Jade Axle

Abstract

The present invention provides a ball bearing that can prevent the cage claws from interfering with the balls due to deformation of the cage claws caused by centrifugal force when used at high rotational speeds. [Solution] In a ball bearing in which a resin cage 6 has a cage ring portion 9 and a plurality of pairs of cage claw portions 10, and a concave spherical pocket 11 for housing each ball 5 is formed between each pair of cage claw portions 10, the pocket 11 is formed such that the center position O2 of the pocket 11 in a stationary state is offset radially inward from the center position O1 of the ball 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. A ball bearing generally has an outer ring, an inner ring disposed radially inward of the outer ring, a plurality of balls incorporated between the outer ring and the inner ring, and a cage for holding the plurality of balls.

[0003] As such a cage, for example, resin cages (so-called crown-shaped cages) as disclosed in Patent Documents 1 and 2 are known. This resin cage has a cage annular portion and a plurality of pairs of cage claw portions in a cantilever beam shape extending axially from the cage annular portion, and a concave spherical pocket for accommodating balls is formed between each pair of cage claw portions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in recent years, in the field of electric vehicles such as EVs (battery electric vehicles) and HEVs (hybrid electric vehicles), the number of electric vehicles equipped with an e-Axle in which an electric motor for vehicle running, an inverter, and a speed reducer are integrated has been increasing. Along with the increase in the output of this e-Axle, the high-speed rotation of the electric motor for vehicle running has been promoted. And, the ball bearing that supports the rotating shaft of this electric motor and the ball bearing that supports the rotating shaft of the speed reducer that decelerates its rotation have a dmn value (the pitch circle diameter dm (mm) of the balls × the rotational speed n (min -1There is a growing demand for performance that can handle high rotational speeds of 1.5 million to 2.2 million or even higher.

[0006] In this case, when a ball bearing using a resin cage (so-called crown-shaped cage) as described in Patent Documents 1 and 2 is used as a ball bearing that rotates at high speed as described above, it has the advantages of being lighter and having lower torque compared to a ball bearing using a metal cage. On the other hand, there is a concern that the cage claws may interfere with the balls due to deformation of the cage claws caused by centrifugal force.

[0007] In other words, when a resin cage (so-called crown-shaped cage) like those in Patent Documents 1 and 2 is used in a ball bearing used for high-speed rotation, the centrifugal force acting on the cantilever-shaped cage claws causes torsional deformation in the cage ring portion, tilting the cage claws radially outward. Simultaneously, the cage claws themselves undergo radial outward deflection deformation. As a result of these deformations, the cage claws are displaced radially outward, causing the pocket portion of the cage claws to interfere with the balls. This raises concerns that this may lead to the generation of wear particles and a reduction in bearing life due to abnormal heat generation.

[0008] To address this problem, Patent Document 1 describes attaching an annular metal deformation prevention member to a resin retainer, which spans the opening side of the pocket (the side with the tip of the retainer claw) in the circumferential direction, in order to prevent the retainer claw from deforming radially outward due to centrifugal force. However, attaching an annular metal deformation prevention member increases the number of parts, which in turn increases assembly and management man-hours, resulting in higher costs.

[0009] The problem that this invention aims to solve is to provide a ball bearing that can prevent the cage claws from interfering with the balls due to deformation of the cage claws caused by centrifugal force when used at high rotational speeds. [Means for solving the problem]

[0010] To solve the above problems, this invention provides a ball bearing with the following configuration. [Configuration 1] Outer ring and, An inner ring positioned radially inward of the outer ring, A plurality of balls are incorporated between the outer ring and the inner ring, It has a resin holder that holds the plurality of balls, The resin cage has a cage ring portion and a plurality of pairs of cantilever-shaped cage claw portions extending axially from the cage ring portion, and a concave spherical pocket for housing each ball is formed between each pair of cage claw portions in a ball bearing, A ball bearing characterized in that the pocket is formed such that, in a stationary state where no centrifugal force is acting, the center position of the pocket is offset radially inward from the center position of the ball.

[0011] With this configuration, the pocket is formed such that its center position in a stationary state is offset radially inward from the center position of the ball. This prevents the pocket portion of the cage claw from interfering with the ball when the ball bearing rotates at high speed and the centrifugal force associated with that high speed causes the cage claw to deform radially outward.

