Jade Axle

Abstract

This suppresses abnormal noise from the ball bearing caused by cage runout. [Solution] The device comprises an inner ring 11, an outer ring 12, a plurality of balls 13 that are rotatable between the inner ring 11 and the outer ring 12, a retainer 14 that holds the plurality of balls 13 from both sides in the axial direction, and an annular grease member 15. The inner circumferential surface of the outer ring 12 has an outer ring raceway 12b on which the balls 13 roll, a guide surface 12c that guides the retainer 14 on one side in the axial direction from the outer ring raceway 12b, and a grease member on the other side in the axial direction from the outer ring raceway 12b. A ball bearing 10, comprising a fitting surface 12d against which the outer circumferential surface of member 15 abuts, wherein the grease member 15 has grease 151 on its entire or at least inner circumferential surface, is located between the fitting surface 12d and the outer circumferential surface of the cage 14 on the other axial side of the outer ring raceway 12b, and the radial gap G1 between the inner circumferential surface of the grease member 15 and the outer circumferential surface of the cage 14 is smaller than the radial gap G2 between the guide surface 12c and the outer circumferential surface of the cage 14.

Description

Technical Field

[0001] This disclosure relates to ball bearings.

Background Art

[0002] Ball bearings are used in various applications such as the spindle support of machine tools. For example, Patent Document 1 discloses an angular ball bearing including an inner ring, an outer ring, a plurality of balls, and a cage. Here, there is an outer-ring-guided ball bearing that suppresses the radial runout of the cage accompanying rotation by guiding the outer peripheral surface of the cage by the inner peripheral surface of the outer ring.

[0003] In Patent Document 1, in an outer-ring-guided ball bearing, in order to suppress the contact noise when the cage contacts the outer ring, an engaging portion that protrudes into the pocket is provided in the cage. Then, when the cage moves in the radial direction, after any one of the engaging portions engages with the balls in the pocket, the cage contacts the outer ring. Thus, since the contact of the cage with the outer ring occurs after the engagement of the balls with the engaging portion, the impact when the cage contacts the outer ring is alleviated, and the contact noise and the like are reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 relates to a technique for reducing contact noise by impact mitigation, and it cannot completely prevent the contact noise itself when the cage contacts the outer ring. For example, when the amount of wobbling of the cage increases due to high-speed rotation of the ball bearing or the like, a large contact noise may occur due to the cage contacting the outer ring relatively violently.

[0006] Furthermore, if the amount of oil between the cage and the outer ring decreases, in addition to the contact noise caused by the radial collision between the cage and the outer ring, contact noise (also called stick-slip noise) may occur due to circumferential friction between the cage and the outer ring.

[0007] In view of these issues, this disclosure aims to suppress abnormal noise in ball bearings caused by cage runout. [Means for solving the problem]

[0008] The ball bearing of the present disclosure comprises an inner ring, an outer ring, a plurality of balls rotatably provided between the inner ring and the outer ring, a cage that holds the plurality of balls from both sides in the axial direction, and an annular grease member, wherein the inner circumferential surface of the outer ring includes an outer ring raceway on which the balls roll, a guide surface that guides the cage on one side in the axial direction of the outer ring raceway, and a fitting surface on the other side in the axial direction of the outer ring raceway against which the outer circumferential surface of the grease member abuts, the grease member having grease on its entire or at least inner circumferential surface, and located between the fitting surface and the outer circumferential surface of the cage on the other side in the axial direction of the outer ring raceway, and the radial gap between the inner circumferential surface of the grease member and the outer circumferential surface of the cage is smaller than the radial gap between the guide surface and the outer circumferential surface of the cage. [Effects of the Invention]

[0009] According to this disclosure, it is possible to suppress abnormal noise from the ball bearing caused by the runout of the cage. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view of a ball bearing according to an embodiment. [Figure 2] Figure 2 is a magnified view of a portion of the ball bearing shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram illustrating the grease component. [Figure 4] Figure 4 is a schematic diagram of a portion of the retainer viewed from the radially outer side. [Figure 5]Figure 5 is a partially enlarged view of a ball bearing according to a modified example. [Figure 6] Figure 6 is a partially enlarged view of a ball bearing according to a modified example. [Modes for carrying out the invention]

[0011] <Summary of the embodiments of this disclosure> The embodiments of this disclosure are outlined below.

