JP2022129698A - Wheel bearing device and power transmission structure - Google Patents

Abstract

To provide a wheel bearing device and a power transmission structure that prevents the generation of stick slip sound for a long time, even by the strong torque of an EV motor.SOLUTION: A stem portion 62 is projected out from a bottom portion 61a of a mouth portion 61 of an outside joint member of a constant velocity universal joint. The stem portion is made to be a male spline shaft 65 fitted with a female spline hole of a hub ring. An outer diameter of a mouth side root portion of the male spline shaft is made to be larger than the minimum diameter satisfying torque transmission capacity, and the other part of the male spline shaft is made to be smaller than the outer diameter of the mouth side root portion and satisfy the torque transmission capacity.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wheel bearing device for supporting a wheel of a vehicle such as an automobile. The present invention relates to a wheel bearing device that rotatably supports a rear wheel of a car or an RR car and all wheels of a 4WD car with respect to a suspension system.

A power transmission device that transmits the engine power of a vehicle such as an automobile to the wheels transmits the power from the engine to the wheels, and also the radial and axial displacement from the wheels that occurs when the vehicle bounces when running on rough roads or when the vehicle turns. , and moment displacement must be allowed. For this reason, for example, one end of a drive shaft interposed between the engine side and the drive wheel side is connected to a differential through a sliding constant velocity universal joint, and the other end is a fixed constant velocity universal joint. is connected to the driving wheels via a wheel bearing device including a

Various structures have been proposed for this wheel bearing device, and for example, a structure shown in FIG. 6 is known. This wheel bearing device includes an outer member 1 integrally having a vehicle body mounting flange 1b for mounting to a vehicle body on the outer periphery thereof, and having double rows of outer raceway surfaces 1a, 1a integrally formed on the inner periphery thereof; A wheel mounting flange 4 for mounting a wheel (not shown) is integrally provided at one end, and an inner raceway surface 2a facing one of the double-row outer raceway surfaces 1a, 1a on the outer periphery, and the inner raceway surface 2a. A hub wheel 2 formed with a cylindrical small diameter stepped portion 2b extending axially from a raceway surface 2a, and a double row outer raceway surface 1a, 1a which is press-fitted into the small diameter stepped portion 2b of the hub wheel 2 and formed on the outer periphery. An inner member 5 composed of an inner ring 3 having an inner raceway surface 2a facing the other, and rolling between the raceway surfaces of the inner member 5 and the outer member 1 via cages 6, 6. It has double rows of balls 7, 7 which are freely accommodated, and seals 8, 9 which are mounted in openings of an annular space formed between the outer member 1 and the inner member 5. As shown in FIG.

The inner ring 3 is axially fixed to the hub wheel 2 by a caulking portion 10 formed by radially outwardly plastically deforming the end of the small-diameter stepped portion 2b of the hub wheel 2. A constant velocity universal joint 11 is connected. The outer joint member 12 of the constant velocity universal joint 11 includes a shoulder portion 13 forming the bottom of the cup-shaped mouth portion, and extending axially from the shoulder portion 13 to apply torque to the hub wheel 2 via serrations (splines) 14a. The hub wheel 2 and the outer joint member 12 are axially detachable via a fixing nut 15 with the shoulder portion 13 abutting against the caulking portion 10. is coupled to

It is known that torque is applied to the wheels of such a vehicle from the engine through the sliding constant velocity universal joint 11, and the drive shaft is twisted. As a result, a relative difference due to torsion occurs between the caulked portion 10 of the hub wheel 2 and the shoulder portion 13 of the outer joint member 12 . Due to the axial force due to the tightening of the nut 15, the contact surfaces of the caulked portion 10 and the shoulder portion 13 try to move together due to frictional resistance, but when the engine rotates at a low speed, for example, when the vehicle starts, a larger torque is applied. When the drive shaft is greatly twisted, the contact surface between the outer joint member 12 and the inner member 5 cannot withstand the frictional resistance, causing sudden slip and stick-slip noise.

Conventional methods for preventing such stick-slip noise include adjusting the friction coefficient of the contact surface between the inner member and the shoulder portion of the outer joint member (Patent Document 1), low-friction resin coating layer There have been proposals in which a plate formed with a is interposed (sandwiched) between the inner member and the shoulder portion of the outer joint member.

