JP2008018821A - Hub unit bearing for driving wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hub unit bearing for a driving wheel capable of properly suppressing abnormal sound generated in an abutting surface between a bearing and a driving shaft member. <P>SOLUTION: In this hub unit bearing 1, a hub 2 inserted and fixed with a constant velocity joint 20 is provided, and a female spline 2a formed on an inner peripheral surface of the hub 2 and a male spline 22a formed in the constant velocity joint 20 are constituted to be fitted to each other. A lubricating film having a lubricating effect by shot-peening using a nonferrous shot material is formed in at least one of the female spline 2a and the male spline 22a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hub unit bearing for a drive wheel, and more particularly to a hub unit bearing that realizes noise reduction on a contact surface between a bearing and a drive shaft member.

In a conventional drive wheel hub unit bearing, the side surface of the inner ring that contacts the drive shaft member (constant velocity joint) is a rough surface that increases the coefficient of friction with the constant velocity joint. It is known to suppress the occurrence of circumferential stick-slip (for example, see Patent Document 1).
Also, shot peening is applied to the contact surface of the constant velocity joint with the bearing to increase the frictional resistance between the constant velocity joint and the bearing, thereby making it difficult for relative rotation to occur. It is known to suppress the occurrence (see, for example, Patent Document 2).
JP 2005-24020 A JP 2003-118309 A

However, in the conventional drive wheel bearing unit described above, the stick-slip countermeasure is taken by making the contact surface between the constant velocity joint and the bearing rough, but the common metal between the bearing and the constant velocity joint is used. There is a high possibility that the contact surface fretting wears and the state of the original surface is lost due to the phenomenon, so that the stick-slip countermeasure effect may not be maintained.
Further, in the drive wheel bearing unit, fretting wear is likely to occur in the spline portion where the constant velocity joint and the bearing are fitted due to a change in the drive torque. When the wear of the spline part progresses due to the fretting wear and a gap is generated in the spline part, an abnormal noise phenomenon occurs in which the spline teeth come into contact with a change in driving torque.

Therefore, a method of delaying the progress of wear by putting a helix angle in the male spline can be considered, but it is not an effective countermeasure against abnormal noise because it does not suppress fretting wear itself due to the co-metal phenomenon.
Then, this invention makes it the subject to provide the hub unit bearing for drive wheels which can suppress appropriately the noise which generate | occur | produces in the contact surface of a bearing and a drive shaft member.

  In order to solve the above problems, a hub unit bearing for a drive wheel according to claim 1 includes an inner member having a hub on which a drive shaft member is inserted and fixed, and an outer circumferential surface formed with a raceway surface; A drive wheel comprising an outer member having a raceway surface opposite to the raceway surface of the member and arranged on the outer side of the inner member, and a plurality of rolling elements arranged to roll between the raceway surfaces. The inner member is configured such that a female spline formed on the inner peripheral surface of the hub and a male spline formed on the outer peripheral surface of the drive shaft member are fitted to each other. And at least one of the female spline and the male spline is characterized in that a lubricating coating having a lubricating effect is formed by shot peening using a non-ferrous shot material.

A drive wheel hub unit bearing according to a second aspect is the invention according to the first aspect, wherein the drive shaft member has a large diameter portion that abuts against an inner end side surface of the hub, and the large diameter portion and The lubricating coating is formed on at least one contact surface of the inner end side surface of the hub.
Furthermore, the hub unit bearing for a drive wheel according to claim 3 is the invention according to claim 1, wherein the inner member has an inner ring fitted on the hub, and the drive shaft member is an inner end of the inner ring. It has a large-diameter portion that contacts the side surface, and the lubricating coating is formed on at least one contact surface of the large-diameter portion and the inner end side surface of the inner ring.
The drive wheel hub unit bearing according to claim 4 is the invention according to any one of claims 1 to 3, wherein the lubricating coating is provided on a member of the inner member that contacts the drive shaft member. It is characterized by being formed.

  According to the hub unit bearing for a drive wheel according to the present invention, the lubricating film is formed by shot peening using a non-ferrous shot material on the spline fitting portion between the hub and the drive shaft member. The effect of suppressing wear and suppressing the generation of unpleasant noise can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing the structure of an embodiment of a bearing unit according to the present invention. In the hub unit bearing 1, a wheel-supporting rolling bearing 10 and a constant velocity joint 20 as a drive shaft member are unitized.
In the following description, when the hub unit bearing is mounted on a vehicle such as an automobile, the portion facing the vehicle width direction outer side is referred to as the outer end side portion, and the portion facing the vehicle width direction center side is the inner end. Called the side part. That is, in FIG. 1, the left side is the outer end side, and the right side is the inner end side.

