JP2002114005A - Bearing device for driving wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the service life by restricting the deflection inside a bearing caused by the deformation of an inner ring and a hub wheel by a load in the contact angle direction. SOLUTION: This bearing device for driving wheel is formed of an outer ring 5 formed with double row raceway surfaces in the inner surface thereof, a hub wheel 1 formed with a raceway surface 7 opposite to the raceway surfaces 12 and 13 of the outer ring 5 and a wheel fitting flange 9 in the outer peripheral surface thereof and having a caulking part 31 plastically deformed to the outer diameter side at an end thereof, an inner ring 2 pressed into a small diameter part of the hub wheel 1 and formed with the other raceway surface 8 in the outer peripheral surface thereof, double rolling elements 3 and 4 interposed between the raceway surfaces of the outer ring 5, the hub wheel 1 and the inner ring 2, and a constant velocity universal joint 6 having a joint outer ring 21 provided with a shaft part 23 fitted in the hub wheel 1 possible to transmit the torque through serration parts 24 and 25. A pilot part 35 is provided between a root part of the shaft part of the joint outer ring 21 and the small diameter part 11 of the hub wheel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive wheel bearing device, and more particularly to a drive wheel bearing device for rotatably supporting a drive wheel of an automobile on a vehicle body.

[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, a bearing device for a drive wheel shown in FIG. 2 mainly includes a hub wheel 1 and an inner ring 2, which are inner members, double-row rolling elements 3, 4, an outer ring 5, which is an outer member, and a constant velocity universal joint 6. It is a component.

The hub wheel 1 has a track surface 7 on the outboard side formed on an outer peripheral surface thereof, and a wheel (not shown).
Is provided with a wheel mounting flange 9 for mounting.
Hub bolts 10 for fixing the wheel disc are implanted at equal intervals in the circumferential direction of the wheel mounting flange 9. The inner ring 2 is fitted to a small-diameter step portion 11 formed on the outer peripheral surface of the inboard end of the hub wheel 1, and an inboard-side raceway surface 8 is formed on the outer peripheral surface of the inner ring 2.

[0004] The inner ring 2 is press-fitted with an appropriate interference to prevent creep. The raceway surface 7 on the outboard side formed on the outer peripheral surface of the hub wheel 1 and the raceway surface 8 on the inboard side formed on the outer peripheral surface of the inner ring 2 constitute a double row raceway surface. The inner ring 2 is press-fitted into the small-diameter step portion 11 of the hub wheel 1, and the joint outer ring 21 of the constant velocity universal joint 6 inserted from the inboard axial direction of the hub wheel 1 is fastened to the hub wheel 1, whereby the inner ring 2 The shoulder 28 of the joint outer ring 21 is abutted against the end of the inner ring 2 to prevent the inner ring 2 from coming off and to control the preload.

The outer ring 5 has track surfaces 12, 13 facing the track surfaces 7, 8 of the hub wheel 1 and the inner ring 2 on its inner peripheral surface, and a vehicle body mounting flange 14 for mounting to a vehicle body (not shown). It has. This body mounting flange 14
Is bolted to a knuckle extending from a suspension (not shown) of the vehicle body.

The bearing portion 15 has a double-row angular contact ball bearing structure, and has raceway surfaces 7, 8 formed on the outer peripheral surfaces of the hub wheel 1 and the inner ring 2 and raceway surfaces 12, 8 formed on the inner peripheral surface of the outer ring 5. 1
3, rolling elements 3 and 4 are interposed, and rolling elements 3
4 is supported at equal intervals in the circumferential direction by retainers 16 and 17.

A pair of seals 18 and 19 for sealing the annular space between the outer ring 5 and the hub ring 1 and the inner ring 2 are fitted into the opening at both ends of the bearing part 15 at the inner diameter of the end of the outer ring 5 to fill the inside. The grease is prevented from leaking and water or foreign matter from the outside is prevented from entering.

