Cage for bearing device and wheel bearing device including same

Abstract

To provide a cage for a bearing device which can prevent a deformation and the damage of a column part during mold release, and makes grease easily flow in around rolling bodies at the rotation of a bearing, and a wheel boarding device having the same.SOLUTION: In a cage for a bearing device (cage 7) having a circular ring part 2a which is formed into an annular shape, a plurality of column parts 2b extending to the outside in an axial direction from the circular ring part 2a at constant intervals, and pockets Pt having pocket curved faces (an axial-direction inside curved face 7g and an axial-direction outside curved face 7k) being curved faces which are formed so as to progress along external peripheral faces of balls 8 by the adjacent column parts 2b and the circular ring parts 2a, and holding the balls 8, the column parts 2b are formed into linear shapes extending in an axial direction at the inside of the axial direction at an outside-diameter side with respect to curvature radius center positions P of the pocket curved faces (7g, 7k), and formed into linear shapes extending in the axial direction at the inside of the axial direction at an inside-diameter side with respect to the curvature radius center positions P of the pocket curved faces (7g, 7k).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a cage for a bearing device and a wheel bearing device including the cage. [Background technology]

[0002] Conventionally, wheel bearing devices that rotatably support wheels in suspension systems for automobiles and the like have been known. In wheel bearing devices, an inner member including a hub ring is rotatably supported on an outer member via a plurality of rolling elements (here, balls). The plurality of balls are evenly distributed in the circumferential direction by a cage and are held in a state in which adjacent balls are prevented from contacting each other.

[0003] Incidentally, Patent Document 1 describes a cage for a rolling bearing. The cage has a nylon resin cage base body, and the entire surface of the cage is coated with a polymer resin coating that is more heat resistant than the nylon resin and impermeable to oxygen, to prevent oxidation degradation of the cage base body. The cage has a structure in which the entire pocket surface is spherical, and press-fitted steel balls are held in the pockets. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3108477 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the cage described in Patent Document 1 above has the risk of deformation or damage because the axially outer side of the pocket surface (the tip side of the column portion) is pushed out when the injection mold that forms the pocket surface is removed from the cage (during demolding).In addition, because the axially outer side of the pocket surface is formed to fit along the outer circumferential surface of the ball, there is a problem in that it is difficult for grease present on the axially outer side (the sealing member side) to flow around the rolling elements when the bearing rotates.

[0006] Therefore, the present invention provides a retainer for a bearing device that can prevent deformation or damage to the column portion when released from the mold and that allows grease to easily flow around the rolling elements when the bearing rotates, and a wheel bearing device that includes the retainer. [Means for solving the problem]

[0007] That is, the first invention is a circular ring portion formed in an annular shape, a plurality of pillar portions extending axially outward from the annular portion at regular intervals in the circumferential direction; a pocket having a curved pocket surface that is a curved surface formed by adjacent column portions and annular portions so as to fit along an outer peripheral surface of the ball, the pocket holding the ball, The column portion is On the outer diameter side with respect to the center of curvature of the pocket curved surface, the axially inner side has a linear shape extending in the axial direction, On the inner diameter side of the center of curvature of the pocket curved surface, the axially outer side has a linear shape extending in the axial direction. [Effects of the Invention]

[0008] The present invention has the following effects.

[0009] That is, according to the first invention, deformation and damage to the column portion during demolding can be prevented, and grease can easily flow around the rolling elements when the bearing rotates. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing the overall configuration of a wheel bearing device; [Figure 2] FIG. 4 is an enlarged cross-sectional view showing the configuration of the ball and the cage. [Figure 3] FIG. [Figure 4] FIG. 4 is an enlarged perspective view showing a linear shape formed on the cage. [Figure 5] FIG. [Figure 6] 6 is a cross-sectional view of the cage taken along line VI-VI in FIG. 5. [Figure 7] 7 is an enlarged cross-sectional view of the cage of FIG. 6 taken along line VII-VII in the circumferential direction. [Figure 8] 7 is an enlarged cross-sectional view of the cage of FIG. 6 taken along line VII-VII in the circumferential direction. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] As shown in FIG. 1, the wheel bearing device 1 rotatably supports a wheel in a suspension system of a vehicle such as an automobile. The 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 rolling rows of inner ball rows 5 and an outer ball row 6, an inner seal member 9 as a sealing member, and an outer seal member 10 as a sealing member. Here, in this specification, the "inner side" refers to the side of the wheel bearing device 1 that faces the vehicle body when the wheel bearing device 1 is mounted on the vehicle body, and the "outer side" refers to the side of the wheel when the wheel bearing device 1 is mounted on the vehicle body. In addition, the direction parallel to the rotation axis of the wheel bearing device 1 is referred to as the "axial direction," the direction perpendicular to the rotation axis of the wheel bearing device 1 is referred to as the "radial direction," and the direction along an arc centered on the rotation axis of the wheel bearing device 1 is referred to as the "circumferential direction." Additionally, the side away from the inside of the bearing along the rotation axis is referred to as the "axially outer side," and the side approaching the inside of the bearing along the rotation axis is referred to as the "axially inner side."

