JPH1169713A - Spindle motor, and rotating body equipment using the spindle motor as drive source for rotating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a normal/reverse rotation spindle motor and a rotating body equipment, using the spindle motor as a drive source for the rotating body. SOLUTION: A radial dynamic pressure bearing portion of the dynamic pressure bearing of a spindle motor is constituted with a cylindrical bearing member 3, having a flat inner peripheral surface and a columnar bearing member 2, having regular ups and downs on the outer peripheral surface. Then, the columnar bearing member 2 is made by using three or more flat circular column pieces 2a to 2c, having a same shape and size with deviated center shaft holes provided at the same position and a shaft 1 having a concentric hole, a plurality of circular column pieces 2a to 2c are laminated orderly by arranging shaft holes with deviated centers, by changing the directions at constant angles of 180 deg. and 120 deg., the concentric shaft is pressed in the shaft holes with the deviated centers, and then the laminated type circular columnar bearing member with ups and downs constituted regularly on the outer peripheral surface can be constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor provided with an air dynamic pressure bearing capable of rotating in one direction or forward and reverse,
The present invention also relates to a rotator device for rotating a rotator such as a magnetic disk, an optical disk, or a polygon mirror in either a forward direction or a reverse direction.

[0002]

2. Description of the Related Art A spindle motor such as a coreless servomotor is used as a drive source for a rotating device such as a magnetic disk device, an optical disk device, or an optical deflector having a polygon mirror. Since the spindle motor used in such a rotating body device is a small high-speed rotating machine, an air dynamic pressure bearing having features such as little change in bearing characteristics and extremely low noise is widely used.

There are a radial bearing and a thrust bearing as air dynamic pressure bearings. The structure of a conventional radial bearing particularly related to the present invention will be outlined with reference to FIG. Is a cylindrical bearing member, and 7 is a cylindrical bearing member having a flat inner peripheral surface. The dynamic pressure generating groove G may be formed on the inner peripheral surface of the cylindrical bearing member 7, but in this case, the outer peripheral surface of the cylindrical bearing member 6 is a flat surface. The dynamic pressure generating groove G is, for example, a herringbone groove. In addition, although the cylindrical bearing member 6 is formed integrally with the shaft, these may be formed separately and combined. When manufactured separately, the cylindrical bearing member 6 is provided with a shaft hole along the central axis, and the shaft is press-fitted into the shaft hole.

As described above, the radial dynamic pressure bearing is composed of the cylindrical bearing member 6 and the cylindrical bearing 7, and the cylindrical bearing member 6
One of the outer peripheral surface and the inner peripheral surface of the cylindrical bearing member 7 is a surface having a dynamic pressure generating groove, and the other surface is a flat surface having no dynamic pressure generating groove. Then, a positive pressure is generated by pushing working air by high-speed rotation into a bearing clearance of several microns formed between the surface having the dynamic pressure generating groove and the flat surface not having the dynamic pressure generating groove,
It functions as a pump-in type radial dynamic pressure bearing.

A radial dynamic pressure bearing as shown in FIG. 7 is a mechanism for generating dynamic pressure by converting rotational energy into pressure through frictional force by providing a shallow groove at an acute angle to the rotational direction. It can only rotate in one direction. That is, whether the bearing is the radial dynamic pressure bearing for the forward direction or the radial dynamic pressure bearing for the reverse direction is determined at the time of manufacturing. Recently, for example, Transactions of the Japan Society of Mechanical Engineers 5
No. 8, No. 555, a paper entitled “Forward and Reverse Rotating Herringbone Journal Gas Bearing Using Pump-in Type and Pump-out Type” (Paper No. 92-0550) was published.

