JPH1137143A - Gaseous type dynamic pressure bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent pollution of a disk by maintaining a drive space D clean in a simple structure. SOLUTION: This device is provided with a setup space of a rotational driving source, and an air circulating passage to feed a dynamic pressure gas to a radial gaseous dynamic pressure bearing part 22 and a trust gaseous dynamic pressure bearing part 23 interrupted by a space interrupting means 36, and it is also provided with an air passage 30 interconnecting this air circulating passage to an outer end of a stationary shaft 13, installing a dust collecting means 35 in this air passage 30. With this constitution, dust such as abrasive powder produced in the dynamic pressure bearing part is not discharged into a drive space D maintained clean.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas dynamic pressure bearing device which supports rotation by a gas dynamic pressure effect in an opposing gap between a fixed shaft and a bearing member.

[0002]

2. Description of the Related Art Hitherto, various kinds of rotating devices have been studied and proposed to employ a dynamic pressure bearing device utilizing dynamic pressure of a fluid. Among them, the gas-type dynamic pressure bearing is provided with a gas dynamic pressure bearing portion in an opposing gap between the fixed shaft and the bearing side member, and gas such as air introduced into the gas dynamic pressure bearing portion is acted by a dynamic pressure generating groove. The pressure is increased to generate a dynamic pressure, and the bearing side member is rotatably supported on the fixed shaft by the gas dynamic pressure action. The gas-type hydrodynamic bearing device includes a type in which gas flows in one direction from one end to the other end in the radial gas bearing portion, and a type in which a radial gas bearing portion branches from a substantially central position to both ends. There are things where gas flows in such a way.

In such a gas type dynamic pressure bearing device,
For example, JP-A-1-288611, JP-A-2-2-1
As described in JP-A No. 1918, JP-A-2-113113, etc., a filter as a dust collecting means is provided in a gas intake hole to capture dust which is going to enter the apparatus, and a dynamic pressure due to dust mixing is provided. There have been proposals for preventing the seizure of the bearing portion.

[0004]

However, such a conventional apparatus cannot be immediately applied to a rotating apparatus requiring a high clean environment, such as a hard disk drive (HDD) motor. For example, in the case of a hard disk drive (HDD) motor, if dust adheres to the disk surface, it may cause a reproduction error or a head crash. Therefore, the entire device is stored in a drive space maintained in a highly clean environment. .

However, in the above-mentioned gas-type dynamic pressure bearing device, since the bearing portion comes into contact immediately after the start of rotation or when the rotation is stopped, dust due to contact wear is discharged from the dynamic pressure bearing portion into the drive space. Become. The discharged dust may contaminate the disk.

Immediately after the start of rotation, the disk may be charged by friction due to the head being in contact with the surface of the disk. Is in a non-contact state, so that the disk side cannot be grounded. Therefore, the charged charges generated on the disk cannot be removed by the ground, and the head may be damaged.

Accordingly, the present invention has a simple structure, which is capable of purifying exhaust gas to the drive space to prevent contamination, and enabling the disk to be discharged even during rotation. An object of the present invention is to provide a pressure bearing device.

[0008]

In order to achieve the above object, in a gas dynamic pressure bearing device according to the present invention, a bearing-side member is provided so as to face a fixed shaft, and the fixed shaft is provided. A radial gas dynamic pressure bearing portion and a thrust gas dynamic pressure bearing portion are provided in an opposing gap between the bearing and the bearing side member, and the gas in the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion is pressurized by dynamic pressure generating means. In the gas dynamic pressure bearing device, a bearing-side member is rotatably supported with respect to the fixed shaft by the gas dynamic pressure effect, and is rotationally driven by a predetermined rotary drive source. The radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion are cut off from a space in which the rotary drive source is disposed by a predetermined space shutoff means. The gas dynamic pressure bearing portion is configured so that gas moves from one side to the other side, and the moving gas is moved between the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion. A gas circulation path for circulating the gas is provided, the fixed shaft is provided with an air passage communicating the gas circulation path to the outer end of the fixed shaft, and the gas circulation path or the air passage is provided with dust collecting means. .

