JP2007170608A - Bearing for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light weight and compact fourth-generation structure bearing for a wheel, which increases strength of a caulking part and secures durability over a long period of time. <P>SOLUTION: In the bearing having an outer joint member 14 fixed in an axial direction to a hub wheel 1 by the caulking part 21 formed by plastically deforming an end part of a shaft part 20 of the outer joint member 14 radial direction outward, an internal thread 22, and a tapered shape wedge surface 23 getting smaller diameter toward an inner side from the internal thread 22 are formed on an end part of the shaft part 20, balls 24 adopted as rolling elements for a rolling bearing are fitted on the wedge surface 23, and the balls 24 are press-fitted on the wedge surface 23 by threadedly engaging a screw plug 25 with the internal thread 22. Consequently, an end part of the shaft part 20 plastically deforms and diameter of the serration 20b is expanded with accompanying the plastic deformation, and an engagement part which was under a loose fit condition is changed to under a tight fit condition to increase strength of the caulking part 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel bearing device that rotatably supports a wheel of an automobile or the like, and more particularly to a wheel bearing device having a fourth generation structure that is lightweight and compact and improves the durability of a coupling portion. .

  Conventionally, a wheel bearing device for supporting a wheel of an automobile or the like is such that a hub wheel for mounting a wheel is rotatably supported via a rolling bearing, and has a desired bearing rigidity, and also against misalignment. Double row angular contact ball bearings exhibiting durability and low rotational torque are frequently used from the viewpoint of improving fuel efficiency.

  Further, the wheel bearing device has a structure called a first generation in which a wheel bearing composed of a double row angular ball bearing or the like is fitted between a knuckle and a hub wheel constituting a suspension device. The second generation structure in which the body mounting flange or the wheel mounting flange is directly formed on the outer periphery of the member, and the third generation structure in which one inner rolling surface is directly formed on the outer periphery of the hub wheel are mass-produced. Furthermore, a fourth generation structure has been developed that is lighter and more compact by directly forming inner rolling surfaces on the outer periphery of the outer joint member of the hub wheel and the constant velocity universal joint, and is about to be introduced into the market.

  As this fourth-generation wheel bearing device, one shown in FIG. 3 is known. In this wheel bearing device, a hub wheel 50, a double row rolling bearing 51, and a constant velocity universal joint 52 are unitized. The double-row rolling bearing 51 has a vehicle body mounting flange 53b integrally attached to a knuckle (not shown) on the outer periphery, and an outer side in which double-row outer rolling surfaces 53a and 53a are formed on the inner periphery. A member 53 and a wheel mounting flange 54 for mounting a wheel (not shown) at one end are integrally provided, and one inner rolling surface 50a facing the double row outer rolling surfaces 53a and 53a on the outer periphery. The hub wheel 50 in which a small-diameter step portion 50b extending in the axial direction from the inner rolling surface 50a is formed, and the small-diameter step portion 50b of the hub wheel 50 are fitted into the double-row outer rolling surfaces 53a and 53a. An inner member 56 composed of an outer joint member 55 formed with the other inner rolling surface 55a facing each other, double rows of balls 57, 57 accommodated between both rolling surfaces, and these double rows of balls 57 , 57 to hold the roller freely Is composed of a double row angular contact ball bearing having an 8 and 58. On the outer periphery of the hub wheel 50, a predetermined hardened layer is formed by induction hardening over the end face of the inner rolling surface 50a and the small-diameter stepped portion 50b from the seal land portion where the outer seal 65 is in sliding contact.

  The constant velocity universal joint 52 includes an outer joint member 55, a joint inner ring 59, a cage 60, and a torque transmission ball 61. The outer joint member 55 includes a cup-shaped mouth portion 62 and a shoulder that forms the bottom portion of the mouth portion 62. A portion 63 and a shaft portion 64 extending in the axial direction from the shoulder portion 63 are integrally provided. A serration 64a is formed on the outer periphery of the shaft portion 64, and engages with a serration 50c formed on the inner periphery of the hub wheel 50 so that torque can be transmitted. Further, a predetermined hardened layer is formed on the outer periphery of the outer joint member 55 by induction quenching from the seal land portion in which the inner seal 65 is in sliding contact to the inner rolling surface 55a and the shaft portion 64.

  Seals 65, 65 are attached to the opening portion of the annular space formed between the outer member 53 and the inner member 56, and leakage of lubricating grease sealed inside the bearing and rainwater or the like inside the bearing from the outside. Prevents dust from entering.

