Jade Axle

Abstract

A ball bearing (10) in which, in a cross section including a center axis (C2), a first inferior angle (θ1) formed by a first inclined surface (23) and the center axis (C2) is smaller than a second inferior angle (θ2) formed by a second inclined surface (24) and the center axis (C2) and, in a cross section including a center axis (C1), when a second large circle (BC2) on a second side in the radial direction is a first end point (a, c), an intersection between a first straight line (L1) passing through a first large circle (BC1) on the first side in the radial direction and the second large circle (BC2) on the second side in the radial direction and a surface of a first imaginary torus (T1) on a first side in the radial direction is a second end point (b),the first inclined surface (23) on the first side in the radial direction closest to a second side in the axial direction is a third end point (d), and a point that is on the first inclined surface (23) on the first side in the radial direction and has the shortest distance from the first end point (a) is a fourth end point (e), the length of a first line segment (ab) is longer than the length of a second line segment (cd) or the length of the first line segment (ab) is shorter than the length of a second line segment (cd) and the length of the first line segment (ab) is shorter than the length of a third line segment (ce).

Description

[Technical Field]

[0001] The present disclosure relates to ball bearings. [Background technology]

[0002] Conventionally, there has been known a double-row angular contact ball bearing in which the minor angles between the bearing center axis and the line of action of each row of balls are in the same direction, and the pitch diameters of the ball sets in each row of balls are different, so that it can withstand a greater axial load than a single-row angular contact ball bearing. This type of ball bearing is called a tandem type.

[0003] FIG. 13 is a cross-sectional view of a conventional ball bearing. Conventional ball bearing 210 includes an inner ring assembly 235 and an outer ring 220. Inner ring assembly 235 includes an inner ring 230, a plurality of first balls 241, a plurality of second balls 242, a first cage 251, and a second cage 252. The diameters of the plurality of first balls 241 and the plurality of second balls 242 are the same. Inner ring 230 has, on its outer peripheral surface, a first inner ring raceway 231 on a first axial side and a second inner ring raceway 232 on a second axial side of first inner ring raceway 231. The raceway contact diameter of first inner ring raceway 231 is smaller than the raceway contact diameter of second inner ring raceway 232. The plurality of first balls 241 are rotatably arranged in first inner ring raceway 231. The first cage 251 has a plurality of pockets. The plurality of first balls 241 are slidably arranged in the plurality of pockets of the first cage 251. The diameter of the inscribed circle of the radially outer openings of the plurality of pockets of the first cage 251 is smaller than the diameter of the first balls 241. Therefore, when the plurality of first balls 241 are arranged in each pocket of the first cage 251 and then arranged in the first inner ring raceway 231, the inner ring 230, the plurality of first balls 241, and the first cage 251 do not separate. The plurality of second balls 242 are rollably arranged in the second inner ring raceway 232. The second cage 252 has a plurality of pockets. The plurality of second balls 242 are slidably arranged in the plurality of pockets of the second cage 252. The diameter of the inscribed circle of the radially outer openings of the multiple pockets of the second cage 252 is smaller than the diameter of the second balls 242, so when the multiple second balls 242 are placed in each pocket of the second cage 252 and arranged in the second inner ring raceway 232, the inner ring 230, the multiple second balls 242, and the second cage 252 do not separate. The inner ring assembly 235 is assembled so that the inner ring 230, the multiple first balls 241, the multiple second balls 242, the first cage 251, and the second cage 252 do not separate. The pitch diameter of the ball set in the row of first balls 241 formed by the multiple first balls 241 of the inner ring assembly 235 is smaller than the pitch diameter of the ball set in the row of second balls 242 formed by the multiple second balls 242.

[0004] The outer ring 220 has, on its inner circumferential surface, a first outer ring raceway 221 on a first axial side and a second outer ring raceway 222 on a second axial side of the first outer ring raceway 221. The raceway contact diameter of the first outer ring raceway 221 is smaller than the raceway contact diameter of the second outer ring raceway 222. The ball bearing 210 is formed by combining an inner ring assembly 235 and the outer ring 220.

[0005] In the ball bearing 210, a plurality of first balls 241 are rollably arranged in the first outer ring raceway 221, and a plurality of second balls 242 are rollably arranged in the second outer ring raceway 222. The nominal contact point of the first inner ring raceway 231 is located on the second axial side of the nominal contact point of the first outer ring raceway 221. The nominal contact point of the second inner ring raceway 232 is located on the second axial side of the nominal contact point of the second outer ring raceway 222. Therefore, the side surface on the first axial side of the inner ring 230 is the front surface of the inner ring 230, and the side surface on the second axial side is the back surface of the inner ring 230. Furthermore, the side surface on the first axial side of the outer ring 220 is the back surface of the outer ring 220, and the side surface on the second axial side is the front surface of the outer ring 220. Since ball bearing 210 has two rows of balls, the axial load that ball bearing 210 can bear is greater than the axial load that a single-row angular contact ball bearing can bear (see, for example, Patent Document 1).

[0006] On the other hand, in conventional ball bearing 210, the diameter of first balls 241 is the same as the diameter of second balls 242. In this case, the lifespan of the row of first balls 241, first inner ring raceway 231, and first outer ring raceway 221 may differ significantly from the lifespan of the row of second balls 242, second inner ring raceway 232, and second outer ring raceway 222. By making the diameter of the plurality of first balls 241 in conventional ball bearing 210 smaller than the diameter of the plurality of second balls 242, it is possible to reduce the difference in lifespan between the row of first balls 241 and the row of second balls 242, and it becomes possible to optimize the lifespan, rigidity, torque, etc. of ball bearing 210. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-194244 Summary of the Invention

[0008] The ball bearing of the present disclosure comprises an inner ring assembly and an outer ring, the inner ring assembly comprising an inner ring, a plurality of first balls, a plurality of second balls, a first cage, and a second cage, the inner ring having on its outer peripheral surface a first inner ring raceway on a first axial side and a second inner ring raceway on a second axial side of the first inner ring raceway, the raceway contact diameter of the first inner ring raceway being smaller than the raceway contact diameter of the second inner ring raceway, the plurality of first balls being rollably disposed in the first inner ring raceway, the first cage having a plurality of first pockets, and the plurality of first balls being the plurality of second balls are slidably disposed in first pockets, the plurality of second balls are rollably disposed in the second inner ring raceway, the second cage has a plurality of second pockets, the plurality of second balls are slidably disposed in the second pockets, the inner ring, the plurality of first balls, the plurality of second balls, the first cage, and the second cage are configured so as not to separate, and the pitch diameter of the ball set of the first ball row formed by the plurality of first balls of the inner ring assembly is smaller than the pitch diameter of the ball set of the second ball row formed by the plurality of second balls, The outer ring has, on its inner peripheral surface, a first outer ring raceway, a first inclined surface, a second inclined surface, and a second outer ring raceway, from a first side to a second side in the axial direction, and the inner peripheral surface of the outer ring expands without reducing in diameter from the first outer ring raceway to the second outer ring raceway, the raceway contact diameter of the first outer ring raceway is smaller than the raceway contact diameter of the second outer ring raceway, the diameters of the plurality of first balls are smaller than the diameters of the plurality of second balls, the plurality of first balls are disposed rollably in the first outer ring raceway, and the plurality of second balls are disposed rollably in the second outer ring raceway. a nominal contact point of the first inner ring raceway is located on a second axial side of a nominal contact point of the first outer ring raceway, a nominal contact point of the second inner ring raceway is located on a second axial side of a nominal contact point of the second outer ring raceway, the first inclined surface is formed on the inner peripheral surface of the outer ring on the second axial side of the first outer ring raceway and is an inclined surface whose diameter increases from the first axial side toward the second side, and the second inclined surface is formed on the inner peripheral surface of the outer ring on the second axial side of the first inclined surface and on the first axial side of the second outer ring raceway,The inclined surface has a diameter that increases from a first side toward a second side in the axial direction, and a first minor angle formed by the first inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring is smaller than a second minor angle formed by the second inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring, and when the plurality of first balls are arranged in the first inner ring raceway and are in contact with each other, the center of each of the plurality of first balls is on a first great circle, and half of the diameter of the first ball is equal to a first minor half, which is the radius of a first small circle. a first virtual torus is defined as a torus having a first major radius, which is the radius of the first great circle, and a second minor radius, which is the radius of the second small circle, which is half the diameter of the second ball, and a second major radius, which is the radius of the second small circle, which is half the pitch diameter of the ball set in the second row of balls, when the plurality of second balls are arranged in the second inner ring raceway and are in contact with each other; a second virtual torus is defined as a torus having a second major radius, which is the radius of the second great circle, which is half the pitch diameter of the ball set in the second row of balls; In a cross section including the bearing central axis, a first radial side and a second radial side that are 180° opposite to the first radial side in the circumferential direction are defined, the second great circle on the second radial side is defined as a first end point, the intersection of a line passing through the first great circle on the first radial side and the second great circle on the second radial side and the surface of the first radial side of the first virtual torus on the first radial side is defined as a second end point, a line segment connecting the first end point and the second end point is defined as a first line segment, and the first radial side the point on the first inclined surface on the radial first side closest to the second end point in the axial direction is defined as a third end point, the line segment connecting the first end point and the third end point is defined as a second line segment, the point on the first inclined surface on the radial first side closest to the first end point is defined as a fourth end point, the line segment connecting the first end point and the fourth end point is defined as a third line segment, and the length of the first line segment is greater than the length of the second line segment, or the length of the first line segment is smaller than the length of the second line segment and also smaller than the length of the third line segment.