The constant velocity universal joint 6 has a drive shaft 39.
And a joint outer ring 21 having a track groove 20 formed on an inner peripheral surface thereof, and a track groove 20 of the joint outer ring 21.
A ball 4 incorporated between the track groove 20 of the joint outer ring 21 and the track groove 40 of the joint inner ring 41, and a joint inner ring 41 having a track groove 40 facing the
2 and a retainer 43 that supports the ball 42 between the joint outer ring 21 and the joint inner ring 41.

The joint outer ring 21 has a mouth portion 22 accommodating the joint inner ring 41, the ball 42 and the retainer 43, and extends integrally from the mouth portion 22 in the axial direction, and a serration portion 24 is formed on the outer peripheral surface. It has a shaft portion 23. The shaft portion 23 is inserted into the through hole of the hub wheel 1, and both are fitted by serration portions 24 and 25 formed on the outer peripheral surface of the shaft portion 23 and the inner peripheral surface of the through hole, and formed at the shaft end. The constant velocity universal joint 6 is fixed to the hub wheel 1 by tightening a nut 27 to the male screw portion 26 thus formed. Preload management is performed by applying an axial force by tightening the nut 27.

As described above, in the driving wheel bearing device of FIG. 2, the preload is controlled by the tightening torque of the nut 27. However, in the caulking type driving wheel bearing device shown in FIG. Preload management by torque is not required.

That is, in this type of bearing device for a drive wheel, the projecting end of the small-diameter stepped portion 11 of the hub wheel 1 is caulked to the outer diameter side by plastic deformation, and the caulked portion 31 prevents the inner ring 2 from coming off. Preload management is performed. Therefore, the joint outer ring 21 of the constant velocity universal joint 6 is fixed by a nut, a bolt, a clip, or the like to such an extent that it does not come off from the hub wheel 1.

For example, in the drive wheel bearing device of FIG.
The shaft portion 23 of the joint outer ring 21 is inserted into the through hole of the hub wheel 1,
By screwing a bolt 33 into a screw hole 32 formed in the shaft portion 23, the joint outer ring 21 is fixed to the hub wheel 1 so as not to be pulled out.

[0013]

By the way, in the drive wheel bearing device shown in FIG. 3, it is not necessary to control the preload by the tightening torque of the nuts and bolts, and to add the protruding end of the small diameter step portion 11 of the hub wheel 1. By integrating the hub wheel 1 and the inner ring 2 by tightening, the preload management by the crimping portion 31 of the hub wheel 1 can be easily performed.

On the other hand, in the drive wheel bearing device having a structure in which balls are used for the rolling elements 3 and 4, the contact angle of the inner ring 2 is about 35 °. It is also received by the swaged portion 31 of the hub wheel 1 abutted against the shoulder 28. Here, the contact angle is
It means the angle formed by the acting direction of the force transmitted to the rolling elements 3 and 4 by the raceway surfaces 7 and 8 with respect to a plane (radial plane) perpendicular to the bearing center axis.

Therefore, the load in the contact angle direction causes the hub wheel 1
The small-diameter step portion 11 and the raceway surface 8 of the inner ring 2 are easily deformed. When the amount of deformation of the small-diameter step portion 11 of the hub wheel 1 increases, the breakage of the hub wheel 1 and fretting between the hub wheel 1 and the inner ring 2 easily occur. When the amount of deformation of the raceway surface 8 of the inner race 2 increases, the rolling life decreases, the temperature increases on the raceway surface 8, and the axial force (preload) due to fretting between the inner race 2 and the shoulder 28 of the joint outer race 21. Dropouts are likely to occur. When the small-diameter step portion 11 of the hub wheel 1 and the raceway surface 8 of the inner ring 2 are easily deformed in this way, the inside of the bearing may be distorted, and the life of the bearing device may be shortened.

Accordingly, the present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is to suppress distortion inside a bearing caused by deformation of a hub wheel and an inner ring due to a load in a contact angle direction to reduce the life. An object of the present invention is to provide a drive wheel bearing device that can be improved.

