JPH1137144A - Gaseous type dynamic pressure bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent pollution of a disk by purifying discharge gases into a drive space D in a simple structure. SOLUTION: This device is provided with a gas circulating passage allowing a dynamic pressure gas to flow toward the other side from one side between a radial gas dynamic pressure bearing part 22 and a thrust gas dynamic pressure bearing part 23, while a dust collecting means 32 is set up in the gas circulating passage. With this constitution, any dust in the gas to be discharged out of the gas dynamic pressure bearing parts is collecting means 32, and thereby air contaminated by abrasive powder is not discharged into a drive space D.

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.

[0006] Immediately after the start of rotation, the disk may be charged by friction due to the head being in contact with the disk surface. Is in non-contact with the fixed side, 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. A dynamic gas pressure generating apparatus, wherein the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing are provided in a gas dynamic pressure bearing device in which the bearing side member is rotatably supported with respect to the fixed shaft by the gas dynamic pressure action. And a gas circulating between the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion, while the gas is moved from one side to the other side. The circulation path is provided, it is arranged dust collecting means in the middle of the gas circulation path.

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 gas circulation return path according to the first aspect includes a gas passage provided inside the fixed shaft.
Dust collecting means is provided in the gas passage in the fixed shaft.

Further, in the gas dynamic pressure bearing device according to the present invention, a magnetic fluid seal using a conductive magnetic fluid is provided between the fixed shaft and the bearing-side member. The fixed shaft and the bearing-side member are electrically connected by a magnetic fluid seal, and the bearing-side member is grounded via the magnetic fluid seal and the fixed shaft.

In the gas dynamic pressure bearing device according to a fifth aspect of the present invention, the bearing-side member according to the first aspect is characterized in that:
A disk hub for holding a disk. A thrust gas dynamic pressure bearing is formed at one end of a fixed shaft, and a stator constituting a motor drive unit is attached to the other end of the fixed shaft.

Further, in the gas dynamic pressure bearing device according to the invention described in claim 6, the entire device described in claim 1 is constructed as follows.
It is arranged in a drive space that holds a clean gas in a substantially sealed case.

Further, in the gas dynamic pressure bearing device according to the invention of claim 7, the clean gas in the drive space according to claim 6 is sucked into the radial gas dynamic pressure bearing portion so that the thrust gas dynamic pressure bearing portion. A gas circulation path is constituted by a gas circulation forward path to be sent to the air passage and a gas circulation return path for discharging gas in the thrust gas dynamic pressure bearing portion to the drive space side.

[0015] According to such an apparatus of claim 1,
Dust in the gas discharged from the radial gas dynamic pressure bearing portion through the thrust gas dynamic pressure bearing portion is trapped by the dust collecting means, so that air contaminated by abrasion powder and the like is not discharged into the cleaned drive space. It has become.

Further, 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.

According to the third aspect of the present invention, dust in the gas flowing from the radial gas dynamic pressure bearing portion through the thrust gas dynamic pressure bearing portion into the gas passage of the fixed shaft is captured by the dust collecting means. So that contaminated air is not discharged from the gas passage.

Further, according to the gas dynamic pressure bearing device of the fourth aspect, the bearing-side member that rotates while holding a recording medium such as a disk is connected via a magnetic fluid seal using a conductive magnetic fluid. Because the fixed shaft side that is grounded is energized,
It is possible to satisfactorily remove static charges generated in the recording medium even during rotation.

The gas-type dynamic pressure bearing device according to claim 5, wherein the bearing side member is a disk hub, and the gas-type dynamic pressure bearing device according to claim 6, wherein the device is arranged in a drive space containing clean gas. It is particularly preferably obtained in a pressure bearing device.

Further, when the apparatus is arranged in the drive space having the clean gas, the dynamic pressure gas is circulated through the gas circulation forward path and the gas circulation return path as in the apparatus according to the seventh aspect. It has become.

[0021]

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 type 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 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 formed 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 illustrated lower surface of the mounting annular flange portion 21b of the hub body 21. 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 air dynamic bearings 22 are provided in a pair in the axial direction. Two radial air dynamic pressure surfaces provided on the outer peripheral surface of the fixed shaft 13 and a 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 drawing is arranged so as to open above the radially inner portion of the stator 14 constituting the above-described motor driving portion. And clean air discharged through a gap between the stator set 1 and the rotor set 2 constituting the motor drive section from an outlet of an air circulation path in the motor to be described later through the dust collecting means, or the drive space. The clean air in D is sent into the minute gap of the radial air dynamic pressure bearing 22.

