Crowned cage for bearing, and rolling bearing

Abstract

To provide a crowned cage for bearing that has superior lubricity in a packet, and a rolling bearing.SOLUTION: A crowned cage for bearing comprises an annular main part, a plurality of column parts projecting from a top surface of the main part toward one axial side circumferentially at predetermined intervals, and a spherical pocket formed between circumferentially adjacent column parts and holding a rolling body. On the back face of the main part, a lightened part which is recessed toward one axial side is formed between circumferentially adjacent pockets. The lightened part has a back face-side opening part communicating with the back face of the main part and a pocket-side opening part communicating with pockets on both circumferential sides of the lightened part. The one-axial-side end part of the pocket-side opening part of the lightened part is located at the axially same position with the one-axial-side end part of a circumferential center part of the lightened part, or on one axial side with respect to the one-axial-side end part of a circumferential center part of the lightened part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a crown type cage for a bearing and a rolling bearing. [Background technology]

[0002] Generally, rolling bearings are used to support the rotating parts of various rotating machines. With the recent trend towards electric vehicles, there is a demand for higher speeds in the rolling bearings (especially ball bearings) that support the rotating shaft of the motor. To achieve higher speeds, it is necessary to prevent fatigue failure by suppressing the centrifugal expansion of the cage and reducing the stress generated at the bottom of the pocket.

[0003] Patent Document 1 discloses a cage used in a rolling bearing for a hybrid vehicle drive motor. This cage employs a configuration in which the outer diameter of multiple elastic pieces arranged at multiple circumferential positions on one axial side of the annular main part is smaller than the outer diameter of the annular main part, or a configuration in which a notch is provided on the outer diameter surface of the elastic pieces, or a configuration in which the elastic pieces are formed in a tapered shape that slopes downward toward their free ends, thereby reducing the weight of the free end of the cage and reducing centrifugal force, and also avoiding contact with the outer ring, etc., even when deformation occurs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-329045 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to achieve even higher rotation speeds of rolling bearings, it is important to maintain an appropriate lubrication state between the rolling elements and the inner surface of the cage pocket. However, in rolling bearings using a cage made of synthetic resin, the cage occupies a considerable amount of space in the annular space between the inner and outer rings. Therefore, the flow of lubricant such as grease sealed in the annular space is hindered by the cage, and as a result, it becomes difficult for the lubricant to be supplied to the inside of the cage pocket.

[0006] In particular, in the cage described in Patent Document 1, the radial width of the elastic pieces is set smaller than the radial width of the main part, so the radial width of the pockets formed by adjacent elastic pieces in the circumferential direction is also smaller than usual. As a result, the area of ​​the inner surface of the pockets that hold the rolling elements is reduced, and the amount of grease that can be held is reduced, which may lead to seizure due to grease depletion.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crown type cage for a bearing and a rolling bearing which have excellent lubrication inside the pocket. [Means for solving the problem]

[0008] The above object of the present invention can be achieved by the following configuration. (1) a circular main portion; A plurality of pillar portions protruding from an upper surface of the main portion on one axial side at predetermined intervals in a circumferential direction to one axial side; a plurality of pockets formed between the column portions adjacent to each other in the circumferential direction, each of which is capable of holding a rolling element; A crown type cage for a bearing, comprising: The pillar portion has a pair of claw portions whose tip portions are spaced apart from each other, and a connection portion that connects the pair of claw portions, The radial width t1 of the claw portion is smaller than the radial width t2 of the main portion, A lightening hole is formed in the main portion between adjacent pockets in the circumferential direction, the lightening hole penetrating from the upper surface on one axial side to the lower surface on the other axial side, The recess has an upper surface side opening communicating with the upper surface of the main portion, a lower surface side opening communicating with the lower surface of the main portion, and a pocket side opening communicating with the pockets on both circumferential sides of the recess. 1. A crown type cage for a bearing, comprising: (2) an outer ring; With the inner circle, A plurality of rolling elements disposed between the outer ring and the inner ring; (1) A bearing cage having a crown type; A rolling bearing comprising: Effect of the Invention

