JP2002002210A - Bearing unit for wheel drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a structure fully ensuring strength of a section which forms a retaining groove 40 to retain an O-ring 39 and minimizing steering moment. SOLUTION: A hub 4a of this unit is provided with a convex curve surface 45 inclining toward a direction with its inside diameter enlarged as it directs axially inward, in its inner end section of inner circumference. In the unit, a slope section 41 inclined to the direction in which the diameter is enlarging toward inner axial direction is formed on an area diametrically-faced the convex curve surface 45 in the outer circumference of a spline shaft 17a base end section. A retaining groove 40 is formed on midway of this slope section 41 to elastically compress an O-ring 39 between the inside of this retaining groove 40 and the convex curve surface 45. This prevents the diameter of section forming the retaining groove 40 from significantly being lessened as well as prevents the axial directional dimensions of a seal section configured including this retaining groove 40 from being increased to solve the above problems.

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. 4 shows a general wheel drive bearing unit combining the wheel support bearing unit 1 and the constant velocity joint 2 for such a purpose.

[0003] Of these, the wheel supporting bearing unit 1 is
A hub 4 and an inner ring 5 are rotatably supported on the inner diameter side of the outer ring 3 via a plurality of rolling elements 6, 6. Of these, the outer race 3 is fixed to a knuckle 8 (see FIG. 5 described later) constituting a suspension by a first flange 7 provided on an outer peripheral surface thereof, and does not rotate during use. Also, double rows of outer raceways 9, 9 are provided on the inner peripheral surface of the outer race 3, and the hub 4 and the inner race 5 are rotatably supported concentrically with the outer race 3 on the inner diameter side of the outer race 3. are doing.

[0004] Of these, the hub 4 is used to support wheels at a portion closer to the outer end of the outer peripheral surface (the end which is the outer side in the width direction of the vehicle when assembled to the vehicle, the left end in FIGS. 1 to 5). A second flange 10 is provided. Also, a first inner raceway 11 is formed at an intermediate portion of the outer peripheral surface of the hub 4, and an inner end thereof (an end which is a center side in the width direction of the vehicle when assembled to the automobile; ) Part formed in the small diameter step 1
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 an outer ring 15 for a constant velocity joint, an inner ring 16 for a constant velocity joint, 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 in the outer half of the drive shaft member 18 and is freely engageable with the spline hole 14. The constant velocity joint outer ring 15 is provided in the inner half 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. Further, the inner race 16 for a constant velocity joint has a second spline hole 20 at a central portion, and inner engagement grooves 21, 21 at portions corresponding to the outer engagement grooves 19, 19 on the outer peripheral surface thereof, respectively. It is formed at right angles to the circumferential direction. And, each of these inner engagement grooves 21, 2
1 and the outer engagement grooves 19, 19, the ball 22,
22 is provided so as to roll freely along each of the engagement grooves 21 and 19 while being held by the holder 23. The shape and the like of each component of the constant velocity joint 2 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.

The above-described constant velocity joint 2 and the above-described wheel supporting rolling bearing unit 1 insert the spline shaft 17 into the spline hole 14 of the hub 4 from inside to outside. Then, a nut 25 is screwed into a male screw portion 24 provided at a portion protruding from the outer end surface of the hub 4 at the outer end portion of the spline shaft 17, and the nut 25 is further tightened to be connected and fixed to each other. In this state, the inner end face of the inner ring 5 comes into contact with the outer end face of the outer ring 15 for a constant velocity joint, so that the inner ring 5 is not displaced in the direction of coming out of the small diameter step portion 12. At the same time, an appropriate preload is applied to each of the rolling elements 6,6.

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). Therefore, the drive shaft 26 rotates at a constant speed when the vehicle is running, and a thrust load in both directions in the axial direction is repeatedly applied with the rotation based on the resistance of the tripod-type constant velocity joint.

In the vehicle wheel drive device shown in FIG. 4, the wheel supporting rolling bearing unit 1 and the constant velocity joint 2 are connected and fixed based on the screwing and tightening of the male screw portion 24 and the nut 25. Weight increases. That is, the male screw portion 24 is attached to the spline shaft 17 on the constant velocity joint 2 side.
The length of the spline shaft 17 needs to be increased by the provision of the nut, and the nut 25 is required. Because of this,
The axial dimension and weight of the vehicle wheel drive device are increased by the amount of the male screw portion 24 and the nut 25.