FIG. 8 is a perspective view of a partial cross section showing the principle of the forward / reverse rotating radial dynamic pressure bearing disclosed in the above-mentioned paper. Reference numeral 6 denotes a herringbone dynamic pressure having a plurality of substantially V-shaped shallow grooves on the outer peripheral surface. A cylindrical bearing member in which the generating groove G is formed, 7 is a cylindrical bearing member rotatably supporting the cylindrical bearing member 6, and 8 is a communication hole to the outside air provided on a wall surface of the cylindrical bearing member 7. It is. The conduction hole 8 is a herringbone dynamic pressure generating groove G.
It is arranged so that it may be located in the center of. In addition, a plurality of, for example, three conductive holes 8 are provided at equal angular intervals. This forward / reverse rotating radial dynamic pressure bearing uses a pump-in system that pushes lubricating gas into the bearing depending on the direction of rotation to increase the pressure inside the bearing. By switching the pump-out system that generates a high pressure by the resistance of the above, it functions as a bearing.

To switch between the pump-in system and the pump-out system, a forward / reverse switching valve (not shown) is connected to a communication hole 8 with the outside air.
This is realized by providing That is, in the case of forward rotation, the forward / reverse switching valve is closed to shut off the communication hole 8 to the outside air, and the pump functions as a pump-in type bearing for generating a positive pressure by pushing the working gas into the bearing clearance by the pump-in effect. In the case of reverse rotation, the valve is opened to open the communication hole 8 to the outside air, and the working gas is sucked into the bearing clearance through the communication hole 8 by the pump-out effect to generate a flow toward the shaft end, thereby causing a positive flow. It functions as a pump-out type bearing that generates pressure. However, as for the forward / reverse rotation dynamic pressure bearing, there is no thing suitable for the switching means of the pump-in system and the pump-out system, which has been developed.
It has not been put to practical use yet.

Incidentally, in both the one-way rotating radial dynamic pressure bearing and the forward / reverse rotating radial dynamic pressure bearing, a dynamic pressure generating groove such as a herringbone groove must be formed on one of the bearing surfaces. The formation of the dynamic pressure generating groove is usually performed by NC processing on the outer peripheral surface of the cylindrical bearing member and by NC processing or plastic forming by ball rolling on the inner peripheral surface of the cylindrical bearing member. The bearing member is a soft metal such as a copper alloy or an aluminum alloy, but the surface to be processed is the outer peripheral surface of a cylinder or the inner peripheral surface of a cylinder, so advanced processing technology is required and mass production is difficult. . If a large number of NC machines are installed and processed by a large number of skilled workers, mass production is possible, but this greatly increases the manufacturing cost. Under such circumstances, there is no practical spindle motor having a dynamic pressure bearing and capable of rotating forward and reverse.
Therefore, a rotating body device that uses a spindle motor having a dynamic pressure bearing as a driving source of the rotating body and that can rotate normally and reversely has not yet been put to practical use.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle motor having a dynamic pressure bearing capable of rotating forward and backward, or to use this spindle motor as a drive source for a rotating body such as a magnetic disk, an optical disk or a polygon mirror. An object of the present invention is to provide a rotating body device. Another object of the present invention is to provide a spindle motor equipped with a radial dynamic pressure bearing capable of easy one-way rotation and forward / reverse rotation suitable for mass production and a rotating body device using the spindle motor as a driving source of a rotating body. Is to provide.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a spindle motor in which a rotor is supported on a stator by a dynamic pressure bearing, or a rotating body using the spindle motor capable of rotating in a forward or reverse direction as a driving source of the rotating body. In the apparatus, the dynamic pressure bearing is stacked by stacking three or more flat cylindrical pieces having the same shape and dimensions having an eccentric shaft hole with the eccentric shaft holes aligned and sequentially changing the direction at a certain angle, One concentric shaft was press-fitted and fixed in the eccentric shaft hole to form a laminated cylindrical bearing member having regular irregularities formed on the outer peripheral surface, and a cylindrical bearing member having a flat inner peripheral surface.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 3 and 4, which are sectional views cut in the direction of the central axis, the cylindrical bearing member having an outer peripheral surface having regular steps, ie, irregularities, is provided.
When inserted and arranged in a cylindrical bearing member having a flat inner peripheral surface, the bearing clearance formed between them is such that a plurality of eccentric donut-shaped voids of the same number as the cylindrical pieces change direction at a fixed angle. They are stacked. As shown exaggeratedly in FIG. 6, the eccentric donut-shaped gap has the same axial thickness as that of the cylindrical piece, and its outer peripheral surface is the inner peripheral surface of the cylindrical bearing member. Since the inner peripheral surface is the outer peripheral surface of the cylindrical piece, if the predetermined angle is 180 degrees, the thickness in the circumferential direction is the thinnest at the farthest part of the eccentric shaft hole of the cylindrical piece, The nearest part at the position of the degree is the thickest, and the thickness during this period changes gradually.
In short, the eccentric donut-shaped void is such that the farthest part of the eccentric shaft hole is the smallest, the closest part is the largest, and the part between them is gradually changing in size.

