WO2023013508A1

WO2023013508A1 - Vehicle wheel bearing device

Info

Publication number: WO2023013508A1
Application number: PCT/JP2022/029031
Authority: WO
Inventors: 大介仲; 将治勝部
Original assignee: Ntn株式会社
Priority date: 2021-08-06
Filing date: 2022-07-27
Publication date: 2023-02-09

Abstract

Provided is a vehicle wheel bearing device with which the ease of filling an injection molding of a holder with a resin is improved, and with which any increase in bearing torque can be minimized.　A vehicle wheel bearing device 1 comprising a plastic holder 7 which has a ring portion 7a formed in an annular shape and a plurality of column parts 7b axially extending from the ring portion 7a at regular intervals in the circumferential direction, and in which pockets Pt having curved surfaces 7e following the outer peripheral surfaces of rolling elements (balls 8) are formed by adjacent column parts 7b and the annular portion 7a, the rolling elements (8) being held in the pockets, and the column parts 7b being formed branching into inner-diameter sides and outer-diameter sides due to cut-away parts 7k, wherein, starting from an end part 7p of the ring portion 7a on the side axially opposite of the column parts 7b, the axial length a of each column part 7c on the inner-diameter side is less than the axial length b up to a center position P1 of the rolling element (8), and is greater than the axial length c up to an end part position P2 on the ring-portion 7a side of the cut-away part 7k.

Description

Wheel bearing device

The present invention relates to a wheel bearing device.

Conventionally, a wheel bearing device that rotatably supports a wheel in a suspension system of an automobile or the like is known. In a wheel bearing device, an inner member including a hub wheel is rotatably supported by an outer member via a plurality of rolling elements (here, balls). The plurality of balls are evenly distributed in the circumferential direction by the retainer and held in a state in which contact between adjacent balls is prevented.

In such a wheel bearing device, it is possible to increase the number of balls by reducing the thickness in the circumferential direction of the column portion of the retainer that separates the adjacent balls and by forming a notch portion in the column portion. , which makes it possible to increase the service life of the bearing while making the retainer free from the problem of insufficient strength. For example, it is as described in Patent Document 1 and Patent Document 2.

In the cages disclosed in

Patent Documents

1 and 2, the thickness of the columns in the cage is reduced in the circumferential direction, and notches are formed in the portions where the adjacent balls are closest to each other. ing. In other words, adjacent balls do not have a pillar portion intervening in their closest portions. As a result, the retainer has a structure in which the number of balls that can be incorporated is increased by shortening the distance between the balls in the circumferential direction.

EP-A-0592839 Japanese Patent Application Laid-Open No. 2005-180630

In the retainers described in

Patent Documents

1 and 2, the column portion is bifurcated into two on the inner diameter side and the outer diameter side by the notch. In Patent Document 1, as shown in FIG. 7A, starting from the end of the annular portion on the opposite side of the axial direction from the column, the axial length a1 of the column on the inner diameter side is the axial length a1 to the center position of the ball. It is almost the same as the directional length b1. In Patent Literature 2, as shown in FIG. 7B, starting from the end of the annular portion on the opposite side of the axial direction from the pillar, the axial length a2 of the pillar on the inner diameter side is the axis to the center position of the ball. longer than the directional length b2. Such a shape of the pillars on the inner diameter side raises concerns that the resin may not reach the tips of the pillars during injection molding of the cage, resulting in insufficient resin filling, and the quality of the cage may be unstable.

In addition, with the recent trend toward lower fuel consumption of vehicles, lower torque is required for wheel bearing devices. In the retainer, shear resistance of the grease occurs between the retainer and the balls when the wheel bearing device rotates, leading to an increase in bearing torque. Therefore, improvement is desired.

Therefore, an object of the present invention is to provide a bearing device for a wheel that can improve the filling property of the resin in the injection molding of the retainer and can suppress the increase of the bearing torque.

That is, the first invention comprises an outer member having a double-row outer raceway surface formed on the inner circumference thereof, and an inner member having a double-row inner raceway surface facing the double-row outer raceway surface. , a double-row rolling element rotatably interposed between the raceway surfaces of the outer member and the inner member; an annular portion formed in an annular shape; a plurality of pillars extending in the axial direction at intervals of , and the adjacent pillars and the annular portion form a pocket having a curved surface along the outer peripheral surface of the rolling element, and the pocket includes the rolling element and a resin retainer that holds the pillar, wherein the pillar is branched into an inner diameter side and an outer diameter side by a notch, wherein the pillar is axially opposite to the pillar Starting from the end of the annular portion on the inner diameter side, the axial length of the column portion on the inner diameter side is shorter than the axial length to the center position of the rolling element, and the annular portion of the cutout portion It is longer than the axial length to the end position of the side.

