Sealed ball bearing

Abstract

To provide a ball bearing with a seal suitable for use at high speed rotation.SOLUTION: In a ball bearing with a seal, a seal side sliding surface 34 is formed with a plurality of axial projections 36 at intervals in a circumferential direction, each axial projection 36 has a sliding contact tip surface 37 extending linearly in a radial direction in a cross-sectional view perpendicular to the circumferential direction, a holder side sliding surface 35 is formed with a sliding contact flat surface 38 that slides in sliding contact with the sliding contact tip surface 37 when the bearing rotates, and the sliding contact tip surface 37 and the sliding contact flat surface 38 are arranged so as to face each other in a non-parallel manner at an angle α in a direction in which a gap widens from a radially inner side to a radially outer side when the bearing is stationary.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a sealed ball bearing in which a seal member is provided between an inner ring and an outer ring.

Background Art

[0002] Ball bearings are widely used as bearings for supporting rotating shafts of automobiles, industrial machines, and the like. Generally, a ball bearing has an inner ring, an outer ring coaxially provided on the radially outer side of the inner ring, a plurality of balls provided in an annular space between the inner ring and the outer ring, and a cage for holding the plurality of balls.

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

[0004] Also, for example, as in Patent Document 2, in order to prevent foreign matter from entering from the outside to the inside of the ball bearing or to prevent lubricant (such as lubricating oil or grease) from leaking from the inside to the outside of the ball bearing, a sealed ball bearing in which an axial end opening of an annular space formed between the inner ring and the outer ring is closed by an annular seal member may be used.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, in the field of electric vehicles such as EVs (battery electric vehicles) and HEVs (hybrid electric vehicles), in order to reduce the size and weight of electric motors, the rotational speed of electric motors has been increased. The ball bearing that supports the rotating shaft to which the rotation of such an electric motor is input has a dmn value (pitch circle diameter dm (mm) of the balls × rotational speed n (min -1 )) may also be used under the condition that it exceeds 2 million.

[0007] The inventors of the present application considered using a crowned cage for the ball bearing that supports the high-speed rotating shaft of an EV or HEV.

[0008] However, when using a crowned cage for a high-speed rotating ball bearing, due to the centrifugal force acting on the cantilever beam-shaped cage claw portion, torsional deformation in the direction of tilting the cage claw portion radially outward occurs in the cage ring portion, and it has been found that this deformation may cause the cage claw portion to interfere with the balls. When the cage claw portion interferes with the balls, it causes heat generation in the ball bearing.

[0009] In particular, when the bearing using a crowned cage is also a sealed ball bearing, if the cage ring portion of the crowned cage comes into contact with the seal member, there is a risk of abnormal heat generation due to the sliding resistance at the contact portion. Therefore, it is necessary to suppress the axial width dimension of the cage ring portion so that the cage ring portion does not come into contact with the seal member. For this reason, it is difficult to increase the rigidity of the cage ring portion, and torsional deformation is likely to occur in the cage ring portion due to the centrifugal force acting on the cage claw portion, and the cage claw portion is likely to interfere with the balls.

[0010] Thus, when using a crowned cage for a sealed ball bearing, it has been difficult to use such a sealed ball bearing for high-speed rotation applications. Also, when the space at the bearing installation site is narrow and it is necessary to keep the width dimension of the bearing small, it is difficult to avoid the crowned cage from contacting the seal member. Therefore, in some cases, it has been necessary to abandon the use of a sealed ball bearing and adopt an open-type ball bearing with both axial ends open without a seal member.

[0011] The problem to be solved by this invention is to provide a sealed ball bearing suitable for use at high speeds.

Means for Solving the Problem

[0012] To solve the above problem, this invention adopts the following configuration for a sealed ball bearing. An inner ring, An outer ring coaxially provided on the radially outer side of the inner ring, A plurality of balls incorporated in an annular space formed between the inner ring and the outer ring, An annular seal member provided at one end opening in the axial direction of the annular space, A cage for holding the plurality of balls, and having, In a sealed ball bearing having a cage annular portion that extends in the circumferential direction in a region axially sandwiched between the ball passing region and the seal member, and a cantilever beam-shaped cage claw portion that extends in the axial direction between the balls adjacent in the circumferential direction from the cage annular portion, The seal member has a seal-side sliding surface that faces the cage in the axial direction, The cage has a cage-side sliding surface that faces the seal-side sliding surface in the axial direction, On one of the sliding surfaces of the seal-side sliding surface and the cage-side sliding surface, a plurality of axial protrusions are formed at intervals in the circumferential direction, Each of the axial protrusions has a sliding contact tip surface that extends linearly in the radial direction in a cross-sectional view perpendicular to the circumferential direction, On the other sliding surface, a smooth sliding contact plane is formed over the entire circumference by sliding contact with the sliding contact tip surface during bearing rotation, The sealed ball bearing is characterized in that the sliding contact tip surface and the sliding contact plane are arranged non-parallel to each other at an angle in a direction in which the interval widens from the radially inner side to the radially outer side when the bearing is stationary.

[0013] By doing so, when the bearing rotates, when the sliding contact tip surface of the axial protrusion formed on one of the sliding surfaces on the seal side and the sliding surface on the cage side slides on the smooth sliding contact plane formed over the entire circumference of the other sliding surface, since the sliding contact tip surface of the axial protrusion has a shape that linearly extends in the radial direction, it is difficult for the lubricating oil to be scraped off by the axial protrusion, and the lubricating oil is easily drawn into the sliding contact portion of the axial protrusion. Therefore, an oil film due to the wedge film effect is formed between the sliding contact tip surface of the axial protrusion and the sliding contact plane, and the sliding contact tip surface and the sliding contact plane are in a fluid lubrication state due to the oil film, and the contact resistance between the cage and the seal member can be extremely reduced.

[0014] Also, since the sliding contact tip surface and the sliding contact plane are arranged to face each other non-parallelly with an angle in the direction in which the interval widens from the radially inner side to the radially outer side when the bearing is stationary, when the bearing rotates at high speed, it is possible to stably form an oil film due to the wedge film effect between the sliding contact tip surface and the sliding contact plane. That is, assuming a configuration in which the sliding contact tip surface and the sliding contact plane face each other parallelly when the bearing is stationary, when the bearing rotates at high speed, the cage ring portion is deformed by the centrifugal force acting on the cage claw portion, and due to this deformation, the cage-side sliding surface is inclined, and the sliding contact tip surface and the sliding contact plane become non-parallel, so there is a problem that it becomes difficult to form an oil film due to the wedge film effect between the sliding contact tip surface and the sliding contact plane. To solve this problem, if a configuration is adopted in which the sliding contact tip surface and the sliding contact plane face each other non-parallelly with an angle in the direction in which the interval widens from the radially inner side to the radially outer side when the bearing is stationary, when the bearing rotates at high speed, the cage ring portion is deformed by the centrifugal force acting on the cage claw portion, and due to this deformation, the sliding contact tip surface and the sliding contact plane approach parallel to each other, so it is possible to stably form an oil film due to the wedge film effect between the sliding contact tip surface and the sliding contact plane.

