JPH1193948A - Gas thrust bearing, gas radial bearing, spindle motor, and rotator device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotator device reduced in an adhesion area between a bearing fixed member and a bearing moving member during starting and the starting load torque and the number of enduring times for the number of starting and stopping times. SOLUTION: A dynamic pressure creating groove 3 is formed in the opposite surface of one of a thrust bearing fixing member 1 and a thrust bearing moving member 2. Fine protrusions 4 are formed while kept away from the dynamic pressure creating groove 3. The fine protrusion 4 ensures a gap smaller than a gap during the creation of dynamic pressure during a stop. When the fine protrusion 4 is situated, the thrust bearing fixing member 1 and the thrust bearing moving member 2 are not adhered to each other throughout a whole surface during a stop of rotation and a parallel distance is held by a gap smaller than a gap during the creation of dynamic pressure. Thereby, the adhering area during starting is remarkably decreased and load torque during starting is eminently reduced, the number of enduring times for the number of starting and stopping times is remarkably increased, and the bearings are well suitable for the bearings of a polygon mirror, an HDD, and a spindle motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas thrust bearing and a gas radial bearing in which the contact area between the bearing fixing member and the bearing movable member at the time of starting is small, the starting load torque is small, and the number of times of starting and stopping is large. And a spindle motor and a rotating body device.

[0002]

2. Description of the Related Art A gas thrust bearing and a gas radial bearing employed in a conventional spindle motor have a structure in which a dynamic pressure generating groove is formed on one of opposing surfaces of a bearing fixing member and a bearing movable member. .

[0003]

In the above-mentioned conventional spindle motor, the bearing fixing member and the bearing movable member of the gas thrust bearing are in close contact with each other at the time of start-up when the motor axis is vertical. In addition, in the use condition in which the motor axis is horizontal, the bearing fixing member and the bearing movable member of the gas radial bearing are in close contact at the time of startup. In both cases, there is a problem that the starting load torque is large and the facing surfaces of the bearing fixing member and the bearing movable member are worn, so that the number of times of starting and stopping is small.

The present invention relates to a gas thrust bearing, a gas radial bearing, and a spindle motor in which the contact area between the bearing fixing member and the bearing movable member at the time of starting is small, the starting load torque is small, and the number of times of starting and stopping is large. , And a rotator device.

[0005]

The first invention of the present application comprises a ring-shaped thrust bearing fixing member and a ring-shaped thrust bearing movable member, and a dynamic pressure generating groove is formed on one of the opposing surfaces. In the engraved gas thrust bearing, a small projection that holds the gap between the thrust bearing fixed member and the thrust bearing movable member in parallel with a dimension smaller than the gap when the dynamic pressure is generated between the thrust bearing fixed member and the thrust bearing movable member is provided. ,
It is an object of the present invention to provide a gas thrust bearing characterized in that a dynamic pressure generating groove is provided on a facing surface of a thrust bearing fixing member or a thrust bearing movable member in which the dynamic pressure generating groove is engraved, avoiding the dynamic pressure generating groove.

A second invention of the present application is a gas comprising a ring-shaped thrust bearing fixing member and a ring-shaped thrust bearing movable member, wherein a dynamic pressure generating groove is engraved on one of the opposing surfaces. In the thrust bearing, a small projection that keeps the gap between the thrust bearing fixed member and the thrust bearing movable member parallel with a dimension smaller than the gap when the dynamic pressure is generated between the thrust bearing fixed member and the thrust bearing movable member is formed in the dynamic pressure generating groove. The present invention provides a gas thrust bearing characterized in that the gas thrust bearing is provided on an inner peripheral portion with respect to a facing surface of a thrust bearing fixing member or a thrust bearing movable member on which is engraved.

The third invention of the present application is directed to a gas radial bearing comprising a cylindrical radial bearing fixing member and a cylindrical radial bearing movable member, wherein a dynamic pressure generating groove is engraved on one of the opposing surfaces. The distance between the radial bearing fixed member and the radial bearing movable member is smaller than the gap at the time when dynamic pressure is generated between the radial bearing fixed member and the radial bearing movable member at both axial ends of the opposed surface of the radial bearing fixed member or the radial bearing movable member. Is provided on the circumference of the bearing, to provide a gas radial bearing.

A fourth invention of the present application is to provide a spindle motor characterized in that a bearing is constituted by the gas thrust bearing and the gas radial bearing of the present invention. A fifth invention of the present application is to provide a rotating device in which a rotating medium such as a storage medium such as a magnetic disk or an optical disk or a polygon mirror is attached to a spindle of a spindle motor.

