JP2019052669A - Hub unit bearing for drive wheel - Google Patents

Abstract

To provide a hub unit bearing for drive wheel capable of preventing generation of noise called as stick slip sound.SOLUTION: In a hub unit bearing for drive wheel, a hub ring is connected and fixed to a constant velocity joint by fastening a nut screwed into a tip part of a spline shaft, in a state of contacting an axial inner end surface of an inner ring with an axial outer end surface of an outer ring for constant velocity joint of the constant velocity joint. At an axial inner end of the inner ring, an inner diameter extension part is provided so as to extend to an inner diameter side with respect to an outer diameter surface of a small diameter stage part, and the axial outer end surface of the outer ring for constant velocity joint contacts with the axial inner end surface of the inner diameter extension part.SELECTED DRAWING: Figure 1

Description

  The present invention is an assembly in which a constant velocity joint is integrally assembled with a hub unit bearing, and is used to rotatably support a driving wheel of an automobile with respect to a suspension device and to rotationally drive the driving wheel. The present invention relates to a hub unit bearing for a drive wheel.

  Various hub unit bearings are used to rotatably support automobile wheels with respect to a suspension system. The hub unit bearing for the drive wheel for supporting the drive wheel on the suspension device and rotating the drive wheel is a combination of the constant velocity joint and the hub unit bearing, the relative displacement between the differential gear and the drive wheel, and the wheel. It is necessary to smoothly transmit the rotation of the drive shaft to the wheels regardless of the steering angle given to the wheel. FIG. 4 shows a drive wheel hub unit bearing described in Patent Document 1 as an example of a conventional structure.

  The drive wheel hub unit bearing 1 includes an outer ring 2 and a hub ring 3, and a plurality of rolling elements 6. A double row outer ring raceway 8 is provided on the inner peripheral surface of the outer ring 2, and a double row inner ring raceway 10 is provided on the outer peripheral surface of the hub ring 3. A rolling element 6 is rotatably arranged between each outer ring raceway 8 and each inner ring raceway 10, and the hub ring 3 is rotatably supported on the inner diameter side of the outer ring 2.

The hub wheel 3 is configured by combining a hub body 4 and an inner ring 5. The hub body 4 is provided with a hub flange 9 for supporting a wheel on the outer side in the axial direction of the outer peripheral surface, and a small diameter step portion 11 is formed at the inner end in the axial direction of the outer peripheral surface. The inner ring 5 is externally fixed to the outer peripheral surface of the small diameter step portion 11. A spline hole 12 is provided in the center of the hub body 4.
Note that “outside in the axial direction” means the outer side in the width direction of the vehicle in the assembled state in the automobile and the left side in each figure. On the other hand, the inner side in the axial direction is the side that is the central side in the width direction of the vehicle, and is the right side of each figure.

  The constant velocity joint 20 includes a constant velocity joint outer ring 21 and a spline shaft 22. A spline shaft 22 provided on the outer end surface in the axial direction of the outer ring 21 for the constant velocity joint is engaged with the spline hole 12 of the hub body 4. Specifically, the spline shaft 22 is inserted into the spline hole 12 of the hub body 4 (hub wheel 3) from the inside in the axial direction, and the outer ring 21 of the constant velocity joint outer ring 21 is axially outside the inner end surface of the inner ring 5 in the axial direction. Contact the end face. In this state, the hub wheel 3 and the constant velocity joint 20 are coupled and fixed to each other by screwing a nut 24 to a male screw provided at the outer end of the spline shaft 22 in the axial direction.

The driving wheel hub unit bearing as shown in FIG. 4 sometimes generates unusual noise called stick-slip noise during operation. The occurrence of such abnormal noise is based on the fluctuation of torque transmitted between the constant velocity joint 20 and the drive wheel hub unit bearing 1, and the axial direction inner end face of the inner ring 5 and the axial direction of the constant velocity joint outer ring 21. It is known that the cause is that the contact portion 25 with the outer end surface rubs. That is, the torque changes as the automobile accelerates and decelerates, but the spline shaft 22 of the constant velocity joint 20 is elastically deformed in the torsional direction along with the torque transmission, and the amount of deformation varies with the fluctuation of the torque. Change.
When the force for deforming the spline shaft 22 in the torsional direction or the force for returning the torsionally deformed spline shaft 22 becomes larger than the frictional force acting on the contact portion 25, the contact portion At 25, a minute slip (stick slip) occurs. If the frictional force acting on the contact portion 25 is large, the energy for rubbing the axial inner end surface of the inner ring 5 and the axial outer end surface of the outer ring 21 for the constant velocity joint based on slippage increases, and an annoying noise (stick (Slip noise) occurs.

