Rolling bearing

Abstract

This rolling bearing (1) comprises an inner ring (2), an outer ring (3), a plurality of balls (5), and a retainer (6) in which pockets (12) for holding the balls (5) are formed. The retainer (6) includes: a plurality of pocket wall parts (13) arranged at regular intervals in the circumferential direction; and a plurality of connecting parts (14) that connect the pocket wall parts (13, 13) adjacent to each other in the circumferential direction. Each of the pocket wall parts (13) is provided with an evacuation part (EP) that loses contact with the ball (5) when the retainer (6) moves relative to the balls (5) in the axial direction. A contact surface (Cf) of the pocket wall part (13) in contact with the ball (5) is asymmetric with respect to a plane passing through a pocket center (PO) of each of the pockets (12) and the rotation axis of the retainer (6).

Description

Rolling bearings Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-109117, filed July 5, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a rolling bearing incorporating, for example, a cage made of synthetic resin.

[0003] Synthetic resin cages for use in rolling bearings have been proposed (see Patent Documents 1 and 2). These synthetic resin cages are formed by engaging two annular bodies of the same shape.

[0004] In rolling bearings lubricated with grease, it is known that grease adhering to the surfaces of rotating balls becomes trapped between cage pockets or raceways, affecting parameters such as bearing temperature rise, vibration, and noise levels. In other words, grease flow inside the bearing affects bearing performance. In recent years, there has been an increasing demand for higher bearing speeds, and cages, which have a significant impact on grease flow, need to be made compatible with these high speeds.

[0005] In the synthetic resin cage of Patent Document 1, notches 70a, 70b are provided on the inner and outer diameter surfaces of pocket wall portion 70 in order to scrape off grease adhering to the balls, as shown in Figure 14. In the synthetic resin cage of Patent Document 2, in consideration of deformation of the cage due to centrifugal force, the relief shape in the pocket axial direction is a cylindrical surface that extends in the radial direction of the cage on the inner diameter side of the ball pitch circle.

[0006] JP 2020-159548 A Patent No. 5876237 A

[0007] In Patent Document 1, the ability to scrape off grease adhering to the ball surface is improved and break-in time is reduced by providing notches 70a, 70b on the inner or outer diameter surface of pocket wall 70. In addition, heat generation is suppressed by scraping off some of the grease remaining in the stationary space with the notches 70a, 70b and supplying base oil between the ball and the pocket.

[0008] Although the shape of the notches 70a, 70b in Patent Document 1 is effective, centrifugal force acting on the cage rotating at high speed causes the pocket wall 70 to deform in a direction that reduces the axial clearance between the balls and the pocket wall 70. Furthermore, because the behavior of the cage during high-speed rotation is complex, there is a risk that the axial movement of the cage during rotation will cause interference between the pocket wall 70 and the balls in the axial direction. As a result, oil burn, abnormal wear, heat generation, etc. may occur, and there is a concern that the oil film parameters of the bearing may deteriorate.

[0009] Patent Document 2 discloses a method for preventing axial interference between the pocket wall 70 and the balls due to deformation of the cage caused by centrifugal force. In Patent Document 2, the axial relief shape of the pocket wall 70 is a cylindrical surface extending in the radial direction of the cage. This suppresses interference between the pocket wall 70 and the balls even if deformation occurs in the axial portion of the pocket wall 70 due to centrifugal force. As a result, even if the pocket wall 70 is deformed by centrifugal force, there is no interference between the pocket wall 70 and the balls, which prevents oil burn, abnormal wear, and the like.

[0010] However, the force acting on the cage constantly changes during rotation depending on the operating conditions, the quality of the bearing, the rotational speed, etc. When an axial force F ( FIG. 16B ) is generated on the rotating cage, the cage moves axially, and contact occurs between the pocket wall 70 and the balls at points where the axial clearance is small. In this case, if the pockets have the same R-shape as in FIG. 15 , even when there is a relief 71 as in FIG. 16A , the cage will contact at two axial points Cf, Cf (one point each at the front and back of the direction of travel) as in FIG. 16B . Because these two points Cf, Cf exist on the same contact circumference, excess oil adhering to the balls 72 is scraped off, making it easier for heat to be generated by contact.

[0011] An object of the present invention is to provide a rolling bearing that can suppress excessive temperature rise and wear.