JP 2009-149183 A JP 2013-082351 A

In Patent Literatures 1 and 2, stick-slip of the contact surface due to torque transmission is suppressed, but the effect of the contact surface may deteriorate over time due to use of the vehicle, that is, wear of the contact surface, peeling of the coating film, etc. It was difficult to exert the function (function to suppress stick-slip) for a long period of time.

Also, in recent years, due to improvements in motors and batteries, electric vehicles that do not have an engine (hereinafter simply referred to as EV) are gaining prominence in the automobile market. The feature of EV is that it is a quiet car from zero start (running from a stopped state) to high speed range.

For this reason, compared to conventional automobiles with internal combustion engines, even the slightest noise is noticeable. Furthermore, the characteristic of the EV motor is that it generates a maximum torque immediately after starting and is used as a regenerative brake when decelerating the vehicle, so a load greater than that of an engine vehicle is applied to the contact surface. For this reason, an axle module (power transmission structure) that can effectively prevent stick-slip noise has been required for EVs.

In addition, the stick-slip sound on the contact surface is a high-frequency sound, a so-called metallic sound, that can be heard as it propagates through the vehicle body. It is necessary to take countermeasures against the source.

Therefore, in the present application, attention is paid to the occurrence and increase of backlash at the spline fitting portion of the wheel bearing device and the constant velocity universal joint, which is the source of stick-slip, and the fitting method (diameter size, male spline By improving the torsion angle of the spline) and strength (heat treatment of the female spline), it is possible to prevent stick-slip noise from occurring on the contact surface.
Wheel bearing device and power transmission structure that do not generate stick-slip noise (Askul module: a pair of constant velocity universal joints, an intermediate shaft connecting them, and a wheel bearing device connected to the constant velocity universal joint provided).

A wheel bearing device of the present invention comprises an outer member having a double-row outer raceway surface formed on its inner periphery and an inner member having a double-row raceway surface opposed to the outer raceway surface formed on its outer periphery. and double-row rolling elements interposed between the raceway surfaces of the outer member and the inner member, the inner member having a hub ring, and a constant velocity universal joint being spline-connected to the hub ring. A wheel bearing device to which the stem portion of is integrally connected,
The stem portion protrudes from the bottom portion of the mouth portion of the outer joint member of the constant velocity universal joint. The outer diameter of the side base is larger than the minimum diameter that satisfies the torque transmission capacity, and the other part of the male spline shaft is made smaller than the outer diameter of the mouth side base to satisfy the torque transmission capacity. This is what I did.

According to the wheel bearing device of the present invention, the spline fitting between the stem portion of the constant velocity universal joint and the hub wheel can be increased in diameter on the root side. As a result, deformation and wear on the root side can be prevented.

It is preferable to impart a twist angle to the spline convex teeth of the mouth-side root portion of the male spline shaft. Assuming that the torsion angle of the convex spline teeth of the male spline shaft of the constant velocity universal joint is the forward rotation of the male spline shaft when the vehicle moves forward, the contact of the convex spline teeth affects the torque transmission when the vehicle starts moving. By imparting a twist angle to the spline convex teeth of the male spline shaft in the direction in which the male spline shaft is released from the accompanying torsion, contact pressure can be alleviated, and deformation and wear of the female spline of the hub wheel can be suppressed. .

The generatrix shape of the spline convex tooth at the root portion on the mouth side of the male spline shaft may be arcuate. In this way, even with the arc shape, when the vehicle starts moving, the contact of the spline convex teeth can be set so as to be released from the torsion of the male spline shaft due to torque transmission, and the contact pressure can be reduced. Deformation and wear can be suppressed.

The generatrix shape of the spline convex teeth at the root portion on the mouth side of the male spline shaft may be wave-shaped. Such a corrugated shape increases the number of contact portions between the convex spline teeth of the male spline shaft and the concave spline teeth of the female spline hole, thereby dispersing the load. Therefore, when the vehicle starts moving, the contact of the spline convex teeth can be set so as to be released from the torsion of the male spline shaft due to torque transmission, the contact pressure can be reduced, and the deformation and wear of the female spline of the hub wheel can be suppressed. be able to.

