JP2002283806A - Bearing device for drive axle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To positively prevent a disconformity of center line of a rotational axis of a uniform motion universal joint with the center of a king pin to boost driveability of an automobile. SOLUTION: A caulking member 37 is formed in radial direction by plastically deforming an end portion of a hub 30 radially-outwardly, and a hub flange 30 is caused to be united with an inner flange 40 fitted on a periphery of the hub flange 30. An outer joint member 72 of a uniform motion universal joint 70 is fitted into a bore of the hub flange 30 such that the outer joint member 72 can transfer torque and the caulking member 37 is caused to contact a shoulder portion 72d of the outer joint member 70 in the axial direction. A planar face 38 is formed on the caulking member 37 such that the variation of position of the planar face 38 in the axial direction falls within a standard value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device for rotatably supporting driving wheels of an automobile or the like (rear wheels of an FR vehicle, front wheels of an FF vehicle, all wheels of a 4WD vehicle) with respect to a vehicle body. It is.

[0002]

2. Description of the Related Art Various types of bearing devices for driving wheels of automobiles have been proposed according to their uses. For example, in the drive wheel bearing device shown in FIG. 5, the hub wheel 3 and the double row bearing 1 are unitized, and the outer joint member 7a of the constant velocity universal joint 7 is fitted to the inner periphery of the hub 3 so as to be able to transmit torque. Structure.

The bearing 1 has a double-row outer race 1a and inner races 2a and 2b, and a double-row rolling element 5 incorporated between the outer race 1a and the inner races 2a and 2b. In the illustrated bearing device, one of the double-row inner races 2b is formed directly on the outer periphery of the hub wheel 3,
The other 2 a is formed on the outer periphery of the inner ring 4 fitted to one end of the hub wheel 3. A nut 8 is provided at the shaft end of the outer joint member 7a.
Is screwed, and by tightening the nut 8, the back surface 4a of the inner race 4 is attached to the shoulder 7a of the outer joint member 7a.
1 and the inner ring 4 is positioned, and a predetermined amount of preload is applied inside the bearing.

By the way, in recent years, from the viewpoint of reducing the size of the bearing device in the axial direction and reducing its weight, the hub wheel 3 and the inner ring 4 are integrated by caulking, not by tightening the nut 8, and preload is applied inside the bearing. Proposed structures have been proposed. This is because, after the inner ring 4 is fitted to the outer periphery of the hub wheel 3, as shown in FIG. 6, one end of the hub wheel 3 protruding from the inner ring 4 is plastically deformed to the outer diameter side, and this caulking is performed. The positioning of the inner race 4 and the application of preload are performed by engaging the portion 3a with the back surface 4a of the inner race 4.

[0005]

Generally, in the driving wheels of an automobile, it is necessary that the center of the kingpin and the joint center O 'of the constant velocity universal joint 7 coincide with each other in order to secure the running stability of the vehicle. . However, when caulking the end of the hub wheel 3 as described above, it is inevitable that the end face of the caulked portion 3a varies in the axial direction, and therefore,
When the shoulder 7a1 of the outer joint member 7a is brought into contact with the end face of the caulked portion 3a, the position of the joint center O 'varies, making it difficult to match the kingpin center with the joint center O'.

Accordingly, an object of the present invention is to provide a drive wheel bearing device capable of reliably preventing a mismatch between a kingpin center and a joint center of a constant velocity universal joint.

[0007]

In order to achieve the above object,
In the present invention, an outer member having a double-row outer race on the inner periphery, and at least one of a double-row inner race facing the outer race of the outer member, a first inner member, and a double-row inner race are formed. An inner member that comprises a second inner member, and the first inner member and the second inner member are non-separably coupled at a radially caulked portion formed by plastically deforming the first inner member to the outer diameter side. A double-row rolling element interposed between the outer member and the inner member, wherein the outer joint member of the constant velocity universal joint is fitted to the inner periphery of the first inner member so as to be capable of transmitting torque, and a caulking portion In the drive wheel bearing device for contacting the outer joint member with the outer joint member in the axial direction, of the caulked portion, the contact portion with the outer joint member is made a flat surface, and the variation in the axial position of this flat surface is within a standard value. Regulated.

