JP2002036810A - Bearing unit for driving wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a spline engagement part of a spline shaft with a spline hole from emitting cogging sounds at the time of torque cariation by suppressing the relative displacement in the rotating direction of a hub and a drive shaft member. SOLUTION: A male side fitting member 41 is provided in the middle of the drive shaft member 18b while a female fitting member 42 is furnished at the inner end of the hub 4a, wherein the male fitting member 41 is equipped with a fine surface unevenness by means of knurling process, and the obtained peripheral surface is hardened in quenching. The male fitting member 41 and female fitting member 42 are fitted together by pressure in association with the combination of the hub 4a with the drive shaft member 18b.

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. FIG. 3 shows a general automobile wheel drive device in which the wheel supporting bearing unit 1 and the constant velocity joint 2 are combined for such a purpose.

[0003] The above-mentioned wheel supporting bearing unit 1 includes an outer ring 3.
A hub 4 and an inner ring 5 are provided on the inner diameter side of a plurality of rolling elements 6, 6.
It is rotatably supported via a. Outer ring 3 of these
Is fixedly connected to a knuckle 8 (see FIG. 4 described later) constituting a suspension device by a first flange 7 provided on an outer peripheral surface thereof, and does not rotate during use. In addition, the outer ring 3
Are provided on the inner peripheral surface thereof, and the hub 4 and the inner ring 5 are rotatably supported concentrically with the outer ring 3 on the inner diameter side of the outer ring 3.

[0004] Of these, the hub 4 is located near the end of the outer peripheral surface (in the axial direction, the outer side in the width direction of the vehicle when assembled to the vehicle. The same applies throughout the present specification; the left side of each drawing). A second flange 10 for supporting the wheel is provided. Further, a first inner raceway 11 is formed at an intermediate portion of the outer peripheral surface of the hub 4, and the inner raceway 11 is also formed in the same direction (in the axial direction, the center of the vehicle in the width direction of the vehicle when assembled to the vehicle. Right side of each figure.) Small-diameter step 1 formed near the end
2, the inner ring 5 having a second inner ring track 13 formed on its outer peripheral surface is externally fitted and fixed. A spline hole 14 is provided in the center of the hub 4.

On the other hand, the constant velocity joint 2 includes a constant velocity joint outer ring 15, a constant velocity joint inner ring 16, and a spline shaft 17. The constant-velocity joint outer race 15 and the spline shaft 17 constitute a drive shaft member 18. That is, the spline shaft 17 is provided at the outer end of the drive shaft member 18 and is freely engageable with the spline hole 14. The constant velocity joint outer ring 15 is provided at the inner end of the drive shaft member 18. Is provided. Outer engagement grooves 19 are formed at a plurality of circumferential positions on the inner circumferential surface of the outer race 15 for constant velocity joints, respectively, in a direction perpendicular to the circumferential direction. The inner race 16 for the constant velocity joint, which constitutes the constant velocity joint 2, has a second spline hole 20 at the center portion and an inner spline hole at a portion of the outer peripheral surface which is aligned with the outer engagement grooves 19, 19. Engagement grooves 21, 21
Are formed in a direction perpendicular to the circumferential direction.
The balls 22, 22 are inserted between the inner engagement grooves 21, 21 and the outer engagement grooves 19, 19,
In the state held by 3, it is provided so as to roll freely along each of the engagement grooves 21, 19. In addition, the above constant velocity joint 2
The shape and the like of each component are the same as in the case of the well-known Zeppa type constant velocity joint, and are not related to the gist of the present invention.

[0006] The constant velocity joint 2 as described above and the wheel supporting bearing unit 1 as described above are connected to the spline shaft 17.
Into the spline hole 14 of the hub 4 from the inside to the outside in the axial direction. And the spline shaft 17
A nut 25 is screwed into a male screw part 24 provided at a portion protruding from the outer end surface of the hub 4 at the outer end of the hub 4 and further tightened to be fixedly connected to each other. In this state, the inner ring 5
Since the inner end surface of the inner ring 5 abuts on the outer end surface of the outer ring 15 for a constant velocity joint, the inner ring 5 is not displaced in the direction of coming out of the small-diameter step portion 12. At the same time, each rolling element 6,
6 is given an appropriate preload.

