Ball bearing

Abstract

The present invention provides a ball bearing capable of preventing interference between a retainer claw part and a ball due to deformation of the retainer claw part caused by centrifugal force when the ball bearing is used at high-speed rotation. The resin cage (6) has a cage circular ring section (9) and a plurality of pairs of cage claw sections (10), a concave spherical pocket (11) for housing each ball (5) is formed between each pair of cage claw sections (10), and 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 Technology

[0002] Ball bearings are mostly used as bearings to support rotating shafts in automobiles, industrial machinery, etc. Ball bearings typically have an outer ring, an inner ring disposed radially inside the outer ring, a plurality of balls assembled between the outer ring and the inner ring, and a retainer to hold the plurality of balls.

[0003] As such a retainer, for example, there are known resin retainers (so-called crown retainers) as in Patent Documents 1 and 2. The resin retainer has a retainer annular portion and multiple pairs of cantilever beam-shaped retainer claw portions extending axially from the retainer annular portion, with concave spherical pockets formed between each pair of retainer claw portions to accommodate balls.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-285506

[0005] Patent Document 2: Japanese Patent No. 6608151

[0006] However, in recent years, in the field of electric vehicles such as EVs (battery electric vehicles) and HEVs (hybrid electric vehicles), electric vehicles equipped with an e-Axle that integrates an electric motor, inverter, and reducer for vehicle operation are increasing. With the increasing output of this e-Axle, the high-speed rotation of the electric motor for vehicle operation is also progressing. Furthermore, the ball bearings supporting the rotating shaft of this electric motor and the ball bearings supporting the rotating shaft of the reducer that slows down its rotation are required to have a dmn value (the pitch circle diameter of the ball dm (mm) × rotational speed n (min)). －1 The performance corresponds to the high-speed rotation range of 1.5 million to 2.2 million or higher.

[0007] Here, as a high-speed rotating ball bearing as described above, when using a ball bearing with a resin retainer (so-called crown retainer) as described in Patent Documents 1 and 2, it has the advantages of being lightweight and having low torque compared to a ball bearing with a metal retainer. However, on the other hand, there is a concern that the retainer claw may deform due to centrifugal force, thereby causing interference between the retainer claw and the ball.

[0008] In other words, when a resin-made retainer (so-called crown retainer) like those in Patent Documents 1 and 2 is used in a ball bearing used for high-speed rotation, due to the centrifugal force acting on the cantilevered retainer claw, a torsional deformation occurs in the retainer annulus that causes the retainer claw to tilt radially outward, and a flexural deformation also occurs in the retainer claw itself. Due to these deformations, the retainer claw is displaced radially outward, and therefore the portion of the retainer claw with a pocket interferes with the ball. As a result, there is a concern that the bearing life may be reduced due to the generation of wear powder and abnormal heat generation.

[0009] To address this issue, Patent Document 1 describes a method to prevent the retainer claw from deforming radially outward due to centrifugal force. This involves installing a ring-shaped metal anti-deformation component circumferentially mounted on the opening side of the pocket (the front end side of the retainer claw) of the resin retainer. However, installing this ring-shaped metal anti-deformation component increases the number of components, leading to increased assembly and management time, and consequently, higher costs. Summary of the Invention

[0010] The problem to be solved by the present invention is to provide a ball bearing that can prevent interference between the retainer claw and the ball due to deformation of the retainer claw due to centrifugal force when used at high speed.

[0011] To address the aforementioned issues, the present invention provides a ball bearing with the following structure.

[0012] [Structure 1]

[0013] A ball bearing having:

[0014] Outer ring;

[0015] The inner ring is located radially inside the outer ring described above;

[0016] Multiple balls are assembled between the outer ring and the inner ring; and

[0017] A resin retainer holds the aforementioned multiple balls.

[0018] The aforementioned resin retainer has a retainer annular portion and multiple pairs of cantilever beam-shaped retainer claw portions extending axially from the retainer annular portion. A concave spherical pocket is formed between each pair of retainer claw portions to accommodate each of the aforementioned balls.

[0019] The aforementioned ball bearing is characterized in that,

[0020] The pocket is formed such that the center position of the pocket in a static state without centrifugal force is offset radially inward from the center position of the ball.

