JP2002115721A - Ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing in which an acoustic characteristic is not deteriorated by a washing, and an sufficient washing effect is easily obtained with a little vibration of a retainer. SOLUTION: This ball bearing 1 is provided with an inner ring 2 provided with an inner ring track surface 2a; an outer ring 3 provided with an outer ring track surface 3a; a plurality of balls 4 rollably arranged between both track surfaces 2a, 3; and a retainer 5 for retaining a plurality of balls 4 between both track surfaces 2a, 3a. A plurality of pockets with which the retainer 5 is provided are constituted by a first pocket P1 and a second pocket P2. The first pocket P1 and the second pocket P2 are arranged at different positions by a deviation amount D in an axial direction and are alternately arranged in a continuous direction of the retainer 5. In the case where a previous pressure is not axially applied to the ball bearing 1, the balls 4 are not urged to the inner ring raceway surface 2a and the other ring raceway surface 3a. In the case where the previous pressure is axially applied to the ball bearing 1, a pocket gap C is provided such that the balls 4 are urged to the both raceway surfaces 2a, 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bearing, and more particularly to a hard disk drive (hereinafter referred to as HDD) and a floppy disk drive (hereinafter referred to as FDD).
), Ball bearings, HDDs, and the like that are preferably used for a rotary support portion in information equipment such as a video tape recorder (VTR) and a digital audio tape recorder (DAT).
The present invention relates to a ball bearing suitably used for a swinging motion part in a swing arm which is a part of a component such as an FDD, or a ball bearing suitably used for a cooling fan motor or the like.

[0002]

2. Description of the Related Art As a conventional ball bearing as described above, for example, Japanese Unexamined Patent Publication No.
No. 512 and JP-A-11-193821. First, a ball bearing described in JP-A-10-19039 will be described. This ball bearing includes a retainer in which two types of pockets are alternately arranged in a circumferential direction. The two types of pockets have different axial positions in the retainer.

In this ball bearing, the difference (deviation) between the axial positions of the two types of pockets is large, so that the balls are pressed axially against the inner ring raceway surface and the outer ring raceway surface (depending on the type of pocket). , The pressing direction is the opposite direction), and the preload is applied. Since the ball is pressed against the inner ring raceway surface and the outer ring raceway surface, the movement of the ball in the axial direction is suppressed, and it is possible to prevent the occurrence of abnormal cold noise caused by the movement of the ball.

Next, a ball bearing described in Japanese Utility Model Laid-Open Publication No. 4-34512 will be described. The ball bearing includes a retainer that is biased in at least a part of a circumferential direction toward at least one of radially inward and outward directions. As a result, the clearance between the cage and the rolling element, or the clearance between the cage and the raceway surface of either the inner or outer ring becomes negative,
Since movement of the retainer in the radial direction is suppressed, excessive vibration of the retainer is prevented, and generation of noise is prevented.

Next, the ball bearing described in Japanese Patent Application Laid-Open No. H11-193821 will be described with reference to the drawings of the publication and the reference numerals assigned to the drawings. The cage 4 provided on this ball bearing has a plurality of pockets 5, of which at least one pocket 5 has a radial center O 2.
Is the dimension S on one side in the axial direction from the center line Y-Y of the bearing track.
At least one other pocket 5 offset by one
Is located on the other side in the axial direction from the center line YY of the bearing track by a distance S2. The other center O1 of the pocket 5 is located on the center line of the bearing track.

[0006] With such a configuration, when the cage 4 is incorporated into the ball bearing, the radial center O2 is aligned with the center line Y- of the bearing track.
The ball 3 is in contact with the pocket bottom 6 in the pocket 5 which is located on the one side in the axial direction from Y by the dimension S1. Further, in the pocket 5 in which the radial center O3 is shifted from the center line Y-Y of the bearing track on the other side in the axial direction by the dimension S2, the ball 3 is in contact with the pocket opening 7.

The cage 4 is positioned in the axial direction with respect to the ball 3 by the contact between the ball 3 and the pocket 5, so that the cage 4 rattles in the axial direction during rotation of the bearing, that is, retains. The whirling of the vessel is reduced, and the noise and vibration when the bearing rotates are reduced.

[0008]

Since the information devices such as HDDs and devices such as cooling fan motors are required to have high quietness, bearings used in the devices are also required to have excellent acoustic characteristics. ing. Therefore, before the grease is sealed in the bearing, the bearing may be sufficiently cleaned such as ultrasonic cleaning.

