JP2002120506A - Bearing unit for driving wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate assembling work in a small and light structure, to prevent occurrence of tooth hummer sound harsh on the ear for a long time, and to suppress occurrence of axial backlash without severely regulating shape size accuracy. SOLUTION: Width of a male spline tooth disposed on the outer peripheral surface of a spline shaft 17 is increased with going inward in the axial direction. Width of a female spline tooth disposed on the inner peripheral surface of a spline hole 14 is decreased with going inward in the axial direction. As the spline shaft 17 is inserted into the spline hole 14, the male and female spline parts 38a and 39a are engaged with each other in the edge shape. A bolt 59 screwed with the tip of the spline shaft 17 through a cap 45 pulls the spline shaft 17 outwardly.

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 wheel support bearing unit are integrated, and a drive wheel ｛FF vehicle (front type) supported by an independent suspension type suspension. Engine with front-wheel drive)
Of the front wheels, rear wheels of FR vehicles (rear-wheel drive vehicle with front engine) and RR vehicles (rear-wheel drive vehicle of rear engine), and all wheels of 4WD vehicle (four-wheel drive vehicle) can be freely rotated with respect to the suspension system. And used to rotationally drive the drive wheels. That is, in order to support the drive wheels on the independent suspension type suspension and to rotationally drive the drive wheels, a wheel supporting bearing unit, a differential constant velocity joint and a wheel constant velocity joint at both ends of the drive shaft, respectively. A drive unit for a wheel is used in combination with a constant velocity joint unit to which the above-mentioned is coupled. The wheel drive bearing unit to which the present invention is applied is a combination of a wheel support bearing unit and a wheel side constant velocity joint which constitute such a wheel drive unit.

[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. 8 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] The above-mentioned wheel supporting bearing unit 1 includes an outer ring 3.
A hub 4 and an inner ring 5 are provided on the inner diameter side of a plurality of rolling elements 6, 6.
It is rotatably supported via a. Outer ring 3 of these
Is a knuckle 8 (see FIG. 9 to be described later) which forms a suspension device by an outward flange-shaped mounting portion 7 provided on the outer peripheral surface thereof.
It does not rotate when used while it is connected and fixed. It is to be noted that a structure in which the outer peripheral surface of the outer ring 3 is a simple cylindrical surface (without forming the mounting portion 7) and the outer ring 3 is internally fitted and fixed in a support hole of the knuckle 8 is also conventionally known. In addition, the outer ring 3
Are provided on the inner peripheral surface thereof, and the hub 4 and the inner ring 5 are rotatably supported concentrically with the outer ring 3 on the inner diameter side of the outer ring 3.

[0004] Of these, the hub 4 is located outside the outer peripheral surface (in the axial direction, the outer side in the width direction of the vehicle when assembled to the vehicle. The same applies throughout the present specification. The left side of each drawing except FIGS. 12 and 15). ) Flange 10 for supporting the wheel at the end portion
Is provided. Further, a first inner raceway 11 is formed at an intermediate portion of the outer peripheral surface of the hub 4, and the inner raceway 11 is also formed in the same direction (in the axial direction, the center of the vehicle in the width direction of the vehicle when assembled to the vehicle. The same applies throughout the specification). (The right side of each figure except FIGS. 12 and 15.)
The inner ring 5 having a second inner ring track 13 formed on the outer peripheral surface thereof is externally fitted and fixed to the small-diameter step portion 12 formed near the end. A spline hole 14 is provided at the center of the hub 4.
Is provided.

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

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

Further, when assembled to the suspension system of the automobile, the male spline portion 27 provided at the outer end of the drive shaft 26 is inserted into the second spline hole 20 provided at the center of the inner ring 16 for the constant velocity joint. Are spline-engaged. Then, a retaining ring 29 locked in a locking groove 28 formed over the entire outer peripheral surface of the outer end portion of the male spline portion 27 is formed at the outer peripheral edge of the outer end opening of the second spline hole 20. The male spline portion 27 is prevented from falling out of the second spline hole 20 by engaging with the locking step portion 30.

Although the drawing does not show a differential constant velocity joint provided at the output portion of the differential gear, the inner end of the drive shaft 26 is a tripod type constant velocity joint which is the differential constant velocity joint. Connect to the output of the joint. The tripod-type constant velocity joint, the drive shaft 26, and the constant velocity joint 2 constitute the constant velocity joint unit described above. In a state before being assembled to an automobile, the constant velocity joint unit and the wheel supporting bearing unit 1 are combined to form the above-described wheel drive unit.

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

An inner ring 5 having a second inner raceway 13 formed on the outer peripheral surface thereof is fitted around the inner end portion of the hub 4, and the inner end surface of the inner race 5 is formed at the inner end of the hub 4. A retaining ring 37 is retained in a retaining groove 36 formed over the entire outer circumference of a portion protruding inward in the axial direction. The retaining ring 37 suppresses the inner end surface of the inner ring 5 to prevent the inner ring 5 from shifting in the axial direction.

