JP2008114821A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel reduced in weight and size and manufacturable at low cost. <P>SOLUTION: This bearing device for a wheel has a structure referred to as a so-called the fourth generation which is formed by detachably unitizing a hub wheel 1, a double-row rolling bearing 2, and a constant velocity universal joint 3. A shaft part 1b extending in the axial direction is formed on the inner side of an inner side rolling surface 1a. A serration (or spline) is formed in the outer peripheral surface of the shaft part 1b. A male screw part 1c is formed on the inner side of the shaft part 1b. The bearing device has a cylindrical small-diameter step part 20 extending to the axial outer side of an inner rolling surface 14a. A serration (or spline) is formed in the inner peripheral surface of the small-diameter step part 20. After the hub wheel 1 is fitted to an outer side joint member 14, a nut 21 is tightened to the male screw part 1c of the hub wheel 1 to fix the outer side joint member 14 to the hub wheel 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device for supporting wheels of a vehicle such as an automobile.

  2. Description of the Related Art In recent years, a wheel bearing device that supports a wheel rotatably with respect to a suspension device of an automobile has been rapidly being unitized to increase rigidity for lighter weight for improving fuel efficiency and steering stability.

Patent Document 1 discloses such a unitized wheel bearing device. This example exemplifies a so-called expanded caulking type 4th generation hub joint in which the stem portion of the constant velocity joint is hollow, the inner diameter portion of the hub wheel is provided with irregularities, and the stem portion is expanded and tightened. In this example, a lightweight wheel bearing that achieves light weight and compactness, and has a sufficient strength at the plastic joint even when a large moment load is applied to the device, and the strength of the stem can be increased. An apparatus can be provided.
JP 2004-76872 A

  In the apparatus shown in Patent Document 1, since the stem portion of the constant velocity joint is encroached into the uneven portion of the inner diameter portion of the hub wheel, the stem portion is inserted in order to insert the enlarged punch used for expanding the diameter. Must have a hollow structure. However, in order to make the stem portion hollow, cutting is required, which leads to an increase in cost due to an increase in man-hours. Moreover, there is much waste from the viewpoint of material costs, which contributes to an increase in cost. Furthermore, the device of Patent Document 1 requires an end plate for preventing water from entering the joint and leakage of grease in the joint, which contributes to an increase in cost.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a low-cost wheel bearing device that is lightweight and compact.

  In order to achieve such an object, the present invention provides a wheel bearing device in which a hub wheel integrally having a wheel mounting flange on the outer periphery, a constant velocity universal joint, and a double row rolling bearing are unitized. One inner rolling surface of the rolling bearing is formed on the outer periphery of the hub wheel, and the other inner rolling surface is formed on the outer periphery of the outer joint member of the constant velocity universal joint, and the cylinder extends in the axial direction of the outer joint member. A serration is formed on the inner periphery of the small-diameter step portion having a shape, a serration is formed on the outer periphery of the shaft portion extending in the axial direction of the hub wheel, and a screw portion is provided at the tip of the shaft portion of the hub wheel, The shaft portion of the hub wheel is fitted into the small diameter step portion of the outer joint member, the serration on the inner periphery of the small diameter step portion and the serration on the outer periphery of the shaft portion are engaged, and the hub wheel is connected to the outer joint. A configuration in which a nut is fastened to a member And use.

  Thereby, torque can be transmitted by serration, so that the small-diameter step portion and the shaft portion can be reduced in weight and size. Moreover, since it is not necessary to make the inner diameter part of an outer joint member into a hollow stem shape long in the axial direction, the cutting process can be shortened and a low-cost wheel bearing device can be provided. Furthermore, since there is no fear of the intrusion of muddy salt water into the joint and the leakage of grease in the joint, an end plate is not necessary and the cost can be reduced.

  In the present invention, the heat treatment hardened layer may be formed on the serration by quenching and tempering by high frequency heating. Thereby, the strength of serration can be improved and a long-life wheel bearing device can be provided.

  In the present invention, the hub ring and the outer joint member can be fixed by fastening the nut, and a preload can be applied to the double row rolling bearing. Thereby, high bearing performance can be maintained and a long-life wheel bearing device can be provided.

  Further, in the present invention, the nut can be integrally fixed to the male screw portion by crimping or welding the end face of the nut. Thereby, the nut can be prevented from being loosened, and a long-life wheel bearing device can be provided.

  Further, according to the present invention, the inner diameter portion of the hub wheel can be thinned. Thereby, the weight of a bearing apparatus can be reduced.