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 performed by the bias of the pressurizing action based on the unbalanced groove shape.

Further, a disc-shaped thrust plate 27 is screw-fixed to the upper end opening of the hub 21 in the figure 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.

The outer peripheral portion of the thrust air dynamic bearing portion 23 opposed to the two 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. The lower end portion of the air passage 30 in the figure is hermetically closed and closed by a lid 31 fitted into the air passage 30 from the lower side in the figure while communicating with the dynamic pressure bearing portion 23 side.

An air discharge passage 32 is provided below 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 discharge passage 32 is open to the air passage 30, and a radially outer end portion of the air discharge passage 32 is formed in a radial direction of the stator 14 constituting the above-described motor drive unit. The drive space D is opened to the inner space, and communicates with the inside of the drive space D through a gap between the stator set 1 and the rotor set 2.

At this time, a filter 33 as a dust collecting means is arranged at an opening portion on the radially outer side of the air discharge passage 32, and the dust in the air passing through the air passage 30 of the fixed shaft 13. However, air trapped by the filter 33 and contaminated by abrasion powder or the like generated in the dynamic pressure bearing portion is not discharged to the cleaned motor drive portion and the drive space.

As described above, in this embodiment, the air circulation outward path is provided so as to connect the radial air dynamic pressure bearing portion 22 and the thrust air dynamic pressure bearing portion 23 from the motor drive portion communicating with the drive space D. And drive space D
After the clean air inside is sucked into the radial air dynamic pressure bearing portion 22 via the motor drive portion, as shown by the arrow in the drawing, the radial air dynamic pressure bearing portion 22 moves to the thrust air dynamic pressure bearing portion 23. It is configured to be sent. Also,
An air passage 30 and an air discharge passage 32 in the fixed shaft 13 are provided between the thrust air dynamic pressure bearing portion 23 and the motor driving portion.
, An air circulation return path is formed, and the air purified by the filter 33 is discharged to the drive space D via the motor drive unit through the air circulation return path.

On the other hand, at the center of the bottom surface of the thrust plate 27, a static elimination pin 35 is erected downward in the drawing so as to protrude into the air passage 30 of the fixed shaft 13 described above. The tip of the static elimination pin 35 of the thrust plate 27 is electrically connected to the fixed shaft 13 via a magnetic fluid seal 36.

That is, the magnetic fluid seal 36 is attached to the inner wall of the upper end portion inside the air passage 30 of the fixed shaft 13, and a pair of pole pieces 36b, 36b are formed on both end surfaces of the annular permanent magnet 36a in a substantially parallel manner. The conductive magnetic fluids 36c, 36c are attached and held on the inner peripheral edges of the pair of pole pieces 36b, 36b.
Is adsorbed to the tip of the static elimination pin 35 on the thrust plate 27 side.

By the magnetic fluid seal 36, the fixed shaft 13 made of a conductive material and the hub body 21 as a bearing member made of the conductive material are electrically connected. By grounding, the hub body 21 and the disk held by the hub body 21 are grounded.

According to the apparatus according to the present embodiment, the dust in the air discharged from the radial air dynamic pressure bearing portion 22 through the thrust air dynamic pressure bearing portion 23 is collected in the air discharge passage 32. Filter 33 as dust means
So that air contaminated by abrasion powder or the like generated in the dynamic pressure bearing portion is not discharged to the cleaned motor drive section and the drive space, and only the purified air is removed from the motor. Drive space D via drive unit
Is discharged into 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 the clean air in the motor drive unit or the drive space D is sent to the radial air dynamic pressure bearing portion 22, the radial air dynamic pressure bearing portion 22
The occurrence of seizure of the bearing portion can be prevented without providing dust collecting means in the air inflow portion.

Further, according to this embodiment, the rotating hub 21 holding the disk is always kept in the grounded state via the magnetic fluid seal 36 using a conductive magnetic fluid. Elimination of the generated charge is performed well even during rotation, and electrical protection of the head is performed.