However, in the above-mentioned conventional ball bearings, a preload is always applied,
Since the ball is pressed against the raceway surface, there is a problem that fretting occurs during ultrasonic cleaning, and the acoustic characteristics of the bearing may be degraded. Further, in a state where the ball is pressed against the raceway surface, there is a problem in that foreign substances caught between the ball and the raceway surface are difficult to fall, and it is difficult to obtain a sufficient cleaning effect.

Therefore, the present invention solves the above-mentioned problems of the conventional ball bearing, so that the acoustic characteristics are not deteriorated by washing, a sufficient washing effect is easily obtained, and the cage is easily obtained. An object of the present invention is to provide a ball bearing with less vibration.

[0011]

In order to solve the above problems, the present invention has the following arrangement. That is, the ball bearing of the present invention includes an inner ring having an inner ring raceway surface, an outer ring having an outer ring raceway surface, and a plurality of rolling elements arranged to be rollable between the inner ring raceway surface and the outer ring raceway surface. A ball bearing comprising: a moving body; and a retainer that retains the plurality of rolling elements between the inner raceway surface and the outer raceway surface. Consisting of less than half of the number of the first pocket and the remaining second pocket, and the first pocket and the second pocket are arranged at different positions in the retainer in the axial direction,
When no preload is applied to the ball bearing in the axial direction, the rolling elements are not pressed against the inner raceway surface and the outer raceway surface, and preload is applied to the ball bearing in the axial direction. In this case, a pocket clearance is provided so that the rolling element is pressed on at least one of the inner raceway surface and the outer raceway surface.

With such a configuration, since the rolling element has play in the axial direction due to the pocket clearance, the ball bearing is not attached to a device or the like and preload is applied in the axial direction. In the absence state, the cage and the rolling elements are not restricted to each other, and the rolling elements are not pressed against the inner raceway surface and the outer raceway surface.

Therefore, when the ball bearing is cleaned by ultrasonic cleaning or the like, there is a low possibility that fretting occurs on the raceway surface and the acoustic characteristics of the ball bearing are deteriorated. Further, since the rolling elements are not pressed against the two raceway surfaces, foreign matter is less likely to be caught between the rolling elements and the two raceway surfaces. Therefore, the foreign matter is easily washed, and a sufficient washing effect is easily obtained.

In a state where the ball bearing is incorporated in a device such as a spindle motor or the like and a preload is applied to the ball bearing in the axial direction, the retainer and the rolling element are restrained from each other. The rolling element is pressed against at least one of the inner raceway surface and the outer raceway surface. For this reason, the vibration of the cage is suppressed, and the equal distribution of the rolling elements is also prevented from being shifted by the pocket clearance.

It is preferable that the difference between the positions of the first pocket and the second pocket in the axial direction be equal to or less than the sum of the pocket clearance and 1/2 of the axial internal clearance. Then, in a state where no preload is applied to the ball bearing in the axial direction, the rolling elements are less likely to be pressed against the two raceway surfaces, and in a state where the preload is applied, the two raceways The rolling element is more likely to be pressed against the surface, and as a result, the above-described effects are more likely to be obtained.

Further, it is preferable that the retainer is a ball guide retainer. Then, since the retainer does not contact the inner ring and the outer ring but contacts only the rolling element,
When a preload is applied to the ball bearing in the axial direction, the retainer and the rolling element are easily restrained from each other, and the above-described effects are easily obtained. Further, it is preferable that the first pockets and the second pockets are alternately arranged in the retainer in a circumferential direction (a continuous direction of the retainer that is continuous in the circumferential direction). Then, when a preload is applied to the ball bearing in the axial direction, the mutual restraint between the retainer and the rolling elements is performed uniformly as a whole. This is preferable because it is easy to effectively suppress the vibration and the displacement of the rolling elements.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a ball bearing according to the present invention will be described below in detail with reference to the drawings. FIG.
1 is a cross-sectional view illustrating a configuration of a ball bearing 1 according to a first embodiment. FIG. 2A is a partial cross-sectional view of the ball bearing 1 when no preload is applied, and FIG. 2B illustrates a state of the retainer 5 and the ball 4 when no preload is applied. FIG. FIG. 3A is a partial cross-sectional view of the ball bearing 1 when a preload is applied, and FIG. 3B illustrates a state of the retainer 5 and the ball 4 when a preload is applied. FIG. In FIG. 2, the retainer 5 is not shown. In FIGS. 1 to 3, the same or corresponding parts are denoted by the same reference numerals.

