Ball bearings, or electric motors of electric vehicles.

Abstract

To provide a ball bearing for hardly causing the deformation of a resin cage due to centrifugal force when used with high speed rotation.SOLUTION: In a radial outside face 23 of a cage claw part 22, an outer diameter side axial groove 24 is formed. In a radial inside face 25 of the cage claw part 22, an inner diameter side axial groove 26 is formed. The cage claw part 22 has a sectional shape perpendicular to the axial direction formed as a H-shape opening radially outward and radially inward by the outer diameter side axial groove 24 and the inner diameter side axial groove 26.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This invention relates to ball bearings.

Background Art

[0002] As a bearing for supporting a rotating shaft of an automobile or an industrial machine, etc., ball bearings are widely used. Generally, a ball bearing has an inner ring, an outer ring provided coaxially on the radially outer side of the inner ring, a plurality of balls provided in an annular space between the inner ring and the outer ring, and a cage for holding the plurality of balls.

[0003] As the cage, for example, as in Patent Document 1, there is known a resin cage (so-called crown-shaped cage) having a cage annular portion extending in the circumferential direction adjacent to the ball passing region and a cantilever beam-shaped cage claw portion extending in the axial direction between circumferentially adjacent balls from the cage annular portion. The cage claw portion has a ball guide surface facing the surface of the ball, and this ball guide surface is a concave spherical surface along the surface of the ball so as to hold the ball.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, in the field of electric vehicles such as EVs (battery electric vehicles) and HEVs (hybrid electric vehicles), in order to reduce the size and weight of electric motors, the high-speed rotation of electric motors has been promoted. A ball bearing that supports a rotating shaft to which the rotation of such an electric motor is input may be used under the condition that the dmn value (pitch circle diameter dm (mm) of the ball × rotational speed n (min -1 )) exceeds 2 million.

[0006] The inventors of this invention considered using a crown-shaped cage in ball bearings that support high-speed rotating shafts in EVs, HEVs, and the like.

[0007] However, when using a crown-type cage in a high-speed rotating ball bearing, it has been found that the centrifugal force acting on the cantilever-shaped cage claws causes torsional deformation in the cage ring portion, tilting the cage claws radially outward, and also causes radially outward bending deformation in the cage claws themselves. These deformations may cause the cage claws to interfere with the balls. If the cage claws interfere with the balls, it can cause the ball bearing to overheat.

[0008] The problem that this invention aims to solve is to provide a ball bearing in which deformation of the resin cage due to centrifugal force is less likely to occur when used at high rotational speeds. [Means for solving the problem]

[0009] To solve the above problems, this invention employs the following configuration for the ball bearing. Insider, An outer ring is provided coaxially on the radially outer side of the inner ring, A plurality of balls are incorporated into the annular space formed between the inner ring and the outer ring, The system comprises a resin holder that holds the plurality of balls, The resin cage is a ball bearing having a cage annular portion extending circumferentially adjacent to the ball passage area and a cantilever-shaped cage claw portion extending axially between adjacent balls in the circumferential direction from the cage annular portion, On the radially outer surface of the retainer claw portion, an outer diameter axial groove is formed, extending axially from the tip of the retainer claw portion toward the retainer annular portion. An inner diameter axial groove is formed on the radially inner surface of the retainer claw portion, extending axially from the tip of the retainer claw portion toward the retainer annular portion. The ball bearing is characterized in that the retainer claw portion has an H-shape in which the cross-sectional shape perpendicular to the axial direction is open radially outward and radially inward due to the outer diameter side axial groove and the inner diameter side axial groove.

[0010] In this way, the outer diameter axial groove formed on the radially outer surface of the retainer claw and the inner diameter axial groove formed on the radially inner surface of the retainer claw result in an H-shaped cross-section of the retainer claw. This allows for a reduction in the mass of the retainer claw while ensuring a high second moment of area (resistance to deformation of the retainer claw against bending moment). Therefore, even when used at high rotational speeds, it is possible to suppress torsional deformation of the retainer ring due to the centrifugal force acting on the retainer claw, and also suppress radial outward deflection deformation of the retainer claw itself.

[0011] The axial length of the retainer claw portion is set to be greater than the radius of the ball. The retainer claw portion has a circumferentially opposing surface that faces the ball in the circumferential direction, It is preferable to adopt a configuration in which the portion of the circumferentially opposing surface that receives the ball in the circumferential direction has a planar shape that extends so as not to interfere with the ball when the retainer claw portion moves radially outward due to centrifugal force.

[0012] In this configuration, since the circumferentially opposing surfaces of the cage claws are planar, it is possible to prevent interference between the circumferentially opposing surfaces of the cage claws and the balls when the cage claws move radially outward due to the centrifugal force acting on them. Furthermore, since the shear resistance of the lubricant between the circumferentially opposing surfaces of the cage claws and the balls is kept low, it is also possible to suppress heat generation in the ball bearing.

[0013] The retainer ring portion has an axially opposing surface that faces the ball in the axial direction, It is preferable to adopt a configuration in which the circumferentially opposing surface and the axially opposing surface are connected in a concave arc shape in cross-section.

[0014] By doing so, since the circumferential opposing surface and the axial opposing surface are connected in a cross-sectional concave arc shape, it is possible to secure the cross-sectional area of the root portion in the axial direction of the cage claw portion while suppressing the mass of the tip portion in the axial direction of the cage claw portion to a small value. Therefore, it becomes possible to effectively suppress the deflection of the cage claw portion due to the centrifugal force acting on the cage claw portion.

[0015] It is preferable to adopt a configuration in which the axial end portion of the outer diameter side axial groove closer to the cage ring portion is cut and raised in a cross-sectional concave arc shape on the outer circumference of the cage ring portion.

[0016] By doing so, since the axial end portion of the outer diameter side axial groove closer to the cage ring portion is cut and raised in a cross-sectional concave arc shape, it is possible to secure the cross-sectional area of the root portion in the axial direction of the cage claw portion while suppressing the mass of the tip portion in the axial direction of the cage claw portion to a small value. Therefore, it becomes possible to effectively suppress the deflection of the cage claw portion due to the centrifugal force acting on the cage claw portion.

[0017] It is preferable to form a cage guided surface on the inner circumference of the cage ring portion that is slidably guided by sliding contact with the outer circumference of the inner ring.

[0018] By doing so, the resin cage can be positioned in the radial direction by the sliding contact between the cage guided surface on the inner circumference of the cage ring portion and the outer circumference of the inner ring.

[0019] It further has an annular seal member that closes one end opening in the axial direction of the annular space, the cage ring portion has a cage side sliding contact surface that slidably contacts the seal member in the axial direction, the seal member has a seal side sliding contact surface that slidably contacts the cage side sliding contact surface, It is preferable to adopt a configuration in which a plurality of axial protrusions having an arc shape convex in the axial direction in the cross-sectional shape along the circumferential direction are formed at a constant pitch in the circumferential direction on one of the sliding contact surfaces of the cage side sliding contact surface and the seal side sliding contact surface.