[0021] When this structure is adopted, since the pocket is formed in such a way that the center position of the pocket in the static state is offset radially inward from the center position of the ball, it is possible to prevent the pocket portion of the retainer claw from interfering with the ball when the ball bearing rotates at high speed and the retainer claw is deformed radially outward due to the centrifugal force accompanying the high-speed rotation.

[0022] [Structure 2]

[0023] According to the ball bearing described in Structure 1,

[0024] In a static state without centrifugal force, the radially inner surface of the retainer claw has an inclination angle θi relative to a straight line parallel to the axial direction, which is inclined radially inward from the root side of the retainer claw toward the front end side.

[0025] When this structure is adopted, since the radially inner surface of the retainer claw is inclined radially inward when stationary, when the retainer claw deforms radially outward due to centrifugal force during high-speed rotation, the radially inner surface of the retainer claw approaches a direction parallel to the axial direction due to this deformation. Therefore, compared to the case where the retainer claw is formed so that the radially inner surface of the retainer claw is parallel to the axial direction when stationary, the strength of the inner diameter portion of the retainer claw can be improved when it deforms radially outward due to centrifugal force, thus ensuring durability during high-speed rotation.

[0026] [Structure 3]

[0027] According to the ball bearing described in Structure 2,

[0028] The aforementioned tilt angle θi is set within the range of 0.2°≤θi≤1.7°.

[0029] When this structure is adopted, since the tilt angle θi is set to 0.2° or more, the strength of the inner diameter portion of the retainer claw can be effectively improved when the retainer claw is deformed radially outward due to centrifugal force. In addition, since the tilt angle θi is set to 1.7° or less, interference between the retainer claw and the inner ring can be prevented when the resin retainer is inserted between the outer and inner rings during bearing assembly.

[0030] [Structure 4]

[0031] According to the ball bearing described in structure 2 or 3,

[0032] In a static state without centrifugal force, the radially outer surface of the retainer claw has an inclination angle θo relative to a straight line parallel to the axial direction, which is inclined radially inward from the root side of the retainer claw toward the front end side.

[0033] When this structure is adopted, compared with the case where the retainer claw is formed in such a way that the radially outer surface of the retainer claw is parallel to the axial direction when it is at rest, the volume of the outer diameter side portion of the retainer claw is reduced, thus suppressing the amount of resin required for the injection molding of the retainer.

[0034] [Structure 5]

[0035] According to the ball bearing described in Structure 4,

[0036] The aforementioned tilt angle θo is set to satisfy the relationship θo≤θi.

[0037] When this structure is adopted, the cross-sectional area of ​​the retainer claw, which is perpendicular to the axial direction, becomes larger, thus ensuring the strength of the retainer claw against circumferential loads caused by the hysteresis and lead of the balls.

[0038] [Structure 6]

[0039] According to any one of the structures 1 to 5, the ball bearing

[0040] In a static state without centrifugal force, the offset of the center position of the aforementioned pocket relative to the center position of the aforementioned ball in a radially inward direction is set to be more than 0.5% and less than 1.6% of the ball diameter of the aforementioned ball.

[0041] When this structure is adopted, since the radial inward offset of the center position of the pocket relative to the center position of the ball in the static state is set to 0.5% or more of the ball diameter, interference between the pocket portion of the retainer claw and the ball can be effectively prevented when the retainer claw deforms radially outward due to centrifugal force. Furthermore, since the radial inward offset of the center position of the pocket relative to the center position of the ball in the static state is set to 1.6% or less of the ball diameter, interference between the pocket portion of the retainer claw and the ball can be prevented in the static state.

[0042] [Structure 7]

[0043] According to any one of the structures 1 to 6, the ball bearing

[0044] An oil groove is formed on the inner surface of the aforementioned pocket. The oil groove extends radially at an axial position corresponding to the center of the aforementioned pocket and opens on the radially inner side of the retainer claw portion.

[0045] At the intersection of the inner surface of the oil tank and the radially inner side of the retainer claw, a chamfered portion is provided to increase the open area of ​​the radially inner end of the oil tank.

[0046] When this structure is adopted, the open area of ​​the radially inner end of the oil groove is increased by the chamfer, thus the chamfer at the radially inner end of the oil groove can capture the lubricating oil flowing along the radially inner surface of the retainer claw during bearing rotation and guide it into the oil groove. Therefore, the surface of the ball can be effectively lubricated, making it suitable for use in high-speed rotation.

