JP2001113906A - Bearing unit for driving wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a small, lightweight structure with excellent durability and reliability. SOLUTION: A female spline part 16a formed at a center hole 15a of a hub 4a is engaged with a male spline part 14a formed at a drive shaft 12a attached to a housing part 13a that constitutes a constant velocity universal joint. A retaining ring 24 joins an outside locking groove 23 formed on the female spline part 16a and an inside locking groove 22 formed on the male spline part 14a to prevent the drive shaft 12a from coming off. The female spline part 16a and the male spline part 14a are hardened to prevent fretting abrasion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel drive bearing unit in which a constant velocity joint and a hub unit are integrated, and a drive wheel #FF vehicle (front engine front wheel) supported by an independent suspension type suspension. Driving car) front wheel, F
The rear wheels of the R vehicle (front-engine rear-wheel drive vehicle) and the RR vehicle (rear-engine rear-wheel drive vehicle) and all the wheels の of the 4WD vehicle (four-wheel drive vehicle) are rotatably supported by the suspension system. In addition, it is used to rotationally drive the drive wheels.

[0002]

2. Description of the Related Art In order to rotatably support wheels with respect to a suspension device, various bearing units are used in which an outer ring and an inner ring are rotatably combined via rolling elements. or,
In addition to supporting the drive wheels on an independent suspension,
The wheel drive bearing unit for rotating this drive wheel, in combination with a constant velocity joint, controls the rotation of the drive shaft regardless of the relative displacement between the differential gear and the drive wheel and the steering angle given to the wheel. It must be transmitted smoothly (with constant velocity) to the wheels. Conventionally, as a wheel drive bearing unit that can be configured to be relatively small and lightweight in combination with such a constant velocity joint, Japanese Patent Application Laid-Open No. 7-317754, Japanese Utility Model Application Laid-Open No. 61-94403, and US Pat. Description, International publication WO
DE 99/13232, German Patent Publication DE 1
What is described in 9700313 A1 gazette etc. is known.

FIG. 4 is a view showing one of them, which is shown in FIG.
3 shows an example of a conventional structure described in Japanese Patent Publication No. 3 (JP-A) No. 3 (Kokai) Publication. An outer ring 1 that is not rotated while supported by a suspension device in an assembled state to a vehicle has a first mounting flange 2 for supporting the suspension device on an outer peripheral surface, and a double-row outer ring raceway 3, 3 on an inner peripheral surface. Surface. A hub 4 is provided inside the outer ring 1.
Are supported concentrically with the outer ring 1. This hub 4
A second mounting flange 5 for supporting the wheel at a portion closer to the outer end of the outer peripheral surface (the end that is the outer side in the width direction when assembled to the automobile, the left end in FIGS. 1 to 3 and the right end in FIG. 4) A first inner raceway 6 is formed at the center. or,
A small-diameter stepped portion 7 is formed near the inner end of the outer peripheral surface of the hub 4 (the end that is located at the center in the width direction when assembled to an automobile, the right end in FIGS. 1 to 3 and the left end in FIG. 4). Small diameter step 7
Further, an inner ring 9 having a second inner ring track 8 formed on its outer peripheral surface is externally fitted and fixed. The rolling elements 10, 1 are arranged between the outer raceways 3, 3 and the first and second inner raceways 6, 8, respectively.
The hub 4 is rotatably supported on the inner side of the outer ring 1 by providing a plurality of rolls 0 for each of them. or,
Seal rings 11 and 11 are provided between inner peripheral surfaces of both ends of the outer ring 1 and outer peripheral surfaces of an intermediate portion of the hub 4 and inner ends of the inner ring 9, respectively.
The openings at both ends of the space where the is installed are closed.

A drive shaft 12 attached to a constant velocity joint is connected to the hub 4 so that the hub 4 can be driven to rotate. A base portion (left end in FIG. 4) of the drive shaft 12 has a housing portion 13 serving as an outer ring of the constant velocity joint.
Are integrally connected and fixed. This housing part 13
A track of a constant velocity joint is formed on the inner peripheral surface of the.
A male spline portion 14 is provided at an intermediate portion of the drive shaft 12, and the male spline portion 14 and a female spline portion 16 formed in a center hole 15 provided in the hub 4 are spline-engaged. Further, a retaining nut 18 is provided on a male screw portion 17 provided at a tip portion (right end portion in FIG. 4) of the drive shaft 12.
Are screwed and tightened, and the portion near the center of the outer end surface of the hub 4 is held down by the holding nut 18. In this state, the inner end surface of the inner race 9 that is fitted to the inner end of the hub 4 is pressed against the outer end surface of the housing portion 13.

