JP2013238266A - Rolling bearing for wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing for a wheel capable of suppressing fretting wear, even when supporting wheels of a vehicle in a stop condition under vibration environment.SOLUTION: A rolling bearing device 1 for a wheel has an inner shaft, an outer wheel, and a plurality of truncated conical rollers interposed between an inner shaft raceway surface and an outer wheel raceway surface rollably under grease lubrication. The shape of the contour P of a cross section perpendicular to an axis of the outer wheel race way surface extending along a vehicle horizontal direction and formed to a shape capable of lowering a contacting face pressure between the outer wheel raceway surface and truncated taper rollers in intersecting parts K1, K2 where a radial directional virtual line D1 passing a shaft center O intersect with the outer wheel raceway surface more than in the case the contour shape is a perfect circle by setting an inner diameter dimension d1 of the outer wheel raceway surface along the vehicle horizontal direction when the outer wheel raceway surface is fixed to a vehicle larger than an inner diameter dimension d2 of the outer wheel raceway surface along a vehicle vertical direction when the outer wheel is fixed to the vehicle.

Description

  The present invention relates to a wheel rolling bearing for supporting a wheel of an automobile, for example.

  Wheel rolling bearings are used in vehicles such as automobiles to support the wheels (see, for example, Patent Document 1).

JP 2004-116715 A

An automobile or the like to which the wheel rolling bearing is attached may be transported by freight car as a transportation method for sale.
In freight car transport, vibrations that occur during freight car travel propagate to the cars in the freight car. For this reason, the said vibration propagates also to the rolling bearing for wheels attached to the motor vehicle, and the said rolling bearing for wheels supports a wheel in the stop state in the environment where it vibrates.

The vibration during traveling of the freight car sometimes causes fretting wear on the wheel rolling bearing that supports the wheel.
In a fretting wear test conducted assuming a wheel rolling bearing that supports a vehicle wheel in a stopped state, fretting wear occurs at the intersection of the outer ring raceway surface where the radial imaginary line along the vehicle horizontal direction intersects. Often occurs.
When such fretting wear occurs during transportation of the automobile, the life performance of the wheel rolling bearing is reduced regardless of the travel distance of the automobile.

  The present invention has been made in view of such circumstances, and provides a wheel rolling bearing capable of suppressing fretting wear even when supporting a vehicle wheel that is stopped in a vibration environment. For the purpose.

  The present inventor has conducted extensive research based on the fact that fretting wear occurs at the intersection where the radial imaginary lines along the horizontal direction of the vehicle intersect on the outer ring raceway surface, and as a result, the load load around the intersection is compared. Therefore, the inventors have obtained knowledge that fretting wear is likely to occur because the degree of freedom of movement of the rolling elements is moderate, and the present invention has been completed based on this knowledge.

  That is, the present invention for achieving the above object is a wheel rolling bearing attached to a vehicle and supporting a wheel, and an inner ring member to which the wheel is attached at one end in an axial direction, and fixed to the vehicle. And an outer ring member disposed concentrically on the outer peripheral side of the inner ring member, an inner ring raceway surface formed on the outer peripheral side of the inner ring member, and an outer ring raceway surface formed on the inner peripheral side of the outer ring member. A plurality of rolling elements that are freely rollable under grease lubrication, and the contour shape of the outer ring raceway surface in a cross section orthogonal to the axis is a vehicle horizontal direction when the outer ring is fixed to the vehicle Is set to be larger than the inner diameter dimension of the outer ring raceway surface along the vertical direction of the vehicle when the outer ring is fixed to the vehicle. axis A shape capable of lowering the contact surface pressure between the outer ring raceway surface and the rolling element at the intersection where a radial imaginary line passing through the center intersects the outer ring raceway surface as compared with the case where the contour shape is a perfect circle. It is characterized by being said.

  According to the wheel rolling bearing configured as described above, the contour shape of the outer ring raceway surface in a cross section orthogonal to the axis line is the cross-section where the radial virtual line along the vehicle horizontal direction intersects the outer ring raceway surface. Since the contact surface pressure between the outer ring raceway surface and the rolling element can be reduced as compared with the case where the contour shape is a perfect circle, the load load in the vehicle in a stopped state is greater than the vehicle vertical direction. It is possible to further reduce the contact surface pressure between the outer ring raceway surface around the low intersection and the rolling element. In the vicinity of the intersection, fretting wear is likely to occur because the load is relatively low and the degree of freedom of movement of the rolling elements is moderate. Therefore, as described above, the contact surface pressure around the intersection can be further reduced, and the degree of freedom of movement of the rolling elements can be further increased to promote the formation of an oil film of grease on the contact surface. It is possible to suppress fretting wear remarkably occurring between the outer ring raceway surface and the rolling elements around the intersection when the vehicle wheel in a stopped state is supported.