On the other hand, US Pat. No. 4,881,842
As shown in FIG. 5, the specification discloses that a wheel support bearing unit and a constant velocity joint are connected and fixed with a simpler structure to reduce the axial dimension and reduce the weight. A drive bearing unit is described. Also in the case of the second example of the conventional structure shown in FIG. 5, the hub 4 is rotatably supported by the rolling elements 6, 6 arranged in a double row inside the outer ring 3 fixed to the knuckle 8. The spline shaft 17 of the drive shaft member 18a is spline-engaged with the spline hole 14 formed in the center of the hub 4. 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. The spline shaft 17 is prevented from slipping out of the hub 4 by a retaining ring 33 locked in a locking groove 32 formed in a portion of the spline shaft 17 near the front end of the outer peripheral surface. 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, so that the spline shaft 17 and the hub 4 rattle in the axial direction. We are trying to prevent it. In the case of the second example of such a conventional structure, the coupling between the wheel supporting bearing unit 1a and the constant velocity joint 2a is performed by the retaining ring 33.
The overall size and weight of the vehicle wheel drive device can be reduced.

Incidentally, as in the second example of the conventional structure described above, the wheel supporting bearing unit 1a and the constant velocity
When the connection with the hub 4 is made by the retaining ring 33,
A gap is formed between the inner end surface of the outer ring 15 and the outer end surface of the outer race 15 for a constant velocity joint. The existence of such a gap causes axial play in the spline engagement portion between the spline hole 14 and the spline shaft 17 during operation. Therefore, in the case of the second example of the conventional structure shown in FIG. 5 described above, the elastic ring 34 is sandwiched between the inner end surface of the hub 4 and the outer end surface of the outer race 15 for constant velocity joint, The above-mentioned axial play is prevented. However, even when such an elastic ring 34 is provided, the elastic displacement of the elastic ring 34 in the axial direction causes a relative displacement in the axial direction at the spline engagement portion.

Therefore, even when the spline engaging portion is displaced in the axial direction in this way, the spline engaging portion is worn and a circumferential gap is generated in the spline engaging portion, or It is necessary to prevent generation of abnormal noise due to friction in the axial direction and the like. At the same time, foreign matter such as rainwater enters the spline engagement portion from the outside,
It is necessary to prevent the inconvenience that the spline engagement portion is rusted and the spline shaft 17 cannot be pulled out from the spline hole 14 when replacing parts. For this purpose, grease is sealed in the spline engagement part,
The spline engagement portion is lubricated, and the space in which the spline engagement portion is installed is sealed to prevent the grease from leaking to the outside and to prevent foreign matter such as rainwater from entering from the outside. There is a need. As a structure for sealing the space in which the spline engagement portion is installed in this way, for example, while closing the outer end opening of this space with a cap,
It is conceivable to adopt a structure in which a gap existing on the inner end side of this space is closed by a seal ring.

[0012]

In the case of the second example of the conventional structure as described above, the size and weight can be reduced, but it is difficult to secure sufficient durability as it is. The reason will be described below. During operation of the vehicle wheel drive device as shown in FIGS. 4 and 5, the center axes of the constant velocity joint outer ring 15 and the constant velocity joint inner ring 16 constituting the constant velocity joints 2 and 2a are not coincident with each other. State (axis intersection angle is 1
When the driving force (torque) is transmitted via the constant velocity joints 2 and 2a in a state where the constant velocity joints are not 80 degrees, the balls 22 and 22 constituting the constant velocity joints 2 and 2a and the inner engagement grooves 21 are formed. , 21 and the outer engagement grooves 19, 19 no longer exist on the same plane perpendicular to the axis. For this reason, not only a torsional torque but also a bending moment acts on the drive shaft members 18 and 18a. Further, when the pitch of the outer and inner engagement grooves 19 and 21 is not uniform due to a manufacturing error or the like, if the outer and inner engagement grooves 19 and 21 are not uniform.
19 and the inner engagement grooves 21, 21 and the respective balls 22, 2
A component in the radial load direction is also generated as a resultant of the contact load with No. 2. When a radial load direction component based on such a resultant force is generated, not only the above-described torsional torque and bending moment are applied to the cross sections of the drive shaft members 18 and 18a, but also the constant velocity joint is applied to the radial load. 2
The bending moment multiplied by the axial distance from the ball 22 that constitutes the above is applied.