Further, when assembled to the suspension system of the automobile, the male spline portion 27 provided at the outer end of the drive shaft 26 is inserted into the second spline hole 20 provided at the center of the inner ring 16 for the constant velocity joint. Are spline-engaged. Then, a retaining ring 29 locked in a locking groove 28 formed over the entire outer peripheral surface of the outer end portion of the male spline portion 27 is formed at the outer peripheral edge of the outer end opening of the second spline hole 20. The male spline portion 27 is prevented from falling out of the second spline hole 20 by engaging with the locking step portion 30.
The inner end of the drive shaft 26 is fixedly connected to the center of the trunnion of a tripod constant velocity joint (not shown) provided on the output shaft of a differential gear (not shown).

US Pat. No. 4,881,842 describes a wheel drive bearing unit as shown in FIG. In the case of the second example of the conventional structure shown in FIG.
The hub 4 is rotatably supported inside the outer ring 3 fixed to the knuckle 8 by rolling elements 6, 6 arranged in double rows.
The spline hole 1 formed in the center of the hub 4
4, the spline shaft 17 of the drive shaft member 18a is spline-engaged. On the outer end surface of the spline shaft 17, a locking portion 31 for locking a tool for drawing the spline shaft 17 into the spline hole 14 is formed. A locking groove 32, which is an inner engaging portion, is formed on a portion of the spline shaft 17 near the front end of the outer peripheral surface, and is provided on a portion of the inner peripheral surface of the hub 4 facing the locking groove 32. The spline shaft 17 is connected to the hub 4 by hanging the retaining ring 33 over the locking step 35 which is an outer engaging portion.
Prevents getting out of. In this state, the elastic ring 34 is elastically compressed between the hub 4 and the outer race 15 for the constant velocity joint of the drive shaft member 18a.
An inner ring 5 having a second inner raceway 13 formed on the outer peripheral surface thereof is fitted around the inner end of the hub 4 at the inner end thereof, and the inner end of the hub 4 is more axially located than the inner end surface of the inner race 5. A retaining ring 37 is locked in a locking groove 36 formed on the outer peripheral surface of a portion protruding inward in the direction. The retaining ring 37 suppresses the inner end surface of the inner ring 5 to prevent the inner ring 5 from shifting in the axial direction.

According to the second example of the conventional structure described in the above-mentioned US Pat. No. 4,881,842, the joining operation between the wheel supporting bearing unit 1a and the constant velocity joint 2a can be easily performed. That is, in the case of the first example of the conventional structure shown in FIG. 3, the nut 25 is screwed into the male screw portion 24 of the spline shaft 17 in order to connect the wheel supporting bearing unit 1 and the constant velocity joint 2. In addition, further tightening and laborious work are required. As described above, when the operation of connecting the wheel supporting bearing unit 1 and the constant velocity joint 2 is troublesome,
The cost required for assembling the wheel drive bearing unit is increased. In addition, the provision of the male screw portion 24 and the nut 25 increases the size and weight of the wheel drive bearing unit. On the other hand, in the case of the second example of the conventional structure described above, the wheel supporting bearing unit 1a and the constant velocity joint 2a
Can be connected only by bridging the retaining ring 33 between the inner peripheral surface of the outer end of the hub 4 and the outer peripheral surface of the outer end of the spline shaft 17. The joint work with the speed joint 2a can be easily performed, and the cost required for assembly can be reduced.

