JP2000352417A - Air dynamic pressure bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain abrasion powders generated from a dynamic pressure bearing part from leaking from an air dynamic pressure bearing device with simple structure. SOLUTION: In this bearing device, an annular magnet 13 for attracting abrasion powders generated from a dynamic pressure bearing part is disposed to one surface of a communicating passage B for exhausting air from the dynamic pressure bearing part. Most powders generated from a dynamic pressure bearing surface are held by a magnetic force of the annular magnet 13 without leaking from the communicating passage B. These abrasion powders are attracted by a magnetic field due to a polarised surface, whereby these abrasion powders are prevented from leaking from the bearing device through a gap C which communicates with an outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of using a magnet material on one surface of a communication passage from an air dynamic pressure bearing to the outside air so that wear powder generated from the bearing portion is adsorbed on the magnet material. To a dynamic air bearing device.

[0002]

2. Description of the Related Art In recent years, polygon mirrors, magnetic disks,
Various proposals have been made for hydrodynamic bearing devices with respect to motors and the like for rotationally driving various rotating bodies such as optical disks. In this hydrodynamic bearing device, the hydrodynamic bearing surface on the shaft member side and the hydrodynamic bearing surface on the bearing member side are provided to face each other with a predetermined minute gap therebetween. A part is formed.

[0003] A dynamic pressure generating groove is formed on one of the opposing dynamic pressure bearing surfaces as described above, and the dynamic pressure generating groove formed with the dynamic pressure generating groove is formed. A lubricating fluid such as air or oil is injected into the bearing.
When the shaft member and the bearing member rotate relative to each other, the lubricating fluid is pressurized by the pumping action of the groove for generating dynamic pressure to generate a dynamic pressure in the lubricating fluid. The members and the two members float relatively to each other, so that the two members are supported so as to be relatively rotatable.

[0004]

However, in such a dynamic pressure bearing device, there is a time zone in which the dynamic pressure is not sufficiently generated at the time of starting or stopping rotation, and at that time, the shaft member and the bearing are not provided. The two hydrodynamic bearing surfaces of the members come into contact with each other. Therefore, the dynamic pressure bearing surface
The bearing is gradually worn, and wear powder is generated from the dynamic pressure bearing surface. In particular, in an air dynamic pressure bearing device using air as a lubricating fluid, the abrasion powder leaks as it flows in the communication passage from the open end side of the dynamic pressure bearing portion to the outside along with the airflow. , Floating around the dynamic pressure bearing portion.

Although the appropriateness of sealing such abrasion powder generated from the dynamic pressure bearing portion is currently being studied, especially when an air dynamic pressure bearing is used in a hard disk drive or the like, the dynamic pressure bearing portion is not suitable. In many cases, the abrasion powder leaking and floating adheres to the disk surface and causes a disk error. Under such circumstances, a drive device using an air dynamic pressure bearing is not usually used for a rotating device requiring cleanliness such as a hard disk.

The present invention suppresses the leakage of abrasion powder generated from the sliding surface of the bearing portion to the outside of the air dynamic pressure bearing portion with a simple configuration, so that the dust caused by the abrasion powder, which is a disadvantage of the air dynamic pressure bearing, is reduced. It is an object of the present invention to provide an air dynamic pressure bearing which eliminates the adverse effects of the above and can be used for a precision rotating device which does not like the influence of wear powder.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a dynamic pressure surface of a shaft member and a dynamic pressure surface of a bearing member rotatably mounted on the shaft member are provided. A dynamic pressure bearing portion is formed facing the pressure surface, and the two members are rotated and supported by a dynamic pressure effect of air interposed in the dynamic pressure bearing portion formed by the pair of opposed dynamic pressure surfaces. An air dynamic bearing in which a pair of opposed wall surfaces extending from each of the pair of opposed dynamic pressure surfaces toward the outside of the bearing defines a communication passage connecting the open end of the dynamic pressure bearing portion to the outside of the bearing. In the device, one wall surface of a pair of opposed wall surfaces constituting the communication path is formed of a magnet material that adsorbs abrasion powder generated from the dynamic pressure bearing portion,
One wall surface and the other wall surface made of the magnet material are opposed to each other with an interval capable of adsorbing the wear powder.

