JP3533883B2 - Hub unit for wheel support - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The wheel supporting hub unit according to the present invention rotates drive wheels (front wheels of FF vehicle, rear wheels of FR vehicle and RR vehicle, all wheels of 4WD vehicle) of a vehicle with respect to a suspension device. Used to support freely.

[0002]

2. Description of the Related Art A vehicle wheel is supported on a suspension system by a wheel supporting hub unit. FIG. 4 shows US Pat.
Is described in 90732 Pat, shows an example of a wheel support hub unit for supporting (rear wheels of an FF vehicle, the front wheels of the FR vehicle and RR vehicle) driven wheel of a motor vehicle against the suspension system There is. The wheel supporting hub unit 1 includes a hub 2
A pair of inner rings 3a and 3b, an outer ring 4, and a plurality of rolling elements 5 and 5. Of these, the outer end of the outer peripheral surface of the shaft member 2 (outside means the side that is outward in the width direction when assembled in an automobile, and is the left side in each of the drawings including FIG. 4. Conversely, the center in the width direction. The side closer to the inside is referred to as the inside, which is the right side in each figure.) Is formed with a flange 6 for supporting the wheel. A step portion 7 is formed at the base end portion of the flange 6 near the center of the shaft member 2.

The pair of inner rings 3a, 3b are fitted over the intermediate portion and the inner end portion of the shaft member 2, and the outer end surface of the outer inner ring 3a is the stepped surface of the stepped portion 7. The outer end surface of the inner inner ring 3b is abutted against the inner end surface of the outer inner ring 3a. A cylindrical portion 8 is provided at the inner end of the shaft member 2.
And the inner half 3b of the inner side is formed by the first half of the cylindrical portion 8.
The caulking portion 9 is formed by caulking and spreading the portion projecting inwardly from the inner end surface of the disc in the diametrically outward direction. The pair of inner rings 3a and 3b are held between the caulked portion 9 and the step surface of the stepped portion 7.

A pair of (first and second) outer ring raceways 10 and 10 provided on the inner peripheral surface of the outer ring 4 and the inner rings 3 are also provided.
Inner ring raceways 1 (first and second) provided on outer peripheral surfaces of a and 3b
A plurality of rolling elements 5 and 5 are provided between the rolling elements 1 and 11. In the illustrated example, balls are used as the rolling elements 5 and 5, but in the case of a wheel supporting hub unit for a heavy vehicle, tapered rollers may be used as these rolling elements. In addition, the (first) inner ring raceway near the flange 6 may be directly formed on the outer peripheral surface of the shaft member 2 and the outer inner ring 3a may be omitted. In this case, the stepped portion 7 is formed at a position corresponding to the inner side of the outer inner ring 3a shown in FIG. To assemble the wheel supporting hub unit 1 as described above to an automobile, an outward flange-shaped mounting portion 12 formed on the outer peripheral surface of the outer ring 4 is used.
The outer ring 4 is fixed to the suspension device, and the wheel is fixed to the flange 6. As a result, this wheel can be rotatably supported by the suspension device.

On the other hand, FIG. 5 shows a wheel support for supporting a drive wheel of an automobile with respect to a suspension device by using a structure in which a caulking portion for restraining an inner ring is formed on a hub as described above. It is applied to the hub unit for. This Figure 5
In the case of the wheel supporting hub unit 1a for driving wheels shown in FIG. 1, the hub 13 is formed in a cylindrical shape and
A female spline portion 14 is formed on the inner peripheral surface of the No. 3. A drive shaft 16 having a constant velocity joint 15, which will be described later, and a drive member, and a male spline portion formed on the outer peripheral surface is inserted into the female spline portion 14. Then, the inner end surface of the nut 17 screwed onto the tip end portion of the drive shaft 16 is the outer end surface of the hub 13, and the stepped surface 19 of the step portion 18 formed at the base end portion of the drive shaft 16 is the hub 13. The hub 13 and the drive shaft 16 are coupled by tightening the nut 17 in a state of abutting against the inner end surface of the caulked portion 9 formed at the inner end portion. In other words, above
A nut 17 in which the hub 13 is screwed onto the tip of the drive member.
And the nut 17 in a state of being sandwiched between the nut 17 and the driving member.
By tightening the, the hub 13 is connected to the drive member.
It is if fixed.