[0020] By doing so, on one of the sliding contact surfaces of the cage-side sliding contact surface and the seal-side sliding contact surface, a plurality of axial protrusions having an arc shape convex in the axial direction in the cross-sectional shape along the circumferential direction are formed at a constant pitch in the circumferential direction. Therefore, an oil film due to the wedge film effect is formed between the axial protrusions and the sliding contact surface, and the space between the axial protrusions and the sliding contact surface becomes a fluid lubrication state due to the oil film, and the contact resistance between the cage and the seal member can be suppressed to be extremely small. Therefore, it is possible to prevent abnormal heat generation due to the sliding resistance of the contact portion between the cage and the seal member. Further, since the cage annular portion is provided in sliding contact with the seal member, the axial thickness of the cage annular portion can be set large, and the rigidity of the cage annular portion can be increased. Therefore, even when used at high speed rotation, it is possible to suppress the torsional deformation of the cage annular portion due to the centrifugal force received by the cage claw portion, and it is possible to suppress the cage claw portion from tilting radially outward.

[0021] It is preferable to adopt a configuration in which the axial protrusion has a flat top portion with a constant height in the radial direction at the top of the arc shape convex in the axial direction in the cross-section along the circumferential direction, and an inclined top portion in which the height of the top of the arc shape convex in the axial direction in the cross-section along the circumferential direction gradually decreases radially outward from the radially outer end of the flat top portion.

[0022] By doing so, when the bearing rotates at a low speed and the centrifugal force received by the cage claw portion is relatively small, an oil film due to the wedge film effect can be formed between the flat top portion of the axial protrusion and the sliding contact surface. Further, when the bearing rotates at a high speed and the centrifugal force received by the cage claw portion is relatively large, an oil film due to the wedge film effect can be formed between the flat top portion and the inclined top portion of the axial protrusion and the sliding contact surface in a state where the cage annular portion has a relatively large torsional deformation. Thus, it is possible to stably form an oil film due to the wedge film effect between the cage and the seal member regardless of the rotation speed of the bearing.

[0023] It is preferable that the inclined top portion has an R shape in the cross-sectional shape orthogonal to the circumferential direction and is smoothly connected to the flat top portion.

[0024] In this configuration, the inclined apex and the parallel apex are smoothly connected, making it possible to stably form an oil film between the parallel and inclined apex and the sliding surface due to the wedge effect, even when the retainer ring undergoes relatively large torsional deformation.

[0025] It is preferable that the plurality of axial protrusions be positioned so as to overlap with the pitch circle of the ball or radially outward from there.

[0026] In this way, when centrifugal force acting on the retainer claws causes torsional deformation in the retainer ring portion that tilts the retainer claws radially outward, it is possible to prevent the retainer-side sliding contact surface and the seal-side sliding contact surface from coming into contact at a position radially outward from the axial projection due to this torsional deformation.

[0027] It is preferable that the outer diameter axial groove has a shape in which the position of the groove bottom gradually changes radially outward from the tip side of the retainer claw portion toward the retainer annular portion.

[0028] In this manner, the position of the groove bottom of the outer diameter axial groove gradually changes radially outward from the tip of the retainer claw towards the retainer ring. As a result, the lubricant supplied into the outer diameter axial groove moves from the tip of the retainer claw towards the retainer ring due to the pumping action and is introduced into the region between the retainer ring and the sealing member. Therefore, it becomes possible to sufficiently lubricate the space between one of the sliding surfaces (the retainer side sliding surface or the sealing side sliding surface) and the axial projection, effectively forming an oil film with a wedge-shaped film.

[0029] Furthermore, the inner diameter axial groove can be of a shape in which the position of the groove bottom gradually changes radially inward from the tip of the retainer claw portion towards the retainer annular portion.

[0030] It is preferable to adopt a configuration in which the axial end of the annular space opposite to the axial end that is sealed by the sealing member is left open without a sealing member, so as to allow lubricant supplied from the outside to be received into the annular space.

[0031] In this way, it is possible to adequately lubricate the space between one of the sliding surfaces (the retainer side sliding surface or the seal side sliding surface) and the axial projection, thereby reliably forming an oil film with a wedge-shaped film.

[0032] The ball bearing described above is particularly suitable for use as a bearing in an electric motor of an electric vehicle or as a bearing in an electric vehicle transmission that reduces the rotation of the electric motor. [Effects of the Invention]

[0033] In this ball bearing, the cross-sectional shape of the cage claws is H-shaped due to the outer diameter axial groove formed on the radially outer surface of the cage claws and the inner diameter axial groove formed on the radially inner surface of the cage claws. This allows for a reduction in the mass of the cage claws while ensuring a high second moment of area (resistance to deformation of the cage claws against bending moment). Therefore, even when used at high rotational speeds, torsional deformation of the cage ring due to centrifugal force acting on the cage claws is suppressed, and deflection deformation of the cage claws themselves radially outward is also suppressed. [Brief explanation of the drawing]

[0034] [Figure 1] Cross-sectional view showing a ball bearing according to a reference embodiment of this invention. [Figure 2] Cross-sectional view along line II-II in Figure 1 [Figure 3] Cross-sectional view along line III-III in Figure 1 [Figure 4] Enlarged cross-sectional view of the vicinity of the resin cage of the ball bearing in Figure 1. [Figure 5] Figure 1 is a perspective view of the retainer, seen from the side of the retainer claws. [Figure 6] Figure 1 shows a magnified view of the vicinity of the seal lip of the sealing member. [Figure 7] Cross-sectional view along line VII-VII in Figure 6 [Figure 8] Schematic diagram of an electric vehicle transmission incorporating ball bearings as shown in Figure 1. [Figure 9] Cross-sectional view showing a ball bearing according to the first embodiment of this invention. [Figure 10] Figure 9 shows the ball bearing, corresponding to Figure 2. [Figure 11] Figure 9 shows the ball bearing, corresponding to Figure 3. [Figure 12] Enlarged cross-sectional view of the vicinity of the sealing member of the ball bearing in Figure 9. [Figure 13] Cross-sectional view along line XIII-XIII in Figure 12 [Figure 14] Figure 9 is a perspective view of the retainer, seen from the side of the retainer claws. [Figure 15] Figure 9 is a perspective view of the retainer from the side of the retainer ring portion. [Figure 16] Figure 9 is a side view of the retainer, seen from the side of the retainer ring portion. [Figure 17] A side view showing a modified example of the retainer shown in Figure 16. [Figure 18] A ball bearing according to a second embodiment of this invention is shown in relation to Figure 12. [Figure 19] Cross-sectional view along line XIX-XIX in Figure 18 [Figure 20] Figure 19 shows the axial projection as viewed from the side of the seal-side sliding contact surface. [Figure 21] A ball bearing according to the third embodiment of this invention is shown in relation to Figure 1. [Figure 22] The ball bearing in Figure 21 is shown in correspondence with Figure 2. [Figure 23] Figure 21 shows a ball bearing, corresponding to Figure 3. [Figure 24] Enlarged cross-sectional view of the vicinity of the resin cage of the ball bearing shown in Figure 21. [Figure 25] Figure 23 shows a magnified view of the retainer. [Figure 26] Figure 21 is a perspective view of the retainer, seen from the side of the retainer claws. [Modes for carrying out the invention]

[0035] Figure 1 shows, reference The ball bearing 1 shown is an example of a ball bearing. This ball bearing 1 comprises an inner ring 2, an outer ring 3 coaxially mounted radially outside the inner ring 2, a plurality of balls 5 spaced apart in the circumferential direction within an annular space 4 formed between the inner ring 2 and the outer ring 3, an annular sealing member 6 that closes one of the axial end openings on both sides of the annular space 4, and a resin cage 7 (hereinafter simply referred to as "cage 7") that maintains the circumferential spacing of the plurality of balls 5.