[0012] The rolling bearing of the present invention is a rolling bearing comprising an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a retainer that holds each ball, wherein the retainer has a plurality of pocket wall portions arranged at regular intervals in the circumferential direction and a plurality of connecting portions that connect adjacent pocket wall portions in the circumferential direction, the balls are held in pockets formed by the pocket wall portions, and each of the pocket wall portions is provided with a concave relief portion that does not come into contact with the balls when the retainer moves axially relative to the balls, and the contact surface of the pocket wall portion that comes into contact with the balls is asymmetrically configured on both sides of a plane that passes through the pocket center of each pocket and the rotation axis of the retainer, respectively.

[0013] With this configuration, during operation of the rolling bearing, the cage moves axially and comes into contact with the balls due to, for example, uneven distribution of lubricant such as grease. In this case, the contact points (contact surfaces) of the cage are located at different positions asymmetrically relative to the ball's rotation axis. Here, the "ball's rotation axis" refers to the axis that serves as the center of rotation when the ball rotates in conjunction with the rotation of the inner or outer ring. In this case, the multiple contact surfaces of the cage are not located on the same contact circumference, making it difficult to stabilize axial contact. This prevents excessive grease scraping and prevents excessive temperature rise, oil burn, abnormal wear, etc.

[0014] The cage may have two annular bodies overlapping each other in the axial direction, each annular body having a plurality of the pocket wall portions and a plurality of the connecting portions, and the two annular bodies may be joined by overlapping each other at the connecting portions. Each annular body may be formed, for example, by injection molding a synthetic resin using a mold. In this case, for example, by making the dimensional accuracy of the mold less than that of a conventional structure, the contact surface of the cage can be configured asymmetrically with respect to the rotation axis of the balls. Since the dimensional accuracy of the mold can be made less than that of a mold of a conventional structure, the manufacturing cost of the mold can be reduced, and as a result, the manufacturing cost of the cage can be reduced. Therefore, excessive temperature rise, oil burn, abnormal wear, etc. can be prevented while reducing the overall cost of the rolling bearing.

[0015] When the pocket wall and the ball make two-point contact in the axial direction in a cross section taken along a plane perpendicular to a radial line passing through the center of the pocket, the rotation axis of the ball may be offset from the axial line passing through the center of the pocket. Here, "axial direction" refers to the direction along the cage axis, which is the rotation axis of the cage. In this case, the two contact points of the cage are not located on the same contact circumference, which reliably prevents excessive grease scraping and prevents excessive temperature rise, oil burn, abnormal wear, etc.

[0016] The radius of curvature of the curved surface that forms the inner surface passing through one of the two contact points may be different from the radius of curvature of the curved surface that forms the inner surface passing through the other contact point. This configuration ensures that the rotation axis of the balls can be shifted reliably relative to the pocket axis. As a result, the axial contact of the cage becomes less stable, preventing excessive heating, oil burn, abnormal wear, etc.

[0017] The center of the curved surface that forms the inner surface passing through one of the two contact points may be at a different position from the center of the curved surface that forms the inner surface passing through the other contact point. In this case, the two contact points of the cage are not located on the same contact circumference. As a result, excessive grease scraping can be reliably prevented, and excessive temperature rise, oil burn, abnormal wear, etc. can be prevented.

[0018] The circumferential width of the relief portion may be asymmetric with respect to an axial line passing through the center of the pocket. In this case, too, the two contact points of the cage are not located on the same contact circumference. As a result, excessive grease scraping can be reliably prevented, and excessive temperature rise, oil burn, abnormal wear, etc. can be prevented.

[0019] Each pocket wall may have contact portions at both circumferential ends of its inner surface that contact the balls at multiple points spaced apart in the axial direction. In this case, the cage contacts the balls at multiple points in the circumferential direction, thereby suppressing the force that would otherwise move the cage in the axial direction. This stabilizes the cage's position and more reliably prevents excessive heating, oil burn, abnormal wear, and the like.

[0020] The balls may be ceramic balls, which have a lower specific gravity than steel balls made of bearing steel, etc., and thus can increase the speed of the rolling bearing and improve heat resistance.

[0021] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0022] The present invention will be more clearly understood from the following description of preferred embodiments, taken in conjunction with the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present invention. The scope of the present invention is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.