  In the wheel rolling bearing described above, it is preferable that the contour shape of the outer ring raceway surface is an elliptical shape whose major axis is along the horizontal direction of the vehicle. In this case, the vehicle left-right direction part can be smoothly connected from the vehicle vertical direction part in the outline shape.

  Further, in the rolling bearing for wheel, in a predetermined arc range including the intersecting portion in the contour shape of the outer ring raceway surface, with respect to a reference circle determined by an inner diameter dimension of the outer ring raceway surface along the vehicle vertical direction, It is preferable that a curved portion that is concavely curved toward the outside in the radial direction is formed, and in this case, the range and curvature of the curved portion can be adjusted as necessary.

  According to the rolling bearing for a wheel of the present invention, fretting wear can be suppressed even when a vehicle wheel that is stopped in a vibration environment is supported.

It is an axial sectional view of a rolling bearing device concerning one embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a diagram exaggeratingly showing the contour of the outer ring raceway surface in FIG. 2. It is a figure which shows the grinding | polishing method of the outer ring raceway surface of the outer ring of this embodiment. It is the figure which exaggerated and showed the outline of the outer ring raceway surface concerning other examples of the present invention.

  Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an axial sectional view of a rolling bearing device for a wheel according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. The wheel rolling bearing device 1 supports a wheel of an automobile or the like so as to be rotatable with respect to a suspension device.

The wheel rolling bearing device 1 includes an outer ring 2, an inner shaft 3 as an inner ring, a plurality of tapered rollers 4 as rolling elements arranged between the outer ring 2 and the inner shaft 3, and these tapered rollers 4 respectively. And a retainer 5 that holds the double-row tapered roller bearing.
The inner shaft 3 as an inner ring member constitutes an axle to which a wheel (not shown) is attached at the same time as a rotating wheel. An inner ring raceway surface 3 a on which the tapered rollers 4 roll is formed on the outer peripheral surface of the inner shaft 3. A flange portion 6 for fixing the wheel is formed at one end portion of the inner shaft 3.

  The outer ring 2 as an outer ring member is a fixed ring that is fixed to a suspension device (not shown) of an automobile, and is arranged concentrically on the outer peripheral side of the inner shaft 3. An outer ring raceway surface 2 a on which the tapered rollers 4 roll is formed on the inner peripheral surface of the outer ring 2. Further, a flange portion 7 for fixing to the automobile is formed on the outer peripheral surface of the outer ring 2. The flange portion 7 is formed in accordance with a vehicle-side fixing portion to which the wheel rolling bearing device 1 is fixed. When the outer ring 2 is fixed to the automobile, the outer ring 2 is fixed so that a specific position in the circumferential direction is upward. In FIG. 2, the wheel rolling bearing device 1 of the present embodiment is such that the vertical direction of the paper is the vertical direction of the automobile (vehicle vertical direction), and the horizontal direction of the paper is the horizontal direction of the automobile (horizontal direction of the vehicle). It shall be fixed.

The tapered roller 4 is interposed between the outer ring raceway surface 2a and the inner ring raceway surface 3a so as to roll freely under grease lubrication.
With the above configuration, the rolling bearing device 1 for a wheel supports a wheel attached to the automobile and fixed to the inner shaft 3 so as to be integrally rotatable with the automobile so as to be rotatable.

FIG. 3 is an exaggerated view of the contour of the outer ring raceway surface 2a in FIG. 3 shows the contour shape of the outer ring raceway surface 2a in a cross section perpendicular to the axis of the wheel rolling bearing device 1. As shown in FIG.
Also in FIG. 3, the vertical direction of the paper is the vehicle vertical direction when the outer ring 2 is fixed to the automobile, and the horizontal direction of the paper is the horizontal direction of the vehicle when the outer ring 2 is fixed to the automobile. In the drawing, the contour shape of the contour P of the outer ring raceway surface 2a is an ellipse whose major axis is along the vehicle horizontal direction.