[0009] According to the crown type cage for bearing and the rolling bearing of the present invention, the lubrication inside the pocket can be improved. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a ball bearing according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view of the cage according to the first embodiment. [Diagram 3] FIG. 3 is a perspective view of a portion of the cage according to the first embodiment. [Figure 4] FIG. 4 is a view of a part of the cage according to the first embodiment as viewed from the radial outside. [Diagram 5] FIG. 5 is a view of a part of the cage according to the first embodiment, as viewed from one axial side. [Figure 6] FIG. 6 is a view of a part of the cage according to the first embodiment, as viewed from the other axial side. [Figure 7] FIG. 7 is a diagram showing the balls and lubricant in FIG. [Figure 8] FIG. 8 is a diagram showing the balls and lubricant in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A crown type cage for a bearing and a rolling bearing according to an embodiment of the present invention will be described below with reference to the drawings.

[0012] FIG. 1 is a cross-sectional view of a ball bearing according to the first embodiment. FIG. 2 is a perspective view of a cage according to the first embodiment. FIG. 3 is a perspective view of a portion of the cage according to the first embodiment. FIG. 4 is a view of a portion of the cage according to the first embodiment, seen from the radial outside. FIG. 5 is a view of a portion of the cage according to the first embodiment, seen from one axial side. FIG. 6 is a view of a portion of the cage according to the first embodiment, seen from the other axial side. In FIGS. 1 to 4, one axial side is indicated by arrow A, and the other axial side is indicated by arrow B.

[0013] 1, ball bearing (rolling bearing) 1 includes an inner ring 3 having an inner ring raceway 2 on its outer peripheral surface, an outer ring 5 having an outer ring raceway 4 on its inner peripheral surface, balls 6 which are multiple rolling elements arranged between the inner ring raceway 2 and the outer ring raceway 4, a pair of seals 7 fixed to both axial ends of the inner peripheral surface of the outer ring 5 and which seal the bearing internal space between the inner ring 3 and the outer ring 5, and a bearing crown cage (hereinafter also referred to as a "crown cage" or simply a "cage") 10 which holds the multiple balls 6 so that they can roll freely. A lubricant such as grease is filled in the ball bearing 1.

[0014] The crown type cage 10 is made of a resin material such as polyamide 6 (PA6), polyamide 6,6 (PA66), polyamide 46 (PA46), polyamide 9T (PA9T), polyamide 10T (PA10T), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), or other resin material. In order to improve the strength of the cage 10, the cage may be a resin composition to which 5 to 50 wt % of a fibrous reinforcing material (glass fiber, carbon fiber, aramid fiber, cellulose nanofiber, etc.) is added. Examples of a method for manufacturing the cage 10 include an injection molding method using a mold and a manufacturing method using a 3D printer.

[0015] Referring also to Figures 2 to 6, the retainer 10 comprises a circular annular main portion 20, a plurality of pillar portions 30 protruding axially at predetermined intervals circumferentially from an upper surface 21 on one axial side of the main portion 20, and a spherically shaped pocket 40 formed between adjacent pillar portions 30, 30 and capable of holding balls 6.

[0016] A plurality of spherical concave surfaces 23 are formed at predetermined intervals in the circumferential direction on the upper surface 21 of the main portion 20. The concave surfaces 23 are formed across the entire radial width of the main portion 20 and define pockets 40.

[0017] As described later, a lightening hole 50 is provided in the radial center of the main portion 20 between circumferentially adjacent pockets 40, so that the main portion 20 is divided into two radial portions sandwiched between the lightening hole 50. Of the main portion 20, the one disposed on the radially inner side is sometimes referred to as an inner main portion 20A, and the one disposed on the radially outer side is sometimes referred to as an outer main portion 20B.

[0018] The pillar portion 30 has a pair of claw portions 31, 31 and a connection portion 33 that connects the pair of claw portions 31, 31.