In the case of the wheel supporting hub unit 1a for the drive wheels shown in FIG. 5, unlike the case of the wheel supporting hub unit 1 for the driven wheels shown in FIG. Of the inner ring 3a is omitted and the pair of inner ring raceways 11, 1
The inner ring raceway 11 on the outer side of 1 is directly formed on the outer peripheral surface of the hub 13. Therefore, the step portion 7 is formed on the inner end portion of the hub 13. When the drive shaft 16 is inserted into the hub 13 so as to connect the hub 13 and the drive shaft 16, the inner peripheral surface of the inner end portion of the hub 13 and the outer peripheral surface of the inner end portion of the drive shaft are connected to each other. In order to prevent them from interfering with each other, a gap is formed between these two peripheral surfaces over the entire circumference.
The wheel support hub unit 1a for driving wheels as described above is
Similar to the wheel support hub unit 1 for the driven wheels described above,
It is fixed to the suspension device by a mounting portion 12 provided on the outer ring 4.
When the vehicle is running, the drive shaft 16 is rotationally driven through the constant velocity joint 15, and the rotational drive force rotates the wheels fixed to the flange 6 of the hub 13.

[0007]

However, in the case of the wheel supporting hub unit 1a for driving wheels shown in FIG. 5, as described above, the hub 13 and the driving shaft 16 are screwed together with the nut 17.
When they are joined together by tightening, the inner end surface of the caulking portion 9 and the step surface 19 of the step portion 18 formed at the base end portion of the drive shaft 16 make line contact over the entire circumference. That is, as shown in detail in FIG.
The shape of the inner end surface of the crimped portion 9 is a convex curved surface as the inner end portion of the cylindrical portion 8 formed on the inner end portion of the hub 13 is bent outward in the diametrical direction in order to form the crimped portion 9. It has become. Therefore, when the nut 17 is screwed and tightened as described above, the top 20 of the convex curved surface formed on the inner end surface of the caulking portion 9 and the step surface 19 abut over the entire circumference, and the caulking is performed. The inner end surface of the portion 9 and the step surface 19 make line contact.

Thus, the inner end surface of the caulking portion 9 and the step surface 19
When the and are in line contact with each other, the surface pressure applied to the inner end surface of the caulked portion 9 becomes very large based on the tightening force of the nut 17. Since the caulking portion 9 is not subjected to hardening treatment such as quenching because it is necessary to form the caulking portion 9,
When a large surface pressure is applied as described above, the caulked portion 9 is easily plastically deformed. When the caulked portion 9 is plastically deformed in this way, the nut 17 screwed and tightened on the tip portion of the drive shaft 16 may loosen. In order to prevent the plastic deformation of the caulking portion 9 due to the above-mentioned causes, an annular groove into which the caulking portion 9 can freely enter is formed in the step surface 19 of the drive shaft 16, and the step surface 19 and the inner ring are formed. it is considered also to directly contact the inner end surface of the 3b, in this case, due to that the shape of the stepped portion 18 of the constant velocity joint 15 is complicated, because the increase in manufacturing cost of the constant velocity joint 15 , Not preferable. In view of such a situation, the wheel supporting hub unit of the present invention is invented to prevent the deformation of the caulked portion without complicating the shape of the constant velocity joint 15.

[0009]

A wheel supporting hub unit according to claim 1 of the wheel supporting hub unit of the present invention.
Like the conventional wheel supporting hub unit shown in FIG. 5, the knit is provided on the hub that is rotationally driven by the drive member during use and on the outer peripheral surface of the outer end portion of the hub. A flange for supporting and fixing the first inner ring raceway formed on the outer peripheral surface of the intermediate portion of the hub directly or through an inner ring separate from the hub, and an inner end portion of the hub. A step portion having an outer diameter smaller than that of the portion forming the first inner ring raceway, an inner ring having a second inner ring raceway formed on the outer peripheral surface and fitted onto the step portion, and an inner peripheral surface To have a first outer ring raceway facing the first inner ring raceway and a second outer ring raceway facing the second inner ring raceway, an outer ring that does not rotate during use, and to attach this outer ring to a suspension device, The mounting portion provided on the outer peripheral surface of the outer ring and the first and second inner ring raceways Between the first and second outer ring raceways, and a rolling element disposed by plurality, respectively.
The inner ring externally fitted to the stepped portion is formed by caulking and diametrically expanding a portion of the inner end portion of the hub projecting inwardly more than the inner ring externally fitted to the stepped portion. The hub is connected and fixed to the hub in a state in which the caulked portion is pressed against the stepped surface of the stepped portion. Further, the nut is tightened in a state of being clamped by a nut screwed with the hub of the drive member and the drive member , whereby the hub is coupled and fixed to the drive member .