[0008] In the caulking portion, by making the contact portion with the outer joint member a flat surface, the crimping portion and the outer joint member come into surface contact via the flat surface. The contact surface pressure can be reduced, and abnormal wear at the contact portion can be suppressed. By regulating the variation in the axial position of the flat surface within the standard value, the axial position of the constant velocity universal joint is accurately defined, so that the offset amount between the center of the kingpin and the center of the joint is minimized, or Both can be completely matched, and the running stability of the vehicle can be improved.

The flat surface is formed after the plastic deformation of the caulked portion. At this time, if the flat surface is formed by press working, the swaged portion protrudes to the inner diameter side due to the material flow accompanying the press, and it may be difficult to insert the outer joint member into the inner periphery of the first inner member, It is desirable to perform the flat surface by machining (turning or grinding). “Machine processing” is a processing method of removing and shaping a material, and can surely avoid the above-mentioned adverse effects.

It is desirable that the above standard value is set to ± 0.2 mm. If the standard value is out of the range of the numerical value, the offset amount that can occur between the kingpin center and the joint center becomes so large that it cannot be ignored, and the running stability of the vehicle is impaired.

Further, if the variation in the perpendicularity of the flat surface with respect to the axis is regulated within a standard value, the whirling of the flat surface can be prevented, and the sealing performance at the contact portion can be improved. . The standard value of this squareness is 0.15 m
It is desirable to set m.

If there is a large difference in hardness between the flat surface of the caulked portion and the surface portion of the outer joint member that comes into contact with the flat surface, there is a concern that fretting wear and sealing performance may be reduced at the contact portion. Therefore, it is desirable that these hardnesses are set to be substantially the same.

The outer joint member is provided with a torque transmitting portion for transmitting torque between the outer joint member and the first inner member. Of the outer joint member, at least including the torque transmitting portion, and forming a surface hardened layer by heat treatment in a region other than the contact portion with the flat surface, to increase the rigidity of the torque transmitting portion and between the outer joint member and the first inner member. In this case, the hardness of the contact portion with the flat surface can be made substantially the same as that of the flat surface which is usually unhardened.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given based on FIG. In the following description, a side closer to the outside of the vehicle when assembled to the vehicle is called an outboard side, and a side closer to the center of the vehicle is called an inboard side. In each of the above figures, the left side is the outboard side, and the right side is the inboard side.

FIG. 1 shows a bearing device for a drive wheel according to a first embodiment of the present invention, in which a double-row rolling element 50 is incorporated between an outer member 10 and an inner member 20 to form an inner member. 20 is a structure for rotatably supporting 20. The double-row rolling elements 50 are held at equal intervals in the circumferential direction by the cage 60, and roll on each of the races between the outer race 11 and the inner races 21 and 22 in the double-row. Here, the case where a ball is used as the rolling element 50 is illustrated, but a tapered roller can also be used.

The outer member 10 has a double row outer race 11 on the inner periphery and a vehicle body mounting flange 12 for mounting on a vehicle body side mounting member, for example, a knuckle extending from a suspension device, on the outer circumference. Seals 13 and 14 are attached to both ends of the outer member 10 to prevent leakage of grease filled therein and entry of water and foreign matter from the outside.

The inner member 20 is composed of a first inner member 30 and a second inner member 40 fitted around the first inner member 30. The present embodiment exemplifies a case where the inner member 20 is formed by fitting a ring-shaped inner ring 40 as a second inner member to the outer periphery of a hub wheel 30 as a first inner member. A wheel mounting flange 31 for mounting a wheel is integrally formed on the outer periphery of the hub wheel 30 on the outboard side. Hub bolt 3 implanted in this flange 31
By 5, a drive wheel (not shown) is fastened and fixed to the wheel mounting flange 31 via the brake rotor. On the other hand, a small-diameter cylindrical portion 3 is provided around the inboard side of the hub wheel 30.
The inner ring 40 is press-fitted into the small-diameter cylindrical portion 32. Of the inner races 21 and 22, the inboard race 21 is formed on the outer periphery of the inner race 40, and the outboard race 22 is formed directly on the outer periphery of the hub wheel 30. A mounting hole 23 for mounting an outer joint member 72 of a constant velocity universal joint 70 described later is formed through the shaft center of the hub wheel 30.

The hub wheel 30 and the inner ring 40 are formed by plastically deforming the end of the hub wheel 30 protruding from the inner ring 40 to the outer diameter side by means of rocking caulking or the like, and radially caulking portions formed by plastic deformation. 37 is the inboard end surface 41 of the inner race 40 (rear surface).
Are connected inseparably. The caulking portion 37 positions the inner race 40 in the axial direction with respect to the hub wheel 30, and applies a predetermined preload to the rolling elements 50.

