JP2001206004A - Bearing unit for wheel drive - Google Patents

Abstract

[PROBLEMS] To effectively secure sufficient durability even when the inner ring 22 is fixedly connected to a hub 3a by a caulking portion 9 provided at an inner end of the hub 3a. A large-diameter cylindrical portion (29) is formed at a part of a spline shaft (14a) constituting a drive shaft member (13a), which is deviated inward in the axial direction from a male spline portion (20). The base half of the cylindrical portion 10 is provided at a portion of the outer peripheral surface of the large-diameter cylindrical portion 29 where a part of the inner peripheral surface is closely opposed. When a bending moment acts on the inner end of the housing part 15, a part of the outer peripheral surface of the large-diameter cylindrical part 29 comes into contact with a part of the inner peripheral surface of the base half of the cylindrical part 10. And the male spline section 20 and the small-diameter cylindrical section 3
A large bending moment is prevented from acting on the step portion 41 between 0 and 0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A wheel drive bearing unit according to the present invention is a so-called fourth-generation hub unit in which a constant velocity joint and a hub unit are integrated, and is supported by an independent suspension type suspension. Drive wheel ｛F
All front wheels of F vehicles (front engine front wheel drive vehicles), rear wheels of FR vehicles (front engine rear wheel drive vehicles) and RR vehicles (rear engine rear wheel drive vehicles), and all 4WD vehicles (four wheel drive vehicles) The wheel is rotatably supported with respect to the suspension device, and is used to rotationally drive the drive wheel.

[0002]

2. Description of the Related Art In order to rotatably support wheels with respect to a suspension device, various axle units in which an outer wheel and an inner wheel are rotatably combined via rolling elements have been used. 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. As a so-called fourth-generation hub unit, a wheel drive bearing unit that can be configured to be relatively small and lightweight in combination with such a constant velocity joint, it has been conventionally disclosed in Japanese Utility Model Application Laid-Open No. 61-944.
No. 03, JP-A-7-317754, U.S. Pat. No. 4,881,842, or U.S. Pat.
No. 11 is known.

[0003] FIG.
11 shows an example of the conventional structure described in the specification of Japanese Patent No. 11. Outer ring 1 that is not fitted to a knuckle 5 that forms a suspension device and that does not rotate during use in a state of being assembled to a vehicle
Are provided with multiple rows of outer raceways 2, 2. A hub 3 is supported inside the outer race 1 concentrically with the outer race 1. This hub 3 is an outer end of an outer peripheral surface (an end which is located outside in the width direction when assembled to an automobile,
Left side of the figure) Mounting flange 4 for supporting the wheel on the near side
Is provided. A first inner race 7a having a first inner raceway 6 formed on the outer periphery of the hub 3 at an intermediate portion of the outer periphery.
To the inner end (the end on the center in the width direction in the assembled state to the automobile, the right end in FIGS. 1 to 3, 5 and 6),
Second inner race 7 having a second inner raceway 8 formed on its outer peripheral surface
b are externally fitted. The inner end surface of the second inner ring 7b is held down by a caulking portion 9 provided at the inner end portion of the hub 3 so that the caulking portion 9 and one side surface of the base end of the mounting flange 4 (FIG. Between the inner rings 7a, 7b, and between the inner rings 7a, 7b.
Are fixedly connected to the hub 3. The caulking section 9
Of the cylindrical portion 10 provided near the inner end of the hub 3,
The portion protruding from the inner end face of the second inner ring 7b is formed by plastically deforming diametrically outward. A plurality of rolling elements 11, 11 are provided between the outer raceways 2, 2 and the first and second inner raceways 7a, 7b, respectively, so as to freely roll. The hub 3 is rotatably supported inside.

[0004] A spline hole 12 is formed in the center of the hub 3. The hub 3 and the drive shaft member 13 are combined to form a wheel drive bearing unit. At the outer end of the drive shaft member 13, there is provided a spline shaft 14 having a male spline portion 20 on the outer peripheral surface thereof for spline engagement with a female spline portion 19 formed on the inner peripheral surface of the spline hole 12. . The inner end portion of the drive shaft member 13 is a housing portion 15 serving as an outer ring of a Zeppa type constant velocity joint. An outer track 16 of the constant velocity joint is formed on an inner peripheral surface of the housing portion 15. The male spline section 2
0 and the housing portion 13 are continuous with each other by a cylindrical portion 40 having a cylindrical outer peripheral surface. Further, the space between the outer peripheral surface of the cylindrical portion 40 and the outer end surface of the housing portion 13 is
The curved surfaces 42 having a sufficiently large radius of curvature have a circular arc-shaped section so that the stress is prevented from being excessively concentrated at a portion between the two surfaces.