Particularly, in the wheel supporting hub unit according to claim 1 of the present invention, the nut and the drive portion are provided.
A flat surface is provided on the inner end surface of the crimped portion, which is a portion sandwiched by the material, so as to be in surface contact with the drive member . More preferably, at least a part of this flat surface (outer peripheral portion) is positioned diametrically outward from the inner peripheral surface of the inner ring fitted on the stepped portion of the hub. Also, as described in claim 5.
The wheel supporting hub unit shown in FIG.
Like the conventional wheel support hub unit,
The hub that is driven to rotate by the
It is provided on the outer peripheral surface of the part to support and fix the wheel to this hub
Directly on the flange of the hub and the outer peripheral surface of the intermediate part of the hub.
Inner ring raceway formed through an inner ring separate from the hub of
And the first inner ring gauge formed at the inner end of the hub.
A step with a smaller outer diameter than the part where the road is formed
And a second inner ring raceway is formed on the outer peripheral surface and is externally fitted to the stepped portion.
The inner ring that has been formed and the inner peripheral surface faces the first inner ring raceway.
The second outer ring raceway and the second inner ring raceway facing each other
The outer ring that has an outer ring track that does not rotate during use and
The outer ring of this outer ring is installed to attach the ring to the suspension system.
Stripped mounting portion, the first and second inner ring raceways, and the first
Provide a plurality of each between the first and second outer ring raceways
And a rolling element that has been rolled. And it was fitted on the above step
The inner ring is the inner ring that is fitted onto this step at the inner end of the hub.
The cylindrical part formed on the part that protrudes inward
The step of the above step is formed by the caulking part formed by swaging to one side.
Connected and fixed to the above hub while holding it toward the difference surface.
It In addition, this hub has an outer end surface on the tip of the drive member.
Place the inner end surface of the caulked part above the inner end surface of the screwed nut.
The stepped surface of the step formed at the inner end of the drive member
The nut is tightened with
It is fixedly connected to the driving member. In particular, claim 5
In the wheel supporting hub unit, the drive member is
Is a portion that contacts the step surface of the step formed on the inner end of the
The inner end surface of the caulked portion is formed on the inner end portion of the drive member.
A flat surface is provided so that it can come into surface contact with the stepped surface of the formed step.
It More preferably, at least a part of this flat surface (outer
The inner peripheral surface of the inner ring that is fitted around the stepped portion of the hub.
Located diametrically outward than.

[0011]

The wheel supporting hub unit of the present invention having the above-described structure has the function of rotatably supporting the wheel with respect to the suspension system. The operation itself is the same as the conventional wheel supporting hub shown in FIGS. Similar to the unit. Particularly, according to the wheel supporting hub unit of the present invention, in the case where the hub and the driving member that constitute the wheel supporting hub unit are coupled by screwing and tightening the nut provided at the tip of the driving member. Then, the inner end surface of the caulked portion and the driving member are in surface contact with each other. Therefore, the surface pressure applied to the inner end surface of the caulked portion based on the tightening force of the nut can be reduced.