[0047] [Structure 8]

[0048] According to the ball bearing described in Structure 7

[0049] The circumferential width 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 1.0 mm or more.

[0050] When this structure is used, the resin can flow smoothly to the front end of the retainer claw during injection molding of the resin retainer, making it less likely to produce molding defects.

[0051] [Structure 9]

[0052] According to any one of the structures 1 to 8, the ball bearing

[0053] The aforementioned retainer annular portion and retainer claw portion are integrally formed from a resin composition in which reinforcing fibers are added to the matrix resin.

[0054] [Structure 10]

[0055] According to any one of the structures 1 to 9, the ball bearing

[0056] This ball bearing is used as a bearing for the rotating shaft of an electric motor used to drive an electric vehicle, or as a bearing for the rotating shaft of a reducer that slows down the rotation of the electric motor.

[0057] In the ball bearing of the present invention, since the retainer claw portion is formed such that the center position of the pocket when at rest is offset radially inward from the center position of the ball, it is possible to prevent the pocket portion of the retainer claw portion from interfering with the ball when the ball bearing rotates at high speed and the retainer claw portion deforms radially outward due to the centrifugal force accompanying the high-speed rotation. Attached Figure Description

[0058] Figure 1 This is a cross-sectional view showing the ball bearing according to an embodiment of the present invention.

[0059] Figure 2 It means Figure 1 A cross-sectional view of a resin retainer.

[0060] Figure 3 It is along Figure 2A cross-sectional view along line III-III.

[0061] Figure 4 yes Figure 2 A three-dimensional view of a resin retainer.

[0062] Figure 5 yes Figure 1 A cross-sectional view of a ball bearing at the midpoint between adjacent balls in the circumferential direction.

[0063] Figure 6 This is a schematic representation of the assembly of the drive unit used for driving an electric vehicle. Figure 1 The diagram shows an example of the use of ball bearings.

[0064] Figure 7 It means Figure 1 The diagram shows a cross-sectional view of the ball bearing rotating at high speed, with the retainer claw deformed radially outward due to the centrifugal force accompanying the high-speed rotation.

[0065] Explanation of reference numerals in the attached figures

[0066] 1…ball bearing; 2…outer ring; 3…inner ring; 5…ball; 6…resin retainer; 9…retainer annular portion; 10…retainer claw portion; 11…pocket; 12…radially inner surface; 13…radially outer surface; 14…oil groove; 15…chamfered portion; 20…electric motor; 21…reducer; θi…tilt angle; θo…tilt angle; O1…center position of the ball; O2…center position of the pocket. Detailed Implementation

[0067] Figure 1 This refers to a ball bearing 1 according to an embodiment of the present invention. The ball bearing 1 has: an outer ring 2; an inner ring 3, coaxially disposed radially inside the outer ring 2; a plurality of balls 5, circumferentially spaced apart and assembled in an annular bearing space 4 formed between the outer ring 2 and the inner ring 3; and a resin retainer 6 (hereinafter simply referred to as "retainer 6"), which holds the plurality of balls 5.

[0068] Axial direction refers to the direction parallel to the central axis of outer ring 2 (the central axis of the bearing), radial direction refers to the direction perpendicular to the central axis of outer ring 2, and circumferential direction refers to the direction along the circumference surrounding the central axis of outer ring 2.

[0069] An outer ring track groove 7 is formed on the inner circumference of the outer ring 2 for the rolling contact of the balls 5. The outer ring track groove 7 is a groove with an arc-shaped 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 to a range of 60 mm or more and 110 mm or less.

[0070] An inner ring track groove 8 is formed on the outer periphery of the inner ring 3 for the rolling contact of the balls 5. The inner ring track groove 8 is a groove with an arc-shaped cross-section that extends circumferentially along the outer periphery of the inner ring 3. The inner diameter of the inner ring 3 can be set to a range of 35 mm or more and 80 mm or less.

[0071] The balls 5 are radially sandwiched between the outer ring raceway 7 and the inner ring raceway 8. The outer ring raceway 7 is formed symmetrically with respect to the axial center of the outer ring 2, and the inner ring raceway 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 the balls 5.

[0072] The bearing space 4 between the outer ring 2 and the inner ring 3 is not sealed on either side by sealing components, and is connected to the space outside the bearing. That is, the bearing space 4 between the outer ring 2 and the inner ring 3 is connected to the space outside the bearing, so that lubricating oil supplied from the outside of the bearing during bearing rotation can be introduced into the bearing space 4 between the outer ring 2 and the inner ring 3, and the bearing interior can be lubricated by this lubricating oil.