The effects of the present invention are as follows.

That is, according to the first invention, the ability to fill the column with the resin is improved, and the shear resistance of the grease between the ball and the column is reduced. Therefore, it is possible to improve the filling property of the resin in the injection molding of the retainer and to suppress the increase in the bearing torque.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the whole structure of a wheel bearing apparatus. FIG. 4 is an enlarged cross-sectional view showing the configuration of balls and a retainer; The top view which shows the whole structure of a retainer. Sectional drawing which shows the whole structure of a retainer. FIG. 4 is an enlarged cross-sectional view showing the axial length of a column portion on the inner diameter side; The enlarged perspective view which shows the position of a gate part and a weld. FIG. 7A is an enlarged cross-sectional view showing the axial length of an inner diameter-side column in a conventional cage, and FIG. 7B is an enlarged cross-sectional view showing the axial length of an inner diameter-side column in a conventional cage. figure. BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the whole structure of a wheel bearing apparatus. FIG. 4 is an enlarged cross-sectional view showing the configuration of balls and a retainer; The top view which shows the whole structure of a retainer. Sectional drawing which shows the whole structure of a retainer. FIG. 4 is an enlarged cross-sectional view showing the axial length of the inner diameter side end of the retainer; The enlarged perspective view which shows the structure of a column part.

A wheel bearing device 1, which is one embodiment of the wheel bearing device according to the present invention, will be described below with reference to FIGS. 1 and 2. FIG.

As shown in FIG. 1, a wheel bearing device 1 rotatably supports a wheel in a suspension system of a vehicle such as an automobile. A wheel bearing device 1 includes an outer ring 2 as an outer member, a hub ring 3 as an inner member, an inner ring 4, two inner ball rows 5 as rolling rows, an outer ball row 6, and a sealing member. An inner side seal member 9 and an outer side seal member 10 are provided. Here, in this specification, the inner side refers to the vehicle body side of the wheel bearing device 1 when the wheel bearing device 1 is attached to the vehicle body, and the outer side refers to the wheel bearing device 1 attached to the vehicle body. 1 shows the wheel side of the wheel bearing device 1 when it is closed. Further, the direction parallel to the rotation axis of the wheel bearing device 1 is the "axial direction", the direction orthogonal to the rotation axis of the wheel bearing device 1 is the "radial direction", and the rotation axis of the wheel bearing device 1 is the center. A direction along the arc is referred to as a “circumferential direction”. In addition, the side away from the inside of the bearing along the rotation axis is referred to as "axial outside", and the side closer to the inside of the bearing along the rotation axis is referred to as "axial inside".

The outer ring 2 supports the hub wheel 3 and the inner ring 4 via the inner ball row 5 and the outer ball row 6 . The outer ring 2 is formed in a substantially cylindrical shape. An inner-side opening 2a into which an inner-side seal member 9 can be fitted is formed at the inner-side end of the outer ring 2 . An outer-side opening 2b into which an outer-side sealing member 10 can be fitted is formed at the outer-side end of the outer ring 2 .

The inner diameter surface of the outer ring 2 is provided with an inner side raceway surface 2c and an outer side raceway surface 2d. An outer peripheral surface of the outer ring 2 is integrally formed with a vehicle body attachment flange 2e for attachment to a knuckle of a suspension system.

The hub wheel 3 rotatably supports the wheels of the vehicle. The hub wheel 3 is formed in a cylindrical shape. A small-diameter stepped portion 3a having a reduced diameter is formed on the outer peripheral surface of the inner side end portion of the hub wheel 3 . A wheel mounting flange 3b for mounting a wheel is integrally formed on the outer side end of the hub wheel 3. As shown in FIG. Hub bolts 3d are inserted through the wheel mounting flange 3b at equidistant positions on the circumference. Further, the hub wheel 3 is arranged such that the outer side inner raceway surface 3c faces the outer side raceway surface 2d of the outer ring 2 . The hub wheel 3 has an inner ring 4 fitted to a small-diameter stepped portion 3a.

