JP2873209B2 - Spindle motor with fixed rotating shaft with magnetic bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor used for a magnetic recording / reproducing apparatus such as a hard disk drive (HDD), and more particularly, to a spindle motor with a rotary shaft fixed to a housing assembly. The present invention relates to a spindle motor having a fixed rotating shaft having a magnetic bearing that rotates.

[0002]

2. Description of the Related Art Generally, a hard disk drive (HDD)
Alternatively, a spindle motor used in a magnetic recording / reproducing apparatus is a ball bearing (Ball Bearin) as shown in FIG.
g) Types are often used. Recently, oil dynamic fluid bearings (or air dynamic fluid bearings) as shown in FIG. 2 have been developed and used, but these bearings have the following disadvantages.

That is, the ball bearing (a) shown in FIG.
In the case of (1), one pair is used for each of the upper and lower stages of the rotating shaft (b). First, the degree of rotation differs depending on the accuracy of the ball, second, noise and vibration are large, and third, Since the particles of lubricating oil (grease) scatter and damage the hard disk, a seal or a sealed structure (e) is required to block the hard disk. Fourth, if there is only a limit to high-speed rotation, Fifth, it is vulnerable to impact.

The dynamic pressure bearing (c) shown in FIG.
While maintaining a gap between the rotating shaft (b) and the hub (d), a groove or a comb-like processing is performed inside to generate dynamic pressure as oil or air, and this is maintained. First, an oil prevention structure is required, second, a metal contact noise is generated when starting and stopping, thirdly, friction is large, and fourthly, low-speed rotation is unstable. Fifth, the temperature characteristics are non-uniform.

[0005] In addition, the above two types of conventional bearings are disadvantageous in that they are difficult to manufacture together and are expensive.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been devised to solve the above-mentioned various problems in the prior art, and an object of the present invention is to provide a rotary shaft and an inner cylinder of a hub. Spindle motor with a rotating shaft fixed with a magnetic bearing, which rotates without friction by the repulsive force of the same pole and the attractive force of the other pole, with a magnet having magnetism interposed between the parts. Is to provide.

[0007]

A characteristic configuration for this is a housing assembly having a stator on the inside and a rotating shaft erected in the center, and an inner peripheral edge of an outer cylinder portion on the housing assembly. With the rotor magnet in place, the inner cylinder portion is configured to be fitted into the rotating shaft and rotated by a hub, and each shaft portion magnet having a different pole up and down is inserted into the rotating shaft, and In the spindle motor, each hub magnet having a different pole vertically is attached to the inner peripheral surface of the inner cylindrical portion, and the hub is allowed to rotate without contact while the hub floats due to the repulsive force and attractive force of the magnet. When the shaft magnets of the shaft are arranged vertically N and S, the magnets of the outer hub portion are similarly arranged vertically N and S so that the repulsive force of the magnets inside and outside mutually acts greatly. The magnetic center of the upper hub magnet The magnetic center of the lower shaft magnet is higher than the magnetic center of the lower shaft magnet, and the magnetic center of the lower hub magnet is lower than the magnetic center of the lower shaft magnet. A rotating shaft with a working magnetic bearing resides on a fixed spindle motor.

[0008]

FIG. 3 is a sectional view showing a spindle motor according to the present invention, in which a housing assembly (1) having a stator (11) inside and a rotating shaft (3) standing upright in the center. ), And the inner cylindrical portion (21) is rotated by the rotating shaft while the rotor magnet (23) is provided on the inner peripheral edge of the outer cylindrical portion (22).
And a hub (2) that is fitted into and rotates with (3).

The rotating shaft (3) fixed to the housing assembly (1) has respective shaft magnets (4
a) and (4b), and the hub magnets (5a) and (5a), each having a different pole vertically, are similarly provided on the inner peripheral surface of the inner cylindrical portion (21) of the hub (2). (5b) is attached.