[0017]

SUMMARY OF THE INVENTION As a technical means for achieving the above object, the present invention provides an outer member having a double row of track surfaces formed on an inner peripheral surface, and a track surface of the outer member. Opposite raceway surfaces and wheel mounting flanges are formed on the outer peripheral surface, respectively, and an inner member having a caulked portion whose end is plastically deformed toward the outer diameter side, and respective raceway surfaces of the outer member and the inner member. A double-row rolling element interposed therebetween, and a constant velocity universal joint having a joint outer ring in which a shaft portion is internally fitted to the inner member so that torque can be transmitted via a serration portion, In a bearing device for a driving wheel for rotatably supporting a wheel, a pilot portion is provided between a root portion of a shaft portion of the joint outer ring and an end portion of the inner member (claim 1). The pilot clearance is 0.4mm
It is desirable to set the following (claim 2).

In the first and second aspects of the present invention,
By providing the pilot portion between the shaft base portion of the joint outer ring and the end of the inner member, it is possible to suppress the deformation of the end of the inner member due to the load in the contact angle direction,
The life of the bearing device can be easily improved.

According to the present invention, a double-row raceway surface is
Further, the present invention can be applied to a drive wheel bearing device having a structure in which an outer member having a vehicle body mounting flange integrally formed on an outer peripheral surface thereof is provided.

The present invention also provides a hub wheel having a wheel mounting flange, one raceway surface and a small diameter step formed on an outer peripheral surface,
The present invention is applicable to a drive wheel bearing device having an inner member that is fitted to the small-diameter step portion and includes a separate inner ring having the other raceway surface formed on the outer peripheral surface (claim 4).

[0021] The invention described in claim 5 is characterized in that the caulked portion of the inner member and the shoulder of the joint outer ring are abutted with each other by line contact. As described above, the crimped portion of the inner member and the shoulder of the outer ring of the joint are brought into contact with each other by line contact, thereby suppressing abnormal noise generated between the crimped portion of the inner member and the shoulder outside the joint. it can. In the structure described in claim 5, it is desirable that the serration portion formed on the shaft portion of the inner member and the joint outer ring is fitted with a interference (claim 6).

The invention described in claim 7 is characterized in that the pilot portion is located on an extension of the contact angle between the inboard raceway surface of the inner member and the rolling element. With this pilot portion, deformation of the end portion of the inner member due to the load in the contact angle direction can be reliably suppressed, and the life of the bearing device can be more easily improved.

The invention described in claim 8 is characterized in that the inner member and the shaft portion of the joint outer ring are fixed detachably in the axial direction by a locking member. In other words, the fixing between the inner member and the shaft of the outer ring of the joint is sufficient as long as the outer ring of the joint does not come off from the inner member. Therefore, in addition to fastening with a bolt or a nut, it is performed by a locking member such as a clip or a snap ring. It is possible.

It is preferable that a surface hardened layer is formed in a region extending from a base of the wheel mounting flange to an end of the inner member excluding the caulked portion. In this case, by increasing the surface hardness including the raceway surface of the inner member, the rolling fatigue life can be improved and fretting can be reduced.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a drive wheel bearing device according to the present invention will be described in detail below. 2 and 3 are denoted by the same reference numerals.

The embodiment shown in FIG. 1 is a caulking type bearing device for a drive wheel. For example, a hub wheel 1 and an inner ring 2, which are inner members, double-row rolling elements 3, 4, and an outer member. An outer ring 5 and a constant velocity universal joint 6 are main components.

The hub wheel 1 has a track surface 7 on the outboard side formed on the outer peripheral surface thereof and a wheel (not shown).
Is provided with a wheel mounting flange 9 for mounting.
Hub bolts 10 for fixing the wheel disc are implanted at equal intervals in the circumferential direction of the wheel mounting flange 9. The inner ring 2 is fitted to a small-diameter step portion 11 formed on the outer peripheral surface of the inboard end of the hub wheel 1, and an inboard-side raceway surface 8 is formed on the outer peripheral surface of the inner ring 2.

