JP7740382B2 - ball bearing - Google Patents

Description

This disclosure relates to ball bearings.

Conventionally, there is known a double-row angular contact ball bearing in which the minor angle between the bearing center axis and the line of action of each row of balls is in the same direction, and the pitch diameters of the ball sets in each row of balls are different, allowing it to withstand a greater axial load than a single-row angular contact ball bearing. This type of ball bearing is called a tandem type.

Figure 6 is a cross-sectional view of a conventional ball bearing. The conventional ball bearing 210 comprises an inner ring assembly 235 and an outer ring 220. The inner ring assembly 235 comprises 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. The inner ring 230 has, on its outer 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 the first inner ring raceway 231. The raceway contact diameter of the first inner ring raceway 231 is smaller than the raceway contact diameter of the second inner ring raceway 232. The plurality of first balls 241 are rotatably arranged in the first inner ring raceway 231. The first cage 251 has a plurality of pockets. The plurality of first balls 241 are slidably disposed 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 disposed in each pocket of the first cage 251 and then disposed 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 disposed in the second inner ring raceway 232. The second cage 252 has a plurality of pockets. The plurality of second balls 242 are slidably disposed in the plurality of pockets of the second cage 252. The diameter of the inscribed circle of the radially outer openings of the plurality of pockets of the second cage 252 is smaller than the diameter of the second balls 242, so when the plurality of 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 plurality of 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 plurality of first balls 241, the plurality of 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 plurality of 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 plurality of second balls 242.

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.

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. Because the ball bearing 210 has two rows of balls, the axial load that the ball bearing 210 can withstand is greater than the axial load that a single-row angular contact ball bearing can withstand (see, for example, Patent Document 1).

In contrast, in conventional ball bearings 210, the diameter of the first balls 241 is the same as the diameter of the second balls 242. In this case, the service life of the row of first balls 241, the first inner ring raceway 231, and the first outer ring raceway 221 may differ significantly from the service life of the row of second balls 242, the second inner ring raceway 232, and the second outer ring raceway 222. By making the diameter of the multiple first balls 241 in conventional ball bearings 210 smaller than the diameter of the multiple second balls 242, the difference between the service life of the row of first balls 241 and the service life of the row of second balls 242 can be reduced, making it possible to optimize the service life, rigidity, torque, etc. of the ball bearing 210.

JP 2015-194244 A

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 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, the plurality of first balls being slidably disposed in the first pockets, and the plurality of second balls being in contact with 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 be separated, the pitch diameter of a ball set in a first ball row formed by the plurality of first balls of the inner ring assembly is smaller than the pitch diameter of a ball set in a 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, an inner peripheral surface of the ring expands without reducing in diameter from the first outer ring raceway to the second outer ring raceway, 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 arranged in the first outer ring raceway, the plurality of second balls are rollably arranged in the second outer ring raceway, a nominal contact point of the first inner ring raceway is located on a second side in the axial direction 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 side in the axial direction of a nominal contact point of the second outer ring raceway, the first inclined surface is an inclined surface formed on the inner peripheral surface of the outer ring on a second axial side of the first outer ring raceway, and widens in diameter from the first axial side toward the second side; the second inclined surface is an inclined surface formed on the inner peripheral surface of the outer ring on the second axial side of the first inclined surface, on the first axial side of the second outer ring raceway, and widens in diameter from the first axial side toward the second side; 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 the first minor angle is 12° or less.

In the ball bearing disclosed herein, the outer ring has, on its inner peripheral surface, from the first side in the axial direction to the second side, 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 peripheral 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.

1 is a cross-sectional view showing the overall configuration of a ball bearing; FIG. 2 is a cross-sectional view showing an inner ring assembly. FIG. FIG. 2 is a cross-sectional view showing the outer ring. FIG. 4 is a partially enlarged cross-sectional view showing a first inclined surface and a second inclined surface. FIG. 1 is a cross-sectional view showing a conventional double-row ball bearing. FIG. 4 is a cross-sectional view showing a double-row ball bearing of a comparative example. FIG. 4 is a partially enlarged cross-sectional view showing a first inclined surface and a second inclined surface in a double-row ball bearing according to a comparative example. FIG. 10 is a cross-sectional view showing the state in which the outer ring is assembled to the inner ring assembly in a double-row ball bearing according to a comparative example.