[0012] (1) The ball bearing of the present disclosure comprises an inner ring, an outer ring, a plurality of balls rotatably provided between the inner ring and the outer ring, a cage that holds the plurality of balls from both sides in the axial direction, and an annular grease member, wherein the inner circumferential surface of the outer ring includes an outer ring raceway on which the balls roll, a guide surface that guides the cage on one side in the axial direction of the outer ring raceway, and a fitting surface on the other side in the axial direction of the outer ring raceway against which the outer circumferential surface of the grease member abuts, wherein the grease member is entirely or at least on its inner circumferential surface, is located between the fitting surface and the outer circumferential surface of the cage on the other side in the axial direction of the outer ring raceway, and the radial gap between the inner circumferential surface of the grease member and the outer circumferential surface of the cage is smaller than the radial gap between the guide surface and the outer circumferential surface of the cage.

[0013] Because the inner circumferential surface of the grease component is filled with grease, it has higher elasticity than the guide surface of the outer ring. Furthermore, because the radial gap between the inner circumferential surface and the outer circumferential surface of the cage is relatively narrow, the outer circumferential surface of the cage contacts the inner circumferential surface before the guide surface. As a result, the inner circumferential surface absorbs the impact when it contacts the cage through elastic deformation, thereby reducing shock and vibration through a damping effect. Consequently, contact noise from the cage can be suppressed compared to when the cage contacts the guide surface, and abnormal noise from the ball bearing caused by cage runout can be suppressed.

[0014] (2) In the ball bearing described in (1) above, the consistency number of the grease contained in the grease member may be between No. 4 and No. 6.

[0015] By using a relatively hard grease in this way, the shape of the annular grease member can be maintained.

[0016] (3) In the ball bearing according to (1) or (2) above, the cage includes a first annular portion whose outer peripheral surface faces the guide surface in the radial direction, a second annular portion whose outer peripheral surface faces the inner peripheral surface of the grease member in the radial direction, a plurality of columns provided at predetermined intervals in the circumferential direction and connecting the first annular portion and the second annular portion in the axial direction, and grooves formed on the outer peripheral surfaces of the first annular portion, the columns, and the second annular portion respectively, for guiding the oil component of the grease adhered when the second annular portion contacts the grease member from the second annular portion to the first annular portion through the columns.

[0017] By forming grooves in the cage, the supply of the oil component to the entire outer peripheral surface of the cage can be promoted.

[0018] (4) In the ball bearing according to (1) to (3) above, the fitting surface may be a surface formed by turning, and the guide surface may be a surface formed by polishing.

[0019] By forming the fitting surface by turning, the fitting surface becomes a turned surface with many irregularities on the surface, and the grease member can be more reliably held on the fitting surface by the frictional force. Also, by forming the guide surface by polishing, the guide surface becomes a polished surface with few irregularities on the surface, and the outer peripheral surface of the cage can be guided with relatively small friction.

[0020] (5) In the ball bearing according to (1) to (4) above, the outer peripheral surface of the cage on the other axial side than the outer ring raceway is an inclined surface that inclines radially inward as it goes to the other axial side, and the inner peripheral surface of the grease member faces parallel to the inclined surface.

[0021] Due to the inclination of the inclined surface, when the retainer rotates in the circumferential direction, centrifugal force is applied to the grease adhering to the inclined surface in one axial direction. Therefore, when the inclined surface and the inner circumferential surface of the grease member come into contact, the oil from the grease adhering to the inclined surface is more easily moved axially to one side of the inclined surface, promoting the sharing of oil across the entire outer surface of the retainer. Furthermore, since the inclined surface and the inner circumferential surface of the grease member face each other parallel to one another, the inclined surface comes into contact with the inner circumferential surface over a relatively large area. Therefore, the contact pressure per unit area on the inner circumferential surface is reduced, and the impact is relatively reduced, thus suppressing contact noise.