According to the second aspect of the present invention, at least one of the shaft members according to the first aspect is made of a magnetic material.

According to a third aspect of the present invention, the magnetic material according to the second aspect is made of a magnet material or a ferromagnetic material.

According to a fourth aspect of the present invention, the magnet material according to the third aspect is made of a soft ferrite or a sintered ferrite magnet.

According to a fifth aspect of the present invention, one of the shaft member and the bearing member according to the first aspect is made of a ferromagnetic material, and the other has a higher hardness than the ferromagnetic material. Of non-magnetic materials.

In the invention according to claim 6, both the shaft member and the bearing member according to claim 1 are both made of a magnetic material.

According to a seventh aspect of the present invention, the magnet material or the ferromagnetic material according to the third aspect is used so as to form at least a dynamic pressure bearing surface.

According to an eighth aspect of the present invention, the magnetic material according to the first aspect is multipolar magnetized in the circumferential direction.

According to a ninth aspect of the present invention, the communication path according to the eighth aspect extends radially outward from the dynamic pressure bearing portion and then concentrically surrounds the shaft member and the bearing member. It is arranged bent.

According to a tenth aspect of the present invention, the magnet material or the ferromagnetic material according to the third aspect is formed of a ceramic body.

According to the first aspect of the present invention having such a configuration, the wear powder generated from the dynamic pressure bearing portion is disposed on one surface of the communication passage extending from the dynamic pressure bearing portion to the outside of the machine. It is adapted to be adsorbed by the material.

Further, according to the second or third or sixth or seventh aspect of the present invention, the abrasion powder generated on the shaft member and the bearing member is more reliably attracted to the magnet surface of the communication passage.

Further, according to the invention as set forth in claim 4 or 10, even if the mating member is a metal body, no seizure due to heat generation due to rotational contact does not occur.

Further, according to the invention described in claim 5,
Since a non-magnetic material with high hardness is used, the amount of wear powder leaking from the dynamic pressure bearing surface is suppressed.

Further, according to the present invention, the abrasion powder generated from the dynamic pressure bearing surface is more reliably adsorbed on the surface of the magnet material in the communication path in the circumferential direction. I have.

Further, according to the ninth aspect of the present invention, most of the wear powder is reliably attracted to and held by the magnet surface of the communication path in the bent communication path before leaking out of the machine.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the air dynamic pressure bearing according to the present invention is applied to a fixed shaft type hard disk drive motor will be described below in detail with reference to the drawings.

The air dynamic pressure bearing shown in FIG.
A stator set 1 as a fixing member attached to the side,
A rotor set 2 as a rotating member is fitted to the stator set 1 so as to be fitted from above in the figure. A fixed shaft 11 is fitted to the frame 10 so as to stand upright at a substantially central portion thereof, and has a cylindrical shape that concentrically surrounds the outer peripheral portion of the fixed shaft 11 at a predetermined distance from the outside in the radial direction. Core holder 12
Are provided integrally with the frame 10.

In an annular gap formed between the core holder 12 and the fixed shaft 11, a bearing sleeve as a bearing member constituting the rotor set 2 rotatably mounted on the fixed shaft 11. 21 are arranged so as to be inserted in the axial direction. Although the configuration of the rotor set 2 will be described later, an annular magnet 13 is attached to the inner peripheral cylindrical surface of the cylindrical core holder 12 constituting the stator set 1 over the entire circumference. The inner wall surface 13 is disposed so as to face the outer wall surface 21b of the bearing sleeve 21 at a predetermined interval in the radial direction.

Further, an iron core 14 is fixed to the outer peripheral cylindrical surface of the cylindrical core holder 12, and each salient pole arranged at a predetermined interval in the circumferential direction in the iron core 14. , The drive winding 15 is wound.