Next, in the embodiment shown in FIG.
A static elimination pin 45 is provided so as to protrude upward from the upper end surface side of the fixed shaft 13 in the drawing. The conductive magnetic fluid 46c is adsorbed. The static elimination pin 45 is disposed along the center axis of the fixed shaft 13, and a communication path 40 to the air passage 30 forming an air circulation path is provided on a side portion of the fixed shaft 13.
Is arranged. In such an embodiment, the same static elimination action as in the above embodiment can be obtained.

In the embodiment shown in FIG.
As in the embodiment shown in FIG. 2, the static elimination pin 55 is provided so as to protrude upward from the center of the upper end surface of the fixed shaft 13 in the drawing, and the thrust elimination pin 55 on the fixed shaft 13 side The conductive magnetic fluid 56c of the magnetic fluid seal 56 attached to the plate 27 side is adsorbed. Then, it penetrates through the inside of the static elimination pin 55,
A communication passage 50 to the air passage 30 forming a circulation path of the pressurized air is arranged. In such an embodiment, the same static elimination action as in the above embodiment can be obtained.

Next, the embodiment shown in FIG. 4 is an embodiment in which the present invention is applied to a so-called fixed-end type HDD spindle motor, and has the same configuration as that shown in FIG. The same reference numerals are given to the members, and description thereof will be omitted, and portions having different configurations will be described.

In the HDD spindle motor shown in FIG. 4, the upper and lower ends of the fixed shaft 63 are screwed and fixed to the substantially closed drive case C, and are 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, the minute gap in the lower radial air dynamic pressure bearing 62 is
Is disposed so as to open above the outer portion of the motor, and through the gap between the stator set 1 and the rotor set 2, the clean air in the motor drive unit or the drive space D passes through the minute gap of the radial air dynamic pressure bearing 62. It is configured to be sent to.

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 an opening on the upper end side of the hub body 21 in the figure, 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 66.

That is, the magnetic fluid seal 66 is mounted on the upper surface of the thrust plate 67, and a pair of pole pieces are mounted on both end faces of the annular permanent magnet in a substantially parallel manner. The conductive magnetic fluid 66c 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 66 electrically connects the fixed shaft 63 and the hub body 21 as a bearing-side member, and the fixed shaft 63 is grounded. Is configured to be grounded.

A seal plate 69 is provided so as to cover the magnetic fluid seal 66 from the outside (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 in 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 increased, so that the hub body 21 is rotatably supported in the thrust direction while floating in the axial direction. It is configured to be.

At this time, the air pressure increasing means in the thrust air dynamic pressure bearing portion 61 may be a dynamic pressure generating groove similar to the radial air bearing portion 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 raising 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.

The flow of air in the thrust air dynamic pressure bearing portion 61 goes 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. The air is discharged from the opening 70a at the lower end in the drawing to the space inside the stator 14 in the radial direction through the air discharge passage 70, and communicates with the motor drive unit through the gap between the stator set 1 and the rotor set 2.

At this time, a filter 7 as dust collecting means is provided at the lower end opening 70a of the air discharge passage 70 in the figure.
3 is disposed, dust in the air that has passed through the air discharge passage 70 is captured by the filter 73,
The purified air is discharged into the drive space D via the motor drive unit.

As described above, also in the present embodiment, the air circulation outward path is provided so as to connect the radial air dynamic pressure bearing 62 and the thrust air dynamic pressure bearing 61 from the drive space D through the motor drive unit. After the clean air in the drive space D and the motor drive unit is sucked into the radial air dynamic pressure bearing unit 62, it is sent to the thrust air dynamic pressure bearing unit 61, and the thrust air dynamic pressure bearing unit 61 and the motor drive unit Between the air discharge passage 70
Is formed through the air circulation return path, and the air cleaned by the filter 73 is discharged to the drive space D through the motor drive unit through the air circulation return path.

In the apparatus according to the present embodiment as described above, the dust in the air discharged from the radial air dynamic pressure bearing 62 through the thrust air dynamic pressure bearing 61 is also collected by the dust collecting means provided in the air discharge path. As a result, air contaminated by abrasion powder or the like generated in the dynamic pressure bearing portion is prevented from being discharged to the cleaned motor drive portion and the drive space. Only the exhausted air is discharged into the drive space via the motor drive unit, and the drive space D is always kept clean, so that the rotational drive is performed without causing contamination of the disk or the like. I have.

