Jade bearing

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: A ball bearing includes a resin cage 7 having a cage annular part 21, and a cantilevered cage claw part 22 extending from the cage annular part 21 to between circumferentially neighboring balls 5 in the axial direction. On the radial outside face of the cage annular part 21, a root side guided surface 23 is formed to slide-contact one outer ring groove shoulder part 13 out of a pair of outer ring groove shoulder parts 13. On the radial outside face at the axial end on the front end side of the cage claw part 22, a front end side guided surface 24 is formed to slide-contact the other outer ring groove shoulder part 13 out of the pair of outer ring groove shoulder parts 13. The root side guided surface 23 and the front end side guided surface 24 are formed circular so that the sectional shapes along the circumferential direction are protruded radially outward.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a ball bearing. [Background technology]

[0002] Ball bearings are often used as bearings to support rotating shafts in automobiles, industrial machines, etc. Generally, a ball bearing has an inner ring, an outer ring disposed coaxially and radially outward of the inner ring, a number of balls disposed in the annular space between the inner ring and the outer ring, and a cage that holds the number of balls.

[0003] A known example of a cage is a plastic cage (a so-called crown cage) having a cage annular portion extending circumferentially adjacent to the area through which the balls pass, and a cantilever-shaped cage claw portion extending axially from the cage annular portion between adjacent balls in the circumferential direction, as shown in Patent Document 1. 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 that follows the surface of the ball so as to embrace the ball. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3035766 Summary of the Invention [Problem 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), efforts are being made to make electric motors faster in order to reduce their size and weight. The ball bearings that support the rotating shaft to which the rotation of such electric motors is input have a dmn value (ball pitch circle diameter dm (mm) × rotation speed n (min -1 )) may be used in more than 2 million conditions.

[0006] The inventors of the present application have considered using a crown cage in a ball bearing that supports a rotating shaft that rotates at high speeds in an EV, HEV, or the like.

[0007] However, it has been found that when a crown-shaped cage is used in a ball bearing that rotates at high speed, centrifugal force acting on the cantilever-shaped cage claws causes torsional deformation in the cage annular portion in a direction that tilts the cage claws radially outward, and also causes the cage claws themselves to bend radially outward, which can cause the cage claws to interfere with the balls. If the cage claws interfere with the balls, this can cause heat generation in the ball bearing.

[0008] The problem to be solved by this invention is to provide a ball bearing in which the resin cage is less likely to deform due to centrifugal force when used at high speed rotation. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention employs the following configuration for a ball bearing. With the inner circle, an outer ring provided coaxially on the radially outer side of the inner ring; A plurality of balls are mounted in an annular space formed between the inner ring and the outer ring; a resin cage that holds the plurality of balls; an inner periphery of the outer ring is provided with an outer ring raceway groove with which the balls roll and contact, and a pair of outer ring groove shoulders located on both axial sides of the outer ring raceway groove; The resin cage has a cage annular portion extending in a circumferential direction adjacent to an area through which the balls pass, and a cantilever-shaped cage claw portion extending in an axial direction from the cage annular portion between the balls adjacent in the circumferential direction, an axial length of the cage claw portion is set to be greater than an axial width of the outer ring raceway groove, a base-side guided surface that is in sliding contact with one of the pair of outer ring groove shoulders is formed on a radially outer surface of the retainer annular portion, a tip-side guided surface that comes into sliding contact with the other of the pair of outer ring groove shoulders is formed on a radially outer surface of an axial end portion on a tip side of the cage claw portion, A ball bearing characterized in that the base side guided surface and the tip side guided surface have a cross-sectional shape along the circumferential direction formed into an arc shape that protrudes radially outward.

[0010] In this way, the root side guided surface is formed in a circular arc shape with a cross section along the circumferential direction protruding outward in the radial direction, so that an oil film is formed between the root side guided surface and one of the outer ring groove shoulders due to the wedge film effect, and the oil film creates a fluid lubrication state between the root side guided surface and the outer ring groove shoulder, making it possible to keep the contact resistance between the cage and the outer ring extremely small. Similarly, the tip side guided surface is formed in a circular arc shape with a cross section along the circumferential direction protruding outward in the radial direction, so that an oil film is formed between the tip side guided surface and the other outer ring groove shoulder due to the wedge film effect, and the oil film creates a fluid lubrication state between the tip side guided surface and the outer ring groove shoulder, making it possible to keep the contact resistance between the cage and the outer ring 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 outer ring. In addition, one of the pair of outer ring groove shoulders supports the cage ring portion from the radial outside, and the other supports the axial end portion of the tip side of the cage claw portion from the radial outside, so that the cage claw portion is less likely to bend radially outward. Therefore, even when used at high speed rotation, torsional deformation of the cage ring portion due to centrifugal force applied to the cage claw portion can be suppressed, and bending deformation of the cage claw portion itself in the radial outward direction can be suppressed.

[0011] the cage claw portion has a circumferentially opposed surface that faces the ball in the circumferential direction, It is preferable that the portion of the circumferential opposing surface that receives the balls circumferentially be configured in a planar shape extending parallel to a straight line connecting the center of the retainer annular portion and the center of the retainer claw portion so that the circumferential opposing surface does not interfere with the balls when the retainer claw portion moves radially outward due to centrifugal force.

[0012] In this way, because the circumferentially opposed surfaces of the retainer claw portions have a flat shape, it is possible to prevent the circumferentially opposed surfaces of the retainer claw portions from interfering with the balls when the retainer claw portions move radially outward due to centrifugal force acting on the retainer claw portions. In addition, the shear resistance of the lubricant generated between the circumferentially opposed surfaces of the retainer claw portions and the balls is kept low, which makes it possible to suppress heat generation in the ball bearing.

[0013] It is preferable that an axial end edge of the base side guided surface remote from the retainer claw portion and an axial end edge of the tip side guided surface remote from the retainer annular portion are rounded.