[0012] [Configuration 2] The ball bearing according to configuration 1, wherein the radially inner surface of the cage claw portion has an inclination angle θi such that, in a stationary state where no centrifugal force is acting, the surface is inclined radially inward from the root side to the tip side of the cage claw portion with respect to a straight line parallel to the axial direction.

[0013] With this configuration, when the mechanism is stationary, the radially inner surface of the retainer claw is inclined radially inward. Therefore, when the retainer claw deforms radially outward due to centrifugal force during high-speed rotation, this deformation causes the radially inner surface of the retainer claw to move closer to being parallel to the axial direction. Compared to a case where the retainer claw is formed so that its radially inner surface is parallel to the axial direction when stationary, this configuration increases the strength of the inner diameter portion of the retainer claw when it is deformed radially outward due to centrifugal force, thereby ensuring durability during high-speed rotation.

[0014] [Configuration 3] The ball bearing according to configuration 2, wherein the inclination angle θi is set in the range of 0.2° ≤ θi ≤ 1.7°.

[0015] By adopting this configuration, the inclination angle θi is set to 0.2° or more, which effectively increases the strength of the inner diameter portion of the cage claws when the cage claws are deformed radially outward due to centrifugal force. Furthermore, by setting the inclination angle θi to 1.7° or less, it is possible to prevent the cage claws from interfering with the inner ring when inserting the resin cage between the outer and inner rings during bearing assembly.

[0016] [Structure 4] The ball bearing according to configuration 2 or 3, wherein the radially outer surface of the cage claw portion has an inclination angle θo such that, in a stationary state where no centrifugal force is acting, the surface is inclined radially inward from the root side to the tip side of the cage claw portion with respect to a straight line parallel to the axial direction.

[0017] By adopting this configuration, the volume of the outer diameter portion of the retainer claw is reduced compared to the case where the retainer claw is formed so that the radially outer surface of the retainer claw is parallel to the axial direction when it is stationary. This makes it possible to reduce the amount of resin required for injection molding of the retainer.

[0018] [Composition 5] The ball bearing according to configuration 4, wherein the inclination angle θo is set to satisfy the relationship θo ≤ θi.

[0019] When this configuration is adopted, the cross-sectional area perpendicular to the axial direction of the cage claw portion increases, so that the strength of the cage claw portion against the circumferential load received due to the delay and advance of the balls can be ensured.

[0020] [Configuration 6] The ball bearing according to any one of Configurations 1 to 5, wherein an offset amount of the center position of the pocket in a stationary state where centrifugal force does not act, radially inward with respect to the center position of the ball, is set to 0.5% or more and 1.6% or less of the ball diameter of the ball.

[0021] When this configuration is adopted, since the offset amount radially inward with respect to the center position of the ball at the center position of the pocket in the stationary state is set to 0.5% or more of the ball diameter of the ball, when the cage claw portion is deformed radially outward by centrifugal force, it is possible to effectively prevent the pocket portion of the cage claw portion from interfering with the ball. Further, since the offset amount radially inward with respect to the center position of the ball at the center position of the pocket in the stationary state is set to 1.6% or less of the ball diameter of the ball, it is possible to prevent the pocket portion of the cage claw portion from interfering with the ball in the stationary state.

[0022] [Configuration 7] On the inner surface of the pocket, an oil groove is formed that extends in the radial direction at an axial position corresponding to the center of the pocket and opens to the radially inner surface of the cage claw portion. The ball bearing according to any one of Configurations 1 to 6, wherein a chamfer portion for expanding the opening area of the radially inner end of the oil groove is provided at an intersection position between the inner surface of the oil groove and the radially inner surface of the cage claw portion.

[0023] When this configuration is adopted, since the opening area of the radially inner end of the oil groove is expanded by the chamfer portion, the lubricating oil flowing along the radially inner surface of the cage claw portion during bearing rotation can be captured by the chamfer portion at the radially inner end of the oil groove and introduced into the oil groove. Therefore, the surface of the ball can be effectively lubricated, which is suitable for use at high speeds.

[0024] [Configuration 8] The ball bearing according to configuration 7, wherein the circumferential width dimension of the portion of the radially inner surface of the retainer claw that is adjacent to the chamfered portion in the circumferential direction is set to be 1.0 mm or larger.

[0025] By adopting this configuration, when injection molding the resin retainer, the resin can flow smoothly to the tip of the retainer claw, making molding defects less likely.