According to the second example of the conventional structure described in the above-mentioned US Pat. No. 4,881,842, the work of connecting the wheel supporting bearing unit 1a and the constant velocity joint 2a can be easily performed. That is, in the case of the first example of the conventional structure shown in FIG. 8, the nut 25 is screwed into the male screw portion 24 of the spline shaft 17 in order to connect the wheel supporting bearing unit 1 and the constant velocity joint 2. In addition, further tightening and laborious work are required. As described above, when the operation of connecting the wheel supporting bearing unit 1 and the constant velocity joint 2 is troublesome,
The cost required for assembling the wheel drive bearing unit is increased. In addition, the provision of the male screw portion 24 and the nut 25 increases the size and weight of the wheel drive bearing unit. On the other hand, in the case of the second example of the conventional structure described above, the wheel supporting bearing unit 1a and the constant velocity joint 2a
In order to combine the two, it is only necessary to bridge the retaining ring 33 between the inner peripheral surface of the outer end of the hub 4 and the outer peripheral surface of the outer end of the spline shaft 17. For this reason, in the case of the second example of the conventional structure, the work of connecting the wheel supporting bearing unit 1a and the constant velocity joint 2a can be easily performed, so that the cost required for assembly can be reduced, and the size and weight can be reduced. Can be achieved.

However, in any of the above-described conventional structures, a spline composed of a male spline portion 38 formed on the outer peripheral surface of the spline shaft 17 and a female spline portion 39 formed on the inner peripheral surface of the spline hole 14 is used. There is a possibility that a minute gap may be generated between the circumferentially opposed side surfaces of the teeth of the engaging portion 40 in a neutral state (a state in which torque is not transmitted between the spline shaft 17 and the hub 4). Although torque is transmitted between the spline shaft 17 and the hub 4 via the spline engagement portion 40, as described above, a minute gap is formed between the side surfaces of the teeth of the male and female spline portions 38 and 39. When a gap is generated, the male and female spline portions 38 and 39 relatively displace relative to each other in the circumferential direction even when the vehicle is accelerated or decelerated. Then, based on the relative displacement, the side surfaces of the teeth of the two spline portions 38 and 39 strongly contact each other, so that an occupant of the automobile may generate an unpleasant rattling sound.

Therefore, when implementing the first example of the conventional structure shown in FIG. 8 described above, for example, each tooth of the male spline portion 38 is moved with respect to the center axis of the spline shaft 17 (for example, 10 teeth).
It is considered to form a shape having a twist angle so as to incline. In this case, the female spline section 39 is spline-engaged with the male spline section 38.
Are formed in parallel with the central axis of the spline hole 14. The male spline portion 38 is formed by rolling the outer peripheral surface of the spline shaft 17 into a predetermined shape having a twist angle as described above, and then performing an induction hardening process. Cure the surface. On the other hand, the female spline portion 39 is formed in a predetermined shape by performing broaching on the inner peripheral surface of the spline hole 14 and is left in an unquenched state.

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

However, when the male spline portion 38 is formed in a shape having a twist angle in order to prevent the occurrence of the rattling noise, the press-in force increases due to the subtle change in the twist angle. fluctuate. For this reason, if the shape of the male spline portion 38 varies, the press-fit may still be excessive. For this reason, it is necessary to secure a certain degree of shape and dimensional accuracy, and it is difficult to sufficiently reduce costs. In the case of the first example of the conventional structure shown in FIG. 8 described above, even if the press input is excessive, if the nut 25 is strongly tightened to the male screw portion 24, the nut 25 By generating an axial force (axial force), a required press input can be obtained. However, as in the second example of the conventional structure shown in FIG. 9, the connection between the wheel supporting bearing unit 1a and the constant velocity joint 2a is stopped to facilitate the assembly of the wheel driving bearing unit. When using the ring 33, the axial force cannot be generated by the retaining ring 33.

When the male spline portion 38 is formed in a shape having a twist angle as described above, each tooth of the male spline portion 38 and each tooth of the female spline portion 39 are aligned in the axial direction. Since only both ends press against each other, there is a possibility that the contact surface pressure acting on the side surface of each tooth becomes excessive. When the contact surface pressure becomes excessive, there is a possibility that a part of each tooth is worn or plastically deformed relatively early. For this reason, each of the male and female spline sections 3
It is difficult to sufficiently secure the durability of the gears 8 and 39, and it is difficult to prevent the occurrence of the rattling noise for a long period of time.

[0017]

[Description of Prior Invention] In view of such circumstances, Japanese Patent Application 2000
228946 and 2000-258327,
Along with downsizing, weight reduction and ease of assembly work,
Regardless of the variation in the shape accuracy of each spline,
There is disclosed an invention for realizing a wheel drive bearing unit which can prevent the generation of rattling noise for a long period of time and which can sufficiently secure the durability of each spline portion. First, the present invention will be described with reference to FIGS.

It should be noted that the feature of the prior invention is that a spline engaging portion in which the spline shaft 17 and the spline hole 14 are engaged with each other while facilitating the connection work between the wheel supporting bearing unit 1b and the constant velocity joint 2b. The hub 4a and the spline shaft 17 are provided to prevent the rattling noise of the spline shaft 40a from being generated for a long period of time and to improve the durability of the male and female spline teeth 49, 51 constituting the spline engagement portion 40a. And the structure of the spline engagement portion 40a. Since the configuration and operation of the other parts are almost the same as those of the conventional structure shown in FIGS.
Equivalent portions are denoted by the same reference numerals, and redundant description is omitted or simplified.

In the illustrated example, the inner ring 5 having a second inner raceway 13 formed on the outer peripheral surface thereof is formed on a small-diameter stepped portion 12 formed near the inner end of the hub 4a constituting the wheel supporting bearing unit 1b. It is fitted outside. In order to prevent the inner ring 5 from coming out of the small-diameter step portion 12, a caulking portion 42 is formed at the inner end of the hub 4a. That is, after the inner ring 5 is externally fitted to the small-diameter step portion 12, the hub 4
a portion protruding from the inner end surface of the inner ring 5 at the inner end portion a is plastically deformed radially outward to form the caulked portion 42;
The inner end surface of the inner ring 5 is suppressed by the caulking portion 42.