[0014] In this way, an oil film can be effectively formed between the root side guided surface and one of the outer ring groove shoulders by the wedge film effect, and an oil film can also be effectively formed between the tip side guided surface and the other outer ring groove shoulder by the wedge film effect.

[0015] It is preferable to form an escape recess extending in the circumferential direction with an axial width wider than the axial width of the outer ring raceway groove between the root side guided surface and the tip side guided surface on the radial outer surface of the retainer claw portion.

[0016] This prevents the boundary between the outer ring groove shoulder and the outer ring raceway groove from sliding against the radially outer surface of the cage annular portion or the radially outer surface of the cage claw portion, thereby making it possible to prevent localized wear of the radially outer surface of the cage annular portion or the radially outer surface of the cage claw portion at a position corresponding to the boundary between the outer ring groove shoulder and the outer ring raceway groove.

[0017] It is preferable that an oil reservoir groove is formed on a radially inner surface of each of the retainer claw portions, the oil reservoir groove extending in the axial direction from the tip of each of the retainer claw portions toward the retainer annular portion.

[0018] In this way, the lubricant that is scattered toward the outer diameter side by centrifugal force can be collected in the oil collecting groove, and the lubricant can be supplied to the inner ring.

[0019] The annular space has an opening at one end in the axial direction, and the annular space has an annular seal member. the retainer annular portion has a retainer-side sliding surface that is in sliding contact with the seal member while facing the retainer in the axial direction, the seal member has a seal-side sliding surface that is in sliding contact with the cage-side sliding surface, It is preferable to adopt a configuration in which a plurality of axial protrusions, each of which has an axially convex arc-shaped cross-sectional shape along the circumferential direction, is formed at a constant pitch in the circumferential direction on one of the retainer side sliding surface and the seal side sliding surface.

[0020] In this way, a plurality of axial protrusions, each having a circumferentially convex arc-shaped cross section, are formed at a constant pitch in the circumferential direction on one of the retainer-side sliding surface and the seal-side sliding surface, so that an oil film is formed between the axial protrusions and the sliding surface by the wedge film effect, and the oil film creates a fluid lubrication state between the axial protrusions and the sliding surface, so that the contact resistance between the retainer and the seal member can be kept extremely small. Therefore, it is possible to prevent abnormal heat generation due to the sliding resistance of the contact portion between the retainer and the seal member. In addition, since the retainer annular portion is provided in sliding contact with the seal member, the axial thickness of the retainer annular portion can be set large, and the rigidity of the retainer annular portion can be increased. Therefore, even when used at high speed rotation, it is possible to suppress torsional deformation of the retainer annular portion due to the centrifugal force applied to the retainer claw portion.

[0021] It is preferable that the axial protrusion be configured to have a parallel apex portion in which the height of the axially convex arc-shaped apex in a cross section taken along the circumferential direction is constant along the radial direction, and a sloped apex portion in which the height of the axially convex arc-shaped apex in a cross section taken along the circumferential direction gradually decreases from the radial outer end of the parallel apex toward the radial outward direction.

[0022] In this way, when the bearing rotates at a low speed and the centrifugal force applied to the cage claws is relatively small, an oil film can be formed between the parallel tops of the axial protrusions and the sliding contact surface due to the wedge film effect. Also, when the bearing rotates at a high speed and the centrifugal force applied to the cage claws is relatively large, an oil film can be formed between the parallel tops and inclined tops of the axial protrusions and the sliding contact surface due to the wedge film effect in a state in which the cage annular portion is subjected to a relatively large torsional deformation. In this way, an oil film can be stably formed between the cage and the seal member due to the wedge film effect, regardless of the rotational speed of the bearing.

[0023] It is preferable that the inclined apex portion has a cross-sectional shape perpendicular to the circumferential direction that is an R-shape that smoothly connects to the parallel apex portion.

[0024] In this way, the inclined top and the parallel top are smoothly connected, so that when an oil film is formed between the parallel top and the inclined top and the sliding surface due to the wedge film effect when the retainer annular portion is subjected to relatively large torsional deformation, the oil film can be formed stably.

[0025] The plurality of axial projections are preferably arranged at a position overlapping with the pitch circle of the ball or radially outwardly of the pitch circle.

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

[0027] It is preferable to adopt a configuration in which the axial end opposite the axial end of the annular space blocked by the sealing member is open without a sealing member so as to receive lubricant supplied from the outside into the annular space.

[0028] In this way, the base side guided surface and the tip side guided surface can be sufficiently lubricated, and an oil film can be reliably formed by a wedge film.

[0029] It is particularly suitable for use as a bearing in an electric vehicle transmission that reduces the rotation of an electric motor in an electric vehicle. Effect of the Invention

