JP2002039171A - Bearing device - Google Patents

Abstract

(57) [Problem] To provide a structure that can be easily assembled to a support shaft even if a maker does not have a special device for applying a desired preload, and to reduce the cost of articles incorporating the bearing device 1a. enable. SOLUTION: A pair of outer rings 10a, 10a are abutted against each other in the axial inner end surfaces. Further, by pressing the pair of inner rings 8, 8 in a direction approaching each other with a gap 18 interposed between the inner rings 8, 8, a cylindrical shape is formed with a desired preload applied. Is externally fixed to an intermediate portion of the sleeve 12. When assembling the bearing device 1a to the support shaft, the sleeve 12 is fitted to the support shaft by a tight fit with a slight interference without using a special device for applying a desired preload. Fix externally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The bearing device according to the present invention comprises:
For example, a spindle motor incorporated in a magnetic, optical, or magneto-optical disk drive such as a hard disk drive (HDD), a flexible disk drive (FDD), a digital video disk (DVD), and a mini disk (MD), or a swing of the HDD. It is used by being incorporated in a swing support portion of an arm or a rotation support portion of information equipment such as a motor for an IC cooling fan.

[0002]

2. Description of the Related Art For example, an HDD used as a storage device of a computer rotates a hub around a support shaft fixed to a housing fixed to a frame or the like via a bearing device to which the present invention is applied. It is freely supported. One or more hard disks formed in a ring shape are connected to and supported on the inner peripheral edge of the hub, and rotate with the hub. Since the width of the track for recording data on the hard disk is extremely narrow, this hub reduces the state in which the support shaft does not shake, that is, reduces NRRO (non-rotational shake).
It is necessary to support rotatably with high rotation accuracy. For this reason, conventionally, as a bearing device provided between the outer peripheral surface of the support shaft and the inner peripheral surface of the hub, a pair of ball bearings is combined, and a preload is applied to each ball constituting each ball bearing. Those with sufficient bearing rigidity are widely used.

FIG. 7 shows an example of such a bearing device.
This shows the one described in Japanese Patent Application Laid-Open No. H10-155843. The bearing device 1 is incorporated in an HDD motor, and is provided on the outer peripheral surface of a distal end portion and an intermediate portion of a support shaft 3 having a base end portion fixed to a center portion of a housing 2 and an inner diameter side of a hub 4. A pair of ball bearings 6, 6 are provided between the inner diameter side cylindrical portion 5 and a part of the inner peripheral surface. That is, each of these ball bearings 6 and 6 has an inner race 8 having an inner raceway 7 on the outer peripheral surface, an outer race 10 having an outer raceway 9 on the inner peripheral surface, and a space between the inner raceway 7 and the outer raceway 9, respectively. Balls 11 and 11 are provided so as to be able to roll freely. Each of these balls 11, 11 is held rotatably by a retainer 13 formed in an annular shape. The inner rings 8, 8 are externally fitted and fixed to the front end portion and the intermediate portion of the support shaft 3 by tight fitting or bonding.

On the other hand, cylindrical protruding portions 22, 22 protruding in the axial direction from the axial end surfaces of the inner rings 8, 8 are formed at one axial end of the outer rings 10, 10. ing. Then, only the portions near the butting portions of the pair of outer rings 10 and 10 are internally fixed to the inner peripheral surface of the inner diameter side cylindrical portion 5 in a state where the tip surfaces of both the protruding portions 22 and 22 abut against each other. are doing. For this purpose, a plurality of ridges 23, 23 projecting toward the inner diameter side are formed over the entire circumference on the inner peripheral surface of the axially intermediate portion of the inner diameter side cylindrical portion 5. Then, each of the protruding portions 22 and 22 is
3 and 23, they are tightly fitted to each other in a state of being bridged or fixed by bonding.

[0005] The bearing device 1 constructed as described above presses the inner races 8 and 8 in a direction approaching each other with a gap 18 interposed between the axial end faces. A desired preload is applied to the balls 11 and 11.
Then, with the preload applied in this manner, the hub 4
Does not rattle around the support shaft 3 (with high accuracy)
It is rotatably supported. A hard disk (not shown) is fixed around the outer cylindrical portion 24 provided on the outer diameter side of the hub 4 and concentrically with the outer cylindrical portion 24.