[0005] The drive shaft member 13 and the hub 3 are combined in a state where the spline shaft 14 is inserted into the spline hole 12. The spline shaft 14 is prevented from coming out of the spline hole 12 by a connecting member 17 made of an elastic material, which constitutes a retaining mechanism and engages with the two members 13 and 3 unevenly. still,
A part of the coupling member 17 is provided with encoders 18 made of a magnetic material or a permanent magnet.
Rotation speed can be detected.

When assembling the wheel drive bearing unit constructed as described above to a vehicle, the outer ring 1 is fixedly fitted to the knuckle 5 and the drive wheel is fixed to the hub 3 by the mounting flange 4. Further, the outer end of a drive shaft (not shown), which is rotationally driven by the engine via a transmission, is spline-engaged with the inside of a constant velocity joint inner ring (not shown) provided inside the housing portion 15. When the automobile is running, the rotation of the inner ring for the constant velocity joint is transmitted to the spline shaft 14 via a plurality of balls and the housing portion 15, and the drive wheels fixed to the hub 3 by the spline shaft 14 are rotated. Drive rotationally.

In the case of the wheel drive bearing unit constructed and operated as described above, the inner rings 7a and 7b are fixedly connected to the hub 3 by the caulking portion 9 provided at the inner end of the hub 3. Therefore, for example, the number of components can be reduced and the cost can be reduced as compared with the case where the coupling and fixing are performed using a member separate from the hub 3 such as a nut.

[0008]

In the case of the conventional structure as described above, it is difficult to achieve both a reduction in weight and a sufficient durability. The reason will be described below. In the case of the above-described conventional structure, a cylindrical portion 10 is provided near the inner end of the hub 9 in order to form the caulked portion 9 at the inner end of the hub 3. Also, the inner diameter of the cylindrical portion 10 is
The thickness of the cylindrical portion 10 is reduced by making it larger than the diameter of the tooth bottom circle of the female spline portion 19 provided on the inner peripheral surface of the cylindrical portion 2. By reducing the thickness of the cylindrical portion 10 in this way, the force required to form the caulked portion 9 is reduced, and the inner end of the hub 3 is formed when the caulked portion 9 is formed. The applied load is applied to the female spline portion 19, which has a large change in wall thickness in the circumferential direction, to prevent the occurrence of damage such as cracks in this portion. or,
The overall length of the cylindrical portion 10 is sufficiently large so that the load applied when forming the caulking portion 9 can be sufficiently prevented from being applied to the female spline portion 19. Therefore,
If the structure between the inner peripheral surface of the cylindrical portion 10 and the outer peripheral surface of the drive shaft member 13 facing this inner peripheral surface is not particularly considered, as shown in FIG. A relatively large space 21 is formed over the entire circumference between the inner peripheral surface of the portion 10 and the outer peripheral surface of the cylindrical portion 40 provided at an intermediate portion of the drive shaft member 13.

On the other hand, during operation of the wheel drive bearing unit, the center axes of the housing part 15 serving as the outer ring of the Zeppa type constant velocity joint and the center axis of the inner ring for the constant velocity joint also serving as the inner ring are inconsistent ( If the driving force (torque) is transmitted through this constant velocity joint in a state where the axis intersection angle is not 180 degrees, the radial load generated in the constant velocity joint becomes uneven in the circumferential direction. Thus, a bending moment acts on the drive shaft member 13. Even in the case where the bending moment acts as described above, in the case of the above-described conventional structure, the cylindrical portion 10
Since a relatively large space 21 exists between the inner peripheral surface of the drive shaft member 13 and the outer peripheral surface of the drive shaft member 13, a portion of the drive shaft member 13 other than the male spline portion 20 is connected to the hub 3.
Does not come into contact with the inner peripheral surface.