An engaging groove 43 is formed on the outer peripheral surface of the outer end of the spline shaft 17 constituting the drive shaft member 18b over the entire circumference. When the spline shaft 17 is inserted into the spline hole 14 provided in the center of the hub 4a, the outer half of the retaining ring 33 whose inner half is locked in the locking groove 43, The spline shaft 17 is axially rattled in the spline hole 14 in contact with or near the locking step portion 44 formed near the outer end of the inner peripheral surface of the hub 4a. It is prevented from falling out of the spline hole 14. A portion of the center hole of the hub 4a closer to the outer end opening than the locking step portion 44 does not form the female spline portion 39a, and has an inner diameter equal to or larger than the diameter of the root circle of the female spline portion 39a. It is simply a cylindrical surface.

The retaining ring 33 is connected to the spline shaft 17.
Prior to insertion into the spline hole 14, it is mounted in the locking groove 43. When inserting the spline shaft 17 into the spline hole 14,
The above-mentioned spline hole 1 is elastically reduced in diameter.
Pass through 4. When the retaining ring 33 is aligned with the locking step 44, the diameter of the retaining ring 33 is elastically restored, and the retaining ring 33 is connected to the locking step 44 and the locking groove as described above. 43 and can be freely bridged. The positions of the locking step portions 44 and the locking grooves 43 correspond to the male spline teeth 49, 49 constituting the male spline portion 38 a formed on the outer peripheral surface of the spline shaft 17, and the spline hole 1.
The female spline section 39a formed on the inner peripheral surface of the female spline 4 is formed in accordance with the shape of the female spline teeth 51, 51. Therefore, in a state where the retaining ring 33 is elastically restored, the retaining ring 33 is hung between the locking step portion 44 and the locking groove 43 without rattling, or is temporarily rattled. However, even if they are present, the amount is small. In the case of the illustrated example, as shown in detail in FIG. 16, the locking step portion 44 is arranged so as to move toward the outer diameter side (the upper side in FIG. 16) in the axially outward direction, and to the center axis of the hub 4 a. It is inclined by an angle α with respect to a virtual plane existing at right angles to the direction.

The opening at the outer end of the center hole of the hub 4a is closed by a cap 45. On the other hand, the outer race 15 for the constant velocity joint constituting the drive shaft member 18b
A seal ring 47 is externally fitted on the outer peripheral surface of the shoulder portion 46 formed at the base end of the base. And this seal ring 47
Are brought into contact with the inner surface of the caulking portion 42, and the caulking portion 42 and the outer race 15 for a constant velocity joint are brought into contact with each other.
Is closing the gap between them. In the illustrated example, as a preferable structure, a portion of the inner surface of the caulking portion 42 where the leading edge of the seal lip abuts is a flat surface existing in a direction perpendicular to the central axis, and the seal lip is It comes into contact with the side surface in a stable state. As described above, the cap 45 and the seal ring 47
A spline engaging portion 40a comprising a male spline portion 38a formed on the outer peripheral surface of the spline shaft 17 and a female spline portion 39a formed on the inner peripheral surface of the spline hole 14.
In addition, the spline engagement portion 40a is prevented from getting rusted by preventing foreign matter such as rainwater from entering.

Further, in the case of the wheel drive bearing unit of the prior invention, each male spline tooth 49 constituting the male spline portion 38a formed on the outer peripheral surface of the spline shaft 17 is provided.
The width of 49 (FIGS. 11 and 12) gradually increases toward the inside in the axial direction over substantially the entire length except for the incomplete portion 48 provided at the end of each of the male spline teeth 49 and 49. Has been changed. Therefore, the groove 52 existing between the male spline teeth 49 adjacent to each other in the circumferential direction,
The width in the circumferential direction of 52 gradually narrows toward the inner end side. For this reason, both sides in the circumferential direction of the male spline teeth 49, 49 existing at the axially intermediate portion of the male spline portion 38a are inclined in the opposite directions by the same angle with respect to the axial direction.

The axial end portions of the male spline portion 38a are arranged such that the height in the diametrical direction of each male spline tooth 49, 49 becomes gradually smaller toward both axial ends.
The incomplete portion 48 is inclined at a relatively large angle. In FIG. 11, the width of each male spline tooth 49, 49 appears to increase sharply at the incomplete portion 48. This is because each male spline tooth 49 has a substantially trapezoidal cross section. This is because the height in the diametrical direction of 49, 49 decreases rapidly toward both ends in the axial direction. As can be seen from this, in the present specification, the change in the width of each male spline tooth 49, 49 means that each male spline tooth 49 has the same height in the diametric direction (for example, at the tip of each tooth). , 49 change.

On the other hand, the width of each of the female spline teeth 51, 51 (FIGS. 14 and 15) constituting the female spline portion 39a formed on the inner peripheral surface of the spline hole 14 is set at the end of each of the female spline teeth 51, 51. Except for the incomplete portion 50 provided in the portion, the width is changed so as to gradually decrease toward the inside in the axial direction over substantially the entire length. Therefore, the widths of the grooves 53, 53 that constitute the female spline portion 39a and are present between the circumferentially adjacent female spline teeth 51, 51 gradually increase toward the inner end side. In this manner, the male spline portion 38a and the female spline portion 39a differ in the directions in which the widths of the male and female spline teeth 49, 51 and the grooves 52, 53 of the spline portions 38a, 39a increase in the axial direction. I have. Further, each female spline tooth 51 constituting the female spline portion 39a,
Both sides in the circumferential direction of 51 are inclined with respect to the axial direction by the same angle as in the case of the male spline teeth 49 constituting the male spline portion 38a.

