Grease-packed ball bearings

Abstract

To provide a grease enclosed ball bearing which can prevent grease leakage effectively.SOLUTION: In a grease enclosed ball bearing, a retainer claw part 15 has: a pocket surface 21 facing a surface of a ball 4; and a claw inner diameter surface 23 which extends from a radial inner edge 22 of the pocket surface 21 in a circumferential direction so as to face an outer periphery of an inner ring 1. The claw inner diameter surface 23 is provided with an inclination for grease guide which is displaced from the root side of the retainer claw part 15 to the tip side of the retainer claw part 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a grease-filled ball bearing in which grease is filled in an annular bearing space formed between an inner ring and an outer ring. [Background technology]

[0002] Grease-filled ball bearings, in which grease is filled in an annular bearing space formed between an inner ring and an outer ring, are known as bearings for supporting rotating shafts in automobiles, industrial machinery, and the like (for example, Patent Documents 1 to 3).

[0003] The grease-sealed ball bearings in Patent Documents 1 to 3 include an inner ring, an outer ring coaxially disposed radially outward of the inner ring, multiple balls mounted in a bearing space between the inner and outer rings, annular seal members disposed at both axial ends of the bearing space, grease sealed in the bearing space, and a cage that holds the multiple balls. The cage is a so-called crown cage that has a cage annular portion extending circumferentially and cantilever-shaped cage claws that extend axially from the cage annular portion between circumferentially adjacent balls. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6940993 [Patent Document 2] Japanese Patent Application Publication No. 2020-128786 [Patent Document 3] Japanese Patent Application Publication No. 2019-2498 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 increase the speed of electric motors in order to reduce their size and weight. 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 grease-packed ball bearings as bearings that support a rotating shaft that rotates at high speed, such as a rotating shaft that receives rotation from an electric motor in an electric vehicle. When a rotating shaft that rotates at high speed is supported by a grease-packed ball bearing, it is necessary to extend the life of the grease in order to ensure the life of the bearing.

[0007] In other words, the lifespan of a greased ball bearing is usually shorter than the lifespan of the bearing (fatigue life) where abnormalities occur due to fatigue of the bearing components. Therefore, when considering the lifespan of a greased ball bearing, the grease life is the dominant factor. Furthermore, when a bearing is used in a high-speed rotation application, the total number of rotations of the bearing increases compared to when it is used in a low-speed rotation application, even if the operating time is the same.

[0008] Therefore, when grease-sealed ball bearings are used as bearings to support a rotating shaft that rotates at high speeds, it is necessary to extend the life of the grease (i.e., to increase the total number of rotations of the bearing until the grease life is reached).

[0009] One way to extend the life of the grease is to increase the amount of grease sealed in the bearing space. However, simply increasing the amount of grease sealed in only makes the grease more likely to leak. As a result, the amount of grease that can actually be used cannot be increased, and the life of the grease is not extended.

[0010] The present inventors therefore investigated the mechanism by which grease leakage occurs when the amount of grease sealed in the bearing space is increased. As a result, the present inventors discovered the following grease leakage mechanism: in a grease-sealed ball bearing, as the bearing rotates, grease from the surfaces of the balls is scraped off by the cage claws and accumulates on the inner diameter surfaces of the cage claws; as the amount of grease accumulating on the inner diameter surfaces of the cage claws increases, some of the grease moves to the inner diameter surface of the cage annular portion; as the amount of grease accumulating on the inner diameter surface of the cage annular portion increases further, the grease that overflows from the inner diameter surface of the cage annular portion reaches the contacting or non-contacting seal portion between the seal member and the inner ring, and the grease that reaches this seal portion gradually leaks out of the bearing.

[0011] The inventors of the present application then came up with the idea that if, when grease on the surface of the ball is scraped off by the retainer claw portion and accumulates on the inner diameter surface of the retainer claw portion, the grease accumulated on the inner diameter surface of the retainer claw portion can be prevented from moving to the inner diameter surface of the retainer ring portion, it will be possible to prevent grease leakage even when the amount of grease sealed in the bearing space is increased.

[0012] The problem to be solved by the present invention is to provide a grease-sealed ball bearing that can effectively prevent grease leakage. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides a grease-sealed ball bearing having the following configuration. With inner circle, an outer ring provided coaxially on the radially outer side of the inner ring; a plurality of balls installed in an annular bearing space formed between the inner ring and the outer ring; an annular seal member provided at one axial end of the bearing space; Grease sealed in the bearing space; a cage that holds the plurality of balls, the cage has a cage annular portion extending in a circumferential direction and cantilever-shaped cage claw portions extending in an axial direction from the cage annular portion between the balls adjacent in the circumferential direction, In a grease-sealed ball bearing, the cage claw portion has a pocket surface facing the surface of the ball, and a claw inner diameter surface extending circumferentially from a radially inner edge of the pocket surface so as to face an outer periphery of the inner ring, A grease-sealed ball bearing, characterized in that the inner diameter surface of the claw is provided with a slope for guiding grease that displaces radially outward from the base side of the retainer claw portion toward the tip side of the retainer claw portion.

[0014] In this way, the grease guide slopes on the inner diameter surfaces of the claws and the centrifugal force acting on the grease can prevent the grease that has accumulated on the inner diameter surfaces of the claws from moving to the inner diameter surface of the cage annular portion. As a result, the grease that has been scraped off the surfaces of the balls by the cage claws and accumulated on the inner diameter surfaces of the claws is prevented from reaching the seal member, making it possible to effectively prevent grease leakage.

[0015] the retainer annular portion has, in a cross section passing through the center of the ball and perpendicular to the circumferential direction, a pocket bottom portion that faces the ball in the axial direction, and an annular portion inner diameter surface that extends in the axial direction from a radial inner end of the pocket bottom portion and faces the outer periphery of the inner ring in the radial direction, It is preferable to adopt a configuration in which the inclination of the claw inner diameter surface is set such that the position where the pocket bottom and the annular portion inner diameter surface intersect is set as the inclination start position.