Further, at least a part of the flat surface (outer peripheral portion) formed on the inner end surface of the caulked portion is positioned diametrically outward from the inner peripheral surface of the inner ring fitted onto the step portion of the hub. In this case, the axial load applied to the caulked portion based on the tightening of the nut causes the portion where the flat surface is formed in the outer peripheral portion of the caulked portion to be formed between the inner end surface of the inner ring and the drive member . It is clamped in the axial direction. In this state, only the compressive load is applied to the outer peripheral portion of the crimped portion, so that the axial load can be effectively supported. Therefore, even if a large axial load is applied to the inner end surface of the caulked portion based on the tightening of the nut, the caulked portion is hardly plastically deformed. In addition, as described above, a part of the flat surface formed on the inner end surface of the caulked portion is not positioned diametrically outward from the inner peripheral surface of the inner ring fitted on the step portion of the hub, When the whole is positioned inward of the inner peripheral surface of the inner ring in the diametrical direction, bending stress is generated at the inner end portion of the hub due to the tightening of the nut. Then, the caulking portion formed on the inner end portion of the hub may be plastically deformed based on the bending stress. Therefore, when carrying out the present invention, it is preferable that at least a part of the flat surface has a diameter larger than that of the inner peripheral surface of the inner ring (if the inner end opening of the inner ring has a chamfer, this chamfer). The hub is located outward in the direction to prevent bending stress from being generated at the inner end of the hub, and only the compressive stress in the axial direction is applied to the inner end. If such a preferable structure is adopted, the inner ring restraining strength by the caulking portion is lowered,
Alternatively, the nut screwed and tightened on the tip of the driving member does not loosen. Therefore, it is possible to provide a highly reliable wheel supporting hub unit.

[0013]

1 and 2 show a first example of an embodiment of the present invention. The feature of the present invention is that the hub 13
The caulking portion 9a for holding the inner ring 3b against a is
The nut 1 screwed into the male screw portion at the tip of the hub 13a
The point is that the shape of the caulked portion 9a is devised so as not to be plastically deformed due to the axial load due to the tightening of No. 7. The structure and operation of the other parts are the same as those of the conventional structure shown in FIG. 5 described above, and therefore redundant description will be omitted or simplified, and the characteristic part of the present invention will be mainly described below.

In order to fix the inner ring 3b to the inner end portion of the hub 13a, the inner end surface of the caulked portion 9a formed on the inner end portion of the hub 13a is subjected to coining or turning to make it A circular ring-shaped flat surface 21 perpendicular to the central axis of the hub 13a is formed. Such a circular ring-shaped flat surface 21 is diametrically outward from the inner peripheral surface of the inner ring 3b in which at least a part (the outer peripheral portion) of the flat surface 21 is fitted onto the step portion 7 of the hub 13a. It is formed in a state of being located at. More preferably, the flat surface 21
And a flat surface 23 formed on the inner end surface of the inner ring 3b,
Overlap each other in the axial direction. Both flat surfaces 2
1, 23 are parallel to each other. And the hub 13
When a and the drive shaft 16 that constitutes a drive member together with the constant velocity joint 15 are coupled, the base end portion of the drive shaft 16 is attached to the annular flat surface 21 which is the inner end surface of the caulking portion 9a. In other words, the step surface 19 of the step portion 18 formed on the shoulder portion of the constant velocity joint 15 is abutted. And
In this state, by tightening the nut 17 screwed onto the male screw portion at the tip of the drive shaft 16, the nut 17 is tightened.
The hub 13 a is sandwiched between the step portion 18 and the step portion 18.

With the wheel supporting hub unit of the present embodiment configured as described above, the action itself of rotatably supporting the wheel with respect to the suspension device is the same as that of the conventional wheel supporting hub unit shown in FIG. The same as 1a. Particularly, in the case of the wheel supporting hub unit of this example, when the hub 13a and the drive shaft 16 are coupled to each other as described above, the step portion formed on the inner end surface of the caulking portion 9a and the base end portion of the drive shaft 16 is described. The stepped surface 19 of 18 makes surface contact over the entire circumference. Therefore, the nut 1
Based on the tightening force of 7, the surface pressure applied to the inner end surface of the caulked portion 9a can be reduced. Further, the axial load applied to the caulked portion 9a based on the tightening of the nut 17 is applied to a portion of the circular ring-shaped flat surface 21 located radially outward of the inner peripheral surface of the inner ring 3b. By sandwiching it between the flat surface 23 formed on the inner end surface of the inner ring 3b that has been hardened by quenching and the stepped surface 19, the bearing can be effectively supported. Therefore, the caulking portion 9a
In addition, even when a large axial load is applied due to the tightening of the nut 17, the caulked portion 9a is hardly plastically deformed. Therefore, the inner ring 3b formed by the caulking portion 9a
There is no decrease in the restraining strength and the nut 17 screwed and tightened on the tip of the hub 13a does not loosen. As a result, it is possible to provide a highly reliable wheel supporting hub unit.