[0015] The angle formed by the sliding contact tip surface and the sliding contact plane when the bearing is stationary can be set in the range of 0.5° or more and 6° or less.

[0016] The axial length of the cage claw portion is set to be larger than the radius of the ball. When the retainer claw portion has a pocket side surface facing the ball in the circumferential direction, It is preferable to adopt a configuration in which the portion of the pocket side surface that receives the ball in the circumferential direction has a planar shape so that the pocket side surface does not interfere with the ball when the retainer claw portion moves radially outward due to centrifugal force.

[0017] In this way, when the bearing rotates at high speed, when the retainer ring portion is deformed by the centrifugal force acting on the retainer claw portion and the retainer claw portion moves radially outward due to the deformation, it is possible to prevent the pocket side surface of the retainer claw portion from interfering with the ball and causing abnormal heat generation.

[0018] The pocket side surface can adopt a plane along a straight line extending radially through the center of the bearing.

[0019] Also, as the pocket side surface, a plane along parallel straight lines facing each other in the circumferential direction with the straight line connecting the center of the bearing and the circumferential center of the retainer claw portion in between can be adopted.

[0020] In this way, even if the retainer claw portion moves radially along the straight line connecting the center of the bearing and the circumferential center of the retainer claw portion, the distance between the ball and the pocket side surface does not change. Therefore, when the bearing rotates at high speed, even when the retainer ring portion is deformed by the centrifugal force acting on the retainer claw portion and the retainer claw portion moves radially outward due to the deformation, the holding of the ball by the retainer becomes stable.

[0021] The retainer ring portion has a pocket bottom surface facing the ball in the axial direction, The pocket bottom surface has a shape that extends linearly in the radial direction in a cross-sectional view perpendicular to the circumferential direction, It is possible to adopt a configuration in which the pocket side surface and the pocket bottom surface are connected in a concave arc shape when viewed from the radial direction.

[0022] By doing so, since the pocket side surface and the pocket bottom surface are connected in a concave arc shape, it is possible to secure the cross-sectional area of the base portion in the axial direction of the cage claw portion while suppressing the mass of the tip portion in the axial direction of the cage claw portion to a small value. Therefore, it is possible to effectively suppress the deflection of the cage claw portion due to the centrifugal force acting on the cage claw portion.

[0023] It is preferable to form a build-up portion that bulges axially inward without contacting the ball at the radially inner end of the pocket bottom surface.

[0024] By doing so, it becomes possible to effectively prevent the cage ring portion from being damaged due to the influence of centrifugal force. That is, when the cage ring portion is torsionally deformed by the centrifugal force acting on the cage claw portion, stress concentration is likely to occur in the radially inner portion (the radially inner end of the pocket bottom surface) corresponding to the middle of the circumferentially adjacent cage claw portions in the cage ring portion. Therefore, if a build-up portion that bulges axially inward is formed at the radially inner end of the pocket bottom surface, it becomes possible to effectively prevent the cage ring portion from being damaged due to the stress concentration caused by the centrifugal force.

[0025] An outer diameter side oil groove extending axially from the tip of the cage claw portion toward the cage ring portion is formed on the radially outer surface of the cage claw portion. An inner diameter side oil groove extending axially from the tip of the cage claw portion toward the cage ring portion is formed on the radially inner surface of the cage claw portion. It is preferable to adopt a configuration in which the cage claw portion has an H shape in which the cross-sectional shape perpendicular to the axial direction is open to the radially outer side and the radially inner side by the outer diameter side oil groove and the inner diameter side oil groove.

[0026] By doing so, the outer diameter side oil groove formed on the radially outer surface of the cage claw portion and the inner diameter side oil groove formed on the radially inner surface of the cage claw portion make the cross-sectional shape of the cage claw portion an H shape. Therefore, while ensuring the second moment of inertia of the cross-section of the cage claw portion (the resistance of the cage claw portion to deformation against the bending moment), the mass of the cage claw portion can be suppressed. As a result, when the bearing rotates at high speed, the torsional deformation of the cage ring portion caused by the centrifugal force received by the cage claw portion and the bending deformation of the cage claw portion itself can be suppressed to a small extent.

[0027] The outer diameter side oil groove is formed such that the position of the groove bottom surface of the outer diameter side oil groove gradually changes radially outward from the tip side to the root side of the cage claw portion. It is preferable to adopt a configuration in which a planar rising surface that rises radially outward from the root of the cage claw portion is formed on the cage ring portion.

[0028] By doing so, since the outer diameter side oil groove is formed such that the position of the groove bottom surface of the outer diameter side oil groove gradually changes radially outward from the tip side to the root side of the cage claw portion, when the bearing rotates, the lubricating oil in the outer diameter side oil groove moves from the tip side to the root side of the cage claw portion due to the pumping effect. Then, the lubricating oil that has moved in the outer diameter side oil groove from the tip side to the root side of the cage claw portion is returned axially inward by the rising surface that rises radially outward from the root of the cage claw portion. By repeating this action, it becomes possible to efficiently circulate the lubricating oil in the bearing.

[0029] A configuration can be adopted in which an outer diameter side through groove that penetrates the outer periphery of the cage ring portion in the axial direction is formed at a circumferential position corresponding to the cage claw portion.

[0030] By doing so, the lubricating oil can easily flow back and forth between the region axially inside the cage ring portion and the region axially outside the cage ring portion through the outer diameter side through groove, and the circulation of the lubricating oil inside the bearing can be promoted. Further, since the outer diameter side through groove is formed at the circumferential position corresponding to the cage claw portion in the cage ring portion (that is, the position where the rigidity is ensured by the cage claw portion in the cage ring portion), it is possible to effectively prevent the reduction in the rigidity of the cage ring portion due to the formation of the outer diameter side through groove.

[0031] Furthermore, it is preferable to adopt a configuration in which an axial groove that extends axially along the outer periphery of the cage ring portion is formed between the outer diameter side through grooves adjacent to each other in the circumferential direction, is open to the axially outer side of the cage ring portion, and is non-through on the axially inner side of the cage ring portion.

[0032] By doing so, the lubricating oil can easily flow back and forth between the region axially inside the cage ring portion and the region axially outside the cage ring portion through the axial groove, and the circulation of the lubricating oil inside the bearing can be promoted. Further, since the axial groove is formed non-through on the axially inner side of the cage ring portion, it is possible to effectively prevent the breakage of the cage ring portion due to stress concentration. That is, when the cage ring portion is torsionally deformed by the centrifugal force acting on the cage claw portion, stress concentration is likely to occur on the axially inner side of the outer periphery of the cage ring portion. Therefore, by forming the axial groove on the outer periphery of the cage ring portion to be non-through on the axially inner side, it is possible to effectively prevent the breakage of the cage ring portion due to stress concentration.