Further, in the gas dynamic pressure bearing device according to the second aspect of the present invention, the gas pressure increasing effect of the dynamic pressure generating means according to the first aspect is provided by a radial gas dynamic pressure bearing portion and a thrust gas dynamic pressure bearing portion. The gas is biased to flow from one side to the other side.

Further, in the gas dynamic pressure bearing device according to the third aspect of the present invention, the space blocking means according to the first aspect comprises a magnetic fluid seal using a conductive magnetic fluid,
The magnetic fluid seal is provided between the fixed shaft and the bearing-side member, the fixed fluid and the bearing-side member are electrically connected by the magnetic fluid seal, and the bearing-side member is connected to the magnetic fluid seal and the fixed shaft. Through the ground.

Further, in the gas dynamic pressure bearing device according to the present invention, the bearing member according to the first aspect is a disk hub for holding a disk, and a thrust gas is provided at one end of the fixed shaft. A dynamic pressure bearing portion is formed, and a stator constituting a motor drive portion is attached to the other end of the fixed shaft.

Further, in the gas dynamic pressure bearing device according to the fifth aspect of the present invention, the entire device according to the first aspect is disposed in a drive space in which a clean gas is held in a substantially closed case.

[0013] According to such an apparatus of claim 1,
The gas circulating between the radial gas dynamic pressure bearing and the thrust gas dynamic pressure bearing flows in a state where it is cut off from the space in which the rotary drive source is arranged. Dust is not discharged to the space where the rotary drive source is arranged. Further, when a pressure fluctuation occurs in the radial gas dynamic pressure bearing portion or the thrust gas dynamic pressure bearing portion, the pressure fluctuation corresponding to the pressure fluctuation between the gas dynamic pressure bearing portion and the space outside the fixed shaft. Gas is to be taken in and out.

According to the second aspect of the present invention, the gas is caused to flow by the dynamic pressure generating means having a biased pressurizing action.

Further, according to the gas dynamic pressure bearing device of the third aspect, the bearing-side member that rotates while holding a recording medium such as a disk is provided through a magnetic fluid seal using a conductive magnetic fluid. Since power is supplied to the grounded fixed shaft side, the static charge generated on the recording medium can be satisfactorily removed even during rotation.

According to the present invention, the gas-type dynamic pressure bearing device according to the fourth aspect of the present invention and the gas-type dynamic pressure bearing device according to the fifth aspect of the present invention are arranged in a drive space having a clean gas. It is particularly preferably obtained in a pressure bearing device.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a spindle motor for driving a hard disk (for an HDD) will be described below in detail with reference to the drawings.

The HDD spindle motor shown in FIG. 1 is a so-called single-bag outer rotor type. First, the overall structure will be described. This HDD spindle motor is disposed in a drive space D partitioned by a substantially sealed drive case C in order to ensure cleanliness. The drive space D is communicated with outside air through a dust collection filter (not shown), and is always maintained in a clean air environment. Hereinafter, the structure of the motor housed in the drive space D will be described below.

First, the illustrated HDD spindle motor includes a stator set 1 as a fixed member, and a rotor set 2 as a rotating member assembled to the stator set 1 from above in the figure. The stator set 1 has a frame 11 screwed to the above-mentioned fixed base side of the drive case C, and a support holder 12 provided at a substantially central portion of the frame 11.
Inside, a fixed shaft 13 is erected so as to extend upward in the figure.

A stator core 14 is fitted on the outer periphery of the support holder 12 on the frame 11, and a winding 15 is wound around salient poles of the stator core 14.

On the other hand, the rotor set 2 has a hub body 21 for supporting a recording medium (not shown). The hub body 21 is rotatably supported on the outer peripheral side of the fixed shaft 13 via a radial air dynamic pressure bearing 22 and a thrust air dynamic pressure bearing 23 described later. The hub body 21 has a substantially cylindrical body 21a for mounting a magnetic recording medium such as a magnetic disk on the outer periphery thereof, and a mounting annular flange provided at a shaft end opening of the body 21a. A rotor magnet 26 is annularly mounted on the portion 21b via a back yoke 25. The annular rotor magnet 26 is formed by the stator core 14 described above.
Are arranged circumferentially close to each other so as to face the outer peripheral end face thereof via a predetermined minute gap in the radial direction.