[0009] In the ball bearing disclosed herein, the outer ring has, on its inner circumferential surface, from a first side to a second side in the axial direction, the first outer ring raceway, the first inclined surface, the second inclined surface, the second outer ring raceway, and a third inclined surface, the inner circumferential surface of the outer ring expands from the first outer ring raceway to the third inclined surface without reducing in diameter, and the first minor angle is smaller than the third minor angle formed by the third inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring.

[0010] In the ball bearing of the present disclosure, the plurality of second balls and an imaginary plane that includes a front surface on the second axial side of the outer ring and is perpendicular to the center axis of the outer ring overlap in the axial direction. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing the overall configuration of a ball bearing according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an inner ring assembly. [Figure 3] FIG. 2 is a schematic diagram showing an outline of a first virtual torus and a second virtual torus. [Figure 4] FIG. 2 is a cross-sectional view showing the outer ring according to the first embodiment. [Figure 5] FIG. 4 is a cross-sectional view showing inclined surfaces formed on the inner peripheral surface of the outer ring. [Figure 6] 3 is a cross-sectional view showing the state in which the outer ring is assembled to the inner ring assembly of the ball bearing according to the first embodiment. FIG. [Figure 7] FIG. 6 is a cross-sectional view showing the overall configuration of a ball bearing according to a second embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing an outer ring according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing the state in which the outer ring is assembled to the inner ring assembly of the ball bearing according to the second embodiment. [Figure 10] FIG. 2 is a cross-sectional view showing the overall configuration of a ball bearing according to a comparative example. [Figure 11] FIG. 10 is a cross-sectional view showing an outer ring according to a comparative example. [Figure 12]FIG. 10 is a cross-sectional view showing the state in which an outer ring is assembled to an inner ring assembly of a ball bearing according to a comparative example. [Figure 13] FIG. 1 is a cross-sectional view showing a conventional ball bearing. [Figure 14] FIG. 10 is a cross-sectional view showing the state in which the outer ring is assembled to the inner ring assembly in the ball bearing of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Problems to be Solved by the Invention of the Present Disclosure> Fig. 14 is a cross-sectional view showing the assembly of the outer ring to the inner ring assembly in a comparative ball bearing. The double-row ball bearing in Fig. 14 is configured such that the second balls 242 of the conventional double-row ball bearing 210 shown in Fig. 13 are larger than the first balls 241, thereby optimizing the life, rigidity, torque, etc. of the ball bearing 210. The comparative double-row ball bearing 110 includes an inner ring assembly 135 and an outer ring 120. The inner ring assembly 135 includes an inner ring 130, a plurality of first balls 141, a plurality of second balls 142, a first cage 151, and a second cage 152. The inner ring 130 has, on its outer peripheral surface, a first inner ring raceway 131 on a first axial side and a second inner ring raceway 132 on a second axial side of the first inner ring raceway 131. The raceway contact diameter of the first inner ring raceway 131 is smaller than the raceway contact diameter of the second inner ring raceway 132. A plurality of first balls 141 are rollably arranged in the first inner ring raceway 131. The first cage 151 has a plurality of pockets. The plurality of first balls 141 are slidably arranged in the plurality of pockets of the first cage 151. Because the diameter of the inscribed circle of the radially outer openings of the plurality of pockets of the first cage 151 is smaller than the diameter of the first balls 141, when the plurality of first balls 141 are respectively arranged in each pocket of the first cage 151 and arranged in the first inner ring raceway 131, the inner ring 130, the plurality of first balls 141, and the first cage 151 do not separate. A plurality of second balls 142 are rollably arranged in the second inner ring raceway 132. The second cage 152 has a plurality of pockets. The multiple second balls 142 are slidably arranged in multiple pockets of the second cage 152. The diameter of the inscribed circle of the radially outer openings of the multiple pockets of the second cage 152 is smaller than the diameter of the second balls 142. Therefore, when the multiple second balls 142 are arranged in each pocket of the second cage 152 and then arranged in the second inner ring raceway 132, the inner ring 130, the multiple second balls 142, and the second cage 152 do not separate. In this way, the inner ring 130, the multiple first balls 141, the multiple second balls 142, the first cage 151, and the second cage 152 are configured not to separate. The pitch diameter of the ball set of the row of first balls 141 formed by a plurality of first balls 141 of the inner ring assembly 135 is smaller than the pitch diameter of the ball set of the row of second balls 142 formed by a plurality of second balls 142.The diameter of the plurality of first balls 141 is smaller than the diameter of the plurality of second balls 142. The outer ring 120 has, on its inner circumferential surface, a first outer ring raceway 121, a first inclined surface 123, a second inclined surface 124, a second outer ring raceway 122, and a third inclined surface 125, from the first side to the second side in the axial direction. The inner circumferential surface of the outer ring 120 expands in diameter from the first outer ring raceway 121 to the third inclined surface 125 without reducing in diameter. The raceway contact diameter of the first outer ring raceway 121 is smaller than the raceway contact diameter of the second outer ring raceway 122. The ball bearing 110 is formed by combining an inner ring assembly 135 and an outer ring 120. The plurality of first balls 141 are rollably arranged in the first outer ring raceway 121. The plurality of second balls 142 are rollably arranged in the second outer ring raceway 122. The nominal contact point of the first inner ring raceway 131 is located on the second axial side of the nominal contact point of the first outer ring raceway 121. The nominal contact point of the second inner ring raceway 132 is located on the second axial side of the nominal contact point of the second outer ring raceway 122. The first inclined surface 123 is formed on the inner peripheral surface of the outer ring 120 on the second axial side of the first outer ring raceway 121, and is a conical surface whose diameter increases from the first axial side to the second side. The second inclined surface 124 is formed on the inner peripheral surface of the outer ring 120 on the second axial side of the first inclined surface 123, and on the first axial side of the second outer ring raceway 122, and is a conical surface whose diameter increases from the first axial side to the second side. The third inclined surface 125 is formed on the second axial side of the second outer ring raceway 122 on the inner peripheral surface of the outer ring 120, is adjacent to the front surface of the outer ring 120, and is a conical surface whose diameter increases from the first axial side toward the second axial side.