[0036] The outer circumference of the inner ring 2 has an inner ring raceway groove 8 on which the ball 5 rolls and makes contact, a pair of inner ring groove shoulders 9 located axially outward from the inner ring raceway groove 8, and a sliding recess 10 located axially outward from the inner ring groove shoulders 9. The inner ring raceway groove 8 is an arc groove with a concave arc-shaped cross-section along the surface of the ball 5, and is formed extending circumferentially from the axial center of the outer circumference of the inner ring 2. The pair of inner ring groove shoulders 9 are embankment-like portions that extend circumferentially on both sides that axially sandwich the inner ring raceway groove 8. The sliding recess 10 is a circumferentially extending recess formed adjacent to the axially outward side of the inner ring groove shoulders 9. The inner surface of the sliding recess 10 is in sliding contact with the seal lip 11 provided at the inner diameter side end of the seal member 6. In the figure, the surface on the inner surface of the sliding recess 10 that the seal lip 11 slides against is a cylindrical surface with a constant outer diameter along the axial direction.

[0037] The inner circumference of the outer ring 3 has an outer ring raceway groove 12 on which the ball 5 rolls and makes contact, a pair of outer ring groove shoulders 13 located axially outward from the outer ring raceway groove 12, and a seal fixing groove 14 located axially outward from the outer ring groove shoulders 13. The outer ring raceway groove 12 is an arc groove with a concave arc cross-section along the surface of the ball 5, and is formed extending circumferentially from the axial center of the inner circumference of the outer ring 3. The pair of outer ring groove shoulders 13 are embankment-like portions that extend circumferentially on both sides that axially sandwich the outer ring raceway groove 12. The seal fixing groove 14 is a groove that extends circumferentially and is formed adjacent to the axially outward side of the outer ring groove shoulders 13. A fitting portion 15 provided on the outer diameter side end of the seal member 6 is fitted and fixed into the seal fixing groove 14.

[0038] Ball 5 is sandwiched radially between the outer ring raceway groove 12 and the inner ring raceway groove 8. The axial width dimension of the outer ring raceway groove 12 is greater than half the diameter of ball 5. Also, the axial width dimension of the inner ring raceway groove 8 is greater than half the diameter of ball 5. Ball 5 is a steel ball. A ceramic ball may also be used as ball 5.

[0039] As shown in Figure 4, the sealing member 6 is an annular member formed by vulcanizing and bonding a rubber material 17 (e.g., nitrile rubber, acrylic rubber, etc.) to the surface of an annular core metal 16. The sealing member 6 has a fitting portion 15 that fits into the seal fixing groove 14, an annular plate portion 18 that extends radially inward from the fitting portion 15, and a sealing lip 11 that slides against the inner surface of the sliding recess 10. The core metal 16 has an annular plate-shaped flange portion 19 and a cylindrical portion 20 that is bent axially inward along the radial outer end of the flange portion 19. The flange portion 19 is embedded in the annular plate portion 18 of the sealing member 6, and the cylindrical portion 20 is embedded in the fitting portion 15 of the sealing member 6.

[0040] As shown in Figure 1, the sealing member 6 is provided at only one of the axial end openings on both sides of the annular space 4. That is, the axial end of the annular space 4 opposite to the axial end of the annular space 4 that is sealed by the sealing member 6 (right side in the figure) (left side in the figure) is left open without a sealing member 6 to allow lubricating oil supplied from the outside to enter the annular space 4.

[0041] The retainer 7 has a retainer annular portion 21 that extends circumferentially adjacent to the passage area of ​​the balls 5, and a retainer claw portion 22 that extends axially from the retainer annular portion 21 between adjacent balls 5 in the circumferential direction. The retainer annular portion 21 and the retainer claw portion 22 are formed seamlessly as a single unit from a resin composition. The resin composition forming the retainer annular portion 21 and the retainer claw portion 22 can be made of resin material alone, but here, a resin material with added fiber reinforcement is used. The retainer 7 is preferably manufactured by injection molding.

[0042] Polyamide (PA) or super engineering plastics can be used as the base resin material for the resin composition. Examples of polyamides include polyamide 46 (PA46), polyamide 66 (PA66), and polynonameethylene terephthalamide (PA9T). Examples of super engineering plastics include polyetheretherketone (PEEK) and polyphenylene sulfide (PPS). Examples of fiber reinforcement materials added to the resin material include glass fibers, carbon fibers, and aramid fibers.

[0043] The retainer claw portion 22 is formed in a cantilever shape, with one end in the axial direction fixed to the retainer ring portion 21 and the other end in the axial direction being a free end. The axial length of the retainer claw portion 22 is set to be greater than the radius of the ball 5. The retainer claw portion 22 has a constant shape with no change in radial thickness in the axial direction.

[0044] As shown in Figures 2 and 4, an outer diameter axial groove 24 is formed on the radial outer surface 23 of the retainer claw portion 22, extending axially from the tip of the retainer claw portion 22 toward the retainer annular portion 21. Furthermore, an inner diameter axial groove 26 is formed on the radial inner surface 25 of the retainer claw portion 22, extending axially from the tip of the retainer claw portion 22 toward the retainer annular portion 21. As shown in Figure 2, the outer diameter axial groove 24 has a groove width of more than half the circumferential width of the tip of the retainer claw portion 22. Similarly, the inner diameter axial groove 26 also has a groove width of more than half the circumferential width of the tip of the retainer claw portion 22. These outer diameter axial groove 24 and inner diameter axial groove 26 give the retainer claw portion 22 an H-shape, with a cross-sectional shape perpendicular to the axial direction that opens radially outward and radially inward. Furthermore, the outer diameter axial groove 24 and the inner diameter axial groove 26 are formed open at the tip of the retainer claw portion 22 so that the shape of the retainer claw portion 22 when viewed axially from its tip side is H-shaped.

[0045] The retainer claw portion 22 has a circumferentially opposing surface 27 that faces the ball 5 in the circumferential direction. The portion of the circumferentially opposing surface 27 that receives the ball 5 in the circumferential direction is a planar shape that extends so as not to interfere with the ball 5 when the retainer claw portion 22 moves radially outward due to centrifugal force. In the figure, the circumferentially opposing surface 27 is a plane that extends parallel to an imaginary straight line connecting the center of the retainer ring portion 21 and the center of the retainer claw portion 22 when viewed in the axial direction (a plane that extends so that the circumferential width of the retainer claw portion 22 does not change along the radial direction and remains constant). The center of the retainer ring portion 21 is at the same position as the center of the inner ring 2 or the center of the outer ring 3. The center of the retainer claw portion 22 is at the midpoint of the pair of circumferentially opposing surfaces 27 located on both sides of the retainer claw portion 22 in the circumferential direction when viewed in the axial direction.