The back yoke 25 is made of an annular magnetic member having a substantially inverted L-shaped cross section, and is fixed so as to be in close contact with the lower surface of the mounting annular flange portion 21b of the hub body 21 in the figure. The rotor magnet 26 is formed of a ring-shaped member having a substantially rectangular cross section made of a rare-earth bonded magnet, a sintered magnet, or the like, and is provided on the inner peripheral side of the inverted L-shaped cross section of the back yoke 25. It is mounted so as to fit.

The above-described radial pneumatic dynamic bearings 22 are provided in a pair in the axial direction. The two pneumatic dynamic pressure surfaces provided on the outer peripheral surface of the fixed shaft 13 and the hub body 21 as a bearing-side member are provided. Two air dynamic pressure surfaces provided on the inner peripheral surface are opposed to each other in a radial direction with a predetermined small gap therebetween.

At this time, the lower end portion 22a of the minute gap in the radial air dynamic pressure bearing 22 on the lower side in the figure is opened above the radially inner portion of the stator 14 as a motor drive portion constituting a rotary drive source. The lower end opening portion 2 of the radial air dynamic pressure bearing 22 is disposed.
The motor drive unit and the drive space D that constitute the rotary drive source are isolated from each other by a magnetic fluid seal 36 as a space isolation unit provided immediately below the position 2a. The structure of the magnetic fluid seal 36 will be described later.

Further, at least one of the air dynamic pressure surface on the fixed shaft 13 side and the air dynamic pressure surface on the hub body 21 side has
For example, a number of spiral-shaped dynamic pressure generating grooves (not shown) are formed so as to be arranged side by side in the circumferential direction, and a dynamic pressure is applied to the air in the minute gap by the pumping action of these dynamic pressure generating grooves during rotation. And the hub body 21 is rotatably supported in the radial direction with respect to the fixed shaft 13 by the air dynamic pressure effect.

At this time, the radial air dynamic pressure bearing 22
The dynamic pressure generating groove provided as a dynamic pressure generating means has an unbalanced groove shape so that air pressurized from the radial air dynamic pressure bearing portion 22 toward the thrust air dynamic pressure bearing portion 23 flows. The flow of air is caused to flow in one direction due to the bias of the pressurizing action based on the unbalanced groove shape.

Further, a disc-shaped thrust plate 27 is screw-fixed to the opening at the upper end in the figure of the hub 21 so as to seal the opening of the hub 21. The illustrated lower surface of the thrust plate 27 is disposed so as to face the tip end surface (the upper end surface in the drawing) of the fixed shaft 13 in the axial direction, and these axially opposed surfaces are formed on the air dynamic pressure surface, respectively. A thrust air dynamic pressure bearing portion 23 is configured.

An outer peripheral portion of the thrust air dynamic pressure bearing portion 23 opposed to both dynamic pressure surfaces is connected so as to be in communication with the minute gap in the radial air dynamic pressure bearing portion 22 described above. Air is sent from the air dynamic pressure bearing portion 22 to the portion facing the dynamic pressure surface of the thrust air dynamic pressure bearing portion 23 and is boosted, whereby the hub body 21 is rotatably supported in the thrust direction while floating in the axial direction. It is configured as follows.

As the air pressure increasing means in the thrust air dynamic pressure bearing portion 23, the above-described radial air bearing portion 2 is used.
The groove for dynamic pressure generation may be the same as that of 2, or an axial projection may be provided on at least one of the thrust plate 27 side and the fixed shaft 13 side, and the projection may use a boosting effect by a so-called wedge effect. May be.

The air pressure increasing means in the thrust air dynamic pressure bearing portion 23 is formed in an unbalanced groove shape so as to flow the pressurized air from the outer peripheral side toward the center side. The flow of air is performed in one direction due to the bias of the pressurizing action based on the groove shape.

The flow of air in the thrust air dynamic pressure bearing portion 23 is set so as to go from the outer peripheral side communicating with the radial air bearing portion 22 to the center side. Air holes 13a provided
Through, the exhaust air from the thrust air dynamic pressure bearing portion 23 side flows into the fixed shaft 13. That is, an air passage 30 constituting an air circulation passage is provided in the center portion of the fixed shaft 13 so as to penetrate in the axial direction. It is communicated with the dynamic pressure bearing portion 23 side.