On the other hand, the weakest part of the drive shaft members 18 and 18a in terms of strength is the base end of the spline shaft 17. For this reason, it is necessary to ensure sufficient durability of the base end of the spline shaft 17 against the load of the torsional torsion torque and the bending moment as described above. In this regard, in the case of a structure in which the wheel supporting bearing unit 1 and the constant velocity joint 2 are connected and fixed using the nut 25 as shown in FIG. 4 described above, the outer end surface of the hub 4 and the nut 2
The inner surface of the washer 43 attached to the inner ring 5 and the inner end surface of the inner race 5 and the outer end surface of the constant velocity joint outer race 15 are in strong contact with each other (frictional engagement). As a result, a substantial portion of the torsional torque and the bending moment is supported by each of the contact surfaces, so that the torsional torque and the bending moment applied to the base end portion of the spline shaft 17 are reduced accordingly.
Therefore, the durability of the base end of the spline shaft 17 can be ensured by the reduced load.

On the other hand, as shown in FIG.
In the case of a structure in which the wheel supporting bearing unit 1a and the constant velocity joint 2a are connected and fixed using the retaining ring 33, both the inner surface of the retaining ring 33 and the outer end surface of the hub 4 and the inner end surface of the hub 4 are used. And the outer end surface of the outer race 15 for a constant velocity joint,
Neither of them makes strong contact (frictional engagement). Since the contact pressure based on the elasticity of the elastic ring 34 is limited (small), the frictional engagement force of the contact surface is small, and the extent to which this portion supports the torsional torque and bending moment is extremely limited. It's just something. Therefore, most of the torsional torque and the bending moment are applied to the base end of the spline shaft 17. Further, in the case of the structure using the retaining ring 33, it is necessary to seal the spline engagement portion between the spline shaft 17 and the spline hole 14, as described above. For this purpose, the seal ring is elastically compressed between a cylindrical inner peripheral surface provided near the inner end of the hub 4 and a cylindrical outer peripheral surface provided at the base end of the spline shaft 17. Therefore, if a locking groove for locking the seal ring is formed over the entire circumference of a cylindrical outer peripheral surface provided at a base end portion of the spline shaft 17, the locking groove is formed. The diameter of the spline shaft 17 is reduced in the formed portion. Therefore, in the case of the structure using the retaining ring 33, the position where the locking groove is formed is adjusted to the cylindrical outer peripheral surface (the inner end portion of the hub 4) provided at the base end portion of the spline shaft 17 as described above. (The portion facing the cylindrical inner peripheral surface provided in the above) in the diametrical direction), it may be difficult to sufficiently secure the durability of the portion where the locking groove is formed.

In order to avoid the disadvantage that the diameter of the spline shaft 17 is reduced in the portion where the locking groove is formed, for example, the locking groove is formed on the outer end surface of the outer race 15 for a constant velocity joint. Things are possible. In this case, the seal ring locked in the locking groove is compressed in the axial direction between the inner surface of the locking groove and the inner end surface of the hub 4. However, when the locking groove is formed on the outer end surface of the outer race 15 for the constant velocity joint, the outer race for the constant velocity joint is secured in order to secure the strength of the outer end of the outer race 15 for the constant velocity joint. Fifteen
Must be increased by the axial dimension (depth dimension) of the locking groove. As a result, the axial distance between the center of displacement of the constant velocity joint 2a, which is the radius of rotation of the wheel at the time of steering, and the center of the ground contact surface of the tire supported and fixed to the hub 4 is increased, and the steering moment during driving is increased. It will be difficult to respond to requests to reduce the size. In view of the above-described circumstances, a wheel drive bearing unit of the present invention has a structure in which a wheel support bearing unit and a constant velocity joint are coupled by a retaining ring, and a locking groove for locking a seal ring. The invention has been made in order to realize a structure in which the strength of the drive shaft member can be sufficiently ensured at the portion where is formed and the steering moment does not increase.