The inner ring 2 is press-fitted with an appropriate interference to prevent creep. The raceway surface 7 on the outboard side formed on the outer peripheral surface of the hub wheel 1 and the raceway surface 8 on the inboard side formed on the outer peripheral surface of the inner ring 2 constitute a double row raceway surface. The protruding end of the small-diameter step portion 11 of the hub wheel 1 is crimped to the outer diameter side by plastic deformation, and the crimping portion 31 prevents the inner ring 2 from coming off and manages the preload.

The outer ring 5 has track surfaces 12 and 13 formed on the inner peripheral surface thereof facing the track surfaces 7 and 8 of the hub wheel 1 and the inner ring 2, and a vehicle body mounting flange 14 for mounting to a vehicle body (not shown). It has. This body mounting flange 14
Is bolted to a knuckle extending from a suspension (not shown) of the vehicle body.

The bearing portion 15 has a double-row angular contact ball bearing structure, and has raceway surfaces 7, 8 formed on the outer peripheral surfaces of the hub wheel 1 and the inner ring 2 and raceway surfaces 12, 8 formed on the inner peripheral surface of the outer ring 5. 1
3, rolling elements 3 and 4 are interposed, and rolling elements 3
4 is supported at equal intervals in the circumferential direction by retainers 16 and 17.

A pair of seals 18 and 19 for sealing the annular space between the outer ring 5 and the hub ring 1 and the inner ring 2 are fitted into the opening at both ends of the bearing part 15 at the inner diameter of the end of the outer ring 5 to fill the inside. The grease is prevented from leaking and water or foreign matter from the outside is prevented from entering.

The constant velocity universal joint 6 includes a drive shaft 39
And a joint outer ring 21 having a track groove 20 formed on an inner peripheral surface thereof, and a track groove 20 of the joint outer ring 21.
A ball 4 incorporated between the track groove 20 of the joint outer ring 21 and the track groove 40 of the joint inner ring 41, and a joint inner ring 41 having a track groove 40 facing the
2 and a retainer 43 that supports the ball 42 between the joint outer ring 21 and the joint inner ring 41.

The joint outer ring 21 has a mouth portion 22 accommodating the joint inner ring 41, the ball 42 and the retainer 43, and extends integrally from the mouth portion 22 in the axial direction, and a serration portion 24 is formed on the outer peripheral surface. It has a shaft portion 23. The shaft portion 23 is inserted into the through hole of the hub wheel 1, and both are fitted by serration portions 24 and 25 formed on the outer peripheral surface of the shaft portion 23 and the inner peripheral surface of the through hole, and formed at the shaft end. The constant velocity universal joint 6 is fixed to the hub wheel 1 by tightening a nut 27 to the male screw portion 26 thus formed. The serrations 24 and 25 include splines other than serrations.

In the drive wheel bearing device of this embodiment,
By prestressing the protruding end of the small-diameter step portion 11 of the hub wheel 1 to integrate the hub wheel 1 and the inner ring 2, preload management is performed by the swaged portion 31 of the hub wheel 1. for that reason,
The fixing of the joint outer ring 21 to the hub wheel 1
May be tightened by the nut 27 to such an extent that the shaft portion 23 does not come off the hub wheel 1. In addition to the fastening with a nut or a bolt, the shaft portion 23 of the joint outer ring 21 can be detachably fixed to the hub wheel 1 by a locking member (not shown) such as a clip or a snap ring.