<Problems to be Solved by the Invention of the Present Disclosure>
Fig. 7 is a cross-sectional view showing a comparative double-row ball bearing. Fig. 8 is a partially enlarged cross-sectional view showing the first inclined surface and the second inclined surface in the comparative double-row ball bearing. Fig. 9 is a cross-sectional view showing the assembly of the outer ring to the inner ring assembly in the comparative double-row ball bearing. The double-row ball bearing in Fig. 7 is configured such that the second balls 242 of the conventional double-row ball bearing 210 shown in Fig. 6 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 disposed in the first inner ring raceway 131. The first cage 151 has a plurality of pockets. The plurality of first balls 141 are slidably disposed in the plurality of pockets of the first cage 151. Because the diameter of the inscribed circle of the radially outer openings of the multiple pockets of the first cage 151 is smaller than the diameter of the first balls 141, when the multiple first balls 141 are placed in each pocket of the first cage 151 and then placed in the first inner ring raceway 131, the inner ring 130, the multiple first balls 141, and the first cage 151 do not separate. The multiple second balls 142 are rollably disposed in the second inner ring raceway 132. The second cage 152 has multiple pockets. The multiple second balls 142 are slidably disposed in the multiple pockets of the second cage 152. Because the diameter of the inscribed circle of the radially outer openings of the plurality of pockets of the second cage 152 is smaller than the diameter of the second balls 142, when the plurality of second balls 142 are placed in each pocket of the second cage 152 and arranged in the second inner ring raceway 132, the inner ring 130, the plurality of second balls 142, and the second cage 152 do not separate. In this manner, the inner ring 130, the plurality of first balls 141, the plurality of second balls 142, the first cage 151, and the second cage 152 are configured not to separate. In the inner ring assembly 135, the pitch diameter of the ball set in the row of first balls 141 formed by the plurality of first balls 141 is smaller than the pitch diameter of the ball set in the row of second balls 142 formed by the 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 axial 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 axial 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.

As shown in Figure 8, in a cross section including the center axis C102 of the outer ring 120, the first minor angle θ101 formed by the first inclined surface 123 and the center axis C102 of the outer ring 120 is smaller than the second minor angle θ102 formed by the second inclined surface 124 and the center axis C102 of the outer ring 120 in a cross section including the center axis C102 of the outer ring 120. In a cross section including the center axis C102 of the outer ring 120, the first minor angle θ101 is smaller than the third minor angle θ103 formed by the third inclined surface 125 and the center axis C102 of the outer ring 120. The first minor angle θ101 is greater than 12°.

In a ball bearing 110 configured as shown in Figure 9, if the center axis C102 of the outer ring 120 is tilted relative to the center axis C103 of the inner ring assembly 135 when assembling the outer ring 120 to the inner ring assembly 135, the first ball 141 may be tightly pinched between the first inclined surface 123 and the first inner ring raceway 131, causing contact and preventing the first ball 141 from sliding, resulting in a smooth assembly failure (the ball may become stuck in its tilted position). In such a case, if the outer ring 120 is forcibly pushed into the inner ring assembly 135, the first ball 141 may become caught in the outer ring 120, damaging the first ball 141.

The purpose of this disclosure is to improve the assembly of the outer ring to the inner ring assembly in a ball bearing and to reduce damage to the ball bearing.

<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.

<Summary of the embodiment of the present disclosure>
Below, an outline of the embodiments of the present disclosure will be listed and described.

(1) The ball bearing of the present disclosure comprises an inner ring assembly and an outer ring. The inner ring assembly comprises 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 its outer 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 are rollably arranged in the first inner ring raceway. The first cage has a plurality of first pockets, and the plurality of first balls are slidably arranged in the plurality of first pockets of the first cage. The plurality of second balls are rollably arranged in the second inner ring raceway. The second cage has a plurality of second pockets, and the plurality of second balls are slidably disposed in the plurality of second pockets of the second cage. The inner ring assembly is configured so that the inner ring, the plurality of first balls, the plurality of second balls, the first cage, and the second cage are not separated. The pitch diameter of a row of ball sets formed by the plurality of first balls in the inner ring assembly is smaller than the pitch diameter of a row of ball sets formed by the plurality of second balls. The diameter of the plurality of first balls is smaller than the diameter of the plurality of second balls. The outer ring has, on its inner circumferential surface, a first outer ring raceway, a first inclined surface, a second inclined surface, and a second outer ring raceway, from the first side to the second side in the axial direction. The inner circumferential surface of the outer ring expands from the first outer ring raceway to the second outer ring raceway without reducing in diameter. The raceway contact diameter of the first outer ring raceway is smaller than the raceway contact diameter of the second outer ring raceway. The multiple first balls are rollably arranged on the first outer ring raceway. The multiple second balls are rollably arranged on the second outer ring raceway. The nominal contact point of the first inner ring raceway is located on a second axial side of the nominal contact point of the first outer ring raceway, and the nominal contact point of the second inner ring raceway is located on a second axial side of the nominal contact point of the second outer ring raceway. The first inclined surface is an inclined surface formed on the inner peripheral surface of the outer ring on the second axial side of the first outer ring raceway, and widens in diameter from the first axial side to the second side. The second inclined surface is an inclined surface 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, and widens in diameter from the first axial side to the second side. In the ball bearing, 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 the first minor angle is 12° or less.