When the wheel drive bearing unit constructed as described above is assembled to a vehicle, the outer ring 1 is supported on the suspension by the first mounting flange 2 and the second mounting flange 5
To fix the drive wheels to the hub 4. An outer end of a drive shaft (not shown), which is rotationally driven by an engine via a transmission, is connected to the housing portion 13.
Is spline-engaged inside the inner ring (not shown) for a constant velocity joint provided inside. When the automobile is running, the rotation of the inner ring for the constant velocity joint is transmitted to the drive shaft 12 via a plurality of balls and the housing portion 13, and the drive wheel fixed to the hub 4 by the drive shaft 12 is rotated. Drive rotationally.

When the driving wheels are driven to rotate as described above, the torque is transmitted from the drive shaft 12 to the hub 4 by the male spline portion 14 and the female spline portion 16.
In addition to the spline engagement portion, the friction engagement portion between the holding nut 18 and the outer end surface of the hub 4 and the friction engagement portion between the inner end surface of the inner race 9 and the outer end surface of the housing portion 13 are also provided. Done. For this reason, the torque transmitted by the spline engaging portion is limited, and the male spline portion 14 and the female spline portion 16 constituting the spline engaging portion are rarely rubbed finely. Therefore, conventionally, the female spline portion 16 is not particularly hardened and hardened.
No fretting wear occurred on the surface of No. 16.

[0007]

In recent years, for the purpose of cost reduction by reducing parts costs and assembly costs, and miniaturization and weight reduction by miniaturization of parts, coupling of a component member of a constant velocity joint and a hub has been performed. It is possible to use a retaining ring in place of the retaining nut, as described in the aforementioned International Publication WO 99/132.
No. 32 has been proposed. When the components of the constant velocity joint and the hub are connected by the retaining ring, it is difficult to strongly press the components of the constant velocity joint and the hub in the axial direction. It is also difficult to make a strong frictional engagement between the side surface of the retaining ring and the component member or hub of the constant velocity joint. Therefore,
In the case where the coupling structure using the retaining ring is adopted, it is necessary to transmit most of the torque from the constant velocity joint to the hub by the spline engagement portion.

For this reason, a large torque is applied to the spline engaging portion when the vehicle is running. As a result, even when the spline engagement portion is set in a fitting state with an interference, fretting wear is likely to occur in the spline engagement portion based on the minute vibration generated in the spline engagement portion.
In particular, when the surface of the female spline portion 16 is not quenched and hardened and remains soft as in the conventional structure, the fretting wear is not negligible, and the durability of the wheel drive bearing unit is sufficiently improved. It becomes difficult to secure.
The wheel drive bearing unit of the present invention has been invented in view of such circumstances.

[0009]

According to the wheel drive bearing unit of the present invention, a first mounting flange for mounting to a suspension device is provided on an outer peripheral surface of the wheel drive bearing unit, similarly to the above-described conventional wheel drive bearing unit. A double-row outer raceway on the surface, an outer race respectively having an outer raceway, a second mounting flange for supporting the wheel at a portion near the outer end of the outer peripheral surface, and a first inner raceway at the same central portion, respectively, Similarly, a hub in which an inner ring having a second inner raceway formed on its outer peripheral surface near the inner end is externally fitted and fixed, and a plurality of hubs are respectively rotated between the outer raceways and the first and second inner raceways. A rolling element movably provided;
And a housing portion forming an orbit of the constant velocity joint on an inner peripheral surface thereof and serving as an outer ring of the constant velocity joint. The housing portion or a member connected to the housing portion is spline-engaged with the hub or a member connected to the hub, so that torque from the housing portion to the hub can be transmitted.

[0010] In particular, in the wheel drive bearing unit of the present invention, a retaining ring bridged between the housing portion or a member connected to the housing portion and the hub or a member connected to the hub is provided. The spline engagement portion provided between the housing portion or the member connected to the housing portion and the hub or the member connected to the hub is prevented from shifting in the axial direction. Then, the portions of the female spline groove and the male spline groove that constitute the spline engaging portion, which engage with each other, are hardened and hardened by at least a part of the spline engaging portion.