[0016] With this configuration, the claw inner diameter surface is inclined with the inclination start position being the position where the pocket bottom and the annular portion inner diameter surface intersect (i.e., the position of the root end of the cage claw), which makes it possible to particularly effectively prevent grease scraped off the surface of the ball by the cage claw from moving to the annular portion inner diameter surface. In other words, as the bearing rotates, grease adhering to the inner circumference of the outer ring and the outer circumference of the inner ring is pushed aside to both sides in the axial direction by the balls, so that the amount of grease adhering to the surface of the ball is greater at areas on both sides of the axial direction than at areas in contact with the axial centers of the outer ring raceway surface and the inner ring raceway surface, and the amount of grease scraped off the surface of the ball by the cage claw is usually greatest at the root end of the cage claw. Therefore, by inclining the inner diameter surface of the claw with the root end of the retainer claw as the starting position for inclination, the inner diameter surface of the claw will have a slope for guiding grease at the position where the amount of grease scraped off by the retainer claw is the greatest, making it possible to particularly effectively prevent the grease scraped off from the surface of the ball by the retainer claw from moving to the inner diameter surface of the annular portion.

[0017] It is preferable to employ a configuration in which the entire radially inner surface of the cage claw portion is disposed radially outward of the inner diameter surface of the annular portion.

[0018] In this way, even if grease accumulates anywhere on the radially inner surface of the cage claws, in order for the grease to move to the inner diameter surface of the annular portion, the grease must move radially inward against the centrifugal force acting on it, so it is possible to effectively prevent grease that has accumulated on the radially inner surface of the cage claws from migrating to the inner diameter surface of the annular portion. Furthermore, if the entire radially inner surface of the cage claws is positioned radially outward from the inner diameter surface of the annular portion, the volume of the cage claws can be kept small, which makes it possible to increase the amount of grease that can be sealed in the bearing space.

[0019] It is preferable that the retainer annular portion further has a seal opposing surface that faces the seal member in the axial direction, and a tapered surface for grease escape that connects the seal opposing surface and the inner diameter surface of the annular portion at an angle.

[0020] In this way, the inner diameter surface of the retainer annular portion and the seal opposing surface do not intersect directly, but are connected via an inclined grease escape tapered surface.Therefore, even if grease accumulates on the inner diameter surface of the annular portion and moves axially along the inner diameter surface of the annular portion toward the seal member, the centrifugal force acting on the grease will cause the grease to move radially outward along the grease escape tapered surface, preventing the grease from reaching the seal portion between the seal member and the inner ring.

[0021] the retainer annular portion has an outer diameter surface that faces the inner periphery of the outer ring in the radial direction, It is preferable to employ a configuration in which the radial gap between the outer periphery of the inner ring and the inner diameter surface of the annular portion is set larger than the radial gap between the inner periphery of the outer ring and the outer diameter surface of the annular portion.

[0022] In this way, the radial gap between the outer periphery of the inner ring and the inner diameter surface of the annular portion is large, so that even if grease accumulates on the inner diameter surface of the annular portion and moves axially along the inner diameter surface of the annular portion toward the sealing member, the grease can be prevented from reaching the sealing portion between the sealing member and the inner ring.

[0023] It is preferable to adopt a configuration in which a grease receiving recess is formed on the inner diameter surface of the annular portion, extending axially through the intermediate positions of the balls adjacent in the circumferential direction.

[0024] In this way, even if grease adheres to the inner diameter surface of the annular portion, the grease can be introduced into the grease accommodating recess, preventing the grease from reaching the sealing portion between the sealing member and the inner ring.

[0025] It is preferable to adopt a configuration in which the retainer claw portion is formed with a grease passage groove that extends radially through the intermediate position between adjacent balls in the circumferential direction, with a depth that extends axially from the tip of the retainer claw portion to the base of the retainer claw portion beyond the pitch circle connecting the centers of the plurality of balls.

[0026] With this configuration, as the bearing rotates, grease from the surfaces of the balls is scraped off by the cage claws and accumulates on the claw inner diameter surfaces. When the grease overflows from the claw inner diameter surfaces, it passes through the grease passage grooves and moves radially outward by centrifugal force, allowing the grease inside the bearing to circulate without passing near the seal member, effectively preventing the grease circulating inside the bearing from reaching the seal portion between the seal member and the inner ring. Furthermore, because the volume of the cage claws can be reduced by the amount of the grease passage grooves, it is also possible to increase the amount of grease that can be sealed in the bearing space.

[0027] The axial length of the cage claw portion is set to be longer than the radius of the ball, It is preferable to adopt a configuration in which the inner diameter of the claw inner diameter surface is set to be smaller than the pitch circle so that the radially inner edge of the pocket surface is located radially inward of the pitch circle connecting the centers of the multiple balls.

[0028] In this way, the balls are held stably by the cage claws.

[0029] It is preferable to adopt a configuration in which a chamfer of 0.5 mm or more is provided at the edge where the pocket surface and the claw inner diameter surface intersect.

[0030] This makes it possible to prevent the claws of the cage from scraping off grease from the surface of the balls, and also makes it possible to effectively lubricate the surface of the balls with the grease that accumulates in the chamfers.

[0031] It is preferable to employ a configuration in which a grease groove is formed in the cage claw portion so as to extend across the pocket surface in the radial direction.

[0032] In this way, the grease accumulated in the grease grooves and the grease accumulated on the inner diameter surfaces of the claws can effectively lubricate the surfaces of the balls.

[0033] The cage may be formed from a resin composition in which a fiber reinforcement material is added to a resin material.

[0034] The amount of grease to be filled is preferably set to 38% or more of the total space volume, which is the volume of the bearing space minus the volume of the cage and the volume of the plurality of balls.

[0035] This allows for a larger amount of grease to be packed into the bearing than in a normal grease-sealed ball bearing, and grease leakage is less likely to occur, so the life of the bearing (grease life) can be extended, which would otherwise cause poor lubrication due to grease deterioration.

