JP2003307213A - Bearing device and motor using the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power loss in preventing the slip-out of a rotary shaft of a bearing device, and to facilitate the manufacturing of a slip-out preventive mechanism of the rotary shaft. <P>SOLUTION: This bearing device is a bearing device having the mutually relatively rotatably arranged rotary shaft 2 and a bearing member 3. The bearing member 3 has a thrust dynamic pressure receiving surface for generating thrust dynamic pressure having at least a shaft directional pressure component of the rotary shaft when a clearance becomes smaller than a prescribed value by liquid filled in the clearance formed between the bearing member 3 and the rotary shaft 2. The power loss is reduced by dispensing with force for preventing the slip-out of the rotary shaft in an ordinary rotational state by energizing the rotary shaft in the direction for returning to an original state only when the rotary shaft tries to slip out. The manufacturing is facilitated by forming a constitution requiring no manufacturing accuracy in the constitution for preventing the slip-out of the rotary shaft. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device and a motor having the bearing device, and is applied to a cooling fan motor for a microprocessor, a hard disk, an optical disk rotating device, and various rotating devices requiring non-contact support. can do.

[0002]

2. Description of the Related Art A hydrodynamic bearing device using dynamic pressure or the like is known to have advantages of long life, quietness and high vibration resistance due to non-contact support in addition to high rotational accuracy. ing.

FIG. 3 is a schematic sectional view for explaining an example of a conventional hydrodynamic bearing device using dynamic pressure. In FIG. 3, the bearing device 101 includes a bearing member 103 including a sleeve 103 a and a housing 103 b, and a housing 103.
The rotary shaft 102 is supported in the radial direction by the sleeve 103a, and is supported in the thrust direction by the thrust plate 106 and the housing bottom part. A liquid such as oil is injected between the members of the sleeve 103a and the thrust plate 106 and into the gap formed by the rotating shaft 102. Note that FIG.
In the figure, constituent elements of the motor, such as a rotor, a rotor magnet fixed to the rotating shaft 102, a motor stator and a coil are omitted. Outer peripheral surface of rotating shaft 102 and sleeve 1
A dynamic pressure groove 131 is formed on the inner peripheral surface of 03, and a dynamic pressure is formed by the action of the dynamic pressure groove and the liquid.

When the motor stator is energized, the rotating shaft 102 starts rotating. By this rotation, the dynamic pressure groove 1
31 applies pumping pressure to the oil, and the rotating shaft 102 is supported by this pumping pressure, and the sleeve 103a
It rotates without contact with.

Conventionally, as shown in FIG. 3, the thrust shaft is supported in the thrust direction by a magnetic force of a rotor magnet, and the other end of the rotary shaft is used as a pivot. , This is done by receiving this pivot on the thrust plate. In such a bearing device, the rotation shaft is held by the magnetic attraction force of the rotor magnet in the thrust direction. However, if vibration or shock is applied to the bearing device or the posture changes, it becomes difficult to sufficiently hold the magnetic attraction force applied in the thrust direction, and there is a possibility that the rotary shaft may come off or the shaft may tilt. Therefore, in order to prevent such a disengagement of the rotary shaft, a flange is provided on the rotary shaft.

FIG. 4 is a cross-sectional view for explaining a structural example provided with a flange for preventing the rotary shaft from coming off. In FIG. 4, the magnet 112 provided on the rotor 111 and the bearing member 1
The magnetic force in the thrust direction is formed by shifting the position of the coil 113 provided on the 03 side in the axial direction of the rotary shaft 102, and the rotary shaft 102 is urged toward the bearing member 103 side by this axial attraction force to rotate. Prevents the shaft from coming off.

When a force such as vibration or shock is applied or the posture is tilted, it is difficult to prevent the rotary shaft from coming off only by the magnetic force in the thrust direction. A flange 105 is attached to one end.
When the rotating shaft 102 tries to come off due to vibration, impact, or attitude difference, the flange 105 fixed to the rotating shaft 102
Contacts a part of the bearing member 103, thereby preventing the rotating shaft from falling off. As such a configuration example, for example,
There is a motor bearing disclosed in Japanese Utility Model Publication No. 2-94922.