[0022] (6) In the ball bearings described in (1) to (5) above, the inner circumferential surface of the outer ring may include a stepped portion formed between the outer ring raceway and the fitting surface, and the stepped portion may contact the surface of the grease member on one axial side, thereby restricting the movement of the grease member on one axial side.

[0023] The grease material physically catches on the stepped portion, which helps to suppress axial displacement of the grease material.

[0024] <Details of the embodiments of this disclosure> The embodiments of this disclosure will be described in detail below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0025] [Overall configuration of a ball bearing] Figure 1 is a cross-sectional view of a ball bearing 10 according to an embodiment. The ball bearing 10 illustrated in Figure 1 is an angular contact ball bearing used for spindle support in machine tools such as machining centers and NC lathes. However, the use of the ball bearing 10 is not limited to machine tools; it may also be used in vehicles, etc. Furthermore, the type of ball bearing 10 is not limited to an angular contact ball bearing; for example, a deep groove ball bearing (ball bearing) may also be used.

[0026] In this disclosure, the direction along the centerline C1 of the ball bearing 10 is the axial direction of the ball bearing 10, and is simply referred to as the "axial direction." The axial direction also includes the direction parallel to the centerline C1 (the left and right directions in Figure 1). The left side of Figure 1 is defined as "one side" of the axial direction, and the right side of Figure 1 is defined as "the other side" of the axial direction. The direction perpendicular to the centerline C1 is the radial direction of the ball bearing 10, and is simply referred to as the "radial direction." The direction in which the ball bearing 10 (specifically, the inner ring 11) rotates around the centerline C1 is the circumferential direction of the ball bearing 10, and is simply referred to as the "circumferential direction."

[0027] Figure 2 is a partially enlarged view of the ball bearing 10 shown in Figure 1. The ball bearing 10 comprises an inner ring 11, an outer ring 12, a plurality of balls 13, a cage 14, and a grease member 15. The inner ring 11, the outer ring 12, and the plurality of balls 13 are each formed from a metallic material such as high-carbon chromium bearing steel. The ball bearing 10 is an inner ring rotating type bearing in which the inner ring 11 is a rotating ring and the outer ring 12 is a stationary ring.

[0028] The inner ring 11 is an annular member that is fitted and fixed to the shaft S1. The shaft S1 is, for example, the spindle of a machine tool. The outer circumferential surface 11a of the inner ring 11 includes an arc-shaped inner ring raceway (raceway groove) 11b on which the balls 13 roll.

[0029] The outer ring 12 is a component that is fitted and fixed inside the housing H1. The inner circumferential surface 12a of the outer ring 12 includes an outer ring raceway 12b, a guide surface 12c, and a fitting surface 12d. The outer ring raceway 12b is a substantially arc-shaped raceway groove on which the ball 13 rolls. A shoulder portion 121 is formed on one axial side of the outer ring raceway 12b. In contrast, a counterbore 122 (counter-bored) is formed on the other axial side of the outer ring raceway 12b, where the shoulder portion has been removed to make it flat. Therefore, the inner diameter of the counterbore 122 is larger than the inner diameter of the shoulder portion 121.

[0030] The guide surface 12c is a flat surface formed on one axial side of the outer ring raceway 12b, and it guides the cage 14 by contacting the outer circumferential surface 14a of the cage 14, which is radially rubbing. When the cage 14 is positioned on the design raceway, the outer circumferential surface 14a faces the guide surface 12c with a radial gap G2 between them. Also, when the radial runout of the cage 14 from the design raceway is less than the gap G2, the guide surface 12c and the outer circumferential surface 14a do not come into contact.

[0031] During the rotational operation of the ball bearing 10, the cage 14 rotates while vibrating radially. When the amount of vibration exceeds the clearance G2, the outer circumferential surface 14a comes into contact with the guide surface 12c, restricting the radial vibration of the cage 14. Specifically, the outer circumferential surface 14a, which rotates circumferentially, comes into radial contact with the guide surface 12c and also slides against it circumferentially. In this way, the ball bearing 10 is an outer ring guided ball bearing in which the cage 14 is guided by the outer ring 12.