An air hole 32 is provided substantially horizontally below the illustrated portion of the air passage 30 provided in the fixed shaft 13 so as to penetrate the fixed shaft 13 in the diameter direction. A radially inner end portion of the air hole 32 is opened to the air passage 30, and a radially outer end portion of the air hole 32 is opened to a radially inner space portion of the stator 14. The radial gas dynamic pressure bearing portion 22 communicates with the lower end opening 22a shown in the figure.

The space where the air hole 32 on the fixed shaft 13 side communicates with the radial gas dynamic pressure bearing portion 22 is:
The magnetic fluid seal 36 blocks the motor drive unit and the drive space D that constitute a rotary drive source. That is, the magnetic fluid seal 36 is disposed directly below the air hole 32 of the fixed shaft 13 and the radial gas dynamic pressure bearing portion 22 in the drawing, and is provided with an annular permanent magnet 36 a fixed to the inner wall side of the hub body 21. A pair of pole pieces 36b, 36b are attached substantially in parallel on both end surfaces of the pair, and the conductive magnetic fluids 36c, 36c held on the inner peripheral edges of the pair of pole pieces 36b, 36b are:
It is attracted to the outer peripheral surface of the fixed shaft 13.

At this time, the fixed shaft 13 and the hub 21 as a bearing member are electrically connected by the magnetic fluid seal 36, and the fixed shaft 13
Is grounded to ground the hub body 21 and the disk held by the hub body 21.

A filter 33 as a dust collecting means is disposed at an opening portion on the radially outer side of the air hole 32, and dust in the air passing through the air passage 30 of the fixed shaft 13 is removed. The air captured and purified by the filter 33 is taken into the radial gas dynamic pressure bearing portion 22.

Further, a lid 31 is fitted from the lower side in the drawing to an opening provided at the lower outer end of the air passage 30 of the fixed shaft 13 in the drawing, and is penetrated through the lid 31. The air passage 30 is communicated with the motor drive unit constituting the rotary drive source and the space E on the outside of the drive space D by the provided communication hole 34. The air passage 3 of the communication hole 34 provided in the lid 31
A filter 35 as a dust collecting means is disposed in the opening on the upper end side of FIG.
Dust in the air that enters and exits between the inside of the drive space D and the external space E of the drive space D is captured and cleaned by the filter 35.

As described above, in the present embodiment, the radial air dynamic pressure bearing portion 22 and the thrust air dynamic pressure bearing portion 23 are connected to the air hole 13a of the fixed shaft 13, the air passage 30 and the air hole 32.
An air circulation path is provided so as to connect
The air for generating the dynamic pressure flows in one direction through the air circulation path as shown by arrows in the figure.

Further, the air circulation path is shut off from the motor drive section and the drive space D which constitute a rotary drive source by the magnetic fluid seal 36, and the air is excessive or insufficient due to pressure fluctuations in the air circulation path. Is generated, air flows in and out between the air circulation path and the motor drive unit and the external space E of the drive space D through the air passage 30 and the like.

According to such an apparatus according to the present embodiment, the gas circulating between the radial air dynamic pressure bearing portion 22 and the thrust air dynamic pressure bearing portion 23 is supplied to the motor driving portion and the motor driving portion constituting the rotary driving source. Since the fluid flows while being blocked from the drive space D, dust such as abrasion powder generated in the dynamic pressure bearing is not discharged to the cleaned drive space D. Therefore, the inside of the drive space D is always kept clean, and the rotation drive is performed without causing contamination of the disk or the like.

At this time, since clean air is passed through the filter 33 to the radial air dynamic pressure bearing 22, the occurrence of seizure of the radial air dynamic pressure bearing 22 is prevented.

Further, according to the present embodiment, the hub body 21 made of the conductive material on the rotating side holding the disk is fixed to the hub body 21 made of the conductive material via the magnetic fluid seal 36 using the conductive magnetic fluid. By being electrically connected to the shaft 13 and grounding the fixed shaft 13, the hub body 21 and the disk held by the hub body 21 are always maintained in a grounded state. Therefore, the electric charge of the charged electric charge generated on the disk can be removed satisfactorily even during the rotation, and the electrical protection of the head is performed.