Further, there is known a structure in which a thrust dynamic pressure bearing is provided on the rotary shaft in order to prevent the rotary shaft from coming off.
FIG. 5 is a cross-sectional view for explaining a configuration example including a thrust dynamic pressure bearing for preventing the rotary shaft from coming off.

In FIG. 5, the flange 1 is attached to the rotary shaft 102.
No. 05 is provided and dynamic pressure grooves 105a and 105b are formed on both surfaces of the flange 105, and the flange 105 is housed in the space formed in the bearing member 103 to fill oil or the like with respect to the axial direction of the rotary shaft. Thrust dynamic pressure is generated in both directions, and the rotary shaft is held by the thrust dynamic pressure in both directions. As such a configuration example, for example,
JP-A-9-37513 and JP-A-9-32850 are known.

[0010]

In the structure for preventing the rotation shaft from slipping out in the conventionally known bearing device, in the structure using the magnetic force in the thrust direction like the former, the pivot end of the rotation shaft has the pivot receiving portion. In order not to move to the opposite side, the magnetic attraction force must be strong. In this way, when the magnetic attractive force is increased, a large pressure is applied between the pivot end of the rotary shaft and the pivot receiving portion, which increases friction at the pivot portion and causes power loss. There is a problem that balance tends to occur. Further, when the flange comes into contact with the bearing member, the brake is suddenly applied, and the flange and the bearing member generate heat due to friction, and the flange and the bearing member may be damaged.

In the latter case, in the structure in which the thrust dynamic pressure bearing is provided on the rotary shaft, the dynamic pressure generating gap formed between the flange and the bearing member sandwiching the flange from above and below is manufactured with high precision. It is necessary and difficult to manufacture. In addition, there is a problem that power loss is large because dynamic pressure is constantly generated in two directions.

Therefore, the present invention aims to solve the conventional problems and to reduce the power loss in preventing the rotation shaft of the bearing device from slipping off, and also to facilitate the manufacture of the mechanism for preventing the rotation shaft from slipping off. The purpose is to

[0013]

SUMMARY OF THE INVENTION The bearing device provided by the present invention is such that when the rotating shaft is about to come out, the rotating shaft is urged in the direction in which the rotating shaft is returned to its original position. The power loss is reduced by eliminating the need for the force to prevent slipping off. Further, in the structure for preventing the rotary shaft from coming off, the manufacturing is facilitated by adopting a structure that does not require manufacturing accuracy.

The bearing device of the present invention is a bearing device having a rotating shaft and a bearing member that are rotatably provided relative to each other, and the rotating shaft is movable in the axial direction with respect to the bearing member. For a predetermined axial movement of the rotary shaft, a dynamic pressure acting in the direction opposite to the axial direction is generated.

Further, the bearing device of the present invention is a bearing device having a rotary shaft and a bearing member that are rotatably provided relative to each other, and the bearing member fills a gap provided between the rotary shaft and the rotary shaft. A thrust dynamic pressure receiving surface that generates a thrust dynamic pressure having at least a pressure component in the axial direction of the rotary shaft when the gap becomes smaller than a predetermined value by the generated liquid is provided.

The rotary shaft has a first position where thrust dynamic pressure is generated by approaching the thrust dynamic pressure bearing surface, and a second position where thrust dynamic pressure is hardly generated by being separated from the thrust dynamic pressure receiving surface. It is possible to move in the axial direction between and. In a normal rotating state, the rotary shaft is located at the second position and separated from the thrust dynamic pressure receiving surface, so that the thrust dynamic pressure is hardly generated and the power loss is not generated. When in the second position, the axial support of the rotary shaft is performed by bringing the tip of the pivot part of the rotary shaft into contact with the bearing member without interposing the liquid. The pivot portion is supported by the bearing member via a thrust plate made of a low friction material.