Of the circular ring-shaped flat surface 21, the portion located radially outward of the inner peripheral surface of the inner ring 3b (the outer peripheral portion of the circular ring-shaped flat surface 21) is the nut 17 described above. It is preferable to make it as large as possible in order to more effectively support the axial load applied to the caulked portion 9a on the basis of the tightening. For this reason, in the case of this example, most of the circular ring-shaped flat surface 21 except for a part near the inner circumference is located radially outward of the inner circumference of the inner ring 3b. . Further, also in the case of the wheel supporting hub unit of this example, as in the case of the conventional wheel supporting hub unit 1 shown in FIG. 4, the outer inner ring raceway 11 (first Inner ring raceway) of this hub 13
Instead of being formed directly on the outer peripheral surface of the intermediate portion of a, it may be formed via a separate inner ring 3a (see FIG. 3).

Next, FIG. 3 shows a second embodiment of the present invention.
An example is shown. In the case of this example, the spacer ring 22 is externally fitted to a portion of the inner end portion of the hub 13a protruding inward from the inner end surface of the inner ring 3b externally fitted to the hub 13a. Then, the cylindrical portion 8 existing inside the spacer ring 22 at the inner end portion of the hub 13a is caulked and expanded outward in the diametrical direction to hold the spacer ring 22 toward the inner end surface of the inner ring 3b. The inner ring 3b is fixedly connected to the hub 13a. In the case of this example, by providing such a spacer ring 22, it is possible to elastically deform the inner ring 3b outward in the diametrical direction even when the caulking strength when caulking and expanding the cylindrical portion 8 is sufficiently increased. To prevent.

That is, in the case of the present example, the diametrically outward force applied when the cylindrical portion 8 is swaged and expanded is received by the spacer ring 22 fitted on the hub 13a. Therefore, it is possible to prevent the diameter of the inner ring 3b from changing with the work of caulking and expanding the cylindrical portion 8. In the case of this example, the caulking portion 9a is tightened based on the tightening of the nut 17 (FIG. 1).
Axial load is applied to the portion of the circular ring-shaped flat surface 21 formed on the inner end surface of the crimped portion 9a, which is located diametrically outward from the inner peripheral surface of the inner ring 3b, and is hardened by quenching or the like. The bearing is effectively supported at a portion between the treated spacer ring 22 and the inner end surface. Spacer 2
The configuration and operation other than the point that 2 is provided are the same as in the case of the first example described above.

[0019]

Since the wheel supporting hub unit of the present invention is constructed and operates as described above, the caulking portion for holding the inner ring against the hub is plastically deformed based on the tightening of the nut. This prevents the nut from loosening. Therefore, it is possible to provide a highly reliable wheel supporting hub unit.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a view similar to FIG. 2, showing a second example of the embodiment of the present invention.

FIG. 4 is a sectional view showing a wheel supporting hub unit for driven wheels as a first example of a conventional structure.

FIG. 5 is a cross-sectional view showing a wheel supporting hub unit for driving wheels, which is a target of the present invention, as a second example of a conventional structure.

FIG. 6 is an enlarged view of part A in FIG.

[Explanation of symbols]

1, 1a Wheel support hub unit 2 hubs 3a, 3b Inner ring 4 outer ring 5 rolling elements 6 flange 7 steps 8 cylindrical part 9, 9a Caulking part 10 Outer ring track 11 Inner ring track 12 Mounting part 13, 13a hub 14 Female spline part 15 constant velocity joint 16 drive shaft 17 nuts 18 steps 19 steps 20 top 21 flat surface 22 Spacer 23 Flat surface

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-106426 (JP, A) JP-A-63-184501 (JP, A) JP-A-5-215757 (JP, A) JP-A-9- 164803 (JP, A) Actual flat 1-82903 (JP, U) Actual flat 6-73459 (JP, U) Japanese Patent Publication Sho 49-19361 (JP, B1) US Patent 5226738 (US, A) US Patent 5490732 (US, A) US Patent 5544962 (US, A) US Patent 5725285 (US, A) European Patent Application Publication 736398 (EP, A 2) (58) Fields searched (Int.Cl. ⁷ , DB name) B60B 27 / 00 B60B 35/00

Claims (8)