[0026] [Composition 9] The ball bearing according to any one of configurations 1 to 8, wherein the retainer ring portion and the retainer claw portion are integrally formed from a resin composition in which reinforcing fibers are added to a matrix resin.

[0027] [Configuration 10] A ball bearing according to any one of configurations 1 to 9, used as a bearing for supporting the rotating shaft of an electric motor for driving an electric vehicle, or as a bearing for supporting the rotating shaft of a reduction gear that reduces the rotation of the electric motor. [Effects of the Invention]

[0028] In this invention, the ball bearing is formed such that the center position of the pocket when stationary is offset radially inward from the center position of the ball. Therefore, when the ball bearing rotates at high speed and the centrifugal force associated with that high speed causes the cage claw to deform radially outward, it is possible to prevent the pocket portion of the cage claw from interfering with the ball. [Brief explanation of the drawing]

[0029] [Figure 1] Cross-sectional view showing a ball bearing according to an embodiment of this invention. [Figure 2] Cross-sectional view showing the resin retainer in Figure 1. [Figure 3] Cross-sectional view along line III-III in Figure 2 [Figure 4] Perspective view of the resin retainer in Figure 2. [Figure 5] Cross-sectional view of a ball bearing at the midpoint between adjacent balls in the circumferential direction (Figure 1). [Figure 6]Figure 1 schematically illustrates an example of the use of a ball bearing incorporated into the drive system for electric vehicles. [Figure 7] Figure 1 shows a cross-sectional view illustrating the deformation of the cage claws radially outward due to the centrifugal force associated with the high-speed rotation of the ball bearing. [Modes for carrying out the invention]

[0030] Figure 1 shows a ball bearing 1 according to an embodiment of the present invention. This ball bearing 1 has an outer ring 2, an inner ring 3 arranged coaxially radially inward of the outer ring 2, a plurality of balls 5 incorporated at regular intervals in the circumferential direction in an annular bearing space 4 formed between the outer ring 2 and the inner ring 3, and a resin cage 6 (hereinafter simply referred to as "cage 6") that holds the plurality of balls 5.

[0031] The axial direction is parallel to the central axis of the outer ring 2 (the central axis of the bearing), the radial direction is perpendicular to the central axis of the outer ring 2, and the circumferential direction is along the circumference that revolves around the central axis of the outer ring 2.

[0032] An outer ring raceway groove 7 is formed on the inner circumference of the outer ring 2, into which the ball 5 rolls and makes contact. The outer ring raceway groove 7 is a groove with a circular arc cross-section that extends circumferentially along the inner circumference of the outer ring 2. The outer diameter of the outer ring 2 can be set in the range of 60 mm to 110 mm.

[0033] An inner ring raceway groove 8 is formed on the outer circumference of the inner ring 3, into which the ball 5 rolls and makes contact. The inner ring raceway groove 8 is a groove with a circular arc cross-section that extends circumferentially around the outer circumference of the inner ring 3. The inner diameter of the inner ring 3 can be set in the range of 35 mm to 80 mm.

[0034] The ball 5 is sandwiched radially between the outer ring raceway groove 7 and the inner ring raceway groove 8. The outer ring raceway groove 7 is formed symmetrically with respect to the axial center of the outer ring 2, and the inner ring raceway groove 8 is also formed symmetrically with respect to the axial center of the inner ring 3. This ball bearing 1 is a deep groove ball bearing. Steel balls can be used as balls 5.

[0035] The bearing space 4 between the outer ring 2 and the inner ring 3 is not sealed on either of its axial sides by a sealing member or the like, and is in communication with the space outside the bearing. In other words, the bearing space 4 between the outer ring 2 and the inner ring 3 is in communication with the space outside the bearing so that lubricating oil supplied from the outside of the bearing can be introduced into the bearing space 4 between the outer ring 2 and the inner ring 3 during bearing rotation, and the inside of the bearing can be lubricated with that lubricating oil.

[0036] The retainer 6 has a retainer ring portion 9 that extends circumferentially on one axial side (left side in the figure) of the ball 5, and a plurality of retainer claw portions 10 that extend from the retainer ring portion 9 through the space between adjacent balls 5 in the circumferential direction to the other axial side (right side in the figure). The retainer claw portions 10 are formed in a cantilever shape, with one end on the axial side (left side in the figure) fixed to the retainer ring portion 9 and the other end on the axial side (right side in the figure) being a free end. The retainer ring portion 9 and each retainer claw portion 10 are formed seamlessly as a single unit from a resin composition in which reinforcing fibers are added to a matrix resin.