[0011]

In the case of the wheel drive bearing unit of the present invention constructed as described above, the coupling between the hub and the housing part, which is a component of the constant velocity joint, is performed by a retaining ring, so that the cost of parts and assembly can be reduced. Cost reduction through cost reduction,
In addition, a structure that can be reduced in size and weight by downsizing components can prevent the occurrence of fretting wear in the spline engagement portion.

[0012]

FIG. 1 shows a first embodiment of the present invention. The outer ring 1 which does not rotate while being supported by the suspension device has a first mounting flange 2 for supporting the suspension device on the outer peripheral surface, and a double-row outer ring raceway 3, 3 on the inner peripheral surface.
Respectively. A hub 4 a is arranged concentrically with the outer ring 1 on the inner diameter side of the outer ring 1. Further, a second mounting flange 5 for supporting the wheel is formed at a portion near the outer end of the outer peripheral surface of the hub 4a, and a first inner raceway 6 is formed at the center similarly. The first inner raceway 6 may be formed directly on the outer peripheral surface of the hub 4a, or may be formed on the outer peripheral surface of a separate inner race fitted to the hub 4a. A small-diameter stepped portion 7 is formed at a portion near the inner end of the main body portion 19 of the hub 4a, and an inner ring 9 having a second inner raceway 8 formed on the outer peripheral surface thereof is fitted to the small-diameter stepped portion 7. ing. Then, the inner ring 9 is fixed to the main body portion 19 by a caulking portion 20 formed by caulking and expanding a portion of the inner end of the main body portion 19 protruding from the inner end surface of the inner ring 9 outward in the diameter direction. ing. A plurality of rolling elements 10, 10 are provided between the outer raceways 3, 3 and the first and second inner raceways 6, 8, respectively, so as to freely roll, and are provided inside the outer race 1. The hub 4a is rotatably supported.

Further, seal rings 11 are provided between inner peripheral surfaces of both ends of the outer race 1 and outer peripheral surfaces of an intermediate portion of the hub 4a and inner ends of the inner race 9, respectively. The openings at both ends of the space where the moving bodies 10 and 10 are installed are closed. Further, the cap 21 is fitted and fixed to the outer end opening of the hub 4a to close the outer end opening, thereby preventing foreign matter such as rainwater from entering the spline engaging portion described later from the outer end. Preventing.

Further, a female spline groove is formed in one half (the right half in FIG. 1) of the center hole 15a of the hub 4a, so that this one half is a female spline portion 16a. Further, such a hub 4a and a housing portion 13a serving as an outer ring of a constant velocity joint are combined to constitute a wheel driving rolling bearing unit. In the case of this example, the base end (inner end) of the drive shaft 12a is integrally connected to the outer end surface of the housing portion 13a. This drive shaft 12
By forming a male spline groove in a portion of the outer peripheral surface except for a portion near the base end, the portion is formed into a male spline portion 14.
a.

In the case of the present invention, a portion where the female spline portion 16a is formed on the inner peripheral surface of the center hole 15a (FIG. 1).
1 and a portion where the male spline portion 14a is formed on the outer peripheral surface of the drive shaft 12a (FIG. 1).
The part indicated by the oblique lattice is hardened and hardened. For this purpose, for example, the hub 4a is connected to S55C or S53C,
Alternatively, it is made of a steel material corresponding to these, and a quench hardening treatment such as an induction heat treatment is applied to the portion to be quenched and hardened. Similarly, for the drive shaft 12a, the male spline portion 14a is hardened and hardened. The female spline portion 16a and the both cases of the male spline portion 14a, the hardness H _R C of at the surface after quenching 59-6
5, and the effective hardened layer depth is 1 to 3 mm. In the case of the present embodiment, the outer peripheral surface of the hub 4a is also quenched and hardened by hanging from the base end of the second mounting flange 5 to the small-diameter stepped portion 7.

An inner locking groove 22 is formed on the entire outer periphery of the drive shaft 12a near the outer end thereof. or,
An outer locking groove 23 is formed over the entire circumference at a position matching the inner locking groove 22 on the inner peripheral surface of the intermediate portion near the outer end of the center hole 15a. The annular retaining ring 24 is attached to both the inner and outer locking grooves 22 and 23 in such a manner that the retaining ring 24 extends over the both locking grooves 22 and 23.