In the bearing device for a driving wheel according to the embodiment using balls for the rolling elements 3 and 4, the contact angle is 35 °.
Therefore, the load acting in the contact angle direction of the inner ring 2 is received by the crimping portion 31 of the hub wheel 1 abutted against the shoulder 28 of the joint outer ring 21. Therefore, in this embodiment, the pilot portion 35 is provided between the shaft root portion 34 of the joint outer ring 21 and the small-diameter step portion 11 which is the end of the hub wheel 1.
Is provided. The pilot portion 35 is located on an extension of the contact angle between the inboard raceway surface 8 of the inner race 2 and the rolling element 4.

The pilot portion 35 is formed by increasing the outer diameter of the shaft root portion 34 of the joint outer ring 21 and further increasing the inner diameter of the small-diameter step portion 11 of the hub wheel 1 from the serration portion 25. You. Thus, the pilot portion 35 is formed, and the pilot portion clearance a is set to 0.4 m.
m or less. Here, the pilot portion clearance a means a difference between the inner diameter of the small diameter step portion 11 of the hub wheel 1 and the outer diameter of the shaft root portion 34 of the joint outer ring 21.

With the provision of the pilot portion 35 in this manner, the small-diameter step portion 1 of the hub wheel 1 is subjected to a load in the contact angle direction.
1 can be suppressed, preventing breakage of the hub wheel 1,
Fretting between the hub wheel 1 and the inner ring 2 can be reduced, and deformation of the raceway surface 8 of the inner ring 2 due to a load in the contact angle direction can be suppressed. Axial force (preload) can be prevented from dropping out by reducing fretting between the shoulder portion 28 of the outer ring 21 and the joint, and the life of the bearing device can be improved. If the clearance a of the pilot portion is larger than 0.4 mm, the desired effect of suppressing deformation of the small-diameter step portion 11 of the hub wheel 1 and the raceway surface 8 of the inner ring 2 cannot be obtained.

Also, by abutting the caulked portion 31 of the hub wheel 1 and the shoulder 28 of the joint outer ring 21 by line contact,
An abnormal sound generated between the caulked portion 31 of the hub wheel 1 and the shoulder 28 of the joint outer ring 21 can be suppressed. The serrations 24, 25 formed on the inner diameter of the hub wheel 1 and the outer diameter of the shaft 23 of the joint outer ring 21 are, for example, serrations 24.
It is preferable that fitting is performed with an interference by giving a torsion angle.

In the above-described embodiment, the surface hardened layer 36 is formed in a region (excluding the caulked portion 31) extending from the base of the wheel mounting flange 9 to the small-diameter step portion 11 of the hub wheel 1. The base of the wheel mounting flange 9 is the outer peripheral surface of the hub wheel 1 with which the seal lip of the seal 18 mounted on the outboard side end of the outer ring 5 slides, that is, the seal land portion, and the seal land portion extends from the raceway surface. The surface hardened layer 36 is formed in a region (excluding the caulked portion 31) extending through the small-diameter step portion 11 through 7.

At each part of the surface hardened layer 36 and at the seal land, the seal lip of the seal 18 slides, so that abrasion resistance is required. On the raceway surface 7, the rolling element 3 rolls, so that the life resistance is required. Since the small-diameter step portion 11 is fitted with the inner ring 2, creep resistance and fretting resistance are required. Since the caulked portion 31 is required to have ductility, it is not necessary to form the surface hardened layer 36.

The heat treatment for forming the surface hardened layer 36 is preferably induction hardening. The high frequency heat treatment as the surface hardening treatment makes it possible to freely select the surface hardened layer 36 by effectively utilizing the characteristic of the induction heating, to provide wear resistance and to improve fatigue strength. Induction heating is a method in which electric energy is directly converted into heat energy in a metal using electromagnetic induction to generate heat, and high-frequency heat treatment using this method has many features. In particular, local heating is possible,
The depth of the hardened layer can be freely selected, and the hardened layer can be controlled so as not to significantly affect the heat except for the hardened layer, so that the performance of the base material can be maintained. Therefore, the caulked portion 31 can be left as an unquenched base material while a desired surface hardened layer 36 is formed in a region extending from the seal land portion to the small-diameter step portion 11 via the raceway surface 7.