[0037] Engineering plastics such as polyphthalamide resin (PPA), polyamide resin (PA), polyetheretherketone resin (PEEK), and polyphenylene sulfide resin (PPS) can be used as the matrix resin constituting the resin composition. For polyamide resin (PA), polyamide 46 (PA46), polyamide 66 (PA66), and polynonameethylene terephthalamide (PA9T) can be used. Reinforcing fibers such as glass fibers, carbon fibers, and aramid fibers can be added to the matrix resin. The reinforcing fibers are blended in a proportion of 10 to 50% by weight of the resin composition forming the retainer 6.

[0038] As shown in Figure 3, multiple pairs (9 pairs in the figure) of retainer claws 10 are provided, corresponding to multiple balls 5 (see Figure 1). The number of pairs of retainer claws 10 is the same as the number of balls 5 (9 in this case). Between each pair of retainer claws 10, a pocket 11 is formed to accommodate the balls 5 (see Figure 1). The inner surface of the pocket 11 (the surface of the retainer claws 10 and the retainer ring portion 9 facing the balls 5) is a concave spherical surface that conforms to the surface of the balls 5.

[0039] As shown in Figure 5, the radially inner surface 12 of the retainer claw portion 10 has an inclination angle θi that, in a stationary state without centrifugal force acting, inclins radially inward from the root side to the tip side of the retainer claw portion 10 with respect to a straight line parallel to the axial direction. Similarly, the radially outer surface 13 of the retainer claw portion 10 also has an inclination angle θo that, in a stationary state without centrifugal force acting, inclins radially inward from the root side to the tip side of the retainer claw portion 10 with respect to a straight line parallel to the axial direction. In the figure, the dashed line shows a comparative example retainer without an inclination angle, that is, a retainer in which the retainer claw portion 10 is formed such that, in a stationary state, the radially inner surface and the radially outer surface of the retainer claw portion 10 are parallel to the axial direction.

[0040] The inclination angle θi of the radially inner surface 12 of the retainer claw portion 10 is set within the range of 0.2° ≤ θi ≤ 1.7°. The inclination angle θo of the radially outer surface 13 of the retainer claw portion 10 is set to satisfy the relationship θo ≤ θi (the figure shows an example where θi = θo). The radially inner surface 12 and the radially outer surface 13 of the retainer claw portion 10 are formed in a conical shape such that the cross-section perpendicular to the circumferential direction is a straight line. In the figure, the magnitude of the inclination is exaggerated for clarity; the actual magnitude of the inclination is a fraction of or even smaller than the magnitude shown in the figure.

[0041] As shown in Figure 1, the pocket 11 is formed such that the center position of the pocket 11 (center position of the concave spherical surface) O2 in the stationary state is offset radially inward from the center position O1 of the ball 5. The amount of radial inward offset of the center position O2 of the pocket 11 relative to the center position O1 of the ball 5 in the stationary state (i.e., the difference between the radius of the imaginary circle connecting the centers of the concave spherical surface of the pocket 11 and the radius of the pitch circle connecting the centers of the ball 5) is set to be between 0.5% and 1.6% of the diameter of the ball 5.

[0042] Here, the center position O1 of ball 5 is the position of the center of ball 5 when ball 5 is positioned such that the size of the radial internal clearance between ball 5 and the outer ring raceway groove 7 and the size of the radial internal clearance between ball 5 and the inner ring raceway groove 8 are maximized. Also, the center position O2 of pocket 11 is the position of the center of the sphere if the concave spherical inner surface of pocket 11 is a perfect sphere, and if the concave spherical inner surface of pocket 11 is not a perfect sphere (for example, an ellipsoid), it is the position of the point where the average distance from the concave spherical inner surface is minimized.

[0043] Furthermore, the retainer ring portion 9 and retainer claw portion 10 shown in Figure 5 have a cross-sectional shape obtained by rotating the retainer of the comparative example shown by the dashed line radially inward by an angle of inclination θi, centered on one end of the inner circumference of the retainer ring portion 9 on the axial side (left side in the figure).

[0044] As shown in Figure 2, an oil groove 14 is formed on the inner surface of the pocket 11, extending radially at an axial position corresponding to the center of the pocket 11 (center of the concave spherical surface). The oil groove 14 is a groove with a circular arc cross-section that extends radially along the inner surface of the pocket 11 and the retainer 6. The radial outer end of the oil groove 14 is open to the radial outer surface 13 of the retainer claw portion 10, and the radial inner end of the oil groove 14 is open to the radial inner surface 12 of the retainer claw portion 10.