[0019] The column portion 30 protrudes axially from the radially inner side of the upper surface 21 of the main portion 20 toward one axial side. In other words, the column portion 30 protrudes axially from the upper surface of the inner main portion 20A. The column portion 30 is not formed on the upper surface of the outer main portion 20B. Therefore, the upper surface 21 of the main portion 20 (the upper surface of the outer main portion 20B) is exposed on the radially outer side of the column portion 30. In a conventional crown type cage, it is normal for the column portion to protrude axially from the entire radial width of the upper surface of the main portion, and the column portion 30 of the present embodiment is different in this regard. That is, in the present embodiment, a configuration is adopted in which the column portion 30 (claw portion 31) is provided only on the inner main portion 20A, and the column portion 30 (claw portion 31) is not provided on the outer main portion 20B. Since the plurality of pockets 40 are connected by the main portion 20, when a centrifugal force is applied to the cage 10 during high-speed rotation or the like, the cage 10 tends to fall radially outward about the main portion 20. In order to suppress this fall, as described above, the column portion 30 (claw portion 31) is provided only on the inner main portion 20A, and the column portion 30 (claw portion 31) is not provided on the outer main portion 20B. Further, even if the cage 10 falls, contact with the outer ring 5 is avoided.

[0020] As described above, in the present embodiment, as shown in FIG. 1, the radial width t1 of the claw portion 31 is set smaller than the radial width t2 of the main portion 20 (t1 < t2). In order to cope with high-speed rotation, from the viewpoint of reducing the weight of the claw portion 31, the radial width t1 of the claw portion 31 is preferably 2 / 3 or less of the radial width t2 of the main portion 20 (t1 ≦ t2 × 2 / 3), and more preferably 1 / 2 or less (t1 ≦ t2 × 1 / 2).

[0021] Assuming that the centrifugal force is F, the mass is m, the distance from the rotation axis to the rotating object (cage 10) is r, and the angular velocity is ω, then F = mrω 2The stress σ generated in the cage 10 (particularly the bottom of the pocket 40) and the amount of deformation δ of the cage 10 are approximately proportional to the centrifugal force F. Therefore, when the axial width of the ball bearing 1, the inner diameter of the inner ring 3, and the outer diameter of the outer ring 5 are constant, the mass m of the cage 10 must be reduced in order to reduce the stress σ and the amount of deformation δ. Furthermore, since the amount of deformation δ of the cage 10 is approximately inversely proportional to the rigidity of the cage 10, the rigidity of the cage 10, i.e., the Young's modulus, may be increased when the shape of the cage 10 does not change.

[0022] In the illustrated example, the pillar portion 30 (claw portion 31) is provided on the upper surface of the inner main portion 20A, so that the outer diameter of the pillar portion 30 (claw portion 31) is set smaller than the outer diameter of the main portion 20, but this is not limiting, and the pillar portion 30 (claw portion 31) may be provided on the upper surface of the outer main portion 20B, so that the inner diameter of the pillar portion 30 (claw portion 31) is set larger than the inner diameter of the main portion 20. In this case, the pillar portion 30 (claw portion 31) is provided only on the outer main portion 20B, and the pillar portion 30 (claw portion 31) is not provided on the inner main portion 20A.

[0023] The tip ends 31A, 31A of the pair of claws 31, 31 are arranged at a distance from each other in the circumferential direction. In addition, between the tip ends 31A, 31A of the two adjacent claws 31, 31 constituting the pocket 40, an inlet portion 41 having a width smaller than the diameter of the ball 6 and for inserting the ball 6 is provided.

[0024] Although the specification explains for convenience that "balls 6 are inserted into pockets 40 of retainer 10," more accurately, rather than inserting balls 6 into each pocket 40 of retainer 10, retainer 10 is assembled into ball bearing 1 by fitting retainer 10 onto multiple balls 6 arranged between inner ring 3 and outer ring 5 of ball bearing 1.

[0025] The claw portion 31 has a spherical first circumferential surface 31B that constitutes the pocket 40, and a second circumferential surface 31C opposite to the first circumferential surface 31B.