The inner ring 4 applies preload to the inner ball row 5 and the outer ball row 6 . An annular inner raceway surface 4 a is formed in the circumferential direction on the outer peripheral surface of the inner ring 4 . The inner ring 4 is fixed to the inner end of the hub wheel 3 by caulking. In other words, the inner raceway surface 4 a is formed by the inner ring 4 on the inner side of the hub wheel 3 . The inner race 4 is arranged such that its inner raceway surface 4a faces the inner side outer raceway surface 2c of the outer race 2 .

In the inner ball row 5 and the outer ball row 6, a plurality of balls 8, which are rolling elements, are annularly held by a retainer 7 made of resin. The inner ball row 5 is rotatably interposed between the inner raceway surface 4a of the inner ring 4 and the outer raceway surface 2c of the outer ring 2 on the inner side. The outer-side ball train 6 is rotatably interposed between the inner raceway surface 3c of the hub wheel 3 and the outer-side raceway surface 2d of the outer ring 2 .

The cage 7 holds the balls 8. The retainer 7 is made of synthetic resin such as polyamide 46 (PA46), polyamide 66 (PA66), polyamide 9T (PA9T), polyetheretherketone (PEEK), polyphenylene sulfide ( PPS), etc. Further, as a reinforcing material, glass fiber, carbon fiber, or the like may be contained in the resin.

As shown in FIG. 2, the retainer 7 has an annular ring portion 7a and a plurality of column portions 7b. The column portion 7b extends axially outward from the annular portion 7a. The pillars 7b are arranged at regular intervals along the circumferential direction of the annular portion 7a. Pockets Pt for independently holding balls 8 are formed in cage 7 between adjacent pillars 7b at regular intervals (see FIG. 3).

The ball 8 is composed of a steel ball or the like made of high-carbon chromium bearing steel SUJ2. A plurality of balls 8 are rotatably held in pockets Pt of retainer 7 .

As shown in FIG. 1 , the inner side seal member 9 closes the gap between the inner side opening 2 a of the outer ring 2 and the inner ring 4 . The inner side seal member 9 is composed of, for example, a two-side lip type pack seal that brings two seal lips into contact with each other. The inner side seal member 9 includes a substantially cylindrical seal plate and a substantially cylindrical slinger.

The outer-side sealing member 10 closes the gap between the outer-side opening 2b of the outer ring 2 and the hub wheel 3. The outer-side seal member 10 has a plurality of seal lips made of a synthetic rubber such as NBR (acrylonitrile-butadiene rubber) fixed to a substantially cylindrical core made of a steel plate made of the same material as the seal plate.

Next, the retainer 7 according to the first embodiment will be described in detail with reference to FIGS. 2 to 4. FIG.

As shown in FIG. 2, the annular portion 7a is located axially inward of the center position P1 of the ball 8. As shown in FIG. The column portions 7b are provided on the inner diameter side and the outer diameter side of the ring portion 7a, respectively. The column portion 7c on the inner diameter side extends axially from the annular portion 7a. The column portion 7d on the outer diameter side includes a first portion 7f that extends from the annular portion 7a so as to be inclined away from the outer peripheral surface of the annular portion 7a toward the outer diameter side, and a first portion 7f that extends along the axial direction from the first portion 7f. and a second portion 7g extending along the length thereof.

The axial end face S1 of the inner diameter side column portion 7c is formed closer to the annular portion 7a than the axial end face S2 of the outer diameter side column portion 7d. That is, the pillar portion 7c on the inner diameter side is formed to be shorter in the axial direction than the pillar portion 7d on the outer diameter side.

As shown in FIGS. 3 and 4, a curved surface along the outer peripheral surface of the ball 8 is formed in a portion composed of the annular portion 7a side of the opposing side surface of the adjacent column portion 7b and the annular portion 7a therebetween. 7e is formed in a substantially hemispherical shape with the annular portion 7a as the bottom. Further, a guide surface 7h extending straight in the axial direction from the edge of the semispherical curved surface 7e toward the tip of the column portion 7b is formed on the column portion 7d on the outer diameter side (see FIG. 6). The guide surface 7h is configured to guide the ball 8 from the tip of the column portion 7b to the space surrounded by the curved surface 7e. As a result, pockets Pt for holding the balls 8 are formed at regular intervals in the retainer 7 from the curved surfaces 7e and the guide surfaces 7h between the adjacent pillars 7b.

The minimum distance between adjacent balls 8 on the pitch circle PCD is regulated by the balls 8 coming into contact with the inner surface of the column portion 7b. The thickness of the pillar portion 7b is the thinnest on the pitch circle PCD, and gradually increases toward the inner diameter side and the outer diameter side thereof.