[0046] The spacing between adjacent retainer claws 22 in the circumferential direction (i.e., the spacing between circumferentially opposing surfaces 27) is preferably set to be 1.02 to 1.11 times the diameter of the ball 5 on the pitch circle of the ball 5. This reduces vibration of the retainer 7.

[0047] As shown in Figures 3 and 5, the portion of the circumferentially opposing surface 27 that receives the ball 5 in the circumferential direction is straight in the axial direction and has no circumferential inclination when viewed radially, so as not to generate an axial component force when receiving the ball 5. The retainer ring portion 21 has an axially opposing surface 28 that faces the ball 5 in the axial direction. The circumferentially opposing surface 27 and the axially opposing surface 28 are connected in a concave arc cross-section. In the figures, the curved surface connecting the circumferentially opposing surface 27 and the axially opposing surface 28 is a curved surface with a single radius (a partially cylindrical surface with a constant radius of curvature).

[0048] As shown in Figure 4, the axial end of the outer diameter axial groove 24 closest to the retainer annular portion 21 is cut upward in a concave arc shape on the outer circumference of the retainer annular portion 21. The axial end of the inner diameter axial groove 26 closest to the retainer annular portion 21 is also cut upward on the inner circumference of the retainer annular portion 21. A retainer guided surface 29 is formed on the inner circumference of the retainer annular portion 21, which slides against and is guided by the inner ring groove shoulder 9 on the outer circumference of the inner ring 2. The retainer guided surface 29 is an annular surface that slides directly against the inner ring groove shoulder 9. If the sliding gap between the retainer guided surface 29 and the inner ring groove shoulder 9 is set to a size of 0.22 mm or less, vibration of the retainer 7 can be reduced. The portion of the inner diameter axial groove 26 that cuts upward on the inner circumference of the retainer annular portion 21 opens to the retainer guided surface 29.

[0049] As shown in Figures 6 and 7, the inner diameter end of the seal lip 11 is provided with a plurality of protrusions 30 spaced apart in the circumferential direction, which slide against the sliding recess 10 on the outer circumference of the inner ring 2. The protrusions 30 are formed to extend in a direction perpendicular to the circumferential direction. As shown in Figure 7, each protrusion 30 has a convex arc-shaped cross-section.

[0050] As shown in Figure 8, the ball bearing 1 described above can be used as a bearing in an electric vehicle transmission 32 that reduces the rotation of the electric motor 31 of an electric vehicle such as an EV (battery electric vehicle) or HEV (hybrid electric vehicle). The bearing of this electric vehicle transmission 32 rotates at a wide range of rotational speeds from low to high speeds while the vehicle is running, and when the bearing rotates at the highest speed, the dmn value (pitch circle diameter of ball 5 (mm) × rotational speed (min)) -1 )) is used under the condition that it exceeds 2 million.

[0051] The transmission shown in Figure 8 includes a stator 33 of an electric motor 31, a rotor 34 of the electric motor 31, a rotating shaft 35 connected to the rotor 34, a ball bearing 1 that rotatably supports the rotating shaft 35, a second rotating shaft 36 and a third rotating shaft 37 arranged parallel to the rotating shaft 35, a first gear train 38 that transmits the rotation of the rotating shaft 35 to the second rotating shaft 36, and a second gear train 39 that transmits the rotation of the second rotating shaft 36 to the third rotating shaft 37. The stator 33 is an annular stationary member, and the rotor 34, as a rotating member, is arranged inside the stator 33. When the stator 33 is energized, the rotor 34 rotates due to the electromagnetic force acting between the stator 33 and the rotor 34, and the rotation of the rotor 34 is input to the rotating shaft 35.

[0052] As shown in Figure 5, the ball bearing 1 has an H-shaped cross-section due to the outer diameter axial groove 24 formed on the radially outer surface 23 of the cage claw portion 22 and the inner diameter axial groove 26 formed on the radially inner surface 25 of the cage claw portion 22. This allows for a reduction in the mass of the cage claw portion 22 while ensuring a high second moment of area (resistance to deformation of the cage claw portion 22 against bending moment). Therefore, even when used at high speeds, it is possible to suppress torsional deformation of the cage ring portion 21 due to the centrifugal force acting on the cage claw portion 22, and also suppress radial outward deflection deformation of the cage claw portion 22 itself. Furthermore, data analysis by the inventors has revealed that a retainer claw portion 22 having an outer diameter axial groove 24 and an inner diameter axial groove 26 can reduce the amount of deformation of the retainer claw portion 22 due to centrifugal force by at least 77% or less compared to a retainer claw portion 22 without an outer diameter axial groove 24 and an inner diameter axial groove 26.

[0053] Furthermore, as shown in Figure 2, the portion of the circumferentially opposing surface 27 of the ball bearing 1 that receives the balls 5 in the circumferential direction has a planar shape that extends parallel to the line connecting the center of the cage ring portion 21 and the center of the cage claw portion 22. Therefore, when the cage claw portion 22 moves radially outward due to the centrifugal force acting on the cage claw portion 22, it is possible to prevent the circumferentially opposing surface 27 of the cage claw portion 22 from interfering with the balls 5. In addition, since the shear resistance of the lubricating oil generated between the circumferentially opposing surface 27 of the cage claw portion 22 and the balls 5 is kept low, it is also possible to suppress heat generation in the ball bearing 1.

[0054] Furthermore, as shown in Figure 5, the circumferential opposing surface 27 and the axial opposing surface 28 of this ball bearing 1 are connected in a concave arc cross-section. This allows for a small mass at the axial tip of the cage claw portion 22 while ensuring sufficient cross-sectional area at the axial root of the cage claw portion 22. Therefore, it is possible to effectively suppress the deflection of the cage claw portion 22 due to centrifugal force acting on it.

[0055] Furthermore, as shown in Figure 4, the axial end of the outer diameter axial groove 24 on the side closest to the cage ring portion 21 is cut upward in a concave arc shape in cross-section. This allows for a small mass at the axial tip of the cage claw portion 22 while ensuring sufficient cross-sectional area at the axial root of the cage claw portion 22. Additionally, the axial end of the inner diameter axial groove 26 on the side closest to the cage ring portion 21 is also cut upward towards the inner circumference of the cage ring portion 21. This makes it possible to more effectively secure the cross-sectional area at the axial root of the cage claw portion 22. Therefore, it is possible to effectively suppress the deflection of the cage claw portion 22 due to centrifugal force acting on it.

[0056] Furthermore, as shown in Figure 4, the ball bearing 1 has a cage guided surface 29 formed on the inner circumference of the cage ring portion 21 that slides against and is guided by the outer circumference of the inner ring 2. Therefore, the cage 7 can be positioned radially by the sliding contact between the cage guided surface 29 on the inner circumference of the cage ring portion 21 and the outer circumference of the inner ring 2.

[0057] the above referenceIn the description of the embodiment, an oil-lubricated ball bearing 1 using lubricating oil as a lubricant to lubricate the inside of the bearing was used as an example, but this invention is also applicable to a grease-lubricated ball bearing 1 using grease as a lubricant to lubricate the inside of the bearing. Grease is a semi-solid lubricant that contains lubricating oil and a thickener dispersed in the lubricating oil.