[0023] Fig. 1 is a longitudinal sectional view of a rolling bearing according to a first embodiment of the present invention.

[0024] Fig. 2 is a front view of a cage of the rolling bearing as viewed from the axial direction.

[0025] Fig. 3 is a sectional view taken along line III-III in Fig. 2.

[0026] Fig. 4 is a sectional view taken along line IV-IV in Fig. 2.

[0027] Fig. 5 is a partially enlarged view of a main part of the cage.

[0028] Fig. 6 is a partially enlarged view of a cage of a rolling bearing according to a second embodiment of the present invention.

[0029] Fig. 7 is a partially enlarged view of a cage of a rolling bearing according to a third embodiment of the present invention.

[0030] Fig. 8 is a sectional view of a main part of a cage of a rolling bearing according to a fourth embodiment of the present invention.

[0031] Fig. 9 is a sectional view of a pocket wall of the cage.

[0032] Fig. 10 is a partially enlarged view of a main part of the cage.

[0033] Fig. 11 is a partially enlarged view showing a contact portion of the cage with the balls.

[0034] Fig. 12 is a partially enlarged view of a cage of a rolling bearing according to a fifth embodiment of the present invention.

[0035] Fig. 13 is a partially enlarged view of a cage of a rolling bearing according to a sixth embodiment of the present invention. Fig. 14 is a partially enlarged cross-sectional view of a retainer of a rolling bearing according to a seventh embodiment of the present invention. Fig. 15 is a cross-sectional view of a main part of a retainer of a rolling bearing according to an eighth embodiment of the present invention. Fig. 16 is a conceptual diagram showing an example in which a rolling bearing of the present invention is applied to a motor. Fig. 17 is a front view of a conventional retainer as seen from the axial direction. Fig. 18 is a cross-sectional view taken along line XV-XV in Fig. 14. Fig. 19 is a partially enlarged view of a conventional retainer. Fig. 20 is a partially enlarged view of a conventional retainer showing an example in which the conventional retainer has moved in the axial direction.

[0023] [First embodiment] A rolling bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 5. <Regarding the rolling bearing> The rolling bearing 1 in Figure 1 is a deep groove ball bearing that is lubricated with grease. The rolling bearing 1 comprises an inner ring 2, an outer ring 3, a plurality of balls 5, a cage 6, and a seal 4. The balls 5 are rolling elements that are interposed between the rolling surfaces 2a, 3a of the inner and outer rings 2, 3. The balls 5 are steel balls or ceramic balls. Pockets 12 are formed in the cage 6, and each ball 5 is held in the pocket 12.

[0024] In this specification, a rolling bearing may be simply referred to as a "bearing." In this specification, the direction of the bearing center axis AX, which is the axis of the bearing, or the direction parallel to the bearing center axis AX is referred to as the "axial direction," and the direction perpendicular to the bearing center axis AX is referred to as the "radial direction." The circumferential direction around the bearing center axis AX is referred to as the "circumferential direction." In addition, in the radial direction, the side facing the bearing center axis AX is referred to as the "inner diameter side," and the side away from the bearing center axis AX is referred to as the "outer diameter side."

[0025] An annular space is formed between the outer peripheral surface of the inner ring 2 and the inner peripheral surface of the outer ring 3, and openings at both axial ends of this annular space are closed by seals 4, 4. Lubricating grease is sealed in the closed annular space. A seal mounting groove 7 is formed in the inner peripheral surface of the outer ring 3, and an inner ring seal groove 8 is formed in the outer peripheral surface of the inner ring 2. The seal 4 in this embodiment is a non-contact seal in which the lip does not come into contact with the inner ring seal groove 8. The seal 4 has a core metal and rubber material, and the rubber material is molded onto the core metal. The outer peripheral edge of the seal 4 is fitted into and fixed in the seal mounting groove 7 of the outer ring 3.

[0026] <Regarding the Cage> The cage 6 in FIG. 2 is of a rolling element guided type. Here, a "rolling element guided type cage" refers to a cage in which the cage contacts only the rolling elements (balls). The cage 6 includes two annular bodies 10, 10 made of synthetic resin that overlap each other in the axial direction, as shown in FIGS. 3 and 4 . When the two annular bodies 10, 10 are joined together, as shown in FIG. 2 , the outer diameter surfaces of the annular bodies 10, 10 have the same diameter except for the cutout portion 13b, and the inner diameter surfaces of the annular bodies 10, 10 have the same diameter except for the cutout portion 13a. Each annular body 10 is formed, for example, by injection molding a synthetic resin. The two annular bodies 10, 10 have the same shape and can be molded using the same mold. Each annular body 10 may be formed by machining, or may be formed by a combination of molding using a mold and machining.