[0033] The axial length of the axial groove is preferably set to 2 / 3 or less of the axial width of the cage ring portion.

[0034] By doing so, it is possible to effectively prevent the reduction in the rigidity of the cage ring portion due to the formation of the axial groove on the outer periphery of the cage ring portion, and to effectively prevent the breakage of the cage ring portion due to stress concentration.

[0035] It is possible to adopt a configuration in which an inner diameter side through groove penetrating the inner circumference of the retainer ring portion in the axial direction is formed at a circumferential position corresponding to the retainer claw portion.

[0036] In this way, the lubricating oil can easily travel back and forth between the region axially inside the retainer ring portion and the region axially outside the retainer ring portion through the inner diameter side through groove, and the circulation of the lubricating oil inside the bearing can be promoted. Further, since the inner diameter side through groove is formed at a circumferential position corresponding to the retainer claw portion in the retainer ring portion (that is, the position where the rigidity is ensured by the retainer claw portion in the retainer ring portion), it is possible to effectively prevent the reduction in the rigidity of the retainer ring portion due to the formation of the inner diameter side through groove.

[0037] The seal member has a seal side inclined surface extending linearly and inclined axially inward from the seal side sliding surface toward the radially inner side in a cross-sectional view perpendicular to the circumferential direction. The retainer ring portion has a retainer side inclined surface extending linearly and inclined axially inward from the retainer side sliding surface toward the radially inner side and a chamfered portion extending linearly and inclined axially inward from the retainer side sliding surface toward the radially outer side in a cross-sectional view perpendicular to the circumferential direction. The angle formed by the retainer side inclined surface and the seal side inclined surface is set to 10° or less. It is preferable to adopt a configuration in which the angle formed by the chamfered portion and the seal side sliding surface is set to be greater than 10° and 48° or less.

[0038] In this way, the angle formed between the cage-side inclined surface and the seal-side inclined surface, which is formed radially inward of the sliding contact portion between the cage-side sliding surface and the seal-side sliding surface, is smaller than the angle formed between the chamfered portion formed radially outward of the sliding contact portion between the cage-side sliding surface and the seal-side sliding surface and the seal-side sliding surface. That is, the angle formed between the cage and the seal member radially inward of the sliding contact portion between the cage-side sliding surface and the seal-side sliding surface is smaller than the angle formed between the cage and the seal member radially outward of the sliding contact portion between the cage-side sliding surface and the seal-side sliding surface. Therefore, in the region axially sandwiched between the cage and the seal member, a flow of lubricating oil occurs from radially inward of the sliding contact portion between the cage-side inclined surface and the seal-side inclined surface toward radially outward of the sliding contact portion between the cage-side inclined surface and the seal-side inclined surface, enabling efficient lubrication within the bearing.

[0039] It is preferable to adopt a configuration in which notches penetrating in the circumferential direction are formed at the tips of the cage claws on both circumferential sides of the outer diameter side oil groove and the inner diameter side oil groove.

[0040] In this way, it becomes possible to increase the supply amount of lubricating oil to the balls from the circumferential direction and improve the lubrication performance of the balls.

[0041] The cage can adopt a resin cage.

[0042] The ball bearing with a seal having the above configuration is particularly suitable for use as a bearing for an electric motor of an electric vehicle or a bearing for an electric vehicle transmission that decelerates the rotation of the electric motor.

Advantages of the Invention

[0043] In the sealed ball bearing of the present invention, when the bearing rotates, the sliding contact tip surface of the axial protrusion formed on one of the sliding surfaces of the seal side sliding surface and the cage side sliding surface slides on the smooth sliding contact plane formed over the entire circumference of the other sliding surface. Since the sliding contact tip surface of the axial protrusion has a shape that linearly extends in the radial direction, it is difficult for the lubricating oil to be scraped off by the axial protrusion, and the lubricating oil is easily drawn into the sliding contact portion of the axial protrusion. Therefore, an oil film due to the wedge film effect is formed between the sliding contact tip surface of the axial protrusion and the sliding contact plane, and the space between the sliding contact tip surface and the sliding contact plane becomes a fluid lubrication state due to the oil film, and the contact resistance between the cage and the seal member can be suppressed to be extremely small.

[0044] Also, since the sliding contact tip surface and the sliding contact plane are arranged to face non-parallel with an angle in the direction in which the distance widens from the radially inner side to the radially outer side when the bearing is stationary, when the bearing rotates at high speed, it is possible to stably form an oil film due to the wedge film effect between the sliding contact tip surface and the sliding contact plane. That is, when the bearing rotates at high speed, the centrifugal force acting on the cage claw portion deforms the cage ring portion, and due to this deformation, the sliding contact tip surface and the sliding contact plane approach parallel to each other, so it is possible to stably form an oil film due to the wedge film effect between the sliding contact tip surface and the sliding contact plane.

Brief Description of the Drawings

[0045]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0046] FIG. 1 shows a sealed ball bearing 1 according to an embodiment of the present invention. This sealed ball bearing 1 includes an inner ring 2, an outer ring 3 coaxially provided on the radially outer side of the inner ring 2, a plurality of balls 5 incorporated at intervals in the circumferential direction in an annular space 4 formed between the inner ring 2 and the outer ring 3, a resin cage 6 (hereinafter simply referred to as "cage 6") that holds the circumferential intervals of the plurality of balls 5, an annular seal member 7 that closes one end opening (the right end opening in the figure) of the axial both ends of the annular space 4, and an annular seal member 8 that closes the other end opening (the left end opening in the figure). A lubricant (not shown) such as grease is enclosed in the annular space 4.

[0047] On the outer periphery of the inner ring 2, an inner ring raceway groove 9 with which the ball 5 rolls in contact, a pair of inner ring groove shoulders 10 located axially outside the inner ring raceway groove 9, and a pair of sliding recesses 11 located axially outside the inner ring groove shoulders 10 are formed. The inner ring raceway groove 9 is an arc groove having a concave arc-shaped cross section along the surface of the ball 5, and is formed by extending circumferentially at the axial center of the outer periphery of the inner ring 2. The pair of inner ring groove shoulders 10 are bank-like portions extending in the circumferential direction on both sides sandwiching the inner ring raceway groove 9 in the axial direction. The sliding recess 11 is a recess extending in the circumferential direction formed adjacent to the axially outer side of the inner ring groove shoulder 10. The seal members 7 and 8 are in sliding contact with the inner surfaces of the pair of sliding recesses 11, respectively.