[0036] The amount of grease to be filled is preferably set to 100% or more of the static space volume, which is the volume obtained by subtracting the volume of the area through which the cage and the plurality of balls pass when the bearing rotates from the volume of the bearing space.

[0037] This allows a larger amount of grease to be packed in than in a normal grease-packed ball bearing, and also makes it less likely for grease to leak, thereby extending the life of the grease. [Effects of the Invention]

[0038] In the grease-sealed ball bearing of this invention, the grease-guiding slopes on the inner diameter surfaces of the claws and the centrifugal force acting on the grease prevent grease that has accumulated on the inner diameter surfaces of the claws from migrating to the inner diameter surface of the cage annular portion. As a result, grease that has been scraped off the surfaces of the balls by the cage claws and accumulated on the inner diameter surfaces of the claws is prevented from reaching the seal member, making it possible to effectively prevent grease leakage. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 is a cross-sectional view showing a grease-sealed ball bearing according to a first embodiment of the present invention. [Figure 2] An enlarged cross-sectional view of the cage and its surroundings in FIG. [Figure 3]A cross-sectional view of the grease-packed ball bearing in Figure 2, taken along a plane perpendicular to the axial direction and passing through the center of the ball [Figure 4] Right side view of the cage shown in Figure 2 [Figure 5] Cross-sectional view along line VV in Figure 4 [Figure 6] FIG. 2 is a perspective view of the cage of FIG. 1 as seen from the cage claw portion side. [Figure 7] An enlarged perspective view of the cage showing the state of grease accumulated on the inner diameter surfaces of the claws when the amount of grease packed in the grease-packed ball bearing of Figure 1 is reduced. [Figure 8] An enlarged perspective view of the cage showing the state of grease accumulated on the inner diameter surfaces of the claws of the grease-packed ball bearing in Figure 1. [Figure 9] FIG. 5 is a diagram showing a second embodiment of the present invention, corresponding to FIG. 4. [Figure 10] Cross-sectional view along line XX in Figure 9 [Figure 11] FIG. 10 is an enlarged perspective view of the cage shown in FIG. 9 as seen from the radially inner side. [Figure 12] FIG. 10 is a perspective view of a cage of a grease-sealed ball bearing according to a third embodiment of the present invention, as viewed from the radially inner side. [Figure 13] FIG. 13 is an enlarged perspective view of a cage showing a modified example in which a grease receiving recess is provided in the cage shown in FIG. 12; [Figure 14] FIG. 10 is a perspective view of a cage of a grease-sealed ball bearing according to a fourth embodiment of the present invention, viewed from the radially inner side; [Figure 15] FIG. 10 is a cross-sectional view of a cage of a grease-sealed ball bearing according to a fifth embodiment of the present invention, taken along a plane perpendicular to the axial direction and passing through the center of the ball. [Figure 16] FIG. 2 is a cross-sectional view showing a grease-sealed ball bearing of a comparative example, corresponding to FIG. 1. [Figure 17] FIG. 17 is an enlarged cross-sectional view showing the vicinity of the cage in FIG. 16. [Figure 18] A cross-sectional view of the grease-packed ball bearing in Figure 17, taken along a plane perpendicular to the axial direction and passing through the center of the ball [Figure 19] An enlarged perspective view of the cage showing the state of grease accumulated on the inner diameter surfaces of the claws of the grease-packed ball bearing of Figure 16. [Figure 20]An enlarged perspective view of the cage showing the state of grease accumulated on the inner diameter surface of the claws when the amount of grease packed in the grease-packed ball bearing of Figure 16 is increased. [Figure 21] This figure shows the results of an analysis of the radial displacement caused by the deflection of the cage claws when the grease-sealed ball bearing in Figure 16 is rotated at high speed. [Figure 22] This figure shows the results of an analysis of the radial displacement caused by the deflection of the cage claws when the grease-sealed ball bearing in Figure 1 is rotated at high speed. DETAILED DESCRIPTION OF THE INVENTION

[0040] Figure 1 shows a greased ball bearing according to a first embodiment of the present invention. This greased ball bearing comprises an inner ring 1, an outer ring 2 disposed coaxially radially outward of the inner ring 1, a plurality of balls 4 mounted at intervals in the circumferential direction in an annular bearing space 3 formed between the inner ring 1 and the outer ring 2, an annular seal member 5 disposed at one of the axial ends of the bearing space 3 (the left end in the figure), an annular seal member 6 disposed at the other axial end of the bearing space 3 (the right end in the figure), and a cage 7 that maintains the circumferential spacing of the plurality of balls 4.

[0041] The inner circumference of the outer ring 2 is formed with an outer ring raceway groove 8 with which the balls 4 roll, a pair of outer ring groove shoulders 9 located axially outward of the outer ring raceway groove 8, and a pair of seal fixing grooves 10 located axially outward of the outer ring groove shoulders 9. The outer ring raceway groove 8 is formed extending circumferentially through the axial center of the inner circumference of the outer ring 2. The pair of outer ring groove shoulders 9 are bank-shaped portions extending circumferentially on both sides of the outer ring raceway groove 8 in the axial direction. The seal fixing groove 10 is a groove extending circumferentially formed adjacent to the axial outside of the outer ring groove shoulders 9. Seal members 5, 6 are fitted into and fixed in the pair of seal fixing grooves 10, respectively.

[0042] The outer periphery of the inner ring 1 is formed with an inner ring raceway groove 11 with which the balls 4 roll, a pair of inner ring groove shoulders 12 located axially outward of the inner ring raceway groove 11, and a pair of sliding recesses 13 located axially outward of the inner ring groove shoulders 12. The inner ring raceway groove 11 is formed extending circumferentially through the axial center of the outer periphery of the inner ring 1. The pair of inner ring groove shoulders 12 are bank-shaped portions extending circumferentially on both sides of the inner ring raceway groove 11 in the axial direction. The sliding recesses 13 are recesses extending circumferentially and formed adjacent to the axial outside of the inner ring groove shoulders 12. Seal lips formed on the inner peripheries of the seal members 5, 6 are in sliding contact with the pair of sliding recesses 13, respectively.