[0009]

FIG. 1 shows a gas thrust bearing according to a first embodiment of the present invention. This gas thrust bearing comprises a thrust bearing fixing member 1 and a thrust bearing movable member 2 as shown in FIG. 1 (a), and as shown in FIG. The dynamic pressure generating grooves 3 are engraved in a uniform arrangement in the circumferential direction, and three minute projections 4 are provided at different positions 120 ° apart from the dynamic pressure generating grooves 3.
Is provided.

The thrust bearing fixing member 1 and the annular plate-shaped thrust bearing movable member 2 are both formed in an annular plate shape from ceramics or other highly wear-resistant materials. The small projections 4 have a size (about 1/2 to 1) smaller than a gap (generally 1 to 10 μm depending on the size of the bearing, but generally 1 to 10 μm) when the dynamic pressure is generated between the thrust bearing fixing member 1 and the thrust bearing movable member 2. The gap between the thrust bearing fixing member 1 and the thrust bearing movable member 2 is maintained in parallel by providing three at different positions by 120 °.

The fine projections 4 of this embodiment are in the form of short pins made of a lubricating and abrasion-resistant substance such as diamond-like carbon, silicon nitride or silicon carbide. Alternatively, a hole is formed in the opposed surface of the movable member 2 of the thrust bearing, and the hole is fitted and fixed.
Note that the minute projections 4 may be formed by sputtering or CVD.

As described above, when the minute projections 4 are provided, the thrust bearing fixing member 1 and the thrust bearing movable member 2 are not in close contact with each other when the rotation is stopped, and are parallel to each other at a gap smaller than the gap when the dynamic pressure is generated. Since the contact area is maintained, the contact area at the time of startup is significantly reduced, and the startup load torque is greatly reduced. Therefore, it is suitable as a bearing for a polygon mirror or a spindle motor of an HDD.

The microprojections 4 are not limited to those shown in FIG. 1B, but may be those shown in FIGS. 2A, 2B and 2C. The microprojection 4 shown in FIG. 2 (b) is a ring-shaped member made of a material containing aluminum as a base material and containing particles harder than the base material such as silicon particles and silicon dioxide particles. Particles harder than the base material such as silicon particles or silicon dioxide particles are opposed by shrink-fitting the inner peripheral surface of the bearing movable member 2 and then polishing the opposing surface of the thrust bearing fixing member 1 or the thrust bearing movable member 2. It protrudes innumerably from the surface. Further, the minute projections 4 may be made of a material having a low friction coefficient and wear resistance, such as DLC or TiN.

The fine projections 4 shown in FIG. 2 (a) are made of a material having lubricity such as diamond-like carbon, silicon nitride or silicon carbide formed by sputtering or CVD, facing the thrust bearing fixing member 1 or the thrust bearing movable member 2. It is formed at a position different from the inner circumferential portion by 120 °. FIG.
The microprojections 4 shown in FIG. 3C are formed so that the surface of the inner peripheral portion of the opposing surface of the thrust bearing fixing member 1 or the thrust bearing movable member 2 is roughened.

2 (a), 2 (b) and 2 (c), since the minute projections 4 are provided on the inner peripheral portion of the opposed surface of the thrust bearing fixing member 1 or the thrust bearing movable member 2, the starting load torque is reduced. As shown in FIG. 1 (b), the size is even smaller than when the minute projections 4 are provided on the outer peripheral portion. 2 (a), 2 (b) and 2 (c), minute projections 4 are provided on the opposing surface of the thrust bearing fixing member 1 or the thrust bearing movable member 2 in which the dynamic pressure generating grooves 3 are provided. However, if the minute projections 4 are limited to being provided on the inner peripheral portion of the opposing surface, even if they are provided on the opposing surface of the thrust bearing fixing member 1 or the thrust bearing movable member 2 on which the dynamic pressure generating groove 3 is not provided. It is good because it does not interfere with the pressure generating groove 3.

FIG. 3 shows an embodiment of a gas radial bearing according to the third invention of the present application. This gas radial bearing has two cylindrical shapes, large and small, which are fitted with a dynamic pressure generation gap on the inside and outside. The smaller one is, for example, the radial bearing fixing member 5 and the larger one is the radial bearing movable member 6. hand,
The dynamic pressure generating groove 7 is engraved on one of the opposing surfaces in the circumferential direction at equal intervals, and the radial bearing fixing member 5 or the radial bearing movable member 6 is opposed regardless of whether the dynamic pressure generating groove 7 is provided. At both ends of the surface, endless microprojections 8, 8 which are smaller than the gap when the dynamic pressure is generated and project into the gap space are provided.