In a ball bearing of this configuration, by setting the first minor angle to 12° or less, the ease of assembly of the outer ring to the inner ring assembly can be improved and damage to the ball bearing can be suppressed.

(2) In the ball bearing of the present disclosure, preferably, the outer ring has, from the first side to the 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 on its inner circumferential 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. In the ball bearing, 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.

<Details of the embodiment of the present disclosure>
Hereinafter, embodiments of the present disclosure will be described.
[About ball bearings]
FIG. 1 is a cross-sectional view showing the overall configuration of a ball bearing. 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 is referred to as the first axial side, and the direction 180° opposite to the first axial side along the center axis of the ball bearing 10 is referred to as the second axial side.

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

Figure 3 is a cross-sectional view of the inner ring. The inner ring 30 is made of a steel material such as high-carbon chromium bearing steel, carbon steel, or alloy steel. The inner ring 30 is cylindrical. The inner ring 30 has, from the first axial side to the second axial side, 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 surface. The first shoulder has a cylindrical outer 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 below). The second shoulder has a conical outer 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 below). The third shoulder has a cylindrical outer 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.

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.

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 constitutes a plurality of second pockets 54 that hold the second balls 42. The diameter of the inscribed circle of the radially outer openings of the plurality of 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.

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. Because 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 balls 41 do not fall out radially outward from the first pockets 53 of the first cage 51. Furthermore, the diameter of the cylindrical surface of the outer peripheral 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.

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, allowing the second cage 52 to hold the second balls 42 at equal intervals along the circumferential direction. Because 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, the second balls 42 do not fall out radially outward from the second pockets 54 of the second cage 52. Furthermore, 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. Furthermore, 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.

As shown in Figure 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.

(Detailed shape of outer ring)
FIG. 4 is a cross-sectional view showing the outer ring. FIG. 5 is a partially enlarged cross-sectional view showing the first inclined surface and the second inclined surface. 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, on its inner circumferential surface, 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, from the first axial side to the second axial side. The inner circumferential surface of the outer ring 20 expands without reducing in diameter from the first outer ring raceway 21 to the third inclined surface 25. 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.

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 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, 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 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, 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 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 .

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 12° or less. The second minor angle θ2 is preferably 25° or greater and 75° or less. The third minor angle θ3 is preferably equal to or greater than 25° and equal to or less than 75°.

(ball bearing)
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.

(Evaluation of the sticking property when assembling ball bearings)
Table 1 below shows the results of checking the grip of the outer ring on the inner ring assembly. Table 1 shows the results for a ball bearing according to an example, which is one embodiment of a ball bearing according to the present disclosure, and ball bearings according to comparative examples 1 to 3. The configuration of ball bearings 110 according to comparative examples 1 to 3 differs from ball bearing 10 according to the example in that the first minor angle θ1 of ball bearing 10 according to the example is 12° or less, while the first minor angle θ101 of ball bearings 110 according to comparative examples 1 to 3 exceeds 12°. Note that "stuck" here refers to a situation in which, when the back surface of the inner race assembly 35, 135 is placed on a horizontal plane, the central axis C2 of the outer race 20, 120 is tilted 30° relative to the central axis C3 of the inner race assembly 35, 135, and the outer race 20, 120 is placed on the inner race assembly 35, 135, and the outer race 20, 120 is able to move to a normal relative position with respect to the inner race assembly 35 due to the weight of the outer race 20, 120, it is determined that "not stuck," and when the first inclined surface 123 of the outer race 120 comes into contact with the first ball 141 of the inner race assembly 135 and stops, and the outer race 120 cannot move to a normal relative position with respect to the inner race assembly 135 without further pressure on the outer race 120, it is determined that "stuck." Note that even if the outer race 120 gets stuck on the inner race assembly 135, it can be moved to a normal relative position with respect to the inner race assembly 135 with further pressure. In the present disclosure, the assembly is evaluated as excellent when there is little possibility of damaging the first ball 41 when assembling the outer ring 20 and the inner ring assembly 35. Therefore, "no sticking" can be evaluated as excellent assembly.