[0043] Here, a contact-type seal member in which the seal lip on the inner periphery of the seal members 5, 6 is brought into sliding contact with the sliding recess 13 has been taken as an example, but a non-contact-type seal member in which a labyrinth gap is formed between the seal lip on the inner periphery of the seal members 5, 6 and the sliding recess 13 may also be used as the seal members 5, 6. The labyrinth gap is a minute gap that can prevent the intrusion of foreign matter, and is, for example, a gap with a width dimension set to 0.5 mm or less.

[0044] The balls 4 are sandwiched radially between the outer ring raceway groove 8 and the inner ring raceway groove 11. This sealed ball bearing is a deep groove ball bearing. That is, the outer ring raceway groove 8 is an arc groove with an axially symmetric concave arc cross section, and the inner ring raceway groove 11 is also an arc groove with an axially symmetric concave arc cross section. The arc radius of the cross section of the outer ring raceway groove 8 is slightly larger than the radius of the balls 4. The arc radius of the cross section of the inner ring raceway groove 11 is also slightly larger than the radius of the balls 4.

[0045] The cage 7 is a so-called crown cage having a cage annular portion 14 that extends circumferentially through the area axially sandwiched between the ball 4 passage area and the seal member 5, and cage claw portions 15 that extend axially from the cage annular portion 14 between circumferentially adjacent balls 4. The cage annular portion 14 and the cage claw portions 15 are formed seamlessly and integrally from a resin composition in which a fiber reinforcement material is added to a resin material.

[0046] Polyamide (PA) or super engineering plastics can be used as the base resin material for the resin composition. Examples of polyamides that can be used include polyamide 46 (PA46), polyamide 66 (PA66), and polynonamethylene terephthalamide (PA9T). Examples of super engineering plastics that can be used include polyether ether ketone (PEEK) and polyphenylene sulfide (PPS). Examples of fiber reinforcements that can be added to the resin material include glass fiber, carbon fiber, and aramid fiber.

[0047] As shown in Figure 5, in a cross section perpendicular to the circumferential direction passing through the center of the ball 4, the retainer annular portion 14 has a pocket bottom 16 that faces the ball 4 in the axial direction, an annular portion outer diameter surface 17 that extends in the axial direction from the radial outer end of the pocket bottom 16, an annular portion inner diameter surface 18 that extends in the axial direction from the radial inner end of the pocket bottom 16, a seal opposing surface 19 that faces the seal member 5 (see Figure 1) in the axial direction, and a grease escape tapered surface 20 that connects the seal opposing surface 19 and the annular portion inner diameter surface 18 at an angle.

[0048] As shown in Figure 2, the annular portion outer diameter surface 17 is a cylindrical outer diameter surface extending circumferentially at a position radially opposed to the outer ring groove shoulder 9 on the inner circumference of the outer ring 2. The annular portion inner diameter surface 18 is a cylindrical inner diameter surface extending circumferentially at a position radially opposed to the inner ring groove shoulder 12 on the outer circumference of the inner ring 1. The seal-opposing surface 19 is an annular surface perpendicular to the axial direction that extends circumferentially at a position axially opposed to the seal member 5. The radial gap between the outer circumference of the inner ring 1 and the annular portion inner diameter surface 18 is set larger than the radial gap between the inner circumference of the outer ring 2 and the annular portion outer diameter surface 17.

[0049] 5, the cage claw portion 15 is formed in a cantilever shape with one axial end being a fixed end (the base of the cage claw portion 15) fixed to the cage annular portion 14 and the other axial end being a free end (the tip of the cage claw portion 15). The axial length of the cage claw portion 15 is set longer than the radius of the balls 4 so that the cage claw portion 15 extends farther from the cage annular portion 14 than the pitch circle P connecting the centers of the multiple balls 4.

[0050] As shown in Figures 4 and 5, the cage claw portion 15 has a pocket surface 21 that faces the surface of the ball 4 in the circumferential direction, a claw inner diameter surface 23 that extends circumferentially from a radially inner edge 22 of the pocket surface 21, and a claw outer diameter surface 24 that extends circumferentially from a radially outer edge of the pocket surface 21. The pocket surface 21 is formed in a concave spherical shape that follows the surface of the ball 4. As shown in Figure 5, the end of the pocket surface 21 on the side of the cage annular portion 14 is connected to the pocket bottom 16 of the cage annular portion 14. As shown in Figure 2, the claw inner diameter surface 23 faces radially the inner ring raceway groove 11 and inner ring groove shoulder 12 on the outer periphery of the inner ring 1.

[0051] 5, the claw inner diameter surface 23 is composed of an inclined inner diameter surface 23a formed at the end on the root side of the cage claw portion 15, and a non-inclined inner diameter surface 23b that continues from the inclined inner diameter surface 23a to the tip side of the cage claw portion 15. The inclined inner diameter surface 23a is inclined so as to displace radially outward from the root side of the cage claw portion 15 (the side closer to the cage annular portion 14) toward the tip side of the cage claw portion 15 (the side farther from the cage annular portion 14). The inclined inner diameter surface 23a can also be a conical surface with a constant degree of inclination along the axial direction, but here a funnel-shaped surface is used in which the degree of inclination gradually increases as it approaches the cage annular portion 14 along the axial direction.

[0052] The inclination of the inclined inner diameter surface 23a is set such that the inclination start position is the position C where the pocket bottom 16 and the annular portion inner diameter surface 18 intersect, so that the entire radially inner surface of the cage claw portion 15 is positioned radially outward of the annular portion inner diameter surface 18. The non-inclined inner diameter surface 23b is a constant cylindrical surface or plane whose radial position does not change along the axial direction. The inclined inner diameter surface 23a and the non-inclined inner diameter surface 23b are connected along the axial direction on the side closer to the cage annular portion 14 than the position of the pitch circle P. The inner diameter of the claw inner diameter surface 23 (the inner diameter of the non-inclined inner diameter surface 23b in the figure) is set smaller than the pitch circle P so that the radially inner edge 22 of the pocket surface 21 is positioned radially inward of the pitch circle P.