[0073] The retainer 6 has a retainer annular portion 9 extending circumferentially on one side of the axial direction of the ball 5 (left side in the figure), and a plurality of retainer claw portions 10 extending from the retainer annular portion 9 through the circumferentially adjacent balls 5 toward the other side of the axial direction (right side in the figure). The retainer claw portions 10 are formed in a cantilever beam shape, with the end on one side of the axial direction (left side in the figure) serving as a fixed end fixed to the retainer annular portion 9, and the end on the other side of the axial direction (right side in the figure) serving as a free end. The retainer annular portion 9 and each retainer claw portion 10 are integrally formed seamlessly from a resin composition in which reinforcing fibers are added to the matrix resin.

[0074] 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. Polyamide resin (PA) such as polyamide 46 (PA46), polyamide 66 (PA66), and poly(terephthalamide nonadiamine) (PA9T) can be used. Reinforcing fibers added to the matrix resin can be glass fibers, carbon fibers, aramid fibers, etc. The reinforcing fibers are compounded in a proportion of 10% to 50% by weight of the resin composition forming the retainer 6.

[0075] like Figure 3 As shown, the retainer claw 10 and multiple balls 5 (see reference) Figure 1 Correspondingly, multiple pairs (9 pairs in the figure) are provided. The number of pairs of retainer claws 10 is the same as the number of balls 5 (9 in this case). A ball-receiving section 5 is formed between each pair of retainer claws 10 (see reference). Figure 1The inner surface of the pocket 11 (the surface of the retainer claw portion 10 and the retainer annular portion 9 opposite to the ball 5) is a concave spherical surface along the surface of the ball 5.

[0076] like Figure 5 As shown, in a static state without centrifugal force, the radially inner surface 12 of the retainer claw 10 has an inclination angle θi relative to a straight line parallel to the axial direction, tilting radially inward from the root side towards the front end side. Similarly, in a static state without centrifugal force, the radially outer surface 13 of the retainer claw 10 also has an inclination angle θo relative to a straight line parallel to the axial direction, tilting radially inward from the root side towards the front end side. In the figure, the double-dotted line indicates a retainer without an inclination angle, i.e., a retainer in which the radially inner and radially outer surfaces of the retainer claw 10 are formed parallel to the axial direction in a static state.

[0077] The inclination angle θi of the radially inner surface 12 of the retainer claw 10 is set within the range of 0.2° ≤ θi ≤ 1.7°. Furthermore, the inclination angle θo of the radially outer surface 13 of the retainer claw 10 is set to satisfy the relationship θo ≤ θi (an example of θi = θo is shown in the figure). The radially inner surface 12 and the radially outer surface 13 of the retainer claw 10 are formed into a conical shape with a straight section perpendicular to the circumferential direction. In the figure, the magnitude of the inclination is exaggerated for ease of understanding, but the actual magnitude of the inclination is approximately a fraction of or smaller than the magnitude shown in the figure.

[0078] like Figure 1 As shown, the pocket 11 is formed such that the center position (center position of the concave spherical surface) O2 of the pocket 11 in the static 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 in the static state relative to the center position O1 of the ball 5 (i.e., the difference between the radius of the imaginary circle connecting the center of the concave spherical surface of the pocket 11 and the radius of the pitch circle connecting the center of the ball 5) is set to be more than 0.5% and less than 1.6% of the ball diameter of the ball 5.

[0079] Here, the center position O1 of the ball 5 is the position of the ball 5 when the radial internal clearance between the ball 5 and the outer ring track groove 7 and the radial internal clearance between the ball 5 and the inner ring track groove 8 are both increased. Furthermore, the center position O2 of the pocket 11 is the position of the center of the sphere when the concave spherical inner surface of the pocket 11 is a perfect sphere, and the position of the point where the average distance from the concave spherical inner surface is minimized when the concave spherical inner surface of the pocket 11 is not a perfect sphere (e.g., an ellipse).

[0080] also, Figure 5 The retainer annular portion 9 and retainer claw portion 10 shown have a cross-sectional shape formed by rotating the retainer of the comparative example shown by the double-dotted line in a radially inward tilt angle θi with the end of the inner circumference of the retainer annular portion 9 on one side (left side in the figure) as the center.

