JPH102328A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost bearing device to be low in height and formed in a compact manner, and reduce the occurrence of oscillation of a non-rotation synchronous component, and provide a means to be simple in constitution and exert a pre-load on a ball bearing instead of a high-cost rare earth magnet. SOLUTION: A ball bearing 7 having a ball 11 disposed between outer and inner ring members 9 and 8 and a radial bearing surface 12 formed on the inner peripheral surface of the inner ring member 8 is inserted externally of a radial bearing surface 5a formed on the outer peripheral surface of a shaft member 5 with a bearing gap 10 located therebetween. A groove 8a for generating a dynamic pressure is formed in the radial bearing surface 12, the outer ring member 9 and the shaft member 5 are integrally fixed, and a pressure chamber 9 is arranged between a bearing member 18 formed integrally with the inner ring member 8 and the end face 5b of the shaft member. A fluid pressure in the bearing gap 10 generated by a groove 8a for generating a dynamic pressure during the operation of a bearing device is transmitted to the pressure chamber 19 and a preload is applied to the ball bearing 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device used for video, audio, information equipment, and other precision rotating equipment such as a magnetic disk drive, an optical disk drive, a laser printer, and a VTR.

[0002]

2. Description of the Related Art As a conventional bearing device of this type, a bearing device incorporated in a spindle motor of a magnetic disk drive as shown in FIG.
No. 1702). This bearing device a is axially separated from a shaft member b fixed to a base (not shown) and a sleeve member d on which a magnetic disk (not shown) is mounted and which is rotationally driven by a rotational drive unit c. Rolling bearings (ball bearings)
e and a dynamic pressure bearing f are arranged, and a first permanent magnet g is fixed to a shaft member b near the dynamic pressure bearing f.
A second permanent magnet h, which has the same polarity and repels the first permanent magnet g, is fixed to the sleeve member d, and at least one repulsive force between the first permanent magnet g and the second permanent magnet h is fixed. By applying the force of the portion in the direction of the rolling bearing e, a preload is applied to the rolling bearing e.

[0003]

In recent years, magnetic disk drives are becoming thinner and have higher recording densities. To cope with this, the height of a spindle motor used in magnetic disk drives has to be increased. There is a demand for a low non-rotational synchronization component and a small fluctuation.

However, in the above-mentioned conventional bearing device a, the ball bearing e and the dynamic pressure bearing f are arranged above and below the shaft member b so as to be spaced apart from each other. Furthermore,
Since the permanent magnets g and h disposed above the dynamic pressure bearing f constitute a repulsion type magnetic bearing and apply a preload to the ball bearing e, it is expensive to apply a sufficient preload to the ball bearing e. It is necessary to use a magnet having a large magnetic force, such as a rare earth magnet, and there is a problem that it is difficult to reduce the cost.

Accordingly, the present invention has been made in view of such problems of the conventional bearing device, and has a small height, a compact size, a small non-rotational synchronous component swing, and a high cost. It is an object of the present invention to provide a low-cost bearing device provided with a means for applying a preload to a ball bearing having a simple configuration in place of a rare earth magnet.

[0006]

In order to achieve the above object, a bearing device according to the present invention includes a ball bearing having a ball disposed between an outer ring member and an inner ring member, and has an inner periphery of the inner ring member. The radial bearing surface provided on the surface is extrapolated through a bearing gap to the radial outer peripheral surface provided on the outer peripheral surface of the shaft member, and a groove for generating dynamic pressure is provided on at least one of the radial bearing surface and the radial outer peripheral surface, An outer ring member and a shaft member are integrally fixed, and a pressure chamber is provided between the bearing member and the end surface of the shaft member integrated with the inner ring member, and the pressure chamber is used for generating the dynamic pressure when the bearing device is operated. The fluid pressure in the bearing gap generated by the groove is transmitted to apply a preload to the ball bearing.

In the bearing device configured as described above,
Since the inner peripheral surface of the inner race member of the ball bearing is the radial bearing surface of the dynamic pressure bearing, the height of the bearing device can be reduced without the ball bearing and the dynamic pressure bearing being separated from each other above and below the shaft member. Also,
Since the fluid pressure generated by the hydrodynamic bearing is guided to the pressure chamber and used to apply preload to the ball bearing, there is no need to provide a preload applying mechanism using expensive magnets as in the past, and the cost of the entire device is reduced. Also becomes possible.