However, in any of the above-mentioned conventional structures, a spline composed of a male spline portion 38 formed on the outer peripheral surface of the spline shaft 17 and a female spline portion 39 formed on the inner peripheral surface of the spline hole 14 is used. There is a possibility that a minute gap may be generated between the circumferentially opposed side surfaces of the teeth of the engaging portion 40 in a neutral state (a state in which torque is not transmitted between the spline shaft 17 and the hub 4). Torque is transmitted between the spline shaft 17 and the hub 4 via the spline engagement portion 40. As described above, a minute gap is formed between the side surfaces of the teeth of the male and female spline portions 38 and 39. When a gap is generated, the male and female spline portions 38 and 39 relatively displace relative to each other in the circumferential direction even when the vehicle is accelerated or decelerated. Then, based on the relative displacement, the side surfaces of the teeth of the two spline portions 38 and 39 come into strong contact with each other in a shocking manner, so that an occupant of the automobile may generate an unpleasant rattle. The first of the conventional structure shown in FIG.
In the case of the example, by tightening the nut 25, the hub 4 and the inner ring 5, the nut 25 and the drive shaft member 1
Since a large frictional force acts between them, they do not come into strong contact with each other in an impact, and a particularly large rattle is rarely generated. On the other hand, in the case of the second example of the conventional structure shown in FIG. 4, no countermeasure is taken since little frictional force for preventing the relative rotation between the spline shaft 17 and the hub 4 acts. In such a case, loud rattling noise is likely to occur.

Therefore, when the above-described conventional structure is implemented, for example, each tooth of the male spline portion 38 is moved with respect to the center axis of the spline shaft 17 (for example, about 10 minutes).
It has been considered to form a shape having a twist angle so as to be inclined. In this case, the male spline portion 38
The teeth of the female spline portion 39 are formed parallel to the center axis of the spline hole 14 without giving a twist angle to the teeth of the female spline portion 39 to be spline-engaged. The male spline portion 38 is formed by rolling the outer peripheral surface of the spline shaft 17 into a predetermined shape having a twist angle as described above, and then performing an induction hardening process. Cure the surface. On the other hand, the female spline portion 39 is formed in a predetermined shape that does not give a twist angle as described above by performing broaching on the inner peripheral surface of the spline hole 14, and then the unquenched state is obtained. Leave it alone.

If the male spline section 38 is formed into a shape having a twist angle as described above, the male and female spline sections are formed in a state where the wheel supporting bearing unit 1a and the constant velocity joint 2a are connected. Since the side surfaces of the teeth 38 and 39 are pressed against each other at both ends in the axial direction, it is possible to prevent the above-described rattling noise from occurring when the automobile is running. On the other hand, the teeth of the male and female splines 38 and 39 are formed in parallel with the axial direction, and the spacing between the teeth adjacent to each other in the circumferential direction is regulated. It is also conceivable to adopt a structure in which the side surfaces of the teeth 38 and 39 are strongly pressed together over the entire axial length. In the case of such a structure, the occurrence of the rattling noise can be prevented, but in this case, the shape and dimensional accuracy must be regulated very strictly, which not only increases the cost but also increases the spline. The force (press-fit) required to press-fit the spline shaft 17 into the hole 14 becomes excessive, which is not preferable. On the other hand, as described above, the male spline portion 38 is
In order to prevent the occurrence of the rattling noise by forming a shape having a twist angle, the spline portions 38 and 39 are used.
Since the side surfaces of the respective teeth press against each other only at the both ends in the axial direction, the pressure input can be reduced.

[0013]

In the case of the second example of the conventional structure shown in FIG. 4, the connecting work between the hub 4 and the drive shaft member 18a can be easily performed, but the male spline section 38 and the female spline section 39 are not required. It is difficult to sufficiently secure the durability of the spline engagement portion 40 of the first embodiment. The reason will be described below. When the coupling structure using the retaining ring 33 is adopted as in the second example of the conventional structure described above, the transmission of torque from the drive shaft member 18a to the hub 4 is mainly performed by the male spline portion 38 and the female spline portion. Spline engagement part 4 with 39
Perform at 0. For this reason, a large torque is applied to the spline engagement portion 40 when the automobile is running, and fretting wear is likely to occur in the spline engagement portion 40.

