阅读说明：本技术 多列推力滚珠轴承 (Multi-row thrust ball bearing ) 是由 迫田裕成 菊池文 千原佑太 于 2020-02-14 设计创作，主要内容包括：本发明提供一种负载容量大且能够实现薄壁化,并且还能够负载径向载荷的多列推力滚珠轴承。一对滚道圈(21、22)在相互对置的面上具有沿径向设置的多列滚道槽(23A、23B)。保持架(40)具有在兜孔(41)的开口的周缘凸状地突出而成且仅在保持架的周向上对置配置的爪状突起(42)。爪状突起(42)的径向的最大宽度(W)比滚道槽(23)的径向的最大宽度(L)小。(The invention provides a multi-row thrust ball bearing which has large load capacity, can realize thin wall and can load radial load. The pair of raceway rings (21, 22) have a plurality of rows of raceway grooves (23A, 23B) provided in the radial direction on the surfaces facing each other. The cage (40) has claw-shaped projections (42) that protrude convexly from the peripheral edge of the opening of the pocket (41) and are arranged facing each other only in the circumferential direction of the cage. The maximum width (W) of the claw-shaped protrusion (42) in the radial direction is smaller than the maximum width (L) of the track groove (23) in the radial direction.)

1. A multi-row thrust ball bearing is characterized by comprising:

a pair of raceway rings that are formed in a circular ring shape and are arranged so as to be axially separated from each other;

a plurality of balls arranged between the pair of raceway rings so as to be capable of rolling; and

a cage disposed between the pair of raceway rings and having a plurality of pockets that hold the plurality of balls at predetermined intervals,

the pair of raceway rings have a plurality of rows of raceway grooves provided in the radial direction on the surfaces opposed to each other,

the retainer has claw-like projections which project convexly from the peripheral edge of the opening of the pocket and are arranged to face each other only in the circumferential direction of the retainer,

the maximum width in the radial direction of the claw-like projection is smaller than the maximum width in the radial direction of the track groove.

2. The multi-row thrust ball bearing of claim 1,

the pockets on an outer diameter side and the pockets on an inner diameter side are circumferentially out of phase with respect to at least some of the plurality of pockets.

3. The multi-row thrust ball bearing of claim 2,

the cage has a continuous portion that continues, of the radially adjacent outer diameter side and inner diameter side pockets, the outer diameter side pocket and the inner diameter side pocket that are relatively narrowly spaced from each other.

4. The multi-row thrust ball bearing of any of claims 1 to 3,

the pockets are arranged at unequal intervals in the circumferential direction.

5. The multi-row thrust ball bearing of any of claims 1 to 4,

the pair of raceway rings has a recess portion capable of accommodating the cage.

6. The multi-row thrust ball bearing of any of claims 1 to 5,

the depth of the track groove is 20 to 30% of the diameter of the ball, and the curvature of the track groove is 50.5 to 56% of the diameter of the ball.

7. The multi-row thrust ball bearing of any of claims 1 to 6,

a ridge line formed by the track groove and a shoulder of the track groove is chamfered.

Technical Field

The present invention relates to a double row thrust ball bearing including a plurality of balls arranged in a plurality of rows in a radial direction.

Background

Conventionally, a needle thrust bearing has been used to apply a large thrust load to a bearing for an automobile. In the thrust needle roller bearing, the raceway ring is formed of a washer-shaped thin plate, so that the entire thickness can be reduced, and the needle rollers are in line contact with the raceway ring, so that the contact area is large and the load capacity is large.

On the other hand, since the balls of the thrust ball bearing are in point contact with the ball grooves, the load capacity is smaller than that of the thrust needle bearing. However, since the contact area is small, there is an advantage that friction is small and a load in the radial direction is supported to some extent.

As a thrust ball bearing, for example, patent document 1 discloses a thrust bearing retainer as follows: in order to prevent the rolling elements from falling off from the pockets of the cage, the cage has first claw portions protruding convexly from the peripheral edges of the openings of the pockets and second claw portions protruding convexly from the pocket surfaces on the inner side of the first claw portions, and has a plurality of claw-shaped protrusions having a diameter reduced from the diameter of the rolling elements.

Patent document 2 discloses a thrust ball bearing in which a plurality of rows of track grooves are provided in a radial direction on opposed surfaces of two annular races, and a plurality of balls held by a cage are arranged between the track grooves with a contact angle.

In recent years, in the field of brake actuators, mechanisms have been developed in which a rotary motion of an electric motor is converted into a linear motion by motorization to apply hydraulic pressure or press a brake disk. Although the conversion from the rotational motion to the linear motion is performed by a ball screw, a slide screw, a rack and pinion, or the like, the lead of the ball screw or the like is set to be small and the speed is reduced, so that a large thrust can be obtained with a small rotational force. In the case of using a gear drive or belt drive system for imparting rotation to a ball screw or the like, a radial load and a thrust load may be generated simultaneously in the ball screw or the like.

As a bearing for supporting such thrust, a deep groove ball bearing, a 4-point contact ball bearing, or an angular contact ball bearing, which can support both of the radial load and the thrust load, is often used. However, in order to support a large thrust load by the angular ball bearing, a preload or the like is applied to the angular ball bearing, and the structure may become complicated. In addition, when it is necessary to support a larger thrust load, both a thrust bearing having a high load capacity such as a thrust needle bearing and a radial bearing that supports a radial load are required.

Therefore, when a thrust ball bearing capable of supporting radial loads as well as supporting thrust loads is used as a support bearing for use in a brake actuator, it is desired to develop a thrust ball bearing which has a small torque, a high load capacity that contributes to an improvement in system efficiency, and a reduced thickness.

Further, in the thrust ball bearing described in patent document 1, in order to prevent the rolling elements (balls) from falling off from the pockets of the cage, the claw-like projections are provided on the peripheral edge of the pocket opening, but as shown in fig. 1(b) of patent document 1 and the like, the claw-like projections are provided on the flat surface of the cage so as to project in the circumferential direction and the radial direction of the cage, and therefore, in order to prevent the claw-like projections from interfering with the pair of raceway rings, thinning of the thrust ball bearing is limited.

In the thrust ball bearing described in patent document 2, the claw-like projections are not provided in the cage, and therefore interference between the claw-like projections and the pair of raceway rings does not become a problem, but since there are no claw-like projections for preventing the rolling elements from falling out of the pockets, it is necessary to secure the thickness of the cage to such an extent that the rolling elements do not fall out of the pockets, and therefore, in this case, the thrust ball bearing is also limited in thickness.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-223970

Patent document 2: japanese laid-open patent publication No. 2006-200677

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above problems, and an object thereof is to provide a thrust ball bearing which has a large load capacity, can be thinned, and can be loaded with a radial load.

Means for solving the problems

The above object of the present invention is achieved by the following structure (1).

(1) A multi-row thrust ball bearing is characterized by comprising:

a pair of raceway rings that are formed in a circular ring shape and are arranged so as to be axially separated from each other;

a plurality of balls arranged between the pair of raceway rings so as to be capable of rolling; and

a cage disposed between the pair of raceway rings and having a plurality of pockets that hold the plurality of balls at predetermined intervals,

the pair of raceway rings have a plurality of rows of raceway grooves provided in the radial direction on the surfaces opposed to each other,

the retainer has claw-like projections which project convexly from the peripheral edge of the opening of the pocket and are arranged to face each other only in the circumferential direction of the retainer,

the maximum width in the radial direction of the claw-like projection is smaller than the maximum width in the radial direction of the track groove.

According to this configuration, since the plurality of balls are arranged in each of the plurality of rows of track grooves, the load capacity of the thrust ball bearing is increased. Further, since the retainer includes the claw-like projections formed by projecting the peripheral edge of the opening of each pocket in a convex shape and arranged to face each other only in the circumferential direction of the retainer, and the maximum width in the radial direction of the claw-like projections is smaller than the maximum width in the radial direction of the raceway groove, the axial direction interval between the pair of raceway rings can be narrowed, and the multi-row thrust ball bearing can be made thin.

Further, a preferred embodiment of the present invention is constituted by the following configurations (2) to (7).

(2) According to the multi-row thrust ball bearing described in (1),

the pockets on an outer diameter side and the pockets on an inner diameter side are circumferentially out of phase with respect to at least some of the plurality of pockets.

According to this configuration, the inner-diameter side pockets are disposed at positions between two adjacent pockets on the outer-diameter side when viewed in the radial direction, so that the outer-diameter side pockets and the inner-diameter side pockets can be brought close to each other in the radial direction, and a large number of pockets can be formed by the cage, whereby the load capacity can be increased.

(3) According to the multi-row thrust ball bearing described in (2),

the cage has a continuous portion that continues, of the radially adjacent outer diameter side and inner diameter side pockets, the outer diameter side pocket and the inner diameter side pocket that are relatively narrowly spaced from each other.

According to this configuration, it is possible to prevent the wall between the pockets arranged close to each other in the radial direction from being damaged, and it is possible to prevent the thrust ball bearing from being damaged by the biting of the damaged pieces.

(4) The double-row thrust ball bearing according to any one of (1) to (3),

the pockets are arranged at unequal intervals in the circumferential direction.

According to this configuration, it is possible to prevent the phase difference between the pockets on the outer diameter side and the inner diameter side from decreasing, and to prevent the wall of the pocket adjacent in the radial direction from being thinned.

(5) The double-row thrust ball bearing according to any one of (1) to (4),

the pair of raceway rings has a recess portion capable of accommodating the cage.

According to this configuration, while a predetermined thickness necessary for the cage is ensured, interference between the cage and the pair of raceway rings is prevented, and the multi-row thrust ball bearing can be made thin. Further, the recessed portion formed by forming the outer diameter side edge portion and the inner diameter side edge portion can be used as a lubricant reservoir portion for lubricating the balls, thereby reducing rolling resistance of the balls and suppressing wear of the balls, the outer diameter side raceway groove, and the inner diameter side raceway groove.

(6) The double-row thrust ball bearing according to any one of (1) to (5),

the depth of the track groove is 20 to 30% of the diameter of the ball, and the curvature of the track groove is 50.5 to 56% of the diameter of the ball.

According to this structure, the jump-up of the balls is prevented, and the load capacity of the multi-row thrust ball bearing is increased.

(7) The double-row thrust ball bearing according to any one of (1) to (6),

a ridge line formed by the track groove and a shoulder of the track groove is chamfered.

According to this structure, the occurrence of the edge load due to the jumping of the balls is alleviated.

Effects of the invention

According to the double-row thrust ball bearing of the present invention, since the pair of raceway rings have the plurality of rows of raceway grooves provided in the radial direction on the surfaces facing each other, it is possible to support a load with a larger number of balls than the conventional thrust ball bearing, and it is possible to increase the load capacity of the thrust ball bearing.

Further, the retainer has claw-like projections which project convexly from the peripheral edge of the opening of the pocket and are arranged to face each other only in the circumferential direction of the retainer, and the maximum width in the radial direction of the claw-like projections is smaller than the maximum width in the radial direction of the raceway groove.

Drawings

Fig. 1 is a longitudinal sectional view of a main part of a double row thrust ball bearing according to an embodiment of the present invention.

Fig. 2 is an exploded perspective view of the multiple row thrust ball bearing shown in fig. 1.

Fig. 3 is a partially enlarged perspective view of fig. 2 surrounded by a rectangle a.

Fig. 4 is a partially enlarged perspective view of fig. 2 surrounded by a rectangle B.

Fig. 5 is a plan view of the cage showing a state in which the phases of the pockets are different on the inner diameter side and the outer diameter side.

Fig. 6 is a plan view of the cage showing a state in which radially adjacent pockets are continuously formed with each other.

Fig. 7 is a plan view of the cage showing a state in which pockets on the inner diameter side and the outer diameter side are formed at unequal intervals.

Fig. 8 is a longitudinal sectional view of a main part of a double row thrust ball bearing in which a ridge line formed by a raceway groove and a shoulder portion is chamfered.

Description of the symbols

10-row thrust ball bearing

14 concave part

21. 22 raceway ring

23 raceway groove

23A outer diameter side raceway groove (raceway groove)

23B inner diameter side raceway groove (raceway groove)

24 outer diameter side edge part

25 inner diameter side edge part

26 back side part

27 shoulder part

28 chamfered part

30 ball (Rolling element)

40 holding rack

41 pocket

42 claw-shaped protrusion

43 opening edge (opening edge)

44 continuous portion

d diameter of ball

Depth of H-shaped raceway groove

Maximum radial width of L-shaped raceway groove

Curvature of r-track groove

Maximum radial width of W-shaped claw

Detailed Description

Hereinafter, an embodiment of a double row thrust ball bearing according to the present invention will be described in detail with reference to the drawings.

As shown in fig. 1 and 2, the double-row thrust ball bearing 10 of the present embodiment includes: a pair of raceway rings 21 and 22 formed in an annular shape and arranged in parallel to each other so as to be axially separated from each other; a plurality of balls (rolling elements) 30 rollably disposed between the pair of raceway rings 21, 22; and a cage 40 having a plurality of pockets 41, the plurality of pockets 41 being capable of rolling the plurality of balls 30 and holding the plurality of balls 30 at predetermined intervals.

Here, referring to fig. 4, the pair of raceway rings 21 and 22 are formed in an annular shape, and a plurality of rows of raceway grooves 23 are provided on surfaces facing each other. The multiple-row track grooves 23 are 2-row track grooves 23, and specifically include outer diameter side track grooves 23A and inner diameter side track grooves 23B. The outer diameter side raceway grooves 23A are formed on the radially outer diameter side of the raceway rings 21, 22. The inner diameter side raceway groove 23B is formed concentrically with the outer diameter side raceway groove 23A at a position radially inward of the outer diameter side raceway groove 23A of the raceway rings 21 and 22. That is, each of the pair of raceway rings 21 and 22 includes 2 rows of raceway grooves 23 each including an outer diameter side raceway groove 23A and an inner diameter side raceway groove 23B formed concentrically.

The outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B are formed to have a radial cross-sectional shape of a substantially circular arc. As shown in fig. 1, the depth H of the track groove 23 is set to be in the range of 20% to 30% of the diameter d of the ball 30, and the ball 30 is prevented from jumping up when a radial load acts on the multiple rows of thrust ball bearings 10. The groove curvature r of the track groove 23 is set in a range of 50.5% to 56% of the diameter d of the ball 30 according to the magnitude of the input load.

Annular outer and inner diameter side edges 24 and 25 are formed on the outer and inner diameter sides of the facing surfaces of the raceway rings 21 and 22 so as to project in the axial direction. In the machining of the raceway rings 21, 22, it is necessary to grind the back surface portion 26, the outer diameter side raceway grooves 23A, and the inner diameter side raceway grooves 23B. The grinding of the back surface portion 26 requires an outer diameter side guide portion having a predetermined thickness determined according to the processing equipment, and the outer diameter side edge portion 24 is used as the outer diameter side guide portion.

Further, an annular recess 14 capable of accommodating the cage 40 is formed between the outer diameter side edge 24 and the inner diameter side edge 25 on the facing surfaces of the raceway rings 21 and 22 by the outer diameter side edge 24 and the inner diameter side edge 25. As shown in fig. 1, the cage 40 (more specifically, a flat portion of the cage 40 other than the claw-like projections 42 described later) is accommodated in the annular recess 14, whereby a predetermined thickness required for the cage 40 is secured, interference between the cage 40 and the raceway rings 21 and 22 is prevented, and the multi-row thrust ball bearing 10 is reduced in thickness.