On the other hand, when a force is applied in the direction in which the rotary shaft comes off due to vibration, impact, attitude difference, etc., the rotary shaft is in the first position and approaches the thrust dynamic pressure bearing surface to cause thrust motion. Pressure is generated. This thrust dynamic pressure is
It acts on the rotary shaft in a direction to prevent the rotary shaft from coming off, and returns the rotary shaft to the second position side. The bearing device of the present invention has a configuration in which the thrust dynamic pressure is generated only when a force is applied in the direction in which the rotating shaft is pulled out, and the thrust dynamic pressure is not generated in a normal rotating state. Power loss can be reduced.

In order to generate the thrust dynamic pressure, the rotary shaft has a flange, and the flange is provided so as to face the thrust dynamic pressure receiving surface with a gap filled with the liquid. Thrust dynamic pressure is generated between the flange and the thrust bearing surface. The generated thrust dynamic pressure acts in a direction to widen the gap between the flange and the thrust dynamic pressure receiving surface, and thereby prevents the rotary shaft from falling off. Thrust dynamic pressure can be generated by the thrust dynamic pressure groove,
The thrust dynamic pressure groove can be provided on at least one of the surfaces of the flange and the thrust dynamic pressure receiving surface that face each other.

The bearing member supports the rotating shaft in the thrust direction and also in the radial direction. For radial support, the bearing member is provided with a radial dynamic pressure receiving surface that faces the outer peripheral surface of the rotary shaft via a liquid-filled gap, and at least the outer peripheral surface of the rotary shaft and the radial dynamic pressure receiving surface are provided. A radial dynamic pressure groove for generating a radial dynamic pressure having at least a pressure component in a direction orthogonal to the rotation axis is provided on one side. The rotary shaft is supported in a non-contact manner by the dynamic pressure generated by the radial dynamic pressure receiving surface.

The bearing member has a housing and a sleeve fixed to the housing, and the sleeve has a thrust dynamic pressure receiving surface and a radial dynamic pressure receiving surface. The housing has a first inner peripheral surface that at least partially faces the outer peripheral surface of the sleeve, and a second inner peripheral surface that has an inner diameter smaller than the inner diameter of the first inner peripheral surface and at least partially opposes the outer periphery of the flange. And a storage hole with a surface. This storage hole is the first
The sleeve is housed in the inner peripheral surface portion of and the axial positioning is performed by the step formed at the boundary portion between the first inner peripheral surface and the second inner peripheral surface.

According to the bearing device of the present invention, when the posture of the bearing device or the motor equipped with this bearing device is changed or vibration or impact is applied, the rotary shaft can be moved in the axial direction and added. By generating a force that acts in the opposite direction to the force, it is possible to prevent the rotary shaft from coming off, and to reduce the magnetic attraction force for holding the rotary shaft in the normal state. The power loss caused by friction due to the magnetic attraction force can be reduced.

[0022]

1 and 2 are a sectional view and a partially enlarged view for explaining the outline of a bearing device of the present invention, showing a case where the bearing device is applied to a fan motor.

In FIG. 1, a bearing device 1 includes a rotary shaft 2
And a bearing member 3 that rotatably supports the rotating shaft 2. In this bearing member 3, the rotary shaft 2 is attached to the radial shaft gap 2
A sleeve 3a that supports the sleeve 3a in a non-contact manner and a housing 3b that fixes the sleeve 3a are provided. Rotating shaft 2
Fix the rotor 11 with the fan 16 to the fixing screw 15
The fan motor can be configured by fixing with
The drive mechanism of this motor can be configured by a magnet 12 attached to the rotor 11, a coil and a magnetic core 13 provided on a fixed portion such as the housing 3b side, a substrate 14 that controls a drive current to the coil, and the like. A magnetic attraction force is generated by arranging the magnet 12, the coil, and the magnetic core 13 so as to shift in the axial direction of the rotary shaft 2. This magnetic attraction force acts as a thrust load that urges the rotating shaft 2 downward.