[0032] Furthermore, if the outer peripheral surface 14a, described later, contacts the grease member 15 first, the vibration of the retainer 14 is restricted by contact with the grease member 15, and therefore the retainer 14 does not contact the guide surface 12c.

[0033] The mating surface 12d is a flat surface formed on the other axial side of the outer ring raceway 12b, specifically formed on the counterbore 122. The mating surface 12d is the surface that the outer circumferential surface 15a of the grease member 15 abuts against, thereby fitting and fixing the grease member 15 inside.

[0034] Here, the inner circumferential surface 12a of the outer ring 12 is formed entirely by turning, and then the outer ring raceway 12b and guide surface 12c are formed by grinding. As a result, the outer ring raceway 12b and guide surface 12c become polished surfaces with few irregularities, allowing the ball 13 and the outer circumferential surface 14a of the retainer 14 to be guided with relatively little friction.

[0035] On the other hand, the mating surface 12d is a turned surface with more irregularities on its surface than, for example, the guide surface 12c. As a result, the friction between the mating surface 12d and the outer peripheral surface 15a of the grease member 15 is greater than when the mating surface 12d is a polished surface. This suppresses axial displacement of the grease member 15, and allows the grease member 15 to be held more securely by the mating surface 12d.

[0036] Multiple balls 13 are arranged circumferentially between the inner ring raceway 11b and the outer ring raceway 12b. When the inner ring 11 rotates circumferentially with the shaft S1, the multiple balls 13 roll between these two raceways 11b and 12b. The multiple balls 13 also contact both raceways 11b and 12b at a predetermined contact angle and receive both axial and radial loads applied from the shaft S1 and the like.

[0037] The grease member 15 is an annular member located radially between the outer ring 12 and the retainer 14, on the axial side of the outer ring raceway 12b. The outer circumferential surface 15a of the grease member 15 abuts against the fitting surface 12d, thereby fitting it to the outer ring 12.

[0038] Furthermore, in order to avoid interference with the ball 13, the grease member 15 is provided at the same position in the axial direction as one end of the second annular portion 142 that forms part of the pocket P1 (Figure 4) of the retainer 14, or at the other end in the axial direction.

[0039] Figure 3 is a schematic diagram illustrating the grease component 15. The grease member 15 is a member whose entire body is formed of grease 151, as shown in the cross-sectional view in Figure 3(a), for example. The grease 151 is made semi-solid or solid by dispersing a thickener in a raw material base oil. The "consistency number (Japanese Industrial Standard: JIS K2220)" of the grease 151 is between No. 4 and No. 6. By using such a relatively hard grease 151, the annular grease member 15 can be formed using only the grease 151. Furthermore, even if the grease member 15 includes a reinforcing member, as shown in Figures 3(b) and (c) described later, the shape of the grease member 15 can be maintained to some extent by using hard grease 151.

[0040] The grease member 15 may also include a reinforcing member in addition to the grease 151. For example, as shown in the cross-sectional view in Figure 3(b), the grease member 15 may have a reinforcing member 152 built inside, with the grease 151 enclosing the outer circumference of the reinforcing member 152. Alternatively, as shown in the cross-sectional view in Figure 3(c), the outer circumferential surface 15a of the grease member 15 may be formed by a reinforcing member 153, and the inner circumferential surface 15b may be formed by grease 151. In all of these variations from (a) to (c), the inner circumferential surface 15b of the grease member 15 is formed by grease 151.

[0041] Here, the reinforcing members 152 and 153 are members for maintaining the annular shape of the grease member 15, and are, for example, members having a hardness equal to or greater than that of the grease 151. The reinforcing members 152 and 153 are formed from, for example, the same synthetic resin material as the retainer 14. Note that when the grease member 15 includes the reinforcing members 152 and 153, it is not necessary to maintain the annular shape with the grease 151 alone, so the consistency number of the grease 151 may be less than No. 4, for example, No. 3.