[0048] On the inner circumference of the outer ring 3, there are formed an outer ring raceway groove 12 in which the balls 5 rollingly contact, a pair of outer ring groove shoulders 13 positioned axially outside the outer ring raceway groove 12, and a pair of seal fixing grooves 14 positioned axially outside the outer ring groove shoulders 13. The outer ring raceway groove 12 is an arc groove having a concave arc-shaped cross section along the surface of the ball 5, and is formed by extending circumferentially at the axial center of the inner circumference of the outer ring 3. The pair of outer ring groove shoulders 13 are bank-like portions extending circumferentially on both sides sandwiching the outer ring raceway groove 12 in the axial direction. The seal fixing groove 14 is a groove extending circumferentially formed adjacent to the axially outer side of the outer ring groove shoulder 13. Seal members 7 and 8 are respectively fitted and fixed in the seal fixing groove 14.

[0049] The balls 5 are radially sandwiched between the outer ring raceway groove 12 and the inner ring raceway groove 9. This sealed ball bearing 1 is a deep groove ball bearing. That is, the axial width dimension of the outer ring raceway groove 12 is larger than half of the diameter of the ball 5, and the axial width dimension of the inner ring raceway groove 9 is larger than half of the diameter of the ball 5.

[0050] As shown in FIG. 4, the seal member 7 is an annular member composed of an annular core metal 15 and a rubber material 16 (such as nitrile rubber, acrylic rubber, etc.) fixed to the core metal 15. The rubber material 16 is fixed to the core metal 15 by vulcanization insert molding. That is, by vulcanizing the rubber material 16 in a state where the core metal 15 is disposed in the mold for vulcanizing the rubber material 16, the rubber material 16 is adhered and fixed to the surface of the core metal 15.

[0051] The seal member 7 has a fitting portion 17 that fits into the seal fixing groove 14, an annular plate portion 18 that extends radially inward from the fitting portion 17, and a seal lip 19 that slidably contacts the inner surface of the sliding recess 11. The fitting portion 17 is provided at the outer diameter side end of the seal member 7. The seal lip 19 is provided at the inner diameter side end of the seal member 7. The surface of the inner surface of the sliding recess 11 where the seal lip 19 slidably contacts is a cylindrical surface having a constant outer diameter along the axial direction.

[0052] The retainer 6 has a retainer ring portion 20 (see Fig. 5) that extends in the circumferential direction in a region axially sandwiched between the passage region of the ball 5 and the seal member 7, and retainer claw portions 21 that extend axially between the balls 5 adjacent in the circumferential direction from the retainer ring portion 20. The retainer ring portion 20 and the retainer claw portions 21 are integrally formed without joints by a resin composition. As the resin composition forming the retainer ring portion 20 and the retainer claw portions 21, it is possible to use one composed only of a resin material, but here, one obtained by adding a fiber reinforcing material to the resin material is used.

[0053] As the resin material that forms the base of the resin composition, polyamide (PA) or super engineering plastic can be adopted. As the polyamide, polyamide 46 (PA46), polyamide 66 (PA66), polynonamethylene terephthalamide (PA9T), etc. can be used. Also, as the super engineering plastic, polyether ether ketone (PEEK), polyphenylene sulfide (PPS) can be adopted. As the fiber reinforcing material added to the resin material, glass fiber, carbon fiber, aramid fiber, etc. can be adopted.

[0054] The retainer claw portion 21 is formed in a cantilever beam shape with one end in the axial direction as a fixed end (the base of the retainer claw portion 21) fixed to the retainer ring portion 20 and the other end in the axial direction as a free end (the tip of the retainer claw portion 21). The axial length of the retainer claw portion 21 is set to be larger than the radius of the ball 5. The retainer claw portion 21 has a tapered shape in which the radial thickness gradually decreases from the side closer to the retainer ring portion 20 (the base side) toward the side farther away (the tip side).

[0055] As shown in Fig. 2, the cage claw portion 21 has a pocket side surface 22 that faces the ball 5 in the circumferential direction. The portion of the pocket side surface 22 that receives the ball 5 in the circumferential direction is formed in a planar shape so that the pocket side surface 22 does not interfere with the ball 5 when the cage claw portion 21 moves radially outward due to centrifugal force. As shown in Fig. 9, the pocket side surface 22 is a plane along a straight line L1 that extends radially through the bearing center O when viewed from the axial direction (that is, a plane that extends radially so that the bearing center O is located on the extension line of the pocket side surface 22).

[0056] As shown in Fig. 3, the portion of the pocket side surface 22 that receives the ball 5 in the circumferential direction has a straight shape that extends straight in the axial direction without a circumferential inclination when viewed from the radial direction so that no axial component force is generated when receiving the ball 5. The cage ring portion 20 has a pocket bottom surface 23 that faces the ball 5 in the axial direction. The pocket side surface 22 and the pocket bottom surface 23 are connected in a concave arc shape when viewed from the radial direction.

[0057] As shown in Fig. 5, the pocket bottom surface 23 is formed in a shape that extends linearly in the radial direction in a cross-sectional view perpendicular to the circumferential direction. At the radially inner end of the pocket bottom surface 23, a build-up portion 24 that bulges inward in the axial direction is integrally formed. The build-up portion 24 has a shape that protrudes radially inward within a range where contact with the ball 5 does not occur.

[0058] The cage 6 is a cage of an inner ring guiding type that is positioned radially by contact with the inner ring 2. On the inner circumference of the cage ring portion 20, a cage guided surface 42 that is guided by the inner ring groove shoulder portion 10 on the outer circumference of the inner ring 2 is formed. The cage guided surface 42 is an annular surface that is in sliding contact with and supported by the inner ring groove shoulder portion 10.

[0059] As shown in FIG. 4, on the radially outer surface 25 of the cage claw portion 21, an outer diameter side oil groove 26 extending axially from the tip of the cage claw portion 21 toward the cage ring portion 20 is formed. Further, on the radially inner surface 27 of the cage claw portion 21, an inner diameter side oil groove 28 extending axially from the tip of the cage claw portion 21 toward the cage ring portion 20 is formed. And the cage claw portion 21 has an H-shaped cross-sectional shape orthogonal to the axial direction, which is open to the radially outer side and the radially inner side, by the outer diameter side oil groove 26 and the inner diameter side oil groove 28.

[0060] The outer diameter side oil groove 26 is formed such that the position of the groove bottom surface of the outer diameter side oil groove 26 gradually changes radially outward from the tip side to the root side of the cage claw portion 21. Further, the inner diameter side oil groove 28 is formed such that the position of the groove bottom surface of the inner diameter side oil groove 28 gradually changes radially inward from the tip side to the root side of the cage claw portion 21. On the cage ring portion 20, a planar rising surface 29 rising radially outward from the root of the cage claw portion 21 is formed. The rising surface 29 is a plane orthogonal to the axial direction and intersects with an end portion on the root side of the cage claw portion 21 on the inner surface of the outer diameter side oil groove 26 with a step. Further, as shown in FIG. 6, the rising surface 29 also intersects with an end portion on the root side of the cage claw portion 21 on the radially outer surface 25 (the surface where the outer diameter side oil groove 26 is not formed) of the cage claw portion 21 with a step.