  In order to reduce the energy of friction at the contact portion 25, it is conceivable to reduce the tightening force of the nut 24 and lower the surface pressure of the contact portion 25. In the case of the conventional structure shown in FIG. Since the preload is applied to each rolling element 6 based on the tightening force of the nut 24 and the inner ring 5 is prevented from creeping, it is difficult to reduce the tightening force of the nut 24.

JP 2005-180688 A

  In view of such circumstances, it is an object of the present invention to provide a hub unit bearing for a drive wheel that prevents generation of abnormal noise called stick-slip noise.

  A hub unit bearing for a drive wheel according to the present invention includes an outer ring having a double row outer ring raceway on an inner peripheral surface, a hub wheel having a double row inner ring raceway on an outer peripheral surface, and the outer ring raceway and the inner ring raceway. A plurality of rolling elements arranged, and the hub wheel is externally fitted and fixed to a hub body having a hub flange for wheel mounting, and a small-diameter step formed at an axially inner end of the hub body. The hub body is rotationally driven by engaging a spline shaft of a constant velocity joint with a spline hole provided in the center, and the hub wheel constitutes the constant velocity joint. The constant velocity joint is fixedly coupled to the constant velocity joint by tightening a nut screwed to the tip end portion of the spline shaft while the axial inner end surface of the inner ring is in contact with the outer circumferential surface of the outer ring for the constant velocity joint. ing.

In particular, the drive wheel hub unit bearing of the present invention is provided with an inner diameter expansion portion extending on the inner diameter side of the outer diameter of the small diameter step portion at the inner end in the axial direction of the inner ring, and the axial direction of the inner diameter expansion portion. The outer end surface in the axial direction of the outer ring for constant velocity joint is in contact with the inner end surface.
Furthermore, the inner diameter of the inner ring and the outer diameter of the small diameter step portion are spline-fitted.
Furthermore, the outer diameter size of the contact portion between the inner end surface in the axial direction of the inner ring and the outer end surface in the axial direction of the outer ring for the constant velocity joint is smaller than the outer diameter size of the small diameter step portion.

  ADVANTAGE OF THE INVENTION According to this invention, the hub unit bearing for drive wheels which prevented generation | occurrence | production of the unusual sound called stick-slip sound can be provided.

Sectional drawing of the hub unit bearing for drive wheels which shows 1st Embodiment. Sectional drawing of the hub unit bearing for drive wheels which shows 2nd Embodiment. Sectional drawing of the hub unit bearing for drive wheels which shows 3rd Embodiment. Sectional drawing of the hub unit bearing for drive wheels which shows an example of the conventional structure.

[First Embodiment]
FIG. 1 shows a hub unit bearing for a drive wheel according to a first embodiment of the present invention. The hub unit bearing 1a for a drive wheel according to this embodiment includes an outer ring 2a, a hub ring 3a, and a plurality of rolling elements 6.
The outer ring 2a is coupled and fixed to a knuckle (not shown) constituting the suspension device by a mounting flange 7 formed on the outer peripheral surface. Double row outer ring raceways 8 are provided on the inner peripheral surface of the outer ring 2a.
The hub ring 3a is provided with double-row inner ring raceways 10 on the outer peripheral surface. By disposing a plurality of rolling elements 6 between each outer ring raceway 8 and each inner ring raceway 10 so as to roll freely, the hub ring 3a is rotatably supported concentrically with the outer ring 2a on the inner diameter side of the outer ring 2a. ing.

  The hub wheel 3a is configured by combining a hub body 4a and an inner ring 5a. The hub body 4a is provided with a hub flange 9 for supporting the wheel on the outer side in the axial direction of the outer peripheral surface. Hub bolts 14 for attaching the wheels constituting the wheels are fixed to a plurality of locations at equal intervals in the circumferential direction of the hub flange 9. On the outer peripheral surface of the hub body 4a, an inner ring raceway 10 on the outer side in the axial direction is formed at an axially intermediate portion, and a small diameter step portion 11a is formed at the inner end in the axial direction. A spline hole 12 that penetrates the hub body 4a in the axial direction is provided at the center of the hub body 4a.

The inner ring 5a forms an inner ring raceway 10 on the outer circumferential surface on the inner side in the axial direction. An inner diameter expanding portion 15 extending toward the inner diameter side is formed on the inner end portion in the axial direction of the inner ring 5a over the entire circumference, and the cross-sectional shape of the inner ring 5a is substantially T-shaped. The inner end surface in the axial direction of the inner ring 5a is formed in an annular flat surface except for the chamfered portion.
In such an inner ring 5a, the inner diameter fitting portion 16 having a cylindrical surface is connected to the outer periphery of the small diameter step portion 11a while the outer end surface in the axial direction is in contact with the step surface on the outer side in the axial direction of the small diameter step portion 11a. It is fixed on the surface. There is an axial gap between the axially outer side surface of the inner diameter expansion portion 15 and the axial inner end surface of the hub body 4a (small diameter step portion 11a), and the inner diameter expansion portion 15 contacts the hub body 4a. Not done.