At this time, since the clean air in the drive space D is fed into the radial air dynamic pressure bearing portion through the motor drive portion, dust collecting means is provided at the air inflow portion of the radial air dynamic pressure bearing portion 62. Even without this, it is possible to prevent the occurrence of seizure of the bearing portion.

According to the present embodiment, the rotating hub 21 holding the disk is always kept in the ground state via the magnetic fluid seal 69 using a conductive magnetic fluid. Elimination of the generated charge is performed well even during rotation, and head protection is performed.

In the embodiment shown in FIG. 4, a seal projection 67a close to the outer periphery of the fixed shaft 13 is formed integrally with the inner peripheral portion of the hole of the thrust plate 67. A so-called labyrinth seal is provided on the inner peripheral portion to protect the magnetic fluid seal 69. Such a labyrinth seal projection 67a is provided.
Need not necessarily be provided.

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 kinds 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.

[0071]

As described above, the first aspect of the present invention provides a gas circulation system in which a hydrodynamic gas flows from one side of a radial gas dynamic pressure bearing portion to the other side of a thrust gas dynamic pressure bearing portion. By providing a path and arranging the dust collecting means in the middle of the gas circulation path, dust in the gas discharged from the gas dynamic pressure bearing portion is captured by the dust collecting means, and air contaminated by wear powder and the like is removed. A gas-type dynamic pressure bearing device that can be maintained in a clean state with a simple configuration and prevents contamination of disks and the like, because it is configured not to discharge into a clean drive space. Reliability 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, when the gas passage provided inside the fixed shaft is provided so as to constitute a part of the gas circulation passage, the gas circulation passage is formed compact. Therefore, the effects of the above-described invention can be further improved.

Furthermore, the fixed shaft and the bearing-side member are electrically connected by a magnetic fluid seal using a conductive magnetic fluid to bring the bearing-side member into a ground state. For example, 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, so that the reliability of the apparatus can be further improved.

This effect is achieved by the gas type dynamic pressure bearing device according to claim 5, wherein the bearing side member is a disk hub, and the gas type dynamic pressure bearing device according to claim 6, wherein the device is arranged in a drive space containing clean gas. In a pressure bearing device, it is particularly preferably obtained.

Further, when the apparatus is arranged in the drive space having the clean gas, for example, if the dynamic pressure gas is circulated through the gas circulation forward path and the gas circulation return path as in the apparatus according to the seventh aspect, the gas can be reduced. Circulating is performed favorably, and the above-described effect can be greatly improved.

[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 an enlarged view of a static elimination mechanism according to another embodiment of the present invention.

FIG. 3 is an explanatory cross-sectional view showing, on an enlarged scale, a static elimination mechanism according to still another embodiment of the present invention.

FIG. 4 is a cross-sectional explanatory view showing a structure of an HDD spindle motor having a gas dynamic pressure bearing device according to 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 Air passage 32, 70 Air exhaust passage 33, 73 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 (7)

[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. In the gas-type dynamic pressure bearing device, the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion are configured such that the gas moves from one side to the other side, and the moving gas is A gas circulating passage circulating between the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion; and a dust collecting means disposed in the gas circulating 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 gas type according to claim 1, wherein the gas circulation return path according to claim 1 includes a gas passage provided inside the fixed shaft, and dust collecting means provided in the gas passage inside the fixed shaft. Dynamic pressure bearing device. 4. A magnetic fluid seal using a conductive magnetic fluid is provided between the fixed shaft according to claim 1 and a bearing-side member, and the fixed shaft and the bearing-side member are electrically connected by the magnetic fluid seal. A gas-type dynamic pressure bearing device, wherein the bearing-side member is connected to ground via the magnetic fluid seal and a fixed shaft. 5. The 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. 6. A gas-type 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. 7. A gas circulation forward path which sucks clean gas in the drive space according to claim 6 into a radial gas dynamic pressure bearing and sends it to a thrust gas dynamic pressure bearing, and drives the gas in the thrust gas dynamic pressure bearing into the drive. A gas type dynamic pressure bearing device, wherein a gas circulation path is constituted by a gas circulation return path discharged to the space side.