[0081] like Figure 2 As shown, 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 (the center of the concave spherical surface). The oil groove 14 is a groove with an arc-shaped cross-section that extends radially along the inner surface of the pocket 11 and the retainer 6. The outer radial end of the oil groove 14 opens on the radially outer surface 13 of the retainer claw portion 10, and the inner radial end of the oil groove 14 opens on the radially inner surface 12 of the retainer claw portion 10.

[0082] like Figure 3 , Figure 4 As shown, a chamfer 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 10. Through this chamfer 15, the open area of ​​the radially inner end of the oil groove 14 is expanded. Here, the chamfer 15 is a C-shaped chamfer formed by cutting off the angle where the inner surface of the oil groove 14 intersects with the radially inner surface 12 of the retainer claw 10 at an angle and straight. However, it is also possible to use an R-shaped chamfer where the angle where the inner surface of the oil groove 14 intersects with the radially inner surface 12 of the retainer claw 10 is cut into an arc shape.

[0083] Figure 3 The circumferential width of the chamfered portion 15 shown is 0.1 mm or more. In addition, the circumferential width 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 1.0 mm or more.

[0084] Figure 6 This refers to a drive unit (e-Axle) for driving an electric vehicle that uses the aforementioned ball bearing 1. This drive unit is a unit that integrates an electric motor 20 for driving an electric vehicle such as an EV (battery electric vehicle) or HEV (hybrid electric vehicle) with a reducer 21 that slows down the rotation of the electric motor 20.

[0085] The drive unit includes: an electric motor 20 having a rotor shaft 22; an input shaft 23 of a reducer 21, which is input to the rotation of the rotor shaft 22; an output shaft 24 of the reducer 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 in a manner that rotates integrally with the intermediate gear 27.

[0086] Rotor shaft 22 is a drive shaft driven by the rotation of electric motor 20. The output shaft 24 of reducer 21 is connected to a wheel (not shown) of the electric vehicle. Input shaft 23, intermediate shaft 28, and output shaft 24 are arranged parallel to each other at intervals. Input gear 25, intermediate gear 27, and output gear 26 are all helical gears. This drive unit reduces the speed of rotation by sequentially transmitting the rotation of electric motor 20 to input gear 25, intermediate gear 27, and output gear 26, and then outputs the reduced rotation from output shaft 24 to the wheel (not shown).

[0087] 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 the tapered roller bearing 29. The ball bearing 1 is continuously supplied with lubricating oil from the outside of the bearing during rotation and is lubricated by the lubricating oil.

[0088] Here, the ball bearing 1 has a dmn value (the pitch circle diameter of ball 5 dm (mm) × rotational speed n (min)). －1 It is used in high-speed rotational regions of 1.5 million to 2.2 million or more (e.g., 2.3 million).

[0089] When using ball bearing 1 in such a high-speed rotating region, due to the action of Figure 4 The centrifugal force of the cantilevered retainer claw 10 shown generates torsional deformation in the retainer annular portion 9, causing the retainer claw 10 to tilt radially outward, and also generates radially outward flexural deformation in the retainer claw 10 itself. Due to these deformations, the retainer claw 10 is displaced radially outward. Therefore, there is a concern that the portion of the retainer claw 10 with the pocket 11 may interfere with the ball 5.

[0090] Regarding this issue, such as Figure 1 As shown, in this embodiment, the ball bearing 1 has the pocket 11 formed such that the center position O2 of the pocket 11 in the static state is offset radially inward from the center position O1 of the ball 5. Therefore, as Figure 7As shown, when the ball bearing 1 rotates at high speed and the retainer claw portion 10 deforms radially outward due to the centrifugal force accompanying the high-speed rotation, the ideal state is achieved where the center position O2 of the pocket 11 is aligned with the center position O1 of the ball 5. Therefore, interference between the portion of the retainer claw portion 10 with the pocket 11 and the ball 5 can be prevented.