Incidentally, a spindle motor used for an information device such as an HDD needs to be rotated in a state where no blur occurs (high accuracy). For this reason, in the case of the bearing device 1 described in the above-mentioned publication shown in FIG. 7 described above, a desired preload is applied to the balls 11, 11 by a so-called fixed position preload. That is, as described above, the pair of outer rings 10
With the end faces of the pair of outer rings 10, 10 abutting on each other, the hub 4 is internally fitted and fixed, and a pair of inner rings 8, 8 are formed with a gap 18 between the end faces of the pair of inner rings 8, 8. In the interposed state, the preload is applied to the balls 11, 11 by pressing the inner rings 8, 8 in directions approaching each other. On the other hand, an elastic material such as a coil spring or a disc spring is provided between each pair of inner rings or outer rings, and the elasticity of this elastic material is applied to each inner ring or each outer ring. There is also a method of applying a preload to each ball by a constant pressure preload. However, when the preload is applied by such a constant pressure preload, a relatively large space for installing the elastic material is required. For this reason, it is difficult to use a bearing device that applies a preload by a constant-pressure preload in the case of the information equipment or the like in which the bearing device is disposed in a very narrow space.
Therefore, when a conventional bearing device used with a preload applied is used in a relatively narrow space, the bearing device is fixed position preload as in the conventional structure shown in FIG. Is generally used.

[0007]

There are two general methods for assembling the bearing device 1 to the support shaft 3 in a state where a preload is applied by a fixed position preload. The pair of inner rings 8, 8 is externally fitted and fixed to the support shaft 3 by interference fit while applying a predetermined load to the pair of inner rings 8, 8 in a direction approaching each other. The pair of inner rings 8, 8 are externally fitted to the support shaft 3 by gap fitting, and are fixed by bonding in a state where a predetermined load is applied to the inner rings 8, 8 in a direction approaching each other.

Regardless of which of the above methods is used to apply a preload to the bearing device 1, the mounting of the bearing device 1 to the support shaft 3 is performed by a special device for applying a desired preload with high accuracy. This can only be done by manufacturers with
The reason will be described next. First, when the bearing device 1 is assembled to the support shaft 3 by the above method, a frictional force is generated at a fitting portion between the pair of inner rings 8 and 8 and the support shaft 3. Therefore, when each of these inner races 8 is fitted to the support shaft 3 by interference fit, a load obtained by adding the frictional force to a desired preload applied to each of the balls 11, 11 is applied to each of the inner races 8, 8 must be added. However, each of the inner rings 8, 8 and the support shaft 3
With regard to the diameter of, a dimensional error inevitable in manufacturing occurs. For this reason, the interference between the inner rings 8 and 8 and the support shaft 3 varies, and it is difficult to make the frictional force constant.
Therefore, even if the load (press-fit load) applied when the inner rings 8, 8 are externally fitted to the support shaft 3 can be set with high accuracy, a desired preload can be applied to each of the balls 11, 11 with high accuracy. It is difficult to give to. In particular, targeted in the bearing device of the present invention,
In the case of a small bearing device, since the preload applied to each of the balls 11, 11 is relatively small, the ratio of the frictional force to the press-fitting load increases, and it is difficult to apply the preload with high accuracy. Especially difficult.

In view of such circumstances, depending on the bearing device manufacturer, in order to apply a desired preload to each of the balls 11 and 11 with high accuracy, the natural frequency of the bearing device 1 is used instead of the press-fitting load. The amount of press-fit is regulated while observing. That is, since the natural frequency of the bearing device 1 is greatly related to the preload, if the press-fitting amount is regulated so that the natural frequency becomes an appropriate value, the inner rings 8 and 8 and the support shaft 3 are connected to each other. The preload can be applied with high accuracy regardless of the dimensional error that is inevitable in manufacturing. However, the bearing device 1
In order to appropriately regulate the natural frequency of the device, a special device for measuring the natural frequency is required.