The wheel support rolling bearing 10 includes a hub 2, an inner ring 3, an outer ring 4, and two rows of rolling elements 5. A wheel mounting flange 6 is provided on the outer end side portion of the outer peripheral surface of the hub 2, and a wheel and a brake rotor 30 (not shown) are fixed to the wheel mounting flange 6 via bolts 7.
Further, a cylindrical portion 8 having a small outer diameter is formed on the inner end side portion of the hub 2, and the inner ring 3 is press-fitted into the cylindrical portion 8, and the cylindrical portion 8 protrudes to the inner end side from the inner ring 3. The inner ring 3 and the hub 2 are caulked and fixed integrally by a caulking portion 8a whose tip portion is plastically deformed radially outward.

Further, a female spline 2 a that can be engaged with a male spline 22 a formed on the peripheral surface of the shaft 22 protruding from the outer ring 21 of the constant velocity joint 20 is provided on the inner surface of the central opening of the hub 2.
A raceway surface is formed on each of the axially intermediate portion of the outer peripheral surface of the hub 2 and the outer peripheral surface of the inner ring 3 to form inner ring raceway surfaces 16a and 16b. Further, outer ring raceway surfaces 17a and 17b corresponding to both inner ring raceway surfaces 16a and 16b are formed on the inner peripheral surface of the outer ring 4. Furthermore, between the inner ring raceway surfaces 16a and 16b and the outer ring raceway surfaces 17a and 17b, a plurality of rolling elements 5 are arranged so as to freely roll, and the inner ring 3 and the hub 2 are fixed integrally. A thing is rotatable inside the outer ring 4.

  Each rolling element 5 is held by a cage 9 so as to roll freely. In the case of a hub unit bearing for a relatively light vehicle such as a passenger car, a ball is often used as the rolling element. However, in the case of a heavy vehicle hub unit bearing, the rolling element Rollers are often used as For example, in the case of a hub unit bearing for a large automobile, a tapered roller is often used, and in the case of a hub unit bearing for a railway vehicle, a tapered roller or a cylindrical roller is often used.

Further, between the inner peripheral surface of the inner end side portion of the outer ring 4 and the outer peripheral surface of the inner end side portion of the inner ring 3, the inner peripheral surface of the outer end side portion of the outer ring 4 and the outer peripheral surface of the intermediate portion of the hub 2 In between, the sealing member 12 is provided, respectively.
On the outer peripheral surface of the outer ring 4, a suspension device mounting flange 13 is provided at an end portion on the side away from the wheel mounting flange 6. A suspension device (knuckle) 40 as a vehicle body side member is fixed to the suspension device attachment flange 13 via a bolt 14.

The wheel-supporting rolling bearing 10 and the constant velocity joint 20 having such a configuration include a female spline 2 a provided on the hub 2 of the wheel-supporting rolling bearing 10 and a male spline provided on the shaft 22 of the constant-velocity joint 20. 22a is engaged, and the nut 23 is screwed onto the screw 22b formed at the end of the shaft 22 to be fixed.
Further, the outer end surface 21a of the large-diameter portion of the outer ring 21 of the constant velocity joint 20 is fixed in a state where pressure is applied to the caulking portion 8a corresponding to the inner end side surface of the hub 2, thereby supporting the wheel. Appropriate preload is applied to the rolling elements 5 of the rolling bearing 10.

The contact surface with the constant velocity joint 20 in the wheel bearing rolling bearing 10, specifically, the female spline 2 a and the caulking portion 8 a of the hub 2 are shot peened using a non-ferrous shot material, which will be described later. A lubricating film having a lubricating effect is formed.
In order to assemble this bearing unit 1 in an automobile, the constant velocity joint 20 and a drive shaft (not shown) are engaged. The inner end portion of the drive shaft is coupled and fixed to an output shaft portion of a differential gear (not shown).
That is, when the automobile is running, the wheel-supporting rolling bearing 10 is used in a state in which a thrust load generated by the rotation of the drive shaft is applied in addition to the radial load generated by supporting the vehicle body with the wheels. .
In FIG. 1, the hub 2, the inner ring 3 and the constant velocity joint 40 correspond to inner members, and the outer ring 4 corresponds to an outer member.