[0027] The synthetic resin may be injection moldable and have sufficient heat resistance, oil resistance, mechanical strength, etc., as a cage material. Examples of synthetic resins include polyolefin resins, thermosetting resins, engineering plastics, and super engineering plastics. From the viewpoint of heat resistance, the melting point of the resin material of the cage 6 is preferably 200°C to 360°C, and more preferably 200°C to 350°C. If the melting point is below 200°C, the resin may melt or wear abnormally due to frictional heat generated by the sliding of the balls and pocket walls. From the viewpoint of strength, 15 to 45 mass % of glass fiber, carbon fiber, aramid fiber, etc. may be added to the resin.

[0028] 3 and 4, each annular body 10 has a plurality of semi-cylindrical pocket wall portions 13 and a plurality of connecting portions 14. The plurality of pocket wall portions 13 are arranged at regular intervals in the circumferential direction. The inner surface 13c of each pocket wall portion 13 forms the inner surface of the pocket 12 that holds the ball 5 (FIG. 1). The plurality of connecting portions 14 connect the pocket wall portions 13 that are adjacent in the circumferential direction.

[0029] As shown in Figure 4, the connecting portion 14 has a mating surface 15 that comes into surface contact when the two annular bodies 10, 10 are joined. Figure 4 is a cross-section of the pocket wall portion 13 taken along a plane perpendicular to a radial line passing through the pocket center P0, and is a cross-section taken along line IV-IV in Figure 2. Here, the "pocket center P0" refers to the center of the radius of curvature that constitutes the inner surface of the pocket wall portion 13. Near the circumferential center of the connecting portion 14, there are formed a connecting claw 16 that protrudes in the axial direction and a connecting hole 17 into which the connecting claw 16 of the other annular body 10 is inserted.

[0030] A hook portion 16a is formed at the axial tip of the connecting claw 16, and the hook portion 16a of one annular body 10 engages with a step portion 17a formed on the inner surface of the connecting hole 17 of the other annular body 10. This engagement prevents the connecting claw 16 from slipping out of the connecting hole 17, and the two annular bodies 10, 10 are joined together by overlapping them.

[0031] The connecting portion 14 has a protruding wall portion 20 and an accommodating recess 21. The protruding wall portion 20 is provided at one circumferential end of the mating surface 15 of one annular body 10 so as to protrude in the axial direction. The accommodating recess 21 is provided at the other circumferential end of the mating surface 15 of one annular body 10, and accommodates the protruding wall portion 20 of the other annular body 10. Since the connecting portion 14 has the protruding wall portion 20 and the accommodating recess 21, the mating surfaces 15 of the two annular bodies 10, 10 are positioned offset from the axial center of the pocket 12.

[0032] When the two annular bodies 10, 10 are joined together, the space formed by the axially opposing portions of the inner surfaces 13c of the pocket walls 13, 13 and the circumferentially opposing portions of the connecting portions 14, 14 is the pocket 12.

[0033] When the two annular bodies 10, 10 are joined together, a circumferential gap 22 and an axial gap 23 are generated between the protruding wall portion 20 and the accommodating recess 21. This prevents interference between the protruding wall portion 20 and the accommodating recess 21 due to differential shrinkage after the annular body 10 is injection molded, and the mating surfaces 15 of the connecting portions 14 of the two annular bodies 10 are tightly attached to each other.

[0034] <Regarding the Relief Portions> Concave relief portions EP are provided on both axial sides of the inner surface 13c of each pocket wall portion 13. The relief portions EP are portions that do not come into contact with the balls 5 (FIG. 5) when the cage 6 moves axially relative to the balls 5. As shown in FIG. 5, the relief portions EP are formed on both circumferential sides of the pocket axis PK. The relief portions EP are partial cylindrical or partial spherical surfaces that extend a predetermined distance in an arc shape. Here, the "pocket axis PK" is an axial line that passes through the pocket center P0 and is the axis of the pocket 12 in the cage axial direction C1. Furthermore, the "axis center of the cage axial direction C1" is synonymous with the rotational axis of the cage 6.