[0042] Refer to Fig. 2. The inner peripheral surface 15b of the grease member 15 is a surface that guides the cage 14 by contacting the outer peripheral surface 14a of the cage 14 that swings in the radial direction. When the cage 14 is located on the design track, the outer peripheral surface 14a faces the inner peripheral surface 15b with a radial gap G1 therebetween. When the radial swing amount of the cage 14 is less than the gap G1, the inner peripheral surface 15b and the outer peripheral surface 14a do not contact each other.

[0043] During the rotation of the ball bearing 10, when the cage 14 rotates while swinging in the radial direction and the swing amount becomes equal to or greater than the gap G1, the outer peripheral surface 14a contacts the inner peripheral surface 15b, and the radial swing of the cage 14 is restricted. Specifically, the outer peripheral surface 14a that rotates in the circumferential direction contacts the inner peripheral surface 15b in the radial direction and also makes a sliding contact in the circumferential direction.

[0044] Here, the radial gap G1 is smaller than the radial gap G2 (G1 < G2). Therefore, when the cage 14 swings in the radial direction, the outer peripheral surface 14a of the cage 14 contacts the inner peripheral surface 15b of the grease member 15 prior to contacting the guide surface 12c of the outer ring 12.

[0045] The guide surface 12c is formed of metal as described above, while the inner peripheral surface 15b is formed of grease 151. The elasticity of the inner peripheral surface 15b is higher than that of the guide surface 12c. When the inner peripheral surface 15b contacts the cage 14, it receives the impact by elastic deformation, thereby reducing the impact and vibration by the damper effect. As a result, the contact noise of the cage 14 can be suppressed more effectively than when the cage 14 contacts the guide surface 12c.

[0046] Furthermore, the grease 151 is more elastic and softer than the cage 14. Therefore, it can more reliably absorb the impact when it comes into contact with the cage 14. On the other hand, if a material softer than the cage 14 is used as a guide, that material may wear down due to contact with the cage 14 and become debris inside the ball bearing 10. However, in this embodiment, since grease 151 is used as the soft material, even if the grease 151 wears down due to contact with the cage 14, the grease 151 has the function of lubricating the inside of the ball bearing 10, thus contributing to the suppression of oil depletion in the ball bearing 10, and thus reducing the generation of debris compared to when other materials are used.

[0047] In this way, the ball bearing 10 is provided with a grease member 15, and by temporarily bringing the radially vibrating cage 14 into contact with the inner circumferential surface 15b of the grease member 15, it is possible to suppress abnormal noise from the ball bearing 10 caused by the vibration of the cage 14.

[0048] Figure 4 is a schematic view of a portion of the retainer 14 as seen from the radially outer side. The retainer 14 is an annular member that holds multiple balls 13 from both sides in the axial direction with a predetermined spacing between them in the circumferential direction. In other words, the retainer 14 is a double-supported retainer. The retainer 14 is manufactured, for example, by injection molding of a synthetic resin material such as polyamide resin or polyetheretherketone (PEEK).

[0049] The retainer 14 includes a first annular portion 141, a second annular portion 142, a plurality of columnar portions 143, and a groove portion 144. The first annular portion 141 is an annular region whose outer circumferential surface 14a faces the guide surface 12c in the radial direction. The first annular portion 141 holds the ball 13 from one side in the axial direction. The portion of the outer circumferential surface 14a of the retainer 14 that corresponds to the first annular portion 141 is a surface parallel to the axial direction. When the retainer 14 is in the design track, the first annular portion 141 faces the guide surface 12c in parallel with a radial gap G2 between them.

[0050] The second annular portion 142 is an annular region whose outer circumferential surface 14a is radially opposite to the inner circumferential surface 15b of the grease member 15. The second annular portion 142 holds the ball 13 from the other axial side. The portion of the outer circumferential surface 14a of the retainer 14 that corresponds to the second annular portion 142 is a surface parallel to the axial direction. When the retainer 14 is in the design track, the second annular portion 142 is parallel to the inner circumferential surface 15b of the grease member 15 with a radial gap G1 between them.