Further, since a preload acts on the ball bearing, the intersection of the contact angles of the ball bearing is located at a position distant from the maximum pressure generating portion of the dynamic pressure bearing, and the moment rigidity of the entire bearing device can be increased.

Also, one of the bearings supporting the rotating part is
Since the dynamic pressure bearing has no bearing of the non-rotational synchronous component and has a bearing gap, it is less susceptible to misalignment caused by an assembly error. Therefore, it is possible to reduce the deviation of the non-rotational synchronous component of the spindle motor.

Here, the ball bearing may be a radial ball bearing or a thrust ball bearing. Further, the ball bearing may be a radial ball bearing having an inner ring member longer in the axial direction than the outer ring member, and the pressure chamber may be formed by closing one end side of the inner ring member.

Further, the ball bearing may be a radial ball bearing in which the pressure chamber is formed by closing one end of a sleeve fixed to an inner peripheral surface of an inner race. Further, the ball bearing may be a thrust ball bearing in which the pressure chamber is formed by closing one end of the sleeve fixed to the inner diameter surface of the inner ring.

The ball bearing is a radial ball bearing, and a sleeve fixed to the inner peripheral surface of the inner ring has one end closed to form the pressure chamber and the inner ring member is fixedly supported on a base. Can be.

Further, the radial bearing surface may be provided with a tapered portion at an opening end side of a bearing gap between the radial bearing surface and the radial outer peripheral surface.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a first embodiment of the bearing device of the present invention. First, the configuration will be described.
1 shows a spindle motor 2 of a magnetic disk drive in which a bearing device 3 according to the present invention is incorporated, and a shaft member 5 fixed to a base 4 and a hub (rotating body) on which a magnetic disk (not shown) is mounted. ) 6 and a deep groove ball bearing 7 that supports the hub 6. Deep groove ball bearings 7 arranged as ball bearings
Is an inner ring 8 as an inner ring member, an outer ring 9 as an outer ring member, and a plurality of balls 1 disposed between the inner ring 8 and the outer ring 9.
1 is provided. The inner ring 8 is formed so as to protrude axially above the outer ring 9, and a cylindrical radial bearing surface 12 provided on an inner peripheral surface of the inner ring 8 is a cylindrical radial outer peripheral surface 5 a provided on an outer peripheral surface of the shaft member 5. It is extrapolated through a bearing gap 10. The outer ring 9 is fixed to the inner diameter surface of the base 4, whereby the outer ring 9 is fixed integrally with the shaft member 5 via the base 4.

The radial bearing surface 12 is provided with, for example, a spiral groove 8a for generating dynamic pressure. The radial bearing surface 12 and the radial outer peripheral surface 5a constitute a radial dynamic pressure fluid bearing R. Here, in this embodiment, the material of the inner ring 8 is bearing steel or martensitic stainless steel, and the outer layer portion serving as the inner ring raceway surface is hardened to HRC 58 or more by induction hardening or laser quenching, while the inner diameter of the inner ring 8 is The inner layer portion corresponding to the surface is softer than the outer layer portion, so that the groove 8a for generating dynamic pressure can be easily plastically formed on the radial bearing surface 12 by ball rolling. Alternatively, it is also possible to use carburized steel as the material of the inner ring 8, to perform carburizing treatment only on the outer layer portion and the end surface which will be the inner ring raceway surface, and to harden by subsequent heat treatment so that the outer layer portion and the end surface are harder than the inner layer portion. The groove 8a for generating a dynamic pressure can be plastically formed by ball rolling on the groove 12, so that the processing is facilitated, which is preferable.

The grooves 8a for generating dynamic pressure may be provided on the radial outer peripheral surface 5a of the shaft member 5. In this case, the hardness of the shaft member 5 is maintained at HRC 40 to 50 by heat treatment using martensitic stainless steel for the shaft member 5.
The groove 8a for generating dynamic pressure may be plastically worked by rolling on the radial outer peripheral surface 5a. Alternatively, the grooves 8a for generating dynamic pressure may be processed by etching.