When the preload is applied by the above method, no frictional force is generated at the fitting portion between the pair of inner rings 8 and 8 and the support shaft 3 as in the case of the above method. That is, if a predetermined load is applied to the pair of inner rings 8, 8 and the inner rings 8, 8 are fixed to the support shaft 3 by bonding, the inner rings 8, 8 and the support shaft 3 are connected to each other. A desired preload can be applied to the bearing device 1 with high accuracy regardless of the unavoidable dimensional error that occurs in manufacturing. However, in the case of the above method, a predetermined load must be continuously applied to the pair of inner rings 8, 8 until the pair of inner rings 8, 8 is bonded to the support shaft 3 with an adhesive. No. Therefore, in this case, it is necessary to maintain a state in which a predetermined load is applied to the pair of inner rings 8 and 8 until the adhesive hardens, which causes an increase in the assembly cost of the bearing device 1.
For this reason, conventionally, when the above method is adopted,
By irradiating ultraviolet rays in a state where the inner rings 8, 8 are externally fitted to the support shaft 3 while applying a predetermined load, the adhesive is instantaneously hardened by the ultraviolet rays. However, in this case, a special device for irradiating ultraviolet rays is required.

As described above, even when the preload is applied to each of the balls 11, 11 by any of the above methods,
It is necessary for a manufacturer that assembles the bearing device 1 to the support shaft to have a special device for applying a desired preload with high accuracy. For this reason, conventionally, a manufacturer of a finished product or a part (article) incorporating the bearing device 1 transports the support shaft 3 around which various components are attached to a bearing device manufacturer having the above-described special device, The bearing device manufacturer assembles the bearing device 1 to the support shaft 3. Then, the bearing device 1 assembled to the support shaft 3 is sent back from the bearing device maker to the article maker. As described above, even when a desired preload is applied to the bearing device 1 by any of the above methods, the transport work required when manufacturing an article incorporating the bearing apparatus 1 increases, and the cost of the article is reduced. It is a cause of bulking. In view of such circumstances, the present invention realizes a structure that can be easily assembled to an inner member such as a support shaft even if a manufacturer does not have a special device for applying a desired preload, and incorporates a bearing device. It was invented to reduce the cost of the product.

[0012]

According to the present invention, there is provided a bearing device comprising: a pair of outer races each having an outer raceway on each inner peripheral surface; a pair of inner races each having an inner raceway on each outer peripheral surface; A ball is provided between the raceway and each of the outer raceways so as to be freely rolled, and a cylindrical sleeve provided on the inner diameter side of the pair of inner races. A direction in which the pair of outer races abut against each other in the axial end faces facing each other, and a direction in which the pair of inner races approach each other with a gap interposed between the opposed axial end faces. By pressurizing the balls, the balls are externally fitted and fixed to the sleeve while a desired preload is applied to the balls.

[0013]

In the bearing device of the present invention having the above-described structure, even a manufacturer without a special device for applying a desired preload can easily assemble the bearing member or other inner member. For this reason, it is possible to reduce the transportation work required for manufacturing a part or a finished product incorporating the bearing device, and to reduce the cost of the component or the finished product incorporating the bearing device. Furthermore, since the same bearing device can be assembled to various devices with a highly versatile structure, the bearing device can be mass-produced and the cost of the bearing device can be reduced.

[0014]