[0051] In this manner, the second annular portion 142 and the inner circumferential surface 15b face each other parallel to one another. Therefore, when the retainer 14 vibrates radially, the second annular portion 142 contacts the inner circumferential surface 15b over a relatively large area. As a result, the contact pressure per unit area on the inner circumferential surface 15b is reduced, and the impact is relatively reduced, thus suppressing contact noise.

[0052] Multiple columnar sections 143 are provided at predetermined intervals in the circumferential direction and form a region that connects the first annular section 141 and the second annular section 142 in the axial direction. The multiple columnar sections 143 hold the ball 13 from the circumferential direction. Pockets P1 for accommodating the ball 13 are formed between the first annular section 141, the second annular section 142, and the multiple columnar sections 143. Multiple pockets P1 are formed at intervals in the circumferential direction.

[0053] The groove 144 is an axially extending groove (a recess radially inward) formed on the outer circumferential surface 14a of the first annular portion 141, the second annular portion 142, and the plurality of column portions 143. The groove 144 may be formed in a one-to-one ratio with all the column portions 143 as shown in Figure 4, or it may be formed only at a specific location among all the column portions 143, or at a number of locations less than the number of column portions 143.

[0054] The groove 144 guides the oil (base oil) of the grease 151 that adheres to the second annular portion 142 when it comes into contact with the grease member 15, from the second annular portion 142 to the first annular portion 141 via the column portion 143. The oil of the grease 151 is guided to the first annular portion 141 by capillary action, for example, through the groove 144, as well as by centrifugal force associated with the rotation of the retainer 14.

[0055] The oil from the grease 151 that has seeped into the groove 144 will spread over time to wet the outer surface 14a of the retainer 14. In addition, the oil from the grease 151 in the groove 144 may also be spread to the outer surface 14a of the retainer 14 by contact with, for example, the inner surface 15b or the guide surface 12c.

[0056] In this way, when the retainer 14 comes into contact with the grease member 15, the oil from the grease 151 is supplied to the outer circumferential surface 14a of the retainer 14. In particular, the formation of grooves 144 in the retainer 14 promotes the supply of oil to the entire outer circumferential surface 14a.

[0057] Thus, the grease member 15 has both the function of suppressing contact noise with the retainer 14 and the function of supplying oil to the retainer 14. In particular, the grease member 15 is softer than the retainer 14, and when it comes into contact with the retainer 14, the grease member 15 mainly undergoes elastic deformation, which suppresses abnormal noise. On the other hand, each time it comes into contact with the retainer 14, the grease 151 that forms the inner circumferential surface 15b of the grease member 15 is rubbed off and reduced, and the radial gap G1 widens compared to when it is not in use.

[0058] Furthermore, as the ball bearing 10 is used repeatedly, if the radial gap G1 widens to greater than or equal to the radial gap G2 (G1 ≥ G2), the radially vibrating cage 14 will come into contact with the guide surface 12c before the inner circumferential surface 15b. In this case as well, since the outer circumferential surface 14a of the cage 14 is supplied with grease 151 as described above, contact noise (stick-slip noise) caused by, for example, the outer circumferential friction of the outer circumferential surface 14a against the guide surface 12c can be suppressed.

[0059] As described above, the ball bearing 10 is configured such that, by providing a grease member 15, the cage 14 is guided by the grease member 15 for a certain period from the start of use of the ball bearing 10, and contact noise can be suppressed by absorbing the impact when the cage 14 comes into contact with the soft grease 151. After the ball bearing 10 has been used for a long period and the inner circumferential surface 15b of the grease member 15 has worn down to a certain extent, the cage 14 is guided by the guide surface 12c of the outer ring 12. At this point, the outer circumferential surface 14a of the cage 14 is moistened with oil supplied by the worn-down grease 151, so contact noise such as stick-slip noise can be suppressed compared to a normal outer ring guided ball bearing. In this way, the ball bearing 10 can suppress abnormal noise of the ball bearing 10 caused by the runout of the cage 14 for a longer period of time.