  Further, the end portion of the shaft portion 64 of the outer joint member 55 is plastically deformed radially outward and is caulked (oscillating caulking) to the end surface 67 located in the pilot portion 66 of the hub wheel 50, and this caulking portion. The outer joint member 55 is fixed to the hub wheel 50 in the axial direction by 68, and the end face of the small diameter step portion 50b of the hub wheel 50 and the shoulder 63 of the outer joint member 55 are abutted to manage the bearing preload amount. .

Here, by forming at least a portion of the end surface 67 of the hub wheel 50 in contact with the caulking portion 68 to be radially outwardly inclined toward the outer side, the contact area of the caulking portion 68 is increased, The strength of the fastening portion 68 is improved.
JP 2002-356101 A

  In such a conventional wheel bearing device, in order to increase the strength of the caulking portion 68, at least a portion of the end surface 67 of the hub wheel 50 that contacts the caulking portion 68 is inclined outwardly in the radial direction. Forming and increasing the contact area of the crimping portion 68 is an effective means. However, if the engaging portions of the serrations 50c and 64a that transmit torque have a backlash in the rotational direction, not only will the vehicle run stability and feeling be adversely affected, but also fretting will proceed to the engaging portions. When a moment load or the like is applied, this backlash is amplified and the strength of the caulking portion 68 may be reduced.

  The present invention has been made in view of such circumstances, and is a fourth-generation wheel bearing device having a lightweight and compact structure, with a loosely joined portion, and ensuring durability over a long period of time. It is intended to provide.

  In order to achieve such an object, the invention according to claim 1 of the present invention is a wheel bearing device in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized. The rolling bearing has an outer member in which a double row outer rolling surface is formed on the inner periphery, and a wheel mounting flange integrally formed at one end, and one end facing the outer rolling surface of the double row on the outer periphery. An inner rolling surface, a hub wheel formed with a cylindrical small-diameter stepped portion extending in the axial direction from the inner rolling surface, and the other inner rolling surface facing the double-row outer rolling surface on the outer periphery; An inner member made of an outer joint member of the constant velocity universal joint integrally formed with a shaft portion extending in the axial direction from the inner rolling surface, and between both rolling surfaces of the inner member and the outer member A plurality of rolling elements housed in a freely rotatable manner, and the shaft portion is fitted into the hub wheel via a serration. In addition, in the wheel bearing device in which the outer joint member is fixed in the axial direction with respect to the hub wheel by a caulking portion formed by plastically deforming the end portion radially outward, the end portion of the shaft portion A female screw and an inner peripheral surface extending in the axial direction from the female screw and set to a predetermined inner diameter, and a diameter-expanding member is fitted into the inner peripheral surface, and a screw plug is screwed into the female screw. Thereby, the said diameter-expansion member is hold | maintained in the state press-fitted in the said internal peripheral surface.

  Thus, in the wheel bearing device of the fourth generation structure in which the hub wheel and the outer joint member are plastically coupled by the caulking portion formed by swing caulking, a female screw is provided at the end of the shaft portion, and the female screw. An inner peripheral surface extending in the axial direction and set to a predetermined inner diameter is formed, and a diameter-expanding member is fitted into the inner peripheral surface. Since it is held in a state where it is press-fitted into the inner peripheral surface, the end portion of the shaft portion is elastically deformed, and the serration is expanded in accordance with this elastic deformation, and the serration engaging portion that has been loosely fitted Can be provided in a tight fitting state, the strength of the caulking portion can be increased, and a fourth-generation wheel bearing device having a long-term durability can be provided.

  According to a second aspect of the present invention, the inner peripheral surface of the shaft portion is formed as a tapered wedge surface having a small diameter toward the inner side, and the diameter-expanding member is formed of a ball. In addition, as in the invention described in claim 3, the inner peripheral surface of the shaft portion is formed in a cylindrical surface, and the diameter-expanding member is larger than the inner diameter of the cylindrical surface by a predetermined dimension. You may be comprised with the cylindrical roller formed in the diameter.

  Further, as in the invention described in claim 4, if the diameter-expanding member is composed of a rolling element applied to a rolling bearing, not only a characteristic of high hardness but also a stable dimension and high accuracy in a wide range are secured. And a desired amount of diameter expansion can be obtained.

  Further, as in the invention described in claim 5, if the shaft portion is formed in a hollow shape, it is possible to reduce the weight while securing the rigidity of the device, and to enhance the heat dissipation effect of the bearing portion. In addition, durability can be improved by suppressing temperature rise during operation.