That is, in the case of suppressing the rattling noise in the second example of the conventional structure described above, the female spline teeth forming the female spline portion 39 are formed parallel to the center axis of the hub 4 and the male spline teeth are formed. The male spline teeth forming the spline portion 38 are formed in a direction having a twist angle with respect to the direction of the center axis of the drive shaft member 18a, and the spline engagement portion 40 between the two spline portions 38, 39 is formed. Make the fitting state with the interference. For this reason, the spline engagement portion 4
At 0, each of the female spline teeth and each of the male spline teeth do not contact each other over the entire length in the axial direction, but come into strong contact only in a part of the axial direction. Therefore, the surface pressure of the contact portion is increased, and the fretting wear is more easily generated at the contact portion. As a result, a circumferential gap is easily generated in the spline engagement portion 40 based on the fretting wear, and the spline engagement portion 4
Since the time until the rattling in the circumferential direction of 0 becomes large, it is difficult to sufficiently secure the durability of the spline engaging portion 40. The wheel drive bearing unit of the present invention has been invented in order to prevent the above fretting wear due to the above-described causes.

[0015]

A bearing unit for driving a wheel according to the present invention comprises an outer ring, a hub, a rolling element, a drive shaft member, and the like, as in the second example of the conventional structure shown in FIG. , A retaining ring. Of these, the outer ring has a first flange on the outer peripheral surface for coupling and fixing to the suspension device, and a double-row outer ring raceway on the inner peripheral surface, and does not rotate during use. or,
The hub has a second flange for supporting the wheel at a portion near the outer end of the outer peripheral surface, a first inner ring track directly at the intermediate portion or via a separate inner ring, and a spline hole at the center. And an inner ring having a second inner raceway formed on the outer peripheral surface thereof at a portion near the inner end of the outer peripheral surface. A plurality of rolling elements are provided between each of the outer raceways and each of the first and second inner raceways so as to freely roll. In the drive shaft member, a spline shaft that engages with the spline hole is provided at an outer end, and an inner end is an outer race for a constant velocity joint that forms a constant velocity joint. Further, the retaining ring has an inner engaging portion provided on an outer peripheral surface of an outer end portion of the spline shaft, and an outer engaging portion provided on a portion of the inner peripheral surface of the hub facing the inner engaging portion. To prevent the spline shaft from slipping out of the spline hole.

In particular, in the wheel drive bearing unit according to the present invention, a cylindrical male surface fitting portion hardened and hardened in a state where fine irregularities are formed on the outer peripheral surface of the intermediate portion of the drive shaft member. Are formed at the inner ends of the hubs, respectively. Then, the male-side fitting portion and the female-side fitting portion are press-fitted in a state where the irregularities provided on the male-side fitting portion bite into the female-side fitting portion.

[0017]

According to the wheel drive bearing unit of the present invention configured as described above, the assembling work can be facilitated, and the male spline portion provided on the outer peripheral surface of the spline shaft and the inner peripheral surface of the spline hole can be provided. The occurrence of rattling noise at the spline engagement portion between the female spline portion and the female spline portion can be prevented. That is, according to the present invention, since the connection between the hub and the spline shaft is performed by the retaining ring, the assembling work can be facilitated. Further, the male fitting portion and the female fitting portion are press-fitted in a state in which the irregularities provided on the male fitting portion side are cut into the female fitting portion at a portion separated from the spline engaging portion. Since the hub and the spline shaft are aligned with each other, the hub and the spline shaft are not relatively displaced vigorously in the rotation direction. For this reason, the side surface of each male spline tooth forming the male spline portion does not vigorously collide with the side surface of each female spline tooth forming the female spline portion, and the occurrence of the rattling noise can be prevented. .

[0018]

FIG. 1 shows a first embodiment of the present invention. The feature of the present invention is to facilitate the work of connecting the wheel supporting bearing unit 1b and the constant velocity joint 2b, and to realize the spline shaft 17 and the spline hole 1
4 in that the structure of the connecting portion between the hub 4a and the drive shaft member 18b is devised in order to prevent generation of rattling noise in the spline engaging portion 40 between the hub 4a and the driving shaft member 18b. The configuration and operation of the other parts are almost the same as those of the second example of the conventional structure shown in FIG. 4 described above. Hereinafter, a description will be given mainly of a characteristic portion of the present invention and a portion different from the second example of the conventional structure.