[0060] [Variation] The following describes modified examples of the embodiments. In the following modified examples, components identical to those in the embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0061] Figure 5 is a partially enlarged view of a modified ball bearing 10a. In the ball bearing 10 according to the above embodiment, the portion of the outer circumferential surface 14a of the cage 14 corresponding to the second annular portion 142 is a surface parallel to the axial direction. However, the present disclosure is not limited to this, and the portion may be an inclined surface 14b that is tilted with respect to the axial direction.

[0062] Specifically, in this modified example, the portion of the outer circumferential surface 14a of the retainer 14 corresponding to the second annular portion 142 is an inclined surface 14b that slopes radially inward as it is directed toward the other axial direction. Similarly, the inner circumferential surface 15b of the grease member 15 is also inclined radially inward as it is directed toward the other axial direction, and the inclined surface 14b and the inner circumferential surface 15b are parallel to each other.

[0063] In this case, the radial gap G1a between the outer surface 14a and the inner surface 15b refers to the radial gap of the outer surface 14a (or inner surface 15b), as shown in Figure 5.

[0064] Here, the radial clearance G1a is smaller than the radial clearance G2 (G1a < G2). Therefore, when the cage 14 swings radially, the outer peripheral surface 14a of the cage 14 contacts the inner peripheral surface 15b of the relatively soft grease member 15 prior to the guide surface 12c of the outer ring 12, thereby suppressing the contact noise.

[0065] Since the inclined surface 14b and the inner peripheral surface 15b face each other in parallel, the inclined surface 14b contacts the inner peripheral surface 15b over a relatively large area. For this reason, the contact pressure per unit area on the inner peripheral surface 15b is reduced, and the impact is relatively reduced, so that the contact noise can be suppressed.

[0066] Further, since the inclined surface 14b is inclined radially inward as it goes toward the other axial side, when the cage 14 rotates in the circumferential direction, a centrifugal force acting axially toward one side is applied to the grease 151 adhering to the inclined surface 14b. For this reason, when the inclined surface 14b and the inner peripheral surface 15b come into contact, the oil content of the grease 151 adhering to the inclined surface 14b is more likely to move axially toward one side of the inclined surface 14b, and the sharing of the oil content over the entire outer peripheral surface 14a of the cage 14 can be promoted.

[0067] FIG. 6 is a partially enlarged view of the ball bearing 10b according to a modified example. In the ball bearing 10 according to the above-described embodiment, the fitting surface 12d is a surface that connects flatly to the outer ring raceway 12b, and suppresses the axial displacement of the grease member 15 by frictional force. However, the implementation of the present disclosure is not limited to this, and the inner peripheral surface 12a of the outer ring 12 may further include a stepped portion 12e, and the axial displacement of the grease member 15 may be suppressed by this stepped portion 12e.

[0068] The stepped portion 12e is formed on the inner circumferential surface 12a of the outer ring 12, between the outer ring raceway 12b and the fitting surface 12d. With respect to the stepped portion 12e, the inner diameter on the other axial side of the inner circumferential surface 12a is larger than the inner diameter on one axial side of the stepped portion 12e, resulting in a step difference on the inner circumferential surface 12a at the stepped portion 12e. The stepped portion 12e may be a vertical step extending parallel to the radial direction, as shown in Figure 6, or it may be a slope-shaped step (incline) that is inclined in the axial direction.

[0069] The grease member 15 has its outer peripheral surface 15a in contact with the fitting surface 12d, and its axial side surface 15c is in contact with the stepped portion 12e, thereby restricting its movement in the axial direction relative to the stepped portion 12e.

[0070] Thus, in this modified example, the inner diameter of the inner circumferential surface 12a of the outer ring 12 on one axial side of the stepped portion 12e is smaller than the outer diameter of the grease member 15, and the inner diameter of the inner circumferential surface 12a of the outer ring 12 on the other axial side of the stepped portion 12e (i.e., the inner diameter of the fitting surface 12d) is about the same as the outer diameter of the grease member 15 (in reality, it is slightly smaller than the outer diameter of the grease member 15 for fitting purposes). Therefore, not only friction from the fitting surface 12d, but also the physical grip of the grease member 15 on the stepped portion 12e can suppress axial displacement of the grease member 15.