It is preferable that the inner peripheral portion of the inboard side opening of the female spline hole of the hub wheel is heat-cured. The opening of the female spline hole on the inboard side is prone to deformation and wear when a torque load is applied. can be effectively prevented.

A first power transmission structure of the present invention is a power transmission structure comprising a pair of left and right drive shafts, each drive shaft comprising a pair of constant velocity universal joints and an intermediate shaft connecting the constant velocity universal joints. wherein the axial length of the intermediate shaft of the left and right drive shafts is different, the constant velocity universal joint disposed on the wheel side is connected to the wheel bearing device, and the mouth side base of the left and right constant velocity universal joints The torsion direction of the spline convex teeth of the part is made different.

A second power transmission structure of the present invention is a power transmission structure comprising a pair of left and right drive shafts, each drive shaft comprising a pair of constant velocity universal joints and an intermediate shaft connecting the constant velocity universal joints. wherein the axial length of the intermediate shaft of the left and right drive shafts is different, the constant velocity universal joint disposed on the wheel side is connected to the wheel bearing device, and the mouth side base of the left and right constant velocity universal joints The arc shape of the spline convex teeth of the part is symmetrical.

A third power transmission structure of the present invention is a power transmission structure comprising a pair of left and right drive shafts, each drive shaft comprising a pair of constant velocity universal joints and an intermediate shaft connecting the constant velocity universal joints. , the axial length of the intermediate shaft of the left and right drive shafts is different, the constant velocity universal joint disposed on the wheel side is connected to the wheel bearing device, and at least the spline convex tooth is given a twist angle , making the generatrix shape of the spline convex teeth circular, or making the generatrix shape of the spline convex teeth wavy, and the mouth-side root portion of the left and right constant velocity universal joints It has a different spline convex tooth shape.

In the present invention, even when abrupt torque transmission occurs in the spline fitting between the hub wheel and the stem portion of the constant velocity universal joint (such as when an EV vehicle starts moving), the portion where the contact surface pressure increases can be strengthened. It is possible to suppress the occurrence of looseness in the fitting portion, and reduce the stick-slip noise generated between the inner member (hub wheel) and the outer joint member of the constant velocity universal joint over a long period of time.

FIG. 4 is a side view showing the stem portion of the outer joint member of the constant velocity universal joint that is connected to the hub wheel of the wheel bearing device according to the present invention; 1 is a cross-sectional view of a wheel bearing device according to the present invention; FIG. 1 is a simplified diagram of a power transmission structure (askle module) of the present invention; FIG. The male spline shaft and the female spline hole are shown, (a) is a cross-sectional view of the large diameter portion, and (b) is a cross-sectional view of the small diameter portion. The relationship between the spline convex teeth of the male spline shaft and the spline concave teeth of the female spline hole is shown, (a) is a simplified diagram when the twist angle is given to the spline convex teeth, and (b) is the generatrix of the spline convex teeth. It is a simplified diagram when the shape is an arc shape, and (c) is a simplified diagram when the generatrix shape of the spline convex tooth is a wavy shape. FIG. 2 is a cross-sectional view of a conventional wheel bearing device;

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. FIG. 3 shows a power transmission structure according to the present invention, which includes a pair of drive shafts 51A, 52B each connected to a pair of constant velocity universal joints 53A, 54A. , 53B, 54B, and intermediate shafts 55A, 55B connecting the pair of constant velocity universal joints 53A, 54A, 53B, 54B.

Fixed constant velocity universal joints are used for the constant velocity universal joints 53A and 53B, and sliding constant velocity universal joints are used for the constant velocity universal joints 54A and 54B. The fixed constant velocity universal joint includes an outer joint member 60, an inner joint member (not shown) disposed inside the outer joint member 60, and a torque interposed between the outer joint member 60 and the inner joint member. A plurality of torque transmission members (not shown) that transmit torque, and a cage (not shown) interposed between the outer joint member 60 and the inner joint member and holding balls as torque transmission members are configured as main members. be. The inner joint member is spline-fitted by press-fitting the end of the intermediate shaft into the inner diameter of the hole to be coupled to the shaft 55 (55A, 55B) so that torque can be transmitted.

