JP2021143750A - Wheel bearing device - Google Patents

Abstract

To provide a wheel bearing device capable of improving strength of an inner member while suppressing increase of costs.SOLUTION: A wheel bearing device 1 includes an inner member 2 having a wheel mounting flange 22, an outer member 3, and a plurality of first and second rolling elements 4, 5. The first rolling element 4 at a side of the wheel mounting flange 22 is a conical roller having a large-diameter portion 41 at an axial one end portion, and a small-diameter portion 42 at the axial other end portion. The inner member 2 has an annular collar portion 23 with a collar surface 23a opposed to the large-diameter portion 41. On an axial cross-section of the inner member 2, a corner portion R between a first inner raceway surface 2a and the collar surface 23a is formed so as not to project to a radial inner side with respect to an extension line L of the first inner raceway surface 2a extended to the side of the wheel mounting flange 22. The conical roller 4 has an annular recessed portion 410 recessed toward the small-diameter portion 42 side, on an outer edge of the large-diameter portion 41, and a projecting portion 411 formed inside of the recessed portion 410 is slidably kept into contact with the collar surface 23a.SELECTED DRAWING: Figure 2

Description

The present invention relates to a wheel bearing device.

Conventionally, a wheel bearing device that supports a wheel with respect to a vehicle body has a cylindrical outer member attached to a knuckle of a suspension device, an inner member having a wheel mounting flange to which the wheel is attached, and an outer member. It is provided with a plurality of rolling elements arranged between the wheel and the inner member. Spherical rolling elements are often used for wheel bearing devices for small vehicles, but rolling elements are used for wheel bearing devices used for vehicles with a large body weight such as pickup trucks and vans, for example. As a result, a partial cone-shaped conical roller is often used.

In the inner member of the wheel bearing device in which such a conical roller is used, a tapered inner raceway surface on which the conical roller rolls and a brim surface facing the large diameter portion of the conical roller are formed by a grindstone. It is formed by grinding. At the corner between the inner raceway surface and the brim surface, a notch-shaped hollow portion extending in the circumferential direction is turned to allow the peripheral edge of the grindstone to escape during grinding and to avoid interference with the corner of the conical roller. Is formed by. However, when such a stiffened portion is formed, there is a problem that stress tends to be concentrated around the stiffened portion due to the bending load applied to the wheel mounting flange.

In the wheel bearing device described in Patent Document 1, the durability of the inner member is enhanced by subjecting the surface layer of the dull portion to a surface treatment by laser peening that applies compressive residual stress.

JP-A-2018-162817

As described in Patent Document 1, if the surface layer of the dull portion is surface-treated by laser peening to apply compressive residual stress, the durability of the inner member can be improved, but for example, when the wheel rides on the edge stone. For a large impact load generated in the above, the effect of increasing the strength of the streaked portion by applying the compressive residual stress may not be fully exhibited. In addition, the man-hours for performing laser peening increase, and the cost increases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel bearing device capable of increasing the strength of an inner member while suppressing an increase in cost.

In order to achieve the above object, the present invention comprises an inner member having a wheel mounting flange on which wheels are mounted, while the first and second inner raceway surfaces are formed in a double row so as to be arranged in the axial direction on the outer periphery. An outer member having first and second outer raceway surfaces facing the first and second inner raceway surfaces on the inner circumference, and the first inner raceway surface and the first outer raceway surface. The inner member includes a plurality of first rolling elements that roll on the second inner raceway surface and a plurality of second rolling elements that roll on the second inner raceway surface and the second outer raceway surface, and the inner member is the outer side. A wheel bearing device that rotates about a rotation axis with respect to a square member, wherein the first inner raceway surface is formed on the wheel mounting flange side with respect to the second inner raceway surface. The rolling element 1 is a conical roller having a large diameter portion at one end in the axial direction on the wheel mounting flange side and a small diameter portion at the other end in the axial direction, and the inner member is the large diameter portion of the conical roller. It has an annular brim portion on which a brim surface facing the diameter portion is formed, and a corner portion between the first inner raceway surface and the brim surface in an axial cross section along the rotation axis is the first. The inner raceway surface of the wheel is formed so as not to protrude inward in the radial direction from the extension line extending toward the wheel mounting flange side, and the conical roller is directed toward the small diameter portion on the outer edge of the large diameter portion. Provided is a wheel bearing device having a recessed annular recess and having a convex portion formed inside the recess in sliding contact with the flange surface.