[0053] The outer diameter of the claw outer diameter surface 24 is set to be larger than the pitch circle P.

[0054] 3 and 6, the cage claw portion 15 is formed with a grease passage groove 25 that extends radially through the middle position between circumferentially adjacent balls 4. As shown in Fig. 2, the grease passage groove 25 has a depth that extends axially from the tip of the cage claw portion 15 to the root side of the cage claw portion 15 beyond the pitch circle P (see Fig. 5).

[0055] Grease is sealed in the annular bearing space 3 defined by the inner ring 1, outer ring 2, and seal members 5, 6 on both axial sides, as shown in Figure 1. Grease is a lubricant containing a base oil such as synthetic oil (synthetic hydrocarbon) or mineral oil (refined from petroleum), and a thickener that disperses in the base oil to make it semi-solid. The base oil is a lubricant containing 45 to 50 mm 2 It is preferable to use a base oil having a kinematic viscosity of 50mm / s. 2 By setting the kinematic viscosity of the base oil at 45mm / s or less, the grease becomes softer and the rotational torque of the ball bearing can be effectively reduced. 2 By setting the rotational speed at or above 1 / s, scattering of grease inside the bearing during high-speed rotation can be suppressed, and grease leakage from the bearing can be effectively reduced.

[0056] In the grease-sealed ball bearing of this embodiment, the amount of grease sealed is set to 38% or more of the total space volume, which is the volume of the bearing space 3 minus the volume of the cage 7 and the volume of the multiple balls 4. In addition, the amount of grease sealed is set to 100% or more of the static space volume, which is the volume of the bearing space 3 minus the volume of the area through which the cage 7 and multiple balls 4 pass when the bearing is rotating.

[0057] As shown in Figures 2 and 5, the grease-sealed ball bearing of this embodiment has a grease guide slope on the claw inner diameter surface 23 that displaces radially outward from the base side of the retainer claw portion 15 toward the tip side of the retainer claw portion 15, making it possible to effectively prevent grease leakage even when a large amount of grease is sealed in the bearing space 3.

[0058] 16 to 18, a comparative example is assumed in which the claw inner diameter surface 23 is not inclined and the radial position of the claw inner diameter surface 23 is constant and does not change along the axial direction. In this case, as the bearing rotates, grease on the surfaces of the balls 4 is scraped off by the cage claw portions 15 and accumulates on the claw inner diameter surface 23 and the claw outer diameter surface 24, as shown in Fig. 18. In a typical grease-sealed ball bearing, the amount of grease sealed in the bearing space 3 is relatively small, so the grease scraped off by the cage claw portions 15 remains in that position and does not normally move to the annular portion inner diameter surface 18, as shown in Fig. 19. However, if the amount of grease sealed in the bearing space 3 is increased, as shown in Fig. 17, more grease will be scraped off by the cage claws 15 and accumulate on the claw inner diameter surfaces 23, some of this grease will move to the annular portion inner diameter surface 18, and as more grease accumulates on the annular portion inner diameter surface 18, the grease that overflows from the annular portion inner diameter surface 18 will reach the seal portion between the seal member 5 and the inner ring 1 (the sliding contact portion between the seal lip on the inner circumference of the seal member 5 and the sliding recess 13 on the outer circumference of the inner ring 1), and the grease that has reached this seal portion may gradually leak out of the bearing. In this case, if the grease that has accumulated on the annular portion inner diameter surface 18 comes into contact with the inner ring groove shoulder 12 as shown in Fig. 17, the grease will adhere to the entire annular portion inner diameter surface 18, as shown in Fig. 20.

[0059] In contrast, the grease-sealed ball bearing of the above embodiment has grease guiding slopes on the claw inner diameter surface 23 that displace radially outward from the base side of the cage claw portions 15 toward the tip side of the cage claw portions 15, as shown in Figures 2 and 5. Therefore, as the bearing rotates, when grease is scraped off the surfaces of the balls 4 by the cage claw portions 15 and accumulates on the claw inner diameter surface 23 as shown in Figure 3, the grease that has accumulated on the claw inner diameter surface 23 is subjected to a force from the base side of the cage claw portions 15 toward the tip side of the cage claw portions 15 due to the grease guiding slopes on the claw inner diameter surface 23 and the centrifugal force acting on the grease, as shown in Figure 2. This prevents the grease scraped off the surfaces of the balls 4 by the cage claw portions 15 and accumulated on the claw inner diameter surface 23 from moving to the annular portion inner diameter surface 18 and reaching the seal member 5, effectively preventing grease leakage. At this time, the grease accumulated on the claw inner diameter surface 23 is blocked by the inclined inner diameter surface 23a of the claw inner diameter surface 23, as shown in Fig. 8. Fig. 7 is a diagram showing the state of grease scraped off by the cage claw portion 15 and accumulated on the claw inner diameter surface 23 when the amount of grease packed in the grease-packed ball bearing of the above embodiment is reduced.

[0060] Furthermore, as shown in Figure 5, in the grease-sealed ball bearing of this embodiment, the claw inner diameter surface 23 is inclined from the position C where the pocket bottom 16 and the annular portion inner diameter surface 18 intersect (i.e., the position of the root end of the retainer claw portion 15) as the inclination starting position, so that it is possible to particularly effectively prevent grease scraped off the surface of the ball 4 by the retainer claw portion 15 from migrating to the annular portion inner diameter surface 18.