(57) [Claims] A hub which is rotationally driven by a drive member when in use, a flange provided on an outer peripheral surface of an outer end portion of the hub , for supporting and fixing a wheel to the hub, and an intermediate portion of the hub. A first inner ring raceway formed directly on the outer peripheral surface of the part or through an inner ring separate from the hub, and a portion formed on the inner end part of the hub, which forms the first inner ring raceway. A stepped portion having a smaller outer diameter dimension, an inner ring formed on the outer peripheral surface with a second inner ring raceway and externally fitted on the stepped portion, and a first inner ring surface facing the first inner ring raceway. To have an outer ring raceway and a second outer ring raceway facing the second inner ring raceway, and an outer ring that does not rotate during use, and to attach this outer ring to a suspension device,
A mounting portion provided on the outer peripheral surface of the outer ring, a plurality of rolling elements provided between the first and second inner ring raceways and the first and second outer ring raceways, respectively, The inner ring externally fitted to the step portion is formed by caulking and diametrically expanding a portion of the inner end of the hub projecting inwardly more than the inner ring externally fitted to the step portion. the nut of which is connected and fixed to said hub in a state attached suppressed toward the stepped surface, a state where the hub is sandwiched between the <br/> driving member of the nut Toko screwed to the distal end of the drive member in the wheel supporting hub unit for coupling secured to the drive member by the tightening of by the said nut and said drive member
On the inner end surface of the crimped portion, which is the sandwiched portion, the above
A wheel support hub unit characterized by having a flat surface that can come into surface contact with a drive member . 2. The method according to claim 1, wherein at least a part of the flat surface provided on the inner end surface of the caulking portion is located diametrically outward of the chamfer existing in the inner end opening on the inner peripheral surface of the inner ring. The wheel support hub unit described. 3. A hardening treatment is not applied to the caulked portion,
The wheel supporting hub unit according to claim 1 or 2. 4. The wheel supporting hub unit according to claim 1, wherein a caulking portion is sandwiched between a drive member and a flat surface formed on the inner end surface of the hardened inner ring. 5. A hub which is rotationally driven by a drive member when in use, a flange provided on an outer peripheral surface of an outer end portion of the hub, for supporting and fixing a wheel to the hub, and an outer peripheral surface of an intermediate portion of the hub. , The first inner ring raceway formed directly or via an inner ring separate from this hub, and the outer diameter dimension formed at the inner end portion of the hub, which is the outer diameter dimension of the portion forming the first inner ring raceway, A reduced step portion, an inner ring that has a second inner ring raceway formed on the outer peripheral surface and is externally fitted to the step portion, a first outer ring raceway that faces the first inner ring raceway on the inner peripheral surface, and the above An outer ring that has a second outer ring raceway facing the second inner ring raceway and does not rotate during use, and to attach this outer ring to the suspension device,
A mounting portion provided on the outer peripheral surface of the outer ring, a plurality of rolling elements provided between the first and second inner ring raceways and the first and second outer ring raceways, respectively, The inner ring externally fitted to the stepped portion is formed by caulking and diametrically expanding a cylindrical portion formed at a portion of the inner end of the hub projecting inwardly more than the inner ring externally fitted to the stepped portion. Is fixed to the hub in a state of being pressed toward the stepped surface of the stepped portion by a portion, and the hub has an outer end surface on the inner end surface of a nut screwed to the tip portion of the drive member, and the hub of the caulked portion. In a wheel supporting hub unit, the inner end surface of which is tightened by tightening the nut in a state of being brought into contact with the step surface of a step formed on the inner end of the drive member. At the portion that contacts the step surface of the step formed at the inner end of the drive member That the inner end face of the crimped portion, the wheel supporting hub unit, characterized in that there is provided a step surface and surface contact freely flat surface of the step portion formed on the inner end of the drive member. 6. The method according to claim 5, wherein at least a part of the flat surface provided on the inner end surface of the caulking portion is positioned radially outward of the chamfer existing in the inner end opening of the inner peripheral surface of the inner ring. The wheel support hub unit described. 7. The caulking portion is not subjected to hardening treatment,
The wheel supporting hub unit according to claim 5 or 6. 8. The wheel supporting hub unit according to claim 5, wherein a caulking portion is sandwiched between a drive member and a flat surface formed on the inner end surface of the hardened inner ring.