The outer peripheral cylindrical surface 11a of the fixed shaft 11 has
A radial dynamic pressure surface is formed, and a plurality of radial dynamic pressure generating grooves 11c having a shape inclined toward the center in the axial direction (vertical direction in the drawing) are formed from both shaft end edges of the fixed shaft 11. The upper and lower blocks are recessed so as to be annularly arranged in parallel. The dynamic pressure generating groove 11c extends from both ends of the shaft so as to incline at a constant angle with respect to the axial direction, and the obliquely extending front end is closed. The closed portion at the tip becomes a maximum pressurized portion by a radial pumping action on supply air as a dynamic pressure fluid described later.

On the other hand, the rotor set 2 includes a rotating hub 22 for holding a hard disk (not shown). A bearing sleeve 21 that constitutes a bearing member for the fixed shaft 11 is formed integrally with an inner peripheral portion of the main cylindrical portion 22a of the rotary hub 22, and the main cylindrical portion 22a of the rotary hub 22 is illustrated in FIG. An annular drive magnet 25 is fixed via a yoke plate 24 to the inner peripheral wall surface of the enlarged attachment portion 22b provided on the lower portion.

A radial dynamic pressure surface is formed on the inner peripheral wall surface 21a of the bearing sleeve 21, and the radial dynamic pressure surface is radially close to the radial dynamic pressure surface of the fixed shaft 11 formed as described above. They are arranged to face each other. The gap between the pair of opposed radial dynamic pressure surfaces forms a radial dynamic pressure bearing portion.

Further, at the upper end of the fixed shaft 11 in the figure,
A cylindrical recess 16 for inserting a thrust shaft 23 forming a thrust bearing portion is provided, and a disc-shaped thrust plate 17 is attached to the bottom surface of the recess 16. A substantially cylindrical sealing magnet 18 is provided on the inner peripheral surface on the upper side in the drawing, which is the open side of the cylindrical concave portion 16.

The central portion of the rotary hub 22 is disposed facing the upper end of the fixed shaft 11 in the figure with a predetermined gap therebetween in the axial direction. Thrust shaft 23 erected to protrude
Is accommodated in a cylindrical recess 16 provided at the upper end of the fixed shaft 11 in the figure. The thrust dynamic pressure surface provided on the lower end surface of the thrust shaft 23 in the figure is disposed so as to be axially close to the thrust dynamic pressure surface provided on the thrust plate 17 on the fixed shaft 11 side. An axial gap between the pair of opposed thrust dynamic pressure surfaces forms a thrust dynamic pressure bearing portion. On at least one side of the pair of opposing thrust dynamic pressure surfaces, a thrust dynamic pressure generating groove (not shown) having a predetermined shape is recessed so as to be annularly arranged in parallel.

When the rotor set 2 rotates, the dynamic pressure generated in the radial dynamic pressure bearing portion and the thrust dynamic pressure bearing portion in each direction causes the rotor set 2 to rotate.
Are held in a floating state in each direction. A yoke plate 24 is provided on the inner peripheral wall surface of the enlarged mounting portion 22b provided on the lower portion of the rotary hub 22 in the figure.
The ring-shaped drive magnet 25 is fixed via the.

Here, air as the dynamic pressure fluid from both bearing ends of the fixed shaft 11 is supplied from the above-mentioned thrust dynamic pressure generating groove to the radial dynamic pressure generating groove 11c, and is supplied to the radial dynamic pressure generating groove 11c. The air that has been pressurized by the groove 11c moves through the gap A between the fixed shaft 11 and the bearing sleeve 21, and the air that has moved downward in the drawing passes through an air passage configured as follows. It is discharged outside the motor.

That is, when the rotor set 2 is mounted on the stator set 1 configured as described above so as to be fitted therein, the thrust shaft 23 is attached to the upper end recess 16 of the fixed shaft 11.
The bearing sleeve 21 is inserted into a portion between the core holder 12 and the fixed shaft 11 concentrically arranged on the frame 10 while being fitted inside the thrust plate 17. Further, the driving magnet 25 is arranged so as to be close to the outer peripheral surface of the iron core 14.