The retaining ring 24 is made of a resilient metal such as spring steel or stainless spring steel, and is formed by forming a wire having a circular cross section into a substantially C-shaped cutout annular shape, so that the diameter thereof can be elastically expanded and contracted. The outer diameter of the retaining ring 24 in the free state is larger than the diameter of the largest inscribed circle of the female spline portion 16a (the tip circle of the female spline portion 16a) in the center hole 15a. . The diameter of the groove bottom of the inner locking groove 22 and the diameter of the groove bottom of the outer locking 23 are
4 is restricted so as to extend between the inner and outer locking grooves 22 and 23.

That is, the diameter of the groove bottom of the inner locking groove 22 is equal to or less than a value obtained by subtracting twice the diameter of the wire constituting the retaining ring 24 from the diameter of the largest inscribed circle of the female spline portion 16a. And Such a regulation is based on the above-mentioned retaining ring 24.
Is pushed down to the bottom of the inner locking groove 22,
This is necessary so that the drive shaft 12a can be inserted into the female spline portion 16a together with the retaining ring 24. The diameter of the groove bottom of the outer locking groove 23 is the diameter of the largest circumscribed circle of the male spline portion 14a of the drive shaft 12a (the tooth tip circle of the male spline portion 14a), and forms the retaining ring 24. It is less than a value obtained by adding twice the diameter of the wire. Such a regulation is performed when the diameter of the retaining ring 24 is elastically widened and the inner peripheral edge portion of the retaining ring 24 and the inner locking groove 22 are fixed.
It is necessary to engage with. Therefore, preferably,
With the outer peripheral edge of the retaining ring 24 and the groove bottom of the outer locking member 23 in contact with each other, the retaining ring 24 is positioned at the center in the diameter direction of the engaging portion between the female spline portion 16a and the male spline portion 14a. The diameter of the groove bottom of the outer locking groove 23 is regulated so as to exist.

In order to regulate the dimensions of the inner and outer locking grooves 22, 23 and the retaining ring 24 as described above, the retaining ring 2
When the drive shaft 12a is inserted into the center hole 15a in a state where the hub 4a is mounted on the inner locking groove 22, the hub 4a
And the drive shaft 12a can be connected inseparably. That is, when connecting the hub 4a and the drive shaft 12a, the drive shaft 12a is inserted into the center hole 15a in a state where the retaining ring 24 is attached to the inner locking groove 22, and from the inside to the outside. 1 Insert from right to left. By this insertion work, the retaining ring 24 is guided by the inner peripheral surface of the caulked portion 20 and the conical concave guide surface 25 provided adjacent to the inner end of the center hole 15a, and the outer diameter thereof is elastically adjusted. And pushed into the center hole 15a.

With the inner locking groove 22 and the outer locking groove 23 aligned with each other, the diameter of the retaining ring 24 is determined by the outer peripheral edge of the retaining ring 24 and the bottom surface of the outer locking groove 23. Until it comes into contact with it. And
In a state where the diameter of the retaining ring 24 is elastically widened in this manner, the retaining ring 24 is engaged with the inner and outer locking grooves 22, 2 and 2.
3 and the drive shaft 1
2a is prevented from falling out of the center hole 15a, and the hub 4a and the drive shaft 12a are inseparably connected. still,
The inclination angle of the guide surface 25 with respect to the axial direction of the hub 4a is preferably 30 degrees or less so that the retaining ring 24 can pass through the guide surface 25 smoothly. The widths of the inner and outer locking grooves 22 and 23 need to be equal to or larger than the diameter of the wire constituting the retaining ring 24. The difference between the width and the diameter is made as small as possible. The reason for this is that both the inner and outer locking grooves 22, 23 and the retaining ring 2 are used.
This is for suppressing the rattling of the connecting portion due to No. 4.

In the case of this embodiment, the drive shaft 12a and the housing 1 are mounted on the outer peripheral surface of the intermediate portion of the drive shaft 12a.
A seal ring 26 having an X-shaped cross section is provided between a portion between the inner ring 3a and the inner peripheral surface of the inner end of the hub 4a. It was made into an annular shape by using an elastic material such as an elastomer such as rubber.
The seal ring 26, together with the cap 21, substantially completely seals the spline engagement portion between the drive shaft 12a and the center hole 15a to prevent foreign matter such as rainwater containing dust from entering the spline engagement portion. To prevent the spline engagement portion from rusting or promoting the wear of the engagement portion. A gap 27 is interposed between the caulked portion 20 formed at the inner end of the hub 4a and the outer end surface of the housing 13a of the drive shaft 12a. Therefore, during operation of the wheel drive axle unit of this example, even if relative movement in the circumferential direction occurs based on elastic deformation at the time of torque load, the caulking portion 20 and the outer end surface of the housing portion 13a are in contact with each other. There is no rubbing, and no abnormal noise due to rubbing occurs. Further, a locking groove 28 for locking the outer end of a dustproof boot (not shown) is formed on the outer peripheral surface of the inner end of the housing portion 13a.