The outer joint member 60 is composed of a mouth portion 61 and a shaft portion (also called a stem portion) 62. The mouth portion 61 is bowl-shaped with one end open and has a plurality of axially extending track grooves on its inner spherical surface. They are formed at equal intervals in the circumferential direction. The track groove extends to the open end of the mouth portion. The inner joint member has a plurality of axially extending track grooves formed at equal intervals in the circumferential direction on its outer spherical surface.

Also, the opening of the mouth portion 61 is closed with a boot 63 . The boot 63 includes a large diameter portion 63a, a small diameter portion 63b, and a bellows portion 63c connecting the large diameter portion 63a and the small diameter portion 63b. The large-diameter portion 63a is fitted over the opening of the mouth portion 61 and fastened with a boot band 64 in this state. Also, the small diameter portion 63b is fitted onto the boot mounting portion of the shaft 55, and is fastened with the boot band 64 in this state.

The sliding constant velocity universal joint includes an outer joint member 70, an inner joint member, a ball as a torque transmission member interposed between the outer joint member 70 and the inner joint member, and a pocket for holding the ball. and a cage having The outer joint member is spline-fitted by press-fitting the end of the intermediate shaft 55 (55A, 55B) into the inner diameter of the hole to be coupled to the shaft so that torque can be transmitted.

The outer joint member 70 is composed of a mouth portion 71 and a shaft portion (also called a stem portion) 72. A plurality of axially extending track grooves are formed on the inner diameter surface of the outer joint member 70 at regular intervals in the circumferential direction. , a plurality of axially extending track grooves are formed at equal intervals in the circumferential direction on the outer diameter surface thereof.

Also, the opening of the mouth portion 71 is closed with a boot 73 . The boot 73 includes a large diameter portion 73a, a small diameter portion 73b, and a bellows portion 73c connecting the large diameter portion 73a and the small diameter portion 73b. The large-diameter portion is fitted over the opening of the mouth portion and fastened with a boot band 74 in this state. Also, the small diameter portion 73b is fitted onto the boot mounting portion of the shaft 55, and is fastened with a boot band 74 in this state.

By the way, a fixed constant velocity universal joint allows only angular displacement, and a sliding constant velocity universal joint allows not only angular displacement but also axial displacement (plunging). Joints include a Barfield type constant velocity universal joint (BJ) in which the groove bottom of the track groove consists only of an arc part, and an undercut-free type constant velocity universal joint in which the groove bottom of the track groove consists of an arc part and a straight part ( UJ), etc. Further, sliding constant velocity universal joints include tripod constant velocity universal joints, double offset constant velocity universal joints, cross groove constant velocity universal joints, and the like. These various types of constant velocity universal joints can be used in the present invention.

A stem portion 72 of the outer joint member 70 of the sliding constant velocity universal joints 54A, 54B is connected to a power portion 75 including a motor, a speed reducer, and a differential. Then, the outer joint members 60, 60 of the fixed constant velocity universal joints 53A, 53B are connected to the wheel bearing device.

As shown in FIG. 2, the wheel bearing device is mainly composed of an outer member 22, a hub ring 23, an inner ring 24, balls 25 as rolling elements, and a retainer 26, and is called a so-called third generation. It has configuration. In the following description, the side that is closer to the outside of the vehicle when assembled to the vehicle is called the outer side (left side in FIG. 2), and the side that is closer to the center is called the inner side (right side in FIG. 2).

The inner member 21 is composed of a hub ring 23 and an inner ring 24 . The hub wheel 23 has an inner raceway surface 29 directly formed on its outer periphery that faces one (outer side) of the double-row outer raceway surfaces 27 of the outer member 22, and a wheel (not shown) at the end on the outer side. ) is integrally formed with a wheel mounting flange (not shown).