[0045] As shown in Figures 3 and 4, a chamfered portion 15 is provided at the intersection of the inner surface of the oil groove 14 and the radially inner surface 12 of the retainer claw portion 10. This chamfered portion 15 increases the open area at the radially inner end of the oil groove 14. Here, the chamfered portion 15 is shown as a C-shaped chamfer, where the corner where the inner surface of the oil groove 14 and the radially inner surface 12 of the retainer claw portion 10 intersect is cut off at an angle. However, it is also possible to adopt an R-shaped chamfer, where the corner where the inner surface of the oil groove 14 and the radially inner surface 12 of the retainer claw portion 10 intersect is cut off in an arc shape.

[0046] The circumferential width dimension of the chamfered portion 15 shown in Figure 3 is 0.1 mm or larger. In addition, the circumferential width dimension of the portion of the radially inner surface 12 of the retainer claw portion 10 that is adjacent to the chamfered portion 15 in the circumferential direction (i.e., the portion where the chamfered portion 15 is not formed) is set to be 1.0 mm or larger.

[0047] Figure 6 shows a drive unit (e-Axle) for electric vehicles using the ball bearing 1 described above. This drive unit is an integrated unit that combines an electric motor 20 for driving electric vehicles such as EVs (battery electric vehicles) and HEVs (hybrid electric vehicles) with a reduction gear 21 that reduces the rotation of the electric motor 20.

[0048] This drive unit includes an electric motor 20 having a rotor shaft 22, an input shaft 23 of a reduction gear 21 to which the rotation of the rotor shaft 22 is input, an output shaft 24 of the reduction gear 21, an input gear 25 fixed to the input shaft 23, an output gear 26 fixed to the output shaft 24, an intermediate gear 27 that reduces the rotation of the input gear 25 and transmits it to the output gear 26, and an intermediate shaft 28 fixed to the intermediate gear 27 so as to rotate together with the intermediate gear 27.

[0049] The rotor shaft 22 is a drive shaft that is rotationally driven by the electric motor 20. The output shaft 24 of the reduction gear 21 is connected to a wheel (not shown) of the electric vehicle. The input shaft 23, intermediate shaft 28, and output shaft 24 are arranged in parallel with a gap between them. The input gear 25, intermediate gear 27, and output gear 26 are helical gears. This drive device reduces the rotation of the electric motor 20 by sequentially transmitting it to the input gear 25, intermediate gear 27, and output gear 26, and outputs the reduced rotation to the wheel (not shown) from the output shaft 24.

[0050] The rotor shaft 22, input shaft 23, and intermediate shaft 28 are rotatably supported by the ball bearing 1 of this embodiment. On the other hand, the output shaft 24 is rotatably supported by a tapered roller bearing 29. The ball bearing 1 is lubricated by a continuous supply of lubricating oil from outside the bearing while it is rotating.

[0051] Here, the ball bearing 1 has a dmn value (pitch circle diameter of ball 5 dm (mm) × rotational speed n (min)). -1 It is used in high-speed rotation ranges where the RPM is between 1.5 million and 2.2 million, or even higher (for example, 2.3 million).

[0052] When the ball bearing 1 is used in such a high-speed rotation range, the centrifugal force acting on the cantilever-shaped cage claw portion 10 shown in Figure 4 causes torsional deformation in the cage annular portion 9 that tilts the cage claw portion 10 radially outward, and also causes radially outward bending deformation in the cage claw portion 10 itself. These deformations cause the cage claw portion 10 to be displaced radially outward. Therefore, there is a concern that the pocket portion 11 of the cage claw portion 10 may interfere with the ball 5.

[0053] To address this problem, in this embodiment, as shown in Figure 1, the ball bearing 1 is formed such that the center position O2 of the pocket 11 in the stationary state is offset radially inward from the center position O1 of the ball 5. Therefore, as shown in Figure 7, when the ball bearing 1 rotates at high speed and the cage claw portion 10 deforms radially outward due to the centrifugal force associated with the high-speed rotation, the center position O2 of the pocket 11 and the center position O1 of the ball 5 approach the ideal state in which they coincide. As a result, interference between the pocket 11 portion of the cage claw portion 10 and the ball 5 can be prevented.