The male and female spline teeth 49, 51
The inclination angle of the both side surfaces with respect to the axial direction is 0.75 in consideration of the positioning accuracy of the spline shaft 17 and the spline hole 14 in the axial direction and the workability of the male and female spline teeth 49 and 51. About 1.25 degrees (a taper angle of 1.5 to 2.5 degrees, which is an angle formed between both side faces of the male and female spline teeth 49, 51). In addition, the axial length of the spline shaft 17 and the spline hole 14 is set to ensure the durability and the male and female spline teeth 49, 51.
In consideration of the workability of the above, the thickness is about 20 to 35 mm. Accordingly, the module of the spline shaft 17 and the spline hole 14 is set to about 1.25 to 1.75, and the tooth thicknesses of the male and female spline teeth 49 and 51 are extremely different at both axial ends. (The ratio of the widths at both ends in the axial direction is suppressed to 2.0 or less).

The operation of connecting the constant velocity joint 2b having the spline shaft 17 and the wheel supporting bearing unit 1b incorporating the hub 4a having the spline hole 14 is performed as follows. First, the spline shaft 17 is inserted into the spline hole 14 while the male spline portion 38a and the female spline portion 39a are spline-engaged. Then, the male and female splines 38a, 39a are pushed in until they are engaged in a wedge shape. In this state, these male and female spline sections 3
The circumferentially opposed side surfaces of the male and female spline teeth 49, 51 of 8a, 39a substantially uniformly contact each other over the entire axial length of the male and female spline portions 38a, 39a.

In this state, as shown in FIG. 16, the outer peripheral half side surface of the retaining ring 33 locked in the locking groove 43 provided in the outer end of the spline shaft 17 has the spline hole 17 as shown in FIG. 1
4 comes into contact with the slope of the locking step 44 provided on the inner peripheral surface of the outer end. Therefore, in this state, the retaining ring 33 locked in the locking groove 43 is engaged with the locking step 44 formed on the inner peripheral surface of the spline hole 14, and the spline shaft 17 is connected to the spline hole 14. From being displaced in the direction of coming out of the vehicle. When the retaining ring 33 is aligned with the locking step 44, its diameter is elastically restored. At this time, the outer diameter of the retaining ring 33 becomes (Inner peripheral surface of the cylindrical surface portion outside the locking step portion 44)
If the dimensional tolerance of each part can be regulated so as not to cause the above, the backlash in the axial direction of the spline engagement 40a can be eliminated.

According to the wheel drive bearing unit of the prior invention constructed as described above, since the connection between the wheel support bearing unit 1b and the constant velocity joint 2b is performed by the retaining ring 33, the above-described configuration is shown in FIG. As in the case of the second example of the conventional structure, the assembling work can be facilitated, and the size and weight can be reduced. Further, in the case of the prior invention, the spline shaft 1
7, a spline engaging portion 40a composed of a male spline portion 38a provided on the outer peripheral surface and a female spline portion 39a provided on the inner peripheral surface of the spline hole 14 can prevent rattling noise. That is, in the case of the prior invention, the widths of the male and female spline teeth 49, 51 constituting the male spline portion 38a and the female spline portion 39a are changed so as to gradually increase in directions different from each other with respect to the axial direction. ing. Then, the male and female spline portions 38a, 39a are
By fitting in a state where there is no rattling, or in a state where there is only a little rattling (a state where there is a slight gap), it is possible to prevent the above rattling noise from being generated when the automobile is running.

Further, according to the above-mentioned invention, the male and female spline teeth 49 of the male and female spline portions 38a and 39a,
The side surfaces of the splines 51 can be brought into contact with each other by a substantially uniform contact surface pressure over the entire length in the axial direction, and the maximum contact surface pressure acting on the side surfaces of the male and female spline teeth 49 and 51 can be reduced. Therefore, in the case of the first invention, the male and female spline teeth 4 of the male and female spline portions 38a and 39a are used.
The durability of the gears 9 and 51 can be improved, and the generation of the rattle can be prevented for a long time.

[0031]

In the case of the wheel drive bearing unit according to the prior invention, male and female spline portions 38 are provided.
a, 39a in the axial direction, that is, the spline engagement portion 4
In order to prevent rattling of 0a, the dimensions and shape of each part must be processed with high precision. The reason for this is that, in a state where the wheel supporting bearing unit 1b and the constant velocity joint 2b are connected to each other, the retaining ring 33 locked in the locking groove 43 on the constant velocity joint 2b side as shown in FIG. This is because it is difficult to abut the radially intermediate portion of the locking step 44 formed on the bearing unit 1b side.