The ball bearing 1 of the first embodiment has an inner race 2 having an inner raceway surface 2a on the outer peripheral surface and an outer raceway surface 3a on the inner peripheral surface.
, A plurality of balls 4 rotatably disposed between the inner raceway surface 2a and the outer raceway surface 3a, and a plurality of balls between the inner raceway surface 2a and the outer raceway surface 3a. A cage 5 for holding the ball bearings 4 at equal intervals over the circumferential direction of the ball bearing 1;
Shields 6, 6 attached to the inner peripheral surfaces of both ends of the
It has.

The cage 5 is a crown-shaped cage, and has an annular portion 5.
a and a plurality of elastic members 5b protruding from one surface in the axial direction of the annular portion 5a. A concave pocket P for accommodating the ball 4 is formed between a pair of adjacent pairs 5b, 5b.
The pocket 4 holds the ball 4. The retainer 5 is a ball guide retainer that does not contact the inner ring 2 and the outer ring 3 but contacts only the ball 4.

There are two types of pockets P, a first pocket P1 and a second pocket P2, which are arranged at different positions in the holder 5 in the axial direction. This will be described in more detail with reference to FIG. 2B and FIG. FIG. 2B is a partial development view of the retainer 5 of the ball bearing 1 of the first embodiment and the ball 4 held by the retainer 5 viewed from the radial direction. FIG. 7 is a partial development view of the retainer 15 of the conventional ball bearing and the ball 14 held by the retainer 15 viewed from the radial direction.

The pockets P3 provided in the cage 15 of the conventional ball bearing have the same axial center position, and therefore, the axial center of the balls 14 housed in the pockets P3. The positions are also the same position (as shown in FIG. 7, all the center positions are on the same straight line). However, in the ball bearing 1, as shown in FIG.
The center position of the first pocket P1 is the annular portion 5 of the retainer 5.
The center position of the second pocket P2 is located closer to one of the holders 5b. That is, the center positions of the pockets P1 and P2 are shifted in the axial direction, and the shift amount is D. Therefore, due to the axial displacement of the first pocket P1 and the second pocket P2, the center position of the ball 4 is also shifted by D in the axial direction. And this deviation amount D
Is equal to or less than the sum of a pocket clearance C described later and の of the axial internal clearance. In addition, the first pocket P
The first and second pockets P2 are alternately arranged in a continuous direction of the retainer 5 (a circumferential direction of the annular retainer 5).

First pocket P1 and second pocket P2
Has a pocket clearance C between itself and the ball 4. The pocket clearance C is a clearance generated between the ball 4 and the bottom surface of the pocket P when the ball 4 is in contact with the two 5b (see FIG. 3B). As a result, the ball 4 has play in the axial direction. That is, as shown by a broken line in FIG. 2A, the ball 4 can move in the axial direction by A (the amount of play A).

In a state where the ball bearing 1 is not attached to a device or the like and no preload is applied in the axial direction,
Due to the play, the ball 4 is not pressed by the retainer 5, and the movements of the ball 4 and the retainer 5 are not restricted to each other. That is, the ball 4 and the retainer 5 are not restricted to each other,
The ball 4 is not pressed by the inner raceway surface 2a and the outer raceway surface 3a.

A case where the ball bearing 1 is attached to a device or the like and a state where a preload is applied in the axial direction will be described with reference to FIG. FIG. 3B is a partial development view of the retainer 5 and the ball 4 held by the retainer 5 as viewed from the radial direction. When the preload is applied in the axial direction, the ball 4 comes into contact with the two wheels 2 and 3, and the ball 4 is pushed in the contact angle direction. As a result, all the balls 4 are arranged on a plane perpendicular to the axial direction along the inner raceway surface 2a and the outer raceway surface 3a. That is, the center positions of the pockets P1 and P2 are shifted in the axial direction as shown by the dashed line, but the center positions of the balls 4 are the same as shown by the broken lines.

At this time, the ball 4 in the first pocket P1 whose center position is located near the annular portion 5a is
5b, and is pressed against the inner surface of the 5b. On the other hand, the ball 4 in the second pocket P2 whose center position is located closer to the 5b is the second pocket P2.
And is pressed against the bottom surface of the second pocket P2.

This will be further described with reference to FIG. FIG. 4 is a conceptual diagram showing in which direction each ball 4 is pressed when only the balls 4 are viewed from the axial direction.
Those marked with “x” on the ball 4 are pressed rearward (rear side) in FIG. 4, and those marked with “•” are pressed forward (front side) in FIG. 4. Is shown. Since the first pocket P1 and the second pocket P2 are alternately arranged in the continuous direction of the retainer 5, the direction in which the ball 4 is pressed is also alternated.