[0061] 2 is scraped away to both axial sides by ball 4, the amount of grease adhering to the surface of ball 4 is greater at both axial sides of outer ring raceway groove 8 and inner ring raceway groove 11 than at the axial center of outer ring raceway groove 8 and inner ring raceway groove 11, and the amount of grease scraped off from the surface of ball 4 by cage claw portion 15 is usually greatest at the root end of cage claw portion 15. Therefore, as shown in FIG. 5, if claw inner diameter surface 23 is tilted with position C at the root end of cage claw portion 15 as the tilt start position, claw inner diameter surface 23 will have a grease guide slope at the position where the amount of grease scraped off by cage claw portion 15 is greatest, and this makes it possible to particularly effectively prevent grease scraped off from the surface of ball 4 by cage claw portion 15 from moving to annular portion inner diameter surface 18.

[0062] 2 and 5, in the grease-sealed ball bearing of this embodiment, the entire radially inner surface of the cage claw portions 15 is positioned radially outward of the annular portion inner diameter surface 18. Therefore, even if grease accumulates anywhere on the radially inner surface of the cage claw portions 15, in order for the grease to move to the annular portion inner diameter surface 18, the grease must move radially inward against the centrifugal force acting on the grease, making it possible to effectively prevent grease that has accumulated on the radially inner surface of the cage claw portions 15 from moving to the annular portion inner diameter surface 18.

[0063] Furthermore, in the grease-sealed ball bearing of this embodiment, as shown in Figure 2, the entire radially inner surface of the retainer claw portion 15 is positioned radially outward from the inner diameter surface 18 of the annular portion.Therefore, as shown in Figure 17, compared to the comparative example in which the radially inner surface of the retainer claw portion 15 is positioned at the same radial position as the inner diameter surface 18 of the annular portion, it is possible to keep the volume of the retainer claw portion 15 small, and as a result, it is possible to increase the amount of grease sealed in the bearing space 3.

[0064] Furthermore, as shown in Figure 2, in the grease-sealed ball bearing of this embodiment, the annular portion inner diameter surface 18 of the retainer annular portion 14 and the seal opposing surface 19 are not directly intersected, but are connected via an oblique grease escape tapered surface 20. Therefore, even if grease accumulates on the annular portion inner diameter surface 18 and moves axially along the annular portion inner diameter surface 18 toward the seal member 5, the centrifugal force acting on the grease will cause the grease to move radially outward along the grease escape tapered surface 20, making it possible to prevent the grease from reaching the seal portion between the seal member 5 and the inner ring 1.

[0065] Furthermore, as shown in Figure 2, the grease-sealed ball bearing of this embodiment has a large radial gap between the outer periphery of the inner ring 1 and the inner diameter surface 18 of the annular portion. Therefore, even if grease accumulates on the inner diameter surface 18 of the annular portion and moves axially along the inner diameter surface 18 toward the sealing member 5, the grease can be prevented from reaching the sealing portion between the sealing member 5 and the inner ring 1.

[0066] 2 and 3, the grease-sealed ball bearing of this embodiment has grease passing grooves 25 that extend radially through the cage claws 15, so that when grease on the surfaces of the balls 4 is scraped off by the cage claws 15 and accumulates on the claw inner diameter surfaces 23, and then overflows from the claw inner diameter surfaces 23, the overflowing grease passes through the grease passing grooves 25 and moves radially outward by centrifugal force. This allows grease inside the bearing to circulate without passing near the seal member 5, making it possible to effectively prevent grease circulating inside the bearing from reaching the seal portion between the seal member 5 and the inner ring 1.

[0067] Furthermore, in the grease-sealed ball bearing of this embodiment, the grease passage grooves 25 are formed with a depth that extends axially from the tip of the retainer claw portion 15 to the base of the retainer claw portion 15 beyond the pitch circle P. Therefore, compared to the comparative example shown in Figure 17, the volume of the retainer claw portion 15 can be reduced by the amount of the grease passage grooves 25, making it possible to increase the amount of grease sealed in the bearing space 3.

[0068] Furthermore, as shown in Figure 5, in the grease-sealed ball bearing of this embodiment, the axial length of the retainer claw portion 15 is set to be longer than the radius of the ball 4, and the inner diameter of the non-inclined inner diameter surface 23b of the claw inner diameter surface 23 is set to be smaller than the pitch circle P, so that the retention of the ball 4 by the retainer claw portion 15 is more stable than in a bearing in which the inner diameter of the non-inclined inner diameter surface 23b of the claw inner diameter surface 23 is set to be larger than the pitch circle P.

[0069] Furthermore, the grease-sealed ball bearing of this embodiment has a larger amount of grease packed in it than a normal grease-sealed ball bearing, and is less susceptible to grease leakage, so it is possible to extend the life (grease life) of bearings that are prone to poor lubrication due to grease degradation and the like. As a result, this grease-sealed ball bearing can be suitably used as a bearing that supports a rotating shaft that rotates at high speed, such as the rotating shaft that receives the rotation of the electric motor of an electric vehicle, or the rotating shaft of a hybrid electric vehicle that uses an electric motor as an auxiliary driving force for the engine. Specifically, this grease-sealed ball bearing has a dmn value (pitch circle diameter dm of balls 4 (mm) × rotation speed n (min -1 )) is particularly suitable for use as a high-speed rotation ball bearing that rotates in a high-speed rotation range where the Ratio of Rotational Force to Rotational Force is 1 million or more.

[0070] Furthermore, in the grease-sealed ball bearing of this embodiment, the radial thickness of the tip end portion of the cage claws 15 is smaller than the radial thickness of the base end portion of the cage claws 15, so the radial deflection of the cage claws 15 that occurs when subjected to centrifugal force can be kept small. As a result, it is possible to prevent the size of the gap between the pocket surfaces 21 of the cage claws 15 and the surfaces of the balls 4 from changing due to deflection of the cage claws 15 when the bearing rotates at high speed.