FIG. 2 is a longitudinal sectional view showing the wheel-supporting rolling bearing 10 in a state where the constant velocity joint 20 is not inserted and fixed.
In this embodiment, as shown by a two-dot chain line in FIG. 2, non-ferrous shot material is formed on the female spline 2a and the caulking portion 8a of the hub 2 which are contact surfaces with the constant velocity joint 20 in the wheel bearing rolling bearing 10. A lubricating coating is formed by shot peening using
The shot peening process is performed by applying a non-ferrous shot material, and injecting the shot material from a shot nozzle of a projection device to collide with a work surface (hereinafter also referred to as a base material). Then, the surface of the shot material is melted by the frictional heat caused by the minute slip between the shot material and the base material surface when colliding with the base material, and is adhered onto the female spline 2a and the caulking portion 8a of the hub 2. It comes to form.

Here, as the shot material, a material having lubricity with respect to the iron-based material that is the material of the constant velocity joint 20, for example, tin, a copper-based alloy, zinc, or a thermoplastic resin is applied.
In such a film formation by shot peening, hydrogen is not generated in the process as in the case of electroplating or chemical plating, so there is no fear of delayed fracture or white peeling. Moreover, since it is not exposed to a high temperature in the treatment process unlike molten plating, a film can be formed without causing a decrease in the hardness of the base material and a change in the surface structure.

Furthermore, since a compressive residual stress layer is formed on the processed surface by the effect of shot peening, the strength of the work surface can be increased.
By the way, a hub unit bearing for a drive wheel in which a non-rotating outer ring is fitted or fixed to a knuckle, has a flange for fixing a wheel or a brake rotor to the hub, and a spline groove is provided on the inner peripheral side of the hub. Drive torque is received from the constant velocity joint via the spline, and the drive torque is transmitted to the wheel via the flange.

In such a drive wheel axle structure, the constant velocity joint comes into contact with the bearing at two locations: the abutting surface of the bearing and the spline. As described above, the constant velocity joint is a component that transmits driving torque, and its torsional amount is constantly changing due to changes in the transmission torque. Therefore, circumferential stick slip may occur at the abutting surface position. .
In particular, when the distance between the spline and the abutting surface is long, the torsion amount of the constant velocity joint increases, so that abnormal noise due to stick-slip is likely to occur.

As measures against this stick-slip noise, the side surface of the inner ring of the bearing that comes into contact with the constant velocity joint is a rough surface that increases the coefficient of friction with the constant velocity joint, and shot peening is applied to the contact surface of the constant velocity joint with the bearing. To increase the frictional resistance between the constant velocity joint and the bearing, thereby making it difficult for relative rotation to occur.
However, in these cases, the contact surface between the constant velocity joint and the bearing is roughened to take measures against stick-slip noise, but the friction coefficient due to the surface roughness is not stable and the bearing-constant velocity joint There is a high possibility that the original surface state is lost due to fretting wear on the surface due to the co-metallurgy phenomenon, and there is a possibility that the effect of measures against stick-slip noise cannot be maintained.

In addition, there is a method in which grease is applied to the contact surface between the constant velocity joint and the bearing to lower the coefficient of friction, and the slip is made before sound is produced, but in this case, the lubricant is washed away. And the effect of stick-slip noise countermeasures cannot be maintained.
Further, in the drive wheel bearing unit, fretting wear is likely to occur in the spline portion where the constant velocity joint and the bearing are fitted due to a change in the drive torque. When the wear of the spline part progresses due to the fretting wear and a gap is generated in the spline part, an abnormal noise phenomenon occurs in which the spline teeth come into contact with a change in driving torque.

Therefore, a method of delaying the progress of wear by putting a helix angle in the male spline can be considered, but it is not an effective countermeasure against abnormal noise because it does not suppress fretting wear itself due to the co-metal phenomenon.
On the other hand, in the present embodiment, non-ferrous shot material is applied to the female spline 2a and the caulking portion 8a of the wheel support rolling bearing 10 which are contact surfaces with the constant velocity joint 20 in the wheel support rolling bearing 10. A lubricating coating having a lubricating effect is formed by the shot peening used.