[0016]

According to the present invention, there is provided a vehicle wheel drive apparatus comprising: an outer ring, a hub, a rolling element, a drive shaft member,
And 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.
Further, 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 raceway directly at the intermediate portion or via a separate inner ring, and a second flange at the center portion. One spline hole is provided, and an inner race having a second inner raceway formed on the outer peripheral surface is fixedly fitted to the outer peripheral surface near the inner end of the outer peripheral surface. Further, a plurality of rolling elements are provided between each of the outer raceways and the first and second inner raceways so as to freely roll. In the drive shaft member, a spline shaft that engages with the first 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 diameter side engaging portion provided on an outer peripheral surface of an outer end portion of the spline shaft and an outer diameter side provided on a portion of the inner peripheral surface of the hub opposed to the inner diameter side engaging portion. The spline shaft is hung between the engaging portions to prevent the spline shaft from falling out of the spline hole.

In particular, in the wheel drive bearing unit according to the present invention, the inside of the hub is provided between the portion where the spline hole is formed on the inner peripheral surface of the hub and the inner end edge of the hub. A portion is provided that is inclined in a direction in which the inner diameter increases toward the end. At the same time, a seal ring is locked in a locking groove formed over the entire circumference in a portion of the inner end portion outer peripheral surface of the spline shaft facing the inclined portion with respect to the diametrical direction. The gap existing between the drive shaft member and the hub is closed by elastically compressing between the inner surface of the locking groove and the inclined portion.

[0018]

According to the wheel drive bearing unit of the present invention configured as described above, even if the connection between the wheel support bearing unit and the constant velocity joint is made by the retaining ring, the spline shaft constituting the drive shaft member can be used. With sufficient strength, sufficient durability can be ensured regardless of the torsional torque and bending moment repeatedly applied during use. That is, in the case of the present invention, between the portion where the spline hole is formed on the inner peripheral surface of the hub and the inner end edge portion of the hub, the inner diameter is inclined in such a direction that the inner diameter increases toward the inner end side of the hub. The part which did is provided. A locking groove for locking the seal ring over the entire circumference is formed in a portion of the inner end outer peripheral surface of the spline shaft which is diametrically opposed to the inclined portion. Of the outer peripheral surface of the inner end of the spline shaft, a portion diametrically opposed to the inclined portion is another portion of the outer peripheral surface of the inner end of the spline shaft (an outer portion of the outer surface of the portion opposed to the inclined portion). This is a part whose diameter can be made larger than that of the part. Therefore, in the case of the present invention in which the locking groove is formed in a portion where the diameter of the inner end of the spline shaft can be increased, the diameter of the spline shaft is prevented from being significantly reduced in the portion where the locking groove is formed. The strength of the portion where the locking groove is formed can be sufficiently ensured. Further, in the case of the present invention, since the locking groove is formed in a portion diametrically opposed to the inclined portion on the outer peripheral surface of the inner end portion of the spline shaft, The axial dimension of the seal structure formed by the locking groove can be reduced as compared with the case where the seal joint is formed on the outer end surface (a flat step portion orthogonal to the axial direction) of the outer ring for the speed joint. Therefore, the axial dimension of the outer end of the outer race for a constant velocity joint can be prevented from increasing due to the provision of the seal structure. As a result, the turning radius of the wheels during steering can be reduced, and the steering moment can be reduced.

[0019]

FIG. 1 shows a first embodiment of the present invention. The feature of the present invention lies in the structure of a portion for sealing a gap on the inner end side of a space in which a spline engagement portion between the spline shaft 17a and the spline hole 14 is installed.
Since the structure and operation of the other parts are almost the same as those of the second example of the conventional structure shown in FIG. 5, the same reference numerals are given to the same parts, and the overlapping description will be omitted. The following description focuses on the characteristic portions and the portions different from the second example of the conventional structure.

In the case of this embodiment, the inner race 5 having the second inner raceway 13 formed on the outer peripheral surface thereof is externally fitted and fixed to a small-diameter step 12 formed at the inner end of the hub 4a. In this state, a caulking portion 35 is formed at the inner end of the hub 4a in order to prevent the inner ring 5 from coming out of the small diameter step portion 12. That is, a cylindrical portion is formed at the inner end of the hub 4a, and a portion protruding from the inner end edge of the inner race 5 at the tip of the cylindrical portion is plastically deformed radially outward to form the caulking portion 3
The inner end surface of the inner ring 5 is pressed down by the caulking portion 35.