The curved surface 7e of the column portion 7b is curved with the substantially central portion of the adjacent column portion 7b as the bottom. The interval between the adjacent column portions 7b is formed such that the interval Wi between the inner diameter side end portions and the interval Wo between the radial outer end portions are smaller than the interval Wc between the radial centers. Thereby, the column portion 7b restricts the movement of the ball 8 arranged inside the pocket Pt to the radially inner side and the radially outer side. Claw portions 7j projecting toward the adjacent column portions 7b on both sides in the circumferential direction are formed at the tip portions of the column portions 7d on the outer diameter side (see FIG. 6).

As shown in FIG. 2, a notch portion 7k having a curved surface with a predetermined radius is formed at substantially the central portion of the radial width of the column portion 7b. The notch portion 7k branches off the inner diameter side column portion 7c and the outer diameter side column portion 7d, and is formed by removing a member in the substantially central portion of the radial width of the column portion 5b. For example, the notch portion 7k is formed so as to remove a portion that does not have the required strength around the portion where the thickness of the column portion 7b is the thinnest due to the curved surface 7e and the guide surface 7h (see FIG. 6). It is The shape of the notch portion 7k is not particularly limited. At the tip of the inner diameter side column portion 7c, the facing surfaces of the inner diameter side column portion 7c and the outer diameter side column portion 7d extend in parallel. It may be formed by removing the member of the column portion 5b as shown in FIG. An end position P2 of the notch portion 7k on the side of the ring portion 5a is positioned closer to the ring portion 7a than the center position P1 of the ball 8 is. Further, the center position P1 of the ball 8 is positioned within the range of the radial width W (see FIG. 5) of the notch portion 7k. That is, the column portion 7b is formed so as not to overlap the center position P1 of the ball 8 in the circumferential direction. With this configuration, the retainer 7 can reduce the intervals between the balls 8 and increase the number of balls 8 to be retained.

Next, using FIGS. 5 and 6, the features and effects of the wheel bearing device 1 according to the first embodiment will be described. Hereinafter, the axial length will be described with the end portion 7p of the annular portion 7a on the opposite side of the column portion 7c in the axial direction as the starting point.

As shown in FIG. 5, the retainer 7 is bifurcated into a column portion 7c on the inner diameter side and a column portion 7d on the outer diameter side by a notch portion 7k. The column portion 7c on the inner diameter side is formed such that its axial length a is shorter than the axial length b up to the center position P1 of the ball 8. As shown in FIG. Further, the inner diameter side column portion 7c is formed such that its axial length a is longer than the axial length c up to the end position P2 of the notch portion 7k on the annular portion 5a side. That is, the axial length a of the pillar 7c on the inner diameter side is shorter than the axial length b up to the center position P1 of the ball 8, and the length up to the end position P2 of the notch 7k on the side of the annular portion 5a. longer than the axial length c.

In addition, the axial length of the column portion 7d on the outer diameter side is formed to be longer than the axial length b to the center position P1 of the ball 8. As shown in FIG. As a result, the pillar portion 7d on the outer diameter side restricts the movement of the ball 8 in the axial direction by means of the pawl portion 7j (see FIG. 6).

As described above, in the wheel bearing device 1, the axial length a of the inner diameter side column portion 7c is formed to be shorter than in the conventional case, so that the column portion 7b can be filled with resin more easily. In addition, the shear resistance of the grease between the column portion 7b and the balls 8 is reduced by reducing the approaching area of the balls 8 and the retainer 7. As shown in FIG. Therefore, it is possible to improve the filling property of the resin in the injection molding of the retainer 7 and suppress the increase of the bearing torque. In addition, since the fillability of the resin into the column portion 7b is improved, the moldability of the retainer 7 is improved, and the strength of the retainer 7 can be ensured. In addition, since the axial length a of the pillar portion 7c on the inner diameter side is formed shorter than the conventional one, the weight of the retainer 7 can be reduced.

The retainer 7 is a resin injection molded body. The retainer 7 is injected with resin from the gate of the mold into the mold during injection molding. The retainer 7 has a gate portion 7m, and the gate portion 7m is positioned at a location corresponding to the gate of the mold. The retainer 7 has a weld 7n formed by merging the resin filled from the gate portion 7m.