1 to 3 show a first embodiment of the present invention. The bearing device 1a of the present invention has outer raceways 9, 9 on the respective inner peripheral surfaces thereof, and can be tightly fitted to outer members such as the hub 4 (see FIG. 7), or can be internally fitted and fixed by bonding or the like. A pair of outer rings 10a, 10a, a pair of inner rings 8, 8 having inner ring tracks 7, 7 on the respective outer peripheral surfaces, the inner ring tracks 7, 7 and the outer ring tracks 9,
9 and a plurality of balls 1 provided to be able to roll freely
1, 11 and the support shaft 3 (see FIG. 7) which is an inner member,
And a cylindrical sleeve 12 which can be externally fixed by an interference fit having a slight interference. The inner and outer peripheral surfaces of the sleeve 12 are simply cylindrical surfaces.
Also, the axial length L ₈ of each inner ring 8, 8 each outer ring 10a, less than the axial length L _10a of 10a (L ₈
< _L10a ). The axial centers of the outer raceways 9 and the inner raceways 7 are respectively aligned with the outer races 1 and 9.
0a, 10a and the inner rings 8, 8 are provided at central positions in the axial direction. That is, the center of the outer raceways 9, 9 in the axial direction and the outer races 10a, 10a in the axial direction (the outer in the axial direction means the outer races 10a, 10a and the inner races 8, 8).
Means the sides that do not face each other. Conversely, inner means each outer ring 1
0a, 10a and the sides of the inner rings 8, 8 facing each other. same as below. ) And the axial length L ₁ between the end face, the axial center and the respective outer rings 10a of the respective outer ring raceways 9, 10a
The axial length L ₂ between the axially inner end face of, and equal to each other (L ₁ = L _2). In addition, each inner ring raceway 7,
The axial length L ₃ between the 7 axial center and axially outer end face of each inner ring 8, 8, the axial direction of the axial center and the respective inner ring 8, 8 of the respective inner ring raceways 7, 7 The axial length L ₄ between the inner end face and the inner end face is equal to each other (L ₃ = L ₄ ).
Accordingly, the axial length L ₄ between the axial inner end faces of the inner rings 8, 8 and the axial centers of the inner ring tracks 7, 7 formed on the outer peripheral surfaces of the inner rings 8, 8 is equal to the inner ring 8. smaller than the axial length L ₂ between the axial center of the outer ring raceway 9 formed on the axially inner end face of the outer ring 10a provided around an inner peripheral surface of the outer ring 10a of (L ₄ <L ₂₎ . The above sleeve 1
2 of the axial length L _12, the pair of outer ring 10a, 10a
2 times the axial length L _10a (2L _10a) to be substantially equal to (L ₁₂ ≒ 2L _10a).

The balls 11, 1 are located between the inner peripheral surfaces of the outer races 10a, 10a and the outer peripheral surfaces of the inner races 8, 8, respectively.
1 and a pair of retainers 13 and
3 are provided. Each of these retainers 13, 13 is made of a synthetic resin such as polyamide 66, and is provided with a plurality of elastic pieces 15, 15 on one surface in the axial direction of the annular main parts 14, 14.
This is a crown type retainer in which pockets 16 are provided between a pair of elastic pieces 15 adjacent to each other in a circumferential direction. The main portions 14 are arranged near both ends in the axial direction of the bearing device 1a. In addition, the outer rings 10a, which are respectively located near both ends in the axial direction of the bearing device 1a,
Seal rings 17, 17 are provided between the outer peripheral surface of the outer end of the inner ring 10 and the outer peripheral surfaces of the outer ends of the inner rings 8, 8, respectively.
Both ends in the axial direction of the space where the plurality of balls 11 and 11 are installed are closed.

The inner end faces in the axial direction of the pair of outer races 10a and 10a abut against each other. Then, in this state, the pair of inner rings 8, 8 are pressed in a direction approaching each other with the gap 18 interposed between the inner end surfaces in the axial direction.
With the desired preload applied to the sleeve 12,
The outer fitting is performed by tight fitting or bonding. The inner rings 8 and 8 are externally fitted and fixed to the sleeve 12 in the conventional structure shown in FIG. 7 described above, similarly to the case where the pair of inner rings 8 and 8 are externally fitted and fixed to the support shaft 3. A bearing device manufacturer having a special device for measuring the natural frequency or a special device for irradiating ultraviolet rays performs the measurement using these special devices.

In a state where the inner rings 8, 8 are externally fitted and fixed to the sleeve 12, the outer end faces in the axial direction of the outer rings 10a, 10a are located at both axial ends of the bearing device 1a, respectively. The axial end face of the sleeve 12 is provided at substantially the same position in the axial direction. In this case, substantially the same position means that the position is not shifted in the axial direction from the dimensional tolerance required for processing.