  A wheel bearing device according to the present invention is a wheel bearing device in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized, and the double row rolling bearing has a double row on an inner periphery. An outer rolling surface formed with the outer rolling surface, a wheel mounting flange at one end, and an inner rolling surface facing the double row outer rolling surface on the outer periphery, and the inner rolling surface. A hub wheel formed with a cylindrical small-diameter stepped portion extending in the axial direction from the running surface, the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and the axial direction from the inner rolling surface An inner member composed of an outer joint member of the constant velocity universal joint integrally formed with a shaft portion extending in the direction of the shaft, and a plurality of rolls accommodated between both rolling surfaces of the inner member and the outer member. And the shaft portion is fitted into the hub wheel via serrations, and the end portion is radially outward In the wheel bearing device in which the outer joint member is fixed to the hub wheel in the axial direction by a caulking portion formed by plastic deformation to a female screw, an internal thread is provided at the end of the shaft portion, and the axial direction from the female screw is determined in the axial direction. An inner peripheral surface extending to a predetermined inner diameter is formed, and a diameter-expanding member is inserted into the inner peripheral surface, and a screw plug is screwed onto the female screw, whereby the diameter-expanding member is Since it is held in a state where it is press-fitted into the surface, the end portion of the shaft portion is elastically deformed, and the serration is expanded with this elastic deformation, and the engagement portion of the serration that has been loosely fitted is tight. Thus, it is possible to provide a wheel bearing device having a fourth generation structure in which the fitting state is maintained, the strength of the caulking portion is increased, and durability is ensured over a long period of time.

  A wheel bearing device in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized, wherein the double row rolling bearing has an outer periphery formed with a double row outer rolling surface. And a cylindrical member extending in the axial direction from the inner rolling surface, and one inner rolling surface facing the outer rolling surface of the double row on the outer periphery. A hub wheel formed with a small diameter step portion, the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a shaft portion extending in the axial direction from the inner rolling surface are integrally formed. An inner member composed of an outer joint member of the constant velocity universal joint, and a double row rolling element that is accommodated so as to roll freely between both rolling surfaces of the inner member and the outer member. Clamping formed by fitting the end part into the hub wheel via serrations and plastically deforming the end part radially outward In the wheel bearing device in which the outer joint member is fixed in the axial direction with respect to the hub wheel, a female screw is provided at an end of the shaft portion, and a tapered wedge surface having a small diameter from the female screw toward the inner side. A ball applied as a rolling element of a rolling bearing is inserted into the wedge surface, and a screw plug is screwed into the female screw to hold the ball in a state of being press-fitted into the wedge surface. ing.

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. 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 is referred to as a fourth generation, and includes a hub wheel 1, a double row rolling bearing 2 and a constant velocity universal joint 3 as a unit. The double-row rolling bearing 2 includes an outer member 4, an inner member 5, and double-row rolling elements (balls) 6 and 6. The inner member 5 includes a hub wheel 1 and an outer joint member 14 (described later) fitted in the hub wheel 1 so as to be able to transmit torque.

  The outer member 4 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 4b for mounting to a vehicle body (not shown) on the outer periphery. Arc-shaped double-row outer rolling surfaces 4a and 4a are formed. The double-row outer raceway surfaces 4a and 4a are formed with a predetermined hardened layer having a surface hardness of 58 to 64 HRC by induction hardening.

  On the other hand, the hub wheel 1 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has a wheel mounting flange 7 for mounting a wheel to an end portion on the outer side. A plurality of hub bolts 8 are planted at equal intervals in the circumferential direction. Also, on the outer periphery of the hub wheel 1, one (outer side) arcuate inner rolling surface 1a facing the double row outer rolling surfaces 4a, 4a, and an axial direction from the inner rolling surface 1a. An extending cylindrical small-diameter step portion 1b is formed, and a serration (or spline) 1c for torque transmission is formed on the inner periphery. Then, the surface hardness is set to 58 to 64 HRC by induction hardening from the seal land portion 7a in which the outer peripheral seal 10 is in sliding contact with the inner peripheral serration 1c portion to the inner rolling surface 1a and the end surface of the small diameter step portion 1b. Predetermined hardened layers 11 and 12 are formed in the range. As a result, not only the wear resistance of the seal land 7a which is the base of the serration 1c and the wheel mounting flange 7 is improved, but also sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange 7 is obtained. In addition, the durability of the hub wheel 1 is improved.