In the case of this embodiment, the spline shaft 17 and the outer race 1 for the constant velocity joint are provided at an intermediate portion of the drive shaft member 18b made of a hardenable iron-based metal such as carbon steel.
5, a male fitting portion 41 is formed. The male fitting portion 41 has a diameter slightly larger than that of the spline shaft 17, and fine irregularities are formed on the outer peripheral surface by knurling. The shape of the fine irregularities is not particularly limited, but preferably, the grooves and the ridges, each of which is long in the axial direction (the left-right direction in FIG. 1), are alternately arranged in the circumferential direction as if the serrations were fine. Use those formed at equal intervals. In any case, the male fitting portion 4
After forming the fine irregularities by knurling, the outer peripheral surface of 1 is quenched and cured.

On the other hand, at the inner end (the right end in FIG. 1) of the hub 4a also made of an iron-based metal such as carbon steel, a cylindrical-side female fitting portion 42 is formed. . The inner diameter of the female fitting portion 42 is larger than the spline hole 14 formed in the hub 4a. Therefore, the thickness of the portion where the female engaging portion 42 is formed on the inner peripheral surface is smaller than the thickness of the other portions. In addition, the female side fitting portion 42
Is slightly smaller than the outer diameter (diameter of the circumscribed circle of fine irregularities) of the male fitting portion 41 in the free state.

The drive shaft member 18b having the male-side fitting portion 41 as described above and the hub 4a having the female-side fitting portion 42 as described above connect the spline shaft 17 to the spline hole 14. At the same time, the male fitting portion 41 is combined with the female fitting portion 42 by press-fitting. In this state, the tops of a number of ridges forming fine irregularities formed on the outer peripheral surface of the male fitting portion 41 are fixed to the female fitting portion 4.
2 bites into the inner surface. With this biting, the relative displacement of the drive shaft member 18b and the hub 4a in the rotation direction is suppressed. For this reason, the spline shaft 17
The spline engaging portion 4 is formed by engaging the male spline portion 38 of FIG.
0, even if there is some backlash, it is possible to prevent the side surfaces of the teeth constituting both spline portions 38 and 39 from violently colliding with each other, so that the above-mentioned rattling noise is generated when the automobile is running. Can be prevented. Note that the two spline portions 3
If there is a small gap between the side surfaces of the teeth constituting the gears 8 and 39, the drive shaft member 18b and the hub 4a are rotated relative to each other by a small angle in the rotation direction until the gap is lost. Displace. In the case of such a relative displacement, the inner end of the hub 4a provided with the female-side fitting portion 42 is elastically deformed by a small amount in the torsional direction, thereby compensating for the relative displacement of the minute angle. I do. Since the inner end portion has a small thickness and is easily elastically deformed, the relative displacement is smoothly compensated.

As described above, since the occurrence of the rattling noise is prevented by press fitting of the male fitting portion 41 and the female fitting portion 42, the male spline portion 38 None of the female spline portions 39 has a twist angle.
It is a straight spline. Accordingly, the spline teeth constituting the male spline section 38 and the female spline section 39 extend over substantially the entire length in the axial direction.
Abut evenly. For this reason, the contact area increases, the contact pressure decreases, and the contact portion is less likely to be worn. As the contact portion is hardly worn, the male spline portion 38 and the female spline portion 39 are not subjected to a heat treatment for hardening such as quenching. I have left. An O-ring 45 is sandwiched between the inner end surface of the hub 4a and the outer end surface of the outer race 15 for a constant velocity joint, and foreign matter such as muddy water is applied to the spline engagement portion between the spline portions 38 and 39. Is kept out.