According to the bearing device of the present invention configured as described above, even if the maker does not have a special device for applying a desired preload, the bearing device 1a of the present invention can be easily assembled to the support shaft 3. Can do things. That is, the bearing device 1 of the present invention.
In the case of a, a bearing device manufacturer having the above-mentioned special device can apply a desired preload with high accuracy by using this special device. Further, in this state, the support shaft 3 around which various components are attached is not attached to the bearing device 1a. Then, the bearing device 1a is transported by the bearing device maker to a maker of an article incorporating the bearing device, which does not have a special device for applying the preload. Then, the manufacturer of the article externally fixes the sleeve 12 constituting the bearing device 1a to the support shaft 3 by an interference fit having a slight interference. Such external fitting can be easily performed without using a special device for applying a preload. For this reason, the bearing device 1a of the present invention
Has no special device for applying the desired preload,
Even the maker of the article can easily assemble the support shaft 3. Therefore, according to the present invention, the bearing device 1
Therefore, the cost of the article incorporating the bearing device 1a can be reduced by reducing the number of transportation operations required for manufacturing the article incorporating the bearing device 1a. Further, according to the present invention, since the same bearing device 1a can be assembled to various devices, the cost of the bearing device 1a can be reduced by mass production of the bearing device 1a. When the sleeve 12 is externally fitted and fixed to the support shaft 3 by the manufacturer of the article, the sleeve 12 with respect to the support shaft 3 is so fixed that the desired preload applied to the bearing device 1a does not change. To slightly reduce the interference.

Further, in the case of this embodiment, the axial center of each of the inner ring raceways 7, 7 and the axial center of each of the outer ring raceways 9, 9 are aligned with the axial center of each of the inner races 8, 8 and the outer races 10a, 10a. It is provided at the center position in the direction. For this reason, in the case of the present example, each of the inner rings 8, 8 and each of the outer rings 10a, 10a
After the heat treatment, the inner rings 8, 8 and the outer rings 10a,
When the 10a is set in a processing device for grinding or superfinishing the inner raceways 7, 7 and the outer raceways 9, 9, etc., the inner raceways 7, 7 and the outer raceways 9, 9 are set. In consideration of the formation position of each inner ring 8, 8 or each outer ring 10a,
The troublesome work of regulating the direction of 10a can be eliminated.

In this embodiment, the sleeve 12 is externally fixed to the support shaft 3 by a tight fit with a slight interference, but the sleeve 12 is fixed to the support shaft 3 by a clearance. It can be externally fitted by fitting and fixed by bonding. When the sleeve 12 is fixed to the support shaft 3 by bonding as described above, the sleeve 12 and the support shaft 3 are placed horizontally and left with a pressing force for applying a preload applied. Preferably, the adhesive is allowed to set naturally. This is because the sleeve 12 and the support shaft 3
When the sleeve 12 is fixed to the support shaft 3 by leaving the adhesive in a state where the adhesive is naturally set in a state where the sleeve 12 is disposed in a direction inclined with respect to the vertical direction or the horizontal direction, This is because, in order to prevent the sleeve 12 from being displaced in the direction in which the sleeve 12 comes out of the support shaft 3, it is necessary to perform troublesome work of temporarily fixing the sleeve 12 to the support shaft 3 with a jig. Furthermore, when the adhesive is hardened naturally in this way, using a special device for irradiating ultraviolet rays,
There is no need to instantly harden the adhesive. In the illustrated example, the axial outer end faces of the outer races 10a and 10a and the axial end face of the sleeve 12 are substantially at the same position in the axial direction. On the other hand, the axial end face of the sleeve 12 is connected to each of the outer races 10a, 10a.
If it is located in a portion slightly depressed from the outer end face in the axial direction, it is possible to reduce the possibility that the end face of the sleeve 12 is hit during the conveyance of the bearing device 1a and the trouble that the set preload changes varies.