In the case of this embodiment, the spline shaft 17a
Is not provided with a locking portion 31 (see FIG. 5) for locking the drawing tool. The omission of the locking portion 31 shortens the axial dimension of the spline shaft 17a, thereby reducing the size and weight. In this case,
If it is necessary to pull the spline shaft 17a into the inside of the spline hole 14, the leading end of the drawing tool is engaged with an engaging hole (not shown) formed in the leading end surface of the spline shaft 17a (for example, a screw hole). Screw). or,
In the case of this example, a part of the center hole of the hub 4a adjacent to the outer end side of the spline hole 14 is concentric with the spline hole 14 and has an inner diameter of the spline hole 1.
4 is provided with a circular hole 36 which is the same as or slightly larger than the groove bottom diameter. An outer diameter side engaging portion for engaging the outer diameter half of the retaining ring 33 with a continuous portion between the outer edge of the spline hole 14 and the inner edge of the circular hole 36. Stop 3
7 are formed.

In the case of the present embodiment, the retaining ring 33 is provided with a locking groove formed on the outer peripheral surface of the spline shaft 17a near the front end thereof before the spline shaft 17a is inserted into the spline hole 14. 32. When the spline shaft 17a is inserted into the spline hole 14, the retaining ring 33 passes through the spline hole 14 while elastically reducing its diameter. Then, after passing through, it is elastically restored, and as described above, the locking groove 32 and the locking step portion 3 are formed.
It is hung between 7. In order to perform such mounting work, the depth of the locking groove 32 is sufficiently ensured (the retaining ring 3
3 is larger than the thickness in the radial direction).

In the case of this embodiment, the spline shaft 17a
Both sides in the axial direction of the space in which the spline engagement portion between the shaft and the spline hole 14 is installed are closed by a cap 38 and an O-ring 39 as a seal ring. This prevents the grease sealed in this space from leaking to the outside and prevents foreign substances such as dust and rainwater from entering the space from outside. The cap 38 is formed in a crank shape in cross section by pressing a metal plate such as a stainless steel plate, and covers the outer end opening of the space. Such a cap 38 is provided on the spline shaft 1.
The hub 4a is internally fitted and fixed to a portion near the outer end of the hub 4a in a state where the hub 4a is closely opposed to the distal end surface of the hub 4a.

The O-ring 39 is formed on the outer peripheral surface of the base end of the spline shaft 17a.
In a state where the space is locked to 0, the gap on the inner end side of the space is closed. In particular, in the case of this example, the inner end of the inner peripheral surface of the hub 4a is formed along with the formation of the caulking portion 35.
A convex curved surface portion 45 is provided which is inclined in a direction in which the inner diameter increases toward the inner end side of the hub 4a. At the same time, in the outer peripheral surface of the base end portion of the spline shaft 17a, a concave portion inclined in a direction in which the diameter increases toward the base end side of the spline shaft 17a is formed in a portion facing the convex curved surface portion 45 in the diameter direction. A curved inclined surface portion 41 is provided. Then, the locking groove 40 is connected to the inclined surface portion 4.
1 is formed at an intermediate portion in the axial direction. Such a locking groove 40
The O-ring 39 is elastically compressed between the inner surface of the locking groove 40 and the convex curved portion.

Of the base end of the spline shaft 17a,
The diameter of a portion corresponding to the inclined surface portion 41 is larger than the diameter of another portion (a portion on the tip side of the inclined surface portion 41). In other words, in the case of the present example in which the above-described convex curved surface portion 45 is provided at the inner end of the inner peripheral surface of the hub 4a, the convex curved surface in the diametric direction is included in the outer peripheral surface of the base end portion of the spline shaft 17a. The inclined surface portion 41 having a large diameter can be formed in a portion facing the portion 45 as described above. In this case,
By forming the locking groove 40 on the inclined surface portion 41 having a large diameter in this way, it is possible to prevent the diameter of the spline shaft 17a from becoming too small at the portion where the locking groove 40 is formed. Of the locking grooves 40,
The strength of the portion where is formed can be sufficiently ensured.

In the case of this embodiment, the depth direction of the locking groove 40 (the direction of the dashed line α in FIG. 1) is the tangent of the intermediate portion of the inclined surface 41, which is the part where the locking groove 40 is formed. The direction is perpendicular to the direction. Thereby, this locking groove 4
In comparison with the case where the depth direction of 0 is matched with the diameter direction of the spline shaft 17a, the diameter of the bottom of the locking groove 40 is increased, and the strength of the portion where the locking groove 40 is formed is sufficiently increased. So that they can be secured. In the case of this example, the outer ring 15 for a constant velocity joint, which constitutes the drive shaft member 18b,
The thickness T ₄₀ of the portion corresponding to the engaging groove 40, greater than the thickness t of the portion corresponding to the inner peripheral edge of the outer end face of the constant velocity joint outer ring 15 (T _40> t) to, This prevents the outer race 15 for a constant velocity joint from being easily broken at a portion corresponding to the locking groove 40.