More specifically, a pair of upper and lower shaft magnets (4a) and (4b) are connected to the middle stage of the rotating shaft (3).
This magnet has a cylindrical shape and is connected by fitting a shaft, and the arrangement of upper and lower poles is different between an upper half N pole and a lower half S pole.

Further, a pair of upper and lower hub magnets (5a) and (5b) are also provided on the inner peripheral surface of the inner cylindrical portion (21) of the hub (2). As for the upper and lower poles, the upper part is the north pole and the lower part is the S pole like the shaft magnet of the rotating shaft (3).
Arranged in poles.

Therefore, the rotary shaft (3) of the present invention and the hub (2)
As shown in detail in FIG. 3, due to the horizontal repulsion of the north pole and the north pole of the upper half and the horizontal repulsion of the south and south poles, they rotate without touching each other. The poles of these magnets are the same even if they are turned upside down.

As shown in FIG. 4, the magnet (4a) above the shaft portion has a magnetic center (A) whose magnet center (A) is above the hub portion (5a).
Since the magnetic center (B) is lower than the magnetic center (B), the magnet (4b) on the lower side of the shaft receives a repulsive force and attractive force, and its magnetic center (C) has the magnetic center (C) of the magnet (5b) on the lower side of the hub. Center (D)
Because it is at a higher position, it receives repulsive and attractive forces upward.

Therefore, the shaft magnets (4a) and (4b) and the hub magnets (5a) and (5B) are floated and stabilized in a state of being balanced with each other. Such a force does not change. At this time, the stronger the magnetic force of the magnet, the stronger the strength can be adjusted.

On the other hand, the present invention can be implemented in other modes as shown in FIGS.

FIG. 5 shows a case in which a circumferential groove (5c) is formed at the boundary between the upper and lower hub magnets (5a) and (5b) to increase the gap between the magnets facing this and the middle section. is there.

[0017] In this case, since the flux of the magnetic force in the upper and lower portions becomes stronger due to the Coriolis effect, the repulsive force of the effective portion of the magnetic force can be further increased.

FIG. 6 shows the hub magnets (5a) and (5) of the present invention.
A non-magnetic metal plate (6) is attached to the inside of b), and the degree of magnetic force can be controlled for the shaft magnets (4a) and (4b) at the center of the inside. Things.

FIG. 7 shows the hub magnet (5) as shown in FIG.
A metal plate (6) made of a non-magnetic material is attached inside of (a) and (5b), and a circumferential groove (6) is formed in the middle portion of the metal plate (6) as shown in FIG.
a) wherein the Coriolis effect is obtained while controlling the degree of magnetic force.

FIG. 8 shows that the shaft magnets (4a) and (4b) are formed in a cylindrical shape instead of fitting the shaft magnets around the rotation shaft (3). Since the diameter is reduced by fitting the shaft magnet around the rotation axis, it is possible to follow a reduction-directional design.

FIG. 9 shows an example in which a non-magnetic metal plate (6) is attached to the hub magnets (5a) and (5b), but is attached to the outer peripheral edge instead of the inner peripheral edge. Again, it allows the degree of magnetic force to be managed.

FIG. 10 shows the hub magnet (5) as shown in FIG.
A non-magnetic metal plate (6) is attached inside a) and (5b), and a circumferential groove (6a) is formed in the middle part of the metal plate (6). By forming a circumferential groove (4c) in the middle of the cylindrical surface also in the magnets (4a) and (4b), the Coriolis effect is increased while controlling the degree of magnetic force.

FIG. 11 shows that the inner bottom surface of the hub (2) is
A magnetic force shielding plate (7) made of (Fe) material is attached, and the magnetic force generated from the shaft magnets (4a) and (4b) and the hub magnets (5a) and (5b) is used for other hard disk drives. Care has been taken not to affect the parts.