Next, FIG. 2 shows a second embodiment of the present invention.
An example is shown. In the case of this example, the outer peripheral surface of the outer ring 3a is simply cylindrical, and the outer ring 3a is attached to a suspension device.
Are fitted and fixed in mounting holes provided in the knuckle 8 (see FIGS. 1 and 4). In order to provide double rows of first and second inner raceways 11a, 13a on the outer peripheral surface of the hub 4b, the first and second inner raceways 11a, A pair of inner races 5 a and 5 b provided with 13 a are fitted to the outside and fixed by caulking portions 43.

The end surface of the caulking portion 43 is in contact with or close to the outer end surface of the outer race 15 for the constant velocity joint, which constitutes the drive shaft member 18c. Then, an O-ring 45 held in a holding groove 44 formed on the outer end face of the constant velocity joint outer ring 15 is elastically brought into contact with the end face of the caulking section 43 so that the caulking section 43 and the constant velocity joint The space between the outer ring 15 and the outer ring 15 is sealed. In the case of this example, the outer engaging portion provided on the inner peripheral surface of the hub 4b is a step 46 formed at the outer edge of the spline hole 14. When assembling the wheel drive axle unit, this step 4
6 includes locking grooves 3 formed on the outer peripheral surface of the spline shaft 17.
2 engages with the retaining ring 33, and the spline shaft 1
7 is prevented from falling out of the spline hole 14.

In the case of the present embodiment in which the hub 4b and the drive shaft member 18C are connected to each other by the above-described structure, the drive shaft made of a hardenable and hardenable iron-based metal such as carbon steel is also used. In the middle part of the member 18c, the spline shaft 1
A male-side fitting portion 41a is formed in a portion between the outer ring 15 and the constant velocity joint outer ring 15. And this male side fitting part 41
On the outer peripheral surface of a, fine irregularities such as a fine pitch of male serrations are formed based on knurling, and the outer peripheral surface portion on which the irregularities are formed is quenched and hardened.

On the other hand, a female-side fitting portion 42a is formed on the inner peripheral surface of the inner end of the hub 4b corresponding to the base end of the caulking portion 43. The inner peripheral surface of the female fitting portion 42a is a cylindrical surface, and has an inner diameter larger than the inner diameter of the spline hole 14 formed at the center of the hub 4b. or,
The inner diameter of the female fitting portion 42a in the free state is slightly smaller than the outer diameter of the male fitting portion 41a in the free state.
In addition, the inner peripheral surface of the female-side fitting portion 42a is not hardened particularly by quenching or the like, and is kept raw and soft.

The drive shaft member 18c having the male-side fitting portion 41a as described above and the hub 4b having the female-side fitting portion 42a as described above connect the spline shaft 17 to the spline hole 14. The male fitting portion 41
a into the female fitting portion 42a. In this state, the tops of a number of ridges forming fine irregularities formed on the outer peripheral surface of the male-side fitting portion 41a bite into the inner peripheral surface of the female-side fitting portion 42a. With this biting, the relative displacement of the drive shaft member 18c and the hub 4b in the rotation direction is suppressed. Therefore, even if there is some backlash in the spline engagement portion 40 formed by engaging the male spline portion 38 of the spline shaft 17 with the female spline portion 39 of the spline hole 14, both spline shafts 17 and 38 are engaged. It is possible to prevent the side surfaces of the teeth constituting the spline portions 38 and 39 from violently colliding with each other, thereby preventing the above-mentioned rattling noise from being generated when the vehicle is running.

In the case of this embodiment, the female spline section 39 of the male spline section 38 and the female spline section 39 is a straight spline having no twist angle. On the other hand, the male spline section 38 has a slightly inclined spline tooth (for example, about 8 minutes) as compared with the conventional structure, and has slightly inclined spline teeth, and its outer peripheral surface is hardened by quenching. Therefore, the male spline section 3
Although the spline teeth forming the female spline portion 8 and the female spline portion 39 are fitted with almost no play, slight play may occur depending on a manufacturing error or the like. Even in such a case, the male side fitting part 41a and the female side fitting part 42a
The generation of rattling noise is prevented based on the fitting with the gear. Further, since the inclination angle of the spline teeth forming the male spline portion 38 is small, the contact area between the spline teeth forming the male spline portion 38 and the spline teeth forming the female spline portion 39 is the same as the conventional area described above. As compared with the case of the structure, the contact area is reduced, the contact pressure is reduced, and the contact portion is less likely to be worn.