[0030] In the ball bearing of the present invention, the root guided surface is formed in a circular arc shape that protrudes radially outward in cross section along the circumferential direction, so that an oil film is formed between the root guided surface and one of the outer ring groove shoulders due to the wedge film effect, and the oil film creates a fluid lubrication state between the root guided surface and the outer ring groove shoulder, making it possible to keep the contact resistance between the cage and the outer ring extremely small. Similarly, the tip guided surface is formed in a circular arc shape that protrudes radially outward in cross section along the circumferential direction, so that an oil film is formed between the tip guided surface and the other outer ring groove shoulder due to the wedge film effect, and the oil film creates a fluid lubrication state between the tip guided surface and the outer ring groove shoulder, making it possible to keep the contact resistance between the cage and the outer ring 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 outer ring. In addition, one of the pair of outer ring groove shoulders supports the cage ring portion from the radial outside, and the other supports the axial end portion of the tip side of the cage claw portion from the radial outside, so that the cage claw portion is less likely to bend radially outward. Therefore, even when used at high speed rotation, torsional deformation of the cage ring portion due to centrifugal force applied to the cage claw portion can be suppressed, and bending deformation of the cage claw portion itself in the radial outward direction can be suppressed. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a cross-sectional view showing a ball bearing according to a first embodiment of the present invention. [Diagram 2] Cross-sectional view taken along line II-II in Figure 1. [Diagram 3] Cross-sectional view taken along line III-III in Figure 1. [Figure 4] An enlarged cross-sectional view of the vicinity of the retainer ring of the ball bearing in FIG. 1. [Diagram 5] Cross-sectional view taken along line VV in Figure 4. [Figure 6] FIG. 2 is a perspective view of the cage in FIG. 1 as seen from the cage claw portion side. [Figure 7] FIG. 2 is an enlarged view of the vicinity of the seal lip of the seal member of FIG. 1; [Figure 8] 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] Schematic diagram of an electric vehicle transmission incorporating the ball bearing shown in Figure 1. [Figure 10] FIG. 1 is a cross-sectional view showing a ball bearing according to a second embodiment of the present invention. [Figure 11] Cross-sectional view taken along line XI-XI in Figure 10. [Figure 12] A cross-sectional view taken along line XII-XII in Figure 10. [Figure 13] FIG. 11 is a perspective view of the cage of FIG. 10 as viewed from the cage claw portion side. [Figure 14] FIG. 11 is a cross-sectional view showing a ball bearing according to a third embodiment of the present invention. [Figure 15] Cross-sectional view taken along line XV-XV in Figure 14. [Figure 16] A cross-sectional view taken along line XVI-XVI in Figure 14. [Figure 17] FIG. 15 is a perspective view of the cage of FIG. 14 as seen from the cage claw portion side. [Figure 18] FIG. 13 is an enlarged cross-sectional view of the vicinity of a retainer annular portion of a ball bearing according to a fourth embodiment of the present invention; [Figure 19] A cross-sectional view taken along line XIX-XIX in FIG. 18. [Figure 20] FIG. 13 is an enlarged cross-sectional view of the vicinity of a retainer annular portion of a ball bearing according to a fifth embodiment of the present invention; [Figure 21] A cross-sectional view taken along line XXI-XXI in Figure 20. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] 1 shows a ball bearing 1 according to a first embodiment of the present invention. This ball bearing 1 has an inner ring 2, an outer ring 3 provided coaxially on the radial outside of the inner ring 2, a plurality of balls 5 assembled at intervals in the circumferential direction in annular space 4 formed between the inner ring 2 and the outer ring 3, an annular seal member 6 that closes one of the end openings on both axial sides of the annular space 4, and a resin retainer 7 (hereinafter simply referred to as "retainer 7") that maintains the circumferential spacing of the plurality of balls 5.

[0033] The inner ring 2 has an inner ring raceway groove 8 with which the balls 5 roll and make contact, a pair of inner ring groove shoulders 9 located axially outward of the inner ring raceway groove 8, and a sliding recess 10 located axially outward of 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 balls 5, and is formed extending circumferentially through the axial center of the outer circumference of the inner ring 2. The pair of inner ring groove shoulders 9 are bank-shaped parts extending circumferentially on both sides of the inner ring raceway groove 8 in the axial direction. The sliding recess 10 is a recess extending circumferentially formed adjacent to the axial outside of the inner ring groove shoulders 9. A seal lip 11 provided at the inner diameter end of the seal member 6 is in sliding contact with the inner surface of the sliding recess 10. In the figure, the surface of the inner surface of the sliding recess 10 with which the seal lip 11 is in sliding contact is a cylindrical surface having a constant outer diameter along the axial direction.

[0034] The inner circumference of the outer ring 3 is formed with an outer ring raceway groove 12 with which the balls 5 roll and make contact, a pair of outer ring groove shoulders 13 located axially outward of the outer ring raceway groove 12, and a seal fixing groove 14 located axially outward of the outer ring groove shoulders 13. The outer ring raceway groove 12 is an arc groove with a concave arc-shaped cross section along the surface of the balls 5, and is formed extending circumferentially through the axial center of the inner circumference of the outer ring 3. The pair of outer ring groove shoulders 13 are bank-shaped parts extending circumferentially on both sides of the outer ring raceway groove 12 in the axial direction. The seal fixing groove 14 is a groove extending circumferentially formed adjacent to the axial outside of the outer ring groove shoulders 13. An engagement portion 15 provided on the outer diameter side end of the seal member 6 is engaged and fixed in the seal fixing groove 14.

[0035] Balls 5 are radially sandwiched between outer ring raceway groove 12 and inner ring raceway groove 8. The axial width dimension of outer ring raceway groove 12 is greater than half the diameter of ball 5. Also, the axial width dimension of inner ring raceway groove 8 is greater than half the diameter of ball 5.

[0036] As shown in Fig. 4, the seal member 6 is an annular member formed by vulcanizing and bonding a rubber material 17 (such as nitrile rubber or acrylic rubber) to the surface of an annular core metal 16. The seal 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 seal 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 seal member 6, and the cylindrical portion 20 is embedded in the fitting portion 15 of the seal member 6.

[0037] 1, the seal member 6 is provided at only one of the end openings on both axial sides of the annular space 4. That is, the axial end on the side of the annular space 4 that is blocked by the seal member 6 (the right side in the figure) is open without the seal member 6 so that lubricating oil supplied from the outside can be received into the annular space 4.

[0038] The cage 7 has a cage annular portion 21 extending circumferentially adjacent to the area through which the balls 5 pass, and cage claw portions 22 extending axially from the cage annular portion 21 between the circumferentially adjacent balls 5. The cage annular portion 21 and the cage claw portions 22 are formed seamlessly as a single piece from a resin composition. The resin composition forming the cage annular portion 21 and the cage claw portions 22 can be made of only a resin material, but here a resin material with a fiber reinforcing material added is used.

[0039] As the resin material that is the base of the resin composition, polyamide (PA) or super engineering plastics can be used. As the polyamide, polyamide 46 (PA46), polyamide 66 (PA66), polynonamethylene terephthalamide (PA9T), etc. can be used. As the super engineering plastic, polyether ether ketone (PEEK) and polyphenylene sulfide (PPS) can be used. As the fiber reinforcing material added to the resin material, glass fiber, carbon fiber, aramid fiber, etc. can be used.