The annular recessed portion 14 formed by the outer diameter side edge portion 24 and the inner diameter side edge portion 25 can be used as a lubricant reservoir for lubricating the balls 30, and the rolling resistance of the balls 30 is reduced, thereby suppressing wear of the balls 30, the outer diameter side raceway groove 23A, and the inner diameter side raceway groove 23B.

In the present embodiment, the pair of raceway rings 21 and 22 and the plurality of balls 30 are made of metal, and a surface hardened layer is preferably formed by nitriding or the like in order to improve durability. Further, by forming the raceway rings 21 and 22 from the same member, the groove accuracy of the outer diameter side raceway grooves 23A and the inner diameter side raceway grooves 23B of the raceway rings 21 and 22 can be improved, and the manufacturing cost can be reduced.

As shown in fig. 1 to 3, the pockets 41 of the cage 40 are formed in a plurality of rows in the circumferential direction so as to face the outer diameter side raceway grooves 23A and the inner diameter side raceway grooves 23B of the raceway rings 21 and 22. The pockets 41 are holes that pass through the cage 40 in the axial direction and rollably hold the balls 30, and a pair of claw-like projections 42 that are formed to protrude convexly in the axial direction are arranged on the peripheral edge (opening edge) 43 of the opening of each pocket 41 so as to face each other only in the circumferential direction of the cage 40. That is, the claw-like projections 42 formed on the opening edge 43 of each pocket 41 are formed only in the circumferential direction of the retainer 40, and the claw-like projections 42 are not provided in the radial direction.

As shown in fig. 3, the claw-like projections 42 formed on the opening edge 43 of each pocket 41 so as to face each other in the circumferential direction of the retainer 40 may be formed integrally with the adjacent claw-like projections 42 or may be formed separately.

As shown in fig. 1, the maximum width W in the radial direction of the claw-like projection 42 is set smaller than the maximum width L in the radial direction of the outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B (i.e., W < L). By limiting the claw-like projections 42 formed on the holder 40 to be arranged to face each other only in the circumferential direction of the holder 40 and setting the maximum width W in the radial direction of the claw-like projections 42 to be smaller than the maximum width L in the radial direction of the outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B in this way, the claw-like projections 42 can be made to enter the inside of the outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B when the multi-row thrust ball bearing 10 is assembled.

Thus, the balls 30 can be reliably held by securing the height of the claw-like projections 42, and the balls 30 can be prevented from falling out of the pockets 41. Further, even if the pair of raceway rings 21 and 22 are disposed close to each other, the claw-like projections 42 do not interfere with the raceway rings 21 and 22, and therefore, the double-row thrust ball bearing 10 can be thinned.

The cage 40 preferably has elasticity to such an extent that the claw-like projections 42 can be flexed and opened when the balls 30 are fitted into the pockets 41, and has low frictional resistance. For example, as the material, synthetic resin, such as polyamide, polyacetal, high-density polyethylene, nylon, or the like, can be used.

The double row thrust ball bearing 10 of the present embodiment increases the number of balls 30 by arranging the balls 30 in a plurality of rows on the outer diameter side and the inner diameter side of the pair of raceway rings 21 and 22, thereby increasing the load capacity while effectively utilizing the space. The number of balls 30 on the outer diameter side and the inner diameter side can be arbitrarily set.

As shown in fig. 5, at least some of the plurality of pockets are preferably arranged so that the pockets 41 on the outer diameter side and the pockets 41 on the inner diameter side are different in phase in the circumferential direction, that is, so that the pockets 41 are not aligned in phase in the circumferential direction and are shifted in phase (for example, as shown in fig. 5, the pockets are shifted in phase by 1.1 ° and 3 °). Thus, the inner-diameter side pockets 41 are arranged at positions between the 2 adjacent outer-diameter side pockets 41 as viewed in the radial direction, and the outer-diameter side pockets 41 and the inner-diameter side pockets 41 can be brought close to each other in the radial direction. As a result, more pockets can be formed in the cage, and therefore the load capacity can be further increased.

However, even if the outer diameter side pocket 41 and the inner diameter side pocket 41 are arranged with a phase shift, as shown in fig. 6, there are cases where the outer diameter side pocket 41 and the inner diameter side pocket 41 are close in phase periodically. When the phases of the pockets 41 on the outer diameter side and the inner diameter side approach, the walls that separate the adjacent pockets 41 from each other in the radial direction become thin, and therefore there is a fear that the walls may be broken and bite into during the operation of the multi-row thrust ball bearing 10.

Therefore, in the portion where the phases of the outer diameter side and inner diameter side pockets 41 are close and the wall of the pocket 41 is relatively thinner than the wall of the other portion, it is preferable to provide a continuous portion 44 in which the outer diameter side pocket 41 and the inner diameter side pocket 41 are continuous in the retainer in advance, so that the wall is prevented from being damaged during the operation of the multi-row thrust ball bearing 10. The phase difference of the pockets 41 that need to form the outer diameter side and the inner diameter side of the continuous portion 44 is, for example, 5 ° or less.

As shown in fig. 7, by setting the circumferential intervals (θ 1, θ 2) between the inner diameter side pockets 41 and the circumferential intervals (θ 3, θ 4) between the outer diameter side pockets 41 to be unequal intervals (that is, θ 1 ≠ θ 2, θ 3 ≠ θ 4), it is possible to avoid a phase difference between the outer diameter side pockets 41 and the inner diameter side pockets 41 from becoming small, and to prevent the wall separating the outer diameter side pockets 41 from the inner diameter side pockets 41 from being thinned.

As shown in fig. 8, it is preferable to form chamfered portions 28 on the ridge lines of the outer diameter side raceway groove 23A, the inner diameter side raceway groove 23B, and the respective shoulder portions 27 by turning or grinding. The fillet 28 is preferably a fillet having a radius of about 0.25 to 2 mm. Thus, even if a radial load exceeding a desired magnitude acts on the double-row thrust ball bearing 10 and the ball 30 jumps, the occurrence of a side load due to contact between the ball 30 and the shoulder 27 can be alleviated, and the life of the double-row thrust ball bearing 10 can be extended.

As described above, according to the double row thrust ball bearing 10 of the present embodiment, the plurality of balls 30 are arranged in a plurality of rows between the outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B of the pair of raceway rings 21 and 22. As a result, the load can be supported by a larger number of balls than the conventional thrust ball bearing, the load capacity of the thrust ball bearing can be increased, and both the radial load and the thrust load can be supported.

Further, the claw-like projections 42 are formed on the opening edge 43 of each pocket 41 so as to face only in the circumferential direction of the retainer 40. The maximum width W in the radial direction of the claw-like projection 42 is set smaller than the maximum width L in the radial direction of the outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B. As a result, the double-row thrust ball bearing 10 is assembled with the claw-like projections 42 accommodated in the outer diameter side raceway groove 23A and the inner diameter side raceway groove 23B, so that the distance between the pair of raceway rings 21 and 22 can be narrowed, and the double-row thrust ball bearing 10 can be thinned.

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like can be appropriately made. For example, in the present embodiment, the case where the balls are arranged in 2 rows at different positions in the radial direction has been described, but the balls may be arranged in 3 or more rows (i.e., a plurality of rows of thrust ball bearings).

While various embodiments have been described above with reference to the drawings, it is needless to say that the present invention is not limited to the examples. It is obvious that those skilled in the art can conceive various modifications and alterations within the scope of the present invention as defined by the claims. In addition, the respective components in the above embodiments may be arbitrarily combined without departing from the scope of the invention.

In addition, the present application is based on the japanese patent application filed on 14/2/2019 (japanese patent application 2019-024427), the contents of which are incorporated herein by reference.