  In the present embodiment, the difference between the inner diameter dimension d1 of the outer ring raceway surface 2a along the vehicle horizontal direction as the long axis and the inner diameter dimension d2 of the outer ring raceway surface 2a along the vehicle vertical direction as the minor axis is set to 40 μm. ing. Therefore, the roundness of the outer ring raceway surface 2a of the present embodiment is 20 μm.

The shaft diameter of the inner shaft 3 in a general wheel rolling bearing device 1 is 30 to 60 mm, and in this case, the allowable roundness of the outer ring raceway surface 2a is about 5 μm or less.
On the other hand, from the viewpoint of bearing life, a bearing that is inferior to the allowable value if the roundness of the outer ring raceway surface 2a in the above-described general wheel rolling bearing device 1 is in the range of 10 to 20 μm. It has been confirmed that the lifetime can be maintained.
That is, in the present embodiment, the inner diameter dimension d1 and the inner diameter dimension d2 are set so as to be in a numerical range exceeding the allowable range of roundness within a range in which the bearing life can be maintained.

  Here, the outer ring raceway surface 2a of the present embodiment sets the inner diameter dimensions d1 and d2 as described above, so that the first radial imaginary line D1 that passes along the axis O in FIG. The contact surface pressure between the outer ring raceway surface 2a and the tapered roller 4 at horizontal intersecting portions K1 and K2 intersecting the contour P of the outer ring raceway surface 2a is lower than when the contour shape of the outer ring raceway surface 2a is a perfect circle. Is set to Here, the case where the contour shape of the outer ring raceway surface 2a is a perfect circle is a case where the roundness of the outer ring raceway surface 2a is 5 μm or less, which is the allowable range.

  In other words, in the present embodiment, the contour shape of the outer ring raceway surface 2a in the cross section orthogonal to the axis line is such that the inner diameter dimension d1 along the vehicle horizontal direction is larger than the inner diameter dimension d2 along the vehicle vertical direction to the extent that it exceeds the range of the perfect circle. Is set to be larger, the outer ring raceway surface 2a and the tapered roller at the horizontal intersecting portions K1 and K2 where the first radial imaginary line D1 that passes along the vehicle center direction and passes through the axial center O intersects the outer ring raceway surface 2a. The contact surface pressure between the outer ring raceway surface 2a and the outer ring raceway surface 2a can be made lower than that when the contour shape of the outer ring raceway surface 2a is a perfect circle.

  For this reason, in the automobile in a stopped state, the load applied by the automobile is more than the vertical intersecting portions K3 and K4 where the second radial imaginary line D2 that passes along the axial center O along the vehicle vertical direction intersects the outer ring raceway surface 2a. The contact surface pressure between the outer ring raceway surface 2a around the horizontal crossing portions K1 and K2 and the tapered rollers 4 can be further reduced. Since the load is relatively low and the degree of freedom with respect to the movement of the tapered roller 4 is moderate in the vicinity of the horizontal intersecting portions K1, K2, fretting wear tends to occur. Therefore, as described above, the contact surface pressure around the horizontal crossing portions K1, K2 can be further reduced, and the degree of freedom of movement of the tapered roller 4 can be further increased to promote the formation of an oil film of grease on the contact surface. Fretting wear significantly generated between the outer ring raceway surface 2a around the horizontal crossing portions K1 and K2 and the tapered rollers 4 when supporting the wheels of the automobile that is stopped in a vibration environment can be suppressed. .

  In the above embodiment, since the contour shape of the outer ring raceway surface 2a is an elliptical shape, even if the inner diameter dimension d1 is set larger than the inner diameter dimension d2 so that the contour shape exceeds the range of the perfect circle, The vehicle left-right direction part can be smoothly connected from the vehicle vertical direction part in an outline shape.

In the above-described embodiment, the difference between the inner diameter dimension d1 and the inner diameter dimension d2 is set to 40 μm, but the allowable range of roundness where the contour shape of the outer ring raceway surface 2a is a perfect circle is 5 μm or less. Therefore, if the difference between the inner diameter dimension d1 and the inner diameter dimension d2 is set to be larger than 10 μm, a contour shape exceeding the range of the perfect circle can be obtained. Therefore, the difference between the inner diameter dimension d1 and the inner diameter dimension d2 is preferably larger than 10 μm.
In addition, as described above, the upper limit value of the difference between the inner diameter dimension d1 and the inner diameter dimension d2 is preferably 40 μm or less from the viewpoint of bearing life.