FIG. 4 shows a second embodiment of the present invention.
An example is shown. In the case of the bearing device 1b of the present example, the axially outer ends of the outer rings 10b and 10b and the sleeve 12a are located near both ends in the axial direction of the bearing device 1b.
Are made smaller in the axial direction at both ends in the axial direction than in the first example described above. Accordingly, in the case of the present example, the axial center of each outer ring raceway 9, 9 and the outer ring 10
b, the axial length L ₁ ′ between the outer end faces in the axial direction of 10b
To the axial center of each outer raceway 9 and each outer race 10
b, it is smaller (L ₁ '<L ₂₎ than the axial length L ₂ between the axially inner end face of 10b. That is, the axial center of each of the outer raceways 9, 9 is aligned with the outer races 10b, 10b.
They are biased to the opposite side of each other. The outer end surfaces of the outer rings 10b, 10b, the outer end surfaces of the inner rings 8, 8 and the end surface of the sleeve 12a are provided at substantially the same position in the axial direction. Note that, in this case, substantially the same position does not deviate in the axial direction than the sum of the deviation caused by applying a predetermined preload to the balls 11 and 11 and the dimensional tolerance required for processing. In the case of this example, this deviation is set to 0.25 mm or less. This shift is 0.25mm
If it is below, it can be considered that they are almost at the same position.

In the case of the present embodiment configured as described above, the overall length of the bearing device 1b in the axial direction can be made smaller than in the case of the above-described first example. Therefore, the bearing device 1b of this example
Can be incorporated in a narrower space than in the case of the first example described above. In the case of this example, the outer end surfaces of the inner rings 8, 8 and the end surface of the sleeve 12a are provided at substantially the same position in the axial direction. Therefore, this sleeve 12a
When the fitting is fixed to the support shaft 3 (FIG. 7) with an allowance, the outer diameter of the press-fitting jig is made smaller than the inner diameter of each of the inner rings 8 and 8, and each of these inner rings is press-fitted. 8, 8
The relative position in the axial direction between the shaft and the sleeve 12a is not shifted, and care is taken so that the preload set in advance does not change. Other configurations and operations are the same as those in the above-described first example, and thus redundant description will be omitted.

Next, FIGS. 5 and 6 show a third embodiment of the present invention. In the case of the bearing device 1c of this example,
The axial center of each outer raceway 9, 9 is aligned with each outer race 10c, 10
With respect to the axial direction of c, the outer rings 10c and 10c are biased to the side where they abut each other. That is, in the case of this example, the axial center of each of the outer raceways 9, 9 and the outer race 1
The axial length L ₁ ′ between the outer end faces 0c and 10c in the axial direction.
To the axial center of each outer raceway 9 and each outer race 10
c, 10c are larger than the axial length L ₂ ′ between the inner end faces in the axial direction (L ₁ ′> L ₂ ′).

In this embodiment, unlike the above-described embodiments, a seal is provided between the inner peripheral surfaces of the outer ends of the outer rings 10c, 10c and the outer ends of the inner rings 8a, 8a. The ring 17 (FIGS. 1 and 4) is not provided. Furthermore, each cage 1
The main parts 14 and 14 constituting the parts 3 and 13 are arranged near both ends in the axial direction of the bearing device 1c. In addition, each outer ring 10
c, 10c, the axial outer end surfaces of the inner rings 8a, 8a, and the axial end surfaces of the sleeve 12b.
They are provided at substantially the same position in the axial direction. In this case, substantially the same position means that there is no deviation in the axial direction more than the sum of the deviation caused by applying a predetermined preload to the balls 11 and 11 and the dimensional tolerance required for processing. However, in the case of this example, this deviation is set to 0.25 mm or less. Then, the end faces of the main parts 14, 14 constituting each of the retainers 13, 13 are the median of the dimensional permissible range of each member, and the outer rings 10 c, 10 c
In addition, the inner rings 8a, 8a do not protrude outward in the axial direction from the outer end surfaces. However, depending on the finish, the end faces of the main portions 14, 14 may be connected to the outer rings 10c, 10c.
In addition, the inner rings 8a may slightly protrude axially outward from the outer end surfaces of the inner rings 8a. Further, in the case of the present example, a part of each of the balls 11, 11 is slightly protruded in the axial direction on the side where the gap 18 exists from the axial inner end face of each of the inner rings 8a, 8a. .