[0071] 21 and 22 show the results of an analysis of the amount of radial displacement due to deflection of the cage claw portions 15 that occurs when the bearing is rotated at high speed, assuming that the resin composition constituting the cage claw portions 15 is the same. Fig. 21 shows an analysis of the amount of radial displacement due to deflection of each portion of the cage claw portions 15 when an analytical model of the comparative greased ball bearing shown in Fig. 16 is created, with the outer diameter of the outer ring 2 being 62 mm and the inner diameter of the inner ring 1 being 30 mm, and the inner ring 1 of the analytical model is rotated at 20,000 rpm. Fig. 22 shows an analysis of the amount of radial displacement due to deflection of each portion of the cage claw portions 15 when an analytical model of the first embodiment of the greased ball bearing shown in Fig. 1 is created, with the outer diameter of the outer ring 2 being 62 mm and the inner diameter of the inner ring 1 being 30 mm, and the inner ring 1 of the analytical model is rotated at 20,000 rpm. 21 and 22, it can be seen that in the comparative example shown in Fig. 21, the tips of the cage claw portions 15 are displaced in the radial direction by approximately 0.8 mm due to deflection of the cage claw portions 15 caused by centrifugal force, whereas in the first embodiment shown in Fig. 22, the radial displacement of the tips of the cage claw portions 15 is kept to less than 0.4 mm (approximately half that of the comparative example). Furthermore, a similar analysis was performed using the same analytical model when the inner ring 1 was rotated at 30,000 rpm. As a result, it was confirmed that in the analytical model of the comparative example shown in Fig. 21, the tips of the cage claw portions 15 are displaced in the radial direction by approximately 1.7 mm, whereas in the analytical model of the first embodiment shown in Fig. 22, the radial displacement of the tips of the cage claw portions 15 is kept to approximately 0.7 mm.

[0072] 9 to 11 show a second embodiment of the present invention. In the first embodiment, the annular portion inner diameter surface 18 is a cylindrical surface formed so that the radial position does not change over the entire circumference, whereas in the second embodiment, a grease-receiving recess 26 is formed in the annular portion inner diameter surface 18, but the other configurations are the same. Therefore, hereinafter, parts corresponding to those in the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0073] 9 and 11, a grease accommodating recess 26 is formed in the inner diameter surface 18 of the annular portion, extending axially through the middle position between circumferentially adjacent balls 4. The grease accommodating recess 26 has a shape that gradually becomes shallower from the middle position between circumferentially adjacent balls 4 toward both sides in the circumferential direction.

[0074] 10, the grease accommodating recess 26 is formed so that the radial position of the inner surface of the grease accommodating recess 26 does not change along the axial direction. The grease accommodating recess 26 is formed to penetrate the cage annular portion 14 in the axial direction and is formed to partially extend into the end of the cage claw portion 15 on the cage annular portion 14 side. The inclination configuration of the claw inner diameter surface 23 is the same as in the first embodiment.

[0075] As shown in Figure 10, the grease-sealed ball bearing of this embodiment has a grease accommodating recess 26 formed on the inner diameter surface 18 of the annular portion. Therefore, even if grease accumulates on the inner diameter surface 18 of the annular portion, the grease can be introduced into the grease accommodating recess 26, thereby preventing the grease from reaching the sealing portion between the sealing member 5 and the inner ring 1 shown in Figure 2.

[0076] A third embodiment of the present invention is shown in Figure 12. In the first embodiment, as shown in Figure 8, the pocket surface 21 and the claw inner diameter surface 23 intersect to form a sharp edge, whereas in the third embodiment, a chamfer 27 is provided at the edge where the pocket surface 21 and the claw inner diameter surface 23 intersect, but the other configurations are the same.

[0077] A chamfer 27 of 0.5 mm or more is provided at the edge where the pocket surface 21 and the claw inner diameter surface 23 intersect. In the drawing, the chamfer 27 is an R-chamfer with an arc-shaped cross section and a radius of 0.5 mm or more. The chamfer 27 may be a C-chamfer with a cross section formed by removing a width of 0.5 mm or more from the pocket surface 21 and the claw inner diameter surface 23 along the direction of each surface, and connecting the two diagonally in a straight line.

[0078] The grease-sealed ball bearing of this embodiment has chamfers 27 of 0.5 mm or larger at the edges where the pocket surfaces 21 and the claw inner diameter surfaces 23 intersect, which makes it possible to prevent the cage claws 15 from scraping off grease from the surfaces of the balls 4. In addition, the grease that accumulates in the chamfers 27 can effectively lubricate the surfaces of the balls 4.

[0079] As shown in FIG. 13, a grease receiving recess 26 similar to that in the second embodiment may be additionally formed.

[0080] A fourth embodiment of the present invention is shown in Figure 14. In Figure 14, cage claw portions 15 are formed with grease grooves 28 that extend radially across pocket surfaces 21. Grease grooves 28 are formed at positions that intersect with pitch circles P (see Figure 5) of balls 4. By providing these grease grooves 28, the surfaces of balls 4 can be effectively lubricated by the grease that accumulates in grease grooves 28 and the grease that accumulates on claw inner diameter surfaces 23.

[0081] 15 shows a fifth embodiment of the present invention. In FIG. 15, the claw inner diameter surface 23 is composed of an inclined inner diameter surface 23a formed at the base end of the cage claw portion 15, a non-inclined inner diameter surface 23b that connects to the tip side of the cage claw portion 15 relative to the inclined inner diameter surface 23a, and a tip inclined surface 23c that connects to the tip side of the cage claw portion 15 relative to the non-inclined inner diameter surface 23b. Here, the tip of the tip inclined surface 23c is located radially outward from the pitch circle P, while the non-inclined inner diameter surface 23b is located radially inward from the pitch circle P. Even with this configuration, as in the first embodiment, the inner diameter of the non-inclined inner diameter surface 23b of the claw inner diameter surface 23 is set smaller than the pitch circle P so that the radially inner edge 22 of the pocket surface 21 is located radially inward from the pitch circle P. This ensures stable retention of the balls 4 by the cage claw portion 15.