In the upper half of the center line in FIG. 1, the hatching representing the cross section is omitted, and the surface hardened layer formed by the heat treatment is indicated by hatching instead (in the lower half of the center line, the illustration of the surface hardened layer is omitted. There). The hub wheel 30 is formed by forging using carbon steel or the like having a carbon content of 0.45 to 1.10% by weight, and a portion indicated by hatching, that is, a base end of the wheel mounting flange 31. Beginning near the club, inner race 2 on the outboard side
2. A hardened surface layer of about Hv 510 to 900 is formed by heat treatment in a region from a shoulder surface 38, which is a butt surface with the inner ring 40, to an outer peripheral surface, which is a fitting portion (small-diameter cylindrical portion 32) with the inner ring 40. You.

The caulking portion 37 at the inboard end of the hub wheel 30 is required to have sufficient ductility to enable caulking, and thus is left as an unquenched portion that is not subjected to a hardening process. Specifically, by setting the hardness in the range of Hv200 to 300, ductility that can be crimped can be maintained.

The quenching method can be selected from known techniques such as induction quenching, carburizing quenching, and laser quenching. In the case where heat treatment is performed in the above-described quenching pattern, induction quenching is suitable. Induction quenching as a surface hardening treatment makes it possible to freely select a hardened layer by effectively utilizing the characteristics of induction heating, to provide wear resistance and improve fatigue strength. In particular, since the depth of the hardened layer can be freely selected and controlled so as not to exert a significant thermal effect on the portions other than the hardened layer, the performance of the base material can be maintained.
This is advantageous when a partially unquenched part is left in the base material as in FIG.

The same quenching and hardening treatment is applied to the entire surface of the inner ring 40, though not particularly shown. In addition, the core may be subjected to a hardening treatment by quenching.

This wheel bearing device includes a constant velocity universal joint 70.
Is assembled. The constant velocity universal joint 70 transmits the torque from the drive shaft to the outer joint member 72 via the inner joint member 74 and the torque transmitting ball 75. The outer joint member 72 includes a cup-shaped mouth portion 72a and a shaft-shaped stem portion 72b that are closed at one end (outboard side) and open at the other end (inboard side).
A plurality of track grooves 71 are formed in the inner peripheral portion of 2a. A plurality of ball tracks are formed in cooperation with the track grooves 71 and a plurality of track grooves 73 provided on the outer peripheral portion of the inner joint member 74, and a constant velocity universal joint is formed by disposing a torque transmitting ball 75 in each ball track. 70 are configured. Each torque transmitting ball 75 is held by a cage 76 on a bisecting plane between the two axes.

The stem portion 72b of the outer joint member 72 is inserted into the mounting hole 23 of the hub wheel 30. Hub wheel 30
The outer joint member 72 is connected to the outer joint member 72 via a torque transmission means 81 such as a serration or a spline so as to be able to transmit a torque. Screw portion 7 formed at the shaft end of stem portion 72b
By screwing nut 82 into 2c and tightening,
The constant velocity universal joint 70 is fixed to the hub wheel 30. In this case, since the application of the preload has already been performed by the caulking portion 37, the tightening of the nut 82 is sufficient to prevent separation of the constant velocity universal joint 70 and the hub wheel 30. Therefore,
Compared to the conventional product (see FIG. 5) which required a large tightening torque to secure the preload after assembling, the nut 82
Can be greatly reduced. As the nut 82 is tightened, the inboard end surface of the caulked portion 37 contacts the shoulder 72 d of the outer joint member 72.

As shown in an enlarged manner in FIG.
A flat surface 38 in a direction perpendicular to the axis is formed on the inboard side end surface of. When the caulked portion 3a is left in a crimped shape as in the conventional product shown in FIG. 6, the caulked portion 3a and the shoulder 7a1 of the outer joint member 7a are in line contact with each other, and an excessive surface pressure is applied to both. Acts, which may cause abnormal wear on the caulked portion 3a and the shoulder 7a1. On the other hand, as described above, the contact portion of the caulking portion 37 with the shoulder 72d is formed on the flat surface 3d.
8, the caulking portion 37 and the shoulder 72d are flat surfaces 38.
As a result, the contact surface pressure can be reduced, and abnormal abrasion of the contact portion can be suppressed.