For this reason, the bending acting on the drive shaft member 13 is performed.
The distribution of the bending moment is as shown in FIG. For example,
As shown by an arrow in FIG.
Bending moment M₀ Assuming that
In the case of the conventional structure described above, the male spline section 20 is
At both end positions of the spline engaging portion with the spline portion 19,
At point A and point B, the outer peripheral surface of the drive shaft member 13 rises.
It contacts the inner peripheral surface of the hub 3 (FIG. 5). And these
The points A and B have the size of F_A And F _B Is
The forces act in opposite directions. For this reason, the drive shaft
The member 13 has a cross section including the inner end of the drive shaft member 13.
From the point, which is the inner end position of the spline engagement part
The male spline section 20 and the cross section including
A point C on the step portion 41 at a portion between the cylindrical portion 40 and the outer peripheral surface.
And the bending moment acting on the drive shaft member 13
Maximum value M₀ Work equally well.

On the other hand, as the rotation of the drive shaft member 13 is transmitted to the hub 3, a torque acts on the drive shaft member 13, and this torque causes a large cross section of the drive shaft member 13. Stress occurs. This drive shaft member 13
Among them, since the entire torque to be transmitted by the drive shaft member 13 is applied to the cylindrical portion 40 deviated from the male spline portion 20, the stress generated in the cross section also increases. Accordingly, in the drive shaft member 13, the point C on the step portion 41 where the stress tends to be concentrated in shape is the portion where the strength is most likely to be insufficient. Therefore, if the bending moment acting on this point C can be kept small, the durability of the entire wheel drive bearing unit can be ensured. On the other hand, by increasing the diameter of the spline shaft 14 constituting the drive shaft member 13, it is conceivable to increase the strength of the cross-sectional portion including the point C. In this case, however, the wheel drive bearing unit is used. It is not preferable because it causes an increase in size and an increase in weight. In the conventional structure shown in FIG.
However, although the above-mentioned stress is somewhat relieved, the effect is limited because the connecting member 17 is an elastic material. In addition, the drive member 13 and the hub 3 are connected by the connecting member 17.
5 itself is not sufficient, and the conventional structure shown in FIG. 5 is not practical. In view of the above-described circumstances, the wheel drive bearing unit of the present invention ensures sufficient durability even when the inner ring is fixedly connected to the hub by the caulking portion provided at the inner end of the hub. It was invented to be effective.

[0012]

A bearing unit for driving a wheel according to the present invention has an outer ring, a hub, a plurality of rolling elements, and a drive shaft member, as in the case of the conventional structure shown in FIG. And a retaining mechanism. Of these, the outer ring has a double-row outer ring track on the inner peripheral surface, and does not rotate during use.
Further, the hub has a mounting flange for supporting the wheel at a portion near the outer end of the outer peripheral surface, a first inner ring raceway directly at the intermediate portion or via a separate inner ring, and a spline hole at the center portion. , Respectively. At the same time, the hub has 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. The rolling elements are provided so as to freely roll between the outer raceways and the first and second inner raceways. In the drive shaft member, a spline shaft that engages with the spline hole is provided at an outer end portion, and an inner end portion is a housing portion serving as an outer ring of a constant velocity joint. Further, the retaining mechanism is provided between the drive shaft member and the hub to prevent the spline shaft from falling out of the spline hole. Then, at the inner end portion of the hub, a portion protruding from the inner end surface of the inner ring externally fitted to a portion near the inner end of the outer peripheral surface of the hub is plastically deformed radially outward by a caulking portion formed by a caulking portion of the inner ring. The inner ring is fixed to the hub by holding down the inner end face.

[0013] In particular, in the wheel drive bearing unit of the present invention, a part of the drive shaft member, which deviates inward in the axial direction from a male spline portion provided on the outer peripheral surface of the spline shaft. And a cylindrical portion provided at the inner end of the hub such that at least a part of the inner peripheral surface thereof faces the outer peripheral surface of the cylindrical portion. With the use of the above-described wheel drive bearing unit, the constant-velocity joint is displaced in a state in which the center axes of the housing part serving as the outer ring of the constant-velocity joint and the inner ring for the constant-velocity joint also serving as the inner ring are not coincident. When a torque of a predetermined magnitude or more is applied to the housing from the joint inner ring, a part of the outer peripheral surface of the columnar part comes into contact with a part of the inner peripheral surface of the cylindrical part.

[0014]

According to the wheel drive bearing unit of the present invention having the above-mentioned structure, even when the inner ring is fixedly connected to the hub by the caulking portion provided at the inner end of the hub,
During use, the bending moment acting on the portion of the drive shaft member where the strength is most likely to be insufficient can be reduced, and sufficient durability can be effectively ensured.