The O-ring 39, which is locked in the locking groove 40 as described above, is provided on an inner surface of the locking groove 40 and an inner end of the inner peripheral surface of the hub 4a in an assembled state as shown. It is elastically compressed with the curved portion 45. In the case of this example, the caulking portion 3
The dimensions of each part are regulated so that a minute gap 44 is formed between the inner end surface of the outer ring 5 and the outer end surface of the outer race 15 for a constant velocity joint. In the case of this example, the inclined surface portion 41 (the locking groove 40) and the convex curved surface portion 45, which elastically compress the O-ring 39, have a larger radial dimension toward the inside in the axial direction. The surface is inclined in the direction of Because of this,
The O-ring 39 is compressed between the two surfaces in two directions, a radial direction (diameter direction) and an axial direction (axial direction). Therefore, the O-ring 39
Is capable of supporting an axial load acting between the two surfaces while being elastically compressed between the two surfaces. Therefore, in the case of this example, when the constant velocity joint outer ring 15 vibrates in the axial direction during operation, the vibration is absorbed by the O-ring 39, and the inner end face of the caulking portion 35 and the constant velocity The small gap 44 is maintained between the outer end surface of the joint outer ring 15 and the outer end surface. By maintaining such a minute gap 44, generation of abnormal noise due to metal contact between the both end surfaces is prevented.

As described above, according to the wheel drive bearing unit of the present embodiment, the strength of the portion of the base end of the spline shaft 17 where the locking groove 40 for locking the O-ring 39 is formed is reduced. We can secure enough. In addition, since the locking groove 40 is formed in the inclined surface portion 41, the locking groove 40 is formed on the outer end surface of the outer race 15 for a constant velocity joint (a flat step portion orthogonal to the axial direction). The dimension of the locking groove 40 in the axial direction can be reduced as compared with the case of FIG. Accordingly, the axial dimension of the outer end portion of the outer ring 15 for constant velocity joint can be prevented from increasing due to the formation of the locking groove 40. As a result, the turning radius of the wheel at the time of steering is
By reducing the axial distance from the center of displacement of the constant velocity joint 2b to the center of the ground contact surface of a tire (not shown) supported and fixed to the hub 4a, the steering moment can be reduced.

FIG. 2 shows a second embodiment of the present invention.
An example is shown. In the case of this example, the inner diameter of the circular hole 36 provided adjacent to the outer end side of the spline hole 14 is sufficiently larger than the inner diameter of the spline hole 14. In the case of the present example in which the inner diameter of the circular hole 36 is increased in this manner, the locking groove 32 formed on the outer peripheral surface of the tip end of the spline shaft 17a and the locking step 37 provided on the outer edge of the spline hole 14 The mounting work of the retaining ring 33 to be bridged between the spline holes 1
After the spline shaft 17a is completely inserted into the spline shaft 4, the operation is performed from the outer end side of the spline hole 14. The operation of mounting the cap 38 for closing the outer end opening of the space in which the spline engagement portion between the spline hole 14 and the spline shaft 17a is installed is performed after the operation of mounting the retaining ring 33 is completed.

In the case of this embodiment, the hub 4a is provided on the outer peripheral surface of the base end of the spline shaft 17a, which is a portion diametrically opposed to the convex curved surface portion 45 provided on the inner end of the inner peripheral surface of the hub 4a. The depth direction (the direction of the chain line β in FIG. 2) of the locking groove 40a formed in the inclined surface portion 41 is made to coincide with the diameter direction of the spline shaft 17a. In the case of the present example, the O-ring 39 to be locked in the locking groove 40a has a cross-sectional diameter dimension so that the groove bottom diameter of the locking groove 40a formed in such a direction does not need to be too small. However, a small one of about 1 to 2 mm is used. This prevents the diameter of the spline shaft 17a from becoming too small in the portion where the locking groove 40a is formed, and sufficiently secures the strength of the portion where the locking groove 40a is formed.