The sleeve 3a has a cylindrical housing portion for housing the rotary shaft 2 therein. A radial dynamic pressure receiving surface 3a1 is formed on the inner peripheral portion of the sleeve 3a, and a radial shaft gap 21 is formed between the inner peripheral portion and the outer peripheral surface of the housed rotary shaft 2 so as to face each other. It is rotatably supported without contact by interposing. The housing 3b houses the sleeve 3a therein, and a housing hole 4 for positioning the sleeve 3a at a predetermined axial position.
Equipped with. The axial positioning of the sleeve 3a can be performed by bringing the lower end portion of the sleeve 3a into contact with the step portion 3b3 provided at the lower position.

Further, the housing 3b is provided with a bottom space 22 for storing the lubricating liquid at the lower position and communicating with the storage hole 4. The bottom space 22 accommodates the lower end portion of the rotating shaft 2 and the flange 5 attached to the lower end portion. A thrust plate 6 is arranged on the bottom surface of the bottom space 22 and supports the pivot portion 7 at the lower end of the rotary shaft 2 at a point.

The bottom space 22 and the radial shaft gap 21 communicate with each other, and the liquid stored in the bottom space 22 is supplied into the radial shaft gap 21 by a capillary phenomenon. The size and shape of the bottom space 22 are formed so that liquid can be supplied into the radial shaft gap 21 by a capillary phenomenon.

For example, the radial shaft gap 21 and the bottom space 2
In the communicating portion of 2, the capacity of the bottom space 22 is made sufficiently larger than the capacity of the radial shaft gap 21 so that the suction force toward the inside of the radial shaft gap 21 is increased by the capillary phenomenon. Further, the shape of the bottom space 22 is formed so that the suction force of the capillary phenomenon caused by the shape does not become larger than the suction force toward the inside of the radial shaft gap 21. For example, in the case where a shape portion that causes a capillary phenomenon, such as a comb-like shape, is formed in the bottom space 22,
The suction force of the capillary phenomenon generated by the comb-teeth shape is formed so as not to affect the supply of the liquid toward the radial shaft gap 21.

A communication hole 23 for communicating the bottom space 22 with the atmosphere is provided between the sleeve 3a of the bearing member 3 and the housing 3b, and when the liquid overflows from the gap between the sleeve 3a and the rotary shaft 2. Then, it is returned to the bottom space 22 through the communication hole 23.

In the above structure, the axial center position of the magnet 12 and the axial center position of the coil 13 are displaced from each other in the axial direction so that the rotating shaft 2 is magnetically attracted.
Is urged toward the bearing member 3 side, and the pivot portion 7 at the lower end of the rotary shaft 2 is brought into contact with the thrust plate 6 to hold the rotary shaft 2.

The bearing device of the present invention is provided with a thrust dynamic pressure holding mechanism as a mechanism for holding the rotary shaft 2 against the bearing member 3 side, in addition to the above-mentioned holding mechanism by the magnetic attraction force. This thrust dynamic pressure holding mechanism generates a thrust dynamic pressure having at least a pressure component in the axial direction of the rotary shaft only when the rotary shaft moves in the direction in which the rotary shaft comes off and the distance from the bearing member reaches a predetermined distance. , The rotary shaft is held by this thrust dynamic pressure.

The holding mechanism by the thrust dynamic pressure will be described below with reference to FIG. 2A shows the second position where the thrust dynamic pressure is generated, and FIG. 2B shows the first position where the thrust dynamic pressure is hardly generated.
In FIG. 2, the thrust dynamic pressure holding mechanism is composed of a flange 5 and a sleeve 3 a attached to the rotary shaft 2.