[0013] 14, in the ball bearing 110 having such a configuration, when assembling the outer ring 120 to the inner ring assembly 135, if the center axis C102 of the outer ring 120 is inclined with respect to the center axis C103 of the inner ring assembly 135, the first ball 141 is tightly pinched between the first inclined surface 123 and the first inner ring raceway 131, making contact and preventing the first ball 141 from sliding, which may result in a smooth assembly failure (the first ball 141 may stop in an inclined state and not be assembled). In such a case, if the outer ring 120 is forcibly pushed into the inner ring assembly 135, the first ball 141 may get caught in the outer ring 120, damaging the first ball 141.

[0014] The present disclosure aims to improve the ease of assembly of an outer ring to an inner ring assembly in a ball bearing, and to suppress damage to the ball bearing.

[0015] <Effects of the Invention of the Present Disclosure> According to the ball bearing of the present disclosure, the ease of assembling the outer ring to the inner ring assembly can be improved, and damage to the ball bearing can be suppressed.

[0016] <Summary of the embodiments of the presently disclosed invention> Below, an outline of the embodiments of the present disclosure will be listed and described.

[0017] (1) A ball bearing of the present disclosure comprises an inner ring assembly and an outer ring, the inner ring assembly comprising an inner ring, a plurality of first balls, a plurality of second balls, a first retainer, and a second retainer, the inner ring having, on its outer peripheral surface, a first inner ring raceway on a first axial side and a second inner ring raceway on a second axial side of the first inner ring raceway, the raceway contact diameter of the first inner ring raceway being smaller than the raceway contact diameter of the second inner ring raceway, the plurality of first balls being rollably disposed in the first inner ring raceway, the first retainer having a plurality of first pockets, and the plurality of first balls being The inner ring assembly has a plurality of first balls slidably disposed in the first pockets, the plurality of second balls are slidably disposed in the second pockets, the second cage has a plurality of second pockets, the plurality of second balls are slidably disposed in the second pockets, the inner ring, the plurality of first balls, the plurality of second balls, the first cage, and the second cage are configured so as not to separate, and the pitch diameter of the ball set of the first ball row formed by the plurality of first balls of the inner ring assembly is smaller than the pitch diameter of the ball set of the second ball row formed by the plurality of second balls. The outer ring has, on its inner peripheral surface, a first outer ring raceway, a first inclined surface, a second inclined surface, and a second outer ring raceway, from a first side to a second side in the axial direction, the inner peripheral surface of the outer ring expands without reducing in diameter from the first outer ring raceway to the second outer ring raceway, the raceway contact diameter of the first outer ring raceway is smaller than the raceway contact diameter of the second outer ring raceway, the diameters of the plurality of first balls are smaller than the diameters of the plurality of second balls, the plurality of first balls are rollably disposed in the first outer ring raceway, and the plurality of second balls are rollably disposed in the second outer ring raceway. a nominal contact point of the first inner ring raceway is located on a second axial side of a nominal contact point of the first outer ring raceway, a nominal contact point of the second inner ring raceway is located on a second axial side of a nominal contact point of the second outer ring raceway, the first inclined surface is formed on the inner peripheral surface of the outer ring on the second axial side of the first outer ring raceway and is an inclined surface whose diameter increases from the first axial side toward the second side, and the second inclined surface is formed on the inner peripheral surface of the outer ring on the second axial side of the first inclined surface and on the first axial side of the second outer ring raceway,The inclined surface has a diameter that increases from a first side toward a second side in the axial direction, and a first minor angle formed by the first inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring is smaller than a second minor angle formed by the second inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring, and when the plurality of first balls are arranged in the first inner ring raceway and are in contact with each other, the center of each of the plurality of first balls is on a first great circle, and half of the diameter of the first ball is equal to a first minor half, which is the radius of a first small circle. a first virtual torus is defined as a torus having a first major radius, which is the radius of the first great circle, and a second minor radius, which is the radius of the second small circle, which is half the diameter of the second ball, and a second major radius, which is the radius of the second great circle, which is half the pitch diameter of the ball set in the second row of balls, when the plurality of second balls are arranged in the second inner ring raceway and are in contact with each other; a second virtual torus is defined as a torus having a second major radius, which is the radius of the second great circle, which is half the diameter of the second ball, and a second minor radius, which is the radius of the second great circle, which is half the pitch diameter of the ball set in the second row of balls. In a cross section including the bearing central axis, a first radial side and a second radial side that are 180° opposite to the first radial side in the circumferential direction are defined, the second great circle on the second radial side is defined as a first end point, the intersection of a line passing through the first great circle on the first radial side and the second great circle on the second radial side and the surface of the first radial side of the first virtual torus on the first radial side is defined as a second end point, a line segment connecting the first end point and the second end point is defined as a first line segment, the point on the first inclined surface closest to the second axial side is defined as a third end point, the line segment connecting the first end point and the third end point is defined as a second line segment, the point on the first inclined surface on the first radial side that is the shortest distance from the first end point is defined as a fourth end point, the line segment connecting the first end point and the fourth end point is defined as a third line segment, and the length of the first line segment is greater than the length of the second line segment, or the length of the first line segment is smaller than the length of the second line segment and also smaller than the length of the third line segment.

[0018] In a ball bearing having such a configuration, the ease of assembling the outer ring to the inner ring assembly can be improved, and damage to the ball bearing can be suppressed.

[0019] (2) In the ball bearing of the present disclosure, preferably, the outer ring has, on its inner circumferential surface, from a first side to a second side in the axial direction, the first outer ring raceway, the first inclined surface, the second inclined surface, the second outer ring raceway, and a third inclined surface, the inner circumferential surface of the outer ring expands from the first outer ring raceway to the third inclined surface without reducing in diameter, and the first minor angle is smaller than a third minor angle formed by the third inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring.

[0020] (3) In the ball bearing of the present disclosure, the plurality of second balls preferably overlap in the axial direction with an imaginary plane that includes a front surface of the outer ring on the second axial side and is perpendicular to the center axis of the outer ring.

[0021] <Details of the embodiment of the present disclosure> Hereinafter, embodiments of the present disclosure will be described.

[0022] [About ball bearings] FIG. 1 is a cross-sectional view showing the overall configuration of a ball bearing according to a first embodiment. The ball bearing 10 shown in FIG. 1 is a double-row angular contact ball bearing. The minor angles between the bearing center axis and the line of action of each row of balls are in the same direction, and the pitch diameters of the ball sets in each row of balls are different. This ball bearing can withstand a larger axial load than a single-row angular contact ball bearing. This type of ball bearing is called a tandem type. The ball bearing 10 is used, for example, to support a pinion shaft constituting a differential mechanism (gear mechanism), which is a bearing device used in a differential gear device mounted on an automobile or the like, so that it can rotate freely relative to the case. The ball bearing 10 includes an inner ring assembly 35 and an outer ring 20. In the following description, the center axis of the ball bearing 10 is referred to as center axis C1. Similarly, the center axis of the outer ring 20 is referred to as center axis C2, and the center axis of the inner ring 30 is referred to as center axis C3. The center axis C2 of the outer ring 20 and the center axis C3 of the inner ring 30 coincide with the center axis C1 of the ball bearing 10 when the inner ring assembly 35 and the outer ring 20 are combined. In the following description, one direction along the center axis C1 of the ball bearing 10 will be referred to as the first axial side, and the direction 180° opposite from the first axial side along the center axis of the ball bearing 10 will be referred to as the second axial side. Also, in the following description, in a cross section including the center axis C1 of the ball bearing 10, one direction perpendicular to the center axis C1 will be referred to as the first radial side, and the direction 180° opposite from the first radial side perpendicular to the center axis C1 will be referred to as the second radial side.