In the present embodiment, a cylindrical roller 18 as a bearing member integrated with the inner ring 8 press-fitted into the upper part of the inner peripheral surface of the inner ring 8, and a roller closer to the radial outer peripheral surface 5 a of the shaft member 5. A pressure chamber 19 is provided between the pressure chamber 19 and the end face 5b. The fluid pressure (dynamic pressure) in the bearing gap 10 generated in the dynamic pressure generating groove 8a when the bearing device is operated, that is, when the inner ring member 8 rotates with respect to the shaft member 5 in the pressure chamber 19.
And a preload is applied to the ball bearing 7.

The hub 6 is fixed to an outer diameter surface of a portion of the inner ring 8 projecting from the outer ring 9. A rotor (magnet) 1 is provided on the inner surface of the hub 6 via a back yoke 13.
4 is fixed, and a stator 15 arranged radially opposite to the rotor 14 with an air gap therebetween is fixed to an outer diameter surface of the base 4 to form a spindle motor 2. The inner ring 8 is driven to rotate integrally with the hub 6 and thus the magnetic disk via the ball 11 as a rolling element and the fluid film of the radial dynamic pressure fluid bearing R. At the time of such driving, the grooves 8 for generating dynamic pressure are used.
Due to the pumping action a, a dynamic pressure is generated in the lubricating fluid in the bearing gap 10 so that the inner ring 8 rotates without contact with the shaft member 5. The deep groove ball bearing 7 has a radial load capacity and a thrust load capacity, and the radial dynamic pressure fluid bearing R has a radial load capacity.

On the inner peripheral surface of the lower end of the radial bearing surface 12 of the inner ring 8, there is provided a tapered portion 16 for sealing a lubricating fluid which protrudes downward from the bearing clearance 10 by surface tension. The lubricating fluid is held in the tapered portion 16 to prevent leakage to the outside of the inner ring 8 and scattering to the outside of the hub 6. The magnitude of the taper angle θ with respect to the axis of the tapered portion 16 is preferably in the range of 2 ° to 45 °. If the taper angle θ is less than 2 °, the amount of the lubricating fluid that can be held by the tapered portion 16 decreases, and the taper angle θ becomes 4 °.
If it exceeds 5 °, the lubricating fluid tends to be scattered by the centrifugal force of the rotation of the inner ring. When the rotation speed is higher than 3600 rpm, the effect of preventing the lubricating fluid from scattering becomes more remarkable when the taper angle θ is set to 30 ° or less.

If an oil repellent having the property of repelling a lubricating fluid is applied to at least one of the tapered portion 16 of the radial bearing surface 12 of the radial dynamic pressure fluid bearing R and the radial outer peripheral surface 5a, the oil repellent will The repelled lubricating fluid moves to the bearing gap 10 due to the capillary phenomenon and is not scattered to the outside, so that it is possible to reliably prevent the lubricating fluid from flowing out and scattering from the bearing gap 10. Specifically, for example, when fluorine oil is used as the lubricating fluid, the radial outer peripheral surface 5a
When mineral oil or synthetic oil is used as the lubricating fluid, at least one of the radial outer peripheral surface 5a and at least one of the tapered portions 16 is coated with a fluorine-based oil. It is advisable to deposit a membrane.
Further, an oil repellent may be applied to the entire surface of the radial bearing surface 12.

Next, the operation will be described. The main effects of this embodiment are summarized as follows. Since the inner diameter surface of the ball bearing 7 is configured as the radial bearing surface 12 of the hydrodynamic bearing, the bearing device 3 and thus the spindle motor 2
The effect that the whole height dimension can be reduced is obtained.
Further, by configuring one of the two sets of bearings of the bearing device 3 as a radial hydrodynamic fluid bearing R having a bearing clearance 10, the two sets of bearings are compared with a case where ball bearings are used. It is possible to prevent the non-rotational synchronous component from increasing due to misalignment, and to reduce the non-rotational synchronous component of the spindle motor 2. Further, since the preload is applied to the ball bearing 7 by utilizing the pressure generated in the hydrodynamic bearing R, it is not necessary to separately provide a preload applying mechanism using a permanent magnet or the like outside the bearing device. The effect that cost can be obtained is obtained.