As described above, the endless minute projections 8, 8
When the HDD is installed so that the axis of the spindle motor is horizontal, the inner peripheral surface of the radial bearing movable member 6 does not linearly adhere to the outer peripheral surface of the radial bearing fixing member 5 when the HDD is stopped. That is, a state in which two cylindrical surfaces having different diameters do not inscribe with each other does not occur, and the endless minute projections 8, 8 make the inner peripheral surface of the radial bearing movable member 6 move the outer peripheral surface of the radial bearing fixing member 5 when the dynamic pressure is generated. Keep two smaller gaps. Therefore, the contact area at the time of startup is significantly reduced, the startup load torque is greatly reduced, the durability of the number of startups / stops is greatly increased, and it is suitable as a spindle motor bearing of an HDD which can be freely placed. is there.

FIG. 4 shows an embodiment of a gas dynamic pressure bearing in which a gas thrust bearing according to the first and second aspects of the present invention and a gas radial bearing according to the third aspect are combined. In this gas dynamic pressure bearing, one of the movable bearing member and the movable bearing member is three bearing members 9, 10, and 11, and the other of the movable bearing member or the movable movable member is the remaining one bearing member 12. is there. The bearing members 9 and 11 are annular plates, and the bearing members 10 and 12 are cylindrical. In addition, the bearing member 10,
11 may be formed integrally.

In this gas dynamic pressure bearing, a thrust dynamic pressure generating groove is formed in the upper and lower end surfaces of the bearing member 12 or the bearing members 9 and 11, and the gas dynamic pressure bearing is also provided in FIGS. 1 (b), 2 (a), 2 (b), and 2 (c). (C)
Are formed, and a radial dynamic pressure generating groove is formed in one of the bearing members 10 and 12, and endless minute projections 8, 8 shown in FIG. 3B are formed. It is assumed that

Therefore, regardless of whether the shaft center of the spindle motor employing the gas dynamic pressure bearing is vertical or horizontal, the contact area at the time of startup is significantly reduced, and the startup load torque is greatly reduced. The durability of the number of times of starting / stopping is greatly increased, which is suitable as a bearing for a spindle motor of a polygon mirror, and also suitable as a bearing for a spindle motor of an HDD which can be freely placed.

FIG. 5 shows a first embodiment of the spindle motor according to the fourth invention of the present application. This spindle motor SM
₁ is a substantially cylindrical spindle support member 13A having a flange portion 13a at a lower end, and a spindle 14A formed into a substantially cap shape having a flange portion 14a at a lower end and a closed upper surface is covered by a spindle support member 13A. A rotation shaft 15 provided from the center of the upper surface portion 14b of the upper surface portion 14A hangs inside the spindle support member 13A. Further, a stator 16A is fitted to a lower portion of the inner surface of the spindle support member 13A, and is inserted into a slot of the stator 16A. While a motor coil 17A is provided, a motor permanent magnet 18A is provided at the lower end of the rotating shaft 15 so as to correspond to the magnetic pole teeth of the stator 16A, and thus a motor unit is provided. Are supported by a spindle support member 13A via a gas radial bearing shown in FIG. The flange portion 14a of 4A is supported by the flange portion 13a of the spindle support member 13A via the gas thrust bearing shown in FIG. 1 or FIG. The lower portion of the inner surface of the spindle support member 13A is closed by a cover plate 19.

FIG. 6 shows a second embodiment of the spindle motor according to the fourth invention of the present application. This spindle motor SM
₂ , a substantially disk-shaped spindle support member 13B is covered with a substantially cap-shaped spindle 14B, and a fixed shaft 20 provided from the center of the spindle support member 13B passes through the inside of the spindle 14B. The stator 1 is provided on the upper part of the inner surface of the spindle support member 13B.
6B is fitted and a motor coil 17B is provided in a slot of the stator 16B, while a permanent magnet 18B for motor is provided on the spindle 14B so as to correspond to the magnetic pole teeth of the stator 16B, and a motor section is provided. Further, the spindle 14B is supported by the fixed shaft 20 via a gas radial bearing shown in FIG. 3, and the flange 14a of the spindle 14B is supported by a spindle thrust bearing via a gas thrust bearing shown in FIG. 1 or FIG. Member 13
B is supported.