[0023] (inner ring assembly) 2 is a cross-sectional view showing an inner ring assembly 35. The inner ring assembly 35 includes an inner ring 30, a plurality of first balls 41, a plurality of second balls 42, a first cage 51, and a second cage 52.

[0024] The inner ring 30 shown in FIG. 2 is made of steel, such as high-carbon chromium bearing steel, carbon steel, or alloy steel. The inner ring 30 is cylindrical. From the first axial side to the second axial side, the inner ring 30 has a first shoulder, a first inner ring raceway 31, a second shoulder, a second inner ring raceway 32, and a third shoulder on its outer circumferential surface. The first shoulder has a cylindrical outer circumferential surface. The first inner ring raceway 31 is a raceway groove with a groove radius slightly larger than half the diameter of the first ball 41 (described later). The second shoulder has a conical outer circumferential surface whose diameter increases from the first axial side to the second axial side, followed by a cylindrical surface. The second inner ring raceway 32 is a raceway groove with a groove radius slightly larger than half the diameter of the second ball 42 (described later). The third shoulder has a cylindrical outer circumferential surface. The raceway contact diameter of the first inner ring raceway 31 is smaller than the raceway contact diameter of the second inner ring raceway 32. The diameter of the first shoulder is larger than the raceway contact diameter of the first inner ring raceway 31 and smaller than the diameter of the second shoulder. The diameter of the second shoulder is larger than the diameter of the second inner ring raceway 32 and smaller than the diameter of the third shoulder. The first ball 41 is made of a steel material such as high carbon chromium bearing steel. The second ball 42 is made of a steel material such as high carbon chromium bearing steel. The diameter of the first ball 41 is smaller than the diameter of the second ball 42.

[0025] The first cage 51 is formed in an annular shape. The first cage 51 has a first annular body 51a, a second annular body 51b, and a plurality of first pillars 51c. The first annular body 51a is located on a first axial side of the plurality of first pillars 51c. The second annular body 51b is located on a second axial side of the plurality of first pillars 51c. The plurality of first pillars 51c are connected to the first annular body 51a on the second axial side of the first annular body 51a. The plurality of first pillars 51c are connected to the second annular body 51b on the first axial side of the second annular body 51b. The plurality of first pillars 51c are arranged at equal intervals around the circumferential direction of the first annular body 51a. The diameter of the outer peripheral surface of the first annular body 51a is smaller than the diameter of the outer peripheral surface of the second annular body 51b. The diameter of the inner peripheral surface of the first annular body 51a is smaller than the diameter of the inner peripheral surface of the second annular body 51b. The area surrounded by the first annular body 51a, the second annular body 51b, and the circumferentially adjacent first pillars 51c constitutes a plurality of first pockets 53 that hold the first balls 41. The diameter of the inscribed circle of the radially outer openings of the plurality of first pockets 53 of the first cage 51 is smaller than the diameter of the first balls 41. The first cage 51 is made of a synthetic resin such as polyamide resin, polyphenylene sulfide resin, or phenolic resin.

[0026] The second cage 52 is formed in an annular shape. The second cage 52 has a third annular body 52b, a fourth annular body 52a, and a plurality of second pillars 52c. The third annular body 52b is located on a first axial side of the plurality of second pillars 52c. The fourth annular body 52a is located on a second axial side of the plurality of second pillars 52c. The plurality of second pillars 52c are connected to the third annular body 52b on the second axial side of the third annular body 52b. The plurality of second pillars 52c are connected to the fourth annular body 52a on the first axial side of the fourth annular body 52a. The plurality of second pillars 52c are arranged at equal intervals around the circumferential direction of the third annular body 52b. The diameter of the outer peripheral surface of the third annular body 52b is smaller than the diameter of the outer peripheral surface of the fourth annular body 52a. The diameter of the inner peripheral surface of the third annular body 52b is smaller than the diameter of the inner peripheral surface of the fourth annular body 52a. The area surrounded by the third annular body 52b, the fourth annular body 52a, and the second pillars 52c adjacent to them in the circumferential direction forms multiple second pockets 54 that hold the second balls 42. The diameter of the inscribed circle of the radially outer openings of the multiple second pockets 54 of the second cage 52 is smaller than the diameter of the second balls 42. The second cage 52 is made of a synthetic resin such as polyamide resin, polyphenylene sulfide resin, or phenolic resin.

[0027] As shown in FIG. 2 , the plurality of first balls 41 constituting the row of first balls 41 are rollably arranged in the first inner ring raceway 31 of the inner ring 30. The plurality of first balls 41 are slidably arranged in a plurality of first pockets 53 of the first cage 51. A plurality of first pockets 53 are formed along the circumferential direction, thereby enabling the first cage 51 to hold the plurality of first balls 41 at equal intervals along the circumferential direction. The diameter of the inscribed circle of the radially outer openings of the plurality of first pockets 53 of the first cage 51 is smaller than the diameter of the first balls 41, so the first balls 41 do not fall out radially outward from the first pockets 53 of the first cage 51. In addition, the diameter of the cylindrical surface of the outer circumferential surface of the first shoulder is larger than the raceway contact diameter of the first inner ring raceway 31. Furthermore, the minimum diameter of the conical surface on the outer peripheral surface of the second shoulder is larger than the raceway contact diameter of the first inner ring raceway 31. Therefore, when the multiple first balls 41 are placed in the respective first pockets 53 of the first cage 51 and arranged in the first inner ring raceway 31, the inner ring 30, the multiple first balls 41, and the first cage 51 do not separate.

[0028] The second balls 42 constituting the row of second balls 42 are rollably arranged in the second inner ring raceway 32 of the inner ring 30. The second balls 42 are slidably arranged in a plurality of second pockets 54 of the second cage 52. A plurality of second pockets 54 are formed along the circumferential direction, thereby enabling the second cage 52 to hold the second balls 42 at equal intervals along the circumferential direction. The diameter of the inscribed circle of the radially outer openings of the second pockets 54 of the second cage 52 is smaller than the diameter of the second balls 42, so the second balls 42 do not fall out radially outward from the second pockets 54 of the second cage 52. The diameter of the cylindrical surface of the outer peripheral surface of the second shoulder is larger than the raceway contact diameter of the second inner ring raceway 32. The diameter of the cylindrical surface of the outer peripheral surface of the third shoulder is larger than the raceway contact diameter of the second inner ring raceway 32. Therefore, when the multiple second balls 42 are placed in the second pockets 54 of the second retainer 52 and arranged on the second inner ring raceway 32, the inner ring 30, the multiple second balls 42, and the second retainer 52 do not separate.

[0029] 2, the inner ring assembly 35 is configured so that the inner ring 30, the plurality of first balls 41, the plurality of second balls 42, the first cage 51, and the second cage 52 cannot be separated. In other words, the inner ring assembly 35 is the ball bearing 10 from which the outer ring 20 has been removed. The pitch diameter of the ball set in the row of first balls 41 of the inner ring assembly 35, which is made up of the plurality of first balls 41, is smaller than the pitch diameter of the ball set in the row of second balls 42, which is made up of the plurality of second balls 42.

[0030] 3, for convenience of explanation, a first imaginary torus T1 and a second imaginary torus T2 are defined. The first imaginary torus T1 is an imaginary three-dimensional shape representing the rolling region of a plurality of first balls 41 that are rollably arranged in the first inner ring raceway 31. The first imaginary torus T1 is defined as having a first minor radius Sr1, which is the radius of a first small circle SC1 that is the outline of a cross section including the center of each of the first balls 41 when each of the first balls 41 is arranged in and contacts the first inner ring raceway 31 after the inner ring assembly 35 and the outer ring 20 are assembled, and as a first major radius Br1, which is the radius of a first large circle BC1 that is an imaginary circle connecting the centers of each of the first balls 41. In other words, the first minor radius Sr1 is the radius of the first ball 41 and is half the diameter of the first ball 41, and the first major radius Br1 is half the pitch diameter of the ball set in the row of first balls 41 made up of multiple first balls 41. The center of each of the multiple first balls 41 is located on the first great circle BC1. Note that in this description, the first imaginary torus T1 is defined based on the first ball 41 arranged in the first inner ring raceway 31, but the first imaginary torus T1 may also be defined based on the first ball 41 when each first ball 41 is arranged in and in contact with the first outer ring raceway 21 after the inner ring assembly 35 and the outer ring 20 are assembled.