The sleeve 3a is positioned at a predetermined axial position with respect to the housing 3b, and the space between the lower end surface of the sleeve 3a and the bottom surface of the housing 3b forms a bottom space 22. The axial position of the sleeve 3a is determined by the second inner circumference of the housing 3b forming the side wall portion of the bottom space 22 with respect to the inner diameter of the first inner circumferential surface 3b1 of the housing 3b facing the outer circumferential surface of the sleeve 3a. Surface 3b2
By making the inner diameter of the small diameter, the step portion 3b3 is formed at the boundary portion between the first inner peripheral surface 3b1 and the second inner peripheral surface 3b2.
This can be done by bringing the lower end of the sleeve 3a into contact with the step 3b3.

In the bottom space 22, the lower end portion of the rotary shaft 2 supported by the sleeve 3a in the radial direction is movably projected in the axial direction, and this lower end portion is attracted by a magnetic attraction force in a normal rotating state. Urged downwards,
By contacting the thrust plate 6 arranged on the bottom surface in the bottom space 22, the thrust plate 6 is held by the bottom wall of the housing 6b.

A flange 5 is attached to the lower end of the rotary shaft 2. The upper surface of this flange 5 is the bottom space 2
The flange 5 and the lower end surface of the sleeve 3a opposed to the flange 5 are immersed in the bottom space 22 with the liquid filled therein. Here, the lower end surface of the sleeve 3a forms a thrust dynamic pressure receiving surface 3a2, and thrust dynamic pressure is generated between the lower end surface of the sleeve 3a and the upper end surface of the flange 5 which is arranged to face the thrust dynamic pressure. Thrust dynamic pressure receiving surfaces 3a2 facing each other
A thrust dynamic pressure groove 5a is formed on at least one of the upper end surfaces of the flange 5 and the flange 5. Although FIG. 2 shows the configuration in which the thrust dynamic pressure groove 5a is provided only on the upper end surface of the flange 5, it may be provided on the thrust dynamic pressure receiving surface 3a2 side or on both sides.

The bearing member 3 has a thrust dynamic pressure receiving surface 3a2.
When the gap between the upper surface of the flange 5 and the upper surface of the flange 5 becomes narrower and becomes smaller than a predetermined value, a thrust dynamic pressure having at least a pressure component in the axial direction of the rotary shaft 2 is generated and increased by the thrust dynamic pressure. The flange 5 is pushed downwards, which prevents the rotary shaft 2 from coming off.

Here, the predetermined value is a distance at which substantially effective thrust dynamic pressure is generated between the thrust dynamic pressure receiving surface 3a2 and the upper end surface of the flange 5, and the thrust dynamic pressure receiving surface 3a2. The area of the upper end surface of the flange 5, the shape, size, and number of the thrust dynamic pressure grooves 5a, the characteristics of the liquid, and the like are set as parameters.

With the above structure, the rotary shaft 2 approaches the thrust dynamic pressure receiving surface 3a2, and the thrust dynamic pressure is generated at the first position where the thrust dynamic pressure is generated, and the thrust dynamic pressure receiving surface 3a2.
Is separated from the second position to allow axial movement between the second position where thrust dynamic pressure is hardly generated.

FIG. 2A shows the state of the second position. In normal rotation state, magnetic attraction force (arrow A in the figure)
As a result, the rotary shaft 2 is biased downward, and the pivot portion 7 at the lower end thereof is brought into contact with the thrust plate 6. Thrust plate 6
Is made of a low friction material such as polyslide (trade name), and can be supported with low friction by supporting the pivot portion 7 of the rotary shaft 2 at a point.

At the second position, since the rotary shaft 2 is pushed to the thrust plate 6 side, the distance d2 between the thrust dynamic pressure receiving surface 3a2 and the upper end surface of the flange 5 is equal to the dynamic pressure. The intervals are so wide that they do not substantially occur, and almost no dynamic pressure is generated. Therefore, in this second position,
The rotating shaft is held by the magnetic attraction force, and no power loss occurs.

On the other hand, FIG. 2B shows the state of the first position. When vibration or shock is applied or the posture changes, a large force is applied in the direction opposite to the magnetic attraction force, and an upward force (arrow B in the figure) acts on the rotating shaft 2 to rotate it. An attempt is made to disengage the shaft 2 from the bearing device.