The flat portion 38 can be formed, for example, by pressing the caulking portion 37. In the press, the base end of the caulking portion 37 protrudes toward the inner diameter side due to the material flow due to the press pressure, and the outer joint is formed. There is a possibility that the operation of inserting the member 72 may be hindered. Therefore, it is desirable that the flat surface 38 be formed by subjecting the end face of the caulked portion 37 to machining (machining) such as turning or grinding to remove a material.

By the way, even when the flat surface 38 is formed on the caulking portion 37 as described above, if there is a variation in the axial position of the flat surface 38, the caulking portion 37 and the outer joint member 72 are not provided.
The constant velocity universal joint 70 and the hub wheel 30
And the relative axial position of the joint pin varies, making it difficult to match the joint center O with the center of the kingpin.
When the kingpin center does not coincide with the joint center O, the running stability of the vehicle may be impaired. Also, if the squareness of the flat surface 38 is not ensured,
It is also anticipated that dust may enter from the abutting portion with the end surface of the shoulder 72d and cause rust on the torque transmitting portion 81, making it difficult to remove the outer joint member 72 from the hub wheel 30 during repair or the like.

In order to solve this problem, in the present invention, the variation in the axial position of the flat surface 38 is restricted within a standard value.
As a result, the offset amount between the joint center O and the kingpin center can be minimized, or the two can be completely matched, so that the running stability of the vehicle can be improved and the seal at the contact portion of the flat surface 38 can be improved. Can be avoided.

The standard value is defined by the axial thickness L of the caulking portion 37 shown in FIG. 2, that is, the variation of the axial dimension between the flat surface 38 and the inboard end surface 41 of the inner ring 40.
In the present invention, the value is set to ± 0.2 mm. Flat surface 3
8 is formed by machining with an accuracy within this standard value, but the reference surface at the time of machining is, for example, the outboard end surface 31a of the wheel mounting flange 31 or the inboard end surface 12a of the vehicle body mounting flange 12. Can be. The former is convenient for the reference surface because it is formed with high accuracy to ensure the mounting accuracy of the knuckle, and the latter is convenient for securing the mounting accuracy of the brake rotor. It is possible to easily obtain the thickness L within the standard value.

The perpendicularity is determined by the axis to be perpendicular and the flat surface 3.
In combination with 8, the magnitude of the deviation of the other plane part or straight part from the geometric plane or straight line perpendicular to this reference straight line or reference plane with respect to one of them. In the present invention, the perpendicularity between the flat surface 38 and the axis is set within 0.15 mm, whereby the sealing performance at the contact portion between the caulked portion 37 and the shoulder 72d can be further improved.

In addition, the perpendicularity between the flat surface 38 and the axis is managed indirectly by controlling the parallelism between the outboard side end surface 31a of the wheel mounting flange 31 and the flat surface 38. Can be.

By the way, in the conventional product shown in FIG. 5, as shown by hatching in FIG. 7, on the outer periphery of the outer joint member 7, a male torque transmitting portion 7a2, a slim portion 7a3, A continuous hardened layer S 'is formed on the shoulder 7a1. Among them, the torque transmitting portion 7a2 is hardened in order to secure the strength when transmitting torque to and from the hub wheel 3. Also, shoulder 7a1
Are hardened in connection with the fact that the surface of the inner ring 4 has been subjected to a hardening hardening treatment. That is, if the shoulder portion 7a1 is not quenched while the inner ring 4 is subjected to the quench hardening treatment, the difference in hardness between the inner ring 4 and the shoulder portion 7a1 becomes large, which causes the occurrence of fretting wear and a decrease in sealing performance. Has been cured to avoid this.

On the other hand, in the present invention, since the caulking portion 37 in contact with the shoulder 72d is not hardened as described above, if a surface hardened layer is formed on the shoulder 72d as in the prior art, the hardness of both is increased. The difference becomes large, and the above-mentioned inconvenience occurs. Therefore, in the present invention, as shown in FIG.
The heat treatment of the d surface is abolished, and this portion is not quenched to secure the same hardness as the caulked portion 37. That is,
As shown in FIG. 3, the surface hardened layer S of the outer joint member 72
Is stopped in the region from the torque transmitting portion 72e to the slimming portion 72f, and at least the crimped portion 3
The portion in contact with 7 has no thermal effect, and the cured layer S is omitted. The hardened surface layer S of the outer joint member 72 is desirably formed by induction hardening similarly to the hardened hardened layer of the hub wheel 30.