In this embodiment, a cap 47 is provided at an intermediate portion of the main body of the hub 4b, and the spline shaft 17
Is fitted and fixed in a state of being closely opposed to the end face of the end portion, thereby closing this intermediate portion. The volume of the space in which the spline shaft 17 and the spline hole 14 are located between the cap 47 and the O-ring 45 is reduced, so that the amount of grease sealed in this space can be reduced. Note that this grease is sealed in order to suppress abrasion even when the male spline portion 38 and the female spline portion 39 rub against each other.

[0030]

The present invention is constructed and operated as described above, so that the assembling operation can be facilitated, the cost can be reduced, and the generation of rattling noise that is unpleasant for the occupant can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view showing the second example.

FIG. 3 is a sectional view showing a first example of a conventional structure.

FIG. 4 is a sectional view showing the second example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a, 1b Wheel support bearing unit 2, 2a, 2b Constant velocity joint 3, 3a Outer ring 4, 4a, 4b Hub 5, 5a, 5b Inner ring 6 Rolling element 7 First flange 8 Knuckle 9 Outer ring track 10 Second Flange 11, 11a First inner raceway 12 Small diameter step 13, 13a Second inner raceway 14 Spline hole 15 Outer race for constant velocity joint 16 Inner race for constant velocity joint 17 Spline shaft 18, 18a, 18b, 18c Drive shaft member DESCRIPTION OF SYMBOLS 19 Outer engaging groove 20 Second spline hole 21 Inner engaging groove 22 Ball 23 Cage 24 Male screw part 25 Nut 26 Drive shaft 27 Male spline part 28 Lock groove 29 Retaining ring 30 Lock step 31 Lock part 32 Locking groove 33 Retaining ring 34 Elastic ring 35 Locking step 36 Locking groove 37 Retaining ring 38 Male spline part 39 Female sprat Down portion 40 splined engagement portion 41,41a male engaging portion 42,42a female engaging portion 43 caulking portion 44 holding groove 45 O-ring 46 step portion 47 cap

Claims (1)

[Claims] An outer ring which has a first flange for coupling and fixing to a suspension device on an outer peripheral surface, a plurality of rows of outer ring raceways on an inner peripheral surface, and which does not rotate during use, and an outer end of the outer peripheral surface. The second flange for supporting the wheel in the deviated part, the first inner ring track also in the middle part directly or via a separate inner ring,
A hub in which a spline hole is provided in the center portion, and an inner ring having a second inner raceway formed on its outer peripheral surface is externally fixed to a portion near the inner end of the outer peripheral surface, the outer raceways, the first and second raceways, A plurality of rolling elements provided between the two inner raceways so as to freely roll, and a spline shaft that is spline-engaged with the spline hole is provided at an outer end portion,
A drive shaft member whose inner end is an outer race for a constant velocity joint that forms a constant velocity joint, an inner engaging portion provided on an outer peripheral surface of an outer end of the spline shaft, and an inner engaging surface formed by an inner peripheral surface of the hub; A wheel drive bearing unit comprising: a retaining ring that extends between an outer engaging portion provided at a portion facing the joint portion and that prevents the spline shaft from falling out of the spline hole. The cylindrical outer male fitting portion quenched and hardened in a state where fine irregularities are formed on the outer peripheral surface of the intermediate portion of the drive shaft member, and the cylindrical female female fitting portion on the inner end of the hub. The male fitting portion and the female fitting portion were press-fitted in such a manner that the irregularities provided on the male fitting portion side were cut into the female fitting portion. A wheel drive bearing unit characterized in that: