JP2023128290A - ball bearing - Google Patents

Abstract

To provide a ball bearing capable of reducing rotational resistance.SOLUTION: A ball bearing 18 includes an outer ring 11, an inner ring 12, a plurality of balls 13, and a retainer 14. The retainer 14 has an annular portion 20 and a plurality of pillar portions 21. Each space between two neighboring pillar portions 21, 21 in a circumferential direction is defined to be a pocket 22. The pocket 22 has a pocket face 23 opposed to the ball 13. The pocket face 23 has a recessed face 30, a first plane 31 formed on an axial one side with respect to a pocket center and capable of being kept in contact with the ball 13, a third plane 33 formed on the axial other side with respect to the pocket center at the first pillar portion and capable of being kept in contact with the ball 13, and a fourth plane 34 formed on the axial other side with respect to the pocket center at the second pillar portion and capable of being kept in contact with the ball 13. The first plane 31 crosses an extension line of an auto-rotation axis of the ball 13, and the ball 13 is retained by the retainer 14, kept in point-contact with at least one plane among the first plane 31, the third plane 33 and the fourth plane 34.SELECTED DRAWING: Figure 3

Description

The present invention relates to ball bearings.

Ball bearings are used in a variety of rotating equipment. Patent Document 1 discloses a ball bearing used for a wheel bearing. A ball bearing includes an outer ring, an inner ring, a plurality of balls provided between the outer ring and the inner ring, and a cage that holds the plurality of balls. The holder has a pocket for holding the ball, and the pocket has a pocket surface shaped along a virtual spherical surface whose center is the same as the ball to be held. That is, the pocket has a pocket surface that is entirely spherical.

Japanese Patent Application Publication No. 2014-77508

Generally, a lubricant such as grease is used in rolling bearings such as ball bearings. In such rolling bearings, factors of rotational resistance (rotational torque) include agitation resistance of the grease and rolling viscous resistance of the grease. Since the stirring resistance of the grease includes the shearing resistance of the grease, in order to reduce the rotational resistance of the rolling bearing, it is preferable to reduce the shearing resistance of the grease.

As described above, in the case of the ball bearing disclosed in Patent Document 1, the pocket of the retainer has a pocket surface that is entirely spherical. In this case, the ball and the pocket surface come into contact within an elliptical range, approaching surface contact. For this reason, it is difficult to ensure the thickness of the grease in the contact area, and the shear resistance of the grease tends to increase as explained by the following equation (1).

The shear resistance F of grease is expressed by the following equation (1).
F=η・u・S/h...(1)
In equation (1), η is the viscosity of the grease, u is the speed, S is the sliding area, and h is the thickness of the grease.
When a ball comes into contact with a spherical pocket surface, it is difficult to ensure the grease thickness h, and as a result, shear resistance increases and rotational resistance increases.

Therefore, an object of the present disclosure is to provide a ball bearing that can reduce rotational resistance.

(1) The ball bearing of the present disclosure includes an outer ring, an inner ring, a plurality of balls that are rotatably provided between the outer ring and the inner ring, and a cage that holds the plurality of balls. , the retainer has an annular portion located on one axial side of the ball, and a plurality of column portions extending from the annular portion to the other axial side of the annular portion. A space between the two columnar parts adjacent in the circumferential direction on the side is a pocket that accommodates one of the balls, and the pocket has a pocket surface facing the ball, and the ball is accommodated in the pocket. When the center of the ball is defined as the pocket center, the pocket surface has a concave surface, a first plane formed on one side in the axial direction of the pocket center and capable of contacting the ball, and a circumferential direction. A third plane formed on the other side in the axial direction of the pocket center in one of the two adjacent pillar parts and capable of contacting the ball, and the two pillars adjacent in the circumferential direction. a fourth plane formed on the other side in the axial direction of the pocket center in the other second pillar section and capable of contacting the ball, and the first plane is parallel to the rotation axis of the ball. The ball intersects with an extension line of the ball, and the ball is held in the holder while being in point contact with at least one of the first plane, the third plane, and the fourth plane.

According to the ball bearing of the present disclosure, when the balls are held in the retainer in contact with at least one of the first plane, the third plane, and the fourth plane of the pocket surface, the contact In position the ball makes point contact with the plane. Therefore, at the contact position, a lubricant such as grease is likely to be present between the pocket surface (the plane) and the ball, and it is possible to reduce the rotational resistance of the ball bearing. Furthermore, at a point on the outer surface of the ball that intersects with the ball's rotation axis, the circumferential speed (rotation speed) of the ball becomes slow (approaches 0). It becomes possible to further reduce the shear resistance of the lubricant due to contact.

(2) Preferably, the cage does not contact the inner ring and the outer ring even when displaced in the radial and axial directions, and when the cage is displaced in the radial and axial directions, the cage does not contact the inner ring and the outer ring. Point contact is made with the ball on at least one plane among the one plane, the third plane, and the fourth plane. In this case, the cage becomes a bearing for guiding rolling elements in which the cage is positioned in the radial and axial directions by the balls. Even in the case of a rolling element guide in which the pocket surface contacts the balls and the cage is positioned by the balls, a configuration in which the balls make point contact with the plane can be obtained.

(3) Preferably, the ball does not contact the concave surface, but makes point contact with at least one of the first plane, the third plane, and the fourth plane. When a ball and a concave surface come into contact, they contact within an elliptical area, approaching surface contact, and the shear resistance of the lubricant tends to be large. However, according to the above configuration, the ball is in contact with a pocket surface (the above-mentioned plane). Since the ball bearing is in point contact with the ball bearing, the shear resistance of the lubricant is reduced, making it possible to reduce the rotational resistance of the ball bearing.

(4) Preferably, the first column portion has a first claw portion at the other end in the axial direction, and the second column portion has a second claw portion at the other end in the axial direction, The distance between the first claw part and the second claw part is smaller than the diameter of the ball, the third plane is formed in the first claw part, and the fourth plane is formed in the second claw part. has been done. When assembling the balls and the retainer, it is sufficient to bring the balls closer to the pocket in one direction in the axial direction and to elastically deform a portion of the first claw portion and the second claw portion, which facilitates the assembly. Separation of the balls and retainer is prevented in a state where the assembly is completed.

According to the present disclosure, it is possible to reduce rotational resistance in a ball bearing.

FIG. 1 is a sectional view showing an example of a bearing device including a ball bearing. FIG. 2 is a cross-sectional view of the first ball bearing. FIG. 3 is a cross-sectional view of the first ball bearing in which the balls are omitted. FIG. 4 is a perspective view of a plurality of balls and a retainer. FIG. 5 is a perspective view of the cage. FIG. 6 is an explanatory diagram showing an enlarged view of the pocket. FIG. 7 is a perspective view of a portion of the cage viewed from the inner circumferential side. FIG. 8 is a diagram showing modification example 1 of the cage. FIG. 9 is a diagram showing a second modification of the cage. FIG. 10 is an explanatory diagram showing another type of cage.

FIG. 1 is a sectional view showing an example of a bearing device including a ball bearing. A bearing device 10 shown in FIG. 1 is a wheel bearing device (hub unit) used in an automobile. The bearing device 10 rotatably supports a wheel with respect to a suspension device provided on a vehicle body. The bearing device 10 includes a cylindrical outer ring 11, an inner shaft member 12 located radially inside the outer ring 11, and a plurality of balls 13 arranged in two rows between the outer ring 11 and the inner shaft member 12. , and an annular holder 14 that holds a plurality of balls 13.

The row composed of a plurality of balls 13 on the vehicle inner side (right side in FIG. 1) is defined as a first row L1, and the row composed of a plurality of balls 13 on the vehicle outer side (left side in FIG. 1) is defined as a second row L1. Define column L2. Two holders 14 are provided, and one holder 14 holds a plurality of balls 13 included in each row. The inner shaft member 12 has an inner shaft 16 and an inner ring 17 attached to the vehicle inner side of the inner shaft 16.

A first ball bearing 18 is configured by the plurality of balls 13 included in the first row L1, a first portion 11a that is a part of the outer ring 11 on the vehicle inner side, and the inner ring 17. The first portion 11a of the outer ring 11 corresponds to the "outer ring" of the first ball bearing 18, and the inner ring 17 corresponds to the "inner ring" of the first ball bearing 18. A plurality of balls 13 included in the second row L2, a second portion 11b that is a part of the outer ring 11 on the vehicle outer side, and a third portion 16a that is a part of the inner shaft 16 on the vehicle outer side A second ball bearing 19 is configured. The second portion 11b of the outer ring 11 corresponds to the “outer ring” of the second ball bearing 19, and the third portion 16a of the inner shaft 16 corresponds to the “inner ring” of the second ball bearing 19. The retainer 14 for the first row L1 and the retainer 14 for the second row L2 have the same configuration, although the mounting directions are opposite. The first ball bearing 18 will be explained below. In order to maintain the lubrication performance in the bearing device 10, the ball bearing 18 is lubricated with a lubricant such as grease.

FIG. 2 is a cross-sectional view of the first ball bearing 18. FIG. 3 is a cross-sectional view of the first ball bearing 18 with the balls 13 omitted. In FIG. 3, the ball 13 is shown by a virtual line (two-dot chain line).
For the description of this disclosure, each direction will be defined. The center line C of the ball bearing 18 coincides with the center line of the bearing device 10 shown in FIG. The direction along the center line C of the ball bearing 18 is defined as the "axial direction." This axial direction also includes a direction parallel to the center line C. In the first ball bearing 18, the vehicle outer side (left side in FIGS. 2 and 3) is defined as one axial side, and the vehicle inner side (right side in FIGS. 2 and 3) is defined as the other axial side. A direction perpendicular to the center line C is defined as a "radial direction." A direction along a circle centered on the center line C is defined as a "circumferential direction." The direction in which the inner ring 17 rotates around the center line C is the "circumferential direction."

As shown in FIGS. 2 and 3, the ball bearing 18 is rotatably provided between the outer ring 11 (the first portion 11a of the outer ring 11), the inner ring 17, and the outer ring 11 and the inner ring 17. It includes a plurality of balls 13 and a holder 14 that holds the plurality of balls 13. All of the plurality of balls 13 have the same shape (same diameter). Pockets 22, which will be described later, in which the balls 13 are accommodated all have the same shape.

The outer ring 11 has an outer raceway surface 51 with which the balls 13 roll and come into contact. The inner ring 17 has an inner raceway surface 52 with which the balls 13 roll and come into contact. The balls 13 make contact with the outer raceway surface 51 and the inner raceway surface 52 at a contact angle θ. In other words, the straight line Q connecting the contact point between the ball 13 and the outer raceway surface 51 and the contact point between the ball 13 and the inner raceway surface 52 is inclined at an angle θ with respect to the reference line J perpendicular to the center line C. are doing. When the ball bearing 18 rotates (when the inner ring 17 rotates), the balls 13 rotate around a rotation center line S perpendicular to the straight line Q. That is, the rotation center line S becomes the rotation axis of the ball 13.

FIG. 4 is a perspective view of the plurality of balls 13 and the retainer 14. In FIG. 4, one ball 13 is omitted for explanation. FIG. 5 is a perspective view of the retainer 14. The retainer 14 includes an annular portion 20 located on one side of the balls 13 in the axial direction and a plurality of pillar portions 21 . The annular portion 20 is an annular portion. The column portion 21 is a portion extending from the annular portion 20 to the other side in the axial direction.

A space between two circumferentially adjacent columnar parts 21, 21 on the other axial side of the annular part 20 is a pocket 22 that accommodates one ball 13. The retainer 14 shown in FIGS. 4 and 5 is a so-called crown-shaped retainer. The retainer 14 and the balls 13 are assembled by bringing the balls 13 closer to the pocket 22 toward one side in the axial direction and housing the balls 13 in the pocket 22. At this time, as will be explained later, the tip of the column 21 is elastically deformed. Once the ball 13 is accommodated in the pocket 22, the ball 13 cannot fall out of the pocket 22 in the axial and radial directions.

Each column 21 includes a column main body 24 extending from the annular portion 20 and a pair of claws provided on both circumferential sides of the column main body 24 at the other axial end of each column 21. 25, 25. The claw portion 25 protrudes from the column body 24 in the circumferential direction. FIG. 6 is an explanatory diagram showing the pocket 22 in an enlarged manner. In FIG. 6, attention is paid to two pillar portions 21, 21 that are adjacent to each other in the circumferential direction. One of the two pillar parts 21, 21 is called "first pillar part 21a", and the other is called "second pillar part 21b". Among the pair of claw portions 25, 25 of the first column portion 21a, the side closer to the second column portion 21b is referred to as a “first claw portion 25a”. Among the pair of claws 25, 25 of the second column 21b, the side closer to the first column 21a is referred to as a "second claw 25b." The distance between the first claw portion 25a and the second claw portion 25b (the minimum value B of the distance) is smaller than the diameter D of the ball 13 (see FIG. 4). FIG. 7 is a perspective view of a portion of the retainer 14 viewed from the inner peripheral side.

When assembling the balls 13 and the retainer 14, it is sufficient to move the balls 13 toward the pocket 22 toward one side in the axial direction and to elastically deform a portion of the first claw portion 25a and the second claw portion 25b. becomes easier. In the intermediate state where the balls 13 and the retainer 14 have been assembled, the balls 13 and the retainer 14 are connected by the other axial surface of the annular portion 20, the first claw portion 25a, and the second claw portion 25b. separation in the axial and radial directions is prevented. More specifically, in the intermediate state in which the balls 13 and the retainer 14 have been assembled, a first plane 31 (described later) formed on the other axial surface of the annular portion 20 and a first claw portion Separation of the balls 13 and the retainer in the axial and radial directions is prevented by a third plane 33, which will be described later, formed on the second claw portion 25a and a fourth plane 34, which will be described later, formed on the second claw portion 25b. .

6 and 7, pocket 22 has a pocket surface 23 facing ball 13. In FIGS. The pocket surface 23 has a concave surface 30, a first plane 31, a third plane 33, and a fourth plane 34. The concave surface 30 is a concave curved surface facing the ball 13, and in this embodiment has a shape (concave shape) along a virtual spherical surface K having the same center as the ball 13 to be held. The center of the ball 13 accommodated in the pocket 22 is defined as a pocket center P. The first plane 31 is formed on one side of the pocket center P in the axial direction and can come into contact with the ball 13. The third plane 33 and the fourth plane 34 are formed on the other side of the pocket center P in the axial direction, and can come into contact with the ball 13. Note that since the ball 13 is slightly displaced within the pocket 22, the pocket center P defined as described above includes a region that is displaced due to such displacement.

The arrangement of each plane will be explained in more detail. The first plane 31 is formed on the annular portion 20 (the other axial surface of the annular portion 20). The first plane 31 is formed inside the annular portion 20 in the radial direction. In the two circumferentially adjacent first column parts 21a and second column parts 21b, a third plane 33 is formed on the first claw part 25a of the first column part 21a, and a third plane 33 is formed on the first claw part 25a of the second column part 21b. A fourth plane 34 is formed on the claw portion 25b.

The first plane 31 is a plane, and is a plane that intersects with the inner circumferential surface 20i of the retainer 14 (annular portion 20). The first plane 31 is a circular plane with a portion missing. As shown in FIG. 3, the first plane 31 intersects with an extension of the rotation axis (rotation center line S) of the ball 13. In this embodiment, the first plane 31 is perpendicular to the extension line of the rotation axis (rotation center line S) of the ball 13. When the retainer 14 is displaced to the other side in the axial direction, the first plane 31 can make point contact with the balls 13. When the retainer 14 is displaced radially outward, the first plane 31 can make point contact with the balls 13 .

As shown in FIG. 7, the third plane 33 is the other axial end of the column 21, that is, the tip of the column 21 (claw 25). is formed radially outward. The third plane 33 is a plane that intersects with the outer circumferential surface of the retainer 14 (radially outer surface 21o of the columnar section 21) and intersects with the end surface 39 of the columnar section 21 on the other axial side. The third plane 33 has a fan shape.

The fourth plane 34 is the other axial end of the column 21, that is, the tip of the column 21 (claw 25), and is formed on the outside of the column 21 (claw 25) in the radial direction. ing. The fourth plane 34 is a plane that intersects with the outer circumferential surface of the retainer 14 (radially outer surface 21o of the columnar section 21) and intersects with the end surface 39 of the columnar section 21 on the other axial side. The fourth plane 34 has a fan shape.

When the ball bearing 18 (inner ring 17) rotates among the third plane 33 and the fourth plane 34, the balls 13 come into point contact with a plane located on the front side in the rotation direction. Further, when the ball bearing 18 (inner ring 17) rotates, the balls 13 may come into point contact with the first plane 31 in addition to making point contact with the third plane 33 or the fourth plane 34. While the ball bearing 18 (inner ring 17) is rotating, the balls 13 are not in contact with the concave surface 30 and are in contact with at least one of the first plane 31, the third plane 33, and the fourth plane 34. Make point contact with a plane. The concave surface 30 is not limited to a shape along the virtual spherical surface K, but may be any concave shape that does not contact the ball 13.

In FIG. 3, when the retainer 14 is displaced to one side in the axial direction, at least one of the third plane 33 and the fourth plane 34 comes into point contact with the balls 13. When the retainer 14 is displaced to the other side in the axial direction, the first plane 31 comes into point contact with the balls 13. When the cage 14 is displaced radially outward (towards the outer ring 11 ), the first plane 31 comes into point contact with the balls 13 . When the retainer 14 is displaced radially inward (towards the inner ring 17 ), at least one of the third plane 33 and the fourth plane 34 comes into point contact with the balls 13 . The concave surface 30 is a surface that does not contact the ball 13.

The retainer 14 does not contact the inner ring 17 and the outer ring 11 even if it is displaced in the radial and axial directions. Instead, when the retainer 14 is displaced radially and axially, it makes point contact with the balls 13 on at least one of the first plane 31, the third plane 33, and the fourth plane 34. Further, even if the retainer 14 is displaced in at least one of the radial direction and the axial direction, the balls 13 do not contact the concave surface 30, and the balls 13 are not in contact with the first plane 31, the third plane 33, and the fourth plane 34. Point contact is made with at least one of the planes.

In the case of the wheel bearing shown in FIG. 1, each part is elastically deformed when the vehicle turns, and as a result of this, the contact angle of the ball bearing 18 may change by, for example, about plus or minus 2 degrees. In this way, even if the contact angle (the angle of the straight line Q) changes by plus or minus 2 degrees, each of the first plane 31, third plane 33, and fourth plane 34 can make point contact with the ball 13. It is set to be spacious.

FIG. 8 is a diagram showing modification example 1 of the cage 14. The pocket surface 23 of the retainer 14 shown in FIG. 8 has a first plane 31, a third plane 33, and a fourth plane 34 similar to the embodiments shown in FIGS. 5 and 6. Furthermore, the retainer 14 has a second plane 32 . The second plane 32 is formed in the annular portion 20 (the other axial surface of the annular portion 20). The second plane 32 is formed on the outer side of the annular portion 20 in the radial direction. As shown in FIG. 8, the second plane 32 is a plane, and a circular plane with a portion missing. The second plane 32 is provided on the radially outer side of the first plane 31 along the pocket surface 23, and is a plane that intersects with the outer circumferential surface 20o of the retainer 14 (annular portion 20). The first plane 31 and the second plane 32 are provided apart from each other with a part of the concave surface 30 interposed therebetween. When the retainer 14 is displaced to the other side in the axial direction, the second plane 32 can make point contact with the balls 13.

When the ball 13 is brought into point contact with the third plane 33 and the fourth plane 34 and the ball 13 is brought into contact with a region of the pocket surface 23 on the radial outer side of the annular portion 20, the contact position is included. A second plane 32 is set in the range.
Furthermore, as another contact mode, when the ball 13 is brought into point contact with the first plane 31 and the ball 13 is brought into contact with a region outside the annular portion 20 in the radial direction of the pocket surface 23, the contact A second plane 32 is set in a range including the position. In this case, the ball 13 contacts the first plane 31 and the second plane 32 at two points.
The retainer 14 shown in FIG. 8 is suitable when the pocket surface 23 is relatively large compared to the balls 13. When the ball bearing 18 rotates, the balls 13 are able to make point contact with the second plane 32 .

In Modification 1, the first plane 31 and the second plane 32 are provided apart from each other with a part of the concave surface 30 interposed therebetween.
However, the present invention is not limited thereto, and the first plane 31 and the second plane 32 may be formed as a single plane. In other words, the first plane 31 includes the second plane 32, and the first plane 31 is a plane formed from the radially inner side to the radially outer side. The first plane 31 intersects with an extension of the rotation axis (rotation center line S) of the ball 13 on the radially inner side of the other axial surface of the annular portion 20 .

FIG. 9 is a diagram showing a second modification of the cage 14. The pocket surface 23 of the retainer 14 shown in FIG. 9 has a first plane 31, a third plane 33, and a fourth plane 34 similar to the embodiments shown in FIGS. 5 and 6. Furthermore, the retainer 14 has a second plane 32 similar to the first modification. Furthermore, the retainer 14 has a fifth plane 35 and a sixth plane 36. The fifth plane 35 is provided on one side of the pocket surface 23 in the circumferential direction. The fifth plane 35 is provided in a range of the pocket surface 23 that includes a position in front of the ball 13 in the rolling direction. The sixth plane 36 is provided on the other side of the pocket surface 23 in the circumferential direction. The sixth plane 36 is provided in a range of the pocket surface 23 that includes a rear position in the rolling direction of the ball 13.

The retainer 14 shown in FIG. 9 is suitable when the pocket surface 23 is relatively large compared to the balls 13. When the ball bearing 18 rotates, the balls 13 can make point contact with the fifth plane 35, and even if the balls 13 advance or lag, the balls 13 can make point contact with the sixth plane 36. becomes possible.

Still another form of the retainer 14 is not a crown-shaped retainer having the annular portion 20 only on one side in the axial direction as shown in FIGS. 4 and 9, but on both sides in the axial direction as shown in FIG. The cage 14 may have annular portions 20a and 20b. Also in the retainer 14 shown in FIG. 10, the pocket surface 23 includes a concave surface 30, a first plane 31 formed on one side in the axial direction of the pocket center P and capable of contacting the balls 13, and a pocket center P. It has a third plane 33 and a fourth plane 34 which are formed on the other side of P in the axial direction and can come into contact with the ball 13.

In the form shown in FIG. 10, the first plane 31 is provided on the other axial surface of the first annular portion 20a, and can make point contact with the ball 13. The first plane 31 intersects with an extension of the rotation axis (rotation center line S) of the ball 13. In the form shown in FIG. 10, the first plane 31 is perpendicular to the extension line of the rotation axis (rotation center line S) of the ball 13. The third plane 33 is formed on the other side of the pocket center P in the axial direction. Specifically, the third plane 33 is provided in a region including the boundary between the second annular portion 20b and the first columnar portion 21a, and can make point contact with the ball 13. The fourth plane 34 is formed on the other side of the pocket center P in the axial direction. Specifically, the fourth plane 34 is provided in a region including the boundary between the second annular portion 20b and the second columnar portion 21b, and can make point contact with the ball 13. The concave surface 30 is a surface that does not come into contact with the ball 13. The concave surface 30 may have a shape along an imaginary spherical surface K having the same center as the ball 13 to be held, but may be a concave curved surface other than such a shape.

As described above, in the ball bearing 18 of each of the above embodiments (FIG. 4, FIG. 8, FIG. 9, and FIG. 10), the balls 13 are arranged on the first plane 31, the third plane 33, and the fourth plane 34. It is held in the holder 14 in point contact with at least one plane. According to such a ball bearing 18, the balls 13 are held in the retainer 14 by contacting at least one of the first plane 31, the third plane 33, and the fourth plane 34 of the pocket surface 23. In this case, the ball 13 makes point contact with the plane at the contact position. Therefore, at the contact position, a lubricant such as grease is likely to be present between the pocket surface 23 (the plane) and the ball 13, making it possible to reduce the rotational resistance of the ball bearing 18.

In the ball bearings 18 of each of the above embodiments (FIGS. 4, 8, 9, and 10), the retainer 14 does not contact the inner ring 17 and the outer ring 11 even if it is displaced in the radial direction and the axial direction. Instead, when the retainer 14 is displaced radially and axially, it makes point contact with the balls 13 on at least one of the first plane 31, the third plane 33, and the fourth plane 34. For this reason, each type of ball bearing 18 is not a raceway-guided bearing in which the cage 14 is positioned by the outer ring 11 or the inner ring 17, but a rolling element in which the cage 14 is positioned by the balls 13 in the radial and axial directions. It becomes a bearing for guidance. Even in the case of a bearing guided by rolling elements, a configuration is obtained in which the balls 13 make point contact with at least one of the first plane 31, the third plane 33, and the fourth plane 34.