The spindle motor SM ₁ shown in FIG. 5 and the spindle motor SM ₂ shown in FIG.
Or 14B is supported by the spindle support member 13A or 13B via the gas radial bearing shown in FIG. 3 and the gas thrust bearing shown in FIG. 1 or FIG. The torque is greatly reduced, and the contact area at startup is dramatically reduced, regardless of whether the spindle motor shaft is vertical or horizontal, the startup load torque is greatly reduced, and the endurance of the number of starts and stops Is greatly increased, and is suitable as a bearing for a spindle motor of a polygon mirror, and also suitable as a bearing for a spindle motor of an HDD which can be freely placed.

FIG. 7 shows a third embodiment of the spindle motor according to the fourth invention of the present application. This spindle motor SM
₃ , a substantially disk-shaped spindle support member 13C is covered with a substantially cap-shaped spindle 14C having a flange portion 14a, and a fixed shaft 20 provided from the center of the spindle support member 13C is provided inside the spindle 14C. The gas dynamic pressure bearing shown in FIG. 4 is provided inside the spindle 14C, the spindle 14C is supported on the fixed shaft 20 via the gas dynamic pressure bearing, and the spindle support member 13C is provided with a motor coil 17C. On the other hand, a permanent magnet 18C for a motor is provided on the lower surface of the flange 14a of the spindle 14C, and thus a motor is provided. The upper inside of the spindle 14C is closed by a cover plate 19.

FIG. 8 shows a fourth embodiment of the spindle motor according to the fourth invention of the present application. This spindle motor SM
Reference numeral ₄ denotes a substantially cylindrical spindle support member 13D having a flange portion 13a covered by a substantially cap-shaped spindle 14D having a flange portion 14a.
A rotary shaft 15 provided from the center of the upper surface of the 4D passes through the inside of the spindle 14D, and the gas dynamic pressure bearing shown in FIG. 4 is provided inside the spindle 14D, whereby the spindle 14D is connected via the gas dynamic pressure bearing. Supported by the spindle support member 13D.
The motor coil 17D is provided on the flange portion 13a of the motor, while the permanent magnet 18D for motor is provided on the lower surface of the flange portion 14a of the spindle 14D, and thus the motor portion is provided. Cover plate 19
Is closed by.

The spindle motor SM ₃ shown in FIG. 7 and the spindle motor SM ₄ shown in FIG.
Alternatively, since 14D is supported by the spindle support member 13C or 13D via the gas dynamic pressure bearing shown in FIG. 4, the contact area at the time of startup is significantly reduced, the startup load torque is greatly reduced, and the spindle motor The axis is vertical,
Regardless of the horizontal position, the contact area at startup is dramatically reduced, the startup load torque is greatly reduced, and the endurance of start / stop times is dramatically increased. It is suitable as a bearing for a spindle motor of an HDD which can be freely placed.

FIG. 9 shows a case where the spindle motor of FIG. 7 is employed.
2 shows a rotating body device. This rotator device is the spin device shown in FIG.
Dollar motor SM_ThreePolygon mirror on spindle 14C
21 is attached and the mirror case 22 is a spindle motor
SM_ThreeSupported by the spindle support member 13C.
It is good. FIG. 10 shows the spindle motor SM of FIG.₁Ma
Or the spindle motor SM shown in FIG. _TwoRotating body equipment adopting
Position. This rotator device is a disk device,
Spindle motor SM of the first invention₁Or SM_Twoof
Turn the spindle, such as a magnetic disk or optical disk,
A plurality of rolling disks 23 are attached.

Since the rotating body device shown in FIGS. 9 and 10 employs the spindle motor provided with the gas dynamic pressure bearing of the present invention, the contact area at the time of startup is significantly reduced, and the startup load torque is greatly increased. , Regardless of whether the spindle motor shaft is vertical or horizontal, the contact area at startup is dramatically reduced, the startup load torque is greatly reduced, and the number of endurance times of start and stop is dramatically increased It is suitable as a spindle motor bearing for polygon mirrors,
Alternatively, it is suitable as a bearing for a spindle motor of an HDD which can be freely placed.