That is, as described above, the locking step 44 is inclined by an angle α with respect to a virtual plane existing at right angles to the center axis of the hub 4a. The male and female spline teeth 4 of the male and female spline portions 38a and 39a
In a state where the side surfaces of the surfaces 9 and 51 are in close contact with each other,
As shown in FIG. 16, if the retaining ring 33 bites between the locking step 44 and the inner surface of the locking groove 43 in a wedge shape, the occurrence of the axial displacement is prevented. it can. That is, in order to securely connect the wheel supporting bearing unit 1b and the constant velocity joint 2b by the retaining ring 33, as shown by a chain line in FIG. It is necessary to securely contact not only the inner peripheral edge of the locking step portion 44 but also a portion that is slightly outward from the inner peripheral edge. What happens is the retaining ring 33
Does not come into contact with the locking step portion 44 but comes into contact with the edge of the inner peripheral edge of the locking step portion 44, the direction of the load vector acting on the retaining ring 33 from the contact portion. But,
Different from the normal contact state, the load component toward the radially inward direction for reducing the diameter of the retaining ring 33 increases. Due to this load component, the retaining ring 33 may be reduced in diameter and enter the bottom of the locking groove 43, and the spline shaft 17 may fall out of the spline hole 14. On the other hand, as shown by a solid line in FIG. 17, the axial displacement of the retaining ring 33 is made in a state where the outer peripheral edge of the retaining ring 33 is in contact with the inner peripheral surface of the cylindrical surface portion 54 located outside the spline hole 14. In this state, it is necessary for the surface of the retaining ring 33 to abut both the locking step 44 and the inner surface of the locking groove 43 in this state. Therefore, each of the male and female spline teeth 4
The hub 4a in a state where the side surfaces of the hubs 9 and 51 are in close contact with each other.
The permissible value of the error of the positional relationship between the shaft and the spline shaft 17 in the axial direction is only ΔL shown in FIG.

Regardless of the dimensional error and shape error of each component,
In order to perform reliably bite wedge of the stop ring 33, in order to increase the △ L, increase the width W ₄₄ in the radial direction of the engaging step portion 44, to increase the inclination angle α There is a need. Possible to increase the width W ₄₄ of this is the thickness of the hub 4a is limited,
In addition, it is difficult to secure sufficient strength.
It is also difficult to increase the inclination angle α for the following reasons.

That is, it is necessary to regulate the inclination angle α so that the diameter of the retaining ring 33 does not shrink even when a strong force is applied in a direction in which the spline shaft 17 is pulled out from the spline hole 14. That is, this retaining ring 33
A force is received from each of the locking groove 43 and the locking step portion 44. When the two forces are balanced, the diameter of the retaining ring 33 does not decrease. In this case, if the force in the direction in which the spline shaft 17 is pulled out from the spline hole 14 is F, the force acting on the retaining ring 33 from the locking step 44 is F / cos (α / 2), Of these, the component perpendicular to the slope of the locking step 44 is F, and the component parallel to this slope is {F / cos (α / 2)} · sin (α / 2) = F
Tan (α / 2). On the other hand, if the friction coefficient acting on the contact portion between the slope of the locking step portion 44 and the retaining ring 33 is μ, the frictional force acting on this contact portion is μF, so that the component parallel to the slope is Needs to be μF or less. Remove the equal sign for safety and Ftan (α / 2) <
μF is a condition for preventing the diameter of the retaining ring 33 from shrinking. By dividing both sides of this equation by F, tan (α / 2) <
μ, that is, α <2 tan ⁻¹ μ, is a condition under which the diameter of the retaining ring 33 does not shrink.

As described above, the effect of preventing the rattle of the spline engagement portion 40a increases as the inclination angle α increases. On the other hand, as the angle α increases, the diameter of the retaining ring 33 is more likely to be reduced.
Is disengaged from the locking step portion 44, and the spline shaft 17 easily comes out of the spline hole 14. Therefore, it is necessary to regulate the angle α in consideration of this. Usually, since the static friction coefficient μ between steels is about 0.18, when the inclination angle α when μ is set to 0.18 is obtained by the above equation, the inclination angle α is 20.4 degrees or less. Becomes Usually, the angle α is equal to the spline shaft 17.
Is determined by an experiment so that the pulling force becomes 3500 N or more, but a value of about 15 to 20 degrees is generally adopted.

As described above, in order to prevent rattling of the spline engagement portion 40a, the width W44 in the radial direction of the locking step portion ₄₄ is increased, and the inclination angle α is increased. Things are difficult. Therefore, another means is required to prevent the spline engagement portion 40a from rattling. The present invention has been made in view of such circumstances.

[0037]

A bearing unit for driving a wheel according to the present invention comprises an outer ring, a hub, a rolling element, a drive shaft member, and the like, as in the second example of the conventional structure shown in FIG. Is provided. The outer ring has a double-row outer ring raceway on the inner peripheral surface and does not rotate during use. Also, the hub has a flange for supporting the wheel at a portion near the outer end of the outer peripheral surface,
A first inner ring raceway is provided directly or via a separate inner ring at an intermediate portion of the outer peripheral surface, a spline hole having a female spline tooth formed on the inner peripheral surface is provided at the center, and a second inner ring is formed on the outer peripheral surface. The inner race having the raceway is externally fitted and fixed to a portion of the outer peripheral surface near the inner end. In addition, a plurality of rolling elements are provided between the outer raceways and the first and second inner raceways so as to be capable of rolling in plurals. The drive shaft member is
A spline shaft formed on the outer peripheral surface with male spline teeth engaging with the female spline teeth is provided at the outer end, and the inner end is an outer ring for a constant velocity joint that constitutes a constant velocity joint.

In particular, in the wheel drive bearing unit according to the present invention, similarly to the wheel drive bearing unit according to the preceding invention, the female spline teeth and the male spline teeth are connected to the spline shaft. The shape is such that there is no backlash in the circumferential direction with insertion from the inner end opening into the spline hole. Further, in the case of the wheel drive bearing unit of the present invention, a closing member which covers the outer end opening of the spline hole by being attached to the outer end of the hub, and a locking member provided on the outer end surface of the spline shaft. The hole is connected. Then, a force that increases the insertion depth into the spline hole is applied to the spline shaft by a member that couples the closing member and the locking hole.