[0061] As shown in FIGS. 2 and 4, on the outer periphery of the cage ring portion 20, an outer diameter side through groove 30 penetrating the outer periphery of the cage ring portion 20 axially is formed at a circumferential position corresponding to the cage claw portion 21. Similarly, on the inner periphery of the cage ring portion 20, an inner diameter side through groove 31 penetrating the inner periphery of the cage ring portion 20 axially is formed at a circumferential position corresponding to the cage claw portion 21. The inner diameter side through groove 31 communicates with the inner diameter side oil groove 28 of the cage claw portion 21.

[0062] As shown in FIGS. 5 and 6, on the outer periphery of the cage ring portion 20, an axial groove 32 extending in the axial direction along the outer periphery of the cage ring portion 20 is formed between the outer diameter side through grooves 30 adjacent to each other in the circumferential direction. The axial groove 32 is open to the outside in the axial direction of the cage ring portion 20 and is formed so as to be non-penetrating to the inside in the axial direction of the cage ring portion 20. That is, the axial groove 32 is formed only in a portion of the outer periphery of the cage ring portion 20 from the axial intermediate portion to the axial outer end, and is not formed at the axial inner end of the outer periphery of the cage ring portion 20. The axial length of the axial groove 32 is set to be 2 / 3 or less of the axial width of the cage ring portion 20.

[0063] As shown in FIGS. 3 and 4, notches 33 penetrating in the circumferential direction are formed at the tips of the cage claw portions 21 on both circumferential sides of the outer diameter side oil groove 26 and the inner diameter side oil groove 28. By providing this notch 33, it becomes possible to increase the supply amount of lubricating oil from the circumferential direction to the balls 5 and improve the lubrication performance of the balls 5.

[0064] As shown in FIG. 4, the seal member 7 has a seal side sliding surface 34 facing the cage 6 in the axial direction. The seal side sliding surface 34 is an annular surface formed over the entire circumference on the inner side in the axial direction of the annular plate portion 18 of the seal member 7. The seal side sliding surface 34 is formed on the surface of the rubber material 16, not on the surface of the core metal 15. Further, the cage 6 has a cage side sliding surface 35 facing the seal side sliding surface 34 in the axial direction. The cage side sliding surface 35 is an annular surface formed over the entire circumference on the outer side in the axial direction of the cage ring portion 20.

[0065] As shown in FIG. 3, a plurality of axial protrusions 36 are formed at regular intervals in the circumferential direction on the seal side sliding surface 34. In the figure, in order to make the presence of the axial protrusions 36 easy to understand, the axial height of the axial protrusions 36 is exaggeratedly shown, but the axial height of the axial protrusions 36 is extremely small, 0.5 mm or less.

[0066] As shown in Fig. 7(a), each axial projection 36 has a sliding contact tip surface 37 that extends linearly in the radial direction in a cross-sectional view orthogonal to the circumferential direction. That is, the axial projection 36 has a shape in which the tops at the same height continuously extend in the radial direction, and the sliding contact tip surface 37 is formed by the tops. As shown in Fig. 8, the axial projection 36 is formed such that the cross-sectional shape orthogonal to the radial direction is an arc shape convex in the axial direction. The axial projection 36 may be formed such that the cross-sectional shape orthogonal to the radial direction is a trapezoidal shape convex in the axial direction.

[0067] On the other hand, as shown in Figs. 7(a) and 8, a smooth sliding contact plane 38 is formed over the entire circumference on the cage-side sliding surface 35. As shown in Fig. 7(a), the sliding contact tip surface 37 and the sliding contact plane 38 are arranged non-parallel with an angle α in a direction in which the interval widens from the radially inner side toward the radially outer side when the bearing is stationary. Here, the angle α formed by the sliding contact tip surface 37 and the sliding contact plane 38 when the bearing is stationary is set in the range of 0.5° or more and 6° or less (preferably 1° or more and 5° or less).

[0068] As shown in Fig. 4, the axial projection 36 is arranged at a position overlapping the pitch circle of the balls 5 (a virtual circle connecting the centers of the plurality of balls 5) or on the radially outer side thereof. Here, the axial projection 36 being arranged at a position overlapping the pitch circle of the balls 5 means that a virtual cylindrical surface passing through the pitch circle of the balls 5 has a positional relationship passing through the position of the axial projection 36, and the axial projection 36 being arranged on the radially outer side of the pitch circle of the balls 5 means that the entire axial projection 36 is in a positional relationship outside the virtual cylindrical surface passing through the pitch circle of the balls 5. In the figure, the axial projection 36 is arranged on the radially outer side of the pitch circle of the balls 5.

[0069] As shown in Fig. 7(a), the seal member 7 has a seal-side inclined surface 39 that extends linearly and inclines axially inward from the seal-side sliding surface 34 toward the radially inner side in a cross-sectional view orthogonal to the circumferential direction. The retainer ring portion 20 has a retainer-side inclined surface 40 that extends linearly and inclines axially inward from the retainer-side sliding surface 35 toward the radially inner side, and a chamfered portion 41 that extends linearly and inclines axially inward from the retainer-side sliding surface 35 toward the radially outer side in a cross-sectional view orthogonal to the circumferential direction.

[0070] The retainer-side inclined surface 40 and the seal-side inclined surface 39 face each other axially with an angle β in a direction in which the interval widens from the radially outer side toward the radially inner side. The angle β formed by the retainer-side inclined surface 40 and the seal-side inclined surface 39 is set to 10° or less. The chamfered portion 41 and the seal-side sliding surface 34 face each other axially with an angle γ such that the axial interval gradually widens from the radially inner side toward the radially outer side. The angle γ formed by the chamfered portion 41 and the seal-side sliding surface 34 is set to be greater than 10° and 48° or less.

[0071] As shown in Fig. 11, the above-described sealed ball bearing 1 can be used as a bearing for an electric vehicle transmission 50 that decelerates the rotation of an electric motor of an electric vehicle such as an EV (battery electric vehicle) or an HEV (hybrid electric vehicle). The bearing of this electric vehicle transmission 50 rotates at a wide range of rotational speeds from a low speed range to a high speed range during vehicle travel. When the bearing rotates at the highest speed, it is used under the condition that the dmn value (pitch circle diameter of the balls 5 (mm) × rotational speed (min -1 )) exceeds 2 million.

[0072] The transmission 50 shown in Fig. 11 includes a stator 52 of an electric motor 51, a rotor 53 of the electric motor 51, a rotating shaft 54 connected to the rotor 53, a sealed ball bearing 1 that rotatably supports the rotating shaft 54, a second rotating shaft 55 and a third rotating shaft 56 arranged in parallel with the rotating shaft 54, a first gear train 57 that transmits the rotation of the rotating shaft 54 to the second rotating shaft 55, and a second gear train 58 that transmits the rotation of the second rotating shaft 55 to the third rotating shaft 56. The stator 52 is an annular stationary member, and the rotor 53 as a rotating member is arranged inside the stator 52. When the stator 52 is energized, the rotor 53 rotates due to the electromagnetic force acting between the stator 52 and the rotor 53, and the rotation of the rotor 53 is input to the rotating shaft 54.