When the eccentric donut-shaped gap as shown in FIG. 6 is laminated, if the predetermined angle is set to 180 degrees, the second eccentric donut-shaped gap is placed above the maximum gap portion of the first eccentric donut-shaped gap. The minimum gap portion of the eccentric donut-shaped void is located, and the largest void portion of the third stage eccentric donut-shaped void is located above the minimum void portion of the second-stage eccentric donut-shaped void. Will be. Naturally, the largest gap portion of the second-stage eccentric donut-shaped gap is located above the smallest gap portion of the first-stage eccentric-shaped donut-shaped gap. The minimum gap portion of the third-stage eccentric donut-shaped gap is located above the largest gap portion of the gap.

Therefore, wide gaps and narrow gaps are alternately formed in the thrust direction and alternately form steps. Further, as described above, the width of the donut-shaped void, which is given by the width between the outer peripheral surface and the inner peripheral surface, changes gradually in the radial direction. In this way, a gap that generates a regular step in the thrust direction and changes gradually in the radial direction serves as a bearing clearance between the outer peripheral surface of the cylindrical bearing member and the inner peripheral surface of the cylindrical bearing member. As a result, when the cylindrical bearing member rotates at a high speed in the forward direction, a pressure difference is generated in the working air in both the thrust direction and the radial direction, thereby functioning as a dynamic pressure bearing. Also, when rotating in the opposite direction, there is no directivity in the bearing clearance, and in exactly the same way, a pressure difference occurs in the working air in both the thrust and radial directions,
Functions as a dynamic pressure bearing. Therefore, it functions not only as a one-way rotating dynamic pressure bearing but also as a forward / reverse rotating radial dynamic pressure bearing. In this case, there is no need to provide the dynamic pressure bearing with a forward / reverse rotation switching means such as a forward / reverse rotation switching valve.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a shaft rotating type spindle motor according to the present invention, which is rotatable forward and backward. 10 is a base plate of a stator, 11 is a stator coil, 12 is a rotor magnet, and 13 is a substantially cup of a rotor. The rotating hub such as a floppy disk or an optical disk is supported by the hub. The dynamic pressure bearing includes a concentric shaft 1 also serving as a shaft, and cylindrical pieces 2a, 2a, 2c having the same shape and dimensions having an eccentric hole into which the concentric shaft 1 is press-fitted and fixed.
b, 2c, a laminated cylindrical bearing member 2, a cylindrical bearing member 3 having a flat inner peripheral surface, a donut-shaped upper cover 4, and a donut-shaped lower cover 5.
The cylindrical bearing member 3 is erected on a base plate 10, and a substantially cup-shaped hub 13 is coaxially fixed to the upper end of the shaft 1. The stator coil 11 is attached to the outer peripheral surface of the cylindrical bearing member 3 and has a substantially cup-shaped hub 13.
The rotor magnet 12 is attached to the inner peripheral surface of the rotor.