[0035] Asymmetrical Configuration, etc. As shown in Fig. 4, in each annular body 10, partial spherical surfaces R1 and R2 having different radii of curvature are connected to both circumferential edge portions of the relief portion EP via flat surfaces P5, P5 that are steps. As shown in Fig. 5, these partial spherical surfaces R1 and R2 have partial spherical shapes with spherical surfaces that are slightly larger in diameter than the diameter of the ball 5.

[0036] 3 and 4, in each annular body 10, one partial spherical surface R1 is located near the axial center of the inner surface of the pocket 12, and the other partial spherical surface R2 extends a predetermined distance from the gap 23 to the nearest flat surface P5. As shown in FIG. 4, when the two annular bodies 10 are joined, the pair of partial spherical surfaces R1, R1 face each other with the pocket center P0 as the reference (center). The spherical center of the partial spherical surface R1 is the pocket center P0. The pair of partial spherical surfaces R2, R2 also face each other with the pocket center P0 as the reference (center).

[0037] As shown in Figures 4 and 5, in a cross section of the pocket wall portion 13 cut along a plane perpendicular to a radial line passing through the pocket center P0, the contact surface Cf of the pocket wall portion 13 that comes into contact with the ball 5 is asymmetric (left-right asymmetric in Figure 5) on both sides of the plane that passes through the pocket center P0 of each pocket 12 and the rotation axis C1 of the retainer 6.

[0038] In other words, in the cross section of Fig. 4, when the pocket wall 13 and the balls 5 are in two-point contact in the axial direction C1, the rotation axis Ra of the balls 5 is offset from the axial line (pocket axis PK) passing through the pocket center P0, as shown in Fig. 5. In this case, the inner surface 13c passing through one contact point (contact surface Cf) when the pocket wall 13 and the balls 5 are in two-point contact in the axial direction C1 and the inner surface 13c passing through the other contact point (contact surface Cf) are curved surfaces with different radii of curvature. In this example, the radius of curvature of the partial spherical surface R1 is set larger than the radius of curvature of the partial spherical surface R2 (R1 > R2).

[0039] In this embodiment, the inner surface 13c including one contact surface Cf and the inner surface 13c including the other contact surface Cf are each spherical surfaces with a single radius of curvature. However, the inner surface 13c is not limited to a spherical surface with a single radius of curvature. The inner surface 13c including one contact surface Cf and the inner surface 13c including the other contact surface Cf may be, for example, a compound curved surface in which multiple curved surfaces are smoothly connected. However, even in the compound curved surface, when the inner surface 13c and the balls 5 make two-point contact in the cage axial direction C1, the radius of curvature of the contact surface Cf, which is one of the contact points, is different from the radius of curvature of the contact surface Cf, which is the other contact point (R1 ≠ R2).

[0040] <Regarding the Cutout Portions> As shown in FIG. 2 , cutout portions 13a and 13b are provided on the inner and outer diameter surfaces of the pocket wall portion 13, respectively. The cutout portions 13a and 13b make the band width W1, which is the radial dimension of the pocket wall portion 13, smaller than the radial dimension W2 of the connecting portion 14. The cutout portion 13a on the inner diameter surface has a curved surface shape that forms a concave curve on the radially outward side when viewed from the bearing axial direction. The cutout portions 13b on the outer diameter surface have a curved surface shape that forms a concave curve on the radially inward side when viewed from the bearing axial direction. These cutout portions 13a and 13b are formed, for example, during injection molding of the annular body 10, but may also be formed by machining or the like after injection molding. However, the cutout portions 13a and 13b are not essential.

[0041] In each pocket wall 13, the deepest part of the cutout 13a on the inner diameter surface is located at the circumferential middle part of the inner diameter surface. Also, the deepest part of the cutout 13b on the outer diameter surface is located at the circumferential middle part of the outer diameter surface. That is, in each pocket wall 13, the band width W1 is smallest at the circumferential middle part and gradually increases from the circumferential middle part to both sides in the circumferential direction along the curved surface shape.