In such a ball bearing 1, when no preload is applied in the axial direction, the ball 4 and the retainer 5 are not restrained from each other due to the play, and the ball 4 is in contact with the inner raceway surface 2a and the inner ring raceway surface 2a. It is not pressed by the outer raceway surface 3a. Therefore, even if such a ball bearing 1 is subjected to cleaning such as ultrasonic cleaning, fretting occurs on the inner raceway surface 2a and the outer raceway surface 3a at that time, and the acoustic characteristics of the ball bearing 1 may be deteriorated. Poor. Further, since the ball 4 is not pressed against the inner raceway surface 2a and the outer raceway surface 3a, foreign matter is less likely to be caught between the ball 4 and the inner raceway surface 2a and the outer raceway surface 3a. Therefore, the foreign matter is easily washed, and a sufficient washing effect is easily obtained.

When the ball bearing is assembled in a device such as a spindle motor or the like and a preload is applied to the ball bearing in the axial direction, the ball 4 is pressed by the retainer 5 as described above (the first pocket). P1 and the second pocket P2 are pressed in the direction opposite to the direction of displacement). Then, the retainer 5 and the ball 4 are restrained from each other by the elasticity of the retainer 5, and the movement of the ball 4 and the retainer 5 is regulated. The ball 4 is pressed against the inner raceway surface 2a and the outer raceway surface 3a.

As a result, the movement of the retainer 5 in the axial direction and the radial direction is suppressed, so that the vibration of the retainer 5 is suppressed. Also, due to the mutual constraint between the retainer 5 and the ball 4,
The displacement of the balls 4 evenly by the pocket clearance C can be suppressed. For this reason, the non-rotationally synchronized vibration component (NRRO) of the ball bearing 1 can be suppressed, so that if the ball bearing 1 is used for an information device such as an HDD, an information device with excellent performance can be obtained. it can.

Further, since the axial displacement D between the first pocket P1 and the second pocket P2 is equal to or less than the sum of the pocket clearance C and 1/2 of the axial internal clearance, the ball bearing 1 When the preload is not applied in the direction, the balls 4 are less likely to be pressed against the inner raceway surface 2a and the outer raceway surface 3a, and when the preload is applied, the inner raceway surface 2a and the outer raceway surface 2a. As a result, the ball 4 is more likely to be pressed by 3a, and as a result, the above-described effects (suppression of vibration of the retainer 5 and suppression of displacement of the ball 4) are easily obtained.

The amount of deviation D varies depending on the ratio between the radius of curvature of the inner raceway surface 2a and the outer raceway surface 3a and the diameter of the ball 4, the radial internal clearance, and the pocket clearance C. The size is about 10%. Further, since the retainer 5 is a ball guide retainer, when the ball bearing 1 is preloaded in the axial direction, the retainer 5 and the ball 4 are easily restrained from each other, and the above-mentioned effect is obtained. Cheap.

Further, since the first pockets P1 and the second pockets P2 are alternately arranged in the continuous direction of the cage 5, when the ball bearing 1 is preloaded in the axial direction, the cage P Since the mutual restraint between the ball 5 and the ball 4 is performed uniformly as a whole, the vibration of the cage 5 can be suppressed and the ball 4 can be restrained.
Is effectively suppressed. next,
A ball bearing according to the second embodiment will be described. The configuration of the ball bearing is substantially the same as the configuration of the ball bearing 1 of the first embodiment except that the shape of the pocket P is different. Therefore, the description of the same parts will be omitted, and only different parts will be described. In the description, FIGS. 1 and 2A and FIG. 3A are referred to together with FIGS. FIG.
FIG. 6 is a partial development view of a retainer 5 of the ball bearing according to the second embodiment and the ball 4 held by the retainer 5 viewed from a radial direction;
(A) when no preload is applied in the axial direction, (b)
Is a case where a preload is applied in the axial direction. FIG. 6 is a conceptual diagram showing in which direction each ball 4 is pressed when only the balls 4 are viewed from the axial direction. In addition,
5 and 6, the same or corresponding parts as those in FIG. 2B are denoted by the same reference numerals.