[0082] In the above embodiments, the inner ring 1 has been described as a hollow annular member having an inner ring raceway groove 11 formed on its outer periphery, but the inner ring 1 does not necessarily have to be a hollow annular member, and it is also possible to use, for example, a solid member (shaft body) having an inner ring raceway groove 11 formed directly on its outer periphery with which the balls 4 roll and make contact. In short, the inner race may be any inner member having, on its outer periphery, an annular inner ring raceway groove with which the balls roll and make contact.

[0083] Furthermore, in the above embodiments, the outer ring 2 has been described as a hollow annular member with the outer ring raceway groove 8 formed on its inner periphery, but the outer ring 2 does not necessarily have to be a hollow annular member, and it is also possible to use, for example, a bearing housing with the outer ring raceway groove 8 with which the balls 4 roll and make contact formed directly on its inner periphery as the outer ring 2. In short, the outer race may be any outer member having, on its inner periphery, an annular outer ring raceway groove with which the balls roll and make contact.

[0084] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0085] 1. Inner circle 2 outer ring 3 Bearing space 4 balls 5 Sealing material 7 Cage 14 Retainer ring 15 Cage claw part 16 Bottom of pocket 17 Outer diameter surface of the annular part 18 Inner diameter surface of the annular part 19 Seal facing surface 20 Tapered surface for grease release 21 Pocket side 22 Radial inner edge of pocket surface 23 Claw inner diameter surface 25 Grease passage groove 26 Grease receiving recess 27 Chamfering 28 Grease groove C: The position where the pocket bottom and the inner diameter surface of the annular part intersect Pitch circle

Claims

1. Inner circle (1) and an outer ring (2) provided coaxially on the radially outer side of the inner ring (1); a plurality of balls (4) installed in an annular bearing space (3) formed between the inner ring (1) and the outer ring (2); an annular seal member (5) provided at one axial end of the bearing space (3); Grease sealed in the bearing space (3); a cage (7) for holding the plurality of balls (4), The cage (7) has a cage annular portion (14) extending in the circumferential direction, and cantilever-shaped cage claw portions (15) extending in the axial direction from the cage annular portion (14) between the balls (4) adjacent in the circumferential direction, In a grease-sealed ball bearing, the cage claw portion (15) has a pocket surface (21) facing the surface of the ball (4), and a claw inner diameter surface (23) extending circumferentially from a radially inner edge (22) of the pocket surface (21) so as to face the outer periphery of the inner ring (1), The claw inner diameter surface (23) is provided with a grease guide inclination that is displaced radially outward from the root side of the cage claw portion (15) toward the tip side of the cage claw portion (15), The cage annular portion (14) has, in a cross section passing through the center of the ball (4) and perpendicular to the circumferential direction, a pocket bottom (16) that faces the ball (4) in the axial direction, and an annular portion inner diameter surface (18) that extends in the axial direction from the radial inner end of the pocket bottom (16) and faces the outer periphery of the inner ring (1) in the radial direction, The inclination of the claw inner diameter surface (23) is set such that the inclination start position is a position (C) where the pocket bottom (16) and the annular portion inner diameter surface (18) intersect, A grease receiving recess (26) is formed on the inner diameter surface (18) of the annular portion, the recess (26) extending axially through an intermediate position between adjacent balls (4) in the circumferential direction, The grease-sealed ball bearing is characterized in that the grease-receiving recess (26) has a shape that is inclined so that it gradually becomes shallower toward both sides in the circumferential direction.

2. 2. The grease-sealed ball bearing according to claim 1, wherein the entire radially inner surface of the retainer claw portion (15) is disposed radially outward of the annular portion inner diameter surface (18).

3. 3. A grease-sealed ball bearing according to claim 1, wherein the retainer annular portion (14) further has a seal-opposing surface (19) that faces the seal member (5) in the axial direction, and a grease-releasing tapered surface (20) that connects the seal-opposing surface (19) and the annular portion inner diameter surface (18) at an angle.

4. The retainer annular portion (14) has an annular portion outer diameter surface (17) that faces the inner periphery of the outer ring (2) in the radial direction, 4. A grease-sealed ball bearing according to claim 1, wherein a radial gap between the outer periphery of the inner ring (1) and the inner diameter surface (18) of the annular portion is set larger than a radial gap between the inner periphery of the outer ring (2) and the outer diameter surface (17) of the annular portion.

5. A grease-sealed ball bearing as described in any one of claims 1 to 4, wherein the retainer claw portion (15) has a grease passage groove (25) formed therein, the grease passage groove (25) extending radially through the intermediate position between circumferentially adjacent balls (4) with a depth extending axially from the tip of the retainer claw portion (15) to the base side of the retainer claw portion (15) beyond the pitch circle (P) connecting the centers of the plurality of balls (4).

6. The axial length of the cage claw portion (15) is set to be longer than the radius of the ball (4), 6. A grease-sealed ball bearing according to claim 1, wherein the inner diameter of the claw inner diameter surface (23) is set smaller than a pitch circle (P) connecting the centers of the plurality of balls (4) so ​​that the radially inner edge (22) of the pocket surface (21) is located radially inward of the pitch circle (P).

7. 7. A grease-sealed ball bearing according to claim 1, wherein a chamfer (27) of 0.5 mm or more is provided on the edge where the pocket surface (21) and the claw inner diameter surface (23) intersect.

8. 8. A grease-sealed ball bearing according to claim 1, wherein the cage claws (15) are formed with grease grooves (28) extending radially across the pocket surface (21).

9. 9. The grease-sealed ball bearing according to claim 1, wherein the cage (7) is formed from a resin composition in which a fiber reinforcement material is added to a resin material.

10. A grease-sealed ball bearing according to any one of claims 1 to 9, wherein the amount of grease sealed is set to 38% or more of the total space volume, which is the volume of the bearing space (3) minus the volume of the retainer (7) and the volume of the plurality of balls (4).

11. A grease-sealed ball bearing according to any one of claims 1 to 10, wherein the amount of grease sealed in is set to 100% or more of the static space volume, which is the volume of the bearing space (3) minus the volume of the area through which the retainer (7) and the plurality of balls (4) pass when the bearing is rotating.

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