[0042] <Operation and Effect> According to the rolling bearing 1 of Fig. 1 described above, during bearing operation, the cage 6 moves in the axial direction and comes into contact with the balls 5 due to uneven distribution of lubricant such as grease. At this time, as shown in Fig. 5, the contact surfaces Cf of the cage 6 are positioned asymmetrically on both sides of a plane that passes through the pocket center P0 of each pocket 12 and the rotation axis of the cage 6. In this case, the multiple contact surfaces Cf, Cf of the cage 6 are not positioned on the same contact circumference, making it difficult to stabilize axial contact. This prevents excessive grease from being scraped off, and can prevent excessive temperature rise, oil burn, abnormal wear, etc.

[0043] Each annular body 10 shown in Fig. 2 is formed by, for example, injection molding synthetic resin. In this case, for example, by making the dimensional accuracy of the mold less than that of a conventional structure, the contact surface Cf of the cage 6 shown in Fig. 5 can be configured asymmetrically on both sides of a plane that passes through the pocket center P0 of each pocket 12 and the rotation axis of the cage 6. Since the dimensional accuracy of the mold can be made less than that of a conventional mold, the manufacturing cost of the mold can be reduced, and as a result, the manufacturing cost of the cage 6 can be reduced. Therefore, the overall cost of the rolling bearing can be reduced, and excessive temperature rise, oil burn, abnormal wear, etc. can be prevented.

[0044] In the cross section of FIG. 4 , when the pocket wall 13 and the balls 5 make two-point contact in the axial direction C1, the rotation axis Ra of the balls 5 is offset from the pocket axis PK, as shown in FIG. 5 . In this case, the two contact points of the cage 6 are not located on the same contact circumference, preventing excessive grease scraping. The inner surface 13c (curved surface) 13c passing through one point when the inner surface 13c and the balls 5 make two-point contact in the axial direction C1 has a different radius of curvature from the inner surface 13c (curved surface) passing through the other point. As a result, by offsetting the rotation axis Ra of the balls 5 from the pocket axis PK, the axial contact of the cage 6 becomes less stable. This prevents excessive heating, oil burn, abnormal wear, and the like. Furthermore, when the balls 5 are ceramic balls, their specific gravity is lower than that of steel balls made of bearing steel, for example, allowing for higher speeds in rolling bearings and improving heat resistance.

[0045] <Regarding Other Embodiments> In the following description, parts corresponding to matters previously described in each embodiment are assigned the same reference numerals, and duplicate explanations will be omitted. When only part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0046] 6, when the pocket wall 13 and the ball 5 are in two-point contact in the axial direction C1, the center Pa of the curved surface forming the inner surface 13c passing through one of the contact points (contact surface Cf) may be in a different position from the center Pb of the curved surface forming the inner surface 13c passing through the other contact point (contact surface Cf). During such two-point contact, the rotation axis Ra of the ball 5 is misaligned with the pocket axis PK.

[0047] With this configuration, when the cage 6 moves axially and comes into contact with the balls 5, the two contact points of the cage 6 are not located on the same contact circumference. As a result, excessive grease scraping is reliably prevented, and excessive temperature rise, oil burn, abnormal wear, etc. can be prevented.

[0048] In this configuration, the first inner surface 13c and the second inner surface 13c may be, for example, a compound curved surface in which multiple curved surfaces are smoothly connected. However, even in the compound curved surface, when the inner surface 13c and the ball 5 are in two-point contact in the axial direction C1, the center Pa of the curved surface passing through one point is in a different position from the center Pa of the curved surface passing through the other point.

[0049] 7, the circumferential width of the relief portion EP may be asymmetric with respect to an axial line passing through the pocket center PO (pocket axis PK in the cage axial direction C1). For example, the circumferential width of the relief portion EP may be set to A<B with respect to the pocket axis PK.

[0050] With this configuration, when the cage 6 moves axially and makes two-point contact with the balls 5, the two contact points of the cage 6 are not located on the same contact circumference, preventing excessive grease scraping. Also, during two-point contact, the rotation axis Ra of the balls 5 is misaligned with the pocket axis PK. Preventing excessive grease scraping can prevent excessive temperature rise, oil burn, abnormal wear, and the like. Even in this configuration, one inner surface 13c and the other inner surface 13c may be, for example, a compound curved surface in which multiple curved surfaces are smoothly connected.