[0073] As shown in Figs. 7(b) and 8, in the sealed ball bearing 1 of this embodiment, when the bearing rotates and the sliding contact tip surface 37 of the axial protrusion 36 formed on the seal side sliding surface 34 slides on the smooth sliding contact plane 38 formed over the entire circumference of the cage side sliding surface 35, the sliding contact tip surface 37 of the axial protrusion 36 has a shape that extends linearly in the radial direction as shown in Fig. 7(b) (a shape in which the same height is continuous in the radial direction). Therefore, when the bearing rotates, it is difficult for the lubricating oil to be scraped away by the axial protrusion 36, and the lubricating oil is easily drawn into the sliding contact portion of the axial protrusion 36. Therefore, as shown in Fig. 8, an oil film is formed between the sliding contact tip surface 37 of the axial protrusion 36 and the sliding contact plane 38 due to the wedge film effect, and the sliding contact tip surface 37 and the sliding contact plane 38 are in a fluid lubrication state due to the oil film, and the contact resistance between the cage 6 and the seal member 7 can be suppressed to be extremely small. Therefore, it is possible to prevent abnormal heat generation due to the sliding resistance of the contact portion between the cage 6 and the seal member 7.

[0074] Here, the lubrication state between the sliding surfaces is classified into a boundary lubrication state and a fluid lubrication state. The boundary lubrication state refers to a state in which the sliding surfaces are lubricated by an oil film composed of several molecular layers (about 10 -5 ~10 -6 mm) of lubricating oil adsorbed on each sliding surface, and direct contact of the fine irregularities of the sliding surfaces occurs. On the other hand, the fluid lubrication state is an oil film (for example, 10 -3 ~10 -1(formed to a thickness of about several millimeters), and a state where direct contact between the sliding surfaces does not occur due to the oil film (only indirect contact through the oil film occurs). When the wedge film effect occurs and a fluid lubrication state is achieved, the sliding resistance becomes almost zero.

[0075] Further, as shown in FIG. 7(a), this sealed ball bearing 1 is arranged such that when the bearing is stationary, the sliding contact tip surface 37 and the sliding contact flat surface 38 face each other non-parallelly with an angle α in a direction where the interval widens from the radially inner side to the radially outer side. Therefore, when the bearing rotates at high speed, it is possible to stably form an oil film due to the wedge film effect between the sliding contact tip surface 37 and the sliding contact flat surface 38.

[0076] That is, assuming a configuration in which the sliding contact tip surface 37 and the sliding contact flat surface 38 shown in FIG. 7(a) face each other parallelly when the bearing is stationary, when the bearing rotates at high speed, the centrifugal force acting on the cage claw portion 21 shown in FIG. 4 deforms the cage ring portion 20, and due to this deformation, the cage-side sliding surface 35 tilts, and the sliding contact tip surface 37 and the sliding contact flat surface 38 become non-parallel. As a result, the sliding contact tip surface 37 hits the edge of the sliding contact flat surface 38, and there is a problem that it becomes difficult to form an oil film due to the wedge film effect between the sliding contact tip surface 37 and the sliding contact flat surface 38. To solve this problem, the sealed ball bearing 1 of the above embodiment adopts a configuration in which, as shown in FIG. 7(a), when the bearing is stationary, the sliding contact tip surface 37 and the sliding contact flat surface 38 face each other non-parallelly with an angle α in a direction where the interval widens from the radially inner side to the radially outer side. Therefore, when the bearing rotates at high speed, the centrifugal force acting on the cage claw portion 21 shown in FIG. 4 deforms the cage ring portion 20, and due to this deformation, as shown in FIG. 7(b), the sliding contact tip surface 37 and the sliding contact flat surface 38 approach parallel to each other. Thus, it is possible to stably form an oil film due to the wedge film effect between the sliding contact tip surface 37 and the sliding contact flat surface 38.

[0077] Further, as shown in FIGS. 2 and 9, in this sealed ball bearing 1, since the pocket side surface 22 is a plane along a straight line L1 extending radially through the bearing center O, when the bearing rotates at high speed, the centrifugal force acting on the cage claw portion 21 deforms the cage ring portion 20, and when the cage claw portion 21 moves radially outward due to this deformation, it is possible to prevent the pocket side surface 22 of the cage claw portion 21 from interfering with the ball 5 and causing abnormal heat generation.

[0078] As shown in FIG. 10, the pocket side surface 22 may adopt a plane along parallel straight lines L3 facing each other in the circumferential direction with the straight line L2 connecting the bearing center O and the circumferential center of the cage claw portion 21 in between. Even in this case, when the centrifugal force acting on the cage claw portion 21 deforms the cage ring portion 20 and the cage claw portion 21 moves radially outward due to this deformation, it is possible to prevent the pocket side surface 22 of the cage claw portion 21 from interfering with the ball 5 (see FIG. 2) and causing abnormal heat generation.

[0079] Also, when the pocket side surface 22 shown in FIG. 10 is adopted, when the cage claw portion 21 moves radially along the straight line L2 connecting the bearing center O and the circumferential center of the cage claw portion 21, the distance between the ball 5 (see FIG. 2) and the pocket side surface 22 does not change. Therefore, even when the centrifugal force acting on the cage claw portion 21 deforms the cage ring portion 20 and the cage claw portion 21 moves radially outward due to this deformation when the bearing rotates at high speed, the holding of the ball 5 by the cage 6 becomes stable.

[0080] Further, as shown in FIG. 3, in the sealed ball bearing 1 of the above embodiment, since the pocket side surface 22 and the pocket bottom surface 23 are connected in a concave arc shape, it is possible to secure the cross-sectional area of the root portion in the axial direction of the cage claw portion 21 while suppressing the mass of the tip portion in the axial direction of the cage claw portion 21 to be small. Therefore, it is possible to effectively suppress the deflection of the cage claw portion 21 due to the centrifugal force acting on the cage claw portion 21.

[0081] Further, as shown in FIGS. 5 and 6, this sealed ball bearing 1 forms a build-up portion 24 at the radially inner end of the pocket bottom surface 23, so it is possible to effectively prevent the cage ring portion 20 from being damaged due to the influence of centrifugal force. That is, when the cage ring portion 20 is torsionally deformed by the centrifugal force acting on the cage claw portion 21, stress concentration is likely to occur in the radially inner portion (the radially inner end of the pocket bottom surface 23) at the position corresponding to the middle of the circumferentially adjacent cage claw portions 21 in the cage ring portion 20. Therefore, as in the above embodiment, if a build-up portion 24 that bulges axially inward is formed at the radially inner end of the pocket bottom surface 23, it is possible to effectively prevent the cage ring portion 20 from being damaged due to stress concentration caused by centrifugal force.