FIG. 4 is a diagram showing a polishing method for the outer ring raceway surface 2a of the outer ring 2 of the present embodiment. Since the outer ring raceway surface 2a needs to set the inner diameter dimension d1 along the first radial direction imaginary line D1 larger than the inner diameter dimension d2, when polishing the outer ring raceway surface 2a, as shown in FIG. The outer ring outer peripheral surface corresponding to the horizontal crossing portions K1 and K2 (FIG. 3) is pressed by the pressing jig 10 toward the inner peripheral direction.
Thereby, the outer ring 2 can be elastically deformed, and the polishing allowance of the inner peripheral portion of the portion pressed by the pressing jig 10 can be made larger than that of the other portions.

As described above, the cylindrical polishing grindstone 11 is inserted into the inner peripheral side of the outer ring 2 pressed by the pressing jig 10 to polish the outer ring raceway surface 2a, and the outer ring raceway is pressed with the outer ring 2 pressed. Polishing is performed so that the surface 2a is substantially circular.
Thereafter, if the pressing by the pressing jig 10 is released, the outer ring 2 is elastically restored, and the inner peripheral portion of the portion pressed by the pressing jig 10 is polished to a larger extent than the other portions, and the outer ring raceway surface The inner diameter dimension of the portion corresponding to the horizontal crossing portions K1 and K2 in 2a can be made larger than that of the other portions.
The difference between the inner diameter dimension d1 and the inner diameter dimension d2 can be adjusted by adjusting the pressing pressure of the pressing jig 10.

  The present invention is not limited to the above embodiments. In the above embodiment, the case where the contour shape of the outer ring raceway surface 2a is an ellipse is illustrated, but for example, as shown in FIG. 5, the horizontal crossing portions K1 and K2 are positioned on the contour P of the outer ring raceway surface 2a. A curved portion 20 is formed in a predetermined arc range S to be concaved toward the outer side in the radial direction with respect to a reference circle T determined by the inner diameter dimension d2, and the inner diameter dimension d1 is set larger than the inner diameter dimension d2. May be. The reference circle T is a circle that passes through the vertical crossing portions K3 and K4. In this case, the range and curvature of the curved portion can be adjusted as necessary while the inner diameter dimension d1 is set larger than the inner diameter dimension d2.

  Moreover, in the said embodiment, although the case where this invention was applied to the rolling bearing apparatus 1 for wheels using a tapered roller bearing was illustrated, this invention is not restricted to a tapered roller bearing, The wheel using an angular ball bearing. The present invention can also be applied to a rolling bearing device for use.

1 Rolling bearing device for wheels 2 Outer ring (outer ring member)
2a Outer ring raceway surface 3 Inner shaft (inner ring member)
3a Inner ring raceway surface 4 Tapered rollers (rolling elements)
20 Curved portion d1 Inner diameter d2 Inner diameter D1 First radial imaginary line K1, K2 Horizontally intersecting portion

Claims (3)

A wheel rolling bearing attached to a vehicle and supporting a wheel,
An inner ring member to which the wheel is attached to one end in the axial direction;
An outer ring member fixed to the vehicle and disposed concentrically on the outer peripheral side of the inner ring member;
A plurality of rolling elements interposed between the inner ring raceway surface formed on the outer peripheral side of the inner ring member and the outer ring raceway surface formed on the inner peripheral side of the outer ring member so as to roll freely under grease lubrication; With
The contour shape of the outer ring raceway surface in the cross section perpendicular to the axis is
The inner diameter dimension of the outer ring raceway surface along the vehicle horizontal direction when the outer ring is fixed to the vehicle is larger than the inner diameter dimension of the outer ring raceway surface along the vehicle vertical direction when the outer ring is fixed to the vehicle. By setting it large, the contact surface pressure between the outer ring raceway surface and the rolling element at the intersection where the radial imaginary line that passes along the vehicle horizontal direction and passes through the axial center intersects the outer ring raceway surface is reduced. The wheel rolling bearing according to claim 1, wherein the contour shape is a shape that can be lowered as compared with a perfect circle.   2. The wheel rolling bearing according to claim 1, wherein a contour shape of the outer ring raceway surface is an elliptical shape whose major axis is along the horizontal direction of the vehicle.   The predetermined circular arc range including the intersecting portion in the contour shape of the outer ring raceway surface has a concave curved shape toward the outer side in the radial direction with respect to a reference circle determined by the inner diameter dimension of the outer ring raceway surface along the vehicle vertical direction. The wheel rolling bearing according to claim 1, wherein a curved portion that is recessed is formed.

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