[0051] 8 to 10B, circumferential contact portion with two contact points] <Regarding the contact portion> Any of the first to third embodiments may be combined. As shown in Fig. 8, at both circumferential ends of the inner surface 13c of each pocket wall portion 13, contact portions P are provided that come into contact with the balls 5 at multiple points spaced apart in the cage axial direction C1, as shown in Fig. 10B. Fig. 9 is a cross section of the pocket wall portion 13 taken along a plane perpendicular to a radial line passing through the pocket center PO.

[0052] Specifically, as shown in Figures 8 and 9, contact portions P are provided at both circumferential ends of the inner surface 13c of each pocket wall portion 13, which contact the outer periphery of the balls 5 at two points with a predetermined distance δ in the cage axial direction C1, as shown in Figures 10A and 10B. The distance δ between the two contact portions P, P shown in Figure 10B is determined appropriately depending on, for example, the bearing size, vibration test results, etc.

[0053] At both circumferential ends of each pocket 12 shown in Fig. 9, multiple (two in this example) tapered surfaces P2 are formed that are inclined at a predetermined angle α with respect to a plane that includes the cage axis and passes through the pocket center P0, as shown in Fig. 10A. As shown in Fig. 10B, a contact portion P is provided on each tapered surface P2. A tapered edge P3 at one circumferential end of each pocket 12, where adjacent tapered surfaces P2, P2 are connected, is located at the axial center of the pocket 12. The tapered edge P3 at the other circumferential end of each pocket 12 is also located at the axial center of the pocket 12.

[0054] As shown in Fig. 8 , using the tapered edge P3 of each pocket 12 as a reference, relief portions EP, EP which are partial cylindrical or partial spherical surfaces are connected on both sides in the axial direction C1 of the cage via tapered surfaces P2, P2, partial spherical surfaces R1, R2, and flat surfaces P5, P5 which are steps. As shown in Fig. 9 , the two tapered surfaces P2, P2 formed at one circumferential end of each pocket 12 are provided on one annular body 10. The two tapered surfaces P2, P2 formed at the other circumferential end of each pocket 12 are provided on the other annular body 10 that is joined to the first annular body 10.

[0055] With this configuration, the cage 6 contacts the balls at two points in the circumferential direction, thereby suppressing the force that would move the cage 6 in the axial direction. This makes the attitude of the cage 6 more stable, and it is possible to reliably prevent excessive temperature rise, oil burn, abnormal wear, and the like. Furthermore, because the force that would move the cage 6 in the axial direction is suppressed, the behavior of the cage 6 in the axial direction C1, particularly during high-speed rotation, is more stable than with conventional cages that contact the balls at one point in the circumferential direction of rotation. As a result, the surface pressure at the contact point P (FIG. 10B) is reduced, and wear is mitigated.

[0056] A plurality of tapered surfaces P2 are formed at both circumferential ends of each pocket 12, and are inclined with respect to a plane that includes the cage axis and passes through the pocket center P0, and each tapered surface P2 is provided with a contact portion P (FIG. 10B). In this case, each tapered surface P2 can be easily formed using a mold or the like, which reduces manufacturing costs.

[0057] The two tapered surfaces P2, P2 formed at one circumferential end of each pocket 12 are provided on one annular body 10. In this case, no force is generated in the direction separating the two annular bodies 10, 10, and stress is generated only on one of the two annular bodies 10, 10. As a result, excessive load is not applied to the coupling claws 16 (FIG. 2), and abnormalities in the coupling claws 16 can be prevented. Therefore, abnormalities in the cage 6 can be prevented in advance. In addition, the same effects as those of the above-mentioned embodiment are achieved.

[0058] 11A , a contact portion P that makes three-point contact may be provided at both circumferential ends of each pocket 12. In this case, the surface pressure at the contact portion P is further reduced compared to a conventional cage that makes contact at one point in the circumferential direction of rotation, thereby suppressing wear.

[0059] Sixth Embodiment: Compound Curved Surface At both circumferential ends of each pocket 12 shown in Fig. 11B, instead of each tapered surface P2 of Fig. 10B, a concave curved surface P7 as shown in Fig. 11B may be applied, and a contact portion P may be provided on each concave curved surface P7. Each concave curved surface P7 may be, for example, a cylindrical surface extending along the radial direction of each pocket 12. This configuration provides the same effects as the second embodiment.