  Between the inner peripheral surface of the outer ring 2a and the outer peripheral surface of the hub ring 3a, the bearing internal space in which the rolling elements 6 are arranged has its axially open ends sealed by sealing devices 13a and 13b, respectively. Yes. The sealing devices 13a and 13b prevent the grease sealed in the bearing internal space from leaking to the external space and prevent dust and the like existing in the external space from entering the bearing internal space.

  The constant velocity joint 20 includes a constant velocity joint outer ring 21 and a spline shaft 22. The spline shaft 22 is provided at the center of the axial outer end face of the constant velocity joint outer ring 21 and is freely engageable with the spline hole 12 of the hub wheel 4a. A male screw portion 23 into which a nut 24 described later is assembled is formed at the axially outer end portion of the spline shaft 22.

  When the constant velocity joint 20 and the drive wheel hub unit bearing 1a are coupled and fixed to each other, the spline shaft 22 is inserted into the spline hole 12 from the inner side in the axial direction. Then, a nut 24 is screwed into the male thread portion 23 of the spline shaft 22 protruding from the outer surface in the axial direction of the hub wheel 4a, and further tightened. In this state, the inner end surface in the axial direction of the inner ring 5a fitted to the small diameter step portion 11a is in contact with the outer end surface in the axial direction of the outer ring 21 for constant velocity joint. The abutting surface of the inner ring 5a and the abutting surface of the constant velocity joint outer ring 21 are both flat annular surfaces and form an abutting portion 25a. The contact surface of the inner ring 5a includes an inner diameter expanding portion 15, and the inner end surface in the axial direction of the inner diameter expanding portion 15 is in contact with the outer end surface (contact surface) in the axial direction of the outer ring for the constant velocity joint. An appropriate preload is applied to each rolling element 6 by holding the hub main body 4a and the inner ring 5a by the nut 24 and the outer ring 21 for constant velocity joint.

Since the contact surface (the inner end surface in the axial direction) of the inner ring 5a constituting the contact portion 25a is enlarged toward the inner diameter side by the inner diameter expanding portion 15, the area of the contact portion 25a can be increased. Therefore, the surface pressure acting on the contact portion 25a between the contact surface (axial inner end surface) of the inner ring 5a and the axial outer end surface of the constant velocity joint outer ring 21 due to the tightening force (tightening torque) of the nut 24 is reduced. The average value can be kept low.
In order to prevent deformation of the inner ring raceway 10 formed on the inner ring 5a, the outer diameter of the contact portion 25a is restricted to be equal to or less than the raceway diameter (groove bottom diameter) of the inner ring raceway 10.

With the configuration as described above, the drive wheel hub unit bearing 1a of the present embodiment can prevent the generation of abnormal noise called stick-slip noise.
That is, since the surface pressure of the abutting portion 25a is kept low, both end surfaces (the inner end surface in the axial direction of the inner ring 5a and the outer end surface in the axial direction of the outer ring 21 for the constant velocity joint) accompany the torsional deformation of the spline shaft 22 during operation. ) Even if they are in a state of rubbing each other, the energy for rubbing both end surfaces is small (both end surfaces rub with each other when the torsional deformation is small), and an abnormal noise called stick-slip noise is not generated on the contact surface 25a. Can be kept low enough not to be harsh.

[Second Embodiment]
FIG. 2 shows a drive wheel hub unit bearing according to a second embodiment of the present invention. In the drive wheel hub unit bearing 1b of the present embodiment, the male spline portion 17 is formed in the small diameter step portion 11b of the hub body 4b, and the female spline portion 18 is formed in the fitting inner diameter portion 16a of the inner ring 5b. And the female spline part 18 of the inner ring | wheel 5b is inserted from the axial direction inner side with respect to the male spline part 17 of the small diameter step part 11b, and it is made to spline-fit.
The abutting portion 25a is configured by abutting the axially outer end surface of the outer ring 21 for the constant velocity joint with the axially inner end surface of the inner ring 5b including the inner diameter expanding portion 15.

  The axial dimension of the small-diameter step portion 11b and the axial dimension of the fitting inner diameter portion 16a are made shorter than those in the first embodiment, and the step surface on the axially outer side of the small-diameter step portion 11b is formed on the double-row inner ring raceway 10. It is formed at a position almost in the middle. The small-diameter step portion 11b has a configuration in which the small-diameter step portion 11b does not overlap in the radial direction with respect to the spline fitting portion between the spline hole 12 and the spline shaft 22 (is separated in the axial direction). It is prevented from being deformed by torque.