As a result, the fixed shaft 11, the bearing sleeve 21, the annular magnet 13, the core holder 12, the drive winding 15, the iron core 14, and the motor driving magnet 25 are arranged from the center of the motor toward the outside in the radial direction. Are arranged in order with a predetermined interval (gap). As shown in FIG. 1, the communication paths A, B, and C formed by the gaps between the respective members are connected to the above-described radial bearing portion. Is formed into a shape that is continuously bent so that the lower end side of the motor and the outside of the motor communicate with each other. As described above, the air discharged from the gap A on the open end side between the fixed shaft 11 and the bearing sleeve 21 is supplied to the communication passage B, which is the gap between the bearing sleeve 21 and the annular magnet 13, and the iron core. It is discharged to the outside of the motor through a communication path C which is a gap between the motor 14 and the driving magnet 25.

During normal operation of such an air dynamic pressure bearing device, the rotor set 2 floats relative to the stator set 1 due to the dynamic pressure action of air interposed in the radial bearing portion as described above. It is rotatably supported with a predetermined gap. However, when the rotation of the rotor set 2 is stopped and when the rotation is stopped, the dynamic pressure is not generated or not sufficiently generated, so that the respective dynamic pressure surfaces of the stator set 1 and the rotor set 2 come into contact with each other. A small amount of abrasion powder is generated by the contact. Therefore, in the present embodiment, external leakage of the wear powder is prevented by the following configuration.

First, the distance between the inner peripheral side wall surface 13a of the annular magnet 13 and the outer peripheral side wall surface 21b of the bearing sleeve 21, which is a pair of wall surfaces constituting the communication passage B, is determined by the air dynamic pressure bearing. Appropriate intervals are set so that the abrasion powder generated and flowing from the portion can be favorably adsorbed by the annular magnet 13. Further, the inner peripheral surface 13a of the annular magnet 13 is subjected to multipolar magnetization as shown in FIG.

Further, the fixed shaft 11 as the shaft member and the bearing sleeve 21 as the bearing member are configured as described below, and all the wear powder generated in the air dynamic pressure bearing portion is made of a ferromagnetic material. As a result, the wear powder
When moving to the outside of the motor through the motor, almost all of it is attracted to the annular magnet 13 so that the leakage of the wear powder to the outside can be prevented well.

(1) Structure of Fixed Shaft 11: Soft oxide magnetic material containing Fe ₂ O ₃ as a main component, that is, soft ferrite, or sintered ferrite magnet having a composition of BaFe ₁₂ O ₁₉ or SrBaFe ₁₂ O ₁₉ , Using either.

(2) Structure of the bearing sleeve 21: The rotating hub 22 made of a nonmagnetic material such as ferrite stainless steel or an aluminum alloy which is a ferromagnetic material integrally formed with the rotating hub 22.
Is coated with a ferromagnetic material such as Ni-Co, Ni-Fe, or a ferromagnetic material such as Ni-Co, Ni-Fe as a corrosion-resistant coating on a hub made of free-cutting steel. The one using any of
When such a configuration is employed, all the wear powder generated from the shaft member and the bearing member becomes a ferromagnetic material, and a good magnetic attraction action can be obtained. In the case of the above (1), it is desirable to perform magnetization in relation to the magnetic permeability.

On the other hand, in the embodiment according to FIG. 3 in which members corresponding to the embodiment according to FIG. 1 are represented by the same reference numerals, a bearing sleeve 31 as a bearing member is formed by a member separate from the rotating hub 22 and is rotated It is joined to the inner peripheral surface of the hub 22. The radial dynamic pressure surface formed on the inner peripheral wall surface 31 a of the bearing sleeve 31 is disposed so as to be radially close to and opposed to the radial dynamic pressure surface of the fixed shaft 11.
A radial dynamic pressure bearing portion is formed by a gap between the pair of opposed radial dynamic pressure surfaces.