When the shoulder 72d and the caulking portion 37 are not hardened as described above, the rigidity of the caulking portion 37 and the shoulder 72a may be insufficient. However, in the present invention, the bearing is formed by caulking as described above. Since a preload is applied to the inside, the surface pressure acting on these contact portions is significantly smaller than that of the conventional product shown in FIG. 5, so that such insufficient rigidity does not pose a problem.

FIG. 4 shows another embodiment of the drive wheel bearing device. This bearing device has two inner rings 42, 4 as a second inner member on the outer periphery of the hub wheel 30 as a first inner member.
3 are fixed, and double rows of inner races 21 and 22 are formed on the outer periphery of both inner rings 42 and 43, respectively. The inner rings 42 and 43 are press-fitted into the outer periphery of a small-diameter cylindrical portion 32 formed on the outer periphery of the hub wheel 30 in a state of abutting. In contact. By forming the caulking portion 37 by plastically deforming the inboard end of the hub wheel 30 to the outer diameter side, the inner wheels 42 and 43 and the hub wheel 30 are integrated and preloading is performed. From the state shown in FIG.
An outer joint member (not shown) is fitted to the inner periphery of the shaft, and the nut is tightened to complete the assembly of the drive wheel bearing device (the members having the same functions and functions as the bearing device shown in FIG. 1 have the same reference numerals). To avoid duplication of explanation).

Also in this bearing device, the same effects as described above can be obtained by applying the structure of the present invention described with reference to FIGS.

[0037]

As described above, according to the present invention, the portion of the caulked portion that comes into contact with the outer joint member is made a flat surface, and the variation in the axial position of this flat surface is restricted to within a standard value. Therefore, the offset amount between the joint center O and the kingpin center can be minimized, or both can be completely matched. Therefore, it is possible to improve the running stability of the vehicle and to avoid a decrease in the sealing performance at the contact portion.

[Brief description of the drawings]

FIG. 1 is a sectional view of a drive wheel bearing device according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part in FIG.

FIG. 3 is an enlarged sectional view showing a main part in FIG. 1;

FIG. 4 is a sectional view showing another embodiment of the drive wheel bearing device.

FIG. 5 is a sectional view of a conventional drive wheel bearing device.

FIG. 6 is an enlarged cross-sectional view of a drive wheel bearing device that performs positioning of an inner ring and application of preload by crimping.

FIG. 7 is an enlarged sectional view showing a main part in FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 outer member 11 outer race 20 inner member 21 inner race (inboard side) 22 inner race (outboard side) 30 first inner member (hub ring) 37 crimping portion 38 flat surface 40 second inner member (inner ring) 50 Rolling element 70 Constant velocity universal joint 72 Outer joint member 72d Shoulder 72e Torque transmitting part

Claims (7)

[Claims] 1. An outer member having a double-row outer race on the inner periphery, and at least one of a double-row inner race, a first inner member, and a double-row inner race facing the outer race of the outer member. Comprising a formed second inner member,
An inner member in which the first inner member and the second inner member are non-separably coupled by a radially caulked portion formed by plastically deforming the first inner member to the outer diameter side; an outer member and an inner member And a double-row rolling element interposed between the outer joint member of the constant velocity universal joint and the inner periphery of the first inner member so as to be able to transmit a torque. In the drive wheel bearing device to be abutted, a portion of the caulked portion that abuts on the outer joint member is a flat surface, and a variation in an axial position of the flat surface is restricted to a standard value. Bearing device for drive wheels. 2. The drive wheel bearing device according to claim 1, wherein the flat surface is formed by machining. 3. The drive wheel bearing device according to claim 1, wherein the standard value is ± 0.2 mm. 4. The drive wheel bearing device according to claim 1, wherein a variation in the perpendicularity of the flat surface with respect to the shaft center is regulated within a standard value. 5. The drive wheel bearing device according to claim 4, wherein the standard value is 0.15 mm. 6. The hardness of the flat surface of the caulked portion and the hardness of the surface portion of the outer joint member abutting on the flat surface.
The bearing device for a drive wheel according to any one of claims 5 to 5. 7. The outer joint member is provided with a torque transmitting portion for transmitting torque between the outer joint member and the first inner member. The outer joint member includes at least the torque transmitting portion and includes a contact portion with a flat surface. The drive wheel bearing device according to any one of claims 1 to 6, wherein a surface hardened layer is formed by heat treatment in a region except for the region.