[0040] The cage claw portion 22 is formed in a cantilever shape with one axial end being a fixed end fixed to the cage annular portion 21 and the other axial end being a free end. The axial length of the cage claw portion 22 is set to be greater than the axial width of the outer ring raceway groove 12. The cage claw portion 22 has a constant shape with no change in radial thickness in the axial direction.

[0041] 1 and 6, a root-side guided surface 23 that comes into sliding contact with one of the pair of outer ring groove shoulders 13 is formed on the radially outer surface of the cage annular portion 21 at a position corresponding to the root of the cage claw portion 22. In addition, a tip-side guided surface 24 that comes into sliding contact with the other of the pair of outer ring groove shoulders 13 is formed on the radially outer surface of the axial end portion on the tip side of the cage claw portion 22.

[0042] As shown in FIG. 5, the root side guided surface 23 has a cross-sectional shape along the circumferential direction formed in an arc shape that protrudes radially outward. Here, "protruding radially outward" means that the shape protrudes radially outward with respect to a circle concentric with the cage annular portion 21. The tip side guided surface 24 (see FIG. 6) also has a cross-sectional shape along the circumferential direction formed in an arc shape that protrudes radially outward. The cross section along the circumferential direction of the root side guided surface 23 and the cross section along the circumferential direction of the tip side guided surface 24 have the same shape. The radii of curvature of the cross sections along the circumferential direction of the root side guided surface 23 and the tip side guided surface 24 can be set to be smaller than 1 / 2 the radius of the inner diameter of the outer ring groove shoulder portion 13 and larger than 1 / 10 the radius of the inner diameter of the outer ring groove shoulder portion 13.

[0043] As shown in Figure 6, in this embodiment, the root side guided surface 23 and the tip side guided surface 24 are a series of surfaces that are straight and continuous in the axial direction so that no recess is created between the root side guided surface 23 and the tip side guided surface 24.

[0044] As shown in Fig. 3, an axial end edge 25 of the base side guided surface 23 on the side remote from the retainer claw portion 22 is R-chamfered. Here, R-chamfering refers to providing a corner shape such that the cross section perpendicular to the circumferential direction is a convex arc shape, as shown in Fig. 4. As shown in Fig. 3, an axial end edge 26 of the tip side guided surface 24 on the side remote from the retainer annular portion 21 is also R-chamfered.

[0045] As shown in Fig. 2, the cage claw portion 22 has a circumferentially opposed surface 27 that faces the balls 5 in the circumferential direction. The portion of the circumferentially opposed surface 27 that receives the balls 5 in the circumferential direction has a planar shape that extends parallel to an imaginary line connecting the center of the cage annular portion 21 and the center of the cage claw portion 22 when viewed in the axial direction so that the circumferentially opposed surface 27 does not interfere with the balls 5 when the cage claw portion 22 moves radially outward due to centrifugal force. Here, the center of the cage annular portion 21 is at the same position as the center of the inner ring 2 or the center of the outer ring 3. Also, the center of the cage claw portion 22 is at the midpoint between a pair of circumferentially opposed surfaces 27 located on both circumferential sides of the cage claw portion 22 when viewed in the axial direction.

[0046] 3, the portion of circumferential opposing surface 27 that receives balls 5 in the circumferential direction extends straight in the axial direction without any circumferential inclination when viewed in the radial direction so as to generate no axial component force when receiving balls 5. Cage annular portion 21 has axial opposing surface 28 that faces balls 5 in the axial direction. Circumferential opposing surface 27 and axial opposing surface 28 are connected in a concave arc shape in cross section.

[0047] 7 and 8, a plurality of protrusions 29 that come into sliding contact with the sliding recess 10 on the outer periphery of the inner ring 2 are provided at intervals in the circumferential direction on the inner diameter side end of the seal lip 11. The protrusions 29 are formed so as to extend in a direction perpendicular to the circumferential direction. As shown in Fig. 8, each protrusion 29 has a convex arc-shaped cross section.

[0048] As shown in Fig. 9, the above-mentioned ball bearing 1 can be used as a bearing for an electric vehicle transmission 30 that reduces the rotation of an 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 30 rotates at a wide range of rotation 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 balls 5 (mm) x rotation speed (min -1 )) is used in more than 2 million conditions.

[0049] The transmission shown in FIG. 9 includes a stator 32 of an electric motor 31, a rotor 33 of the electric motor 31, a rotating shaft 34 connected to the rotor 33, a ball bearing 1 that rotatably supports the rotating shaft 34, a second rotating shaft 35 and a third rotating shaft 36 arranged parallel to the rotating shaft 34, a first gear train 37 that transmits the rotation of the rotating shaft 34 to the second rotating shaft 35, and a second gear train 38 that transmits the rotation of the second rotating shaft 35 to the third rotating shaft 36. The stator 32 is an annular stationary member, and the rotor 33 as a rotating member is arranged inside the stator 32. When the stator 32 is energized, the rotor 33 rotates due to an electromagnetic force acting between the stator 32 and the rotor 33, and the rotation of the rotor 33 is input to the rotating shaft 34.

[0050] As shown in FIG. 5, in this ball bearing 1, the root side guided surface 23 is formed in a circular arc shape in cross section along the circumferential direction that protrudes radially outward, so that an oil film is formed between the root side guided surface 23 and one of the outer ring groove shoulders 13 due to the wedge film effect, and the oil film creates a fluid lubrication state between the root side guided surface 23 and the outer ring groove shoulder 13, so that the contact resistance between the cage 7 and the outer ring 3 can be kept extremely small. Similarly, the tip side guided surface 24 shown in FIG. 1 is also formed in a circular arc shape in cross section along the circumferential direction that protrudes radially outward, so that an oil film is formed between the tip side guided surface 24 and the other outer ring groove shoulder 13 (the left outer ring groove shoulder 13) due to the wedge film effect, and the oil film creates a fluid lubrication state between the tip side guided surface 24 and the outer ring groove shoulder 13, so that the contact resistance between the cage 7 and the outer ring 3 can be kept extremely small. Therefore, it is possible to prevent abnormal heat generation due to the sliding resistance of the contact portion between the cage 7 and the outer ring 3.