[0058] Figures 9 to 16 show, The first part of this invention A ball bearing 1 according to an embodiment is shown. reference Parts corresponding to the form are denoted by the same reference numeral, and their explanations are omitted.

[0059] As shown in Figure 10, the portion of the circumferentially opposing surface 27 of the retainer claw portion 22 that receives the ball 5 in the circumferential direction is designed to have a planar shape that extends parallel to an imaginary straight line connecting the center of the retainer ring portion 21 and the center of the retainer claw portion 22 when viewed in the axial direction, so that the circumferentially opposing surface 27 does not interfere with the ball 5 when the retainer claw portion 22 moves radially outward due to centrifugal force.

[0060] As shown in Figure 11, the portion of the circumferentially opposing surface 27 that receives the ball 5 in the circumferential direction has no circumferential inclination when viewed radially and extends straight in the axial direction, so as not to generate an axial component force when receiving the ball 5.

[0061] As shown in Figure 12, the retainer claw portion 22 has a tapered shape, with its radial thickness gradually decreasing from the side closer to the retainer ring portion 21 (root side) to the side further away (tip side). The axial thickness of the retainer ring portion 21 is approximately the same as the axial distance between the ball 5 and the seal member 6 (specifically, 95% or more and less than 100% of the axial distance between the ball 5 and the seal member 6). The retainer ring portion 21 has a retainer-side sliding contact surface 40 that slides against the seal member 6 in the axial direction, and the seal member 6 has a seal-side sliding contact surface 41 that slides against the retainer-side sliding contact surface 40.

[0062] As shown in Figure 13, the retainer-side sliding surface 40 has multiple axial protrusions 42 formed at a constant pitch in the circumferential direction. Each axial protrusion 42 is formed such that its cross-sectional shape along the circumferential direction is a convex arc in the axial direction. Furthermore, the axial height of the axial protrusions 42 is set to 5% or less of the circumferential width dimension of the axial protrusion 42. In the figure, the axial height of the axial protrusions 42 is exaggerated to make their presence clearer. On the other hand, the seal-side sliding surface 41 is an annular plane perpendicular to the axial direction, and no axial protrusions 42 are formed thereon.

[0063] As shown in Figure 12, the axial projection 42 is positioned either on or radially outward from the pitch circle of the ball 5 (a virtual circle connecting the centers of multiple balls 5). Here, when the axial projection 42 is positioned on or radially outward from the pitch circle of the ball 5, it means that the virtual cylindrical surface passing through the pitch circle of the ball 5 passes through the position of the axial projection 42. When the axial projection 42 is positioned radially outward from the pitch circle of the ball 5, it means that the entire axial projection 42 is radially outward from the virtual cylindrical surface passing through the pitch circle of the ball 5. In the figure, the axial projection 42 is positioned radially outward from the pitch circle of the ball 5.

[0064] As shown in Figures 12 and 15, the axial projection 42 has a parallel apex 43, a first inclined apex 44, and a second inclined apex 45. The parallel apex 43 is the portion of the circumferential cross-section where the height of the axially convex arc-shaped apex is constant along the radial direction. The first inclined apex 44 is the portion of the circumferential cross-section where the height of the axially convex arc-shaped apex gradually decreases from the radially outer end of the parallel apex 43 toward the radially outward direction. The second inclined apex 45 is the portion of the circumferential cross-section where the height of the axially convex arc-shaped apex gradually decreases from the radially inner end of the parallel apex 43 toward the radially inward direction. As shown in Figure 12, the cross-sectional shape of the first inclined apex 44 perpendicular to the circumferential direction is an R shape that smoothly connects with the parallel apex 43. The cross-sectional shape of the second inclined apex 45 perpendicular to the circumferential direction is also an R shape that smoothly connects with the parallel apex 43.

[0065] As shown in Figure 16, the retainer guided surface 29 is an annular surface that directly slides against the inner ring groove shoulder 9. As shown in Figure 17, the retainer guided surface 29 can also be an annular surface in which a plurality of convex arc-shaped protrusions 46 projecting radially inward are formed at intervals in the circumferential direction. Setting the sliding gap between the protrusions 46 and the inner ring 2 to a size of 0.22 mm or less can reduce vibration of the retainer 7.

[0066] As shown in Figure 12, the inner diameter axial groove 26 of the radial inner surface 25 of the retainer claw portion 22 is formed to penetrate the radial inner surface 25 of the retainer claw portion 22 and the retainer guided surface 29 in the axial direction. As shown in Figure 10, the inner diameter axial groove 26 has a groove width that is more than half the circumferential width of the tip of the retainer claw portion 22.

[0067] As shown in Figure 12, the retainer annular portion 21 has a chamfered portion 47 that diagonally connects the retainer-side sliding contact surface 40 and the retainer guided surface 29 in a cross section perpendicular to the circumferential direction. Due to the provision of this chamfered portion 47, the axial width of the radial inner end of the retainer annular portion 21 is less than half the axial width of the part of the retainer annular portion 21 where the axial width is largest. In addition, the retainer annular portion 21 has a chamfered portion 48 that diagonally connects the retainer-side sliding contact surface 40 and the outer circumferential surface of the retainer annular portion 21 in a cross section perpendicular to the circumferential direction.

[0068] The outer diameter axial groove 24 on the radial outer surface 23 of the retainer claw portion 22 has a shape in which the position of the groove bottom gradually changes radially outward from the tip side of the retainer claw portion 22 toward the retainer annular portion 21. As shown in Figures 11 and 14, the outer diameter axial groove 24 has a groove width that is more than half the circumferential width of the tip of the retainer claw portion 22. In addition, an axial notch 49 is formed on the outer circumference of the retainer annular portion 21 at a position corresponding to the outer diameter axial groove 24.

[0069] As shown in Figures 11 and 14, claw tip oil passages 50 are formed on both sides in the circumferential direction of the tip of the radial outer surface 23 of the retainer claw portion 22 (the groove shoulders on both sides of the outer diameter side axial groove 24), penetrating the groove shoulders of the outer diameter side axial groove 24 in the circumferential direction. The claw tip oil passage 50 is a stepped notch that rises from the side farther from the retainer annular portion 21 to the side closer to it. By providing these claw tip oil passages 50, the lubrication performance of the ball 5 can be improved.

[0070] As shown in Figure 13, the ball bearing 1 has multiple axial projections 42 formed at a constant pitch in the circumferential direction on the cage-side sliding contact surface 40, with a cross-sectional shape that is convex in the axial direction and arc-shaped along the circumferential direction. As a result, an oil film is formed between the axial projections 42 and the seal-side sliding contact surface 41 due to the wedge film effect, and this oil film creates a fluid lubrication state between the axial projections 42 and the seal-side sliding contact surface 41, thereby keeping the contact resistance between the cage 7 and the seal member 6 extremely low. Therefore, it is possible to prevent abnormal heat generation due to sliding resistance at the contact portion between the cage 7 and the seal member 6.