In the spindle motor shown in FIG. 1, the radial dynamic pressure is applied to the bearing clearance between the outer peripheral surface having regular irregularities of the laminated cylindrical bearing member 2 and the flat inner peripheral surface of the cylindrical bearing member 3. Occur. In the spindle motor shown in FIG. 1, a magnetic bearing or a thrust bearing of a dynamic pressure bearing is used as necessary. For example, a laminated cylindrical bearing member 2
A dynamic pressure generating groove such as a spiral groove is formed on the upper end surface and the lower end surface of the donut-shaped upper cover 4 and the upper end surface of the donut-shaped lower cover 5 are flat. A dynamic pressure bearing can be configured.

FIG. 2 is a perspective view of an embodiment in which the rotating device according to the present invention is a floppy disk device. A plurality of floppy disks 14 are supported by a rotating member supporting portion of a spindle motor SM. And selectively driven to rotate in one direction or in both forward and reverse directions.

FIG. 3 is a longitudinal sectional view of a forward / reverse rotatable dynamic pressure bearing in which the eccentric relationship is exaggerated for explaining the configuration and operation of the forward / reverse rotatable spindle motor of FIG. . In FIG. 3, three cylindrical pieces 2a, 2b and 2c are components of the cylindrical bearing member 2. Each cylindrical piece 2a, 2
Reference numerals b and 2c denote cylindrical pieces having the same diameter and thickness, and having a flat surface having an eccentric shaft hole formed slightly eccentric from the central axis. These three flat-surfaced cylindrical pieces are shown in FIG.
As shown in the cross-sectional view, the eccentric shaft holes are aligned and stacked in order from the top at an angle of 180 degrees, and the concentric shaft 1 serving as a shaft is press-fitted and fixed to these eccentric shaft holes. .
Alternatively, the eccentric shaft holes may be aligned and stacked at different angles of 120 degrees from the top in order, and the concentric shaft 1 serving as a shaft may be press-fitted and fixed to these eccentric shaft holes. In this way, the laminated cylindrical bearing member 2 is configured to have a predetermined outer shape. The stacked cylindrical bearing member 2 is rotatably inserted into the cylindrical bearing member 3.

FIG. 4 shows cylindrical pieces 2a, 2a, 2a, 2a having flat surfaces of the same shape and dimensions each having an eccentric shaft hole.
b, 2c, 2d, and 2e are stacked with the eccentric shaft holes aligned and sequentially changing the direction at a fixed angle, and one concentric shaft 1 is press-fitted and fixed to the eccentric shaft holes to remove regular irregularities. 1 is a longitudinal sectional view of a hydrodynamic bearing capable of forward / reverse rotation composed of a laminated cylindrical bearing member 2 and a cylindrical bearing member 3 formed on the outer peripheral surface. FIG. is there. The constant angle in FIG. 4 is selected as in FIG.

FIG. 1 shows a rotary shaft type spindle motor, but a radial bearing portion composed of a laminated cylindrical bearing member and a cylindrical bearing member having a flat inner peripheral surface as shown in FIG. 3 or FIG. According to the present invention, a fixed shaft type spindle motor in which a rotor is supported by a stator with an air dynamic pressure bearing having the following structure can be used.

[0020]