[0029]

As described above, the gas thrust bearing, the gas radial bearing, the spindle motor, and the rotating body device of the present invention all have a small contact area between the bearing fixing member and the bearing movable member at the time of starting. The starting load torque is small, the endurance number of start / stop times is large, and the initial purpose can be achieved.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a gas thrust bearing according to the first invention of the present application, in which (a) is a central longitudinal sectional view and (b).
FIG. 4 is a front view of one of the opposing surfaces of the thrust bearing fixing member and the thrust bearing movable member.

FIG. 2 is a front view of one of opposing surfaces of a thrust bearing fixing member and a thrust bearing movable member, showing another embodiment of a gas thrust bearing common to the first and second inventions of the present application.

FIGS. 3A and 3B show an embodiment of a gas radial bearing according to the third invention of the present application, in which FIG. 3A is a longitudinal sectional view at the center, and FIG. 3B is an overall front view of the right half of an inner bearing member.

FIG. 4 is a longitudinal sectional view showing an embodiment of a gas dynamic pressure bearing in which the gas thrust bearing of the first and second inventions of the present application and the gas radial bearing of the third invention are combined.

FIG. 5 is a longitudinal sectional view showing a first embodiment of a spindle motor according to a fourth invention of the present application.

FIG. 6 is a longitudinal sectional view showing a second embodiment of the spindle motor according to the fourth invention of the present application.

FIG. 7 is a longitudinal sectional view showing a third embodiment of the spindle motor according to the fourth invention of the present application.

FIG. 8 is a longitudinal sectional view showing a fourth embodiment of the spindle motor according to the fourth invention of the present application.

FIG. 9 is a sectional view of a polygon mirror rotating device as a rotating device employing the spindle motor of the fourth invention of the present application.

FIG. 10 is a perspective view of an HDD as a rotating device employing the spindle motor according to the fourth invention of the present application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Thrust bearing fixing member 2 Thrust bearing movable member 3 Dynamic pressure generating groove 4 Micro projection 5 Radial bearing fixing member 6 Radial bearing movable member 7 Dynamic pressure generating groove 8 Endless micro projection 9,10,11,12 Gas dynamic pressure bearing bearing member SM _{1 constituting, SM 2, SM 3, SM} 4 spindle motor 13A, 13B, 13C, 13D spindle support member 14A, 14B, 14C, 14D spindle 17A, 17B, 17C, 17D motor coils 18A, 18B, 18C, 18D Permanent magnet for motor 21 Polygon mirror 23 Rotated disk

Claims (5)

[Claims] 1. A gas thrust bearing comprising a ring-shaped plate-shaped thrust bearing fixing member and a ring-shaped plate-shaped thrust bearing movable member, wherein a dynamic pressure generating groove is engraved on one of the opposing surfaces. The dynamic pressure generating groove is formed with a minute projection for maintaining the gap between the thrust bearing fixing member and the thrust bearing movable member in parallel with a dimension smaller than the gap when the dynamic pressure is generated between the bearing fixing member and the thrust bearing movable member. A gas thrust bearing comprising a thrust bearing fixing member or a thrust bearing movable member facing a surface avoiding a dynamic pressure generating groove. 2. A gas thrust bearing comprising a ring-shaped thrust bearing fixing member and a ring-shaped thrust bearing movable member, wherein a dynamic pressure generating groove is formed on one of the opposing surfaces. The dynamic pressure generating groove is formed with a minute projection for maintaining the gap between the thrust bearing fixing member and the thrust bearing movable member in parallel with a dimension smaller than the gap when the dynamic pressure is generated between the bearing fixing member and the thrust bearing movable member. A gas thrust bearing, wherein the gas thrust bearing is provided on an inner peripheral portion with respect to a surface of the thrust bearing fixing member or the thrust bearing movable member. 3. A gas radial bearing comprising a cylindrical radial bearing fixing member and a cylindrical radial bearing movable member, wherein a dynamic pressure generating groove is engraved on one of the opposing surfaces. An endless endless member that keeps the distance between the radial bearing fixed member and the radial bearing movable member parallel to each other at both axial ends of the opposed surface of the radial bearing movable member with a dimension smaller than the gap when the dynamic pressure is generated between the radial bearing fixed member and the radial bearing movable member. A gas radial bearing, wherein fine projections are provided on the circumference of the bearing. 4. A spindle motor comprising a gas thrust bearing according to claim 1 or claim 2 or a gas radial bearing according to claim 3. 5. A rotating device according to claim 4, wherein a rotating body such as a storage medium such as a magnetic disk or an optical disk or a polygon mirror is mounted on a spindle of the spindle motor.