[0071] Here, the lubrication state between sliding surfaces is distinguished into boundary lubrication state and fluid lubrication state. In the boundary lubrication state, several molecular layers (10) of lubricating oil adsorbed on each sliding surface are present. -5 ~10 -6 This refers to a state where the sliding surfaces are lubricated by an oil film (approximately 10 mm thick) and fine irregularities on the sliding surfaces are in direct contact. On the other hand, in a fluid lubrication state, an oil film (for example, 10 mm thick) is formed between the sliding surfaces due to the wedge film effect. -3 ~10 -1 This refers to a state where a wedge film (approximately 1 mm thick) is formed, preventing direct contact between sliding surfaces (only indirect contact occurs through the oil film). When the wedge film effect occurs and a fluid lubrication state is achieved, sliding resistance becomes almost zero, making it possible to use the device at high peripheral speeds that were previously impossible.

[0072] Furthermore, as shown in Figure 12, since the cage ring portion 21 of this ball bearing 1 is provided in sliding contact with the sealing member 6, it is possible to set a large axial thickness for the cage ring portion 21 and increase the rigidity of the cage ring portion 21. Therefore, even when used at high rotational speeds, torsional deformation of the cage ring portion 21 due to the centrifugal force acting on the cage claw portion 22 can be suppressed, and tilting of the cage claw portion 22 radially outward can be suppressed.

[0073] Furthermore, this ball bearing 1 can be installed in locations where space for bearing installation is limited and the width of the bearing must be kept small (i.e., locations where conventionally it was necessary to abandon the use of sealed ball bearings and instead use open-type ball bearings with both axial ends open without a sealing member 6).

[0074] Furthermore, as shown in Figure 11, the portion of the ball bearing 1 that receives the balls 5 on the circumferentially opposing surfaces 27 has a straight shape that extends straight in the axial direction without any circumferential inclination. Therefore, when the balls 5 are received by the cage claw portion 22, no axial force is generated in the cage claw portion 22. As a result, it is possible to prevent the cage 7 from being strongly pressed against the seal member 6 in the axial direction, and to effectively suppress the sliding resistance at the contact portion between the cage 7 and the seal member 6.

[0075] Furthermore, as shown in Figure 12, this ball bearing 1 employs an axial projection 42 having a parallel top portion 43 and a first inclined top portion 44. Therefore, when the bearing rotates at a low speed and the centrifugal force acting on the cage claw portion 22 is relatively small, an oil film can be formed between the parallel top portion 43 of the axial projection 42 and the seal-side sliding contact surface 41 due to the wedge film effect. Also, when the bearing rotates at a high speed and the centrifugal force acting on the cage claw portion 22 is relatively large, an oil film can be formed between the parallel top portion 43 and the first inclined top portion 44 of the axial projection 42 and the seal-side sliding contact surface 41 due to the wedge film effect, even when the cage annular portion 21 undergoes relatively large torsional deformation. In this way, it is possible to stably form an oil film between the cage 7 and the seal member 6 due to the wedge film effect, regardless of the rotational speed of the bearing.

[0076] Furthermore, as shown in Figure 12, the ball bearing 1 has an R-shaped cross-section perpendicular to the circumferential direction of the first inclined apex 44, and the first inclined apex 44 and the parallel apex 43 are smoothly connected. Therefore, when the cage ring portion 21 undergoes relatively large torsional deformation, it is possible to stably form an oil film between the parallel apex 43 and the first inclined apex 44 and the seal-side sliding contact surface 41 due to the wedge film effect.

[0077] Furthermore, as shown in Figure 12, the axial projection 42 of this ball bearing 1 is positioned to coincide with or radially outward of the pitch circle of the ball 5. Therefore, when torsional deformation occurs in the cage ring portion 21 due to centrifugal force acting on the cage claw portion 22, causing the cage claw portion 22 to tilt radially outward, it is possible to prevent the cage-side sliding contact surface 40 and the seal-side sliding contact surface 41 from coming into contact at a position radially outward from the axial projection 42 due to this torsional deformation.

[0078] Furthermore, as shown in Figure 12, in this ball bearing 1, the position of the groove bottom of the outer diameter side axial groove 24 gradually changes radially outward from the tip side of the cage claw portion 22 toward the cage ring portion 21. As a result, the lubricating oil supplied into the outer diameter side axial groove 24 moves from the tip side of the cage claw portion 22 toward the cage ring portion 21 by the pumping action and is introduced into the region between the cage ring portion 21 and the seal member 6. Therefore, it is possible to sufficiently lubricate the space between the seal side sliding surface 41 and the axial projection 42 and effectively form an oil film with a wedge film.

[0079] Furthermore, since the axial end of the ball bearing 1 opposite to the axial end of the annular space 4 that is sealed by the sealing member 6 is open, it is possible to sufficiently lubricate the space between the sealing side sliding contact surface 41 and the axial projection 42, thereby reliably forming an oil film with a wedge-shaped film.

[0080] Figure 18 shows, 2nd The ball bearing 1 according to the embodiment is shown. 1In the embodiment, an axial projection 42 is provided on the retainer-side sliding contact surface 40 of the retainer-side sliding contact surface 40 and the seal-side sliding contact surface 41, whereas the 2 The embodiment differs in that an axial projection 42 is provided on the seal-side sliding contact surface 41, but the other configurations are the same. 1 Parts corresponding to the embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0081] As shown in Figure 19, the seal-side sliding surface 41 has multiple axial protrusions 42 formed at a constant pitch in the circumferential direction. The axial protrusions 42 are molded into the rubber material 17 that constitutes the seal member 6 using a mold. Each axial protrusion 42 is formed such that its cross-sectional shape along the circumferential direction is a convex arc in the axial direction. Furthermore, the axial height of the axial protrusion 42 is set to 5% or less of the circumferential width dimension of the axial protrusion 42. In the figure, the axial height of the axial protrusion 42 is exaggerated to make the presence of the axial protrusion 42 easier to understand. On the other hand, the retainer-side sliding surface 40 is an annular plane perpendicular to the axial direction, and no axial protrusions 42 are formed thereon.

[0082] As shown in Figure 18, the axial projection 42 is positioned either on or radially outward from the pitch circle of the ball 5 (a virtual circle connecting the centers of multiple balls 5).

[0083] As shown in Figures 18 and 20, the axial projection 42 has a parallel apex 43, a first inclined apex 44, and a second inclined apex 45. The parallel apex 43 is the portion of the circumferential cross-section where the height of the axially convex arc-shaped apex is constant along the radial direction. The first inclined apex 44 is the portion of the circumferential cross-section where the height of the axially convex arc-shaped apex gradually decreases from the radially outer end of the parallel apex 43 toward the radially outward direction. The second inclined apex 45 is the portion of the circumferential cross-section where the height of the axially convex arc-shaped apex gradually decreases from the radially inner end of the parallel apex 43 toward the radially inward direction. As shown in Figure 18, the cross-sectional shape of the first inclined apex 44 perpendicular to the circumferential direction is an R shape that smoothly connects with the parallel apex 43. The cross-sectional shape of the second inclined apex 45 perpendicular to the circumferential direction is also an R shape that smoothly connects with the parallel apex 43.

[0084] As shown in Figure 19, the ball bearing 1 has multiple axial projections 42 formed at a constant pitch in the circumferential direction on the seal-side sliding contact surface 41, with a cross-sectional shape that is convex in the axial direction. As a result, an oil film is formed between the axial projections 42 and the cage-side sliding contact surface 40 due to the wedge film effect. This oil film creates a fluid lubrication state between the axial projections 42 and the cage-side sliding contact surface 40, which can keep the contact resistance between the cage 7 and the seal member 6 extremely low. Therefore, it is possible to prevent abnormal heat generation due to sliding resistance at the contact portion between the cage 7 and the seal member 6.