[0013] The outer ring 2 supports the hub ring 3 and the inner ring 4 via an inner ball row 5 and an outer ball row 6. The outer ring 2 is formed in a substantially cylindrical shape. An inner side opening 2a is formed at the inner side end of the outer ring 2, into which an inner side seal member 9 can be fitted. An outer side opening 2b is formed at the outer side end of the outer ring 2, into which an outer side seal member 10 can be fitted.

[0014] An inner-side outer raceway surface 2c and an outer-side outer raceway surface 2d are provided on the inner diameter surface of the outer ring 2. A vehicle body mounting flange 2e for mounting to a knuckle of a suspension system is integrally formed on the outer diameter surface of the outer ring 2.

[0015] The hub ring 3 supports a vehicle wheel for free rotation. The hub ring 3 is formed in a cylindrical shape. At the inner end of the hub ring 3, a small diameter step 3a is formed on the outer diameter surface, with a reduced diameter. At the outer end of the hub ring 3, a wheel mounting flange 3b for mounting a wheel is formed integrally. Hub bolts 3d are inserted into the wheel mounting flange 3b at positions evenly spaced around the circumference. The hub ring 3 is also arranged so that the outer inner raceway surface 3c faces the outer outer raceway surface 2d of the outer ring 2. An inner ring 4 is fitted into the small diameter step 3a of the hub ring 3.

[0016] The inner ring 4 applies preload to the inner ball row 5 and the outer ball row 6. An annular inner raceway 4a is formed in the circumferential direction on the outer diameter surface of the inner ring 4. The inner ring 4 is fixed to the inner end of the hub ring 3 by caulking. In other words, the inner raceway 4a is formed by the inner ring 4 on the inner side of the hub ring 3. The inner ring 4 is positioned so that its inner raceway 4a faces the outer raceway 2c on the inner side of the outer ring 2.

[0017] In the inner ball row 5 and the outer ball row 6, a plurality of balls 8, which are rolling elements, are held in an annular shape by a resin cage 7. The inner ball row 5 is rollably interposed between the inner raceway surface 4a of the inner ring 4 and the inner-side outer raceway surface 2c of the outer ring 2. The outer ball row 6 is rollably interposed between the inner raceway surface 3c of the hub ring 3 and the outer-side outer raceway surface 2d of the outer ring 2.

[0018] The cage 7 holds the balls 8. The cage 7 has an annular ring portion 7a and multiple pillar portions 7b. The pillar portions 7b extend axially outward from the ring portion 7a and are arranged at equal intervals around the circumference of the ring portion 7a. Pockets Pt that independently hold the balls 8 are formed at equal intervals between adjacent pillar portions 7b in the cage 7 (see FIG. 3). The pockets Pt have a pocket curved surface, which is a curved surface formed by the ring portion 7a and the adjacent pillar portions 7b so as to fit along the outer circumferential surface of the balls 8. The pocket curved surface is composed of an axially inner curved surface 7g and an axially outer curved surface 7k, which will be described later (see FIG. 4).

[0019] The balls 8 are formed of steel balls made of high carbon chromium bearing steel SUJ2, etc. The plurality of balls 8 are rotatably held in pockets Pt of the cage 7.

[0020] The inner seal member 9 seals the gap between the inner opening 2a of the outer ring 2 and the inner ring 4. The inner seal member 9 is, for example, a two-side lip type pack seal in which two seal lips come into contact. The inner seal member 9 includes a substantially cylindrical seal plate and a substantially cylindrical slinger.

[0021] The outer seal member 10 seals the gap between the outer opening 2b of the outer ring 2 and the hub ring 3. The outer seal member 10 has a core metal formed into a substantially cylindrical shape from a steel plate made of the same material as the seal plate, and multiple seal lips made of synthetic rubber such as NBR (acrylonitrile-butadiene rubber) are fixed to the core metal.

[0022] Hereinafter, a cage 7, which is one embodiment of a cage for a bearing device according to the present invention, will be described in detail with reference to FIGS.