Next, the embodiment shown in FIG. 2 applies the present invention to a so-called fixed-end type HDD spindle motor, and has the same configuration as that shown in FIG. The members having the same reference numerals are given the same reference numerals, and the description thereof is omitted.

In the HDD spindle motor shown in FIG. 2, the upper and lower ends of the fixed shaft 63 are screwed and fixed to a substantially sealed drive case C, and fitted to the outside of the fixed shaft 63. An air dynamic pressure surface formed at two locations on the outer peripheral surface of the bearing sleeve 60 separated by a predetermined distance in the axial direction, and two air dynamic pressure surfaces provided on the inner peripheral surface of the hub body 21 as a bearing-side member. Are radially opposed to each other with a predetermined minute gap therebetween, and two radial air dynamic pressure bearings 62 are provided at predetermined intervals in the axial direction.

At this time, a portion just below the lower end surface of the radial air dynamic bearing 62 on the lower side of the figure is provided between the circulation path of the pressurized air and the motor drive section and the drive space D constituting the rotary drive source. A magnetic fluid seal 65 for shutting off is provided. In the sexual fluid seal 65, a pair of pole pieces 65b, 65b are attached substantially in parallel on both end faces of an annular permanent magnet 65a fixed to the inner wall side of the hub body 21, and the pair of pole pieces 65b, Conductive magnetic fluids 65c, 65c held at the inner peripheral edge of 65b
Is adsorbed on the outer peripheral surface of the fixed shaft 63.

The magnetic fluid seal 65 electrically connects the fixed shaft 13 and the hub 21 as a bearing-side member, and the fixed shaft 13 is grounded so that the hub 21 , And the disk held by the hub body 21 is grounded.

A seal plate 66 is provided so as to cover the magnetic fluid seal 65 from the outside (the lower side in the figure). The seal plate 66 is provided with the magnetic fluid seal 6 described above.
Even if it is damaged, it functions to prevent dust such as abrasion powder from coming out of the motor, and the outer peripheral portion of the seal plate 66 is fixed to the hub body 21 side. , Its inner peripheral portion is arranged close to the fixed shaft 63.

On at least one of the air dynamic pressure surface on the bearing sleeve 60 side and the air dynamic pressure surface on the hub body 21 side as a bearing-side member, for example, a spiral-shaped dynamic pressure generating groove not shown is formed. Are formed in parallel with each other in the direction, and a dynamic pressure is generated in the air in the minute gap by the pumping action of these dynamic pressure generating grooves during rotation, and the hub body 2 is formed by the air dynamic pressure action.
1 is configured to be supported rotatably in the radial direction with respect to the fixed shaft 63.

At this time, the radial air dynamic pressure bearing 62
The dynamic pressure generating groove provided as a dynamic pressure generating means is unbalanced so that air pressurized from the radial air dynamic pressure bearing portion 62 toward a thrust air dynamic pressure bearing portion 61 described later flows. It is formed in a groove shape, and the flow of air is performed in one direction due to the bias of the pressurizing action based on the unbalanced groove shape.

Further, a substantially disc-shaped thrust plate 67 is fixed to the opening on the upper end side of the hub body 21 in the drawing, and the center hole of the thrust plate 67 is fixed to the fixed shaft 6.
3 is arranged so as to penetrate the illustrated upper end portion. The gap between the outer peripheral surface of the fixed shaft 63 projecting upward from the thrust plate 67 and the center hole of the thrust plate 67 is closed by a magnetic fluid seal 68.

That is, the magnetic fluid seal 68 is attached to the upper surface of the thrust plate 67, and a pair of pole pieces are attached on both end surfaces of the annular permanent magnet in a substantially parallel manner. The conductive magnetic fluid 68 c held on the inner peripheral edge of the piece is adsorbed on the outer peripheral surface of the fixed shaft 63.

The magnetic fluid seal 68 electrically connects the fixed shaft 63 and the hub body 21 as a bearing-side member, and the fixed shaft 63 is grounded so that the hub body 21 is grounded. Is configured to be grounded.