  A wheel bearing device according to the present invention is a wheel bearing device in which a hub wheel, a constant velocity universal joint, and a double row rolling bearing integrally having a wheel mounting flange on an outer periphery thereof are unitized, and the double row rolling device. One inner rolling surface of the bearing is formed on the outer periphery of the hub wheel, and the other inner rolling surface is formed on the outer periphery of the outer joint member of the constant velocity universal joint. The cylindrical shape extends in the axial direction of the outer joint member. Serrations are formed on the inner periphery of the small diameter stepped portion, serrations are formed on the outer periphery of the shaft portion extending in the axial direction of the hub wheel, and a screw portion is provided at the tip of the shaft portion of the hub wheel, The shaft portion of the hub wheel is fitted into the small diameter step portion of the outer joint member, the serration on the inner periphery of the small diameter step portion and the serration on the outer periphery of the shaft portion are engaged, and the hub wheel is connected to the outer joint member. The nut is fastened to the Torque can be transmitted through the motor, making the small-diameter stepped part and the shaft part lighter and more compact, and it is not necessary to cut the inner diameter part of the outer joint member into a hollow stem shape that is long in the axial direction by cutting. A bearing device can be provided.

  A wheel bearing device in which a hub wheel, a constant velocity universal joint, and a double-row rolling bearing integrated with a wheel mounting flange on the outer periphery are unitized, wherein one inner rolling surface of the double-row rolling bearing is On the outer periphery of the hub wheel, the other inner rolling surface is formed on the outer periphery of the outer joint member of the constant velocity universal joint, and the serration is formed on the inner periphery of the cylindrical small-diameter step portion extending in the axial direction of the outer joint member. And a serration is formed on the outer periphery of the shaft portion extending in the axial direction of the hub wheel, and a screw portion is provided at the tip of the shaft portion of the hub wheel, and the shaft portion of the hub wheel is the outer joint member. The inner ring serration of the small diameter step portion and the serration of the outer periphery of the shaft portion mesh with each other, and the hub wheel is fastened with a nut to the outer joint member.

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

  This wheel bearing device has a so-called fourth generation configuration in which the hub wheel 1, the double row rolling bearing 2 and the constant velocity universal joint 3 are detachably unitized. The double-row rolling bearing 2 includes an outer member 7, an inner member 8, and double-row rolling elements (balls) 9 and 9. In addition, although the structure which consists of a double row angular contact ball bearing which used the ball for the rolling element 9 here is illustrated, the double row tapered roller bearing which used the tapered roller for the rolling element 9 may be sufficient.

  The outer member 7 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and integrally has a vehicle body mounting flange 7b for mounting to the vehicle body (not shown) on the outer periphery. Are formed with double-row outer rolling surfaces 7a, 7a. The double row outer rolling surfaces 7a, 7a are subjected to a hardening process with a surface hardness of 58 to 64 HRC by induction hardening.

  On the other hand, the inner member 8 includes the hub wheel 1 and the outer joint member 14 of the constant velocity universal joint 3. The inner member 8 is formed with double-row inner rolling surfaces 1a and 14a facing the outer rolling surfaces 7a and 7a of the outer member 7 described above. Of these double-row inner rolling surfaces 1 a and 14 a, one (outer side) inner rolling surface 1 a is on the outer periphery of the hub wheel 1, and the other (inner side) inner rolling surface 14 a is the outer periphery of the outer joint member 14. Are integrally formed. And the double row rolling elements 9 and 9 are accommodated between these both rolling surfaces, respectively, and are hold | maintained by the holder | retainers 10 and 10 so that rolling is possible. The pitch circle diameter of the inner rolling element 9 is set larger than the pitch circle diameter of the outer rolling element 9.

  Seals 11 and 12 are attached to the opening of the annular space formed between the outer member 7 and the inner member 8, and leakage of lubricating grease sealed inside the bearing, rainwater and Prevents dust from entering.

  The hub wheel 1 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end portion on the outer side. A female screw 4a for fastening a wheel bolt (not shown) for fixing the wheel is formed in the circumferential direction of the wheel mounting flange 4 at equal intervals. A seal land portion 13 is formed on the outer periphery of the base portion of the wheel mounting flange 4 so that the seal lip of the seal 12 is in sliding contact therewith. An inner rolling surface 1 a is formed on the inner side of the seal land portion 13. A shaft portion 1b extending in the axial direction is formed on the inner side of the inner rolling surface 1a. Serrations (or splines) are formed on the outer periphery of the shaft portion 1b. A male screw portion 1c is formed on the inner side of the shaft portion 1b. Further, the inner diameter portion 1d of the hub wheel 1 is thinned so as not to affect the strength in order to reduce the material cost.