[0026] The second circumferential surfaces 31C, 31C of the pair of claws 31, 31 are each curved and smoothly connected to each other at the upper surface 33A of the connection portion 33. The upper surface 33A of the connection portion 33 corresponds to the bottom of the substantially U-shaped shape formed by the pair of second circumferential surfaces 31C, 31C. The upper surface 33A of the connection portion 33 (the bottom of the pair of second circumferential surfaces 31C, 31C) is located slightly above (one axial side) the upper surface 21 of the main portion 20 (see Figs. 3 and 4). Therefore, the bottoms (the upper surfaces 33A of the connection portions 33) of the pair of second circumferential surfaces 31C, 31C are located relatively below (the other axial side), forming a substantially U-shaped recess. More specifically, the upper surface 33A of the connection portion 33 is located below (the other axial side) the center of the ball 6 inserted into the pocket 40 (pocket center). 4, the center position of the balls 6 is indicated by a dashed line a, and the upper surface 33A of the connection portion 33 is located below this dashed line a. In this manner, in this embodiment, a configuration is adopted in which the bottom surface of the area sandwiched between the pair of second circumferential surfaces 31C, 31C of the pair of claw portions 31, 31 is located below the center of the pocket, thereby achieving weight reduction. In conventional crown type cages, the upper surface of the connection portion (the bottom surface of the pair of second circumferential surfaces) is usually located above the center of the balls inserted in the pocket (the center of the pocket).

[0027] The first circumferential surfaces 31B, 31B of two adjacent claw portions 31, 31 and the concave surface 23 of the main portion 20 form a pocket 40. These two first circumferential surfaces 31B, 31B and the concave surface 23 are smoothly connected to each other and form a spherical concave surface of the pocket 40. The radius of curvature of the spherical concave surface of the pocket 40 is set to be larger than the radius of curvature of the rolling surfaces of the balls 6.

[0028] According to the cage 10 of this embodiment, the claws 31 are formed thin in the radial and circumferential directions, so that the cage 10 is lighter and the effect of centrifugal force during rotation can be reduced, thereby suppressing deformation. Therefore, the cage 10 can be prevented from contacting the outer ring 5, the seal 7, etc., and wear, vibration, and heat generation of the cage 10 can be suppressed.

[0029] In the main portion 20, a lightening hole 50 is formed between circumferentially adjacent pockets 40, penetrating from the upper surface 21 on one axial side to the lower surface 25 on the other axial side. The lightening hole 50 is formed in the radial center between the inner main portion 20A and the outer main portion 20B of the main portion 20.

[0030] The lightening hole 50 has an upper surface side opening 51 that communicates with the upper surface 21 of the main portion 20 and opens to one side in the axial direction, a lower surface side opening 53 that communicates with the lower surface 25 of the main portion 20 and opens to the other side in the axial direction, and a pocket side opening 55 that opens in the circumferential direction and communicates with the pockets 40 on both circumferential sides of the lightening hole 50. The other axial side end d of the pocket side opening 55 and the circumferential end e of the lower surface side opening 53 are connected by a wall surface 57.

[0031] The lightening hole 50 is disposed so as not to overlap with the bottom part at the circumferential center of the pocket 40 (the part where the axial thickness of the main portion 20 is smallest) in the circumferential direction. In Fig. 4, the circumferential end part of the lower surface opening 53 on the pocket 40 side (the circumferential end part of the pocket 40 in the illustrated example) is indicated by the symbol e.

[0032] The pocket side opening 55 is formed along the concave surface 23 of the main portion 20 that constitutes the pocket 40, and has a partially spherical shape. In Fig. 4, the other axial end of the pocket side opening 55 is indicated by the symbol d, and the one axial end of the pocket side opening 55 is indicated by the symbol c. The other axial end d of the pocket side opening 55 is connected to wall surfaces 57 on both circumferential sides (pocket 40 sides) of the lightening hole 50. The one axial end c of the pocket side opening 55 is connected to the upper surface opening 51.

[0033] 4, one axial end of the circumferential center of the recess 50 (the circumferential center position between adjacent pockets 40, 40) is indicated by the symbol b. The symbol b also indicates the circumferential center of the upper surface opening 51 of the recess 50.

[0034] Note that the one axial end c of the pocket side opening 55 is also the circumferential end of the top surface side opening 51. Therefore, a plane connecting the circumferential center b of the top surface side opening 51 and the one axial end c of the pocket side opening 70 becomes the top surface side opening 51. In this embodiment, the circumferential center b and the one axial end c are at the same position in the axial direction, but they do not necessarily have to be at the same position.