In the case of the wheel drive bearing unit of the present invention constructed and assembled as described above, the torque transmission between the drive shaft 12a and the hub 4a is performed by the male formed on the outer peripheral surface of the drive shaft 12a. The spline portion 14a and the center hole 1
This is performed only at the spline engagement portion with the female spline portion 16a formed on the inner peripheral surface of 5a. Therefore, there is a possibility that the female spline groove and the male spline groove constituting the spline engaging portion are finely rubbed based on the minute vibration generated in the spline engaging portion during the torque transmission. In the case of the wheel drive bearing unit of the present invention, the portion where the female spline portion 16a is formed on the inner peripheral surface of the center hole 15a and the male spline portion 1 on the outer peripheral surface of the drive shaft 12a.
4a is formed with each of these spline portions 16a,
Since the hardening and hardening are performed over the entire length of 14a over the entire circumference, fretting wear is less likely to occur on the spline engagement portion regardless of the friction generated as described above. If a lubricant such as grease is applied to the spline engagement portion, wear of the spline engagement portion can be prevented more effectively.

Further, in the case of the wheel drive bearing unit of the present invention, the separation between the drive shaft 12a and the hub 4a is prevented.
Retaining ring 24 spanning both inner and outer locking grooves 22, 23
It is aimed at by. This retaining ring 24 formed in a partially annular shape
Can be made of a metal material having sufficient strength, such as spring steel or stainless steel spring, so that the separation can be reliably prevented and the reliability of the wheel drive bearing unit can be ensured. Further, a seal ring 26 is provided between the drive shaft 12a and the hub 4a.
Since the spline engagement portion between the a and the center hole 15a is shielded from the external space, the wear can be prevented more reliably.

FIG. 2 shows a second embodiment of the present invention.
An example is shown. In the case of this example, the outer end of the housing portion 13b serving as the outer ring of the constant velocity joint is spline-engaged with the inner end of the hub 4b via the auxiliary ring 29. Of the inner and outer peripheral surfaces of the auxiliary ring 29 formed in a short cylindrical shape, an inner diameter side female spline portion 30 is provided on the inner peripheral surface,
An outer diameter side male spline portion 31 is formed on the outer peripheral surface. Such an auxiliary ring 29 allows the inner diameter side male spline portion 32 and the inner diameter side female spline portion 30 formed on the inner end portion outer peripheral surface of the hub 4b to be spline-engaged without looseness. In, it is assembled. Then, in this state, the inner end surface of the auxiliary ring 29 is suppressed by the caulking portion 20 formed at the inner end of the hub 4b, and the auxiliary ring 29 is attached to the inner end of the hub 4b.
Fixed without rattling.

As described above, the inner end surface of the auxiliary ring 29 is held down by the caulking portion 20, and the auxiliary ring 29
Each of the rolling elements 10, 10 constituting the bearing unit is held in a state in which the inner end surface of the inner ring 9 externally fitted to the small diameter
The dimensions of each part are regulated so that an appropriate preload is applied to the parts. In the case of the present example, the auxiliary ring 29
It was converted, using through-hardened steel such as SUJ2, not only the inner diameter side female spline portion 30 and the outer diameter side male spline portion 31, to the core portion, baked to hardness of about H _R C 60 to 64 placed cure are doing. However, the entire surface of the auxiliary ring 29 may be quenched by induction hardening or carburizing quenching using a material other than SUJ2. Alternatively, the quenching process of the auxiliary ring 29 may be performed so that the inner diameter side female spline portion 30 and the outer diameter side male spline portion 3 are not deformed by the load applied at the time of caulking the caulking portion 20.
Only 1 may be performed by induction hardening.