Further, the air that has moved in the gap A between the fixed shaft 11 and the bearing sleeve 31 and has moved downward in the drawing, has an outer peripheral side wall surface 31 b of the bearing sleeve 31 and an inner peripheral side wall surface 13 a of the annular magnet 13. Is discharged to the outside of the motor through the communication passage B, which is a gap between the annular magnets 13. Appropriate intervals are set so as to enable good suction.

At this time, the fixed shaft 11 and the bearing sleeve 31 are configured as follows. (3) Configuration of fixed shaft 11; soft oxide magnetic material containing Fe ₂ O ₃ as a main component, that is, soft ferrite, or sintered ferrite magnet having a composition of BaFe ₁₂ O ₁₉ or SrBaFe ₁₂ O ₁₉ , or High hardness ceramics such as Al ₂ O ₃ and Si ₃ N ₄ , or ferromagnetic materials and non-magnetic materials, regardless of the surface
One having a high hardness coating such as an L (diamond-like) coating.

(4) Structure of the bearing sleeve 31: A soft oxide magnetic material containing Fe ₂ O ₃ as a main component, that is, soft ferrite, or a sintered ferrite magnet having a composition of BaFe ₁₂ O ₁₉ or SrBaFe ₁₂ O ₁₉ Or ferromagnetic stainless steel or quench hardening stainless steel, or free-cutting steel or hardened tool steel, which is a ferromagnetic material. Plated or non-magnetic material such as aluminum alloy, Ni-C
o, those plated with a ferromagnetic material such as Ni-Fe.

In the case of the above (3), the whole of each member is made of a ferromagnetic material.
In the case of (1), the abrasion resistance is good and almost no wear occurs. Further, in the case of (4),,,, the whole of each member is made of a ferromagnetic material, and in the case of (4), only the surface layer is made of a ferromagnetic material. Even in such a configuration, all the wear powder generated from the shaft member and the bearing member becomes a ferromagnetic material, and a good magnetic attraction action can be obtained.

As shown in FIG. 1 or FIG. 3, if the wall on one side of the communication passage B from the dynamic pressure bearing portion to the outside of the motor is formed of an annular magnet 13, the fixed shaft 1 as a shaft member can be formed.
Most of the abrasion powder generated by the contact of the dynamic pressure bearing portion constituted by the bearing member 1 and the bearing sleeves 21 and 31 as a bearing member is caused by the magnetic force of the annular magnet 13.
3 and is held without leaking out of the motor.

If at least one of the fixed shaft 11 as the shaft member and the bearing sleeves 21 and 31 as the bearing member is made of a magnetic material, abrasion powder generated by the shaft member and the bearing member is reduced. The ring magnet 13 in the communication path B is more reliably attracted to the ring magnet 13.

Further, a magnetic material such as those described in (1) and (3) above is used as the shaft member.
As the bearing member, the above (2) and (4)
When a magnetic material such as, is used, all of the abrasion powder becomes ferromagnetic, so that the annular magnet 13 of the communication path B is used.
Absorption of the abrasion powder is more reliably performed.

If a soft ferrite or sintered ferrite magnet made of ceramic is used as the shaft member or the bearing member as in the above (1), (3) and (4), the mating side can be used. Even if the member is a metal body, it is possible to prevent image sticking due to heat generation due to rotational contact.

Further, as in (3) above, as the shaft member, a non-magnetic material having a higher hardness than the bearing member, for example, a hard ceramic material such as Al ₂ O ₃ or Si ₃ N ₄ or a DLC ( Diamond-like carbon)
When a non-magnetic material having a coating is used, the shaft member has a much higher hardness than the bearing member, so that wear is hardly caused. Further, only the abrasion powder generated from the bearing member, which is a magnetic material, can be attracted to the annular magnet 13 in the communication path B.

Further, as the shaft member, a magnet material is used as in the above (3), and as the bearing member,
Even when the magnet material as described in (4) is used, most of the wear powder generated from the dynamic pressure bearing portion can be adsorbed to the annular magnet 13 in the communication path B.