[0039]

According to the wheel drive bearing unit of the present invention configured as described above, the size and weight can be reduced, and the assembling work can be facilitated, as in the case of the wheel drive bearing unit according to the preceding invention. At the same time, it is possible to prevent generation of rattling noise at a spline engagement portion between a male spline portion provided on the outer peripheral surface of the spline shaft and a female spline portion provided on the inner peripheral surface of the spline hole. That is, according to the present invention, since the connection between the hub and the spline shaft is performed by the retaining ring, the assembling work can be facilitated. Further, in the case of the present invention, if necessary, the side surfaces of the teeth of the male and female splines can be brought into contact with substantially uniform surface pressure in the axial direction. The maximum contact surface pressure acting on the side surface of can be reduced. Therefore, the generation of the rattle can be prevented for a long period of time, and the durability of each tooth of the male and female splines can be sufficiently ensured.

Further, in the case of the wheel drive bearing unit of the present invention, a force for increasing the insertion depth into the spline hole is applied to the spline shaft by a member connecting the closing member and the locking hole. , The rattling of the spline engagement portion can be prevented even if the dimensions and shape of each portion are not processed with high precision.

[0041]

1 and 2 show a first embodiment of the present invention corresponding to claims 1, 2, and 4. FIG.
It should be noted that the feature of the present invention is that a force (elasticity) directed outward with respect to the spline shaft 17 in order to prevent rattling of the spline engaging portion 40a without processing the dimensions and shape of each part with high precision.
In the structure of the part to which is given. The structure and operation of the other parts are the same as those of the previous invention shown in FIGS. 10 to 15 described above. Therefore, the description of the equivalent parts will be omitted or simplified, and the following description will focus on the characteristic parts of the present invention. .

Also in the case of this example, the male spline teeth 49, 49
Are tapered spline teeth whose width in the circumferential direction increases toward the inner end side, as shown in FIGS.
As shown in the figure, the width in the circumferential direction is increased toward the outer end side. The male spline portion 38a and the female spline portion 39a are designed to engage with each other in the circumferential direction as the spline shaft 17 is inserted into the spline hole 14 from the inner end opening.

A cap 45 as a closing member is attached to a cylindrical surface portion 54 formed at a portion located outside the female spline portion 39a at the outer end of the spline hole 14. Thus, the outer end opening of the spline hole 14 is closed. The cap 45 is formed in a round bowl shape by plastically deforming an elastic metal plate such as a stainless steel plate. The cap 45 is formed on a bottomed cylindrical main body 55 and an outer peripheral edge of the main body 55. And an outward flange-shaped flange portion 56. Such a cap 45 is formed by connecting the cylindrical portion 61 constituting the peripheral portion of the main body portion 55 to the cylindrical surface portion 5.
4, the inner fitting is fixed by interference fitting. Further, a circular through hole 57 is formed at the center of the bottom plate portion 62 constituting the main body portion 55. Further, a screw hole 58 is formed in the center of the outer end surface of the spline shaft 17.

When the wheel supporting bearing unit 1b and the constant velocity joint 2b are combined to form a wheel driving bearing unit, the screw portion 60 of the bolt 59 inserted into the through hole 57 is inserted into the screw hole 58. Screw together and tighten further. The head 63 of the bolt 59 contacts the peripheral portion of the through-hole 57 on the outer surface of the bottom plate 62. And this bottom plate part 6
2 is pressed by the head 63 and elastically deforms in a direction in which a central portion thereof is displaced inward (in a direction in which an outer surface becomes a mortar shaped concave surface). As a result, outward elasticity is applied to the bolt 59. And the spline shaft 17 is
The bolt 59 pulls outward, that is, a state in which elasticity in a direction of increasing the insertion depth into the spline hole 14 is applied. Further, in this state, the bolt 59 remains in a state in which the thrust load based on the elastic deformation of the cap 45 is applied, so that the bolt 59 is not accidentally loosened.

As described above, in the case of the wheel drive bearing unit of the present invention, the cap 45 by the bolt 59 is used.
Because the elasticity of the spline shaft 17 in the direction of increasing the insertion depth into the spline hole is imparted to the spline shaft 17 based on the elastic deformation of the male member, the male and female members need not be machined with high precision. Spline 38a and female spline 39a
The rattling of the spline engagement portion 40a can be prevented.
That is, due to the processing error of the size and shape of each part (a size exceeding ΔL described above), each of the male and female spline parts 38
a, 39a, male and female spline teeth 49, 51
In a state in which the side surfaces are in close contact with each other, there is a possibility that the retaining ring 33 is separated from the locking step portion 44 as shown in FIG. In the case of the present invention, even in such a state, the outward elasticity is applied to the spline shaft 17 to the hub 4a, so that the rattling can be prevented.
Also, if the cap 45 is damaged or the bolt 5
Even if the outer ring 9 is loosened and the outward elasticity applied to the spline shaft 17 is lost, the retaining ring 33 is removed.
Comes into contact with the locking step 44, and the spline shaft 17
Is prevented from coming out of the spline hole 14.

Next, FIG. 3 also shows a second example of the embodiment of the present invention corresponding to claims 1, 2, and 4. In the case of this example, the main body 55 of the cap 45 is fitted inside the cylindrical surface 54 formed at the outer end of the spline hole 14 by a clearance fit. For this reason, a chamfered portion 64 is formed at the outer peripheral edge of the outer end of the spline hole 14, and an O-ring 65 is sandwiched between the chamfered portion 64 and the cap 45 so that a gap between the cap 45 and the hub 4a is formed. Is sealed. Other configurations and operations are the same as those of the above-described first example.

