surface 3b of the inner ring 3 can be ensured in a constrained space to increase the rigidity of the inner ring 3, and the stress generated at the corner B can be suppressed. 2 can improve the durability of the wheel bearing device. Further, in the processing of the corner portion B, interference with the chamfered portion 3c of the inner ring 3 can be prevented without suppressing dimensional variation more than necessary, and the cost can be reduced.

  Table 1 shows the results of analyzing the stress generated at the corners of the shoulder portion and the small diameter step portion of the hub wheel implemented by the present applicant. In the case of single R, the maximum curvature radius a = 3.5 mm, and the curvature radii b and c in the composite R are b = 2.5 mm and c = 8.2 mm in the first embodiment, and the second embodiment. Then, b = 2.0 mm and c = 7.6 mm. Further, there are two types of load conditions. In FIG. 1, the side surface of the vehicle body mounting flange 10b in the outer member 10 is a fixed surface, and the side surface of the wheel mounting flange 4 in the hub wheel 2 is a load loading surface. As apparent from Table 1, when the corners of the hub wheel shoulder and the small-diameter step portion are formed by a single R, the corner portion is formed by a composite R. The stress to be reduced can be reduced by 17-22%.

  Here, the wheel bearing device having a self-retained structure in which the small-diameter step portion 2b of the hub wheel 2 is oscillated and tightened is illustrated, but the wheel bearing device according to the present invention is not limited to such a structure. However, the inner ring may be simply press-fitted and fixed to the small-diameter step portion of the hub ring. In addition, although the double row angular contact ball bearing which used the rolling elements 6 and 6 as the ball | bowl was illustrated, it is not restricted to this, The double row tapered roller bearing which uses a tapered roller for a rolling element may be sufficient.

  FIG. 3 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. In this embodiment, the wheel bearing device according to the present invention is applied to the driven wheel side, and the same parts and portions having the same functions as those of the above-described embodiment are denoted by the same reference numerals and detailed description thereof is made. Description is omitted.

  This wheel bearing device is referred to as the third generation on the driven wheel side, and the inner member 12, the outer member 10, and the double row rolling elements 6 and 6 accommodated between the members 12 and 10 so as to roll freely. And. The inner member 12 includes a hub ring 13 and an inner ring 3 that is press-fitted into the hub ring 13 through a predetermined shimiro.

  The hub wheel 13 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end portion on the outboard side, an inner rolling surface 13a on the outer periphery, and an axial direction from the inner rolling surface 13a. A shaft-shaped small-diameter step portion 13b extending in the direction is formed. The inner ring 3 is axially inserted into the hub wheel 13 by a crimping portion 13c formed by press-fitting the inner ring 3 into the small-diameter step portion 13b and plastically deforming the end of the small-diameter step portion 13b radially outward. It prevents it from slipping out.

  The hub wheel 13 is made of medium carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and includes an inner rolling surface 13a on the outboard side, a seal land portion with which the seal 8 is in sliding contact, and a small diameter. The hardened layer 11 is formed in a range of 58 to 64 HRC by induction hardening over the stepped portion 13b (indicated by cross-hatching in the figure). The caulking portion 13c is an unquenched portion having a surface hardness of 25HRC or less after forging.

  Here, the corner portion B of the shoulder portion 2d of the hub wheel 13 and the small-diameter step portion 13b is formed of a composite R having a plurality of curvature radii, as in the above-described embodiment. As a result, it is possible to secure the contact area with the small end surface 3b of the inner ring 3 in a constrained space to increase the rigidity of the inner ring 3, and to suppress the stress generated at the corner B and to improve the durability of the hub ring 13. Can be improved.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  The wheel bearing device according to the present invention can be applied to a third-generation wheel bearing device in which an inner ring is press-fitted and fixed to a small-diameter step portion of a hub wheel.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is a principal part enlarged view same as the above. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus. It is a principal part enlarged view same as the above.

Explanation of symbols

1, 12 ... inner members 2, 13 ... hub wheels 2a, 3a, 13a ... inner rolling surfaces 2b, 13b ...・ ・ ・ ・ Small diameter step 2c, 13c ・ ・ ・ ・ ・ ・ ・ ・ Clamping part 2d ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shoulder 3 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・.... Inner ring 3b ... Small end face 3c ... Chamfered part 4 ... Wheel mounting flange 5... Hub bolt 6... Rolling element 7. ··································· Outer member 10a .... Body mounting flange 11 .... Hardened layer 51 ... .... Hub wheels 51a, 52a ... Inner rolling surface 51b ... Small diameter step 51c ... Clamping part 51d ... shoulder 52 ... inner ring 52b ... small end face 52c ... .... Chamfer 53 ... Outer ring 53a ... Outer rolling surface 53b ... Car body mounting Flange 54 ... Rolling element 55 ... Wheel mounting flange 56 ... Hub bolts A, B ... corners a, b, c ... ... radius of curvature X ... ... abutment section length

Claims (1)

An outer member (10) integrally having a vehicle body mounting flange (10b) on the outer periphery and having a double row outer rolling surface (10a) formed on the inner periphery;
One inner rolling surface (2a) which has a wheel mounting flange (4) integrally at one end and faces the double row outer rolling surface (10a) on the outer periphery, and this inner rolling surface (2a) The hub wheel (2) formed with a small-diameter step (2b) extending in the axial direction from the shoulder portion (2d) to the shoulder portion (2d) of the hub wheel (2) until the small diameter is reached. An inner member (1) composed of an inner ring (3) press-fitted into the stepped portion (2b) and formed with the other inner rolling surface (3a) opposed to the double row outer rolling surface (10a) on the outer periphery. )When,
Double row rolling elements (not shown) that are accommodated between the rolling surfaces (10a, 2a, 3a) of the inner member (1) and the outer member (10) via a cage (7). 6) a wheel bearing device comprising:
The corner of the shoulder of the hub wheel (2) and (2d) cylindrical portion and (2b) (B) is formed by a composite R comprising a plurality of radii of curvature (b, c), among these complex R The wheel bearing device, wherein the tangent of the arc on the most outboard side is connected to the shoulder (2d), and the tangent of the arc on the inboard side is connected to the small diameter step (2b) .

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