[0085] Furthermore, as shown in Figure 18, this ball bearing 1 employs an axial projection 42 having a parallel top portion 43 and a first inclined top portion 44. Therefore, when the bearing rotates at a low speed and the centrifugal force acting on the cage claw portion 22 is relatively small, an oil film can be formed between the parallel top portion 43 of the axial projection 42 and the cage-side sliding contact surface 40 due to the wedge film effect. Also, when the bearing rotates at a high speed and the centrifugal force acting on the cage claw portion 22 is relatively large, an oil film can be formed between the parallel top portion 43 and the first inclined top portion 44 of the axial projection 42 and the cage-side sliding contact surface 40, even when the cage annular portion 21 undergoes relatively large torsional deformation. In this way, it is possible to stably form an oil film between the cage 7 and the sealing member 6 due to the wedge film effect, regardless of the bearing's rotational speed.

[0086] Furthermore, as shown in Figure 18, the ball bearing 1 has an R-shaped cross-section perpendicular to the circumferential direction of the first inclined apex 44, and the first inclined apex 44 and the parallel apex 43 are smoothly connected. Therefore, when the cage ring portion 21 undergoes relatively large torsional deformation, it is possible to stably form an oil film between the parallel apex 43 and the first inclined apex 44 and the cage-side sliding contact surface 40 due to the wedge film effect.

[0087] Furthermore, as shown in Figure 18, the ball bearing 1 has an inner diameter axial groove 26 on the inner circumference of the cage 7. Therefore, lubricating oil supplied to the radially inner region of the cage claw portion 22 is introduced through the inner diameter axial groove 26 into the region between the cage annular portion 21 and the sealing member 6. As a result, it is possible to sufficiently lubricate the space between the cage side sliding surface 40 and the axial projection 42, and effectively form an oil film with a wedge-shaped film.

[0088] Other effects and benefits reference Form and the 1 This is the same as the embodiment.

[0089] Figures 21 to 26 show the first 3 The ball bearing 1 according to the embodiment is shown. 3 The embodiment is the 2 Compared to the embodiment, a sealing member 51 is added, and the shape of part of the retainer 7 is different, but the other configurations are the same. 2 Parts corresponding to the embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0090] As shown in Figure 21, a sealing member 6 is provided at one of the axial end openings of the annular space 4, and a sealing member 51 is also provided at the other end opening. A lubricant is sealed in the annular space 4 between the sealing member 6 and the sealing member 51.

[0091] As shown in Figures 22 and 23, the retainer claw portion 22 has a circumferentially opposing surface 27 that faces the ball 5 in the circumferential direction. The portion of the circumferentially opposing surface 27 that receives the ball 5 in the circumferential direction has a planar shape that extends so as not to interfere with the ball 5 when the retainer claw portion 22 moves radially outward due to centrifugal force. As shown in Figure 22, the circumferentially opposing surface 27 is a plane that, when viewed in the axial direction, is inclined in a direction that gradually approaches a virtual straight line connecting the center of the retainer ring portion 21 and the center of the retainer claw portion 22 from the radially outside to the radially inside (a plane that extends such that the circumferential width of the retainer claw portion 22 gradually decreases from the radially outside to the radially inside).

[0092] As shown in Figure 24, the retainer ring portion 21 is provided with a stepped portion 52 that rises radially outward from the radially outer surface of the base portion of the retainer claw portion 22. By providing this stepped portion 52, when the lubricant sealed in the annular space 4 moves towards the retainer ring portion 21 along the outer diameter side axial groove 24, a portion of the lubricant can be received by the stepped portion 52 and returned to the side of the ball 5.

[0093] As shown in Figure 25, the circumferential opposing surface 27 and the axial opposing surface 28 are connected by a curved surface with a composite radius. In the figure, the curved surface connecting the circumferential opposing surface 27 and the axial opposing surface 28 consists of a partially cylindrical tip-side R surface 53 connected to the circumferential opposing surface 27 and having a radius of curvature R2 smaller than the radius R1 of the ball 5, a partially cylindrical root-side R surface 54 connected to the axial opposing surface 28 and having a radius of curvature R3 larger than the radius R1 of the ball 5, and an intermediate R surface 55 that smoothly connects the tip-side R surface 53 and the root-side R surface 54.

[0094] This ball bearing 1 is the 2 It has the same effects and advantages as the embodiment.

[0095] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0096] 1 ball bearing 2 Inner ring 3 Outer ring 4. Ring space 5 balls 6. Sealing member 7. Resin retainer 21 Retainer ring portion 22 Cage claw part 23 Radial outer surface 24 Outer diameter axial groove 25 Radial inner surface 26 Inner diameter side axial groove 27 Facing surfaces in the circumferential direction 28 Axial opposing surfaces 29 Cage guided surface 31 Electric motor 32 Electric Vehicle Transmissions 40 Cage side sliding surface 41 Seal-side sliding contact surface 42 Axial projection 43 Parallel top 44 First slope top

Claims

1. Inner ring (2), An outer ring (3) is provided coaxially on the radially outer side of the inner ring (2), Multiple balls (5) are incorporated into the annular space (4) formed between the inner ring (2) and the outer ring (3), The system comprises a resin holder (7) that holds the plurality of balls (5), The resin cage (7) is a ball bearing having a cage annular portion (21) that extends circumferentially adjacent to the passage area of ​​the balls (5), and a cantilever-shaped cage claw portion (22) that extends axially between adjacent balls (5) in the circumferential direction from the cage annular portion (21), The retainer claw portion (22) has a tapered shape, with its radial thickness gradually decreasing from the side closer to the retainer ring portion (21) to the side further away. An outer diameter axial groove (24) is formed on the radial outer surface (23) of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21). An inner diameter axial groove (26) is formed on the radial inner surface (25) of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21). The retainer claw portion (22) has an H-shape in which the cross-sectional shape perpendicular to the axial direction is open radially outward and radially inward due to the outer diameter side axial groove (24) and the inner diameter side axial groove (26). The annular space (4) further includes an annular sealing member (6) that closes one end opening in the axial direction, The retainer ring portion (21) has a retainer-side sliding contact surface (40) that slides against the sealing member (6) in the axial direction, The sealing member (6) has a sealing side sliding surface (41) that slides against the retainer side sliding surface (40), On one of the sliding contact surfaces, the retainer-side sliding contact surface (40) and the seal-side sliding contact surface (41), a plurality of axial projections (42) are formed at a constant pitch in the circumferential direction, with a cross-sectional shape that is convex in the axial direction and has an arc shape along the circumferential direction. The axial projection (42) is characterized by having a parallel apex (43) in a cross section along the circumferential direction, where the height of the arc-shaped apex is convex in the axial direction is constant along the radial direction, and an inclined apex (44) in a cross section along the circumferential direction, where the height of the arc-shaped apex is convex in the axial direction gradually decreases from the radially outer end of the parallel apex (43) toward the radially outer direction.