[0031] The second imaginary torus T2 is an imaginary three-dimensional shape representing the rolling region of the multiple second balls 42 rollably arranged in the second inner ring raceway 32. The second imaginary torus T2 is defined as having a second minor radius Sr2, which is the radius of a second small circle SC2 that is the outer shape of a cross section including the center of each of the second balls 42 when each of the second balls 42 is arranged in and contacts the second inner ring raceway 32 after the inner ring assembly 35 and the outer ring 20 are assembled, and a second major radius Br2, which is the radius of a second large circle BC2 that is an imaginary circle connecting the centers of each of the second balls 42. In other words, the second minor radius Sr2 is the radius of the second ball 42 and is half the diameter of the second ball 42, and the second major radius Br2 is half the pitch diameter of the ball set in the row of the second balls 42 that is made up of the multiple second balls 42. The center of each of the multiple second balls 42 is located on the second great circle BC2. In this description, the second imaginary torus T2 is defined based on the second balls 42 arranged in the second inner ring raceway 32, but the second imaginary torus T2 may also be defined based on the second balls 42 when each second ball 42 is arranged in and in contact with the second outer ring raceway 22 when the inner ring assembly 35 and the outer ring 20 are assembled.

[0032] 2, for convenience of explanation, a first straight line L1 is defined for the inner ring assembly 35. The first straight line L1 is a straight line that intersects the central axis C3, a first great circle BC1 on a first radial side, and a second great circle BC2 on a second radial side in a cross section that includes the central axis C3 of the inner ring 30. The first radial side is one radial direction in the cross section that includes the central axis C3 of the inner ring 30, and the second radial side is a radial direction that is 180° circumferentially opposite the first radial side about the central axis C3 of the inner ring 30 in the cross section that includes the central axis C3 of the inner ring 30.

[0033] As shown in FIG. 2, for the sake of convenience, points a and b are defined for the inner ring assembly 35. Point a (first endpoint) is the intersection of the first line L1 and the second great circle BC2 on the second radial side in a cross section including the central axis C3 of the inner ring 30. Point a (first endpoint) is the center of the second ball 42 when the center of the second ball 42 is shown on the cross section including the central axis C3. Point b (second endpoint) is the intersection of the first line L1 and the surface of the first radial side of the first virtual torus T1 on the first radial side in a cross section including the central axis C3 of the inner ring 30. In the following description, the line segment having point a (first endpoint) and point b (second endpoint) as its endpoints is referred to as the first line segment ab. The first line segment ab is a portion of the first line L1. In the circumferential direction of the inner ring assembly 35, the phases of points a and b are different by 180 degrees.

[0034] (Detailed shape of outer ring) FIG. 4 is a cross-sectional view showing an outer ring according to the first embodiment. FIG. 5 is a cross-sectional view showing the inclined surfaces formed on the inner peripheral surface of the outer ring 20. The outer ring 20 is made of a steel material such as high-carbon chromium bearing steel, carbon steel, or alloy steel. The outer ring 20 has, from the first axial side to the second axial side, a fourth shoulder, a first outer ring raceway 21, a first inclined surface 23, a second inclined surface 24, a second outer ring raceway 22, and a third inclined surface 25 on its inner peripheral surface. The inner peripheral surface of the outer ring 20 expands in diameter from the first outer ring raceway 21 to the third inclined surface 25 without reducing in diameter. The raceway contact diameter of the first outer ring raceway 21 is smaller than the raceway contact diameter of the second outer ring raceway 22.

[0035] The first inclined surface 23 is formed on the inner peripheral surface of the outer ring 20 on a second axial side of the first outer ring raceway 21, and is a conical surface whose diameter increases from the first axial side to the second axial side. The second inclined surface 24 is formed on the inner peripheral surface of the outer ring 20 on the second axial side of the first inclined surface 23, which is also on the first axial side of the second outer ring raceway 22, and is a conical surface whose diameter increases from the first axial side to the second axial side. The third inclined surface 25 is formed on the inner peripheral surface of the outer ring 20 on the second axial side of the second outer ring raceway 22, is adjacent to the front surface of the outer ring 20, and is a conical surface whose diameter increases from the first axial side to the second axial side. The axial length of the second inclined surface 24 is preferably 1 / 10 to 1 / 2 of the axial length of the first inclined surface 23. The axial length of the third inclined surface 25 is preferably 1 / 10 to 1 / 2 of the axial length of the first inclined surface 23 .

[0036] In a cross section including the central axis C2 of the outer ring 20, the first minor angle θ1 formed by the first inclined surface 23 and the central axis C2 of the outer ring 20 (in FIG. 5, a cylindrical surface centered on the central axis C2 of the outer ring 20) is smaller than the second minor angle θ2 formed by the second inclined surface 24 and the central axis C2 of the outer ring 20 (in FIG. 5, a cylindrical surface centered on the central axis C2 of the outer ring 20). In a cross section including the central axis C2 of the outer ring 20, the first minor angle θ1 is smaller than the third minor angle θ3 formed by the third inclined surface 25 and the central axis C2 of the outer ring 20 (in FIG. 5, a cylindrical surface centered on the central axis C2 of the outer ring 20). The first minor angle θ1 is preferably 12° or less. The second minor angle θ2 is preferably 25° or greater and 75° or less. The third minor angle θ3 is preferably 25° or greater and 75° or less.

[0037] As shown in FIG. 4, for the sake of convenience, a second straight line L2 is defined for the outer ring 20. In FIG. 4, a first imaginary torus T1 and a second imaginary torus T2 are arranged on the outer ring 20. The first imaginary torus T1 is arranged so that the centers of the multiple first balls 41 arranged in the first outer ring raceway 21 coincide with the first great circle BC1 when the inner ring assembly 35 and the outer ring 20 are assembled. The second imaginary torus T2 is arranged so that the centers of the multiple second balls 42 arranged in the second outer ring raceway 22 coincide with the second great circle BC2 when the inner ring assembly 35 and the outer ring 20 are assembled. The second straight line L2 is a straight line that intersects the central axis C2, the second great circle BC2 on the second radial side, and the second axially most extreme side of the first inclined surface 23 on the first radial side in a cross section including the central axis C2 of the outer ring 20.

[0038] As shown in FIG. 4, for the sake of convenience, points c and d are defined for the outer ring 20. Point c is the point where the second straight line L2 intersects with the second great circle BC2 (see FIG. 3) on the second radial side in a cross section including the central axis C2 of the outer ring 20. Point c is the center of the second ball 42 when the center of the second ball 42 is shown on a cross section including this central axis C2. Note that point c coincides with point a in a cross section including the central axis C1 (C2, C3) of the ball bearing 10. For this reason, point c, like point a, will be referred to as the "first end point" in this description. Point d (third end point) is the point where the second straight line L2 intersects with the first inclined surface 23 on the second radial side in the cross section including the central axis C2 of the outer ring 20. In the following description, the line segment having point c (first endpoint) and point d (third endpoint) as its endpoints will be referred to as the second line segment cd. The second line segment cd is a part of the second straight line L2. In the circumferential direction of the outer ring 20, the phases of points c and d are 180° apart. The phase of point c is the same as the phase of point a, and the phase of point d is the same as the phase of point b.