The first to third embodiments shown in FIGS.
In two examples, the inner end face of the head 63 of the bolt 59 and the cap 4
5 is configured to prevent foreign matter from penetrating into the spline engaging portion 40a from the through hole 57 of the cap 45 at the contact portion with the outer end surface. An annular groove is formed on the inner end surface of the head 63 of the bolt 59,
It is also possible to attach a sealing member such as an O-ring to this annular groove.

Next, FIGS. 4 and 5 show a third embodiment of the present invention corresponding to the first, third and fourth aspects. In the case of this example, a locking hole 66 having a stepped inner peripheral surface is formed at the center of the outer end surface of the spline shaft 17. The locking hole 66 is a stepped hole in which the inner diameter of the back is larger than the inner diameter of the opening, and has a step 67 facing the back in the middle of the inner peripheral surface. Then, a coupling hook 69 is hooked between such a locking hole 66 and a hub cap 68 as a closing member, which is attached to the outer end of the hub 4a. And the locking hole 66.

The connecting hook 69 is made of polyamide 66,
It is integrally formed of an elastic material such as a synthetic resin such as polyacetal. First and second elastic locking portions 71 and 72 are provided at both ends of a cylindrical connecting rod portion 70. These two elastic locking portions 71 and 72 are respectively conical (umbrella-shaped).
The apex angle θ in the free state shown in FIG.
Are about 60 degrees, respectively, but in a state of being bridged between the locking hole 66 and the hub cap 68, each apex angle is elastically widened as shown in FIG. Although the first elastic locking portion 71 has a smaller diameter than the second elastic locking portion 72, the outer diameter of the first elastic locking portion 71 in the free state is equal to the diameter of the locking hole 66. Slightly larger than the inside diameter of the opening.

The work of bridging the connecting hook 69 between the locking hole 66 and the hub cap 68 is performed as follows. The hub cap 68 is previously attached to the outer end of the hub 4a by interference fit or clearance fit. The through hole 5 formed in the center of the hub cap 68
7, the coupling hook 69 is pushed in with the first elastic locking portion 71 having a relatively small diameter first. By this pushing operation, the first elastic locking portion 71 passes through the through hole 57 while being elastically deformed in a direction to reduce the outer diameter, and is further pushed into the locking hole 66. Then, the first elastic locking portion 71 passes through the opening of the locking hole 66 while being elastically deformed in a direction of reducing the outer diameter, and is elastically restored in a direction of expanding the outer diameter after passing.

As a result, the outer peripheral edge of the first elastic locking portion 71 engages with the step 67 formed at the intermediate portion of the inner peripheral surface of the locking hole 66, and the first elastic locking portion 71 is engaged. The stopper 71 does not come out of the locking hole 66. In the process of pushing the first elastic locking portion 71 into the locking hole 66 in this manner,
The outer peripheral edge of the second elastic locking portion 72 abuts against the outer surface of the hub cap 68, and the second elastic locking portion 7
2 spreads elastically. The spline shaft 17 provided with the locking hole 66 based on the elastic deformation of the first and second elastic locking portions 71 and 72 and the hub cap 68.
To the outside. Based on this elasticity, rattling of the spline engagement portion 40a is prevented. Further, since the outer peripheral edge of the second elastic locking portion 72 elastically abuts on the outer surface of the hub cap 68 over the entire circumference, the through hole 57 is sealed. Other configurations and operations are the same as those in the first and second examples.

Next, FIG. 6 shows a fourth embodiment of the present invention corresponding to claims 1, 3 and 4. In this example, the cap 68a and the coupling hook 69a are formed as an integral structure. Also, an O-ring 73 is attached to a fitting portion of the cap 68a with the hub 4a to seal the fitting portion. Further, the structure is such that the retaining ring bridged between the hub 4a and the spline shaft 17 is omitted, and the structure is inexpensive.

In each of the above examples, the case has been described in which the male spline teeth 49, 49 and the female spline teeth 51, 51 are all tapered spline teeth. In addition, the female spline teeth may have any shape as long as the spline shaft is inserted into the spline hole from the inner end opening so as to eliminate rattling in the circumferential direction. For example, FIG. 7 showing a shape corresponding to claim 5
As shown in the figure, the male spline teeth 49a, 49 constituting the male spline portion 38b provided on the outer peripheral surface of the spline shaft 17 are provided.
a may be a torsion spline formed in a direction inclined with respect to the direction of the center axis of the spline shaft 17. In this case, the female spline teeth constituting the female spline portion on the hub side are parallel splines formed in a direction coinciding with the direction of the center axis of the hub. The reason why the male spline teeth, not the female spline teeth, are torsion splines is that the spline teeth on the outer peripheral surface can be easily processed as torsion splines. Therefore, if there is no problem in processing, the male spline teeth can be parallel splines and the female spline teeth can be torsional splines.

[0054]

Since the present invention is constructed and operated as described above, it has a small and lightweight structure, can facilitate the assembly work, reduce the cost, and reduce the generation of harsh rattle. For a long time, and the durability can be improved. Also, since it is not necessary to make the processing accuracy of each part strict,
The cost reduction effect can be further improved.

[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 an enlarged view of a portion A in FIG.

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

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

FIG. 5 is a sectional view showing a connecting hook used in a third example in a free state.

FIG. 6 is a sectional view showing a fourth example of the embodiment of the present invention.