According to the wheel bearing device according to the present invention, it is possible to increase the strength of the inner member while suppressing an increase in cost.

It is sectional drawing which shows the whole structure of the bearing device for a wheel which concerns on embodiment of this invention. FIG. 5 is an enlarged view showing an enlarged view of the first rolling element and its peripheral portion in FIG. 1. It is a perspective view which shows the 1st rolling element (conical roller). It is explanatory drawing which shows the grindstone which grinds the inner raceway surface and the brim surface together with the cross section of the peripheral part of the brim part. It is sectional drawing which shows a part of the bearing device for a wheel which concerns on 2nd Embodiment. It is a perspective view which shows the conical roller which concerns on 2nd Embodiment.

[First Embodiment]
Embodiments of the present invention will be described with reference to FIGS. 1 to 4. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect.

(Overall configuration of bearing device for wheels)
FIG. 1 is a cross-sectional view showing an overall configuration of a wheel bearing device according to an embodiment of the present invention. In FIG. 1, a wheel bearing device mounted on a vehicle is shown together with its peripheral portion.

The wheel bearing device 1 rotatably supports the wheels 9 together with the brake rotor 8 with respect to the knuckle 71 constituting the vehicle suspension device. FIG. 1 shows a part of the wheel 91 of the wheel 9 and the brake rotor 8. Hereinafter, in the wheel bearing device 1, the side on which the wheel 9 is attached (left side in FIG. 1) is referred to as the vehicle outer side, and the opposite side (right side in FIG. 1) is referred to as the vehicle inner side.

The wheel bearing device 1 is located between an inner member 2 composed of a hub 20 and an inner ring 200, an outer member 3 fixed to a knuckle 71 which is a vehicle body side member, and an inner member 2 and an outer member 3. A plurality of first rolling elements 4 and a plurality of second rolling elements 5 arranged in a plurality of rows, and a first cage 61 and a plurality of second rolling elements holding the plurality of first rolling elements 4. Seal rings 63, 64 on the outer side and inner side of the vehicle that prevent foreign matter from entering the bearing internal space 10 between the second cage 62 that holds the 5 and the inner member 2 and the outer member 3. And have. Grease (not shown) is sealed in the bearing internal space 10. The inner member 2 rotates about the rotation axis O with respect to the outer member 3. In FIG. 1, the wheel bearing device 1 is shown in an axial cross section along the rotation axis O.

On the outer circumference of the inner member 2, the first and second inner raceway surfaces 2a and 2b are formed in a double row so as to be arranged in the axial direction. The first inner raceway surface 2a is formed on the vehicle outer side (wheel mounting flange 22 side, which will be described later) with respect to the second inner raceway surface 2b. The outer member 3 integrally includes a cylindrical main body portion 31, a vehicle body mounting flange 32 attached to the knuckle 71 by a plurality of knuckle bolts 711, and eaves portions 33 and 34 to which the seal rings 63 and 64 are attached, respectively. doing. On the inner circumference of the main body 31, a first outer raceway surface 3a facing the first inner raceway surface 2a in the radial direction and a second outer raceway surface 3b facing the second inner raceway surface 2b in the radial direction are provided. It is formed. The first rolling element 4 rolls on the first inner raceway surface 2a and the first outer raceway surface 3a. The second rolling element 5 rolls on the second inner raceway surface 2b and the second outer raceway surface 3b.

The hub 20 integrally has a body portion 21 arranged inside the outer member 3 and a wheel mounting flange 22 for fixing the wheels 9 and the brake rotor 8 so that they cannot rotate relative to each other. The body portion 21 is composed of a large diameter portion 211 and a small diameter portion 212 having different outer diameters, and the large diameter portion 211 is provided on the vehicle outer side of the small diameter portion 212. A first inner raceway surface 2a is formed on the outer peripheral surface of the large diameter portion 211. An inner ring 200 is fitted on the outer peripheral surface of the small diameter portion 212. A second inner raceway surface 2b is formed on the outer peripheral surface of the inner ring 200. In the present embodiment, the inner member 2 has one inner ring 200, but the inner member 2 has two inner rings, and one of the inner rings has a first inner ring. The inner raceway surface 2a may be formed, and the second inner raceway surface 2b may be formed on the other inner ring.