[0035] 4, the central position (pocket center) in the axial direction of the ball 6 inserted in the pocket 40 is indicated by a dashed line a. The upper surface opening 51, which is the end portion on one side in the axial direction of the recess 50, is located on the other side in the axial direction of the central position a of the ball 6 inserted in the pocket 40.

[0036] Because the pockets 40 of the crown cage 10 are forcibly removed during molding, if the pockets 40 were to be removed from the center position a of the balls 6 (pocket center) to one side in the axial direction, the mold for the pockets 40 and the mold for the recesses 50 would interfere with each other. To prevent such interference between the molds, the end of the one axial side of the recesses 50 is positioned to be on the other axial side of the center position a of the balls 6 (pocket center), preventing the depth of the recesses 50 from becoming too large.

[0037] Furthermore, a wall surface 57 is erected in the axial direction between the other axial end d of the pocket side opening 55 of the lightening hole 50 and the circumferential end (the end on the pocket 40 side) e of the lower surface side opening 53. The distance de (axial length of the wall surface 57) between the other axial end d and the circumferential end e is preferably greater than the circumferential thickness f of the claw portion 31. Note that the circumferential thickness f of the claw portion 31 means the circumferential thickness of the claw portion 31 at the pocket center position a. By making the distance de greater than the circumferential thickness f, the thickness of the pocket bottom can be made thicker than the claw portion 31, and the strength of the cage 10 can be increased.

[0038] In the illustrated example, the wall surface 57 has a planar shape extending perpendicular to the circumferential direction (parallel to the axial and radial directions), but in consideration of the stamping out of the cage 10, it is preferable to incline the wall surface 57 by about 2° or more toward the column portion 30. In other words, the other axial end portion d may be disposed closer to the column portion 30 than the circumferential end portion e. However, if the wall surface 57 has a curved shape rather than a planar shape, it will hinder the lubricant that has entered the lightening hole 50 from the lower surface 25 from reaching the pocket side opening 55, which is not preferable.

[0039] FIG. 7 is a diagram showing the balls 6 and the lubricant G in FIG. 4. FIG. 8 is a diagram showing the balls 6 and the lubricant G in FIG. 5. As shown in FIG. 7 and FIG. 8, the lubricant G that enters the hollow 50 from the lower surface 25 is guided by the wall surface 57 and reaches the pocket side opening 55. Then, as the retainer 10 rotates, the lubricant G near the pocket side opening 55 is supplied to the bottom surface of the pocket 40. For example, when the retainer 10 rotates clockwise in the direction shown by the arrow C in FIG. 8 (from the right side to the left side in FIG. 8), the lubricant G near the pocket side opening 55 on the left side of FIG. 8 is guided counterclockwise to the right and supplied to the bottom surface of the pocket 40 by the rotation of the retainer 10. Conversely, when the retainer 10 rotates in the opposite direction to the arrow C in FIG. 8 (counterclockwise), the lubricant G near the pocket side opening 55 on the right side of FIG. 8 is guided clockwise to the left and supplied to the bottom surface of the pocket 40 by the rotation of the retainer 10. Furthermore, the lubricant G spreads along the balls 6 due to centrifugal force. Therefore, the bottom surface of the pocket 40 is kept well lubricated, and problems such as seizure caused by insufficient lubrication can be avoided, thereby extending the bearing life.