[0091] In addition, such as Figure 5 As shown, when the ball bearing 1 is stationary, the radially inner surface 12 of the retainer claw portion 10 is inclined radially inward, therefore, as Figure 7 As shown, when the retainer claw 10 deforms radially outward due to the centrifugal force during high-speed rotation, the radially inner surface 12 of the retainer claw 10 approaches a direction parallel to the axial direction due to this deformation. Therefore, as shown... Figure 5 Compared to the case where the retainer claw 10 is formed so that the radially inner surface of the retainer claw 10 is parallel to the axial direction when in a static state, as shown by the double-dotted line, ... Figure 6 As shown, the strength of the inner diameter side portion of the retainer claw 10 can be improved when the retainer claw 10 is deformed radially outward due to centrifugal force, thus ensuring durability during high-speed rotation.

[0092] In addition, the ball bearing 1 will Figure 5 The tilt angle θi shown is set to 0.2° or higher, therefore, as Figure 7 As shown, the strength of the inner diameter portion of the retainer claw 10 can be effectively improved when the retainer claw 10 is deformed radially outward due to centrifugal force. Furthermore, due to the... Figure 5 The tilt angle θi shown is set to 1.7° or less, thus preventing interference between the retainer claw 10 and the inner ring 3 when the retainer 6 is inserted between the outer ring 2 and the inner ring 3 during bearing assembly.

[0093] In addition, such as Figure 5 As shown, the ball bearing 1 has the radially outer surface 13 of the retainer claw portion 10 inclined radially inward relative to a straight line parallel to the axial direction from the root side of the retainer claw portion 10 toward the front end side, thus... Figure 5 Compared to the case where the retainer claw 10 is formed with the radially outer surface of the retainer claw parallel to the axial direction, as shown by the double-dotted line, the volume of the outer diameter side portion of the retainer claw 10 is smaller. Therefore, the amount of resin required for injection molding of the retainer 6 can be suppressed.

[0094] In addition, the ball bearing 1 will Figure 5 The tilt angle θo shown is set to satisfy the relationship θo≤θi, thus the cross-sectional area of ​​the retainer claw 10 perpendicular to the axial direction is large. Therefore, the strength of the retainer claw 10 against circumferential loads caused by the hysteresis and advance of the balls 5 can be ensured.

[0095] In addition, the ball bearing 1 will Figure 1 The center position O2 of the pocket 11 in the static state is offset radially inward relative to the center position O1 of the ball 5 by an amount greater than 0.5% of the ball diameter of the ball 5, thus effectively preventing [the following]. Figure 7 As shown, when the retainer claw 10 deforms radially outward due to centrifugal force, a portion of the retainer claw 10 with the pocket 11 interferes with the ball 5. Furthermore, due to... Figure 1 The offset of the center position O2 of the pocket 11 in the static state relative to the center position O1 of the ball 5 in the radial direction is set to less than 1.6% of the ball diameter of the ball 5, so that interference between the portion of the pocket 11 of the retainer claw 10 and the ball 5 can be prevented in the static state.

[0096] In addition, such as Figure 3 As shown, the ball bearing 1 utilizes a chamfered portion 15 to enlarge the open area of ​​the radially inner end of the oil groove 14. Therefore, the chamfered portion 15 at the radially inner end of the oil groove 14 can capture the lubricating oil flowing along the radially inner surface 12 of the retainer claw portion 10 during bearing rotation and guide it into the oil groove 14. Thus, the surface of the balls 5 can be effectively lubricated, making it suitable for use in high-speed rotation.

[0097] In addition, the ball bearing 1 will Figure 3 The circumferential width of the portion of the radially inner surface 12 of the retainer claw 10 that is adjacent to the chamfer portion 15 in the circumferential direction (i.e., the portion where the chamfer portion 15 is not formed) is set to 1.0 mm or more. Therefore, when the retainer 6 is injection molded, the resin can flow smoothly to the front end of the retainer claw 10, and molding defects are less likely to occur.

[0098] To confirm that the retainer 6, as described in the above embodiment, can prevent interference between the retainer claw 10 and the ball 5 due to deformation caused by centrifugal force during high-speed rotation, a manufacturing process was carried out... Figure 5 The comparative example of the retainer shown by the double-dotted line and the analysis model of the retainer as shown in the figure. Figure 5 An analysis model of the retainer 6 with an inclination angle θi set as shown by the solid line was used to analyze whether the portion of the pocket 11 of the retainer claw 10 interferes with the ball 5 when the ball bearing using the retainer of the above models is rotated in a high-speed rotational region with a dmn value of 2 million to 2.35 million.

[0099] The analysis conditions are as follows.