In the case of the bearing device 1c of the present embodiment configured as described above, the overall length in the axial direction can be further reduced as compared with the case of the above-described second example. The reason for this is that, in the case of the present example, the axial center of each outer ring raceway 9, 9
With respect to the axial direction of 10c, each of these outer races 10c, 10c
This is because they are biased toward the side where they meet. For this reason, in the case of this example, the shoulders 19, 19 provided on the inner peripheral surface of the outer races 10c, 10c in the axial direction and the shoulders provided on the outer peripheral surface of the inner races 8a, 8a in the axial direction. Part 20
The axial lengths of a and 20a can be made smaller than the axial lengths in the above-described examples. Furthermore, in the case of the present example, each ball 11, held by each of the retainers 13, 13,
A part of 11 slightly protrudes in the axial direction from the inner end surfaces of the inner rings 8a, 8a to the side where the gap exists. Therefore, in the case of the present example, the axial length L ₅ ′ (FIG. 6) between the respective balls 11, 11 is changed to the axial direction L between the respective balls 11, 11 in the respective examples described above. It can be smaller than the length L _5.

Further, in the case of this embodiment, each of the outer rings 10
No seal ring 17 is provided between the outer peripheral surfaces of the outer ends of the inner rings 8a, 8a and the outer peripheral surfaces of the inner rings 8a, 8a. Therefore, in the case of the present example, each of the balls 1 in the bearing device 1c.
The axial length of the outer portion in the axial direction is smaller than that of the second example shown in FIG. 4 and the overall length of the bearing device 1c in the axial direction is smaller than that of the second example shown in FIG. It can be smaller than in the case. For this reason, the bearing device 1c of the present example can be incorporated in a narrower space than in the case of the above-described second example.

In the case of the present embodiment, each of the retainers 13,
The overall length of the bearing device 1c in the axial direction can also be reduced by arranging the main parts 14 and 14 constituting the portion 13 near both ends in the axial direction of the bearing device 1c. That is, each of these main parts 1
The minimum wall thickness L _{14 in} the axial direction of each of the retainers 1 and 4 is
It is necessary to increase it to some extent in order to secure the rigidity of 3 and 13. For this reason, each of the main parts 14, 14 is connected to the bearing device 1c.
Even in the case of this example, which is disposed closer to both ends in the axial direction of the bearing device 1, the minimum size of each of the main parts 14 determined by the diameter d ₁₁ of thickness L ₁₄ and the balls 11, 11, the axial end face and the balls 1 of the main portion 14, 14
The axial length between the center of _{1,11 (L 14 + d 11/} 2)
Cannot be reduced.

However, the minimum required axial lengths of the pair of shoulders 20a, 20b provided on both axial sides of the inner rings 8a, 8a are different from each other. That is, when a desired preload is applied to the balls 11, 11 by pressing the inner rings 8a, 8a in directions approaching each other, based on changes in the internal clearances of the components of the bearing device 1c, A load is applied from each ball 11, 11 to each outer ring 10c, 10c and each inner ring 8a, 8a in a direction indicated by chain lines α, α in FIG. For this reason, of the pair of shoulders 20a, 20b provided on both sides in the axial direction of the outer peripheral surfaces of the outer rings 8a, 8a, the shoulders 20b, 20b on the outer side in the axial direction are close to the point of application of the load. , Its strength is increased by the axially inner shoulder 20
a and 20a need to be greater than the strength. Therefore, the axial length of each of the axially outer shoulders 20b, 20b must be greater than the axial length of each of the axially inner shoulders 20a, 20a. Therefore, if the main parts 14 and 14 of the retainers 13 and 13 do not exist around the axially inner shoulders 20a and 20a, respectively, the axial direction of the axially inner shoulders 20a and 20a will not be present. The length can be made sufficiently small. On the other hand, each of the axially outer shoulders 20
b, the main part 1 of each of the retainers 13, 13 around
Even if there are no four and fourteen, the axial length of each of the axially outer shoulders 20b, 20b cannot be made smaller than the axially inner shoulders 20a, 20a.