As shown in FIG. 6, the gate portion 7m is provided on the inner diameter surface of the annular portion 7a and is positioned on the extension of the inner diameter side column portion 7c in the axial direction. That is, the gate portion 7m is provided on the annular portion 7a and positioned on the extension of the column portion 7b in the axial direction. Also, the weld 7n is positioned between the column portions 7b. The gate portions 7m are provided at several locations, and the number of the gate portions to be provided is determined according to the retainer 7. As shown in FIG. Note that the weld 7n has a lower strength than other portions where the weld 7n is not formed. Since the number of welds 7n formed increases according to the number of gate portions 7m, it is preferable to minimize the number of gate portions 7m to the extent that the resin can be filled.

As described above, in the wheel bearing device 1, the gate portion 7m filled with resin is provided in the annular portion 7a and positioned on the extension of the column portion 7b in the axial direction. Fillability can be improved. In addition, the formability of the retainer 7 can be improved by avoiding the formation of the weld 7n in the column portion 7b.

Next, other features and effects of the wheel bearing device 1 will be described with reference to FIG.

In the wheel bearing device 1, grease is sealed inside the bearing in which the balls 8 are provided. The kinematic viscosity of the grease is preferably 30 mm ² /s to 200 mm ² /s. If the kinematic viscosity of the grease is too low, the formation of the oil film will be insufficient, possibly damaging the cage 7 and the like. On the other hand, if the kinematic viscosity of the grease is too high, the viscous resistance increases, resulting in an increase in temperature and friction loss. In the wheel bearing device 1, the kinematic viscosity of the grease is optimized by setting the kinematic viscosity to 30 mm ² /s to 200 mm ² /s as described above.

A pocket clearance e is provided between the pocket Pt and the ball 8 . The pocket clearance e is preferably 0.05 mm to 0.45 mm. The retainer 7 can move freely with respect to the balls 8 within the range of the pocket clearance e. If the pocket clearance e is too small, the pocket Pt and the ball 8 may interfere with each other and be damaged. On the other hand, if the pocket clearance e is too large, the ball 8 will rattle in the pocket Pt, degrading the acoustic characteristics. In the wheel bearing device 1, the pocket clearance e is optimized by setting the pocket clearance e to 0.05 mm to 0.45 mm as described above.

Next, the retainer 70 according to the second embodiment will be described in detail with reference to FIGS. 8 to 11. FIG. In the following, parts that are different from the wheel bearing device 1 and the retainer 7 according to the first embodiment will be described.

As shown in FIG. 9, the annular portion 7A is located axially inside the center position P1 of the ball 8. As shown in FIG. The column portion 7B does not branch to the inner diameter side of the circular ring portion 7A, but extends from the circular ring portion 7A so as to be away from the outer diameter surface 7Q of the circular ring portion 7A. It extends along the axial direction from the portion that extends along the axial direction.

As shown in FIGS. 10 and 11 , a curved surface along the outer peripheral surface of the ball 8 is formed in a portion composed of the annular portion 7A side of the opposing side surfaces of the adjacent columnar portions 7B and the annular portion 7A therebetween. 7C is formed in a substantially hemispherical shape with the annular portion 7A as the bottom. Further, the column portion 7B is formed with a guide surface 7D extending straight in the axial direction from the edge of the hemispherical curved surface 7C toward the tip of the column portion 7B (see FIG. 13). The guide surface 7D is configured to guide the ball 8 from the tip of the column portion 7B to the space surrounded by the curved surface 7C. Thus, pockets Pt for holding the balls 8 are formed at equal intervals in the retainer 70 from the curved surfaces 7C and the guide surfaces 7D between the adjacent pillars 7B.

The minimum distance between adjacent balls 8 on the pitch circle PCD is regulated by the balls 8 coming into contact with the inner surface of the column portion 7B. The thickness of the column portion 7B is the thinnest on the pitch circle PCD, and gradually increases toward the inner diameter side and the outer diameter side thereof.

The curved surface 7C of the column portion 7B is curved with the substantially central portion of the adjacent column portion 7B as the bottom. The interval between the adjacent pillars 7B is formed such that the interval Wi between the inner diameter side ends and the interval Wo between the radially outer ends are smaller than the interval Wc between the radial centers. Thereby, the column portion 7B restricts the movement of the ball 8 arranged inside the pocket Pt to the radially inner side and the radially outer side. Claw portions 7E projecting toward adjacent column portions 7B on both sides in the circumferential direction are formed at the tip portions of the column portions 7B (see FIG. 13).