A seal plate 69 is provided so as to cover the magnetic fluid seal 68 from the outside (the upper side in the figure). The seal plate 69 is provided with the magnetic fluid seal 6 described above.
Even if the 6 is damaged, it functions so that dust such as abrasion powder does not come out of the motor. The outer peripheral portion of the seal plate 69 is fixed to the thrust plate 67 side. , Its inner peripheral portion is arranged close to the fixed shaft 63.

On the other hand, the illustrated lower surface of the thrust plate 67 is
The bearing sleeve 60 is disposed so as to face the end surface (the upper surface in the drawing) in the axial direction, and these two axially facing surfaces are formed on the air dynamic pressure surfaces, respectively, to form a thrust air dynamic pressure bearing portion 61. I have.

The outer peripheral portion of the thrust air dynamic pressure bearing 61 opposed to the two dynamic pressure surfaces is connected so as to be in communication with the minute gap of the radial air dynamic pressure bearing 62 described above. The air is sent from the air dynamic pressure bearing portion 62 to the space between the dynamic pressure opposing surfaces of the thrust air dynamic pressure bearing portion 61 and the pressure is raised, so that the hub body 21 is supported in the axial direction and rotatably in the thrust direction. It is configured to be.

The air pressure increasing means in the thrust air dynamic pressure bearing 61 at this time may be a dynamic pressure generating groove similar to the radial air bearing 62 described above, or may be the thrust plate 67 side or the fixed shaft 63. It is also possible to provide an axial projection on at least one of the sides, and use the boosting effect of the axial projection by a so-called wedge effect.

The air pressure increasing means in the thrust air dynamic pressure bearing portion 61 is formed in an unbalanced groove shape so as to flow the pressurized air from the outer peripheral side toward the center side. The flow of air is performed in one direction due to the bias of the pressurizing action based on the groove shape.

Further, the flow of air in the thrust air dynamic pressure bearing portion 61 is from the outer peripheral side communicating with the radial air bearing portion 62 to the center side, but is provided on the inner peripheral side of the bearing sleeve 60. Through the air passage 70 as an air circulation passage, air from the thrust air dynamic pressure bearing portion 61 flows from the opening 70 a at the illustrated lower end portion of the air passage 70 to the space above the illustrated magnetic fluid seal 65. It is configured to be discharged.

At this time, a filter 73 as dust collecting means is disposed in the illustrated lower end opening portion 70a of the air passage 70, and dust in the air passing through the air passage 70 is filtered by the filter 73. The trapped and purified air flows into the radial air dynamic bearing 62.

A branch passage 71 a from the air passage 71 provided in the fixed shaft 63 is opened at an intermediate portion of the air passage 70 provided on the inner peripheral side of the bearing sleeve 60. That is, at the center of the fixed shaft 63,
An air passage 71 constituting an air circulation passage is provided so as to penetrate in the axial direction, and an upper end portion of the air passage 71 in the drawing communicates with the air passage 70 on the thrust air dynamic pressure bearing portion 61 side as described above. Have been.

The lower end of the air passage 71 of the fixed shaft 63 is communicated with a motor drive unit constituting a rotary drive source and a space E on the outside of the drive space D. A filter 74 as dust collecting means is disposed in the opening of the filter. As a result, dust in the air flowing in and out between the air passage 71 of the fixed shaft 63 and the motor drive unit and the external space E of the drive space D constituting the rotary drive source is captured by the filter 74 and cleaned. Be transformed into

As described above, also in the present embodiment, the air circulation path is provided by connecting the radial air dynamic pressure bearing portion 62 and the thrust air dynamic pressure bearing portion 61 by the air passage 70 provided in the bearing sleeve 60. The air for generating dynamic pressure flows in one direction through the air circulation path as indicated by the arrow in the drawing.

Further, the air circulation path is cut off from the motor drive section and the drive space D side constituting the rotary drive source by the magnetic fluid seal 65, and the air flow is increased due to pressure fluctuations in the air circulation path. When the shortage occurs, the air flows in and out between the air circulation path and the motor drive unit and the external space E of the drive space D through the air passages 70 and 71 and the like. ing.