At the first position, the rotary shaft 2 moves upward, and the upper end surface of the flange 5 thereof comes close to the thrust dynamic pressure receiving surface 3a2 of the sleeve 3a facing the thrust dynamic pressure receiving surface. The distance d1 between 3a2 and the upper end surface of the flange 5 is narrow enough to generate dynamic pressure. At this time, since the sleeve 3a is fixed to the housing 3b, the generated dynamic pressure acts to push down the flange 5 (arrow C in the figure). When the flange 5 is pushed down by the dynamic pressure, the gap d1 between the thrust dynamic pressure receiving surface 3a2 and the upper end surface of the flange 5 moves in the expanding direction. Since the dynamic pressure also decreases as the distance d1 increases, the flange 5 is stabilized at a position where the sum of the external force and the magnetic attraction force and the dynamic pressure are balanced. When the external force such as vibration or shock disappears or the posture returns to the original position, the rotary shaft returns to the second position shown in FIG. 2A again by the magnetic attraction force.

Next, the procedure for assembling the bearing device of the present invention will be described. In the bearing device of the present invention, first, a flange is attached to the rotary shaft, and the rotary shaft with the flange attached is passed through the shaft hole of the sleeve, thereby forming an assembly unit of the rotary shaft and the sleeve. A liquid such as oil is poured into at least the bottom space in the housing hole of the housing, and the assembly unit of the rotary shaft and the sleeve is inserted into the housing until the lower end surface of the sleeve contacts the stepped portion of the housing.

By the insertion of this assembly unit, the flange and the lower end of the rotary shaft are immersed in the liquid, and the liquid in the bottom space enters and fills the radial shaft gap and the communication hole. After that, the sleeve is fixed to the housing by caulking and the rotor is attached to the end of the rotary shaft.

As described above, according to the structure of the bearing device of the present invention, the components such as the flange, the rotating shaft, and the sleeve can be assembled by a simple operation of sequentially inserting them into the accommodation hole. Further, the operation of injecting a liquid such as oil into a small diameter hole such as a radial shaft gap or a communication hole can be performed by a simple operation of immersing the liquid in the liquid.

According to the bearing device of the present invention, when a posture difference occurs or an impact is applied, the rotary shaft can move in the axial direction, and in this case, a dynamic pressure is generated in a direction to prevent slipping out. Therefore, it is not necessary to constantly generate a large magnetic attraction force, and the magnetic attraction force can be suppressed to be small.
Further, since it is not necessary to constantly generate the dynamic pressure, it is possible to reduce the power loss due to the magnetic attraction force and the friction generated by the dynamic pressure.

[0046]

According to the present invention, in preventing the rotation shaft of the bearing device from coming off, the rotation shaft can be moved in the axial direction when the posture difference occurs or a shock is applied, and the magnetic attraction force is reduced. Power loss can be reduced. Also,
It is possible to easily manufacture the mechanism for preventing the rotation shaft from coming off.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining an outline of a bearing device of the present invention.

FIG. 2 illustrates a holding mechanism of the bearing device of the present invention by thrust dynamic pressure.

FIG. 3 is a schematic cross-sectional view for explaining an example of a conventional hydrodynamic bearing device using dynamic pressure or the like.

FIG. 4 is a cross-sectional view for describing a configuration example including a conventional flange for preventing the rotary shaft from coming off.

FIG. 5 is a cross-sectional view for explaining a configuration example including a conventional thrust dynamic pressure bearing for preventing the rotary shaft from coming off.