As shown in FIG. 9, the column portion 7B has a root portion 7F extending axially outward from the annular portion 7A, and branch portions 7G extending axially outward from the outer diameter side of the root portion 7F. . Moreover, the branch portion 7G extends on the outer diameter side of the annular portion 7A. That is, there is no branch portion 7G on the inner diameter side of the ring portion 7A.

The root portion 7F holds the ball 8 on the base end side of the column portion 7B. The root portion 7F has an inner diameter surface 7H and an inclined surface 7J. The inner diameter surface 7H is formed to extend axially outward from the inner diameter surface 7K of the annular portion 7A. The inclined surface 7J is formed so as to extend from the inner diameter surface 7H so as to be inclined away from the inner diameter surface 7H, and is connected to the branch portion 7G (curved surface 7M).

The branch portion 7G holds the ball 8 on the tip side of the column portion 7B. The branch portion 7G is formed only on the outer diameter side of the root portion 7F. Specifically, the radial center line L of the branch portion 7G is located on the outer diameter side of the outer diameter surface 7Q of the annular portion 7A. The branch portion 7G has a curved surface 7M, an inner diameter surface 7N, and an axial end surface S. The curved surface 7M is formed extending from the inclined surface 7J in an arcuate cross-section. The inner diameter surface 7N is formed so as to extend axially from the curved surface 7M toward the axial end surface S of the column portion 7B. In this manner, the column portion 7B has a configuration in which the branch portion extending in the axial direction is not formed on the inner diameter side of the root portion 7F. Note that the radial center line L is a line parallel to the axial direction and passes through the radial center of the axial end surface S.

The inner diameter surface 7N is located on the outer diameter side of the center position P1 of the ball 8. In addition, the inclined surface 7J is positioned closer to the annular portion 7A than the center position P1 of the ball 8. As shown in FIG. That is, the column portion 7B is formed so as not to overlap the center position P1 of the ball 8 in the circumferential direction. With this configuration, the retainer 70 can reduce the intervals between the balls 8 and increase the number of balls 8 to be retained. The shapes of the surfaces of the root portion 7F and the branch portions 7G can be appropriately changed in design. For example, although the inclined surface 7J is illustrated as extending straight, it may be bent or curved.

Next, the axial length to the tip position P3 on the inner diameter surface 7H of the root portion 7F will be described in detail with reference to FIGS. Hereinafter, the axial length will be described with the end portion 7P of the annular portion 7A on the opposite side in the axial direction from the root portion 7F as the starting point.

As shown in FIG. 12, the retainer 70 has an axial length f up to the tip position P3, which is an axial length g up to the base end position of the branch portion 7G (an axial length g up to the base end position P4 of the curved surface 7M). length). Further, the retainer 70 is formed such that the axial length f up to the tip position P3 is longer than the axial length h up to the tip position P5 on the inner diameter surface 7K of the annular portion 7A. That is, the axial length f to the tip position P3 is shorter than the axial length g to the base end position of the branch portion 7G, and the axial length to the tip position P5 on the inner diameter surface 7K of the annular portion 7A. longer than h.

The column portion 7B is formed so that the axial length to the axial end face S is longer than the axial length to the center position P1 of the ball 8 . Thus, the column portion 7B restricts axial movement of the ball 8 by means of the pawl portion 7E (see FIG. 13).

As described above, in the wheel bearing device 1A, since the branch portion extending in the axial direction is not formed on the inner diameter side of the root portion 7F, the filling property of the resin on the inner diameter side of the retainer 70 is improved. In addition, the shear resistance of the grease between the column portion 7B and the balls 8 is reduced by reducing the approaching area between the balls 8 and the retainer 70 . Therefore, it is possible to improve the filling property of the resin in the injection molding of the retainer 70 and suppress the increase of the bearing torque. In addition, since the filling property of the resin to the inner diameter side of the retainer 70 is improved, the moldability of the retainer 70 is improved and the strength of the retainer 70 can be ensured. Moreover, since the branch portion extending in the axial direction is not formed on the inner diameter side of the root portion 7F, the weight of the retainer 70 can be reduced.

Next, other features and effects of the wheel bearing device 1A according to the second embodiment will be described with reference to FIGS. 9 and 13. FIG.