The wheel mounting flange 22 projects radially outward from the body portion 21 on the vehicle outer side of the outer member 3. The wheel mounting flange 22 is provided with a plurality of through holes 220 into which a plurality of hub bolts 11 are press-fitted. The hub bolt 11 has a head portion 111 and a shaft portion 112, and a hub nut 12 is screwed onto the tip end portion of the shaft portion 112. The wheel 91 of the wheel 9 is provided with an insertion hole 910 through which the shaft portion 112 of the hub bolt 11 is inserted, and the wheel 9 is fixed to the wheel mounting flange 22 by screwing the hub nut 12 into the hub bolt 11. There is.

A shaft hole 210 that penetrates the body portion 21 in the axial direction is formed in the central portion of the hub 20. A spline fitting portion 210a is formed on the inner surface of the shaft hole 210, and the stem portion 721 of the joint member 72 of the drive shaft is fitted into the spline fitting portion 210a so as not to rotate relative to each other. The joint member 72 has a cup portion 722 having a diameter larger than that of the stem portion 721, and the cup portion 722 is in contact with the end portion of the inner member 2 on the vehicle inner side. Further, the joint member 72 has a male threaded portion 723 at an end on the vehicle outer side of the stem portion 721, and a nut 73 is screwed into the male threaded portion 723.

The first rolling element 4 and the second rolling element 5 are conical rollers made of, for example, bearing steel and having a large diameter portion and a small diameter portion integrally. The inner ring 200 is formed with a large brim 201 facing the large diameter portion of the second rolling element 5 and a small brim 202 facing the small diameter portion of the second rolling element 5. When a load is applied to the inner member 2 from the wheel 9 attached to the wheel mounting flange 22, the load acts on the first rolling element 4 more than the second rolling element 5. Next, the configuration of the first rolling element 4 and its peripheral portion will be described with reference to FIGS. 2 and 3.

FIG. 2 is an enlarged view showing the first rolling element 4 and its peripheral portion in FIG. 1 in an enlarged manner. FIG. 3 is a perspective view showing the first rolling element 4. Hereinafter, the first rolling element 4 is referred to as a conical roller 4. Further, the first inner raceway surface 2a is simply referred to as an inner raceway surface 2a. In FIG. 2, the center line C of the conical roller 4 is shown by a alternate long and short dash line.

The conical roller 4 is a conical roller having a large diameter portion 41 at one end in the axial direction on the wheel mounting flange side and a small diameter portion 42 at the other end in the axial direction, and is between the large diameter portion 41 and the small diameter portion 42. The outer peripheral surface of is a rolling surface 4a. The hub 20 has an annular brim portion 23 on which a brim surface 23a facing the large diameter portion 41 is formed. The conical roller 4 has an annular concave portion 410 recessed toward the small diameter portion 42 side along the center line C on the outer edge of the large diameter portion 41, and a convex portion 411 is formed inside the concave portion 410.

The convex portion 411 protrudes from the bottom surface 410a of the concave portion 410 along the center line C. In the present embodiment, the bottom surface 410a of the recess 410 is an annular plane perpendicular to the direction parallel to the center line C. The tip surface 411a of the convex portion 411 facing the brim surface 23a has a circular shape centered on the center point P intersecting the center line C. The side surface 411b of the convex portion 411 is an inclined surface that forms an obtuse angle with the bottom surface 410a of the concave portion 410 and is inclined with respect to the direction parallel to the center line C. In the conical roller 4, the tip surface 411a of the convex portion 411 slides in contact with the brim surface 23a and rolls on the inner raceway surface 2a.

In the present embodiment, the tip surface 411a of the convex portion 411 of the conical roller 4 is formed in a convex curved surface shape, and more specifically, in a partially spherical shape. In addition, in FIGS. 2A and 2B, the curvature of the tip surface 411a is exaggerated for the sake of clarification of the explanation. The brim portion 23 is formed so that the brim surface 23a faces a range including the center point P of the tip surface 411a of the convex portion 411. Further, the brim surface 23a is formed in a concave curved surface shape in the peripheral portion of the portion where the center point P of the tip surface 411a abuts in the axial cross section of the hub 20 along the rotation axis O. The radius of curvature of this concave curved portion is formed to be larger than the radius of curvature of the tip surface 411a of the convex portion 411. In the conical roller 4, the tip surface 411a at the center of the convex portion 411 including the center point P comes into contact with the brim surface 23a.