  In the case of a hub unit bearing for a drive wheel, it is necessary to insert a spline shaft 22 as a drive shaft through the spline hole 12 formed in the center, and the hub wheel 3b becomes relatively thin. Accordingly, creep is likely to occur between the inner ring and the small-diameter step portion of the hub body due to the torsional deformation of the spline shaft 22. In the case of this embodiment, since the fitting width (dimension in the axial direction) between the fitting inner diameter portion 16a and the small diameter step portion 11b of the inner ring 5b is small, the creep is more likely to occur, but the female spline portion 18 of the inner ring 5b. And the male spline portion 17 of the small-diameter step portion 11b are spline-fitted to prevent the creep from occurring.

In the first embodiment described above, the axial dimension of the small-diameter step portion 11a (see FIG. 1) is increased, and a part of the small-diameter step portion 11a extends to a position where it overlaps the rolling element 6 on the outer side in the axial direction. doing. In this way, the inner ring 5a and the small-diameter step portion 11a are fitted to each other so that creeping between the inner ring 5a and the hub main body 4a can be easily prevented. If splines are fitted, creep can be safely prevented.
Other configurations and operational effects are the same as those of the first embodiment described above.

[Third Embodiment]
FIG. 3 shows a hub unit bearing for a drive wheel according to a third embodiment of the present invention. In the drive wheel hub unit bearing 1c according to the present embodiment, the outer diameter of the contact portion 25b where the axial inner end surface of the inner ring 5c and the axial outer end surface of the constant velocity joint outer ring 21a are in contact is restricted. Specifically, the outer diameter dimension of the contact portion 25b is smaller than the outer diameter dimension of the small-diameter step portion 11a, and the constant velocity joint outer ring 21a is in contact with only the inner diameter expansion portion 15a of the outer ring 5c. Yes.

The outer ring 21a for the constant velocity joint extends to the inner diameter side of the inner ring 5c and is in contact with the inner end surface (contact part 25b) in the axial direction of the inner diameter expansion part 15a having low rigidity. As a state where slip is more likely to occur, a large stick slip accompanied by a stick slip sound is prevented from occurring (sliding is performed with a small torsional deformation).
In the present embodiment, the area of the contact portion 25b is increased to reduce the surface pressure by reducing the chamfer dimension formed in the axially inner diameter portion (the inner diameter portion of the contact surface) of the inner diameter expansion portion 15a. Keep it low.
The configuration of this embodiment can be combined with the second embodiment described above. Other configurations and operational effects are the same as those of the first embodiment described above.

The hub unit bearing for a drive wheel of the present invention can be suitably used as a hub unit bearing used to rotatably support a drive wheel of an automobile with respect to a suspension device and to drive the drive wheel to rotate.

1, 1a to 1c Drive wheel hub unit bearing 2, 2a Outer ring 3, 3a Hub 4, 4a Hub body 5, 5a to 5c Inner ring 6 Ball 7 Stationary flange 8 Outer ring raceway 9 Rotating flange 10 Inner ring raceway 11, 11a, 11b Small diameter Step portion 12 Spline holes 13a, 13b Sealing device 14 Hub bolts 15, 15a Inner diameter expansion portions 16, 16a Fitting inner diameter portion 17 Male spline portion 18 Female spline portion 20 Constant velocity joint 21, 21a Constant velocity joint outer ring 22 Spline shaft 23 Male thread Part 24 nut 25 contact part

Claims (3)

An outer ring having a double row outer ring raceway on the inner peripheral surface, a hub wheel having a double row inner ring raceway on the outer peripheral surface, and a plurality of rolling elements disposed between the outer ring raceway and the inner ring raceway. ,
The hub wheel is composed of a hub body having a hub flange for wheel mounting, and an inner ring that is externally fitted and fixed to a small-diameter step portion formed at an axially inner end of the hub body.
The hub body is rotationally driven by engaging a spline shaft of a constant velocity joint with a spline hole provided in the center,
A nut threadedly engaged with the tip end portion of the spline shaft in a state in which the hub wheel is in contact with the axially inner end surface of the inner ring on the axially outer end surface of the constant velocity joint outer ring constituting the constant velocity joint. A hub unit bearing for a driving wheel that is coupled and fixed to the constant velocity joint by tightening,
An inner diameter expansion portion extending toward the inner diameter side of the outer diameter of the small diameter step portion is provided at the inner end in the axial direction of the inner ring, and the axial outer end of the constant velocity joint outer ring is disposed on the inner end surface in the axial direction of the inner diameter expansion portion. A hub unit bearing for a drive wheel, characterized in that the end faces are in contact.   The drive wheel hub unit bearing according to claim 1, wherein an inner diameter of the inner ring and an outer diameter of the small diameter step portion are spline-fitted. The outer diameter size of the contact portion between the inner end surface in the axial direction of the inner ring and the outer end surface in the axial direction of the outer ring for the constant velocity joint is smaller than the outer diameter size of the small diameter step portion. The hub unit bearing for drive wheels of 2.

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