  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 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has a cup-shaped mouth portion 18, a shoulder portion 19 that forms the bottom portion of the mouth portion 18, and the shoulder portion 19. A shaft portion 20 extending in the axial direction from is integrally formed. The shaft portion 20 has an inrow portion 20a that is cylindrically fitted to the small-diameter step portion 1b of the hub wheel 1 through a predetermined radial clearance, and a serration (or spline) that engages the serration 1c of the hub wheel 1 on the outer periphery of the end portion. ) 20b is formed. As described above, since the small diameter step portion 1b of the hub wheel 1 can be supported by the cylindrical surface of the in-row portion 20a, the rigidity of the device is increased and sufficient rigidity can be secured even when a large moment load is applied. , Durability can be improved.

  Further, the shaft portion 20 protruding from the shoulder portion 19 is formed in a hollow shape. Thereby, while ensuring the rigidity of an apparatus, weight reduction can be achieved, the heat dissipation effect of a bearing part can be improved, the temperature rise during operation can be suppressed, and the durability can be improved. Further, a curved track groove 18a extending in the axial direction is formed on the inner periphery of the mouth portion 18, and a track groove 15a corresponding to the track groove 18a is formed on the outer periphery of the joint inner ring 15, and both the track grooves are formed. A torque transmission ball 17 is accommodated via a cage 16 between 18a and 15a.

  On the outer periphery of the shoulder portion 19 of the outer joint member 14, the other (inner side) arcuate inner rolling surface 14 a facing the double row outer rolling surfaces 4 a, 4 a is formed. And the double row rolling elements 6, 6 between the double row outer rolling surfaces 4a, 4a of the outer member 4 described above and the double row inner rolling surfaces 1a, 14a of the inner member 5 opposed thereto. Is held by the cages 9 and 9 so as to be freely rollable. Further, seals 10 and 10 are attached to the end portion of the outer member 4 to prevent leakage of the lubricating grease sealed inside the bearing and intrusion of rainwater, dust and the like into the bearing from the outside. Here, a predetermined hardened layer having a surface hardness in the range of 58 to 64 HRC by induction quenching from the seal land portion 14b slidably in contact with the inner seal 10 to the inner rolling surface 14a and the inrow portion 20a of the shaft portion 20. 13 is formed. Thereby, not only the wear resistance of the seal land portion 14b and the in-row portion 20a is improved, but also the mechanical strength is sufficient with respect to the applied rotational bending load, and the durability of the outer joint member 14 is improved. . Here, a double-row angular contact ball bearing using balls as the rolling elements 6 is illustrated, but the wheel bearing device according to the present invention is not limited to this, and a double-row conical roller using tapered rollers as the rolling elements 6. It may be a roller bearing.

  Here, in the present embodiment, the end portion of the shaft portion 20 is plastically deformed radially outward to be swung and caulked to form a caulking portion 21. The end face of the small-diameter stepped portion 1b is abutted against the shoulder portion 19 and a predetermined preload is applied to the double-row rolling bearing 2 by the caulking portion 21, thereby the hub wheel 1 and the outer joint member. 14 are integrally plastically coupled. Further, a female screw 22 and a tapered wedge surface 23 having a small diameter from the female screw 22 toward the inner side are formed on the inner periphery of the end portion of the shaft portion 20. Then, a ball (expansion member) 24 applied as a rolling element of a rolling bearing is inserted into the wedge surface 23, and the ball 24 is pressed to the inner side by screwing the screw plug 25 to the female screw 22, thereby 24 is held in a state of being press-fitted into the wedge surface 23. By pushing the ball 24, the end of the shaft portion 20 is elastically deformed, and the serration 20b is enlarged in accordance with the elastic deformation, and the engagement portions of the serrations 1c and 20b that are loosely fitted are tight. It is possible to provide a wheel bearing device having a fourth generation structure that is in a fitted state, increases the strength of the caulking portion 21, and ensures durability over a long period of time. In this embodiment, since the balls 24 used as rolling elements for bearings are used, not only the characteristics of high hardness but also a wide range of stable dimensions and high precision balls 24 can be obtained, and a desired diameter expansion amount can be obtained. Can be set.

  FIG. 2 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. In this embodiment, only the configuration of the shaft portion of the above-described embodiment is different, and other parts having the same parts or the same functions are denoted by the same reference numerals and detailed description thereof is omitted.