On the other hand, an outer female spline portion 33 formed on the inner peripheral surface of the outer end of the housing portion 13b is spline-engaged with the outer male spline 31 formed on the outer peripheral surface of the auxiliary ring 29. ing. In the case of this example, the housing portion 13b forms an intermediate material having a basic shape by subjecting a pipe material to hot forging or cold forging. That is, the forging is performed on the pipe material manufactured by S55C or S53C or the like to form the intermediate material, and the intermediate material is appropriately cut or ground to form the housing portion 13b. . On the other hand, conventionally, a solid bar (bar material) is used as a material for forming a basic shape of a housing portion constituting a constant velocity joint, and the solid bar is subjected to hot forging, or Other articles were welded to the solid bar material that had been subjected to hot forging. In contrast to such a conventional method, in the case of this example, by using a pipe material as described above,
We are trying to reduce costs.

An engagement groove 34 is formed on the inner peripheral surface of the inner half of the housing portion 13b so as to orbit a ball constituting a constant velocity joint. On the other hand, the outer diameter side female spline portion 33 is formed on the inner peripheral surface of the outer end portion. And, as described above, the outer diameter side female spline portion 33,
An outer diameter side male spline portion 31 formed on the outer peripheral surface of the auxiliary ring 29 is spline-engaged. In the case of this example, as shown by the oblique lattice in FIG. 2, a hardened hardened layer is formed on the inner peripheral surface of such a housing portion 13b by an induction hardening process. In the illustrated example, the hardened hardened layer is formed on the entire inner peripheral surface of the housing portion 13b.
It suffices if they are formed in four portions and the outer diameter side female spline portion 33 portion. Anyway, the surface hardness of the quench hardened layer is set to H _R C 59 to 65, effective case depth is 1-4
mm.

As described above, the splines were engaged with each other.
A retaining ring 24a is provided between the outer diameter side female spline portion 33 and the outer diameter side male spline portion 31 so that the housing portion 13b and the auxiliary ring 29 are not separated. That is, the above-described retaining ring 24a, which is formed by hardening a spring steel such as SK5 or the like and hardened, is formed on the outer peripheral surface of the auxiliary ring 29 over the entire periphery of the auxiliary ring 29. The groove 22a and the housing portion 13b
Outer locking groove 23 formed over the entire inner circumferential surface of the outer end portion
a to prevent the housing portion 13b and the auxiliary ring 29 from moving in the axial direction.

The retaining ring 24a is connected to the inner locking groove 22a.
When the retaining ring 24a is bridged between the retaining ring 24a and the outer locking groove 23a, a portion of the retaining ring 24a closer to the inner periphery is locked in the inner locking groove 22a in advance. In this state (free state), the outer diameter of the retaining ring 24a is larger than the inner diameter of the outer female spline portion 33 formed on the inner peripheral surface of the outer end of the housing portion 13b. From this state, in order to connect the housing portion 13b and the auxiliary ring 29, the housing portion 13
When the outer end of the housing portion 13b is externally fitted to the auxiliary ring 29, the tapered portion 35 formed on the outer edge of the outer end opening of the housing portion 13b reduces the diameter of the retaining ring 24a while the outer end of the housing portion 13b. Covers the auxiliary ring 29. The outer peripheral edge of the retaining ring 24a is formed in the outer locking groove 2.
In a state aligned with 3a, the retaining ring 24a elastically returns and engages with the outer locking groove 23a. In this state, the housing portion 13b and the hub 4b are connected via the auxiliary ring 29.

Further, the outer peripheral surface of the hub 4b is formed from a portion where the first inner raceway 6 is formed from the base end of the second mounting flange 5 and a small-diameter stepped portion 7 on which the inner race 9 is fitted. Up to １ ／ to ／ of the entire length of the side male spline portion 32 is quenched and hardened as shown by the oblique lattice in FIG.
The portion forming the caulked portion 20 at the inner end of the hub 4b is not hardened, so that the caulked portion 20 can be formed.