That is, when the inner ring 8 rotates together with the hub 6 by the rotational drive of the spindle motor 2 to operate the bearing device, the pressure of the lubricating fluid previously supplied into the bearing gap 10 increases, and the radial bearing surface 12 Bearing clearance 10
And is supported by the radial outer peripheral surface 5a in a non-contact manner. In this case, it is not necessary to dispose two ball bearings in the axial direction, and a compact bearing device having a low axial height is provided.
The height of the spindle motor 2 incorporating this is inevitably reduced. At the same time, the pressure of the lubricating fluid generated by the operation of the radial dynamic pressure fluid bearing R is also transmitted to the pressure chamber 19 of the closed space, and the inner ring 8 of the bearing device 3 is moved upward (the opposite side of the ball bearing 7) in the figure. Press. Thereby, the deep groove ball bearing 7
Ball 11 is given an upward preload, and the ball bearing 7 is
To support the radial load and the thrust load applied via the. At this time, the point A which is the intersection of the contact angles in the ball bearing 7 becomes as shown by a dashed line in FIG. 1 and is located on the opposite side of the fluid dynamic bearing from the point B which is the maximum pressure generating portion of the radial dynamic pressure fluid bearing R. Since it is located at a lower distant place, there is also an effect that the moment rigidity of the entire bearing device 3 can be increased.

Thus, according to the present embodiment, the required rigidity can be given to the ball bearing 7 without providing a separate ball bearing preload applying means, for example, by using an expensive rare earth magnet. Cost reduction of the whole apparatus can be realized. In addition, since the radial hydrodynamic bearing R is formed by using the inner diameter surface of the inner ring 8 of one deep groove ball bearing 7 as the radial bearing surface 12, a combination of two ball bearings as in a conventional bearing device is used. Thus, it is possible to prevent the non-rotational synchronous component from increasing due to misalignment, and as a result, it is possible to reduce the non-rotational synchronous component of the spindle motor 2.

Further, in this embodiment, since the inner ring 8 of the deep groove ball bearing 7 is damped by the fluid film of the radial hydrodynamic bearing R, an indentation is less likely to be formed on the ball and the raceway by an external impact. In particular, a portable magnetic disk device can have excellent shock resistance, and the hub 6 is also supported by a damper with a fluid film, so that vibration during rotation can be suppressed well.

FIG. 2 shows a bearing device according to a second embodiment of the present invention. In addition, parts that are the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

The bearing device 21 of this embodiment uses a normal type deep groove ball bearing 22. Then, a sleeve 24 longer than the ball bearing width is fixed to the inner diameter surface of the inner ring 23 of the ball bearing 22, and the upper part of the sleeve projects above the upper end of the inner ring 23. In this case, the inner ring 23 and the sleeve 24 constitute the inner ring member of the present invention. The sleeve 24 is made of a soft metal such as free-cutting brass or phosphor bronze having good workability and slidability. The sleeve 24 has a radial bearing surface 12 which is an inner peripheral surface thereof. A generating groove 8a is provided. Also, sleeve 2
The projecting upper end of the sleeve 4 is integrally rotatably assembled to the hub 6. The upper end of the sleeve 24 is closed between the upper end of the sleeve 24 and the hub 6 with a lid member 25 serving as a disk-shaped shaft member interposed therebetween. As a result, the bearing member 2 integrated with the inner ring member is formed.
A pressure chamber 19 is formed between the shaft member 5 and the end face 5b of the shaft member 5 in an axial gap.

This embodiment includes a normal deep groove ball bearing 2
2 is used, so that the inner ring member 8 is specially lengthened.
There is an advantage that it can be made easier and cheaper than in the case of the above first embodiment using. Further, since a soft metal such as free-cutting brass or phosphor bronze is used as the material of the sleeve 24, the working of the groove 8a for generating dynamic pressure on the inner surface thereof can be easily performed by plastic working by ball rolling, and the start-up is performed. There is an advantage that wear caused by contact between the shaft member 5 and the radial bearing surface 12 at the time is reduced.

When the material of the sleeve 24 is a synthetic resin such as polyphenyl sulfide having good slidability, which can be injection-molded, the groove 8a for generating dynamic pressure can be formed on the inner peripheral surface of the sleeve 24 during the injection molding. In addition, since the sleeve 24 and the lid member 25 can be formed as one integral part with the groove 8a for generating dynamic pressure, the cost can be further reduced.

Further, since the pressure chamber 19 is formed with the lid member 25 interposed therebetween, there is an advantage that processing can be performed easily and at a lower cost than in the first embodiment formed by fitting the cylindrical roller 18.