[0024]

As described above, the present invention provides:
Instead of conventional general bearings, the magnets (4a) and (4b) of the shaft of the fixed rotating shaft (3) and the magnets of the hub (5a) and (5a) in the inner cylinder (21) Since the bearing function is performed as 5b), there is no contact at the time of stoppage as well as at the time of rotation.Therefore, not only there is no noise and vibration, but also there is an advantage that rotation is uniform at low speed and high speed, Characteristics change due to temperature change is small, asynchronous rotation amplitude is very small, especially the material of magnet can be selected variously such as metal, plastic, rubber, etc. In addition, the strength, gap, length etc. can be changed appropriately to improve motor characteristics Since it is easy to design together, it can be widely used.

Although the concept of the present invention has been specifically described with reference to the above embodiment, the present invention is not limited to the above embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. Absent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional spindle motor having a ball bearing.

FIG. 2 is a sectional view of a conventional spindle motor having a dynamic pressure bearing.

FIG. 3 is a sectional view of a spindle motor according to the present invention.

FIG. 4 is a sectional view of a main part of the present invention.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a sectional view showing another embodiment of the present invention.

FIG. 8 is a sectional view showing another embodiment of the present invention.

FIG. 9 is a sectional view showing another embodiment of the present invention.

FIG. 10 is a sectional view showing another embodiment of the present invention.

FIG. 11 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 1: Housing assembly 2: Hub 3: Rotating shaft 4a, 4b: Shaft magnet 4c: Circumferential groove 5a, 5b: Hub magnet 6: Metal member 7: Magnetic force blocking plate

Claims (8)

(57) [Claims] 1. A housing assembly having a stator on the inside and a rotating shaft standing upright in the center, and an inner cylindrical portion attached to the rotating shaft while a rotor magnet is provided on an inner peripheral edge of an outer cylindrical portion on the housing assembly. Each of the shaft magnets having different poles in the vertical direction is inserted into the rotating shaft, and each of the magnetic poles in the vertical direction is fixed to the inner peripheral surface of the inner cylindrical portion of the hub. In a spindle motor provided with a hub magnet and capable of rotating without contact while the hub floats due to the repulsive and attractive forces of the magnet, when the shaft magnets of the rotating shaft are arranged vertically N and S, The magnets of the outer hub are also arranged in the upper and lower directions N and S in the same manner so that the repulsive force of the inner and outer magnets acts greatly, and the magnetic center of the upper hub magnet is changed to the magnetic center of the upper shaft magnet. Higher and above the lower c A rotating center having a magnetic bearing, wherein the magnetic center of the lower magnet is lower than the magnetic center of the lower shaft magnet so that each repulsive force acts toward the middle point of the lower magnet. Spindle motor with fixed axis. 2. A method according to claim 1, wherein a circumferential groove is formed from an intermediate upper contact portion of said hub magnet to an inner surface thereof, so that the magnetic force of the upper and lower portions is made more effective by the Coriolis effect. The spindle motor according to 1. 3. A method according to claim 1, wherein a circumferential groove is formed from an intermediate upper contact portion of said shaft portion magnet to an outer peripheral surface thereof, and a magnetic force in upper and lower portions thereof is made more effective by a Coriolis effect. The spindle motor according to 1. 4. The spindle motor according to claim 1, wherein a thin non-magnetic metal plate is joined to the inner peripheral surface of said hub magnet to control the degree of magnetic force. 5. The spindle motor according to claim 4, wherein said non-magnetic metal plate is joined to an outer peripheral surface of a hub magnet to control a degree of magnetic force. 6. A non-magnetic metal plate having a circumferential groove formed at a middle height thereof so that the magnetic force of the upper and lower outer portions is made more effective by the Coriolis effect. 5. The spindle motor according to 5. 7. The spindle motor according to claim 1, wherein said shaft magnet is formed in a cylindrical shape to constitute a middle portion of said rotary shaft. 8. The spindle motor according to claim 1, wherein a magnetic force blocking plate is provided on an inner bottom surface of said hub to prevent magnetic force from leaking out.