[0054] Furthermore, as shown in Figure 5, when the ball bearing 1 is stationary, the radially inner surface 12 of the cage claw portion 10 is inclined radially inward. Therefore, as shown in Figure 7, when the cage claw portion 10 deforms radially outward due to centrifugal force during high-speed rotation, this deformation causes the radially inner surface 12 of the cage claw portion 10 to move closer to a direction parallel to the axial direction. Consequently, compared to the case where the cage claw portion 10 is formed so that the radially inner surface of the cage claw portion 10 is parallel to the axial direction when stationary, as shown by the dashed line in Figure 5, the strength of the inner diameter portion of the cage claw portion 10 when it is deformed radially outward due to centrifugal force can be increased, as shown in Figure 6, and durability during high-speed rotation can be ensured.

[0055] Furthermore, since the inclination angle θi shown in Figure 5 of this ball bearing 1 is set to 0.2° or more, as shown in Figure 7, it is possible to effectively increase the strength of the inner diameter side portion of the cage claw portion 10 when the cage claw portion 10 is deformed radially outward by centrifugal force. Also, since the inclination angle θi shown in Figure 5 is set to 1.7° or less, it is possible to prevent the cage claw portion 10 from interfering with the inner ring 3 when inserting the cage 6 between the outer ring 2 and the inner ring 3 during bearing assembly.

[0056] Furthermore, as shown in Figure 5, the radially outer surface 13 of the cage claw portion 10 of this ball bearing 1 is inclined radially inward from the root side to the tip side of the cage claw portion 10 with respect to a straight line parallel to the axial direction. Therefore, compared to the case where the cage claw portion 10 is formed so that the radially outer surface of the cage claw portion is parallel to the axial direction, as shown by the dashed line in Figure 5, the volume of the outer diameter portion of the cage claw portion 10 is smaller. As a result, it is possible to reduce the amount of resin required for injection molding of the cage 6.

[0057] Furthermore, since the inclination angle θo shown in Figure 5 of this ball bearing 1 is set to satisfy the relationship θo ≤ θi, the cross-sectional area of ​​the cage claw portion 10 perpendicular to the axial direction is large. Therefore, the strength of the cage claw portion 10 against the circumferential load received due to the lag-advance of the balls 5 can be ensured.

[0058] Furthermore, in this ball bearing 1, the amount of radial inward offset of the center position O2 of the pocket 11 relative to the center position O1 of the ball 5 in the stationary state shown in Figure 1 is set to 0.5% or more of the ball diameter of the ball 5. Therefore, as shown in Figure 7, when the cage claw portion 10 deforms radially outward due to centrifugal force, the portion of the cage claw portion 10 in the pocket 11 interferes with the ball 5. In addition, in the stationary state shown in Figure 1, the amount of radial inward offset of the center position O2 of the pocket 11 relative to the center position O1 of the ball 5 is set to 1.6% or less of the ball diameter of the ball 5. Therefore, when the stationary state is achieved, the portion of the cage claw portion 10 in the pocket 11 interferes with the ball 5.

[0059] Furthermore, as shown in Figure 3, this ball bearing 1 has an enlarged open area at the radial inner end of the oil groove 14 by the chamfered portion 15. This allows the lubricating oil flowing along the radial inner surface 12 of the cage claw portion 10 during bearing rotation to be captured by the chamfered portion 15 at the radial inner end of the oil groove 14 and introduced into the oil groove 14. As a result, the surface of the ball 5 can be effectively lubricated, making it suitable for use at high speeds.

[0060] Furthermore, in this ball bearing 1, the circumferential width dimension of the portion of the radially inner surface 12 of the cage claw portion 10 shown in Figure 3 that is adjacent to the chamfered portion 15 in the circumferential direction (i.e., the portion where the chamfered portion 15 is not formed) is set to be 1.0 mm or larger. Therefore, when the cage 6 is injection molded, the resin can flow smoothly to the tip of the cage claw portion 10, making molding defects less likely.

[0061] To confirm that adopting the cage 6 of the above embodiment prevents the cage claw portion 10 from interfering with the ball 5 due to centrifugal force deformation during high-speed rotation, an analysis model of the comparative example cage shown by the dashed line in Figure 5 and an analysis model of the example cage 6 with an inclination angle θi as shown by the solid line in Figure 5 were created. An analysis was then performed to determine whether the pocket 11 portion of the cage claw portion 10 interfered with the ball 5 when the ball bearing using the cage of each model was rotated in a high-speed rotation range where the dmn value was 2 million to 2.35 million.