Thus, unlike plating, a lubricating coating can be appropriately formed without worrying about delayed fracture due to hydrogen charging, lowering the hardness of the base material due to high-temperature treatment, and loss of lubricant.
Further, since a residual compressive stress layer can be generated on the shot peening surface, the material strength can be increased. Therefore, by forming a film on the wheel-supporting rolling bearing 10, the bearing strength can be increased, and the bearing can be made thinner and lighter.

Further, by forming the lubricating coating on the female spline 2a, it is possible to suppress fretting wear due to the co-metal phenomenon on the contact surface between the female spline 2a and the male spline 22a.
Furthermore, by forming the lubricating film on the caulking portion 8a, the friction coefficient of the abutting surface between the wheel supporting rolling bearing 10 and the constant velocity joint 20 can be lowered, and slipping can be performed without sound. Further, fretting wear due to a co-metal phenomenon at the contact surface between the crimped portion 8a and the outer end surface 21a of the large diameter portion of the constant velocity joint 20 can be suppressed.

  As described above, in the above embodiment, the lubrication film by shot peening is formed on the spline fitting surface and the abutting surface with the constant velocity joint in the wheel bearing rolling bearing, and therefore, it is caused by the gap generated by fretting wear of the spline part. In addition to preventing abnormal noise, the stick-slip noise of the abutting surface can be prevented, and unpleasant noise of the vehicle can be prevented.

  In the above embodiment, the shot peening process can be performed either before or after the caulking portion 8a is plastically deformed. If specializing in measures against stick-slip, shot blasting is preferably performed after caulking. On the other hand, if it is considered including the reduction of friction with the caulking die during caulking, it is desirable to carry out at some point before caulking after the caulking inner diameter of the hub 2 is completed. When shot peening is performed before caulking, the surface is stretched by caulking, and therefore it is necessary to determine the processing conditions for shot peening so that a coating with an appropriate thickness can be formed in consideration of the thin lubricant film There is.

In the above embodiment, the case where the present invention is applied to a drive wheel hub unit bearing in which the hub 2 and the inner ring 3 are fixed by caulking has been described. However, the hub 2 and the inner ring 3 are not caulked. The present invention can also be applied to a hub unit bearing for a drive wheel that is fixed.
FIG. 3 is a longitudinal sectional view showing a configuration of a hub unit bearing for a drive wheel in which the hub 2 and the inner ring 3 are fixed without caulking. 3, parts having the same configurations as those of the hub unit bearing of FIG. 1 described above are denoted by the same reference numerals as those in FIG.

A cylindrical portion 8 having a small outer diameter is formed on the inner end side portion of the hub 2, and the inner ring 3 is press-fitted into the cylindrical portion 8.
The wheel support rolling bearing 10 and the constant velocity joint 20 include a female spline 2 a provided on the hub 2 of the wheel support rolling bearing 10 and a male spline 22 a provided on the shaft 22 of the constant velocity joint 20. The nut 23 is engaged with and fixed to the screw 22b formed at the end of the shaft 22.

That is, the outer end surface 21a of the large diameter portion of the outer ring 21 of the constant velocity joint 20 and the inner end surface 3a of the inner ring 3 are brought into contact with each other, and the hub 2 and the inner ring 3 are formed by the nut 23 and the outer end surface 21a of the constant velocity joint 20. Are sandwiched from the axial direction, the hub 2, the inner ring 3, and the constant velocity joint 20 are integrated. At the same time, an appropriate preload is applied to the rolling elements 5 of the wheel-supporting rolling bearing 10.
Then, as shown by the two-dot chain line in FIG. 4, the contact surface of the wheel support rolling bearing 10 with the constant velocity joint 20, specifically, the female spline 2 a of the hub 2 and the inner end surface 3 a of the inner ring 3, A lubricating coating having a lubricating effect is formed by shot peening using the non-ferrous shot material described above.