[0015]

FIG. 1 shows a first embodiment of the present invention. It should be noted that the feature of the present invention is that even when the inner ring 22 is fixedly connected to the hub 3a by the caulking portion 9 provided at the inner end of the hub 3a, the drive shaft is required to effectively secure sufficient durability. Member 13a and hub 3a
The point is that it devised a part of the structure. Since the configuration and operation of the other parts are almost the same as those of the conventional structure shown in FIG. 5, the same parts are denoted by the same reference numerals, and duplicate description is omitted or simplified. The following description focuses on parts and parts different from the above-described conventional structure.

In the case of this embodiment, the outer ring 1 which does not rotate while being supported by the suspension device has a mounting flange 33 formed on the outer peripheral surface for supporting the suspension device. The inner race 22 having the second inner raceway 8 formed on its outer peripheral surface is fitted on a small-diameter step portion 23 formed on the outer peripheral surface of a portion near the inner end of the hub 3a, and is formed on the inner end of the hub 3a. A portion of the cylindrical portion 10 protruding from the inner end face of the inner ring 22 is fixed to the hub 3a by a caulking portion 9 formed by plastically deforming diametrically outward. In this embodiment, the first inner raceway 6 is formed directly on the outer peripheral surface of the intermediate portion of the hub 3a. Further, between the outer end surface of the housing portion 15 constituting the drive shaft member 13a and the inner end surface of the hub 3a,
By bending and forming a metal plate made of spring steel, etc.
An elastic ring 27 having a V-shaped cross section and formed entirely in an annular or partially annular shape is sandwiched while being elastically compressed in the axial direction.

On the other hand, the spline shaft 14a constituting the drive shaft member 13a has a locking groove
4 is formed over the entire circumference, and the locking groove 24 and the hub 3
a with a step surface 25 formed in a portion of the inner peripheral surface near the outer end,
A retaining ring 26 having a rectangular cross-section and being entirely annular is bridged. The diameter of the retaining ring 26 can be elastically expanded and contracted by forming an elastic metal such as spring steel or stainless spring steel into a substantially C-shaped open circle. Such a retaining ring 26 is elastically enlarged in diameter, passes through the outer peripheral surface of the distal end of the spline shaft 14a, and is then elastically reduced (restored) in diameter to thereby form the hub 3a. Of the spline hole 12 provided at the center of the spline hole 12 and the stepped surface 25. By bridging the retaining ring 26 in this manner, the spline shaft 14a is prevented from falling out of the spline hole 12. Therefore, in the case of this example, the retaining ring 26, the step surface 25, and the locking groove 24 constitute a retaining mechanism described in claims.

Further, in this state, as described above, the elastic ring 27 is elastically held between the inner end surface of the hub 3a and the outer end surface of the housing portion 15. Therefore, the elastic ring 27 is provided between the hub 3a and the housing portion 15.
At this time, elasticity is applied in a direction to separate the inner end surface of the hub 3a and the outer end surface of the housing portion 15 from each other. And
The male spline portion 20 provided on the outer peripheral surface of the spline shaft 14a and the female spline portion 19 provided on the inner peripheral surface of the spline hole 12 are prevented from being relatively displaced in the axial direction. Therefore, both spline portions 20 and 19 can be hardly worn. For this reason, it is preferable that the elasticity of the elastic ring 27 be greater than the thrust load generated at the tripod type constant velocity joint provided on the differential gear side. Further, a cap 28 is fitted and fixed to an outer end opening of the hub 3a to close the outer end opening, and a spline engagement between the male spline portion 20 and the female spline portion 19 from the outer end opening. It prevents foreign matters such as rainwater and dust from entering the part. A seal ring 3 is provided between an inner peripheral surface of both ends of the outer race 1 and an outer peripheral surface of an intermediate portion of the hub 3a and an outer peripheral surface of an inner end of the inner race 22.
4 and 34 are provided to close the openings at both ends of the space in which the plurality of rolling elements 11 and 11 are installed.