A cylindrical small-diameter stepped portion 30 extending axially toward the inner side from the inner raceway surface 29 is formed on the outer periphery of the hub wheel 23, and the inner ring 24 is press-fitted into the small-diameter stepped portion 30 with a predetermined interference. An inner raceway surface 29 is formed on the outer circumference of the inner ring 24 so as to face the other (inner side) of the double-row outer raceway surfaces 27 , 27 of the outer member 22 . A plurality of balls 25, 25 are incorporated between the outer raceway surfaces 27, 27 of the outer member 22 and the inner raceway surfaces 29, 29 of the inner member 21, and the balls 25 are accommodated in the retainer 26 at predetermined intervals in the circumferential direction. It is

A short cylindrical pilot 23a extending toward the outer side is provided on the outer end face of the hub wheel 23 . This pilot 23a guides the inner diameter surface (inner circumference) of the rotor of a disc brake (not shown). Also, the opening of the annular space formed between the outer member 22 and the inner member 21 is sealed by a pair of sealing devices 31 and 32 .

As shown in FIG. 1, the outer joint member 60 of the constant velocity universal joint 53 has a shoulder portion 61a forming the bottom of a cup-shaped mouth portion 61 and a stem portion 62 extending axially from the shoulder portion 61a. The stem portion 62 is formed with a male spline shaft 65 and a screw portion 66 (see FIG. 3) extending from the male spline shaft 65 .

As shown in FIG. 2, the hub wheel 23 is provided with a female spline hole 67, into which the male spline shaft 65 of the stem portion 62 of the outer joint member 60 is fitted (inserted). A nut member is screwed onto the threaded portion 66 of the stem portion 62 protruding from the spline hole 67 . As a result, the hub wheel 23 and the outer joint member of the constant velocity universal joint are integrated.

In this case, as shown in FIGS. 4(a) and 4(b), the male spline shaft 65 has spline convex teeth 68a and spline concave teeth 68b alternately formed along the circumferential direction on its outer diameter surface. The outer diameter of the base on the mouse side is made larger than the minimum diameter that satisfies the torque transmission capacity, and the other part of the male spline shaft 65 is made smaller than the outer diameter of the base on the mouse side. It has a diameter that satisfies the torque transmission capacity. That is, as shown in FIG. 1, the male spline shaft 65 has a large diameter portion 65a at the base on the mouth side and a small diameter portion 65b at the screw portion side of the large diameter portion 65a.

The outer diameter of the root portion on the mouse side, that is, the outer diameter of the large diameter portion 65a is the diameter of the circle drawn by the center of the tip surface of the tooth tip of the spline convex tooth 68a. It is the diameter of the circle drawn by the center of the tip surface of the tip of the convex tooth 68a. That is, when the outer diameter of the large-diameter portion 65a is D1 (see FIG. 4A) and the outer diameter of the small-diameter portion 65b is D2 (see FIG. 4B), D1>D2, and D1 is, for example, , 32.2 mm to 24.4 mm, D1-D2 is set to, for example, 1 mm to 2 mm.

Further, when the total length of the male spline shaft 65 is L, the length of the large diameter portion 65a is L1, and the length of the small diameter portion 65b is L2, then L=L1+L2 and L1:L2=1:2. do. The cross-sectional shape of the spline convex tooth 68a of the male spline shaft 65 is trapezoidal in the illustrated example, but may be a chevron shape with a convex rounded top.

As shown in FIGS. 4(a) and 4(b), the female spline hole 67 has spline convex teeth 69a and spline concave teeth 69b alternately arranged along the inner diameter surface of the axial hole of the hub wheel 23 along the circumferential direction. Corresponding to the male spline shaft 65, a large diameter portion 67a is formed on the inboard side, and a small diameter portion 67b is formed on the outboard side from the large diameter portion 67a. When the outer diameter of the large-diameter portion 67a is D3 and the outer diameter of the small-diameter portion 67b is D4, D3>D4, and D3-D4 is set to, for example, about 1 mm to 2 mm.

Further, when the total length of the female spline hole 67 is L5, the length of the large diameter portion 67a is L3, and the length of the small diameter portion 67b is L4, L5=L3+L4, and L3:L4=1:2. do. The cross-sectional shape of the spline convex tooth 69a of the female spline hole 67 is trapezoidal in the illustrated example, but may be a mountain-like shape with a convex rounded top.