[0082] Further, as shown in FIG. 4, this sealed ball bearing 1 has an outer diameter side oil groove 26 formed on the radially outer surface 25 of the cage claw portion 21 and an inner diameter side oil groove 28 formed on the radially inner surface 27 of the cage claw portion 21, so that the cross-sectional shape of the cage claw portion 21 becomes an H shape. Thus, while ensuring the second moment of inertia of the cross-section of the cage claw portion 21 (the resistance of the cage claw portion 21 to deformation against the bending moment), it is possible to suppress the mass of the cage claw portion 21. Therefore, when the bearing rotates at high speed, the torsional deformation of the cage ring portion 20 and the flexural deformation of the cage claw portion 21 itself caused by the centrifugal force received by the cage claw portion 21 can be suppressed to a small extent.

[0083] Further, as shown in FIG. 4, this sealed ball bearing 1 has the outer diameter side oil groove 26 formed such that the position of the groove bottom surface of the outer diameter side oil groove 26 gradually changes radially outward from the tip side to the root side of the cage claw portion 21. Therefore, when the bearing rotates, the lubricating oil in the outer diameter side oil groove 26 moves from the tip side to the root side of the cage claw portion 21 due to the pumping effect. Then, the lubricating oil that has moved through the outer diameter side oil groove 26 from the tip side to the root side of the cage claw portion 21 is returned axially inward by the rising surface 29 that rises radially outward from the root of the cage claw portion 21. By repeating this action, it is possible to efficiently circulate the lubricating oil in the bearing.

[0084] Further, as shown in Fig. 4, this sealed ball bearing 1 has an outer diameter side through groove 30 that axially penetrates the outer periphery of the cage ring portion 20 and an inner diameter side through groove 31 that axially penetrates the inner periphery of the cage ring portion 20. Therefore, lubricating oil can easily flow back and forth between the region axially inside the cage ring portion 20 and the region axially outside the cage ring portion 20 through the outer diameter side through groove 30 and the inner diameter side through groove 31, and it is possible to promote the circulation of the lubricating oil inside the bearing.

[0085] Further, as shown in Figs. 2 and 6, the outer diameter side through groove 30 and the inner diameter side through groove 31 are formed at the circumferential positions corresponding to the cage claw portions 21 in the cage ring portion 20 (that is, the positions where the rigidity is ensured by the cage claw portions 21 in the cage ring portion 20). Therefore, it is possible to effectively prevent the reduction in the rigidity of the cage ring portion 20 due to the formation of the outer diameter side through groove 30 and the inner diameter side through groove 31.

[0086] Further, as shown in Fig. 5, this sealed ball bearing 1 has an axial groove 32 formed on the outer periphery of the cage ring portion 20. Therefore, lubricating oil can easily flow back and forth between the region axially inside the cage ring portion 20 and the region axially outside the cage ring portion 20 through the axial groove 32, and it is possible to promote the circulation of the lubricating oil inside the bearing.

[0087] Further, as shown in Fig. 6, since the axial groove 32 is formed non - penetratingly on the axially inner side of the cage ring portion 20, it is possible to effectively prevent the breakage of the cage ring portion 20 due to stress concentration. That is, when the cage ring portion 20 is torsionally deformed by the centrifugal force acting on the cage claw portion 21, stress concentration is likely to occur on the axially inner side of the outer periphery of the cage ring portion 20. Therefore, by forming the axial groove 32 on the outer periphery of the cage ring portion 20 to be non - penetrating on the axially inner side, it is possible to effectively prevent the breakage of the cage ring portion 20 due to stress concentration.

[0088] Further, in this ball bearing 1 with a seal, since the axial length of the axial groove 32 shown in FIG. 5 is set to be 2 / 3 or less of the axial width of the cage ring portion 20, it is possible to effectively prevent a reduction in the rigidity of the cage ring portion 20 caused by forming the axial groove 32 on the outer periphery of the cage ring portion 20, and it is possible to effectively prevent breakage of the cage ring portion 20 due to stress concentration.

[0089] Further, as shown in FIG. 7(a), in this ball bearing 1 with a seal, the angle β formed by the cage-side inclined surface 40 and the seal-side inclined surface 39 formed radially inside the sliding contact portion between the cage-side sliding surface 35 and the seal-side sliding surface 34 is smaller than the angle γ formed by the chamfered portion 41 and the seal-side sliding surface 34 formed radially outside the sliding contact portion between the cage-side sliding surface 35 and the seal-side sliding surface 34. That is, the angle β formed between the cage 6 and the seal member 7 radially inside the sliding contact portion between the cage-side sliding surface 35 and the seal-side sliding surface 34 is smaller than the angle γ formed between the cage 6 and the seal member 7 radially outside the sliding contact portion between the cage-side sliding surface 35 and the seal-side sliding surface 34. Therefore, in the region axially sandwiched between the cage 6 and the seal member 7, a flow of lubricating oil occurs from radially inside the sliding contact portion between the cage-side inclined surface 40 and the seal-side inclined surface 39 toward radially outside the sliding contact portion between the cage-side inclined surface 40 and the seal-side inclined surface 39, and it is possible to efficiently lubricate the bearing.

[0090] In the above embodiment, the case where the axial projection 36 having the sliding contact tip surface 37 is formed on the seal-side sliding surface 34 and the sliding contact plane 38 with which the sliding contact tip surface 37 slides is formed on the cage-side sliding surface 35 has been described as an example. However, the configurations of the seal-side sliding surface 34 and the cage-side sliding surface 35 may be reversed. That is, an axial projection 36 having a sliding contact tip surface 37 may be formed on the cage-side sliding surface 35, and a sliding contact plane 38 with which the sliding contact tip surface 37 slides may be formed on the seal-side sliding surface 34.

[0091] In the above-described embodiment, the resin cage formed only of the resin composition was taken as an example for the cage 6. However, when molding the cage annular portion 20 and the cage claw portion 21 with the resin composition, it is also possible to adopt a resin cage in which an annular metal core bar is insert-molded in the portion of the cage annular portion 20. Further, it is also possible to adopt a mild steel cage in which the cage annular portion 20 and the cage claw portion 21 are integrally formed of mild steel.

[0092] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the scope of claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims are included.