In the wheel bearing device 1A, grease is sealed inside the bearing in which the balls 8 are provided. The kinematic viscosity of the grease is preferably 30 mm ² /s to 200 mm ² /s. If the kinematic viscosity of the grease is too low, the formation of the oil film will be insufficient, possibly damaging the retainer 70 and the like. On the other hand, if the kinematic viscosity of the grease is too high, the viscous resistance increases, resulting in an increase in temperature and friction loss. In the wheel bearing device 1A, the kinematic viscosity of the grease is optimized by setting the kinematic viscosity to 30 mm ² /s to 200 mm ² /s as described above.

Also, a pocket clearance j is provided between the pocket Pt and the ball 8 . The pocket clearance j is preferably 0.05 mm to 0.45 mm. The cage 70 can move freely with respect to the balls 8 within the range of the pocket clearance j. If the pocket clearance j is too small, the pocket Pt and the ball 8 may interfere with each other and be damaged. On the other hand, if the pocket clearance j is too large, the ball 8 will rattle in the pocket Pt, degrading the acoustic characteristics. In the wheel bearing device 1A, the pocket clearance j is optimized by setting the pocket clearance j to 0.05 mm to 0.45 mm as described above.

Also, the retainer 70 is a resin injection molded body. The retainer 70 is injected with resin from the gate of the mold into the mold during injection molding. The retainer 70 has a gate portion 7R, and the gate portion 7R is positioned at a location corresponding to the gate of the mold. The retainer 70 has a weld 7S formed by merging the resin filled from the gate portion 7R.

As shown in FIG. 13, the gate portion 7R is provided on the inner diameter surface 7K of the annular portion 7A and positioned on the extension of the column portion 7B in the axial direction. Also, the weld 7S is positioned between the pillars 7B. The gate portions 7R are provided at several locations, and the number of the gate portions to be provided is determined according to the retainer 70. As shown in FIG. Note that the weld 7S has a lower strength than other portions where the weld 7S is not formed. Since the number of welds 7S to be formed increases according to the number of gate portions 7R installed, it is preferable to minimize the number of gate portions 7R to be installed within a range in which the resin can be filled.

As described above, in the wheel bearing device 1A, the gate portion 7R filled with resin is provided in the annular portion 7A and positioned on the extension of the column portion 7B in the axial direction. Fillability can be improved. Also, by preventing the formation of the weld 7S in the column portion 7B, the moldability of the retainer 70 can be improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments at all, but is merely an example, and further various forms are possible without departing from the scope of the present invention. The scope of the present invention is indicated by the description of the claims, and includes all changes within the meaning and range of equivalents described in the claims. In the present embodiment, the

wheel bearing device

1, 1A is configured as a wheel bearing device having a third-generation structure in which the inner raceway surface 3c is directly formed on the outer periphery of the hub wheel 3, but is limited to this. However, even if it is a second generation structure in which a pair of inner rings are press-fitted and fixed to the hub ring, or a first generation structure in which a double row angular contact ball bearing is fitted between the knuckle and the hub ring, good.

The present invention can be used for wheel bearing devices.

1 wheel bearing device 1A wheel bearing device 2 outer ring (outer member)
2c outer raceway surface 2d outer raceway surface 3 hub ring (inner member)
3c inner raceway surface 4 inner ring (inner member)
4a inner raceway surface 5 inner ball row 6 outer ball row 7 retainer 7a annular portion 7b column portion 7c inner diameter column portion 7d outer diameter column portion 7e curved surface along the outer peripheral surface of the rolling element 7m gate portion 7n Weld 7p Annular end on opposite side of column 70 Retainer 7A Annular 7B Column 7F Root 7G Branch 7H Inner diameter surface of root 7J Inclined surface of root 7K Inner diameter of annular Surface 7N Inner diameter surface of the branch portion 7P End portion of the annular portion on the opposite side of the root portion in the axial direction 7Q Outer diameter surface of the annular portion 7R Gate portion 7S Weld 8 Ball (rolling element)
a Axial length of the column on the inner diameter side b Axial length to the center of the rolling element c Axial length to the end of the notch on the annular side e Pocket clearance f Inner diameter of the root Axial length to the tip position on the surface g Axial length to the base end position of the branch h Axial length to the tip position on the inner diameter surface of the annular part j Pocket clearance L Radial centerline P1 Ball Center position P2 Edge position of the notch on the annular side P3 Tip position of the inner diameter surface of the root P5 Tip position of the inner diameter surface of the annular portion Pt Pocket W Radial width of the notch