According to the wheel bearing device of the present invention, the spline fitting between the stem portion 62 of the constant velocity universal joint 53 and the hub wheel 23 can be increased in diameter on the root side. As a result, deformation and wear on the root side can be prevented. In the spline fitting between the hub wheel 23 and the stem portion 62 of the constant velocity universal joint 53, even when sudden torque transmission occurs (when an EV vehicle starts moving, etc.), the portion where the contact surface pressure increases can be reinforced. and to suppress the occurrence of backlash at the fitting portion, and to alleviate the stick-slip noise generated between the inner member 21 (hub wheel 23) and the outer joint member 60 of the constant velocity universal joint 53 over a long period of time. can be done.

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By the way, in the above embodiment, the spline convex teeth 68a of the male spline shaft 65 extend along the axis of the stem portion 62, but as shown in FIG. It can be anything. Thus, when the torsion angle θ is given, the spline concave tooth 69b of the female spline hole 67 is strongly hit and a cushioning portion is generated. This twist .theta. is set, for example, from about 6' to 14'.

When the torsion angle θ of the spline convex teeth 68a of the male spline shaft 65 of the constant velocity universal joint 53 is assumed to be the positive rotation of the male spline shaft 65 when the vehicle is moving forward, the spline convex teeth 68a are set to the following values when the vehicle starts moving. By giving the spline convex teeth 68a of the male spline shaft 65 a torsion angle θ in the direction in which contact is released from the torsion of the male spline shaft 65 accompanying torque transmission, the contact pressure can be alleviated, Deformation and wear of the spline hole 67 can be suppressed.

Moreover, as shown in FIG. 5(b), the spline convex teeth 68a of the male spline shaft 65 may have an arc-shaped generatrix. In this manner, even when the arc shape is used, the contact of the spline convex tooth 68a can be set so as to be released from the torsion of the male spline shaft 65 due to torque transmission when the vehicle is started, so that the contact pressure can be reduced and the hub wheel 23 can be disengaged. Deformation and wear of the female spline hole can be suppressed.

The generatrix shape of the spline convex tooth 68a at the root portion on the mouth side of the male spline shaft 65 may be wavy. Such a corrugated shape increases the number of contact portions between the convex spline teeth 68a of the male spline shaft 65 and the concave spline teeth 69b of the female spline hole 67, thereby dispersing the load. Therefore, when the vehicle starts moving, the contact of the spline convex tooth 68a can be set to be released from the twist of the male spline shaft 65 due to torque transmission, the contact pressure can be reduced, and the female spline hole 67 of the hub wheel 23 can be deformed. and wear can be suppressed. In the case of the corrugated shape, it is possible to have three or more portions that strongly hit in the direction of rotation.

Further, in the hub wheel 23 of this wheel bearing device, a hardened portion 80 is formed in the opening of the female spline hole 67 on the inboard side. Various heat treatments such as laser hardening, induction hardening, and carburizing hardening can be employed as the heat hardening treatment. Induction quenching is a quenching method that applies the principle of heating a conductive object by inserting a portion necessary for quenching into a coil through which high-frequency current is flowing and generating Joule heat through electromagnetic induction. be. Carburizing and quenching is a method of infiltrating/diffusing carbon from the surface of a low-carbon material and then performing quenching. Laser hardening is a method of quenching and hardening by irradiating the surface of a component with a laser beam of high energy density. Laser irradiation devices include carbon dioxide lasers, solid-state lasers (YAG lasers), semiconductor lasers, and the like. The part that has undergone laser hardening expands into a convex shape and hardens.

That is, the inboard-side opening of the female spline hole 67 is a portion that is likely to be deformed or worn when a torque load is applied. Deformation and wear can be effectively prevented.

By the way, in the ASKUL module as shown in FIG. 3, the length (axial length) of the intermediate shafts 55 of the pair of (right and left) drive shafts may differ (different torsional rigidity). In the fixed type constant velocity universal joint, it is preferable to adjust the torsion angle θ of the male spline shaft 65 respectively. Further, in the ASKUL module as shown in FIG. 3, the spline convex teeth 68a of the left and right male spline shafts 65 may be of the same type or of different types.