In the ball bearing 18 of each of the above embodiments (FIGS. 4, 8, 9, and 10), the balls 13 are not in contact with the concave surface 30, and the balls 13 are in contact with the first plane 31, the third plane 33, and the fourth plane. 34, point contact is made with at least one plane. If the balls 13 and the concave surface 30 come into contact, they will come into contact within an elliptical area, approaching surface contact, and the shear resistance of the lubricant will likely increase. However, according to each of the ball bearings 18 described above, since the balls 13 are in point contact with the pocket surface 23 (the plane), the shear resistance of the lubricant is reduced, and the rotational resistance of the ball bearing 18 can be reduced. It becomes possible.

In the case of the ball bearing 18 of each form described above, the first plane 31 intersects (perpendicularly intersects) with the extension line of the rotation axis (rotation center line S) of the balls 13. At a point on the outer surface of the ball 13 that intersects with the rotation axis of the ball 13, the circumferential speed (rotation speed) of the ball 13 becomes slow (approaches 0). Therefore, on the first plane 31, it is possible to further reduce the shear resistance of the lubricant due to contact with the balls 13. Although the third plane 33 and the fourth plane 34 do not intersect with the rotation axis (rotation center line S) of the ball 13, they are located at the other end of the pocket surface 23 in the axial direction of the column 21. It is formed in a range that includes the position closest to the rotation axis. This allows the ball 13 to come into contact with the third plane 33 and the fourth plane 34 at the position where the circumferential speed (rotation speed) of the ball 13 is as small as possible. be.

In the embodiment described above, a case has been described in which the ball bearing of the present invention is included in the bearing device 10 for a wheel, but the ball bearing of the present invention may be used for other purposes, such as an outer ring, an inner ring, a plurality of balls, Any ball bearing may be used as long as it has a retainer for holding these balls. The pocket surface of the retainer is configured as in each of the above embodiments.

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, and includes all modifications within the scope of equivalents to the configurations described in the claims.

11 Outer ring 13 Ball 14 Cage 17 Inner ring 18 First ball bearing (ball bearing)
20 Annular part 20a, 20b Annular part 21 Pillar part 21a First pillar part 21b Second pillar part 22 Pocket 23 Pocket surface 24 Pillar body 25 Claw part 25a First claw part 25b Second claw part 30 Concave surface 31 First plane 32 Two planes 33 Third plane 34 Fourth plane B Distance D Diameter K Virtual spherical surface P Pocket center S Rotation center line (rotation axis)

Claims (4)

comprising an outer ring, an inner ring, a plurality of balls that are rotatably provided between the outer ring and the inner ring, and a cage that holds the plurality of balls,
The retainer is
an annular portion located on one side of the ball in the axial direction;
a plurality of pillar portions extending from the annular portion to the other side in the axial direction;
A space between two circumferentially adjacent columnar parts on the other axial side of the annular part is a pocket that accommodates one of the balls,
The pocket has a pocket surface facing the ball,
When the center of the ball accommodated in the pocket is defined as the pocket center,
The pocket surface is
concave surface;
a first plane formed on one axial side of the pocket center and capable of contacting the ball;
A third plane that is formed on the other side in the axial direction of the pocket center in one of the two circumferentially adjacent pillars and that is capable of contacting the ball;
a fourth plane that is formed on the other side in the axial direction of the pocket center in the other second column section of the two circumferentially adjacent column sections and that is capable of contacting the ball;
has
the first plane intersects with an extension of the axis of rotation of the ball;
The ball is held in the holder in point contact with at least one plane among the first plane, the third plane, and the fourth plane,
ball bearings. The retainer does not contact the inner ring and the outer ring even if it is displaced in the radial direction and the axial direction,
2. The retainer according to claim 1, wherein when displaced in the radial and axial directions, the retainer makes point contact with the balls on at least one of the first plane, the third plane, and the fourth plane. Ball bearings listed. 3. The ball is in point contact with at least one of the first plane, the third plane, and the fourth plane without contacting the concave surface. ball bearings. The first column portion has a first claw portion at the other end in the axial direction, and the second column portion has a second claw portion at the other end in the axial direction,
The distance between the first claw part and the second claw part is smaller than the diameter of the ball,
the third plane is formed on the first claw part,
The ball bearing according to any one of claims 1 to 3, wherein the fourth plane is formed in the second claw portion.

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