[0051] Here, the lubrication state between the sliding surfaces is classified into boundary lubrication and hydrodynamic lubrication. In the boundary lubrication state, several molecular layers (10 -5 ~10 -6 The term refers to a state in which the sliding surfaces are lubricated with an oil film of about 10 mm, and the fine projections and recesses of the sliding surfaces come into direct contact with each other. On the other hand, in a hydrodynamic lubrication state, the wedge film effect creates an oil film (for example, 10 -3 ~10 -1 This refers to a state in which a wedge film effect (approximately 1 / 2 mm) is formed between the sliding surfaces, and the oil film prevents direct contact between the sliding surfaces (only indirect contact occurs via the oil film). When the wedge film effect occurs and a fluid lubrication state is established, sliding resistance becomes nearly zero, making it possible to operate at high peripheral speeds that were previously impossible.

[0052] 1, in this ball bearing 1, one of a pair of outer ring groove shoulders 13 (the right outer ring groove shoulder 13) supports the retainer annular portion 21 from the radial outside, and the other outer ring groove shoulder 13 (the left outer ring groove shoulder 13) supports the axial end portion on the tip side of the retainer claw portion 22 from the radial outside, so that the retainer claw portion 22 is less likely to bend radially outward. Therefore, even when used at high speed rotation, torsional deformation of the retainer annular portion 21 due to the centrifugal force received by the retainer claw portion 22 can be suppressed, and the retainer claw portion 22 itself can also be suppressed from being bent radially outward.

[0053] In addition, as shown in Figure 3, this ball bearing 1 has R-chamfered axial end edge 25 of the root side guided surface 23 away from the retainer claw portion 22 and axial end edge 26 of the tip side guided surface 24 away from the retainer annular portion 21.This allows an oil film to be effectively formed between the root side guided surface 23 and one of the outer ring groove shoulders 13 (the right side outer ring groove shoulder 13) shown in Figure 1 by means of a wedge film effect, and also allows an oil film to be effectively formed between the tip side guided surface 24 and the other outer ring groove shoulder 13 (the left side outer ring groove shoulder 13) by means of a wedge film effect.

[0054] 2, in this ball bearing 1, the portion of the circumferentially opposing surface 27 that circumferentially receives the balls 5 has a planar shape extending parallel to the line connecting the center of the retainer annular portion 21 and the center of the retainer claw portions 22, so that when the retainer claw portions 22 move radially outward due to the centrifugal force acting on the retainer claw portions 22, the circumferentially opposing surface 27 of the retainer claw portions 22 can be prevented 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 retainer claw portions 22 and the balls 5 is kept low, heat generation in the ball bearing 1 can also be suppressed.

[0055] In addition, since the ball bearing 1 has an open axial end opposite the axial end of the annular space 4 blocked by the sealing member 6, it is possible to sufficiently lubricate the base side guided surface 23 and the tip side guided surface 24, thereby reliably forming an oil film in the form of a wedge film.

[0056] In the above embodiment, an oil-lubricated ball bearing 1 using lubricating oil as the lubricant for lubricating the inside of the bearing has been described as an example, but the present invention is also applicable to a grease-lubricated ball bearing 1 using grease as the lubricant for lubricating the inside of the bearing. Grease is a semi-solid lubricant that contains lubricating oil and a thickener dispersed in the lubricating oil.

[0057] 10 to 13 show a ball bearing 1 according to the second embodiment. The same reference numerals are used to designate parts corresponding to those in the first embodiment, and the description thereof will be omitted.

[0058] 10 and 12, an oil reservoir groove 40 is formed on the radially inner surface of the cage claw portion 22, extending in the axial direction from the tip of the cage claw portion 22 toward the cage annular portion 21. As shown in Fig. 10, the oil reservoir groove 40 is cut up into the radially inner surface of the cage 7 at a position radially opposing the inner ring groove shoulder 9 of the pair of inner ring groove shoulders 9 that is closer to the cage annular portion 21. In other words, the oil reservoir groove 40 is a groove that does not penetrate in the axial direction. Note that the oil reservoir groove 40 can also be formed so as to penetrate the radially inner surface of the cage 7 in the axial direction.

[0059] 11 and 13, the oil reservoir groove 40 is formed in the circumferential center of the radially inner surface of the cage claw portion 22. The oil reservoir groove 40 has a semicircular cross-sectional shape. The oil reservoir groove 40 may have a triangular cross-sectional shape or a rectangular cross-sectional shape.

[0060] The ball bearing 1 of this embodiment is capable of collecting lubricating oil that is scattered to the outer diameter side by centrifugal force in the oil collecting groove 40 and supplying the lubricating oil to the inner ring 2.

[0061] Moreover, the ball bearing 1 of this embodiment has the same functions and effects as the first embodiment.

[0062] 14 to 17 show a ball bearing 1 according to a third embodiment. The same reference numerals are used to designate parts corresponding to those in the first and second embodiments, and the description thereof will be omitted.

[0063] 17, an escape recess 41 is formed in a portion of the radial outer surface of the retainer claw portion 22 between the root side guided surface 23 and the tip side guided surface 24. That is, the radial outer surface of the retainer claw portion 22 is a stepped surface in which the root side guided surface 23, the escape recess 41, and the tip side guided surface 24 are arranged in order along the axial direction.