That is, also in the device according to the present embodiment, the gas circulating between the radial air dynamic pressure bearing portion 62 and the thrust air dynamic pressure bearing portion 61 is supplied to the motor drive portion and the drive space constituting the rotary drive source. Since the fluid flows in a state in which it is cut off from D, dust such as abrasion powder generated in the dynamic pressure bearing is not discharged to the cleaned drive space D. Therefore, the inside of the drive space D is always kept clean, and the rotation drive is performed without causing contamination of the disk or the like.

At this time, since clean air is sent through the filter 73 to the radial air dynamic pressure bearing 61, seizure of the radial air dynamic pressure bearing 62 is prevented.

Further, according to the present embodiment, the rotating hub body 21 holding the disk is always kept in the grounded state via the magnetic fluid seal 65 using a conductive magnetic fluid. Elimination of the generated charge is performed well even during rotation, and electrical protection of the head is performed.

In the embodiment shown in FIGS. 2A and 2B, a seal projection 67a close to the outer periphery of the fixed shaft 63 is formed integrally with the inner periphery of the hole of the thrust plate 67, and the inner periphery of the seal projection 67a is formed. A so-called labyrinth seal for protecting the magnetic fluid seal 68 is formed in the portion.
Such a labyrinth seal can be arranged directly above the lower magnetic fluid seal 65 described above.

The HDD motor shown in the embodiment shown in FIG. 3 has a basic structure similar to that of the apparatus shown in FIG. 2 described above. The same reference numerals are given and the description is omitted, and different points will be described.

A communication hole 70 b extending in the radial direction from the air passage 70 is formed in a substantially central portion in the axial direction of the bearing sleeve 60.
Are formed so as to penetrate the bearing sleeve 60 substantially horizontally, and the communication hole 70b allows the air passage 70 to pass therethrough.
Of the two radial air dynamic pressure bearings 62
It is connected to the part between.

For the radial air dynamic bearing 62 disposed on the lower side in the figure, a thrust plate 67 'similar to the thrust plate 67 provided for the upper radial air dynamic bearing 62 is provided. The lower thrust air dynamic pressure bearing 61 ′ is formed on the lower side.

A dynamic pressure generating groove provided as a dynamic pressure generating means in the radial air dynamic pressure bearing 62 on the upper side of the drawing is
The unbalanced groove shape is formed so that the air pressurized from the radial air dynamic pressure bearing portion 62 toward the upper thrust air dynamic pressure bearing portion 61 in the drawing flows. The air flow is caused to flow in one direction toward the upper side in the figure due to the bias of the pressurizing action based on the pressure. Further, a dynamic pressure generating groove provided as a dynamic pressure generating means on the lower radial air dynamic pressure bearing 62 in the drawing is provided from the radial air dynamic pressure bearing 62 to the lower thrust air dynamic pressure bearing 61 in the drawing. It is formed in an unbalanced groove shape so as to make the air pressurized toward it flow, and the flow of air flows in one direction toward the lower side in the figure due to the bias of the pressurizing action based on the unbalanced groove shape. It has become.

On the other hand, the air pressure raising means in the thrust air dynamic pressure bearing 61 is formed in an unbalanced groove shape so as to flow the pressurized air from the outer peripheral side toward the center side. The flow of air is performed by the bias of the pressurizing action based on the balanced groove shape.

The upper thrust air dynamic pressure bearing 6
1 and the air discharged from the lower thrust air dynamic pressure bearing 61 ′ is returned to the upper and lower radial air dynamic pressure bearings 62, 62 side through the air passage 70 and the communication hole 70 b. This forms an air circulation path. In such an embodiment, the same operation and effect as those in the above embodiment can be obtained.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say.

For example, in the above-described embodiment, the present invention is applied to an HDD motor, but the present invention is not limited to this, and is similarly applied to various types of rotating devices. be able to. Further, the present invention is not limited to the fixed shaft type as in the above-described embodiment, but can be similarly applied to a shaft rotating type.

In each of the above-described embodiments, the pressurized air is caused to flow from the radial air dynamic pressure bearing toward the thrust air dynamic pressure bearing. It is also possible to make the pressurized air flow from the bearing to the radial air dynamic pressure bearing.

Further, the present invention is not limited to air as described above, and can be similarly applied to an apparatus using another gas.