[0039] (Ball bearing according to the first embodiment) As shown in FIG. 1 , the ball bearing 10 is formed by combining an inner ring assembly 35 and an outer ring 20. A plurality of first balls 41 are rollably arranged in the first outer ring raceway 21. A plurality of second balls 42 are rollably arranged in the second outer ring raceway 22. The nominal contact point of the first inner ring raceway 31 is located on the second axial side of the nominal contact point of the first outer ring raceway 21. The nominal contact point of the second inner ring raceway 32 is located on the second axial side of the nominal contact point of the second outer ring raceway 22. The side surface on the first axial side of the inner ring 30 is the front surface of the inner ring 30, and the side surface on the second axial side of the inner ring 30 is the back surface of the inner ring 30. The side surface on the first axial side of the outer ring 20 is the back surface of the outer ring 20, and the side surface on the second axial side of the outer ring 20 is the front surface of the outer ring 20.

[0040] FIG. 6 is a cross-sectional view showing the assembly of the outer ring to the inner ring assembly of the ball bearing according to the first embodiment. FIG. 6 shows a first ball bearing 10A, which is the ball bearing 10 according to the first embodiment. The first ball bearing 10A has a first outer ring 20A, which is the outer ring 20 according to the first embodiment. In this description, the first outer ring raceway 21 of the first outer ring 20A will be referred to as the first outer ring raceway 21A, the second outer ring raceway 22 as the second outer ring raceway 22A, the first inclined surface 23 as the first inclined surface 23A, the second inclined surface 24 as the second inclined surface 24A, and the third inclined surface 25 as the third inclined surface 25A. In this description, the first ball bearing 10A will also be simply referred to as the ball bearing 10A, and the first outer ring 20A as the outer ring 20A.

[0041] In the first ball bearing 10A, the length of the line segment ab is greater than the length of the line segment cd.

[0042] 6, the first outer ring 20A and the inner ring assembly 35 are arranged such that point a (first end point) and point c (first end point) coincide in a cross section including the center axis C2 of the first outer ring 20A and the center axis C3 of the inner ring 30. When the inner ring assembly 35 is rotated from this state around the tangent to the second great circle BC2 that passes through point a (first end point), the length of the first line segment ab is greater than the length of the line segment cd, and therefore the first ball 41 on the first radial side cannot enter the first inclined surface 23A. In other words, in the first ball bearing 10A, it is difficult to assemble the first outer ring 20A and the inner ring assembly 35 when the center axis C3 of the inner ring 30 is inclined with respect to the center axis C2 of the first outer ring 20A. Therefore, when assembling the first outer ring 20A to the inner ring assembly 35, the first balls 41 are unlikely to come into contact with and get caught on the first inclined surface 23A. In other words, with a first ball bearing 10A configured as described above, it is difficult to assemble the first outer ring 20A and the inner ring assembly 35 when the central axis C3 of the inner ring 30 is inclined relative to the central axis C2 of the first outer ring 20A. Furthermore, with this configuration, it is unlikely that the first outer ring 20A needs to be forcibly pushed into the inner ring assembly 35, which reduces the possibility that the first balls 41 on the first radial side will rub against the first inclined surface 23A and be damaged. In the present disclosure, an assembly characteristic is evaluated as excellent if there is little possibility that the first balls 41 will be damaged when assembling the outer ring 20 and the inner ring assembly 35. Therefore, the first ball bearing 10A can be evaluated as having excellent assembly characteristic.

[0043] (Ball bearing according to the second embodiment) FIG. 7 is a cross-sectional view showing the overall configuration of a ball bearing according to the second embodiment. FIG. 8 is a cross-sectional view showing an outer ring according to the second embodiment. FIG. 9 is a cross-sectional view showing the assembly of the outer ring to the inner ring assembly of the ball bearing according to the second embodiment. FIG. 7 shows a second ball bearing 10B, which is the ball bearing 10 according to the second embodiment. The second ball bearing 10B differs from the first ball bearing 10A in that it has a second outer ring 20B (see FIG. 8), which is the outer ring 20 according to the second embodiment. In this description, the first outer ring raceway 21 of the second outer ring 20B will be referred to as the first outer ring raceway 21B, the second outer ring raceway 22 as the second outer ring raceway 22B, the first inclined surface 23 as the first inclined surface 23B, the second inclined surface 24 as the second inclined surface 24B, and the third inclined surface 25 as the third inclined surface 25B. In this description, the second ball bearing 10B is also simply referred to as the ball bearing 10B, and the first outer ring 20A is also simply referred to as the outer ring 20B.

[0044] For ease of explanation, point e is defined for the second outer ring 20B (see FIG. 8). Point e (fourth end point) is a point located on the first inclined surface 23 on the first radial side in a cross section including the center axis C2 of the second outer ring 20B, and is the point that is shortest from point c (first end point). In the following explanation, the line segment having point c (first end point) and point e (fourth end point) as its end points will be referred to as the third line segment ce. In the circumferential direction of the outer ring 20, points c and e are 180° out of phase with each other. The phase of point e is the same as the phase of point d.

[0045] In the second ball bearing 10B, the length of the first line segment ab is smaller than the length of the second line segment cd, and is also smaller than the length of the third line segment ce.

[0046] 9 are arranged such that point a (first end point) and point c (first end point) coincide with each other in a cross section including the center axis C2 of the second outer ring 20B and the center axis C3 of the inner ring 30. When the inner ring assembly 35 is rotated from this state about a tangent to the second great circle BC2 that passes through point a (first end point), the first balls 41 can enter the first inclined surfaces 23B and can move over the first inclined surfaces 23B into the first outer ring raceway 21B. In other words, in the second ball bearing 10B, when the second outer ring 20B is assembled to the inner ring assembly 35, there is a low possibility that the first balls 41 will come into contact with and become caught on the first inclined surfaces 23B. That is, with the second ball bearing 10B configured as described above, even if the second outer ring 20B and the inner ring assembly 35 are assembled in a state in which the center axis C3 of the inner ring 30 is inclined relative to the center axis C2 of the second outer ring 20B, they can be easily assembled without getting caught. Furthermore, because the second outer ring 20B is unlikely to get caught on the inner ring assembly 35, it is less likely that the second outer ring 20B will need to be forcibly pushed into the inner ring assembly 35, and the possibility of the first balls 41 rubbing against the first inclined surfaces 23B and being damaged can be reduced. For this reason, the second ball bearing 10B can be evaluated as having excellent assembly properties.

[0047] (Ball bearing according to comparative example) FIG. 10 is a cross-sectional view showing the overall configuration of a ball bearing according to a comparative example. FIG. 11 is a cross-sectional view showing an outer ring according to a comparative example. FIG. 12 is a cross-sectional view showing the assembly of the outer ring to the inner ring assembly of the ball bearing according to the comparative example. The ball bearing 60 shown in FIG. 10 differs from the ball bearing 10 of the present disclosure in that it includes an outer ring 70. Note that the ball bearing 60 also includes an inner ring assembly 35 that is common to the ball bearing 10 of the present disclosure. In the following description, the center axis of the ball bearing 60 will be referred to as center axis C4. Similarly, the center axis of the outer ring 70 will be referred to as center axis C5, and the center axis of the inner ring 30 will be referred to as center axis C3. The center axis C5 of the outer ring 70 and the center axis C3 of the inner ring 30 coincide with the center axis C4 of the ball bearing 60 when the inner ring assembly 35 and the outer ring 70 are combined.

[0048] As shown in Figures 10 and 11, in addition to a first outer ring raceway 71 and a second outer ring raceway 72, a first inclined surface 73, a second inclined surface 74, and a third inclined surface 75 are formed on the inner surface of the outer ring 70.