[0064] As shown in Figs. 14 and 15, the relief recess 41 extends in the circumferential direction with an axial width wider than the axial width of the outer ring raceway groove 12. Here, as shown in Fig. 14, the relief recess 41 is arranged so as to cover the entire axial width of the outer ring raceway groove 12. That is, the end of the relief recess 41 on the side of the base side guided surface 23 is arranged at a position shifted toward the one outer ring groove shoulder 13 from the boundary portion between the outer ring raceway groove 12 and one of the pair of outer ring groove shoulders 13 (the outer ring groove shoulder 13 on the side closer to the cage annular portion 21). Also, the end of the relief recess 41 on the side of the tip side guided surface 24 is arranged at a position shifted toward the other outer ring groove shoulder 13 from the boundary portion between the outer ring raceway groove 12 and the other of the pair of outer ring groove shoulders 13 (the outer ring groove shoulder 13 on the side farther from the cage annular portion 21). Both axial ends of the relief recess 41 are inclined and cut up to the base side guided surface 23 and the tip side guided surface 24 .

[0065] 15, the relief recess 41 is recessed with respect to the root side guided surface 23 (or the tip side guided surface 24) so ​​that the inner surface is located at a position set back radially inward from the root side guided surface 23 (or the tip side guided surface 24). The inner surface of the relief recess 41 is a flat surface perpendicular to the radial direction in the drawing.

[0066] 14, the ball bearing 1 of this embodiment has an escape recess 41 formed between the root side guided surface 23 and the tip side guided surface 24, so that the boundary portion between the outer ring groove shoulder 13 and the outer ring raceway groove 12 can be prevented from sliding against the radially outer surface of the cage annular portion 21 or the radially outer surface of the cage claw portions 22. Therefore, it is possible to prevent the radially outer surface of the cage annular portion 21 or the radially outer surface of the cage claw portions 22 from wearing locally at the position corresponding to the boundary portion between the outer ring groove shoulder 13 and the outer ring raceway groove 12.

[0067] Moreover, the ball bearing 1 of this embodiment has the same functions and effects as the first and second embodiments.

[0068] 18 and 19 show a ball bearing 1 according to a fourth embodiment. The same reference numerals are used to designate parts corresponding to those in the first embodiment, and the description thereof will be omitted.

[0069] 18, the axial thickness of retainer annular portion 21 is approximately the same as the axial spacing between balls 5 and seal member 6 (specifically, 95% or more and less than 100% of the axial spacing between balls 5 and seal member 6). Retainer annular portion 21 has a retainer-side sliding surface 42 that faces and slides against seal member 6 in the axial direction, and seal member 6 has a seal-side sliding surface 43 that slides against retainer-side sliding surface 42.

[0070] As shown in Fig. 19, a plurality of axial protrusions 44 are formed at a constant pitch in the circumferential direction on the cage-side sliding contact surface 42. Each axial protrusion 44 is formed so that its cross-sectional shape along the circumferential direction is an axially convex arc shape. The axial height of each axial protrusion 44 is set to 5% or less of the circumferential width dimension of each axial protrusion 44. In the figure, the axial height of each axial protrusion 44 is exaggerated to make the presence of each axial protrusion 44 easier to understand. On the other hand, the seal-side sliding contact surface 43 is an annular flat surface perpendicular to the axial direction, and no axial protrusions 44 are formed thereon.

[0071] 18, the axial protrusion 44 is disposed at a position overlapping the pitch circle of the balls 5 (a virtual circle connecting the centers of the multiple balls 5) or radially outward from the pitch circle. Here, "the axial protrusion 44 is disposed at a position overlapping the pitch circle of the balls 5" means that the virtual cylindrical surface passing through the pitch circle of the balls 5 passes through the position of the axial protrusion 44, and "the axial protrusion 44 is disposed radially outward from the pitch circle of the balls 5" means that the entire axial protrusion 44 is radially outward from the virtual cylindrical surface passing through the pitch circle of the balls 5. In the figure, the axial protrusion 44 is disposed radially outward from the pitch circle of the balls 5.

[0072] The axial projection 44 has a parallel apex 45, a first inclined apex 46, and a second inclined apex 47. The parallel apex 45 is a portion in which the height of the axially convex arc-shaped apex in the cross section along the circumferential direction is constant along the radial direction. The first inclined apex 46 is a portion in which the height of the axially convex arc-shaped apex in the cross section along the circumferential direction gradually decreases from the radial outer end of the parallel apex 45 toward the radial outward direction. The second inclined apex 47 is a portion in which the height of the axially convex arc-shaped apex in the cross section along the circumferential direction gradually decreases from the radial inner end of the parallel apex 45 toward the radial inward direction. As shown in FIG. 18, the first inclined apex 46 has a cross-sectional shape perpendicular to the circumferential direction that is R-shaped so as to smoothly connect with the parallel apex 45. The second inclined apex 47 also has a cross-sectional shape perpendicular to the circumferential direction that is R-shaped so as to smoothly connect with the parallel apex 45.

[0073] 19, this ball bearing 1 has a plurality of axial protrusions 44, each of which has an axially convex arc-shaped cross section along the circumferential direction and is formed at a constant pitch on the cage-side sliding surface 42, so that an oil film is formed between the axial protrusions 44 and the seal-side sliding surface 43 due to the wedge film effect, and this oil film creates a fluid lubrication state between the axial protrusions 44 and the seal-side sliding surface 43, making it possible to keep the contact resistance between the cage 7 and the seal member 6 extremely small. As a result, abnormal heat generation due to the sliding resistance at the contact points between the cage 7 and the seal member 6 can be prevented.

[0074] 18, the ball bearing 1 has the retainer annular portion 21 in sliding contact with the seal member 6, which makes it possible to set the axial thickness of the retainer annular portion 21 large and increase the rigidity of the retainer annular portion 21. Therefore, even when used at high speeds, torsional deformation of the retainer annular portion 21 due to the centrifugal force applied to the retainer claw portions 22 can be suppressed.

[0075] Furthermore, this ball bearing 1 can be installed in locations where the space for installing the bearing is narrow and it is necessary to keep the width dimension of the bearing small (i.e., locations where, in the past, it was necessary to give up on using a sealed ball bearing and adopt an open-type ball bearing with both axial ends open without a sealing member 6).