According to the present invention, an air dynamic pressure bearing in a spindle motor according to the present invention or a rotating device using the spindle motor as a driving source of a rotating body has a plurality of cylindrical bearing members as radial dynamic pressure bearing components. Since it can be manufactured simply by changing the direction of the cylinder pieces at a fixed angle and assembling them, there is no need to form dynamic pressure generating grooves such as herringbone grooves by conventional laborious NC processing, etc. Therefore, it can be manufactured in large quantities and at low cost. Conventionally, since the dynamic pressure generating grooves are formed by NC processing or the like, both the columnar bearing member and the cylindrical bearing member need to have a certain diameter, and it is difficult to manufacture a small dynamic pressure bearing due to the restriction of the mechanical processing. Met. In the present invention, since such machining is not required, the size of the air dynamic pressure bearing can be further reduced. A spindle motor according to the present invention, in which a rotor is supported on a stator by using a radial dynamic pressure bearing composed of a laminated cylindrical bearing member and a cylindrical bearing member having various features as described above, is small, inexpensive, and easy to manufacture. In addition, since the radial dynamic pressure generating groove of the air dynamic pressure bearing has no direction, it can also be rotated forward and reverse, and is most suitable for a rotating body device for driving a rotating body such as a magnetic disk, an optical disk or a polygon mirror. It is.

[Brief description of the drawings]

FIG. 1 is a longitudinal section of an embodiment of a radial dynamic pressure bearing constituted by a laminated cylindrical bearing member having three cylindrical pieces having an eccentric shaft hole and a cylindrical bearing member having a flat inner peripheral surface. FIG.

FIG. 2 is a longitudinal section of an embodiment of a radial dynamic pressure bearing constituted by a laminated cylindrical bearing member having five cylindrical pieces having eccentric shaft holes and a cylindrical bearing member having a flat inner peripheral surface. FIG.

FIG. 3 is a cross-sectional view of the radial dynamic pressure bearing of FIG. 1 or FIG.

4 is an eccentric donut formed between one cylindrical piece having an eccentric shaft hole and a cylindrical bearing member having a flat inner peripheral surface in the radial dynamic pressure bearing of FIG. 1 or FIG. 2; FIG. 2 is a diagram showing exaggeratedly shaped voids.

FIG. 5 is a perspective view of a partial cross section of a conventional radial dynamic pressure bearing.

FIG. 6 is a perspective view of a partial cross section of a conventional forward / reverse rotating radial dynamic pressure bearing.

FIG. 7 is a cross-sectional view of one embodiment of a rotary shaft type spindle motor according to the present invention.

FIG. 8 is a perspective view of a floppy device using a spindle motor according to the present invention as a drive source of an HDD medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concentric shaft 2 Cylindrical bearing member 2a, 2b 2c, 2d, 2e Cylindrical piece 3 Cylindrical bearing member 4 Upper cover 5 Lower cover 6 Cylindrical bearing member 7 Cylindrical bearing member 8 Conducting hole G Dynamic pressure generating groove 10 Stator Base plate 11 Stator coil 12 Rotor magnet 13 Hub 14 Media SM Spindle motor

Claims (4)

[Claims] 1. A forward / reverse rotating spindle motor having a rotor supported on a stator by a dynamic pressure bearing, wherein the dynamic pressure bearing has three or more flat cylindrical pieces having the same shape and dimensions having an eccentric shaft hole. Are laminated by aligning the eccentric shaft holes and sequentially changing the direction at a constant angle, and press-fitting and fixing one concentric shaft into the eccentric shaft hole to form regular irregularities on the outer peripheral surface. A spindle motor comprising: a column-shaped bearing member; and a cylindrical bearing member having a flat inner peripheral surface. 2. The spindle motor according to claim 1, wherein the predetermined angle is 180 degrees. 3. The spindle motor according to claim 1, wherein the predetermined angle is 120 degrees. 4. A spindle motor in which a rotor is supported on a stator by a dynamic pressure bearing and is rotatable in forward and reverse directions, wherein said dynamic pressure bearing has three or more flat eccentric shaft holes having the same shape and dimensions. Laminating cylindrical pieces by aligning the eccentric shaft holes and changing the direction at a fixed angle in order, and pressing and fixing one concentric shaft into the eccentric shaft holes to form regular irregularities on the outer peripheral surface. A rotating body device comprising: a rotary motor as a drive source of a rotating body, wherein the rotating body comprises a cylindrical roller bearing member and a cylindrical bearing member having a flat inner peripheral surface.