The other structures, functions and effects are the same as those of the first embodiment. FIG. 3 shows a third embodiment of the bearing device of the present invention. In addition, parts that are the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

The bearing device 31 of this embodiment has an increased axial load capability by using a thrust ball bearing 32 as a ball bearing. A sleeve 34 as a rotating body is provided on the inner diameter surface of the inner ring 33 of the thrust ball bearing 32.
And the inner ring 33 and the sleeve 34 constitute an inner ring member of the present invention. On the other hand, the outer ring 35 constituting the outer ring member of the present invention is fitted and fixed to the base 4. The inner peripheral surface of the sleeve 34 is a radial bearing surface 12,
There is a groove 8a for generating dynamic pressure of the radial dynamic pressure fluid bearing R.
(In this case, having an asymmetric herringbone groove pattern). A pressure chamber 19 is formed between the ball 36 and the end surface 5b of the shaft member 5 by press-fitting a ball 36 as a bearing member into the upper portion of the inner peripheral surface of the sleeve 34 to form an integral body. ing.

A hub 3 is provided on the outer diameter surface of the upper portion of the sleeve 34.
A rotor (magnet) 38 is fixed to an outer peripheral portion of the hub 37, and a stator 39 is axially opposed to the outer peripheral portion of the base 4 with an air gap therebetween. Are fixed to form a spindle motor 40 of a flat facing type, and the drive of the motor 40 rotates the hub 37 and thus the magnetic disk.

According to the bearing device 31 of this embodiment, since the thrust ball bearing 32 is used as the ball bearing, there is an advantage that a bearing having high axial load capability can be obtained. Also,
Since the grooves 8a for generating dynamic pressure of the radial dynamic pressure fluid bearing R are formed in an asymmetric herringbone groove pattern, there is an advantage that the radial rigidity of the radial dynamic pressure fluid bearing R is higher than that of the first embodiment. . Further, since the pressure chamber 19 is formed only by press-fitting the inexpensive ball 36 into the sleeve 34, the first embodiment in which the cylindrical roller 18 is fitted or the second embodiment using the plate-shaped lid member 25 is used. There is an advantage that it can be made easier and cheaper than the embodiment. Further, since the spindle motor 40 is of the planar facing type, there is an advantage that the magnetic attraction in the axial direction can be increased and the hub 37 can be easily prevented from falling off the shaft member 5 during transportation.

The other structures, functions and effects are the same as those of the first embodiment. FIG. 4 shows a fourth embodiment of the bearing device of the present invention. In addition, parts that are the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

The bearing device 41 of this embodiment is provided with the first
The difference is that the bearing device of each of the third to third embodiments is of a shaft rotation type, while being of a fixed shaft type.
That is, in the bearing device 41, the sleeve 42 is fixed to the base 4, and the inner ring 23 of the normal type deep groove ball bearing 22 is integrally fixed to the outer diameter surface of the sleeve 42,
And the sleeve 42 constitute an inner race member. On the radial bearing surface 12 of the inner diameter surface of the sleeve 42, for example, a groove 8a for generating a dynamic pressure having an asymmetric herringbone groove pattern is formed. On the other hand, the outer ring 9 constituting the outer ring member of the present invention is fixed to a hub 43 which is a rotating member, and a plurality of balls 11 are provided between the inner ring 23 and the outer ring 9.
Are arranged. Specifically, the hub 43 has an upper end fixed to the shaft member 5 and extends downward, and the shaft member 5 constituting a rotating member is fixed to the outer ring 9 via the hub 43. The radial outer peripheral surface 5 a of the outer diameter surface of the shaft member 5 is disposed on the radial bearing surface 12 of the inner diameter surface of the sleeve 42 with a bearing gap 1.
0. An annular concave portion 44 is provided on the lower surface of the hub 43 between the innermost peripheral surface 43n of the hub and the outermost peripheral surface 43g of the hub, and the outer ring 9 of the deep groove ball bearing 22 is provided on the innermost peripheral surface 43n of the hub. It is fixed. The rotor (magnet) 14 is fixed to the inner peripheral surface 44n of the annular concave portion 44 via the back yoke 13, and
The outer surface 45g of the annular protrusion 45 of the base 4 protruding into the annular recess 44 is provided with the rotor 1
4 stator 1 arranged circumferentially opposite via an air gap
5 is fixed to form a spindle motor 50.