  The hub wheel 1 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and extends from the seal land portion 13 to which the outer seal 12 is in sliding contact to the serrations of the inner rolling surface 1a and the shaft portion 1b. The outer peripheral surface is hardened by induction hardening and tempering so that the surface hardness is in the range of 58 to 64 HRC. As a result, not only the wear resistance of the seal land 13 is improved, but also the mechanical strength against the rotational bending load applied to the wheel mounting flange 4 is sufficient, and the durability of the hub wheel 1 is further improved. To do.

  The constant velocity universal joint 3 includes an outer joint member 14, a joint inner ring 15, a cage 16 and a torque transmission ball 17. The outer joint member 14 includes a cup-shaped mouth portion 18, a cylindrical portion 19 that extends from the mouth portion 18 toward the outer side in the axial direction, an inner rolling surface 14 a provided on the outer periphery of the outer side of the cylindrical portion 19, and an inner side A small-diameter step portion 20 having a cylindrical shape extending on the outer side in the axial direction of the rolling surface 14a is formed. Curved track grooves 18a and 15a extending in the axial direction are formed on the inner periphery of the mouse portion 18 and the outer periphery of the joint inner ring 15, respectively. Serrations (or splines) are formed on the inner periphery of the small diameter step portion 20.

  The outer joint member 14 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon, such as S53C, and extends from the inner raceway surface 14a to the inner periphery of the small-diameter step portion 20 including the track grooves 18a and 15a. The surface is hardened in the range of 58 to 64 HRC by induction hardening and tempering.

  In the present embodiment, the shaft portion 1 b of the hub wheel 1 is fitted to the small diameter step portion 20 of the outer joint member 14. Torque can be transmitted by the engagement of the serration on the inner periphery of the small diameter step portion 20 with the serration on the outer periphery of the shaft portion 1b. After fitting the hub wheel 1 to the outer joint member 14, the outer joint member 14 and the hub wheel 1 are fixed by fastening a nut 21 to the male thread 1 c of the hub wheel 1. Here, the fixing portion 22 is formed by caulking or welding the screw fastening portion of the end surface of the nut 21. By this fixing portion 22, the nut 21 is integrally fixed to the male screw portion 1c, and the nut 21 is prevented from loosening. At this time, preload can be applied to the double row rolling bearing 2 by tightening both members with nuts. In addition, the serration formed in this small diameter step part 20 and the axial part 1b calculates | requires the relationship between a diameter and length from required transmission torque, and sets the serration fitting length as short as possible. Thereby, the inner and outer diameter cutting range of the outer joint member 14 can be shortened as much as possible, and the number of cutting processes and the material cost can be reduced.

  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 fourth-generation wheel bearing device for driving wheels.

It is a longitudinal section showing an embodiment of a wheel bearing device concerning the present invention.

Explanation of symbols

1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub wheel 1a, 14a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Inner rolling surface 1b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... Shaft 1c ... Male thread 1d ... Inner diameter 2 ... ················ Double row rolling bearing 3 · · Wheel mounting flange 4a · · · · · · bolt fastening female screw 7 · · · · · · Outer member 7a ... Outer rolling surface 7b ... Body mounting flange 8 ... Inner member 9 ... rolling element 10 ... cage 11, 1 ············································································· Outer joint Member 15 ... Joint inner ring 15a, 18a ... Track groove 16 ... Cage 17 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Torque transmission ball 18 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Mouse part 19 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ Cylinder part 20 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Small diameter step part 21 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Nut 22 ········Fixed part

Claims (5)

A wheel bearing device in which a hub wheel, a constant velocity universal joint, and a double-row rolling bearing that integrally have a wheel mounting flange on the outer periphery are unitized,
One inner rolling surface of the double row rolling bearing is formed on the outer periphery of the hub wheel, and the other inner rolling surface is formed on the outer periphery of the outer joint member of the constant velocity universal joint,
Serrations are formed on the inner periphery of the cylindrical small-diameter step portion extending in the axial direction of the outer joint member, serrations are formed on the outer periphery of the shaft portion extending in the axial direction of the hub wheel, and the shaft portion of the hub wheel. A threaded portion is provided at the tip of the hub wheel, and the shaft portion of the hub wheel is fitted into the small diameter step portion of the outer joint member, and the serration on the inner periphery of the small diameter step portion meshes with the serration on the outer periphery of the shaft portion. And the hub wheel is nut-fastened to the outer joint member.   The wheel bearing device according to claim 1, wherein a heat treatment hardened layer is formed on the serration by quenching and tempering by induction heating.   The wheel bearing device according to claim 1 or 2, wherein the hub wheel and the outer joint member are fixed by the nut fastening, and a preload is applied to the double row rolling bearing.   The wheel bearing device according to any one of claims 1 to 3, wherein the nut is integrally fixed to the male screw portion by crimping or welding the end face of the nut. The wheel bearing device according to any one of claims 1 to 4, wherein an inner diameter portion of the hub wheel is thinned.

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