The ball bearing 10 according to the example shown in Table 1 has a first minor angle θ1 of 11° (angles less than 1/2 arcminute are rounded down), a second minor angle θ2 of 38° (same as above), and a third minor angle θ3 of 34° (same as above). Thus, in the ball bearing 10 according to the example, the first minor angle θ1 is smaller than the second minor angle θ2 (θ1 < θ2). Furthermore, in the ball bearing 10 according to the example, the first minor angle θ1 is smaller than the third minor angle θ3 (θ1 < θ3). Furthermore, in the ball bearing 10 according to the example, the first minor angle θ1 is 12° or less. The ball bearing 10 according to the example configured in this way experienced "no" jamming when assembling the outer ring 20 to the inner ring assembly 35. Therefore, the ball bearing 10 according to the example has good assembly properties.

The ball bearing 110 according to Comparative Example 1 shown in Table 1 has a first minor angle θ101 of 18° (angles less than 1/2 arcminute are rounded down), a second minor angle θ102 of 38° (same as above), and a third minor angle θ103 of 27° (same as above). Thus, in the ball bearing 110 according to Comparative Example 1, the first minor angle θ101 is smaller than the second minor angle θ102 (θ101 < θ102). Also, in the ball bearing 110 according to Comparative Example 1, the first minor angle θ101 is smaller than the third minor angle θ103 (θ101 < θ103). Meanwhile, the first minor angle θ101 of the ball bearing 110 according to Comparative Example 1 exceeds 12°. The ball bearing 110 according to Comparative Example 1, which has this configuration, experienced jamming when assembling the outer ring 120 to the inner ring assembly 135. Therefore, the ball bearing 110 according to Comparative Example 1 has poor assembly properties.

The ball bearing 110 according to Comparative Example 2 shown in Table 1 has a first minor angle θ101 of 18° (angles less than 1/2 minute are rounded down), a second minor angle θ102 of 38° (same as above), and a third minor angle θ103 of 27° (same as above). Thus, in the ball bearing 110 according to Comparative Example 2, the first minor angle θ101 is smaller than the second minor angle θ102 (θ101 < θ102). Also, in the ball bearing 110 according to Comparative Example 2, the first minor angle θ101 is smaller than the third minor angle θ103 (θ101 < θ103). Meanwhile, the first minor angle θ101 of the ball bearing 110 according to Comparative Example 2 exceeds 12°. The ball bearing 110 of Comparative Example 2 is identical to the ball bearing 110 of Comparative Example 1 in the first minor angle θ101, the second minor angle θ102, the third minor angle θ103, and the diameters of the first balls 141 and second balls 142, but is different in the raceway contact diameters of the first inner ring raceway 131, the second inner ring raceway 132, the first outer ring raceway 121, and the second outer ring raceway 122. The ball bearing 110 of Comparative Example 2, which has this configuration, experienced some sticking when assembling the outer ring 120 to the inner ring assembly 135. For this reason, the ball bearing 110 of Comparative Example 2 has poor assembly properties.

The ball bearing 110 according to Comparative Example 3 shown in Table 1 has a first minor angle θ101 of 19° (angles less than 1/2 minute are rounded down), a second minor angle θ102 of 38° (same as above), and a third minor angle θ103 of 27° (same as above). Thus, in the ball bearing 110 according to Comparative Example 3, the first minor angle θ101 is smaller than the second minor angle θ102 (θ101 < θ102). Furthermore, in the ball bearing 110 according to Comparative Example 3, the first minor angle θ101 is smaller than the third minor angle θ103 (θ101 < θ103). Meanwhile, the first minor angle θ101 of the ball bearing 110 according to Comparative Example 3 exceeds 12°. The ball bearing 110 according to Comparative Example 3, which has this configuration, experienced jamming when assembling the outer ring 120 to the inner ring assembly 135. Therefore, the ball bearing 110 according to Comparative Example 3 has poor assembly properties.