Explanation of Reference Numerals

[0093] 1 Sealed ball bearing 2 Inner ring 3 Outer ring 4 Annular space 5 Ball 6 Cage 7 Seal member 20 Cage annular portion 21 Cage claw portion 22 Pocket side surface 23 Pocket bottom surface 24 Build-up portion 25 Radial outer surface 26 Outer diameter side oil groove 27 Radial inner surface 28 Inner diameter side oil groove 29 Upright surface 30 Outer diameter side through groove 31 Inner diameter side through groove 32 Axial groove 33 Notch 34 Seal side sliding surface 35 Cage side sliding surface 36 Axial projection 37 Contact tip surface 38 Contact plane 39 Seal side inclined surface 40 Cage side inclined surface 41 Chamfered portion 50 Transmission for Electric Vehicles 51 Electric Motor α, β, γ Angles L1, L2, L3 Straight Lines O Bearing Center

Claims

1. an inner ring (2), an outer ring (3) coaxially provided radially outside the inner ring (2), a plurality of balls (5) incorporated in an annular space (4) formed between the inner ring (2) and the outer ring (3), an annular seal member (7) provided at one axial end opening of the annular space (4), a cage (6) for holding the plurality of balls (5), and in the ball bearing with a seal, the cage (6) has a cage annular portion (20) extending in the circumferential direction in a region axially sandwiched between a passage region of the ball (5) and the seal member (7), and a cantilevered cage claw portion (21) extending in the axial direction between the balls (5) adjacent in the circumferential direction from the cage annular portion (20), the seal member (7) has a seal-side sliding surface (34) axially opposed to the cage (6), the cage (6) has a cage-side sliding surface (35) axially opposed to the seal-side sliding surface (34), a plurality of axial protrusions (36) are formed at intervals in the circumferential direction on one of the seal-side sliding surface (34) and the cage-side sliding surface (35), each axial protrusion (36) has a sliding contact tip surface (37) linearly extending in the radial direction in a cross-sectional view perpendicular to the circumferential direction, a smooth sliding contact plane (38) is formed over the entire circumference on the other sliding surface in sliding contact with the sliding contact tip surface (37) during rotation of the bearing, the ball bearing with a seal, characterized in that the sliding contact tip surface (37) and the sliding contact plane (38) are arranged non-parallel to each other with an angle (α) in a direction in which the distance increases from the radially inner side to the radially outer side when the bearing is stationary.

2. The ball bearing with a seal according to claim 1, wherein an angle (α) formed between the sliding contact tip surface (37) and the sliding contact plane (38) when the bearing is stationary is set in a range of 0.5° or more and 6° or less.

3. the axial length of the cage claw portion (21) is set to be larger than the radius of the ball (5), the cage claw portion (21) has a pocket side surface (22) facing the ball (5) in the circumferential direction, The ball bearing with a seal according to claim 1 or 2, wherein a portion of the pocket side surface (22) for receiving the ball (5) in the circumferential direction has a planar shape so that the pocket side surface (22) does not interfere with the ball (5) when the cage claw portion (21) moves radially outward by centrifugal force.

4. The pocket side surface (22) is a plane along a straight line (L １ ) extending radially through the bearing center (O). The sealed ball bearing according to claim 3.

5. The pocket side surface (22) is a plane along a straight line (L ２ ) that sandwiches a straight line (L ３ ) parallel to and circumferentially opposed to the straight line connecting the bearing center (O) and the circumferential center of the cage claw portion (21). The sealed ball bearing according to claim 3.

6. The retainer ring portion (20) has a pocket bottom surface (23) that faces the ball (5) in the axial direction. The pocket bottom surface (23) has a shape that extends linearly in the radial direction in a cross-sectional view perpendicular to the circumferential direction. The sealed ball bearing according to any one of claims 3 to 5, wherein the pocket side surface (22) and the pocket bottom surface (23) are connected in a concave arc shape when viewed from the radial direction.

7. The sealed ball bearing according to claim 6, wherein a build-up portion (24) that bulges axially inward without contacting the ball (5) is formed at the radially inner end of the pocket bottom surface (23).

8. An outer diameter side oil groove (26) that extends axially from the tip of the retainer claw portion (21) toward the retainer ring portion (20) is formed on the radially outer surface (25) of the retainer claw portion (21). An inner diameter side oil groove (28) that extends axially from the tip of the retainer claw portion (21) toward the retainer ring portion (20) is formed on the radially inner surface (27) of the retainer claw portion (21). The sealed ball bearing according to any one of claims 1 to 7, wherein the retainer claw portion (21) has an H-shaped cross-sectional shape perpendicular to the axial direction that is open to the radially outer side and the radially inner side by the outer diameter side oil groove (26) and the inner diameter side oil groove (28).

9. The outer diameter side oil groove (26) is formed such that the position of the groove bottom surface of the outer diameter side oil groove (26) gradually changes radially outward from the tip side to the root side of the retainer claw portion (21). The sealed ball bearing according to claim 8, wherein a planar rising surface (29) that rises radially outward from the root of the retainer claw portion (21) is formed on the retainer ring portion (20).

10. The sealed ball bearing according to any one of claims 1 to 9, wherein an outer diameter side through groove (30) that penetrates the outer periphery of the retainer ring portion (20) in the axial direction is formed at a circumferential position corresponding to the retainer claw portion (21).

11. An axial groove (32) that extends axially along the outer periphery of the retainer ring portion (20) between the outer diameter side through grooves (30) adjacent to each other in the circumferential direction, is open to the axially outer side of the retainer ring portion (20), and is non-through to the axially inner side of the retainer ring portion (20) is formed.

12. The sealed ball bearing according to claim 11, wherein the axial length of the axial groove (32) is set to 2 / 3 or less of the axial width of the retainer ring portion (20).

13. The sealed ball bearing according to any one of claims 1 to 12, wherein an inner diameter side through groove (31) penetrating the inner circumference of the retainer ring portion (20) in the axial direction is formed at a circumferential position corresponding to the retainer claw portion (21).

14. The seal member (7) has a seal side inclined surface (39) extending linearly and inclined axially inward from the seal side sliding surface (34) toward the radially inner side in a cross-sectional view perpendicular to the circumferential direction. The retainer ring portion (20) has a retainer side inclined surface (40) extending linearly and inclined axially inward from the retainer side sliding surface (35) toward the radially inner side in a cross-sectional view perpendicular to the circumferential direction, and a chamfered portion (41) extending linearly and inclined axially inward from the retainer side sliding surface (35) toward the radially outer side. An angle (β) formed by the retainer side inclined surface (40) and the seal side inclined surface (39) is set to 10° or less. The sealed ball bearing according to any one of claims 1 to 13, wherein an angle (γ) formed by the chamfered portion (41) and the seal side sliding surface (34) is set to be greater than 10° and 48° or less.

15. The sealed ball bearing according to claim 8 or 9, wherein notches (33) penetrating the groove shoulders on both circumferential sides of the outer diameter side oil groove (26) and the inner diameter side oil groove (28) are formed at the tips of the retainer claw portions (21).

16. The sealed ball bearing according to any one of claims 1 to 15, wherein the retainer (6) is a resin retainer.

17. The sealed ball bearing according to any one of claims 1 to 16, which is used as a bearing for an electric motor (51) of an electric vehicle or a bearing for an electric vehicle transmission (50) that decelerates the rotation of the electric motor (51).

Images