Further, in the present embodiment, the corner portion R is prevented from concentrating a large stress on the corner portion R between the inner raceway surface 2a and the brim surface 23a due to a load generated when the wheel 9 rides on the edge stone, for example. However, the inner raceway surface 2a is formed so as not to protrude inward in the radial direction (rotation axis O side) from the extension line L extending toward the wheel mounting flange 22 side. More specifically, in the axial cross section of the hub 20 along the rotation axis O, the corner portion R is formed in an arc shape having an arc angle substantially perpendicular to the arc angle.

One end of the corner portion R in the axial cross section of the hub 20 is smoothly continuous with the inner raceway surface 2a without a step, and the other end is smoothly continuous with the brim surface 23a without a step. _{The width W 1} in the direction perpendicular to the extension line L of the recess 410 in the large diameter portion 41 of the conical roller 4 is formed to be larger than _{the width W 2} of the corner portion R in the direction perpendicular to the extension line L. There is. The center point projection height of P of the convex portion 411 from the bottom surface 410a of the recess 410 is larger than the width W ₃ of the corner portion R in the direction along the extension L. As a result, the large diameter portion 41 of the conical roller 4 is configured so as not to come into contact with the corner portion R, and the space formed between the concave portion 410 and the corner portion R functions as a grease pool.

FIG. 4 is an explanatory view showing the grindstone G for grinding the inner raceway surface 2a and the brim surface 23a together with the cross section of the peripheral portion of the brim portion 23 in the hub 20. In the hub 20, for example, after forging a material made of carbon steel, the inner raceway surface 2a and the brim surface 23a are ground by the grindstone G. Grinding wheel G has a first grinding surface G ₁ for grinding a flange surface 23a, and a second grinding surface G ₂ for grinding the inner raceway surface 2a. The first grinding surface G ₁ is formed in a convex curved shape corresponding to the flange surface 23a. The first grinding surface G ₁ is may be linear. In this case, the concave curved brim surface 23a is formed by the movement of the grindstone G during the grinding process.

Further, the grindstone G has an arcuate third grinding surface G ₃ for grinding the corner portion R between the first grinding surface G ₁ and the second grinding surface G ₂ . Since the corner portion R does not come into contact with the large diameter portion 41 of the conical roller 4, the corner portion R does not necessarily have to be ground. The inner raceway surface 2a and the brim surface 23a are subjected to super-finishing, which is performed with higher precision after grinding with the grindstone G.

In the wheel bearing device 1, after the inner raceway surface 2a and the brim surface 23a are ground and superfinished, a plurality of conical rollers 4 held by the first cage 61 are assembled to the hub 20 to form a body portion 21. After arranging the outer member 3 on the outside, the inner ring 200 is arranged inside the outer member 3 together with the plurality of second rolling elements 5 and the second cage 62, and then the end portion of the body portion 21 is further added. It is assembled by tightening and fixing the inner ring 200 to the hub 20.

(Effect of the first embodiment)
According to the first embodiment described above, since the corner portion R is formed so as not to protrude inward in the radial direction from the extension line L of the inner raceway surface 2a, stress concentration in the vicinity of the corner portion R Is relaxed, and the strength of the inner member 2 is increased. Further, since the annular recess 410 is formed in the conical roller 4, the large diameter portion 41 of the conical roller 4 does not come into contact with the corner portion R, and even if the processing accuracy of the corner portion R is low, the conical roller 4 rolls. Does not adversely affect movement.

Further, according to the first embodiment, the strength of the inner member 2 is increased without performing a process of applying compressive residual stress to the corner portion R, so that an increase in cost can be suppressed and the conventional method can be performed. Since it is not necessary to form a sewn portion on the inner member as in the case of the wheel bearing device, the cost can be reduced.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 is a cross-sectional view showing a part of the wheel bearing device according to the second embodiment. FIG. 6 is a perspective view showing a conical roller according to the second embodiment.

In the first embodiment, the case where the tip surface 411a of the convex portion 411 of the conical roller 4 is formed in a convex curved surface shape has been described, but in the present embodiment, the central portion of the convex portion 411 of the conical roller 4 is formed. , A circular recessed portion 412 recessed toward the small diameter portion 42 side is provided. Further, in the present embodiment, the height of the brim portion 23 of the inner member 2 is lower than that of the first embodiment, and the brim portion 23 is on the inner diameter side (inner raceway surface 2a side) of the center position of the convex portion 411. ), The brim surface 23a is formed so that the convex portion 411 is in sliding contact with the convex portion 411. Since the other configurations are the same as those of the first embodiment, the components common to those described in the first embodiment in FIGS. 5 and 6 are those attached to FIGS. 1 to 3. The same reference numerals will be given and duplicate description will be omitted.