Thus, even when the hub 2 and the inner ring 3 are not caulked and fixed, the female spline 2a that is a contact surface with the constant velocity joint 20 in the wheel bearing rolling bearing 10 and the inner end face of the inner ring 3 If a lubricating coating by shot peening is formed on 3a, the same effect as in the above embodiment can be obtained.
In the above embodiment, the case where a single-layer lubricant film is formed by one shot peening process has been described. However, a plurality of processes are performed using a plurality of different shot materials to form a multilayer film. You can also

For example, the coating can have a two-layer structure, the surface side can be a coating made of a hard metal such as nickel, cobalt, or chromium, and the base material side can be a coating made of a base metal such as zinc that has a sacrificial rust prevention effect. This makes it possible to share roles such that the hard surface layer prevents wear and the inner sacrificial anticorrosive layer prevents the bearing from being oxidized.
In addition, the surface layer can be a film made of a metal more noble than iron such as tin or nickel, and the inner layer can be a film made of a base metal such as zinc. Thereby, the elution consumption by the sacrificial corrosion prevention of a base metal is prevented, and a higher rust prevention effect is obtained.

Thereby, generation | occurrence | production of the abnormal noise resulting from abrasion, rusting, etc. can be prevented. Thus, the effect which cannot be obtained by a single layer can be acquired by making a film into a multilayer.
Moreover, in the said embodiment, although the case where the lubricating film was formed in the wheel bearing rolling bearing 10 side was demonstrated, a lubricating film can also be formed in the constant velocity joint 20 side. That is, the large-diameter portion 21 that is a contact surface with the male spline 22a of the constant velocity joint 20 that is a fitting portion with the female spline 2a of the hub 2 or the caulking portion 8a of the hub 2 or the inner end surface 3a of the inner ring 3. The same effect as that of the above embodiment can also be obtained by forming a lubricating coating on the outer end surface 21a.

In addition, it is possible to form a lubricating coating by using different shot materials for the wheel supporting rolling bearing 10 side and the constant velocity joint 20 side. In this case, the role sharing effect can be obtained as in the multilayer structure described above.
In the above embodiment, the case where the present invention is applied to the third generation drive wheel hub unit bearing (Nippon Seiko Co., Ltd., hub III type) as shown in FIGS. It can be applied to a hub unit bearing for a drive wheel.

It is sectional drawing which shows the structure of the hub unit bearing in embodiment of this invention. It is sectional drawing which shows the structure of the rolling bearing for wheel support. It is sectional drawing which shows another example (non-caulking bearing) of a hub unit bearing. It is sectional drawing which shows another example (non-caulking bearing) of the rolling bearing for wheel support.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hub unit bearing, 2 ... Hub, 2a ... Female spline, 3 ... Inner ring, 3a ... Inner ring inner end surface, 4 ... Outer ring, 5 ... Rolling element, 6 ... Wheel mounting flange, 8a ... Clamping part, 9 ... Holding , 10 ... rolling bearings for supporting wheels, 12 ... sealing members, 13 ... flanges for mounting suspensions, 16a ... inner ring raceway surfaces, 16b ... inner ring raceway surfaces, 17a ... outer ring raceway surfaces, 17b ... outer ring raceway surfaces, 20 ... etc. High-speed joint, 21a ... large-diameter outer end surface, 22a ... male spline, 30 ... brake rotor, 40 ... suspension device (knuckle)

Claims (4)

An inner member having a hub on which the drive shaft member is inserted and fixed and having a raceway surface formed on the outer peripheral surface, and a raceway surface opposite to the raceway surface of the inner member, and disposed outside the inner member. A hub unit bearing for a drive wheel, comprising: the outer member made and a plurality of rolling elements arranged to roll between the both raceway surfaces,
The inner member is configured such that a female spline formed on the inner peripheral surface of the hub and a male spline formed on the outer peripheral surface of the drive shaft member are fitted, and the female spline and the male spline are formed. A hub unit bearing for a drive wheel, wherein a lubricating coating having a lubricating effect is formed on at least one of the splines by shot peening using a non-ferrous shot material.   The drive shaft member has a large diameter portion that contacts the inner end side surface of the hub, and the lubricating coating is formed on at least one contact surface of the large diameter portion and the inner end side surface of the hub. The hub unit bearing for a drive wheel according to claim 1, wherein the hub unit bearing is for a drive wheel.   The inner member has an inner ring that is fitted on the hub, and the drive shaft member has a large-diameter portion that abuts against the inner end side surface of the inner ring, and the large-diameter portion and the inner end side of the inner ring The drive wheel hub unit bearing according to claim 1, wherein the lubricating coating is formed on at least one of the side surfaces.   The hub unit bearing for a drive wheel according to any one of claims 1 to 3, wherein the lubricating coating is formed on a member of the inner member that contacts the drive shaft member.

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