In the case of this embodiment, the dimensions of each part are secured so as to secure a minute gap 44 between the inner end face of the caulking part 35 provided at the inner end of the hub 4a and the outer end face of the outer race 15 for the constant velocity joint. In order to facilitate the regulation, the inner end surface of the caulking portion 35 is subjected to surface pressing to form a flat surface portion 42 parallel to the outer end surface of the outer race 15 for the constant velocity joint on the inner end surface. Such a flat surface portion 42 is the first surface portion shown in FIG.
It can also be provided in the example structure. Other configurations and operations are the same as those of the above-described first example.

FIG. 3 shows a third embodiment of the present invention.
An example is shown. In the case of this example, the spline shaft 17a
A cylindrical surface portion 46 is provided at an intermediate portion in the axial direction of the inclined surface portion 41 provided on the outer peripheral surface of the base end portion (a portion diametrically opposed to the convex curved surface portion 45 provided at the inner end portion of the inner peripheral surface of the hub 4a).
A locking groove 40a for locking the O-ring 30 is formed in an intermediate portion of the cylindrical surface portion 46. Also in the case of this example, the cylindrical surface portion 46 as described above has a diameter larger than the other portion of the base end portion of the spline shaft 17a (a portion on the distal end side than the portion diametrically opposed to the convex curved surface portion 45). Is the large part. Therefore, also in the case of this example, it is possible to prevent the diameter of the spline shaft 17 from becoming too small in the portion where the locking groove 40a is formed, and it is possible to sufficiently secure the strength of the portion where the locking groove 40a is formed. Other configurations and operations are
This is the same as in the first and second examples described above.

In each of the above-described examples, the case where the O-ring 39 is used as a seal ring for closing the gap on the inner end side of the space in which the spline engagement portion is installed is shown. As such a seal ring, for example, those having various shapes such as an X-ring having a cross-sectional shape of an X-shape and a so-called X-ring can be used.

[0034]

Since the wheel drive bearing unit of the present invention is constructed and operates as described above, the coupling between the wheel support bearing unit and the constant velocity joint is performed by the retaining ring, so that the size and weight can be reduced. With the structure, the strength of the spline shaft can be sufficiently secured while sealing the spline engagement portion.
Further, since the axial dimension of the seal structure for closing the gap on the inner end side of the spline engagement portion can be reduced, the turning radius of the wheel during steering can be reduced, and the steering moment can be reduced.

[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 of a main part showing the third example.

FIG. 4 is a sectional view showing a first example of a conventional structure.

FIG. 5 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 Outer ring 4, 4a Hub 5 Inner ring 6 Rolling element 7 First flange 8 Knuckle 9 Outer ring track 10 Second flange 11 First inner ring track 12 Small-diameter stepped portion 13 Second inner raceway 14 Spline hole 15 Outer race for constant velocity joint 16 Inner race for constant velocity joint 17, 17a Spline shaft 18, 18a, 18b Drive shaft member 19 Outer engagement groove 20 Second spline hole 21 Inner engagement 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 part 31 Lock part 32 Lock groove 33 Retaining ring 34 Elastic ring 35 Caulking part 36 circular hole portion 37 locking step portion 38 cap 39 O-ring 40, 40a locking groove 41 inclined surface portion 42 flat surface 43 washer 44 minute gap 45 convex curved portion 46 cylindrical surface portion

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 are provided between each of the two inner raceways so as to freely roll, and a spline shaft engaging with the spline hole is provided in the outer half, and the inner half forms a constant velocity joint. A drive shaft member as an outer ring for a constant velocity joint, an inner diameter side engaging portion provided on an outer peripheral surface of an outer end portion of the spline shaft, and an inner peripheral surface of the hub opposed to the inner diameter side engaging portion. A wheel drive bearing unit comprising: a retaining ring that spans between an outer diameter side engaging portion provided at a portion thereof and that prevents the spline shaft from falling out of the spline hole. The above spline hole was formed on the inner peripheral surface of A portion inclined between the inner end of the hub and the inner end of the spline shaft in a direction in which the inner diameter increases toward the inner end of the hub; The seal ring is locked in a locking groove formed over the entire circumference in a portion facing the inclined portion, and the seal ring is elastically connected between the inner surface of the locking groove and the inclined portion. A bearing unit for driving a wheel, wherein a gap existing between the drive shaft member and the hub is closed by compression.