In particular, in the case of the wheel drive bearing unit according to the present invention, a part of the spline shaft 14a, which is deviated axially inward from the male spline part 20 in the axial direction, has a cylindrical part as described in the claims. , A large-diameter cylindrical portion 29 is provided. The large-diameter cylindrical portion 29 and the male spline portion 2
A small-diameter cylindrical portion 30 having a diameter smaller than that of the large-diameter cylindrical portion 29 is provided in a portion between zero and zero. Further, with the caulked portion 9 formed at the inner end of the hub 3a, the caulked portion 9 is formed closer to the female spline portion 19 than the caulked portion 9.
The base half (the left half in FIG. 1) of the cylindrical portion 10 is a cylindrical portion described in claims, and a part of the inner peripheral surface of the base half and the outer peripheral surface of the large-diameter cylindrical portion 29. A portion is brought into close contact with a contact or a small gap over the entire circumference. For this reason, in the case of this example, the inner diameter D of the base half of the cylindrical portion 10 is set.
₁₀ and the outer diameter d ₂₉ of the large-diameter cylindrical portion 29 (D ₁₀ −
In a state where d ₂₉ ) is regulated to a range of 0 to 0.2 mm, a part of the large-diameter cylindrical portion 29 is internally fitted to a part of the base half of the cylindrical portion 10 by gap fitting.

With the use of the wheel drive bearing unit, the housing portion 15 and the housing portion 15
When the center axes of the inner ring for the constant velocity joint (not shown) provided inside of the inner ring are inconsistent with each other (the state where the axis intersection angle is not 180 degrees), a predetermined When a torque larger than the magnitude is applied, a part of the outer peripheral surface of the large-diameter cylindrical portion 29 is formed by the bending moment acting on the large-diameter cylindrical portion 29. It touches a part.
In this case, the torque having a predetermined magnitude is, for example, the magnitude of the bending moment acting on the large-diameter cylindrical portion 29 when the torque is changed when the axis intersection angle is a predetermined angle. It is decided appropriately in consideration of. Note that the part of the outer peripheral surface of the large-diameter cylindrical part 29 and the part of the inner peripheral surface of the cylindrical part 10 do not necessarily come into contact immediately after the start of use. The male spline section 20 and the female spline section 1
The object of the present invention is that if the spline engagement portion 9 is familiar (wears) shortly after the start of use and abuts in a state where the backlash of the spline engagement portion is greater than immediately after assembly, Thus, the durability of the wheel drive bearing unit can be ensured.

In the case of this embodiment, the large-diameter cylindrical portion 29
Of the small-diameter cylindrical portion 30 and an outer peripheral surface of the small-diameter cylindrical portion 30 are continuously formed by a curved surface portion 32 having a sufficiently large radius of curvature and having an arc-shaped cross section, thereby preventing excessive stress from being concentrated on the intermediate portion. are doing.

The wheel driving shaft of the present invention configured as described above
According to the receiving unit, the inner ring 22 is connected to the hub 3a.
The fixing is performed by a caulking portion 9 provided at the inner end of the hub 3a.
To ensure sufficient durability
You. This reason will be described with reference to FIG. Shown in the figure
Thus, the wheel drive bearing unit of the present invention
The housing part 15 serving as the outer ring of the
Center axes with the inner ring (not shown) for constant velocity joints
Are not matched, the inner ring for constant velocity joint
From the housing 15 has a torque greater than a predetermined value.
In addition, a bending moment is applied to the inner end of the drive shaft member 13a.
To M₀ Assume that has worked. In this state of the present invention
The drive shaft member 13a is larger than the hub 3a (FIG. 1).
A point A ′ which is a part of the outer peripheral surface of the diameter cylindrical portion 29,
Splice between in section 20 and female spline section 19 (FIG. 1)
At the point B, which is the outer end position of the engagement portion. Soshi
The size of each of the points A ′ and B is F_A ´
And F_B Are acting in opposite directions to each other. the above
The large-diameter cylindrical portion 29 is more axial than the male spline portion 20.
It is provided in the part which deviates inward. Therefore, this male sp
Step between the line portion 20 and the small-diameter cylindrical portion 30
41, the axial distance between the point C and the point A ′.
Assuming that the separation is x, the bending moment M acting on the point C
_C Is M _C = M₀ -F_A 'X. Mentioned earlier
In the case of the conventional structure described above, of the drive shaft member 13a,
Where the stress concentration is large and the strength is the least
At the point C, which is a minute, a curve acting on the drive shaft member 13a
Maximum value of the bending moment M₀ Worked, but in the present invention
Is the bending moment M acting on this point C_C The above maximum value
M₀ Can be kept smaller. Therefore, the present invention
According to the sufficient durability of the entire wheel drive bearing unit
Can secure it.