[0023] As shown in FIG. 2, the annular portion 7a is located axially inward of the center of curvature P of the pocket curved surface. As shown in FIG. 6, the outer diameter surface 7c of the column portion 7b extends from the outer diameter surface 7d of the annular portion 7a at an incline toward the outer diameter side, and then extends axially from the inclined portion. The inner diameter surface 7e of the column portion 7b extends axially from the inner diameter surface 7f of the annular portion 7a at an incline toward the outer diameter side from the axially extending portion. The center of curvature P of the pocket curved surface is located at the same position as the center of the ball 8. One method for determining the center of curvature P of the pocket curved surface is to measure the curved surface using a three-dimensional coordinate measuring machine (CMM), create a virtual spherical surface based on the measured curved surface, and then determine the center of curvature P. This CMM may be a contact type or a non-contact type.

[0024] As shown in Figures 3 and 4, on the inner diameter side of the center position P of curvature of the pocket curved surface, the axially inner curved surface 7g, which is the pocket curved surface, is formed in a spherical shape with the annular portion 7a as its base. The axially inner curved surface 7g is composed of the annular portions 7a on the opposing side surfaces of adjacent column portions 7b and the annular portion 7a between them, and has a spherical shape that follows the outer peripheral surface of the ball 8. In addition, the column portions 7b are formed with an axially inner flat surface 7h that is linear and extends in the axial direction from the axially outer edge of the axially inner curved surface 7g toward the axially outer side (tip side) of the column portions 7b. The axially inner flat surface 7h is configured to guide the ball 8 from the tip of the column portions 7b into the space surrounded by the axially inner curved surface 7g.

[0025] On the outer diameter side of the center position P of curvature of the pocket curved surface, an axially outer flat surface 7j is formed in a linear shape extending in the axial direction. The axially outer flat surface 7j is located on the outer diameter side of the axially inner curved surface 7g. Furthermore, in the column portion 7b, an axially outer curved surface 7k, which is a pocket curved surface, is formed in a spherical shape extending from the axially outer edge of the axially outer flat surface 7j toward the axially outer side (tip side) of the column portion 7b. The axially outer curved surface 7k is located on the outer diameter side of the axially inner flat surface 7h and has a spherical shape that fits along the outer peripheral surfaces of the balls 8. In the cage 7 configured in this manner, pockets Pt that hold the balls 8 with the axially inner curved surface 7g and the axially outer curved surface 7k are formed at equal intervals between adjacent column portions 7b.

[0026] 5, the balls 8 contact the axially inner curved surface 7g and the axially outer curved surface 7k, thereby restricting the minimum distance between adjacent balls 8 on the pitch circle PCD. The thickness of the column portion 7b is thinnest on the pitch circle PCD and gradually increases with increasing distance from that point toward the inner diameter side and the outer diameter side.

[0027] The axially inner curved surface 7g is curved with its base at approximately the center of the adjacent column portions 7b. The spacing between adjacent column portions 7b is formed so that the spacing Wi between their inner diameter side ends and the spacing Wo between their outer diameter side ends are smaller than the spacing Wc between their approximate radial centers. This allows the column portions 7b to restrict the movement of balls 8 disposed inside the pocket Pt toward the inner diameter side and the outer diameter side.

[0028] The cage 7 is an injection-molded resin body. The cage 7 is formed by injecting resin into a mold (injection mold) during injection molding. The cage 7 is molded using a mold that molds the inner diameter side relative to the center position P of curvature of the pocket curved surface, and a mold that molds the outer diameter side relative to the center position P of curvature of the pocket curved surface. As shown in FIG. 7, the axially inner flat surface 7h is formed linearly in the axial direction. Therefore, when the inner diameter side mold 11 is removed, the mold 11 can be removed axially outward along the axially inner flat surface 7h (see arrow B). Similarly, when the outer diameter side mold is removed, the mold can be removed axially inward along the axially outer flat surface 7j.

[0029] As shown in Fig. 8, the axially inner flat surface 7h is formed linearly in the axial direction. On the other hand, the balls 8 are configured such that the outer peripheral surfaces of the balls 8 are spaced apart from the axially inner flat surface 7h toward the axially outer side (tip side) of the column portion 7b. As a result, a gap is formed between the axially inner flat surface 7h and the balls 8 in the cage 7, and the grease sealed on the axially outer side (seal member side) inside the bearing easily flows into the gap (see arrow C). The kinematic viscosity of the base oil of the grease is, for example, 10 to 200 mm at 40°C. 2 / s.

[0030] The cage 7 configured as described above can prevent deformation and damage to the column portions 7b when released from the mold, and allows grease to easily flow around the balls 8 when the bearing is rotating. Furthermore, because deformation of the column portions 7b when released from the mold can be prevented, the formability of the cage 7 is improved and the circumferential thickness of the column portions 7b can be made thinner than before. This makes it possible to increase the number of balls that can be incorporated into the cage 7. Furthermore, because the axially inner curved surface 7g and the axially outer curved surface 7k are spherical, the balls 8 incorporated into the cage 7 are prevented from falling out, and the retention of the balls 8 can be maintained.