[0049] The first inclined surface 73 is formed on the inner peripheral surface of the outer ring 70 on a second axial side of the first outer ring raceway 71, and is a conical surface whose diameter increases from the first axial side to the second side. The second inclined surface 74 is formed on the inner peripheral surface of the outer ring 70 on the second axial side of the first inclined surface 73, and on the first axial side of the second outer ring raceway 72, and is a conical surface whose diameter increases from the first axial side to the second side. The third inclined surface 75 is formed on the inner peripheral surface of the outer ring 70 on the second axial side of the second outer ring raceway 72, is adjacent to the front surface of the outer ring 70, and is a conical surface whose diameter increases from the first axial side to the second side.

[0050] In a cross section including the central axis C5 of the outer ring 70, a first minor angle θ101 formed between the first inclined surface 73 and the central axis C5 of the outer ring 70 is smaller than a second minor angle θ102 formed between the second inclined surface 74 and the central axis C5 of the outer ring 70 in a cross section including the central axis C5 of the outer ring 70. In a cross section including the central axis C5 of the outer ring 70, the first minor angle θ101 is smaller than a third minor angle θ103 formed between the third inclined surface 75 and the central axis C5 of the outer ring 70.

[0051] For the outer ring 70, points d and e are defined (see FIG. 11) similar to those of the second outer ring 20B (see FIG. 8).

[0052] In ball bearing 60, the length of first line segment ab is smaller than the length of second line segment cd and larger than the length of third line segment ce. Ball bearing 60 differs from ball bearing 10 (first ball bearing 10A and second ball bearing 10B) of the present disclosure in that it has such a dimensional relationship. Ball bearing 60 according to the comparative example is not included in ball bearing 10 of the present disclosure.

[0053] The outer ring 70 and inner ring assembly 35 shown in FIG. 12 are arranged such that point a (first end point) and point c (first end point) coincide in a cross section including the center axis C5 of the outer ring 70 and the center axis C3 of the inner ring 30. When the inner ring assembly 35 is rotated from this state around a tangent to the second great circle BC2 that passes through point a (first end point), the first balls 41 on the first radial side can enter the first inclined surface 73 but cannot pass over the first inclined surface 73 and enter the first outer ring raceway 71. In other words, in the ball bearing 60 according to the comparative example, when the outer ring 70 is assembled to the inner ring assembly 35, the first balls 41 may come into contact with and become stuck on the first inclined surface 73. Furthermore, if the outer ring 70 in a stuck state is forcibly inserted into the inner ring assembly 35, the first balls 41 may rub against the first inclined surface 73 and be damaged. For this reason, the ball bearing 60 can be evaluated as having poor assembly properties.

[0054] [Effects of the embodiment] The ball bearings 10A, 10B in the above-described embodiments include an inner ring assembly 35 and outer rings 20A, 20B. The inner ring assembly 35 includes an inner ring 30, a plurality of first balls 41, a plurality of second balls 42, a first cage 51, and a second cage 52. The inner ring 30 has, on its outer peripheral surface, a first inner ring raceway 31 on a first axial side and a second inner ring raceway 32 on a second axial side of the first inner ring raceway 31. The raceway contact diameter of the first inner ring raceway 31 is smaller than the raceway contact diameter of the second inner ring raceway 32. The plurality of first balls 41 are rollably disposed in the first inner ring raceway 31. The first cage 51 has a plurality of first pockets 53. The plurality of first balls 41 are slidably disposed in the first pockets 53. The plurality of second balls 42 are rollably arranged in the second inner ring raceway 32. The second cage 52 has a plurality of second pockets 54. The plurality of second balls 42 are slidably arranged in the second pockets 54. The inner ring 30, the plurality of first balls 41, the plurality of second balls 42, the first cage 51, and the second cage 52 are configured so as not to separate. The pitch diameter of the ball set in the row of first balls 41 formed by the plurality of first balls 41 of the inner ring assembly 35 is smaller than the pitch diameter of the ball set in the row of second balls 42 formed by the plurality of second balls 42. The outer rings 20A, 20B have, on their inner circumferential surfaces, first outer ring raceways 21A, 21B, first inclined surfaces 23A, 23B, second inclined surfaces 24A, 24B, and second outer ring raceways 22A, 22B, arranged from the first axial side to the second axial side. The inner circumferential surfaces of the outer rings 20A, 20B expand without decreasing in diameter from the first outer ring raceways 21A, 21B to the second outer ring raceways 22A, 22B, and the raceway contact diameter of the first outer ring raceways 21A, 21B is smaller than the raceway contact diameter of the second outer ring raceways 22A, 22B. The diameter of the multiple first balls 41 is smaller than the diameter of the multiple second balls 42. The multiple first balls 41 are rotatably arranged in the first outer ring raceways 21A, 21B. A plurality of second balls 42 are rotatably arranged on second outer ring raceways 22A and 22B. A nominal contact point of first inner ring raceway 31 is located on a second axial side of a nominal contact point of first outer ring raceways 21A and 21B. A nominal contact point of second inner ring raceway 32 is located on a second axial side of a nominal contact point of second outer ring raceways 22A and 22B.The first inclined surfaces 23A, 23B are formed on the inner peripheral surfaces of the outer rings 20A, 20B on a second axial side of the first outer ring raceways 21A, 21B, and are inclined surfaces that increase in diameter from the first axial side toward the second side. The second inclined surfaces 24A, 24B are formed on the inner peripheral surfaces of the outer rings 20A, 20B on the second axial side of the first inclined surfaces 23A, 23B, and on the first axial side of the second outer ring raceways 22A, 22B, and are inclined surfaces that increase in diameter from the first axial side toward the second side. A first minor angle θ1 formed between the first inclined surfaces 23A, 23B and the central axis C2 of the outer rings 20A, 20B in a cross section including the central axis C2 of the outer rings 20A, 20B is smaller than a second minor angle θ2 formed between the second inclined surfaces 24A, 24B and the central axis C2 of the outer rings 20A, 20B in a cross section including the central axis C2 of the outer rings 20A, 20B. When a plurality of first balls 41 are arranged in the first inner ring raceway 31 and are in contact with each other, a first imaginary torus T1 is defined as a torus in which the center of each of the plurality of first balls 41 lies on a first great circle BC1, a first minor radius Sr1 which is the radius of the first small circle SC1 is half the diameter of the first ball 41, and a first major radius Br1 which is the radius of the first great circle BC1 is half the pitch diameter of the ball set in the row of first balls 41. When multiple second balls 42 are placed on the second inner ring raceway 32 and are in contact with each other, the center of each of the multiple second balls 42 is on the second great circle BC2, half the diameter of the second ball 42 is the second minor radius Sr2, which is the radius of the second small circle SC2, and half the pitch diameter of the ball set in the row of second balls 42 is the second major radius Br2, which is the radius of the second great circle BC2, is defined as a torus called a second virtual torus T2.In a cross section including the bearing central axis C1, a first radial side and a second radial side that are 180° opposite to the first radial side in the circumferential direction are defined, a second great circle BC2 on the second radial side is defined as first end points a and c, a first straight line L1 passing through the first great circle BC1 on the first radial side and the second great circle BC2 on the second radial side intersects with the surface of the first radial side of a first virtual torus T1 on the first radial side as second end point b, and the first end point The line segment connecting points a, c and the second endpoint b is defined as the first line segment ab, the point furthest to the second axial side of first inclined surface 23A, 23B on the first radial side is defined as the third endpoint d, the line segment connecting first endpoints a, c and the third endpoint d is defined as the second line segment cd, the point on first inclined surface 23A, 23B on the first radial side that is the closest to first endpoints a, c is defined as the fourth endpoint e, and the line segment connecting first endpoints a, c and the fourth endpoint e is defined as the third line segment ce. In ball bearings 10A and 10B, the length of first line segment ab is longer than the length of second line segment cd (in the case of outer ring 20A), or the length of first line segment ab is shorter than the length of second line segment cd and the length of first line segment ab is shorter than the length of third line segment ce (in the case of outer ring 20B).