In addition, in the case of the present invention, the durability is as described above.
The bearing unit for wheel drive has been
There is no increase in size or weight. In addition, actual use
In the use state, strictly speaking, the drive shaft member 13a is
There is no contact only at two points.
The load applied to the driving shaft member 13a is divided into a certain large area.
Become a distributed load. However, such actual use condition
The state is such that the drive shaft member 13a is joined from the hub 3a.
The resultant force of the distributed load acts intensively only at two points
Can be considered as a substitute for
The result is similar to what was done. For this reason, the actual use condition
According to the present invention, sufficient durability is ensured.
Effective. In the illustrated example, the drive shaft member 13a
Outside the large-diameter cylindrical part 29 corresponding to the cylindrical part provided in the intervening part
Corresponds to the peripheral surface and the cylindrical portion provided at the inner end of the hub 3a
The inner peripheral surface of the base half of the cylindrical portion 10
With the face. However, the outer peripheral surface of these large-diameter cylindrical portions 29 and
The inner peripheral surface of the base half of the cylindrical part 10 is limited to such a cylindrical surface.
It does not do. That is, the outer peripheral surface of the large-diameter cylindrical portion 29
A part of the inner peripheral surface of the base half of the cylindrical portion 10
When the contact is made, the large-diameter cylindrical portion 29 and the cylindrical
The load applied to the part 10 is the component force F in the radial direction. _A '(FIG. 2
), The large-diameter cylindrical portion 29
For example, the outer peripheral surface and the inner peripheral surface of the base half of the cylindrical portion 10 are cut off.
It can also be a curved surface or a conical surface, etc.
You. Therefore, the columnar portion and the circle described in the claims of the present invention.
The outer peripheral surface or the inner peripheral surface of the cylindrical portion is
This is a generic term including a curved surface.

Further, in the case of the wheel drive bearing unit of this embodiment, the spline shaft 14a is prevented from falling out of the spline hole 12 by the locking groove 24 formed on the outer peripheral surface near the tip of the spline shaft 14a. This is achieved by bridging a retaining ring 26 with the step surface 25 provided on the hub 3a. Therefore, for example, a screw portion is provided at the tip of the spline shaft 14a, and the outer end surface of the hub 3a is held down by a holding nut screwed and tightened to this screw portion, thereby preventing the spline shaft 14a from coming off. As compared with the structure, the assembling work can be facilitated and the weight can be reduced.

On the other hand, as described above, in the structure in which the spline shaft 14a is prevented from coming off by the tip of the spline shaft 14a and the nut is screwed and tightened, the swaging portion 9 is used.
The inner end surface is strongly pressed against the outer end surface of the housing portion 15 so that these two end surfaces are frictionally engaged with each other, and a part of a bending moment acting on the drive shaft member 13a can be supported by the friction engagement portion. Therefore, in the case of the structure in which the retaining nut is used to prevent the spline shaft 14a from coming off, as compared with the case where the retaining of the spline shaft 14a is carried out by the retaining ring 26 as in the structure of the present embodiment, Stress acting on the cross section including the step portion 41 between the male spline portion 19 and the small-diameter cylindrical portion 30 can be reduced. Therefore, in such a structure, even if the present invention is not applied, the durability of the entire wheel drive bearing unit rarely causes a problem. However, it is possible to further improve the durability by applying the present invention.

Next, FIGS. 3 and 4 show a second example of the embodiment of the present invention. In the case of this example, the spline shaft 14a
Locking groove 24 formed on the outer peripheral surface near the tip of
The cross-sectional shape of the retaining ring 26a that is bridged over the step surface 25 formed near the outer end of the inner peripheral surface of a is shown in detail in FIG. That is, one side surface of the retaining ring 26a (FIGS. 3, 4)
(Left side surface), an inclined surface 35 that is inclined in such a direction that the inner diameter becomes smaller toward the other side in the axial direction (the right side in FIGS. 3 and 4). In contrast, the retaining ring 26
The other side of “a” is a mere flat surface over the entire circumference. Then, the retaining ring 26a is connected to the locking groove 24 and the step surface 25.
In such a state that the retaining ring 26a has elasticity in a direction of contracting its own diameter.
Regulates the diameter in the free state.