In the present embodiment, the tip surface 411a of the convex portion 411 of the conical roller 4 is an annular shape formed so as to surround the recessed portion 412. The brim surface 23a is formed in a convex curved surface shape that protrudes toward the tip surface 411a of the convex portion 411 in the radial direction inward from the center line C of the conical roller 4 in the axial cross section of the hub 20 along the rotation axis O. Has been done. _{The radial width W 1} of the recess 410 in the large diameter portion 41 of the conical roller 4 is formed to be larger than _{the width W 2} of the corner portion R in the direction perpendicular to the extension line L. The center point projection height of P of the convex portion 411 from the bottom surface 410a of the recess 410 is larger than the width W ₃ of the corner portion R in the direction along the extension L.

Also in the present embodiment, as in the first embodiment, the stress concentration near the corner portion R is relaxed, the strength of the inner member 2 is increased, and the cost can be reduced. Further, the recessed portion 412 functions as a grease reservoir, and the grease supplied from the recessed portion 412 between the tip surface 411a and the brim surface 23a of the convex portion 411 can smoothly roll the conical roller 4.

(Additional note)
Although the present invention has been described above based on the first and second embodiments, these embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be carried out by appropriately modifying it by omitting a part of the configuration or adding or replacing the configuration within a range not deviating from the gist thereof. For example, in the above embodiment, the case where the present invention is applied to a wheel bearing device that supports a drive wheel in which the driving force of the vehicle is transmitted via the drive shaft has been described, but the present invention is not limited to this. It is also possible to apply the present invention to a wheel bearing device that supports a driven wheel to which the transmission is not transmitted.

1 ... Wheel bearing device 2 ... Inner member 22 ... Wheel mounting flange 23 ... Brim portion 23a ... Brim surface 2a ... First inner raceway surface 2b ... Second inner raceway surface 3 ... Outer member 3a ... First Outer raceway surface 3b ... Second outer raceway surface 4 ... First rolling element (conical roller bearing) 41 ... Large diameter portion 410 ... Recessed 411 ... Convex portion 412 ... Recessed portion 42 ... Small diameter portion 5 ... Second rolling element 9 ... Wheel L ... Extension line O ... Rotation axis P ... Center position R ... Corner

Claims (3)

The first and second inner raceway surfaces are arranged in a double row on the outer periphery, and the inner member having a wheel mounting flange to which the wheels are mounted, and the first and second inner raceway surfaces. An outer member having first and second outer raceway planes facing each other formed on the inner circumference, and a plurality of first rolling elements that roll on the first inner raceway plane and the first outer raceway plane. A wheel having a second inner raceway surface and a plurality of second rolling elements that roll on the second outer raceway surface, and the inner member rotates about the rotation axis with respect to the outer member. It is a bearing device for
The first inner raceway surface is formed on the wheel mounting flange side with respect to the second inner raceway surface.
The first rolling element is a conical roller having a large diameter portion at one end in the axial direction on the wheel mounting flange side and a small diameter portion at the other end in the axial direction.
The inner member has an annular brim portion on which a brim surface facing the large diameter portion of the conical roller is formed, and has the first inner raceway surface and the inner raceway surface in an axial cross section along the rotation axis. The corner portion between the brim surface is formed so as not to protrude inward in the radial direction from the extension line extending the first inner raceway surface toward the wheel mounting flange side.
The conical roller has an annular recess recessed toward the small diameter portion on the outer edge of the large diameter portion, and the convex portion formed inside the recess is in sliding contact with the brim surface.
Bearing device for wheels. In the conical roller, the convex portion is formed in a convex curved surface shape.
The brim portion of the inner member is formed so that the brim surface faces a range including the center position of the convex portion.
The wheel bearing device according to claim 1. The conical roller is provided with a recessed portion recessed toward the small diameter portion at the center of the convex portion.
The brim portion of the inner member has a brim surface formed so that the convex portion slides on the inner diameter side of the center position of the convex portion.
The wheel bearing device according to claim 1.

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