[0060] 11C , tapered surfaces on each annular body] For example, under conditions of use at medium to low rotation speeds, as shown in FIG. 11C , each annular body 10 may be provided with a tapered surface P2, and each tapered surface P2 may be provided with a contact portion P. However, since a force is generated in the direction A1 in which the two annular bodies 10, 10 are separated from each other, this is not suitable for use at high rotation speeds.

[0061] [Eighth embodiment: angular contact ball bearing without split surface] As shown in Fig. 12, the cage 6 of the present invention can also be applied to a resin cage without split surfaces. In this case, the partial spherical surfaces R1 and R2 are smoothly connected. A resin cage without split surfaces is used, for example, as the cage 6 of an angular contact ball bearing. The cage 6 in Fig. 12 may be formed by machining the entire cage, or may be formed by combining molding with a mold and machining, etc.

[0062] <Rolling bearing for motor> As shown in Figure 13, the rolling bearing according to the above embodiment is used, for example, as rolling bearings 50, 50 for a motor 51. However, the rolling bearing according to the above embodiment can also be used for applications other than motors. When a rolling bearing for a motor is provided with a cage having the asymmetric configuration described above, abnormalities such as excessive temperature rise and wear can be suppressed. For this reason, the rolling bearing according to the above embodiment is particularly suitable for use in motors that operate at high speeds.

[0063] The present invention is not limited to the above embodiments, and various additions, modifications, and deletions are possible without departing from the spirit of the present invention. For example, the seal 4 in FIG. 1 may be a contact seal in which a lip contacts the inner ring seal groove 8. The seal 4 may also be a so-called shield plate made only of steel plate. The rolling bearing of the present invention may also be an open rolling bearing without the seal 4. Furthermore, one or both of the cutout portions 13a and 13b may not be provided.

[0064] Depending on the application and conditions of use of the bearing, oil may be used as a lubricant instead of grease. The rolling bearing of the above embodiment can also be used in machine tools, industrial machinery, vehicles, etc. Each annular body, or the entire cage without the aforementioned split surfaces, may be formed using a 3D printer or the like. Therefore, such forms are also included within the scope of the present invention.

[0065] REFERENCE SIGNS LIST 1... rolling bearing, 2... inner ring, 3... outer ring, 5... ball, 6... cage, 12... pocket, 13... pocket wall, 13c... inner surface, 14... connecting portion, Cf... contact surface, EP... relief portion, P... contact portion, PO... pocket center, PK... pocket axis, Ra... rotation axis

Claims

1. A rolling bearing comprising an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a cage that holds each ball, wherein the cage has a plurality of pocket wall portions arranged at regular intervals in the circumferential direction and a plurality of connecting portions that connect adjacent pocket wall portions in the circumferential direction, the balls are held in pockets formed by the pocket wall portions, and each of the pocket wall portions is provided with a concave relief portion that does not come into contact with the balls when the cage moves axially relative to the balls, and the contact surface of the pocket wall portion that comes into contact with the balls is asymmetric on both sides of a plane that passes through the pocket center of each pocket and the rotation axis of the cage.

2. A rolling bearing as described in claim 1, wherein when the pocket wall and the ball come into axial contact at two points in a cross section of the pocket wall cut by a plane perpendicular to a radial line passing through the center of the pocket, the rotation axis of the ball is offset from the axial line passing through the center of the pocket.

3. A rolling bearing as claimed in claim 2, in which the radius of curvature of the curved surface forming the inner surface passing through one of the two contact points is different from the radius of curvature of the curved surface forming the inner surface passing through the other contact point.

4. A rolling bearing as claimed in claim 2, in which the centre of the curved surface forming the inner surface passing through one of the two contact points is at a different position from the centre of the curved surface forming the inner surface passing through the other contact point.

5. A rolling bearing according to any one of claims 1 to 3, wherein the circumferential width of the relief portion is asymmetric with respect to an axial line passing through the center of the pocket.

6. A rolling bearing as claimed in any one of claims 1 to 3, wherein contact portions are provided at both circumferential ends of the inner surface of each of the pocket walls, which contact the balls at multiple points spaced apart in the axial direction.

7. A rolling bearing according to any one of claims 1 to 3, wherein the balls are ceramic balls.

Images