The retaining ring 26a as described above is connected to the locking groove 24.
And the stepped surface 25, the inclined surface 35 provided on one side surface of the retaining ring 26a comes into contact with the axially outer end edge of the locking groove 24 and the outer diameter side of the other side surface of the retaining ring 26a. The portion contacts the step surface 25. In this state, the retaining ring 26a has elasticity in a direction to contract its diameter.
Therefore, the inclined surface 35 of the retaining ring 26a and the locking groove 2
A force in a direction orthogonal to the inclined surface 35 acts on the engagement groove 24 from the retaining ring 26a to the contact portion with the axial outer edge of No. 4. The drive shaft member 13a is displaced axially outward with respect to the hub 3a by a component force of the force toward the outside in the axial direction of the drive shaft member 13a. The end face is pressed against the outer end face of the housing part 15. As a result, even when a thrust load in different directions is repeatedly applied during driving of the automobile, the female spline portion 19 provided on the inner peripheral surface of the spline hole 12 and the male spline portion 20 provided on the outer peripheral surface of the spline shaft 14a. By preventing relative displacement in the axial direction, both spline portions 19 and 20 can be hardly worn.

Furthermore, in the case of the present embodiment, in order to prevent the two spline portions 19 and 20 from being relatively displaced in the axial direction, the elastic ring 27 used in the first embodiment described above is used.
(See FIG. 1). For this reason, the number of assembly steps can be reduced due to the reduction in the number of parts. Further, the hub 3
a and the outer end surface of the housing portion 15 are in direct contact with each other, so that the axial dimension of the entire wheel drive bearing unit can be reduced, and the weight of the wheel drive bearing unit can be reduced. It can also contribute to the development.

When the spline shaft 14a is pulled out from the hub 3a when the wheel drive bearing unit of the present embodiment having the above-described configuration is used, the axial outer end of the locking groove 24 is applied. A force in a direction perpendicular to the inclined surface 35 is applied to the retaining ring 26a from the edge. This power is
Since the retaining ring 26a has a component force directed outward in the diameter direction of the retaining ring 26a, if the component force is excessive, the retaining ring 26a may fall out of the locking groove 24 in the radial direction.
Therefore, in the case of the present example, in order to prevent the falling-off, the static friction force acting on the contact portion between the inner surface of the retaining ring 26a and the step surface 25 corresponds to the diametrically outward direction. Design to be greater than force. That is, the retaining ring 26a
The angle of inclination of the inclined surface 35 with respect to an imaginary plane orthogonal to the central axis of is defined as α, the coefficient of static friction at the contact portion between the inner surface of the retaining ring 26a and the step surface 24 is designated as μ,
It is assumed that the radial elastic resistance of the retaining ring 26a is so small as to be negligible (for the purpose of design with a margin). In this case, the radial component of the resultant force of the static friction force acting on the contact portions between the inner and outer sides of the retaining ring 26a and the axial outer edges of the step surfaces 25 and the locking grooves 24 is the diameter Α ≦ 2 · ta so that it is larger than the component force directed outward
It is regulated to satisfy the relation of n ^-1 μ.

In this embodiment, a seal ring 36 is provided between the inner end of the outer race 1 and the outer peripheral surface of the outer end of the housing 15, and a plurality of rolling elements 11, 11 are provided. The inner end opening of the space and the inner end of the space communicating with the spline engagement portion between the male spline portion 20 and the female spline portion 19 are sealed, respectively. The seal ring 36
Is a metal core 37 having a crank shape in cross section and formed entirely in an annular shape.
A seal lip 38 made of an elastic material such as an elastomer such as rubber is attached to the inner peripheral edge of the inner peripheral edge of the inner peripheral portion over the entire periphery. Such a seal ring 36 secures the core bar 37 to the inner end of the outer ring 1 by external fitting and fixes the inner peripheral edge of the seal lip 38 to the outer peripheral surface of the outer end of the housing portion 15. Sliding contact is made over the entire circumference. In the illustrated example, a garter spring 39 is externally fitted to the outer peripheral surface of the seal lip 38, and the inner peripheral edge of the seal lip 38 is securely attached to the outer peripheral surface of the outer end of the housing portion 15 over the entire circumference. In addition, sliding contact is performed with an appropriate contact pressure so that good sealing performance can be obtained. Other configurations and operations are the same as those of the above-described first example.