[0076] In addition, as shown in Fig. 18, this ball bearing 1 employs an axial protrusion 44 having a parallel apex 45 and a first inclined apex 46, so that when the bearing rotates at a low speed and the centrifugal force received by the cage claw portion 22 is relatively small, an oil film can be formed between the parallel apex 45 of the axial protrusion 44 and the seal-side sliding surface 43 due to the wedge film effect. When the bearing rotates at a high speed and the centrifugal force received by the cage claw portion 22 is relatively large, an oil film can be formed between the parallel apex 45 and the first inclined apex 46 of the axial protrusion 44 and the seal-side sliding surface 43 due to the wedge film effect, in a state in which the cage annular portion 21 has undergone a relatively large torsional deformation. In this way, an oil film can be stably formed between the cage 7 and the seal member 6 due to the wedge film effect, regardless of the rotation speed of the bearing.

[0077] Furthermore, as shown in FIG. 18, in this ball bearing 1, the cross-sectional shape perpendicular to the circumferential direction of the first inclined apex 46 is R-shaped, and the first inclined apex 46 and the parallel apex 45 are smoothly connected. Therefore, when an oil film is formed between the parallel apex 45 and the first inclined apex 46 and the seal side sliding surface 43 due to the wedge film effect when the retainer annular portion 21 is subjected to relatively large torsional deformation, the oil film can be formed stably.

[0078] Furthermore, as shown in Figure 18, in this ball bearing 1, the axial protrusion 44 is positioned at a position overlapping with the pitch circle of the balls 5 or radially outward therefrom. Therefore, when the centrifugal force acting on the retainer claw portion 22 causes torsional deformation in the retainer annular portion 21 in a direction that tilts the retainer claw portion 22 radially outward, the torsional deformation can be prevented from causing the retainer side sliding surface 42 and the seal side sliding surface 43 to come into contact at a position that is radially outward of the axial protrusion 44.

[0079] Moreover, the ball bearing 1 of this embodiment has the same effects as those of the first embodiment. Furthermore, it is possible to add the configurations of the second and third embodiments to the ball bearing 1 of this embodiment.

[0080] 20 and 21 show a ball bearing 1 according to the fifth embodiment. The fourth embodiment differs in that an axial protrusion 44 is provided on the cage-side sliding surface 42 out of the cage-side sliding surface 42 and the seal-side sliding surface 43, whereas the fifth embodiment differs in that an axial protrusion 44 is provided on the seal-side sliding surface 43, but the rest of the configuration is the same. Therefore, parts corresponding to those in the fourth embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0081] As shown in FIG. 21, a plurality of axial protrusions 44 are formed at a constant pitch in the circumferential direction on the seal side sliding surface 43. The axial protrusions 44 are molded in a mold on the rubber material 17 constituting the seal member 6. Each axial protrusion 44 is formed so that its cross-sectional shape along the circumferential direction is an axially convex arc shape. The axial height of the axial protrusions 44 is set to 5% or less of the circumferential width dimension of the axial protrusions 44. In the drawing, the axial height of the axial protrusions 44 is exaggerated to make the presence of the axial protrusions 44 easier to understand. On the other hand, the cage side sliding surface 42 is an annular flat surface perpendicular to the axial direction, and no axial protrusions 44 are formed.

[0082] As shown in FIG. 20, the axial projection 44 is disposed at a position overlapping with the pitch circle of the balls 5 (an imaginary circle connecting the centers of the plurality of balls 5) or radially outward from the pitch circle.

[0083] The axial projection 44 has a parallel apex 45, a first inclined apex 46, and a second inclined apex 47. The parallel apex 45 is a portion in which the height of the axially convex arc-shaped apex in the cross section along the circumferential direction is constant along the radial direction. The first inclined apex 46 is a portion in which the height of the axially convex arc-shaped apex in the cross section along the circumferential direction gradually decreases from the radial outer end of the parallel apex 45 toward the radial outward direction. The second inclined apex 47 is a portion in which the height of the axially convex arc-shaped apex in the cross section along the circumferential direction gradually decreases from the radial inner end of the parallel apex 45 toward the radial inward direction. The first inclined apex 46 has a cross-sectional shape perpendicular to the circumferential direction that is R-shaped so as to smoothly connect with the parallel apex 45. The second inclined apex 47 also has a cross-sectional shape perpendicular to the circumferential direction that is R-shaped so as to smoothly connect with the parallel apex 45.

[0084] 21, this ball bearing 1 has a plurality of axial protrusions 44, each of which has an axially convex arc-shaped cross section along the circumferential direction and is formed at a constant pitch on the seal-side sliding surface 43, so that an oil film is formed between the axial protrusions 44 and the cage-side sliding surface 42 due to the wedge film effect, and this oil film creates a fluid lubrication state between the axial protrusions 44 and the cage-side sliding surface 42, making it possible to keep the contact resistance between the cage 7 and the seal member 6 extremely small. As a result, abnormal heat generation due to the sliding resistance at the contact points between the cage 7 and the seal member 6 can be prevented.

[0085] As shown in Fig. 20, this ball bearing 1 employs an axial protrusion 44 having a parallel apex 45 and a first inclined apex 46, so that when the bearing rotates at a low speed and the centrifugal force received by the cage claw portion 22 is relatively small, an oil film can be formed between the parallel apex 45 of the axial protrusion 44 and the cage-side sliding surface 42 due to the wedge film effect. When the bearing rotates at a high speed and the centrifugal force received by the cage claw portion 22 is relatively large, an oil film can be formed between the parallel apex 45 and the first inclined apex 46 of the axial protrusion 44 and the cage-side sliding surface 42 due to the wedge film effect, in a state in which the cage annular portion 21 has undergone a relatively large torsional deformation. In this way, an oil film can be stably formed between the cage 7 and the seal member 6 due to the wedge film effect, regardless of the rotation speed of the bearing.