[Explanation of symbols]

1 Bearing device 2 rotation axes 3 Bearing members 3a sleeve 3a1 Radial dynamic pressure receiving surface 3a2 Thrust dynamic pressure receiving surface 3b housing 3b1 First inner surface 3b2 second inner peripheral surface 3b3 step 4 storage holes 5 flange 5a thrust dynamic pressure groove 6 Thrust plate 7 Pivot part 11 rotor 12 magnets 13 coils 14 board 15 fixing screws 16 fans 17 Rotor fixing member 21 Radial shaft clearance 22 Bottom space 23 communication holes

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3J011 AA04 BA02 BA08 BA10 CA02                       JA02 KA02 KA03 SC20 SE10                 5H605 AA08 BB05 BB10 BB14 BB19                       CC04 DD03 DD05 DD09 EA05                       EB06 EB16 EB21 EB28                 5H607 BB01 BB07 BB09 BB14 BB17                       BB25 CC09 DD03 GG01 GG09                       GG12 GG15 GG17 GG25

Claims (13)

[Claims] 1. A bearing device having a rotating shaft and a bearing member that are rotatable relative to each other, wherein the rotating shaft is axially movable with respect to the bearing member, and A bearing device, which forms a dynamic pressure acting in a direction opposite to the axial direction with respect to a predetermined axial movement. 2. A bearing device having a rotating shaft and a bearing member that are rotatably provided relative to each other, wherein the bearing member is formed of a liquid filled in a gap provided between the rotating member and the rotating shaft. A thrust dynamic pressure receiving surface that generates a thrust dynamic pressure having at least a pressure component in the axial direction of the rotary shaft when the gap becomes smaller than a predetermined value is provided, and the rotary shaft has a thrust dynamic pressure bearing surface with respect to the thrust dynamic pressure bearing surface. Move in the axial direction between a first position where the thrust dynamic pressure is generated by approaching it and a second position where the thrust dynamic pressure is hardly generated by moving away from the thrust dynamic pressure receiving surface. A bearing device characterized by being possible. 3. The rotary shaft has a flange provided to face the thrust dynamic pressure receiving surface with a gap filled with the liquid, and the thrust dynamic pressure is the flange and the thrust bearing. The bearing device according to claim 2, wherein the bearing device is generated between the bearing device and the surface. 4. A thrust dynamic pressure groove for generating the thrust dynamic pressure is provided on at least one of the surfaces of the flange and the thrust dynamic pressure receiving surface facing each other. Bearing device according to. 5. The bearing member further has a radial dynamic pressure receiving surface which faces the outer peripheral surface of the rotating shaft via a gap filled with the liquid. The bearing device according to any one of 1. 6. A radial dynamic pressure groove for generating a radial dynamic pressure having at least a pressure component in a direction orthogonal to the rotary shaft is provided on at least one of an outer peripheral surface of the rotary shaft and the radial bearing surface. 6. The method according to claim 5, characterized in that
Bearing device according to. 7. The rotating shaft is supported in the axial direction by the bearing member without the liquid when the rotating shaft is in the second position. The bearing device according to any one of claims. 8. The bearing device according to claim 7, wherein the rotary shaft has a pivot portion, and a tip of the pivot portion is supported by the bearing member. 9. The bearing device according to claim 8, wherein the pivot portion is supported by the bearing member via a thrust plate made of a low friction material. 10. The bearing member includes a housing and a sleeve fixed to the housing, and the thrust dynamic pressure receiving surface and the radial dynamic pressure receiving surface are provided on the sleeve. The bearing device according to any one of claims 5 to 9. 11. The housing has a first inner peripheral surface, at least a part of which faces the outer peripheral surface of the sleeve, and at least one outer peripheral surface of the flange having an inner diameter smaller than the inner diameter of the first inner peripheral surface. And a storage hole having a second inner peripheral surface facing each other, the storage hole stores the sleeve in a first inner peripheral surface portion, and the first inner peripheral surface and the first inner peripheral surface. The bearing device according to claim 10, wherein the bearing device is positioned in the axial direction by a step portion formed at a boundary with the inner peripheral surface of 2. 12. The bearing device according to claim 1, wherein a fan is fixed to the rotary shaft. 13. A motor using the bearing device according to any one of claims 1 to 12.