Further, even if at least the dynamic bearing surface of the bearing member or the shaft member is made of a magnet material or a ferromagnetic material as in (2) and (4) above, Most of the wear powder generated from the pressure bearing portion can be attracted to the annular magnet 13 in the communication path B.

Further, as described above, since the annular magnet 13 in the communication path B is annularly multipolar magnetized (see FIG. 2), most of the wear powder generated from the dynamic pressure bearing portion can be more reliably removed. The ring magnet 13 can be attracted.
Here, the reason why the inner peripheral surface 13a of the annular magnet 13 is multipolarly magnetized is to disperse the attachment of wear powder on the inner peripheral surface 13a as much as possible. Therefore, the smaller the pitch of the multipolar magnetization, the better.

At this time, using a ceramic ferromagnetic material (soft ferrite, sintered ferrite magnet) as in the present embodiment has the following advantages. (1) Even if the member on the other side is a metal body, no seizure due to heat generation due to rotational contact does not occur. (2) Since it has appropriate hardness and is abrasion resistant, generation of abrasion powder is suppressed. (3) Hardness is lower than that of Al ₂ O ₃ , Si ₃ N _4, etc., which are usually high hardness ceramics used as bearings, and grinding is easy. In particular, Al ₂ O ₃ , Si ₃
N _4, it is necessary grinding of expensive diamond grinding wheel by finishing, the material is capable of grinding finish with a relatively inexpensive SiC grinding or BN grindstone and processing speed faster.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof. It goes without saying that the material composition of the bearing member (bearing sleeve) and the shaft member (fixed shaft) may be set in the opposite relationship.

The annular magnet 13 is connected to the communication path B
Need not be arranged over the entire length in the axial direction. Furthermore, the interval between the communication passages B only needs to be set so that at least a part in the axial direction can adsorb the abrasion powder satisfactorily, and it is not necessary to set the entire length to the interval.

Further, in the above-described embodiment, the present invention is applied to a so-called fixed shaft type dynamic pressure bearing device. However, the present invention is similarly applied to a shaft rotating type dynamic pressure bearing device. Can be applied to

[0058]

As described above, according to the first aspect of the present invention, one wall surface of the communication passage between the dynamic pressure bearing portion formed of a pair of dynamic pressure surfaces and the outside is moved from the dynamic pressure bearing surface. It is made of a magnet material that adsorbs the generated abrasion powder, and one wall surface and the other wall surface of the communication path are configured with an interval capable of adsorbing the abrasion powder. The generated abrasion powder can be adsorbed by the magnet material constituting one surface of the communication path, and the cleanliness and durability of the air dynamic bearing device can be improved with a simple configuration.

According to a second aspect of the present invention, at least one of the shaft member and the bearing member according to the first aspect is made of a magnetic material. Thus, it is possible to more reliably attract the magnet surface of the communication path, and the above-described effect can be further enhanced.

Further, according to the third aspect of the present invention, since the magnetic material of the second aspect is made of a magnetic material or a ferromagnetic material, all the wear powder generated from the dynamic pressure bearing surface is strong. Since it becomes a magnetic material, the wear powder can be surely adsorbed by the magnet surface of the communication path, and the above-mentioned effect can be further enhanced.

Further, in the invention according to claim 4, since the magnet material according to claim 3 is constituted by a soft ferrite or a sintered ferrite magnet, the mating member is a metal body. Also, it is possible to prevent the occurrence of image sticking due to heat generation due to the rotating contact, and to improve the reliability in addition to the effect of the invention described in claim 3.

According to a fifth aspect of the present invention, one of the shaft member and the bearing member according to the first aspect is formed of a ferromagnetic material, and the other is formed of the ferromagnetic material. A similar effect can be obtained by using a non-magnetic material having a higher hardness.

Further, even when both the shaft member and the bearing member according to the first aspect are made of a magnetic material, the same effect can be obtained.