FIG. 7 is a view similar to FIG. 11, showing another shape of the male spline teeth.

FIG. 8 is a sectional view showing a first example of a conventional structure.

FIG. 9 is a sectional view showing the second example with a part thereof omitted;

FIG. 10 is a cross-sectional view showing one example of a structure according to the prior invention.

FIG. 11 is an enlarged view of a portion B in FIG. 10 showing details of a male spline portion.

FIG. 12 is a sectional view taken along line CC of FIG. 11;

FIG. 13 is a view showing the female spline portion provided at the center of the hub and viewed from the same direction as FIG. 10 with the drive shaft member removed.

FIG. 14 is an enlarged view of a portion D in FIG. 13 showing details of a female spline portion.

FIG. 15 is a sectional view taken along line EE of FIG. 14;

FIG. 16 is an enlarged view of a portion F in FIG. 10;

FIG. 17 is a view similar to FIG. 16, which is used to explain the reason why an error in the shape and size leads to rattling;

[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 Mounting part 8 Knuckle 9 Outer ring track 10 Flange 11 First inner ring track 12 Small diameter step 13 Second inner ring raceway 14 Spline hole 15 Outer ring for constant velocity joint 16 Inner ring for constant velocity joint 17 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 thread part 25 Nut 26 Drive shaft 27 Male spline part 28 Lock groove 29 Lock ring 30 Lock step part 31 Lock part 32 Lock groove 33 Stop ring 34 Elastic ring 35 Lock step 36 Lock groove 37 Retaining rings 38, 38a, 38b Male spline portions 39, 39a Female spline portions 40, 40a Spline engagement portions 4 Caulking part 43 Locking groove 44 Locking step part 45 Cap 46 Shoulder part 47 Seal ring 48 Incomplete part 49, 49a Male spline teeth 50 Incomplete part 51 Female spline teeth 52 Groove part 53 Groove part 54 Cylindrical surface part 55 Body part 56 Flange part 57 Through hole 58 Screw hole 59 Bolt 60 Screw part 61 Cylindrical part 62 Bottom plate part 63 Head 64 Chamfer part 65 0 Ring 66 Locking hole 67 Step part 68, 68a Hub cap 69, 69a Connecting hook 70 Connecting rod part 71 First Elastic locking portion 72 second elastic locking portion 73 O-ring

Claims (5)

[Claims] 1. A first inner ring raceway having a double row of outer raceways on an inner peripheral surface and not rotating even during use, and a flange for supporting wheels at a portion near the outer end of the outer peripheral surface. Alternatively, a spline hole having a female spline tooth formed on the inner peripheral surface is provided at the center portion at an intermediate portion of the outer peripheral surface via a separate inner ring, and an inner ring having a second inner raceway formed on the outer peripheral surface is provided at the outer periphery. A hub externally fitted and fixed to a portion near the inner end of the surface, a plurality of rolling elements provided so as to be able to freely roll between each of the outer raceways and the first and second inner raceways, A spline shaft having male spline teeth formed on an outer peripheral surface thereof for spline engagement with spline teeth is provided at an outer end portion, and a drive shaft member having an inner end portion as an outer ring for a constant velocity joint constituting a constant velocity joint is provided. In the wheel drive bearing unit, The in-tooth and the male spline teeth,
As the spline shaft is inserted into the spline hole from the inner end opening, the shape is such that there is no play in the circumferential direction, and the spline shaft is attached to the outer end of the hub and the outer end of the spline hole. The closing member closing the opening and the locking hole provided on the outer end surface of the spline shaft are connected to apply a force to the spline shaft in a direction to increase the insertion depth into the spline hole. Characteristic wheel drive bearing unit. 2. The locking hole is a screw hole, a bolt is provided as a connecting member for connecting the closing member and the locking hole, and the closing member is a hub cap made of elastic metal.
The hub cap is elastically deformed by screwing and tightening the screw portion of the bolt inserted through the through hole formed in the hub cap into the screw hole, and the elastic force based on this elastic deformation is applied to the spline hole of the spline shaft. The wheel drive bearing unit according to claim 1, wherein the force is a force in a direction to increase an insertion depth of the wheel drive. 3. An elastic hole made of an elastic material, wherein the locking hole is a stepped hole having a larger inner diameter in a deeper portion than an inner diameter of the opening, and is a connecting member for connecting the closing member and the locking hole. A coupling hook provided with first and second elastic locking portions is provided on the portion,
The closing member is a hub cap, and the first elastic locking portion inserted through the through hole formed in the hub cap is engaged with a step formed on the inner peripheral surface of the stepped hole to form the stepped portion. The second elastic locking portion is brought into contact with the outer surface of the hub cap in an elastically deformed state in a state where it is prevented from falling out of the hole, and the elastic force based on this elastic deformation is applied to the spline hole of the spline shaft. The wheel drive bearing unit according to claim 1, wherein the force is a force in a direction to increase an insertion depth into the wheel drive bearing unit. 4. The male spline teeth are tapered spline teeth whose width in the circumferential direction increases toward the inner end side, and the female spline teeth increase in width in the circumferential direction toward the outer end side. 2. A spline tooth.
4. The wheel drive bearing unit according to any one of claims 1 to 3. 5. The male spline teeth are torsion splines formed in a direction inclined with respect to the direction of the center axis of the spline shaft, and the female spline teeth are formed in a direction coinciding with the direction of the center axis of the spline hole. The wheel drive bearing unit according to any one of claims 1 to 3, which is a formed parallel spline.