In the case of the present embodiment having such a configuration, the torque transmission between the housing portion 13b and the hub 4b is performed by the internal female spline portion 30 formed on the inner and outer peripheral surfaces of the auxiliary ring 29, An outer diameter side male spline portion 31;
This is performed only at the spline engagement portion between the inner diameter side male spline portion 32 formed on the outer peripheral surface at the inner end portion of the hub 4b and the outer diameter side female spline portion 33 formed at the inner peripheral surface at the outer end portion of the housing portion 13b. Therefore, there is a possibility that the female spline groove and the male spline groove constituting each of these spline engagement portions are finely rubbed based on the minute vibration generated in each of these spline engagement portions during the torque transmission. In particular, the outer diameter side female spline section 33 and the outer diameter side male spline section 31
The outer diameter side spline engaging portion, which is an engaging portion with the outer ring, is not fastened and fixed in the axial direction, and there is an axial gap between the retaining ring 24a and each of the locking grooves 22a, 23a. Therefore, fretting wear due to minute vibration in the axial direction is likely to occur. In the case of this example, each of the above spline portions 30 to
Since the portion where 33 is formed is hardened over its entire length or a part of the axial direction over the entire circumference,
Regardless of the rubbing that occurs as described above, fretting wear is less likely to occur in the spline engagement portion. Other configurations and operations are the same as in the case of the above-described first example.

FIG. 3 shows a third embodiment of the present invention.
An example is shown. In the case of this example, the auxiliary ring 29 (FIG. 2) is omitted from the structure of the above-described second example, and instead, a cylindrical extension 36 is provided on the inner end surface of the inner ring 9a in a state of projecting in the axial direction. The inner ring 9a is provided concentrically with the main body. Then, an inner diameter side female spline portion 30 is formed on the inner peripheral surface of the extension portion, and an outer diameter side male spline groove 31 is formed on the outer peripheral surface. In this case, the inner ring 9a and the extension 36 are made of S55C or S53C or a steel material corresponding thereto, and the entire surface is subjected to a quench hardening treatment such as an induction heat treatment. Hardness in the surface after quenching is a H _R C 59 to 65, the effective hardened layer depth is a 1 to 3 mm. Other configurations and operations are the same as those of the above-described second example.

[0033]

Since the present invention is constructed and operates as described above, it is possible to realize a wheel drive bearing unit which is small, lightweight, low-cost and has excellent durability.

[Brief description of the drawings]

FIG. 1 is a half-cut side view showing a first example of an embodiment of the present invention.

FIG. 2 is a half-cut side view showing the second example.

FIG. 3 is a half-cut side view showing the third example.

FIG. 4 is a half-cut side view showing an example of a conventional structure.

[Description of Signs] 1 outer ring 2 first mounting flange 3 outer ring track 4, 4a, 4b hub 5 second mounting flange 6 first inner ring track 7 small-diameter stepped portion 8 second inner ring track 9, 9a inner ring 10 rotation Moving body 11 Seal ring 12, 12a Drive shaft 13, 13a, 13b Housing section 14, 14a Male spline section 15, 15a Center hole 16, 16a Female spline section 17 Male screw section 18 Suppressing net 19 Main body section 20 Caulking section 21 Cap 22, 22a Inner locking groove 23, 23a Outer locking groove 24, 24a Retaining ring 25 Guide surface 26 Seal ring 27 Gap 28 Locking groove 29 Auxiliary ring 30 Internal female spline section 31 External male spline section 32 Internal male spline section 33 Outer Diameter Female Spline 34 Engagement Groove 35 Tapered 36 Extended

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16D 3/20 F16D 1/02 M

Claims (1)

[Claims] 1. An outer ring having a first mounting flange for mounting to a suspension device on an outer peripheral surface, a double row of outer ring raceways on an inner peripheral surface, and a wheel supported on a portion of the outer peripheral surface near an outer end. A second mounting flange, also provided with a first inner raceway in the center portion, respectively, and a hub in which an inner race having a second inner raceway formed on the outer peripheral surface thereof is similarly fixed to a portion near the inner end, and a hub, A plurality of rolling elements provided so as to freely roll between each of the outer ring raceways and the first and second inner raceways, and a constant velocity joint track formed on an inner peripheral surface thereof; And a housing part that becomes an outer ring of
A sprocket engagement between the housing portion or the member connected to the housing portion and the hub or the member connected to the hub makes a wheel drive bearing unit capable of transmitting torque from the housing portion to the hub freely. In
By the retaining ring bridged between the housing part or the member connected to the housing part and the hub or the member connected to the hub, the retaining part is connected to the housing part or the member connected to the housing part and the hub or the hub. The spline engagement portion provided between the spline engagement portion and the coupled member is prevented from moving in the axial direction, and the female spline groove and the male spline groove constituting the spline engagement portion are engaged with each other. A wheel drive bearing unit, wherein at least a part of the spline engagement portion is hardened and hardened.