Here, as the same type, all have a torsion angle θ, all have a circular arc-shaped generatrix, and all have a corrugated generatrix. As for the different types, the spline convex tooth shapes of the mouth-side root portions of the left and right constant velocity universal joints are different.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible. However, tapered rollers may also be used. In addition, as a wheel bearing device, the wheel bearing device has evolved from a structure that uses a double-row rolling bearing alone, which is called the first generation, to a second generation that has a vehicle body mounting flange integrally with the outer member. Furthermore, the third generation, in which the inner raceway surface is formed integrally with one of the double-row rolling bearings on the outer periphery of the hub ring having the wheel mounting flange integrally, and the constant velocity universal joint is integrated with the hub ring. Further, even the fourth generation has been developed in which the other inner rolling surface of the double-row rolling bearing is integrally formed on the outer circumference of the outer joint member that constitutes the constant velocity universal joint. Therefore, the present wheel bearing device may be a first to fourth generation wheel bearing device.

The male spline shaft 65 can be formed by rolling (cold working) using a rolling rack, but the female spline hole 67 cannot be formed by normal broaching because it has a stepped portion. is. Therefore, it becomes possible by performing vibration press working.

21 Inner member 22 Outer member 25 Ball 27 Outer raceway surface 28 Wheel mounting flange 29 Inner raceway surface 51A, 52B Drive shafts 53, 53A, 53B, 54A, 54B Constant velocity universal joints 55, 55A, 55B Intermediate shaft 60 Outer joint Member 61 Mouth 62 Stem 65 Male spline shaft 67 Female spline hole 67a Large diameter portion 67b Small diameter portion 68a Spline convex tooth 80 Hardened portion θ Torsion angle

Claims (8)

An outer member having a double-row outer raceway surface formed on its inner circumference, an inner member having an outer circumference formed with a double-row raceway surface facing the outer raceway surface, an outer member and an inner member The inner member has a hub ring, and the stem portion of the constant velocity universal joint is integrally connected to the hub ring via a spline connection. A bearing device for
The stem portion protrudes from the bottom portion of the mouth portion of the outer joint member of the constant velocity universal joint. The outer diameter of the side base is larger than the minimum diameter that satisfies the torque transmission capacity, and the other part of the male spline shaft is made smaller than the outer diameter of the mouth side base to satisfy the torque transmission capacity. A wheel bearing device characterized by: 2. A wheel bearing device according to claim 1, wherein a twist angle is imparted to the spline convex teeth of the mouth-side root portion of the male spline shaft. 2. A wheel bearing device according to claim 1, wherein the generatrix of the convex spline teeth at the mouth-side root portion of the male spline shaft is arcuate. 2. A wheel bearing device according to claim 1, wherein the generatrix shape of the convex spline teeth of the root portion on the mouth side of the male spline shaft is wavy. 5. The wheel bearing device according to any one of claims 1 to 4, wherein the inner peripheral portion of the inboard side opening of the female spline hole of the hub wheel is a heat-cured portion. A power transmission structure comprising a pair of left and right drive shafts,
Each drive shaft has a pair of constant velocity universal joints and an intermediate shaft that connects the constant velocity universal joints. A power transmission structure, wherein the constant velocity universal joint is connected to the wheel bearing device according to claim 2, and the torsion directions of the spline convex teeth of the mouth-side root portions of the left and right constant velocity universal joints are different. . A power transmission structure comprising a pair of left and right drive shafts,
Each drive shaft has a pair of constant velocity universal joints and an intermediate shaft that connects the constant velocity universal joints. A power transmission structure characterized in that the constant velocity universal joint is connected to the wheel bearing device according to claim 3, and the circular arc shapes of the spline convex teeth of the mouth-side base portions of the left and right constant velocity universal joints are symmetrical. . A power transmission structure comprising a pair of left and right drive shafts,
Each drive shaft has a pair of constant velocity universal joints and an intermediate shaft that connects the constant velocity universal joints. A constant velocity universal joint is connected to the bearing device for a wheel according to claim 1, and at least the convex spline teeth are provided with a twist angle, the generatrix shape of the convex spline teeth is an arc, and the convex spline teeth 1. A power transmission structure, characterized in that either a wave-shaped generatrix is adopted, and spline convex tooth shapes of mouth-side base portions of left and right constant velocity universal joints are made different.

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