Further, according to the seventh aspect of the present invention, the same effect can be obtained even if the magnet material or the ferromagnetic material according to the third aspect is configured to form at least a hydrodynamic bearing surface. it can.

Further, in the invention according to claim 8, since the magnetic material according to claim 1 is subjected to multipolar magnetization in the circumferential direction, wear powder generated from the dynamic pressure bearing surface is removed. In the circumferential direction, it is possible to more reliably attract the magnet surface of the communication passage.

According to a ninth aspect of the present invention, the communication passage according to the eighth aspect is located radially outward with respect to the dynamic pressure bearing surface so as to surround the shaft member and the bearing member. With this configuration, most of the abrasion powder can be reliably attracted to the magnet surface of the communication passage before leaking out of the machine.

Further, the invention according to claim 10 is as follows:
Since the magnet material or the ferromagnetic material according to claim 3 is formed from a ceramic body, it is possible to prevent image sticking due to heat generation due to rotational contact from occurring,
In addition, since it has appropriate hardness and is abrasion resistant, generation of abrasion powder can be suppressed, and since it is relatively low in hardness, it can be easily processed.

[Brief description of the drawings]

FIG. 1 is a sectional explanatory view showing an embodiment of an air dynamic pressure bearing device according to the present invention.

FIG. 2 is an explanatory view showing multipolar magnetization of a cylindrical magnet of the air dynamic pressure bearing device shown in FIG.

FIG. 3 is an explanatory sectional view showing another embodiment of the air dynamic pressure bearing device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator set 2 Rotor set 11 Fixed shaft (shaft member) 11c Radial dynamic pressure generating groove 13 Ring magnet 17 Thrust plate 21 Radial bearing (bearing member) 31 Bearing sleeve (bearing member) 22 Rotating hub 23 Thrust shaft 25 Ring drive magnet

Claims (10)

[Claims] A dynamic pressure bearing portion is formed by opposing a dynamic pressure surface of a shaft member and a dynamic pressure surface of a bearing member rotatably mounted on the shaft member. The two members are rotatably supported by a dynamic pressure action of air interposed in the formed dynamic pressure bearing portion, and a pair of opposed surfaces extending from each of the pair of opposed dynamic pressure surfaces toward the outside of the bearing. In an air dynamic pressure bearing device in which a communication path that connects an open end of the dynamic pressure bearing portion to the outside of the bearing is defined by a wall surface, one of a pair of opposed wall surfaces forming the communication path Is composed of a magnet material that adsorbs the abrasion powder generated from the dynamic pressure bearing portion, and one wall surface and the other wall surface made of the magnet material oppose each other at an interval that enables the attraction of the abrasion powder. The sky characterized by being made Pneumatic bearing device. 2. An air dynamic pressure bearing device, wherein at least one of the shaft member and the bearing member according to claim 1 is made of a magnetic material. 3. The pneumatic bearing device according to claim 2, wherein the magnetic material is a magnetic material or a ferromagnetic material. 4. The pneumatic bearing device according to claim 3, wherein the ferromagnetic material is made of a soft ferrite or a sintered ferrite magnet. 5. One of the shaft member and the bearing member according to claim 1 is made of a ferromagnetic material, and the other side is made of a non-magnetic material having a higher hardness than the ferromagnetic material. An air dynamic pressure bearing device characterized in that: 6. An air dynamic pressure bearing device, wherein both the shaft member and the bearing member according to claim 1 are made of a magnetic material. 7. An air dynamic pressure bearing device, wherein the magnet material or the ferromagnetic material according to claim 3 is used to form at least a dynamic pressure surface. 8. An air dynamic bearing device, wherein the magnetic material according to claim 1 is multipolar magnetized in a circumferential direction. 9. The communication path according to claim 8, wherein the communication path extends radially outward from the dynamic pressure bearing portion and is bent and disposed so as to concentrically surround the shaft member and the bearing member. An air dynamic pressure bearing device characterized by the above-mentioned. 10. An air dynamic pressure bearing device, wherein the magnet material or the ferromagnetic material according to claim 3 is formed of a ceramic body.