Claims

an outer member having a double-row outer raceway surface formed on the inner circumference;
an inner member formed with double-row inner raceway surfaces facing the double-row outer raceway surfaces;
a double-row rolling element rollably interposed between the raceway surfaces of the outer member and the inner member;
An annular portion formed in an annular shape and a plurality of pillars extending axially from the annular portion at regular intervals in the circumferential direction, and the adjacent pillars and the annular portion form the rolling element. A pocket having a curved surface along the outer peripheral surface is formed, the pocket is provided with a resin retainer that retains the rolling element, and the column portion is branched into an inner diameter side and an outer diameter side by a notch portion. A wheel bearing device formed comprising:
Starting from the end of the annular portion axially opposite to the column portion, the axial length of the column portion on the inner diameter side is shorter than the axial length to the center position of the rolling element. A wheel bearing device, wherein the axial length of the notched portion to the end position on the annular portion side is longer than that of the notched portion.
2. The wheel bearing device according to claim 1, wherein an end position of the cutout portion on the annular portion side is located closer to the annular portion side than a center position of the rolling element. .
The wheel bearing device according to claim 1 or 2, characterized in that the center position of the rolling element is positioned within the range of the radial width of the notch portion.
The retainer is an injection molded body having a gate portion, and the gate portion is positioned corresponding to a gate of a mold into which resin is injected during injection molding,
The wheel bearing device according to any one of claims 1 to 3, wherein the gate portion is provided on the annular portion and positioned on an extension of the column portion in the axial direction. .
The retainer has a weld formed by joining the resin filled from the gate portion,
5. The wheel bearing device according to claim 4, wherein the weld is positioned between the columns.
Grease is sealed inside the bearing in which the rolling elements are arranged,
The wheel bearing device according to any one of claims 1 to 5, wherein the grease has a kinematic viscosity of 30 mm 2 /s to 200 mm 2 /s.
The wheel bearing device according to any one of claims 1 to 6, characterized in that the pocket clearance between the rolling element and the pocket is 0.05 mm to 0.45 mm.
an outer member having a double-row outer raceway surface formed on the inner circumference;
an inner member formed with double-row inner raceway surfaces facing the double-row outer raceway surfaces;
a double-row rolling element rollably interposed between the raceway surfaces of the outer member and the inner member;
An annular portion formed in an annular shape and a plurality of pillars extending axially from the annular portion at regular intervals in the circumferential direction, and the adjacent pillars and the annular portion form the rolling element. A wheel bearing device comprising: a pocket having a curved surface along an outer peripheral surface; and a resin retainer for holding the rolling element in the pocket,
The column portion has a root portion extending axially from the annular portion and branch portions extending axially from the root portion, and the branch portions are formed only on the outer diameter side of the root portion. A wheel bearing device characterized by:
The wheel bearing device according to claim 8, wherein the radial center line of the branch portion is located on the outer diameter side of the outer diameter surface of the annular portion.
the root portion has an inner diameter surface of the root portion extending in the axial direction from the inner diameter surface of the annular portion;
Starting from the end of the annular portion axially opposite to the root portion, the axial length to the tip position on the inner diameter surface of the root portion is greater than the axial length to the base end position of the branch portion. 10. The wheel bearing device according to claim 8, wherein the length in the axial direction to the tip position on the inner diameter surface of the annular portion is shorter than the length in the axial direction.
The wheel bearing device according to any one of claims 8 to 10, wherein the inner diameter surface of the branch portion is located on the outer diameter side of the center position of the rolling element.
The root portion has an inclined surface connected to the branch portion on the inner diameter side of the root portion,
The wheel bearing device according to any one of claims 8 to 11, wherein the inclined surface of the root portion is located closer to the annular portion than the center position of the rolling element.
Grease is sealed inside the bearing in which the rolling elements are arranged,
The wheel bearing device according to any one of claims 8 to 12, wherein the grease has a kinematic viscosity of 30 mm 2 /s to 200 mm 2 /s.
The wheel bearing device according to any one of claims 8 to 13, characterized in that the pocket clearance between the rolling element and the pocket is 0.05 mm to 0.45 mm.
The retainer is an injection molded body having a gate portion, and the gate portion is positioned corresponding to a gate of a mold into which resin is injected during injection molding,
15. The wheel bearing device according to any one of claims 8 to 14, wherein the gate portion is provided on the annular portion and positioned on an extension of the column portion in the axial direction. .
The retainer has a weld formed by joining the resin filled from the gate portion,
16. The wheel bearing device according to claim 15, wherein the weld is positioned between the columns.