  The shaft portion 20 ′ projecting from the shoulder portion 19 of the outer joint member 14 has an inrow portion 20 a and a serration 20 b formed on the outer periphery of the end portion of the inrow portion. Further, a female screw 22 and a cylindrical surface 26 extending in the axial direction from the female screw 22 are formed on the inner periphery of the end of the shaft portion 20 ′. A cylindrical roller (expansion member) 27 applied as a rolling element of a rolling bearing is fitted into the cylindrical surface 26, and the cylindrical roller 27 is pressed to the inner side by screwing the screw plug 25 to the female screw 22. A cylindrical roller 27 is press-fitted into the cylindrical surface 26. Since the outer diameter of the cylindrical roller 27 is set to a predetermined size larger than the inner diameter of the cylindrical surface 26, the end of the shaft portion 20 ′ is elastically deformed by the press-fitting of the cylindrical roller 27 as in the above-described embodiment. And the serration 20b is expanded in diameter with this elastic deformation, and the radial play of the engaging part of the serrations 1c and 20b can be suppressed.

  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 wheel bearing device having a fourth generation structure in which a hub wheel, a double row rolling bearing, and a constant velocity universal joint are unitized.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. 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.

Explanation of symbols

1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub wheel 1a, 14a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Inner rolling surface 1b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... Small diameter step 1c, 20b ... Serration 2 ... Double row rolling bearing 3 ...・ ・ ・ ・ ・ ・ ・ ・ Constant velocity universal joint 4 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer member 4a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Outer rolling surface 4b ... Body mounting flange 5 ... Inner member 6 ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Rolling element 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wheel mounting flange 7a, 14b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Seal land 8・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub bolt 9 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hold 10 ··············· Seal 11, 12, 13 ··························· Fitting member 15 ... Fitting inner ring 15a, 18a ... Track groove 16 ...・ Cage 17 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Torque transmission ball 18 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Mouse 19・ ・ ・ ・ ・ Shoulder 20, 20 ′ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shaft 20a ・ ・ ・ ・ ・ ・ ・ ・ In-row 21 ・ ・ ・ ・ ・ ・ ・ ・··························································································· Wedge surface 24・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Ball 25 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Screw plug 6 ... Cylindrical surface 27 ... Cylindrical roller 50 ... ..Hub wheels 50a, 55a ... inner rolling surface 51 ... double row rolling bearing 52 ... ... Constant velocity universal joint 53 ... Outer member 53a ... Outer rolling surface 54 ... Wheel mounting flange 55 ... Outer joint member 56 ...・ ・ ・ ・ Inner member 57 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Ball 58 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Retainer 59 ・ ・ ・ ・ ・ ・... Joint inner ring 60 ... Cage 61 ... .... Torque transmission ball 62 ... Mouse part 63 ... Shoulder part 64 ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shaft 65 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Seal 66 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Pilot 67・ ・ ・ ・ ・ ・ ・ ・ ・ ・ End face 68 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Clamping part

Claims (5)

A wheel bearing device in which a hub wheel, a double row rolling bearing and a constant velocity universal joint are unitized,
The double row rolling bearing is an outer member in which a double row outer rolling surface is formed on the inner periphery,
One end has a wheel mounting flange integrally, and on the outer periphery is one inner rolling surface facing the double row outer rolling surface, and a cylindrical small-diameter step portion extending in the axial direction from the inner rolling surface. The above-described constant velocity freely in which the formed hub wheel, the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and the shaft portion extending in the axial direction from the inner rolling surface are integrally formed. An inner member made of an outer joint member of the joint;
A double row rolling element housed in a freely rolling manner between the rolling surfaces of the inner member and the outer member;
The outer joint member is axially fitted to the hub wheel by a crimping portion formed by the shaft portion being fitted into the hub wheel via serrations and plastically deforming the end portion radially outward. In a fixed wheel bearing device,
A female screw and an inner peripheral surface extending in the axial direction from the female screw and set to a predetermined inner diameter are formed at the end of the shaft portion, and a diameter-expanding member is fitted and inserted into the inner peripheral surface. The wheel bearing device according to claim 1, wherein the diameter-expanding member is held in a state of being press-fitted into the inner peripheral surface by being screwed into the female screw.   2. The wheel bearing device according to claim 1, wherein an inner peripheral surface of the shaft portion is formed as a tapered wedge surface having a small diameter toward the inner side, and the diameter increasing member is formed of a ball.   2. The wheel according to claim 1, wherein an inner peripheral surface of the shaft portion is formed in a cylindrical surface, and the diameter-expanding member is configured by a cylindrical roller having a predetermined diameter larger than an inner diameter of the cylindrical surface. Bearing device.   The wheel bearing device according to any one of claims 1 to 3, wherein the diameter-expanding member is configured by a rolling element applied to a rolling bearing.   The wheel bearing device according to any one of claims 1 to 4, wherein the shaft portion is formed in a hollow shape.

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