[0031] 3 and 4, the cage 7 has a parting line PL formed therein, which is the portion where the inner diameter side mold and the outer diameter side mold come together during injection molding. The parting line PL is formed on an extension line of the outer diameter surface 7d of the annular portion 7a at the outer diameter side end of the axially inner flat surface 7h and the inner diameter side end of the axially outer flat surface 7j. The parting line PL at the outer diameter side end of the axially inner flat surface 7h is formed within the pocket Pt.

[0032] According to the retainer 7 configured as described above, when the inner diameter side mold and the outer diameter side mold that meet at the parting line PL are removed, the inner diameter side mold is removed axially outward and the outer diameter side mold is removed axially inward, thereby preventing deformation and damage to the column portion 7b.

[0033] As shown in Fig. 5, for the cage 7, when the radius of curvature diameter of the outer diameter of the ball 8 is D1 and the radius of curvature diameter of the pocket surface is D2, D1 < D2, and the difference between D1 and D2 is 0.05 to 0.5 mm. Also, the cage 7 is formed by adding glass fiber as a reinforcing material to polyamide 66, which is a synthetic resin excellent in oil resistance, wear resistance, and lubricity under the use conditions.

[0034] According to the cage 7 configured as described above, it is possible to prevent the grease from flowing around the ball 8 more than necessary. Also, if the difference in the radius of curvature diameters between D1 and D2 is too small, the pocket Pt inhibits the rotation of the ball 8, and if the difference in the radius of curvature diameters between D1 and D2 is too large, play of the ball 8 occurs in the pocket Pt and the holding performance of the ball 8 deteriorates. However, by setting the difference in the radius of curvature diameters between D1 and D2 to 0.05 to 0.5 mm as described above, the difference in the radius of curvature diameters between D1 and D2 is optimized.

[0035] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to such embodiments at all, and is merely illustrative. It is needless to say that the present invention can be implemented in various other forms without departing from the gist of the present invention. The scope of the present invention is shown by the description in the claims, and further includes the equivalent meaning described in the claims and all modifications within the scope. Also, in the present embodiment, the wheel bearing device 1 is configured as a third-generation structure wheel bearing device in which the inner raceway surface 3c is directly formed on the outer periphery of the hub ring 3, but is not limited thereto, and may be 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 ball bearing is fitted between the knuckle and the hub ring.

Explanation of Reference Numerals

[0036] 1 Wheel bearing device 2 Outer ring (outer member) 2c Outer raceway surface 2d Outer raceway surface 3 Hub ring (inner member) <00总字数=10150000158>3c Inner raceway surface 4 Inner ring (inner member) 4a Inner raceway surface 5 Inner ball row 6 Outer ball row 7 Cage 7a Annular part 7b Pillar part 7g Axial inner curved surface (pocket curved surface) 7h Axial inner plane 7j Axial outer plane 7k Axial outer curved surface (pocket curved surface) 11 Mold (injection mold) P: Center of curvature of pocket surface PL parting line Pt Pocket

Claims

1. a ring portion formed in an annular shape; a plurality of pillar portions extending axially outward from the annular portion at regular intervals in the circumferential direction; a pocket having a curved pocket surface that is a curved surface formed by adjacent column portions and annular portions so as to fit along an outer peripheral surface of the ball, the pocket holding the ball, The column portion is On the outer diameter side with respect to the center of curvature of the pocket curved surface, the axially inner side has a linear shape extending in the axial direction, On the inner diameter side with respect to the center of curvature of the pocket curved surface, the axially outer side has a linear shape extending in the axial direction, a parting line of the injection molding die is formed on an extension line of the outer diameter surface of the annular portion; A cage for a bearing device characterized in that:

2. A parting line of the injection molding mold is formed within the pocket.

2. The cage for a bearing device according to claim 1.

3. the diameter of curvature of the pocket curved surface is larger than the diameter of curvature of the outer diameter of the ball, the difference between the diameter of curvature of the outer diameter of the ball and the diameter of curvature of the pocket curved surface is 0.05 to 0.5 mm; 3. The cage for a bearing device according to claim 1 or 2.

4. It is made of polyamide 66 with glass fiber added. The cage for a bearing device according to any one of claims 1 to 3.

5. an outer member having a double-row outer raceway surface formed on an inner periphery thereof; an inner member having a double-row inner raceway surface formed thereon opposite to the double-row outer raceway surface; double rows of balls rollably interposed between the raceway surfaces of the outer member and the inner member; a retainer for retaining the interposed balls, The cage is a cage for a bearing device according to any one of claims 1 to 4. A wheel bearing device characterized in that:

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