The results of the confirmation tests shown in Table 1 show that the ball bearing 10 according to the example, in which the first minor angle θ1 is 12° or less, does not stick and has excellent assembly properties. On the other hand, the ball bearings 110 according to comparative examples 1 to 3, in which the first minor angle θ101 exceeds 12°, stick and all have poor assembly properties. From the above, it has been confirmed that by setting the first minor angle θ1 to 12° or less, the ball bearing 10 improves the assembly properties of the outer ring 20 to the inner ring assembly 35 and suppresses damage to the ball bearing 10.

[Effects of the embodiment]
The ball bearing 10 in the embodiment described above includes an inner ring assembly 35 and an outer ring 20. 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, and 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, and the plurality of first balls 41 are slidably disposed in the plurality of first pockets 53. The plurality of second balls 42 are rollably disposed 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 disposed in the plurality of second pockets 54. 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 are not separated. The pitch diameter of the ball sets in the row of first balls 41 of the inner ring assembly 35, which are formed by the plurality of first balls 41, is smaller than the pitch diameter of the ball sets in the row of second balls 42, which are formed by the plurality of second balls 42. The outer ring 20 has, on its inner circumferential surface, a first outer ring raceway 21, a first inclined surface 23, a second inclined surface 24, and a second outer ring raceway 22, from the first side to the second side in the axial direction. The inner peripheral surface of the outer ring 20 expands without reducing in diameter from the first outer ring raceway 21 to the second outer ring raceway 22. 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. The diameter of the plurality of first balls 41 is smaller than the diameter of the plurality of second balls 42. The plurality of first balls 41 are rollably arranged in the first outer ring raceway 21. The 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 a second axial side of the nominal contact point of the first outer ring raceway 21, and the nominal contact point of the second inner ring raceway 32 is located on a second axial side of the nominal contact point of the second outer ring raceway 22. 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 an inclined surface that widens in diameter from the first axial side to the second 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, on the first axial side of the second outer ring raceway 22, and is an inclined surface that widens in diameter from the first axial side to the second side. In the ball bearing 10, the first minor angle θ1 formed between the first inclined surface 23 and the central axis C2 of the outer ring 20 in a cross section including the central axis C2 of the outer ring 20 is smaller than the second minor angle θ2 formed between the second inclined surface 24 and the central axis C2 of the outer ring 20 in a cross section including the central axis C2 of the outer ring 20, and the first minor angle θ1 is 12° or less.

In a ball bearing 10 configured as described above, setting the first minor angle θ1 to 12° or less improves the ease of assembly of the outer ring 20 to the inner ring assembly 35 and reduces damage to the ball bearing 10. In this case, even if the center axis C2 of the outer ring 20 is inclined relative to the center axis C3 of the inner ring assembly 35 when assembling the outer ring 20 to the inner ring assembly 35, the first ball 41 can slide in contact with the first inclined surface 23 and the first outer ring raceway 21 without being tightly pinched, allowing for smooth assembly. As a result, the outer ring 20 does not need to be forcibly pushed into the inner ring assembly 35, and damage to the first ball 41 caused by the first ball 41 becoming caught in the outer ring 20 can be reduced.

In addition, in the ball bearing 10 of this embodiment, the outer ring 20 has, from the first side to the second side in the axial direction, 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 circumferential surface. The inner circumferential surface of the outer ring 20 expands from the first outer ring raceway 21 to the third inclined surface 25 without reducing in diameter. In the ball bearing 10, 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 a cross section including the central axis C2 of the outer ring 20. In a ball bearing 10 configured in this manner, the second ball 42 does not get caught on the front surface of the outer ring 20, and the outer ring 20 can be easily assembled into the inner ring assembly 35.

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 equivalents to the configurations described in the claims.

10, 110, 210: Ball bearing 20, 120, 220: Outer ring 21, 121, 221: First outer ring raceway 22, 122, 222: Second outer ring raceway 23, 123: First inclined surface 24, 124: Second inclined surface 25, 125: Third inclined surface 30, 130, 230: Inner ring 31, 131, 231: First inner ring raceway 32, 132, 232: Second inner ring raceway 35, 135, 235: Inner ring assembly 41, 141, 241: First ball 42, 142, 242: Second ball θ1, θ101: First minor angle θ2, θ102: Second minor angle θ3, θ103: Third minor angle

Claims (2)

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 separate from each other,
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 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 the first minor angle is 12° or less. the outer ring has, on an inner circumferential surface, the first outer ring raceway, the first inclined surface, the second inclined surface, the second outer ring raceway, and a third inclined surface, 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 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.