[0071] In particular, if the grease member 15 interferes with the ball 13, the ball 13 may be supplied with more grease 151 than necessary, which may increase the rolling resistance of the ball 13. In this modified example, the stepped portion 12e can more reliably prevent the grease member 15 from moving axially to one side of the stepped portion 12e. For example, by positioning the stepped portion 12e axially to the other end of the ball 13 on the other axial side, interference between the grease member 15 and the ball 13 can be prevented.

[0072] The stepped portion 12e is not limited to the shape shown in Figure 6, and may, for example, be a projection that partially protrudes radially inward between the outer ring raceway 12b and the mating surface 12d. In this case as well, the stepped portion 12e can have the function of restricting the axial movement of the grease member 15 by contacting the side surface 15c of the grease member 15.

[0073] [Note] The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of this disclosure is not limited to the embodiments and variations described above, but includes all modifications within the scope of equivalence to the configurations described in the claims. [Explanation of Symbols]

[0074] 10, 10a, 10b Ball bearing 11 Inner ring 11a Outer surface 11b Inner ring raceway 12 Outer ring 12a Inner surface 12b Outer ring raceway 12c Guide surface 12d Fitting surface 12e Step section 121 Shoulder section 122 Counterbore 13 Ball 14 Cage 14a Outer surface 14b Inclined surface 141 First ring section 142 Second ring section 143 Column section 144 Groove section 15 Grease member 15a Outer surface 15b Inner surface 15c Side surface 151 Grease 152,153 Reinforcement member C1 Centerline S1 Axis H1 Housing P1 pocket G1, G1a, G2 radial clearance

Claims

1. It comprises an inner ring, an outer ring, a plurality of balls that are rotatable between the inner ring and the outer ring, a retainer that holds the plurality of balls from both sides in the axial direction, and an annular grease member. The inner circumferential surface of the outer ring includes an outer ring raceway on which the balls roll, a guide surface that guides the retainer on one axial side of the outer ring raceway, and a fitting surface on the other axial side of the outer ring raceway against which the outer circumferential surface of the grease member abuts. The grease member is composed of grease on its entire or at least inner surface, and is located between the fitting surface and the outer surface of the retainer, on the other axial side of the outer ring raceway. The radial gap between the inner circumferential surface of the grease member and the outer circumferential surface of the retainer is smaller than the radial gap between the guide surface and the outer circumferential surface of the retainer. ball bearings.

2. The consistency number of the grease contained in the grease member is between No. 4 and No.

6. The ball bearing according to claim 1.

3. The aforementioned retainer is, The outer circumferential surface of the first annular portion is radially opposite to the guide surface, A second annular portion whose outer surface faces radially opposite the inner surface of the grease member, Multiple columnar portions are provided at predetermined intervals in the circumferential direction, connecting the first annular portion and the second annular portion in the axial direction. A groove is formed on the outer circumferential surface of the first annular portion, the column portion, and the second annular portion, which guides the oil from the grease that adheres to the second annular portion when the second annular portion comes into contact with the grease member from the second annular portion through the column portion to the first annular portion, including, The ball bearing according to claim 1 or claim 2.

4. The aforementioned mating surface is a surface formed by turning, The aforementioned guide surface is a surface formed by polishing. The ball bearing according to claim 1 or claim 2.

5. The outer circumferential surface of the retainer on the axial side other than the outer ring raceway is an inclined surface that slopes radially inward as it is directed toward the other axial side. The inner circumferential surface of the grease member is parallel to and opposite the inclined surface. The ball bearing according to claim 1 or claim 2.

6. The inner circumferential surface of the outer ring includes a stepped portion formed between the outer ring raceway and the fitting surface. The stepped portion abuts against the axial surface of the grease member, thereby restricting the axial movement of the grease member to one side. The ball bearing according to claim 1 or claim 2.

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