[0062] The analysis conditions are as follows: ·Temperature: 120℃ • Retainer material (matrix resin): PPA resin • The inclination angle θi = inclination angle θo = 0.2° in the example. • The tilt angle of the comparative example is 0°

[0063] The analysis results are shown in the following table. [Table 1]

[0064] As shown in the analysis results above, in the comparative example, interference between the retainer claw portion 10 and the ball 5 occurred when the dmn value was 2.3 million (analysis result: ×), whereas in the embodiment, no interference between the retainer claw portion 10 and the ball 5 occurred even when the dmn value was 2.3 million (analysis result: ○). From this, it can be confirmed that by adopting the retainer 6 of the above embodiment, interference between the retainer claw portion 10 and the ball 5 due to centrifugal force deformation becomes less likely to occur.

[0065] 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]

[0066] 1 ball bearing 2 Outer ring 3. Inner Ring 5 balls 6. Resin retainer 9. Retainer ring section 10 Cage claw part 11 pockets 12 Radial inner surface 13 Radial outer surface 14 Oil groove 15 Chamfered section 20 Electric motors 21 Reducer θi Inclination angle θo Inclination angle Center position of O1 ball O2 pocket center position

Claims

1. Outer ring (2) and, An inner ring (3) is positioned radially inward of the outer ring (2), A plurality of balls (5) are incorporated between the outer ring (2) and the inner ring (3), It has a resin holder (6) that holds the plurality of balls (5), In a ball bearing, the resin cage (6) has a cage annular portion (9) and a plurality of pairs of cantilever-shaped cage claw portions (10) extending axially from the cage annular portion (9), and a concave spherical pocket (11) for housing each ball (5) is formed between each pair of cage claw portions (10), The central position (O) of the pocket (11) in a stationary state where no centrifugal force is acting. ２ ) is the center position (O １ A ball bearing characterized in that the pocket (11) is formed at a position offset radially inward from the position of the ).

2. The ball bearing according to claim 1, wherein the radially inner surface (12) of the retainer claw portion (10) has an inclination angle θi that, in a stationary state where no centrifugal force is acting, is inclined radially inward from the root side to the tip side of the retainer claw portion (10) with respect to a straight line parallel to the axial direction.

3. The ball bearing according to claim 2, wherein the inclination angle θi is set in the range of 0.2° ≤ θi ≤ 1.7°.

4. The ball bearing according to claim 2 or 3, wherein the radially outer surface (13) of the retainer claw portion (10) has an inclination angle θo such that, in a stationary state where no centrifugal force is acting, the retainer claw portion (10) is inclined radially inward from the root side to the tip side with respect to a straight line parallel to the axial direction.

5. The ball bearing according to claim 4, wherein the inclination angle θo is set to satisfy the relationship θo ≤ θi.

6. The central position (O) of the pocket (11) in a stationary state where no centrifugal force is acting. ２ The center position (O) of the ball (5) １ The ball bearing according to any one of claims 1 to 3, wherein the amount of radial inward offset relative to the ball (5) is set to 0.5% or more and 1.6% or less of the ball diameter of the ball (5).

7. An oil groove (14) is formed on the inner surface of the pocket (11), extending radially at an axial position corresponding to the center of the pocket (11) and opening to the radially inner surface (12) of the retainer claw portion (10). The ball bearing according to any one of claims 1 to 3, wherein a chamfered portion (15) is provided at the intersection of the inner surface of the oil groove (14) and the radially inner surface (12) of the retainer claw portion (10) to enlarge the open area of ​​the radially inner end of the oil groove (14).

8. The ball bearing according to claim 7, wherein the circumferential width dimension of the portion of the radially inner surface (12) of the retainer claw portion (10) that is adjacent to the chamfered portion (15) in the circumferential direction is set to be 1.0 mm or larger.

9. The ball bearing according to any one of claims 1 to 3, wherein the retainer ring portion (9) and the retainer claw portion (10) are integrally formed from a resin composition in which reinforcing fibers are added to a matrix resin.

10. A ball bearing according to any one of claims 1 to 3, used as a bearing for supporting the rotating shaft of an electric motor (20) for driving an electric vehicle, or as a bearing for supporting the rotating shaft of a reduction gear (21) that reduces the rotation of the electric motor (20).

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