[0040] As described above, the present specification discloses the following configurations. (1) a circular main portion; A plurality of pillar portions protruding from an upper surface of the main portion on one axial side at predetermined intervals in a circumferential direction to one axial side; a plurality of pockets formed between the column portions adjacent to each other in the circumferential direction, each of which is capable of holding a rolling element; A crown type cage for a bearing, comprising: The pillar portion has a pair of claw portions whose tip portions are spaced apart from each other, and a connection portion that connects the pair of claw portions, The radial width t1 of the claw portion is smaller than the radial width t2 of the main portion, A lightening hole is formed in the main portion between adjacent pockets in the circumferential direction, the lightening hole penetrating from the upper surface on one axial side to the lower surface on the other axial side, The recess has an upper surface side opening communicating with the upper surface of the main portion, a lower surface side opening communicating with the lower surface of the main portion, and a pocket side opening communicating with the pockets on both circumferential sides of the recess. 1. A crown type cage for a bearing, comprising: (2) The radial width t1 of the claw portion is 2 / 3 or less of the radial width t2 of the main portion. A crown type cage for a bearing as described in (1). (3) An upper surface of the connection portion of the column portion on one axial side is located on the other axial side of the center of the rolling element inserted into the pocket. A crown cage for a bearing according to (1) or (2). (4) A distance between the other axial end of the pocket side opening of the hollow portion and the pocket side end of the lower surface side opening in the circumferential direction is greater than a circumferential thickness of the claw portion. The crown cage for a bearing according to any one of (1) to (3). (5) A wall surface is provided between the other axial end of the pocket side opening of the hollow portion and the pocket side end of the lower surface opening in the circumferential direction, The wall surface has a planar shape. The crown cage for a bearing according to any one of (1) to (4). (6) an outer ring; With the inner circle, A plurality of rolling elements disposed between the outer ring and the inner ring; A bearing cage according to any one of (1) to (5), A rolling bearing comprising: [Explanation of symbols]

[0041] 1. Ball bearings (rolling bearings) 2 Inner ring raceway surface 3. Inner Circle 4 Outer ring raceway 5 Outer ring 6 balls (rolling elements) 7 Seal 10 Crown cage for bearings 20 Main Section 20A Inner main part 20B Outer main part 21 Top side 23 Concave 25 Bottom side 30 Pillar section 31 Claw part 31A Tip 31B First circumferential surface 31C Second circumferential surface 33 Connection 33A Top 40 Pockets 41 Entrance 50 Meatless 51 Top side opening 53 Bottom side opening 55 Pocket side opening 57 Wall a) Center position of the ball (center of the pocket) b Circumferential center of the upper opening of the cutout c One axial end of the hollowed-out pocket opening d The other axial end of the hollowed-out pocket opening e Circumferential end of the lower opening of the cutout f Circumferential thickness of the claw t1 Radial width of the claw t2 Radial width of main part

Claims

1. A circular main portion; A plurality of pillar portions protruding from an upper surface of the main portion on one axial side at predetermined intervals in a circumferential direction to one axial side; a plurality of pockets formed between the column portions adjacent to each other in the circumferential direction, each of which is capable of holding a rolling element; A crown type cage for a bearing, comprising: The pillar portion has a pair of claw portions whose tip portions are spaced apart from each other, and a connection portion that connects the pair of claw portions, The radial width t1 of the claw portion is smaller than the radial width t2 of the main portion, A lightening hole is formed in the main portion between adjacent pockets in the circumferential direction, the lightening hole penetrating from the upper surface on one axial side to the lower surface on the other axial side, The recess has an upper surface side opening communicating with the upper surface of the main portion, a lower surface side opening communicating with the lower surface of the main portion, and a pocket side opening communicating with the pockets on both circumferential sides of the recess.

1. A crown type cage for a bearing, comprising:

2. The radial width t1 of the claw portion is 2 / 3 or less of the radial width t2 of the main portion.

2. The bearing cage according to claim 1 .

3. an upper surface of the connection portion of the column portion on one axial side is located on the other axial side of the center of the rolling element inserted into the pocket; 2. The bearing cage according to claim 1 .

4. a distance between the other axial end of the pocket side opening of the hollow portion and the pocket side end of the lower surface side opening in the circumferential direction is greater than a circumferential thickness of the claw portion; 2. The bearing cage according to claim 1 .

5. a wall surface is provided between the other axial end of the pocket side opening of the hollow portion and the pocket side end of the lower surface opening in the circumferential direction, The wall surface has a planar shape.

2. The bearing cage according to claim 1 .

6. The outer ring and With the inner circle, A plurality of rolling elements disposed between the outer ring and the inner ring; A bearing crown cage according to any one of claims 1 to 5, A rolling bearing comprising:

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