The pressure chamber 14 in this embodiment is
The flat plate 46 as a bearing member fixed to the sleeve 42 by, for example, caulking the opening at the lower end of the sleeve 42 and the shaft member 5
In the axial direction between the end face 5b and the end face 5b.

The operation and effect of the spindle motor 50 having the shaft member rotating type bearing device 41 configured as described above are the same as those of the spindle motor 2 of the first embodiment having the shaft member fixed type bearing device 3. Since it is not essentially different from the above, the description is omitted.

In each of the above embodiments, the spiral groove pattern and the symmetric or asymmetric herringbone pattern are exemplified as the groove patterns of the grooves 8a for generating dynamic pressure.
The groove pattern is not particularly limited, and another groove pattern may be employed.

Further, in each of the above embodiments, the groove 8a for generating dynamic pressure is provided only on the radial bearing surface 12, but it is not always necessary to do so. May be provided on the radial outer peripheral surface 5 a of the shaft member 5, or may be provided on both the radial bearing surface 12 and the radial outer peripheral surface 5 a of the shaft member 5. If grooves 8a for generating dynamic pressure are provided only on the radial outer peripheral surface 5a,
The inner ring 8 has the advantage that it can be made of the same material and heat treatment as a normal ball bearing.

In the above embodiment, a deep groove ball bearing or a thrust ball bearing is employed as the ball bearing.
The present invention is not limited to this. For example, other ball bearings such as a four-point contact ball bearing can be appropriately selected and adopted, and the type, structure, material, heat treatment, and the like of the ball bearing are also limited to the above embodiment. It is not necessary to carry out, and it may be changed appropriately.

Further, the shaft member 5 and the base 4 may be formed as one member to form a shaft member, and the shaft member may be directly fixed to the outer ring member or the inner ring member. Alternatively, the shaft member 5 and the hub 43 may be formed as a single member to form a shaft member, and the shaft member may be directly fixed to the outer race member 9.

[0042]

As described above, in the bearing device of the present invention, since the fluid pressure of the hydrodynamic bearing is used to apply the preload to the ball bearing, it is not necessary to use an expensive rare earth magnet as in the prior art. Since the two sets of bearings are not largely separated in the axial direction, there is an effect that a compact bearing device having a low axial height can be provided at low cost. Moreover,
Since one of the two bearings is not a ball bearing but a hydrodynamic fluid bearing, it is possible to prevent an increase in run-out of non-rotational synchronous components due to misalignment caused by the combination of conventional ball bearings.
As a result, it is possible to obtain an effect that the vibration of the non-rotational synchronous component of the spindle motor or the like can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a bearing device according to the present invention.

FIG. 2 is a sectional view of a bearing device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the bearing device of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the bearing device of the present invention.

FIG. 5 is a cross-sectional view of a spindle motor incorporating a conventional bearing device.

[Explanation of symbols]

 Reference Signs List 3 bearing device 5 shaft member 5a radial outer peripheral surface 5b end surface 7 deep groove ball bearing (ball bearing) 8 inner ring (inner ring member) 8a groove for generating dynamic pressure 9 outer ring (outer ring member) 10 bearing clearance 11 ball 12 radial bearing surface 16 Tapered portion 19 Pressure chamber 21 Bearing device 22 Deep groove ball bearing (Ball bearing) 23 Inner ring (Inner ring member) 24 Sleeve (Inner ring member) 31 Bearing device 32 Thrust ball bearing 33 Inner ring (Inner ring member) 34 Sleeve (Inner ring member) 35 Outer ring (Outer ring member) 18 Roller (bearing member) 25 Lid member (bearing member) 36 Ball (bearing member) 46 Flat plate (bearing member)

Claims (1)

[Claims] A ball bearing having a ball disposed between an outer ring member and an inner ring member, wherein a radial bearing surface provided on an inner peripheral surface of the inner ring member is provided on a radial outer peripheral surface provided on an outer peripheral surface of the shaft member. A groove for generating dynamic pressure is provided on at least one of the radial bearing surface and the radial outer peripheral surface while being externally inserted through a bearing gap, an outer ring member and a shaft member are integrally fixed, and a bearing integrated with the inner ring member is provided. A pressure chamber is provided between the member and the end face of the shaft member, and the fluid pressure in the bearing gap generated by the groove for generating dynamic pressure is transmitted to the pressure chamber during operation of the bearing device, and a preload is applied to the ball bearing. A bearing device characterized by being provided.