[0042]

EXAMPLES For example, when a turning life test was performed due to a difference in dimensions of a pilot portion clearance, the following test results were obtained. Small-diameter stepped portion 11 of hub wheel 1 and outer ring 2 of joint
In the embodiment (see FIG. 1) in which a pilot gap a of 0.4 mm is formed between the shaft portion and the base portion 34 of FIG. Was.

On the other hand, in the comparative example without the pilot unit 35 (see FIG. 3), the operation time was 83 hours,
Temperature rise: Only a life test result of 60 to 80 ° C. was obtained.

From this test result, it is clear that the operating time of the drive wheel bearing device of the embodiment is three times or more that of the comparative example and the temperature rise is suppressed, so that the life of the bearing device can be easily improved. It is.

[0045]

According to the present invention, the pilot portion is provided between the base portion of the shaft portion of the outer race of the joint and the end portion of the inner member. Deformation can be suppressed, breakage of the inner member can be prevented, fretting of the inner member can be reduced, and the life of the bearing device can be improved. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention and showing a structural example of a bearing device for a drive wheel.

FIG. 2 is a sectional view showing an example of a structure in which a joint outer ring is fixed to a hub wheel by a nut in a conventional drive wheel bearing device.

FIG. 3 is a cross-sectional view showing an example of a structure in which a hub wheel and an inner ring are integrated by caulking in a conventional drive wheel bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner member (hub ring) 2 Inner member (inner ring) 3,4 Rolling element 5 Outer member (outer ring) 7,8 Track surface 9 Wheel mounting flange 12,13 Track surface 21 Joint outer ring 23 Shaft 28 Shoulder 31 Caulking part 34 Shaft base part 35 Pilot part

Claims (9)

[Claims] 1. An outer member having a double-row raceway surface formed on an inner peripheral surface, a raceway surface facing the raceway surface of the outer member, and a wheel mounting flange formed on an outer peripheral surface, and an end portion is formed on the outer peripheral surface. An inner member having a caulked portion plastically deformed to the radial side; a double row of rolling elements interposed between respective raceway surfaces of the outer member and the inner member; and a serration portion provided on the inner member. And a constant velocity universal joint having a joint outer ring in which a shaft portion is internally fitted so that torque can be transmitted through the shaft portion, and the drive wheel bearing device rotatably supports a wheel with respect to a vehicle body. A drive wheel bearing device, wherein a pilot portion is provided between a root portion and an end of the inner member. 2. The drive wheel bearing device according to claim 1, wherein the clearance of the pilot portion is 0.4 mm or less. 3. The wheel according to claim 1, wherein the outer member integrally has a double-row raceway surface on an inner peripheral surface thereof and a vehicle body mounting flange on an outer peripheral surface thereof. Bearing device. 4. The inner member is fitted with a wheel mounting flange, a hub wheel having an outboard-side raceway surface and a small-diameter step formed on an outer peripheral surface, and a small-diameter step, and has an inboard-side raceway formed on an outer periphery. The drive wheel bearing device according to any one of claims 1 to 3, comprising a separate inner ring formed on the surface. 5. The drive wheel bearing device according to claim 1, wherein the caulked portion of the inner member and the shoulder portion of the joint outer ring abut against each other by line contact. 6. The drive wheel bearing device according to claim 5, wherein the inner member and a serration portion formed on a shaft portion of the joint outer ring are fitted with an interference. 7. The drive wheel according to claim 1, wherein the pilot portion is located on an extension of a contact angle between a rolling surface and an inboard raceway surface of the inner member. Bearing device. 8. The drive wheel according to claim 1, wherein the inner member and the shaft portion of the joint outer ring are detachably fixed in the axial direction by a locking member. Bearing device. 9. The hardened surface layer is formed in a region extending from a base of the wheel mounting flange to an end of the inner member excluding the crimped portion. Bearing device for drive wheels.