The first pocket P1 and the second pocket P2 provided in the retainer 5 have inner surfaces in the continuous direction of the retainer 5 (the circumferential direction of the annular retainer 5; Direction) is a major axis, and a minor axis is the diameter in the axial direction (vertical direction in FIG. 5). That is, the inner surface has a shape such that a space surrounded by the inner surface has a substantially elliptical shape. A concave portion 8 is provided on the bottom surface of the pocket P to form a “runaway portion” of the ball 4 on the bottom surface of the pocket.

As shown in FIG. 6, the first pockets P1 and the second pockets P2 are alternately arranged every two in the continuous direction of the retainer 5. That is, the first pocket P1, the first pocket P1, the second pocket P2, the first pocket P1, the first pocket P1, the second pocket P2,.
This is an arrangement pattern of the pocket P. The pocket clearance C in the case where the shape of the pocket P is as described above.
The position of the ball 4 when the ball 4 is in contact with the two 5b (shown by a solid line in FIG. 5) as shown in FIG.
Means a difference from the position when the position is located on the side of the annular portion 5a (shown by a broken line in FIG. 5).

With such a configuration, the ball bearing of the second embodiment has the same effect as the ball bearing 1 of the first embodiment. Note that the first and second embodiments show examples of the present invention, and the present invention is not limited to these embodiments. For example, the present invention can be applied to various ball bearings such as a deep groove ball bearing, an angular ball bearing, and a thrust ball bearing. In the above-described embodiment, the cage adopts a crown type cage. However, there is no problem with other types of cages. For example, a shape holder, a waveform holder, a matching holder, and the like.

Further, examples of the material of the cage include a metal such as steel and a resin. As the resin, for example,
Polyamide resin such as nylon 66 and nylon 46, PT
Fluorine resins such as FE and ETFE; ether ketone resins such as polyether ether ketone resin (PEEK); polyether sulfone resin (PES); polyoxymethylene resin (POM); polybutylene terephthalate resin (PBT); Type polyphenylene sulfide resin (L-PPS) and the like.

Fibers may be added to these resins in order to impart strength. Examples of preferably used fibers include glass fibers, carbon fibers, aramid fibers, and various whiskers. The fiber content is
It is appropriately selected in consideration of moldability, assemblability, and the like in addition to the strength of the cage. Usually, it is 5 to 40% by weight. Further, the arrangement pattern of the first pocket P1 and the second pocket P2 is as follows.
The pattern alternately arranged in the continuous direction of the retainers 5 is most preferable for the above-mentioned reason, but is not limited to this pattern. Also, the number of balls 4 is not particularly limited.

The material of the ball 4 may be steel or ceramic. Further, a contact-type or non-contact-type seal may be attached instead of the shield 6, or the shield 6 may not be attached.

[0039]

As described above, in the ball bearing of the present invention, the acoustic characteristics are not deteriorated by washing, and a sufficient washing effect is easily obtained. Further, the vibration of the cage is small.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a ball bearing according to a first embodiment.

FIG. 2 is a partial cross-sectional view and a partially developed view showing a state of the ball bearing in a case where no preload is applied in the ball bearing of the first embodiment.

FIG. 3 is a partial sectional view and a partially developed view showing a state of the ball bearing when a preload is applied in the ball bearing of the first embodiment.

FIG. 4 is a conceptual diagram showing a state of a ball when a preload is applied in the ball bearing of the first embodiment.

FIG. 5 is a partially developed view showing a state of a cage and balls of the ball bearing according to the second embodiment.

FIG. 6 is a conceptual diagram showing a state of a ball when a preload is applied in the ball bearing of the second embodiment.

FIG. 7 is a partial development view showing a state of a cage and balls of a conventional ball bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ball bearing 2 Inner ring 2a Inner ring raceway surface 3 Outer ring 3a Outer ring raceway surface 4 Ball 5 Cage A Play amount C Pocket clearance D Shift amount P pocket P1 First pocket P2 Second pocket

Claims (1)

[Claims] An inner ring having an inner raceway surface, an outer ring having an outer raceway surface, a plurality of rolling elements rotatably disposed between the inner raceway surface and the outer raceway surface; A cage for holding the plurality of rolling elements between the inner raceway surface and the outer raceway surface, wherein the plurality of pockets of the cage is one or more and half of the total number of pockets. The following first pocket and the remaining second pocket are configured, and the first pocket and the second pocket are arranged at different positions in the retainer in the axial direction. When the preload is not applied, the rolling elements are not pressed against the inner raceway surface and the outer raceway surface, and when the ball bearing is preloaded in the axial direction, the inner raceway is At least one of the outer raceway surface and the outer raceway surface. Wherein such rolling element is pressed, a ball bearing, characterized in that a pocket clearance.