[0086] Furthermore, as shown in FIG. 20, in this ball bearing 1, the cross-sectional shape perpendicular to the circumferential direction of the first inclined apex 46 is R-shaped, and the first inclined apex 46 and the parallel apex 45 are smoothly connected. Therefore, when an oil film is formed between the parallel apex 45 and the first inclined apex 46 and the retainer side sliding surface 42 due to the wedge film effect when the retainer annular portion 21 undergoes a relatively large torsional deformation, the oil film can be formed stably.

[0087] Other functions and effects are the same as those of the fourth embodiment.

[0088] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0089] 1 ball bearing 2. Inner Circle 3 Outer ring 4. Annular Space 5 balls 6 Sealing material 7 Plastic cage 12 Outer ring raceway groove 13 Outer ring groove shoulder 21 Retainer ring part 22 Cage claw part 23 Root side guided surface 24 Tip side guided surface 25,26 Axial edge 27 Circumferential opposing surface 30 Transmission for electric vehicles 31 Electric motor 40 Oil Reservoir Groove 41 Relief recess 42 Cage side sliding surface 43 Seal side sliding surface 44 Axial projection 45 Parallel top 46 First Slope Top

Claims

1. Inner circle (2) and an outer ring (3) provided coaxially on the radially outer side of the inner ring (2); A plurality of balls (5) are assembled in an annular space (4) formed between the inner ring (2) and the outer ring (3); A resin cage (7) that holds the plurality of balls (5), An outer ring raceway groove (12) with which the balls (5) roll and come into contact is provided on an inner periphery of the outer ring (3), and a pair of outer ring groove shoulders (13) are located on both axial sides of the outer ring raceway groove (12), The resin retainer (7) has a retainer annular portion (21) extending in the circumferential direction adjacent to a passing area of ​​the balls (5), and a cantilever-shaped retainer claw portion (22) extending in the axial direction from the retainer annular portion (21) between the balls (5) adjacent in the circumferential direction, The axial length of the cage claw portion (22) is set to be greater than the axial width of the outer ring raceway groove (12), a base-side guided surface (23) that is in sliding contact with one of the pair of outer ring groove shoulders (13) is formed on a radially outer surface of the retainer annular portion (21); a tip-side guided surface (24) that is in sliding contact with the other of the pair of outer ring groove shoulder portions (13) is formed on a radially outer surface of an axial end portion on a tip side of the cage claw portion (22); The base side guided surface (23) and the tip side guided surface (24) have a cross-sectional shape along the circumferential direction formed into an arc shape that protrudes radially outward, a radius of curvature of a cross section along a circumferential direction of the base side guided surface (23) and the tip side guided surface (24) is set to be smaller than 1 / 2 of a radius of an inner diameter of the outer ring groove shoulder portion (13) and larger than 1 / 10 of a radius of an inner diameter of the outer ring groove shoulder portion (13); The annular space (4) has an opening at one end in the axial direction, and an annular seal member (6) is provided to close the opening at one end of the annular space (4). The retainer annular portion (21) has a retainer-side sliding surface (42) which is in sliding contact with the seal member (6) while facing the retainer in the axial direction, The seal member (6) has a seal-side sliding surface (43) that is in sliding contact with the cage-side sliding surface (42), a plurality of axial projections (44) having an axially convex arc-shaped cross-sectional shape along the circumferential direction are formed at a constant pitch on one of the retainer-side sliding contact surface (42) and the seal-side sliding contact surface (43); The ball bearing is characterized in that the axial protrusion (44) has a parallel apex (45) in which the height of the axially convex arc-shaped apex in a cross section taken along the circumferential direction is constant along the radial direction, and an inclined apex (46) in which the height of the axially convex arc-shaped apex in a cross section taken along the circumferential direction gradually decreases from the radial outer end of the parallel apex (45) toward the radial outward direction.

2. The cage claw portion (22) has a circumferentially opposing surface (27) that faces the ball (5) in the circumferential direction, 2. A ball bearing as described in claim 1, wherein the portion of the circumferential opposing surface (27) that receives the balls (5) in the circumferential direction has a planar shape extending parallel to a straight line connecting the center of the retainer annular portion (21) and the center of the retainer claw portion (22) so that the circumferential opposing surface (27) does not interfere with the balls (5) when the retainer claw portion (22) moves radially outward due to centrifugal force.

3. 3. A ball bearing as claimed in claim 1 or 2, wherein an axial end edge (25) of the base side guided surface (23) remote from the retainer claw portion (22) and an axial end edge (26) of the tip side guided surface (24) remote from the retainer annular portion (21) are R-chamfered.

4. A ball bearing as described in any one of claims 1 to 3, wherein an escape recess (41) extending circumferentially with an axial width wider than the axial width of the outer ring raceway groove (12) is formed between the root side guided surface (23) and the tip side guided surface (24) on the radial outer surface of the retainer claw portion (22).

5. A ball bearing as described in any one of claims 1 to 4, wherein an oil reservoir groove (40) is formed on the radially inner surface of the retainer claw portion (22), extending axially from the tip of the retainer claw portion (22) toward the retainer annular portion (21).

6. 6. The ball bearing according to claim 1, wherein the inclined apex portion (46) has a cross-sectional shape perpendicular to the circumferential direction that is an R-shape that smoothly connects to the parallel apex portion (45).

7. 7. A ball bearing according to claim 1, wherein the plurality of axial projections (44) are arranged at a position overlapping with a pitch circle of the balls (5) or radially outward therefrom.

8. A ball bearing as described in any one of claims 1 to 7, wherein the axial end of the annular space (4) opposite to the axial end blocked by the sealing member (6) is open without a sealing member (6) so as to receive lubricant supplied from the outside into the annular space (4).

9. 9. The ball bearing according to claim 1, which is used as a bearing for an electric vehicle transmission (30) that reduces the rotation of an electric motor (31) of the electric vehicle.

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