[0055] In ball bearings 10A and 10B configured as described above, when assembling outer ring 20 to inner ring assembly 35, first balls 41 do not come into contact with first inclined surface 23 of outer ring 20, and it is possible to prevent outer ring 20 from getting caught and stopping in a state where first balls 41 are in contact with first inclined surface 23. Therefore, according to ball bearings 10A and 10B described in the above embodiment, it is possible to improve the ease of assembling outer ring 20 to inner ring assembly 35.

[0056] In ball bearings 10A and 10B, outer rings 20A and 20B have, on their inner circumferential surfaces, first outer ring raceways 21A and 21B, first inclined surfaces 23A and 23B, second inclined surfaces 24A and 24B, second outer ring raceways 22A and 22B, and third inclined surfaces 25A and 25B, from the first axial side to the second axial side. The inner circumferential surfaces of outer rings 20A and 20B expand without reducing in diameter from first outer ring raceways 21A and 21B to third inclined surfaces 25A and 25B. In ball bearings 10A and 10B, first minor angle θ1 is smaller than third minor angle θ3 formed by third inclined surfaces 25A and 25B and central axis C2 of outer rings 20A and 20B in a cross section including central axis C2 of outer rings 20A and 20B. According to the ball bearings 10A and 10B having such a configuration, the ease of assembling the outer ring 20 to the inner ring assembly 35 can be improved.

[0057] Furthermore, in ball bearings 10A, 10B, the second balls 42 overlap in the axial direction with an imaginary plane that includes the front surfaces of the second axial sides of outer rings 20A, 20B and is perpendicular to the central axes of outer rings 20A, 20B. In this case, for ball bearings 10A, 10B having a configuration in which portions of second balls 42 are exposed radially from outer rings 20A, 20B, the ease of assembling outer rings 20A, 20B to inner ring assembly 35 can be improved.

[0058] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope of the claims and equivalents thereof. [Explanation of symbols]

[0059] 10, 10A, 10B, 60, 110, 210: Ball bearing 20, 20A, 20B, 70, 120, 220: Outer ring 21, 21A, 21B, 71, 121, 221: First outer raceway 22, 22A, 22B, 72, 122, 222: Second outer raceway 23, 23A, 23B, 73, 123: First inclined surface 24, 24A, 24B, 74, 124: Second inclined surface 25, 25A, 25B, 75, 125: Third inclined surface 30, 130: Inner circle 31, 131: First inner raceway 32, 132: Second inner raceway 35, 135: Inner ring assembly 41, 141: First ball 42, 142: Second ball 51: First retainer 52: Second holder 53: First pocket 54: Second pocket θ1: First minor angle θ2: Second minor angle θ3: The third minor angle T1: First virtual torus T2: Second virtual torus SC1: First small circle SC2: Second small circle BC1: First great circle BC2: Second great circle Sr1: First small radius Sr2: Second small radius Br1: First major diameter Br2: Second major diameter L1: First line a, c: first endpoint b: second endpoint d: third endpoint e:Fourth endpoint ab: first line segment cd: second line segment ce: the third line segment

Claims

1. An inner ring assembly and an outer ring, the inner ring assembly includes an inner ring, a plurality of first balls, a plurality of second balls, a first cage, and a second cage; the inner ring has, on an outer peripheral surface thereof, a first inner ring raceway on a first axial side and a second inner ring raceway on a second axial side of the first inner ring raceway; a raceway contact diameter of the first inner ring raceway is smaller than a raceway contact diameter of the second inner ring raceway; the plurality of first balls are rollably disposed in the first inner ring raceway, the first retainer has a plurality of first pockets; the plurality of first balls are slidably disposed in the first pocket; the plurality of second balls are rollably disposed in the second inner ring raceway, the second retainer has a plurality of second pockets; the plurality of second balls are slidably disposed in the second pocket; the inner ring, the plurality of first balls, the plurality of second balls, the first cage, and the second cage are configured not to be separated, the pitch diameter of a ball set in a first row of balls constituted by the plurality of first balls of the inner ring assembly is smaller than the pitch diameter of a ball set in a second row of balls constituted by the plurality of second balls, the outer ring has, on an inner circumferential surface, a first outer ring raceway, a first inclined surface, a second inclined surface, and a second outer ring raceway, arranged from a first side to a second side in an axial direction; an inner peripheral surface of the outer ring expands in diameter from the first outer ring raceway to the second outer ring raceway without reducing in diameter; a raceway contact diameter of the first outer ring raceway is smaller than a raceway contact diameter of the second outer ring raceway; a diameter of the plurality of first balls is smaller than a diameter of the plurality of second balls; the plurality of first balls are rollably disposed in the first outer ring raceway, and the plurality of second balls are rollably disposed in the second outer ring raceway; a nominal contact point of the first inner ring raceway is located on a second axial side of a nominal contact point of the first outer ring raceway; a nominal contact point of the second inner ring raceway is located on a second axial side of a nominal contact point of the second outer ring raceway, the first inclined surface is formed on an inner peripheral surface of the outer ring on a second side in the axial direction of the first outer ring raceway, and is an inclined surface whose diameter increases from the first side toward the second side in the axial direction, the second inclined surface is an inclined surface that is formed on the inner peripheral surface of the outer ring on a second side in the axial direction of the first inclined surface and on a first side in the axial direction of the second outer ring raceway, and that increases in diameter from the first side toward the second side in the axial direction, a first minor angle formed between the first inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring is smaller than a second minor angle formed between the second inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring, and When the plurality of first balls are arranged in contact with the first inner ring raceway, a torus is defined as a first virtual torus in which the center of each of the plurality of first balls is on a first great circle, a first minor radius that is the radius of a first small circle is half the diameter of the first ball, and a first major radius that is the radius of the first great circle is half the pitch diameter of a ball set in the row of first balls, When the plurality of second balls are arranged in contact with the second inner ring raceway, a torus is defined as a second virtual torus in which the center of each of the plurality of second balls is on a second great circle, a second minor radius is the radius of a second small circle that is half the diameter of the second ball, and a second major radius is the radius of the second great circle that is half the pitch diameter of a ball set in the second ball row, In a cross section including the bearing central axis, a first radial side and a second radial side that are 180° opposite to the first radial side in the circumferential direction are defined; the second great circle on the second radial side is a first end point; an intersection point between a line passing through the first great circle on the first side in the radial direction and the second great circle on the second side in the radial direction and a surface of the first virtual torus on the first side in the radial direction is set as a second end point; a line segment connecting the first end point and the second end point is defined as a first line segment; a third end point is a point on the second axial side of the first inclined surface on the first radial side; a line segment connecting the first end point and the third end point is defined as a second line segment; a fourth end point is a point on the first inclined surface on the first side in the radial direction that is the shortest distance from the first end point; a line segment connecting the first end point and the fourth end point is defined as a third line segment; The length of the first line segment is greater than the length of the second line segment. Or, The length of the first line segment is smaller than the length of the second line segment, and A ball bearing, wherein the length of the first line segment is smaller than the length of the third line segment.

2. the outer ring has, on an inner peripheral surface thereof, the first outer ring raceway, the first inclined surface, the second inclined surface, the second outer ring raceway, and a third inclined surface, arranged from a first side to a second side in the axial direction; an inner peripheral surface of the outer ring expands in diameter from the first outer ring raceway to the third inclined surface without reducing in diameter; 2. The ball bearing according to claim 1, wherein the first minor angle is smaller than a third minor angle formed by the third inclined surface and the central axis of the outer ring in a cross section including the central axis of the outer ring.

3. 3. A ball bearing according to claim 1, wherein the plurality of second balls and an imaginary plane that includes a front surface of the outer ring on the second axial side and is perpendicular to the center axis of the outer ring overlap in the axial direction.

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