In consideration of such circumstances, in the case of the present embodiment, the load is applied based on the preload application, and the load is applied around the shoulders 20b, 20b on the outer side in the axial direction of the inner rings 8a, 8a. The main parts 14, 14 of the retainers 13, 13 are arranged near both ends in the axial direction of the bearing device 1 c. For this reason, in the case of this example, each of the main parts 14
Without being hindered by the presence of the above, the above load is not applied,
The shoulders 20a, 20 on the inner side in the axial direction of the inner rings 8a, 8a.
a can be made sufficiently small in the axial direction. Therefore, the overall length of the bearing device 1c in the axial direction can be made smaller than in the above-described examples.

In the case of this embodiment, the load is applied by the balls 11, 11 based on the application of the preload.
The shoulder portions 19, 19 provided on the inner side in the axial direction of c, 10c are reduced in axial length. However, in the case of this example, since the shoulders 19, 19 have their inner end faces abutting against each other, the load applied to the shoulders 19, 19 from the balls 11, 11 is It acts in the direction in which the shoulders 19, 19 are pressed against each other, and cancel each other. Moreover, based on the existence of the gap 18 between the inner end surfaces of the inner rings 8a, 8a, the axial length of the shoulders 19, 19 on the inner side in the axial direction of the outer rings 10c, 10c is determined by the length of the inner ring. 8a, 8
a in the axial length of the shoulders 20a, 20a in the axial direction of
It is equal to the length obtained by adding half the length of the gap 18,
Will be large enough. Therefore, the strength of each of the shoulder portions 19, 19 does not become insufficient.

Further, in the case of this embodiment, the entire length of the bearing device 1c in the axial direction can be made sufficiently small, so that the hub 4 and the outer races 10c, 10c or the sleeve 12b (FIG.
) And the inner rings 8a, 8a, when the difference in linear expansion coefficient between the materials constituting the respective inner rings 8a, 8a is large, or when the outer rings 10c, 10c and the inner rings 8a, 8a have different temperatures during use. Even in the case, each member 4, 12b, 10c, 8a
The distortion based on the difference in the amount of thermal expansion in the fitting / fixing portion can be reduced. Therefore, the amount of change in bearing stiffness during use can be made extremely small. Other configurations and operations are the same as those of the first example shown in FIGS. 1 to 3 described above, and thus redundant description will be omitted.

In practicing the present invention, it is not always necessary to use an outer ring divided into two. If the manufacture and assembly are not troublesome, a pair of outer races having a double-row outer raceway on the inner peripheral surface may be used.

[0033]

Since the present invention is constructed and operates as described above, even a manufacturer without a special device for applying a desired preload can easily assemble the bearing device to the inner member. Thus, the cost of the article incorporating the bearing device can be reduced. Furthermore, mass production of bearing devices
The cost of the bearing device itself can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a perspective view showing the cage taken out.

FIG. 3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view showing a second example of the embodiment of the present invention.

FIG. 5 is a sectional view showing a third example.

FIG. 6 is an enlarged top view of FIG. 5;

FIG. 7 is a cross-sectional view showing an example of a conventional structure in a state where it is incorporated between a hub and a support shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a-1c Bearing device 2 Housing 3 Support shaft 4 Hub 5 Inner diameter side cylindrical part 6 Ball bearing 7 Inner ring raceway 8, 8a Inner ring 9 Outer ring raceway 10, 10a-10c Outer ring 11 Ball 12, 12a, 12b Sleeve 13 Cage 14 Main part 15 Elastic piece 16 Pocket 17 Seal ring 18 Gap 19 Shoulder 20a, 20b Shoulder 22 Projection 23 Projection 24 Outer diameter side cylindrical part

Claims (2)

[Claims] 1. An outer ring raceway on each inner peripheral surface.
A pair of outer races, a pair of inner races each having an inner raceway on an outer peripheral surface thereof, a plurality of balls provided so as to freely roll between the inner raceways and the outer raceways, respectively, A cylindrical sleeve provided on the inner diameter side of the inner ring;
A pair of outer races are abutted on opposing axial end faces, and the pair of inner races are pressed in a direction approaching each other with a gap interposed between the opposing axial end faces. Thus, the bearing device is fitted and fixed to the sleeve while a desired preload is applied to the balls. 2. The bearing device according to claim 1, wherein one outer ring having a double-row outer ring raceway on the inner peripheral surface is used instead of the pair of outer rings.