[0100] Temperature: 120℃

[0101] • Retainer material (matrix resin): PPA resin

[0102] • In the embodiment, the tilt angle θi = tilt angle θo = 0.2°

[0103] • The tilt angle of the comparative example is 0°

[0104] The analysis results are shown in the table below.

[0105] Table 1

[0106] dmn value Comparative example Example 2 million 〇 〇 2.2 million 〇 〇 2.3 million × 〇 2.35 million × ×

[0107] As shown in the analysis results above, in the comparative example, interference occurred between the retainer claw 10 and the ball 5 when the dmn value was 2.3 million (analysis result: ×). In contrast, in the embodiment, even when the dmn value was 2.3 million, no interference occurred between the retainer claw 10 and the ball 5 (analysis result: ○). Therefore, it can be confirmed that by adopting the retainer 6 of the above embodiment, interference between the retainer claw 10 and the ball 5 due to centrifugal force deformation is less likely to occur.

[0108] The embodiments disclosed herein should be understood as illustrative rather than restrictive in all respects. The scope of the invention is set forth in the claims rather than in the foregoing description and is intended to include all modifications equivalent to and within the scope of the claims.

Claims

1. A ball bearing having: an outer ring (2); an inner ring (3) disposed on a radially inner side of the outer ring (2); a plurality of balls (5) assembled between the outer ring (2) and the inner ring (3); and a retainer (6) made of resin that retains the plurality of balls (5), the retainer (6) having a retainer annular portion (9) and a plurality of pairs of retainer claw portions (10) in the shape of cantilever beams extending in the axial direction from the retainer annular portion (9), a concave spherical pocket (11) that accommodates each ball (5) being formed between each pair of the retainer claw portions (10), the ball bearing being characterized in that the center position (02) of the pocket (11) in a stationary state in which no centrifugal force acts is formed so as to be a position that is offset toward the radially inner side than the center position (01) of the ball (5).

2. The ball bearing according to claim 1, characterized in that, in the stationary state in which no centrifugal force acts, a face (12) on the radially inner side of the retainer claw portion (10) has an inclination angle θι that inclines toward the radially inner side from the root side toward the tip side of the retainer claw portion (10) with respect to a straight line that is parallel to the axial direction.

3. The ball bearing according to claim 2, characterized in that the inclination angle θι is set within a range of 0.2° ≤ θι ≤ 1.7°.

4. The ball bearing according to claim 2 or 3, characterized in that, in the stationary state in which no centrifugal force acts, a face (13) on the radially outer side of the retainer claw portion (10) has an inclination angle θ0 that inclines toward the radially inner side from the root side toward the tip side of the retainer claw portion (10) with respect to a straight line that is parallel to the axial direction.

5. The ball bearing according to claim 4, characterized in that the inclination angle θ0 is set so as to satisfy a relationship of θ0 ≤ θι.

6. The ball bearing according to any one of claims 1 to 5, characterized in that the offset amount toward the radially inner side of the center position (02) of the pocket (11) in the stationary state in which no centrifugal force acts with respect to the center position (01) of the ball (5) is set to be 0.5% or more and 1.6% or less of the ball diameter of the ball (5).

7. The ball bearing according to any one of claims 1 to 6, characterized in that an oil groove (14) that extends in the radial direction at an axial position corresponding to the center of the pocket (11) and that is open at the face (12) on the radially inner side of the retainer claw portion (10) is formed in an inner surface of the pocket (11), and a chamfer portion (15) that enlarges the open area of the radially inner end of the oil groove (14) is provided at the intersection position of the inner surface of the oil groove (14) and the face (12) on the radially inner side of the retainer claw portion (10).

8. The ball bearing according to claim 7, characterized in that the width dimension in the circumferential direction of the portion of the face (12) on the radially inner side of the retainer claw portion (10) that is adjacent to the chamfer portion (15) in the circumferential direction is set to be a size of 1.0 mm or more. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 9. The ball bearing according to any one of claims 1 to 8, characterized in that the retainer annular portion (9) and the retainer claw portion (10) are integrally formed of a resin composition to which a reinforcing fiber is added in a base resin.

10. The ball bearing according to any one of claims 1 to 9, characterized in that the ball bearing is used as a bearing that supports a rotating shaft of an electric motor (20) for running of an electric automobile or a bearing that supports a rotating shaft of a speed reducer (21) that reduces the rotation of the electric motor (20).

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