In each of the above examples, the spline shaft 14
a from the spline hole 12, a step surface 25 provided on the inner peripheral surface of the hub 3 a near the outer end, and a locking groove 24 provided on the outer peripheral surface of the spline shaft 14 a near the tip end.
At the same time, this is achieved by bridging the retaining ring 26 (26a). However, the present invention is not limited to such a structure. An outer locking groove is formed on a part of the inner peripheral surface of the spline hole 12 over the entire circumference, and the outer locking groove is formed with the outer locking groove. A variety of retaining means, such as preventing the spline shaft 14a from slipping off, by hooking an annular retaining ring around an inner locking groove formed all around the part of the outer peripheral surface of the spline shaft 14a. Structure can be adopted.

[0032]

The bearing unit for driving a wheel according to the present invention is constructed and operated as described above. Therefore, even when the inner ring is fixedly connected to the hub by the caulking portion provided at the inner end of the hub, it is sufficient. Effective durability.

[Brief description of the drawings]

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

FIG. 2 is a view for explaining a distribution state of a bending moment acting on a drive shaft member in the present invention.

FIG. 3 is a half sectional view showing a second example of the embodiment of the present invention.

FIG. 4 is a partially enlarged sectional view of a retaining ring used in the second example.

FIG. 5 is a half sectional view showing one example of a conventional structure.

FIG. 6 is a view for explaining a distribution state of a bending moment acting on a drive shaft member in a conventional structure.

[Explanation of symbols]

 Reference Signs List 1 outer ring 2 outer ring track 3, 3a hub 4 mounting flange 5 knuckle 6 first inner ring track 7a first inner ring 7b second inner ring 8 second inner ring track 9 caulked portion 10 cylindrical portion 11 rolling element 12 spline hole 13, 13a Drive shaft member 14, 14a Spline shaft 15 Housing portion 16 Outer track 17 Coupling member 18 Encoder 19 Female spline portion 20 Male spline portion 21 Space 22 Inner ring 23 Small diameter step portion 24 Locking groove 25 Step surface 26, 26a Retaining ring 27 Elasticity Ring 28 Cap 29 Large-diameter cylindrical portion 30 Small-diameter cylindrical portion 32 Curved surface portion 33 Mounting flange 34 Seal ring 35 Inclined surface 36 Seal ring 37 Core metal 38 Seal lip 39 Garter spring 40 Cylindrical portion 41 Step surface 42 Stepped surface 42

Claims (1)

[Claims] 1. An outer ring which has a double row of outer ring raceways on an inner peripheral surface and does not rotate even during use, and a mounting flange for supporting a wheel at a portion near an outer end of an outer peripheral surface are directly or intermediately provided. A first inner raceway was provided via a separate inner race, a spline hole was provided at the center, and an inner race having a second inner raceway formed on its outer peripheral surface was fitted around the inner end of the outer peripheral surface. A hub, a plurality of rolling elements rotatably provided between the outer raceways and the first and second inner raceways, and a spline shaft engaged with the spline hole are provided at an outer end. A drive shaft member having an inner end serving as a housing portion serving as an outer ring of a constant velocity joint, and a drive shaft member provided between the drive shaft member and the hub to prevent the spline shaft from falling out of the spline hole. With a retaining mechanism, at the inner end of the hub, The inner end surface of the inner ring is held down by a caulking portion formed by plastically deforming a portion projecting from the inner end surface of the inner ring, which is externally fitted to the inner end portion of the outer peripheral surface of the hub, in a radially outward direction. In the wheel drive unit fixedly connected to the hub, a part of the drive shaft member,
A cylindrical portion provided at a portion deviated inward in the axial direction from the male spline portion provided on the outer peripheral surface of the spline shaft, and at least a part of the inner peripheral surface at the inner end of the hub, A cylindrical portion provided so as to face the outer peripheral surface of the columnar portion, and with the use of the wheel drive bearing unit, a housing portion serving as an outer ring of the constant velocity joint, and a constant velocity also serving as an inner ring. In a state where the center axes of the inner ring for the joint are not coincident with each other, when a torque of a predetermined magnitude or more is applied to the housing portion from the inner ring for the constant velocity joint, a part of the outer peripheral surface of the cylindrical portion is formed. Abuts against a part of the inner peripheral surface of the cylindrical portion.