2. The axial length of the retainer claw portion (22) is set to be greater than the radius of the ball (5), The retainer claw portion (22) has a circumferentially facing surface (27) that faces the ball (5) in the circumferential direction, The ball bearing according to claim 1, wherein the portion of the circumferentially opposing surface (27) that receives the ball (5) in the circumferential direction has a planar shape that extends so as not to interfere with the ball (5) when the retainer claw portion (22) moves radially outward due to centrifugal force.

3. The retainer ring portion (21) has an axially facing surface (28) that faces the ball (5) in the axial direction, The ball bearing according to claim 2, wherein the circumferential opposing surface (27) and the axial opposing surface (28) are connected in a concave arc shape in cross-section.

4. The ball bearing according to any one of claims 1 to 3, wherein the axial end of the outer diameter side axial groove (24) on the side closer to the cage ring portion (21) is cut up in a concave arc shape on the outer circumference of the cage ring portion (21).

5. The ball bearing according to any one of claims 1 to 4, wherein a cage guided surface (29) is formed on the inner circumference of the cage annular portion (21) and slides against and is guided by the outer circumference of the inner ring (2).

6. The ball bearing according to any one of claims 1 to 5, wherein the inclined top portion (44) has a cross-sectional shape perpendicular to the circumferential direction that is R-shaped and smoothly connects with the parallel top portion (43).

7. The ball bearing according to any one of claims 1 to 6, wherein the plurality of axial protrusions (42) are positioned to overlap with the pitch circle of the ball (5) or radially outward from there.

8. The ball bearing according to any one of claims 1 to 7, wherein the outer diameter axial groove (24) has a shape in which the position of the groove bottom gradually changes radially outward from the tip side of the retainer claw portion (22) toward the retainer annular portion (21).

9. The ball bearing according to any one of claims 1 to 8, wherein the inner diameter side axial groove (26) has a shape in which the position of the groove bottom gradually changes radially inward from the side of the tip of the retainer claw portion (22) toward the side of the retainer annular portion (21).

10. The ball bearing according to any one of claims 1 to 9, wherein the axial end of the annular space (4) opposite to the axial end closed by the sealing member (6) is left open without the sealing member (6) to allow lubricant supplied from the outside to enter the annular space (4).

11. Inner ring (2), An outer ring (3) is provided coaxially on the radially outer side of the inner ring (2), Multiple balls (5) are incorporated into the annular space (4) formed between the inner ring (2) and the outer ring (3), The system comprises a resin holder (7) that holds the plurality of balls (5), The resin cage (7) is a ball bearing having a cage annular portion (21) that extends circumferentially adjacent to the passage area of ​​the balls (5), and a cantilever-shaped cage claw portion (22) that extends axially between adjacent balls (5) in the circumferential direction from the cage annular portion (21), The retainer claw portion (22) has a tapered shape, with its radial thickness gradually decreasing from the side closer to the retainer ring portion (21) to the side further away. An outer diameter axial groove (24) is formed on the radial outer surface (23) of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21). An inner diameter axial groove (26) is formed on the radial inner surface (25) of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21). The retainer claw portion (22) has an H-shape in which the cross-sectional shape perpendicular to the axial direction is open radially outward and radially inward due to the outer diameter side axial groove (24) and the inner diameter side axial groove (26). The ball bearing is characterized in that the outer diameter axial groove (24) has a shape in which the position of the groove bottom gradually changes radially outward from the tip side of the cage claw portion (22) toward the cage annular portion (21).

12. The axial length of the retainer claw portion (22) is set to be greater than the radius of the ball (5), The retainer claw portion (22) has a circumferentially facing surface (27) that faces the ball (5) in the circumferential direction, The ball bearing according to claim 11, wherein the portion of the circumferentially opposing surface (27) that receives the ball (5) in the circumferential direction has a planar shape that extends so as not to interfere with the ball (5) when the retainer claw portion (22) moves radially outward due to centrifugal force.

13. The retainer ring portion (21) has an axially facing surface (28) that faces the ball (5) in the axial direction, The ball bearing according to claim 12, wherein the circumferential opposing surface (27) and the axial opposing surface (28) are connected in a concave arc shape in cross-section.

14. The ball bearing according to any one of claims 11 to 13, wherein the axial end of the outer diameter side axial groove (24) on the side closer to the cage ring portion (21) is cut up in a concave arc shape on the outer circumference of the cage ring portion (21).

15. The ball bearing according to any one of claims 11 to 14, wherein a cage guided surface (29) is formed on the inner circumference of the cage annular portion (21) and slides against and is guided by the outer circumference of the inner ring (2).

16. The ball bearing according to any one of claims 11 to 15, wherein the inner diameter axial groove (26) has a shape in which the position of the groove bottom gradually changes radially inward from the side of the tip of the retainer claw portion (22) toward the side of the retainer annular portion (21).

17. Inner ring (2), An outer ring (3) is provided coaxially on the radially outer side of the inner ring (2), Multiple balls (5) are incorporated into the annular space (4) formed between the inner ring (2) and the outer ring (3), The system comprises a resin holder (7) that holds the plurality of balls (5), The resin cage (7) is a ball bearing having a cage annular portion (21) that extends circumferentially adjacent to the passage area of ​​the balls (5), and a cantilever-shaped cage claw portion (22) that extends axially between adjacent balls (5) in the circumferential direction from the cage annular portion (21), The retainer claw portion (22) has a tapered shape, with its radial thickness gradually decreasing from the side closer to the retainer ring portion (21) to the side further away. An outer diameter axial groove (24) is formed on the radial outer surface (23) of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21). An inner diameter axial groove (26) is formed on the radial inner surface (25) of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21). The retainer claw portion (22) has an H-shape in which the cross-sectional shape perpendicular to the axial direction is open radially outward and radially inward due to the outer diameter side axial groove (24) and the inner diameter side axial groove (26). The ball bearing is characterized in that the inner diameter axial groove (26) has a shape in which the position of the groove bottom gradually changes radially inward from the side of the tip of the cage claw portion (22) toward the side of the cage annular portion (21).

18. The axial length of the retainer claw portion (22) is set to be greater than the radius of the ball (5), The retainer claw portion (22) has a circumferentially facing surface (27) that faces the ball (5) in the circumferential direction, The ball bearing according to claim 17, wherein the portion of the circumferentially opposing surface (27) that receives the ball (5) in the circumferential direction has a planar shape that extends so as not to interfere with the ball (5) when the retainer claw portion (22) moves radially outward due to centrifugal force.

19. The retainer ring portion (21) has an axially facing surface (28) that faces the ball (5) in the axial direction, The ball bearing according to claim 18, wherein the circumferential opposing surface (27) and the axial opposing surface (28) are connected in a concave arc shape in cross-section.

20. The ball bearing according to any one of claims 17 to 19, wherein the axial end of the outer diameter side axial groove (24) on the side closer to the cage ring portion (21) is cut up in a concave arc shape on the outer circumference of the cage ring portion (21).

21. The ball bearing according to any one of claims 17 to 20, wherein a cage guided surface (29) is formed on the inner circumference of the cage annular portion (21) and slides against and is guided by the outer circumference of the inner ring (2).

22. An electric motor (31) for an electric vehicle, using a ball bearing according to any one of claims 1 to 21.

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