[0077]

As described above, according to the first aspect of the present invention, one side of the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion which are cut off from the space in which the rotary drive source is disposed by the space cutoff means. By providing a gas circulation path for flowing the dynamic pressure gas toward the other side and providing a dust collecting means in an air passage or a gas circulation path that communicates the gas circulation path to the outer end of the fixed shaft, the dynamic pressure is increased. The drive space can be kept clean with a simple structure because dust and other dust generated in the bearings are not discharged to the cleaned drive space. And the like can be prevented, and the reliability of the gas dynamic pressure bearing device can be improved.

Further, if the dynamic pressure generating means is provided with a biased pressurizing action to cause the dynamic pressure gas to flow, the gas can be circulated with a simple structure. And the effect described above can be enhanced.

Further, as in the third aspect of the present invention, the gas circulation path is cut off from the drive space by a magnetic fluid seal using a conductive magnetic fluid, and the fixed shaft and the bearing side member are electrically connected. If the bearing-side member is grounded, the disk can be neutralized even during rotation, and in addition to the above-described effects, electrical damage of the head can be satisfactorily prevented. Reliability can be further improved.

This effect is achieved by the gas-type dynamic pressure bearing device according to claim 4, wherein the bearing-side member is a disk hub, and the gas-type dynamic pressure bearing device according to claim 5, wherein the device is disposed in a drive space containing clean gas. In a pressure bearing device, it is particularly preferably obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing a structure of an HDD spindle motor having a gas dynamic pressure bearing device according to an embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view showing a structure of an HDD spindle motor having a gas dynamic pressure bearing device according to another embodiment of the present invention.

FIG. 3 is an explanatory cross-sectional view showing a structure of an HDD spindle motor having a gas dynamic pressure bearing device according to still another embodiment of the present invention.

[Explanation of symbols]

 13, 63 Fixed shaft 22, 62 Radial air dynamic pressure bearing 23, 61 Thrust air dynamic pressure bearing 30, 71 Air passage 33, 70c, 73, 74 Filter (dust collecting means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazushi Miura 5329 Shimosuwa-cho, Suwa-gun, Nagano Prefecture Inside Sankyo Seiki Seisakusho Co., Ltd.

Claims (5)

[Claims] 1. A bearing member is provided so as to face a fixed shaft, and a radial gas dynamic pressure bearing portion and a thrust gas dynamic pressure bearing portion are provided in a gap between the fixed shaft and the bearing member. The gas in the gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion is pressurized by the dynamic pressure generating means to generate a dynamic pressure effect, and the bearing side member is rotatably supported with respect to the fixed shaft by the gas dynamic pressure effect. Then, in the gas dynamic pressure bearing device configured to be rotationally driven by a predetermined rotary drive source, the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion are fixed with respect to an arrangement space of the rotary drive source. And the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion are configured so that the gas moves from one side to the other side, and A gas circulation path for circulating the gas to be circulated between the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion, and air for communicating the gas circulation path to the fixed shaft to an outer end of the fixed shaft. A gas type dynamic pressure bearing device, wherein a passage is provided, and dust collecting means is provided in the gas circulation path or the air passage. 2. The gas pressure increasing function of the dynamic pressure generating means according to claim 1 is biased so that gas flows from one side of the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion to the other side. A gas dynamic pressure bearing device characterized by having a configuration as described above. 3. The space shut-off means according to claim 1, comprising a magnetic fluid seal using a conductive magnetic fluid, wherein the magnetic fluid seal is provided between a fixed shaft and a bearing-side member. Wherein the fixed shaft is electrically connected to a bearing-side member, and the bearing-side member is grounded via the magnetic fluid seal and the fixed shaft. 4. A bearing member according to claim 1, wherein said bearing member is a disk hub for holding a disk, wherein a thrust gas dynamic pressure bearing portion is formed at one end of a fixed shaft, and a motor is provided at the other end of said fixed shaft. A gas dynamic pressure bearing device, wherein a stator constituting a drive unit is mounted. 5. A gas dynamic pressure bearing device, wherein the entire device according to claim 1 is arranged in a drive space in which a clean gas is held in a substantially sealed case.