JP2607780Y2 - Drive for magnetic disk storage device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a magnetic disk type storage device such as an HDD (hard disk drive device), and more particularly to a drive device for a magnetic flux of a rotor which fluctuates when passing through a magnetic pole of a stator. The present invention relates to a drive device for a magnetic disk storage device that reduces noise caused by the effect of cogging.

Conventionally, in this type of driving device, for example, the number of poles P of the rotor magnet is 12, and the number of slots N of the stator is N.
Is 9, the least common multiple LCM (P, N) is 36
It is. Further, the energization switching frequency fs in the case of the three-phase two- way energization method is three-phase twelve-pole, so that fs = three-phase × 12 = 36 Further, the cogging order k is k = LCM (P, N) = 36 , which coincides with the energization switching frequency fs.

[0003]

An invention is, however, in the above conventional apparatus, when the rotational speed is 3600 rpm, was analyzed the frequency of the noise, 216 0H as shown in FIG. 10
A peak value (pure tone) occurred at z.
Therefore, there is a problem that the pure tone is unpleasant for the auditory sense ear. In recent years, miniaturization of HDDs has progressed, and with the advance of personal use of computers, low noise has been demanded, and such pure tones have been highlighted.

The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide a drive apparatus for a magnetic disk storage device capable of preventing a pure tone without changing a motor structure.

[0005]

In order to achieve the above object, the present invention comprises a stator core having N slots and a rotor magnet having P poles for rotating a hub on which a magnetic disk is mounted, In a magnetic disk storage device drive device in which the least common multiple LCM (P, N) of the number of slots N and the number of poles P coincides with the energization switching frequency fs of the stator coil, each of the P poles of the rotor magnet is radially connected. Cogging order k by magnetizing the rotor magnet in the axial direction with a magnetizing strength that is weaker than the radial magnetizing strength of each of the poles and that does not generate a pure tone. There is provided a driving device of a magnetic disk storage device which is characterized in that set to be 1/2 of the least common multiple LCM (P, N).

[0006]

[Function] In the present invention, the rotor magnet
The least common multiple LC of the number N of slots in the stator core and the number P of poles of the rotor magnet by unipolar magnetization with minute strength in the axial direction
Since the cogging order k is different from M (P, N), the pure tone can be prevented without changing the structure such as the number of poles of the motor and the shape of the parts.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a rotor magnet which is a main part of an embodiment of a drive device for a disk storage device according to the present invention. FIG. 2 is a side view showing a hub assembly obtained by incorporating the rotor magnet of FIG. 1 into a hub. FIG. 3 is a sectional view, and FIG.
FIG. 4 is a plan view showing a stator core, FIG. 5 is a side view schematically showing a drive device of a disk storage device having a rotor magnet and a stator core shown in FIGS. 1 to 4, and FIG. FIG. 7 is an explanatory diagram showing a cogging order of an example, and FIG. 7 is an explanatory diagram showing a frequency spectrum of noise of the embodiment.

First, referring to FIG. 5, an outline of a drive device of a disk type storage device according to the present invention will be described. As an example, this drive device is sealed in a casing composed of a top plate 1a and a base plate 1b of the HDD, and a printed circuit board 2 of the HDD is fixed below the base plate 1b. Also, the shaft 3 which is the central axis
A hub 4 is fixed at its upper and lower ends by screws 6 and 7, respectively. The shaft 3 and the hub 4 are connected to a motor base 8 by two annular ball bearings 10.
5 so as to be rotatable. Disk 108
a is a clamper 5 and a screw 6
It is fixed by.

The outer periphery of the motor base 8 is fixed to a base plate 1b of the HDD.
As shown in the figure, as an example, nine (= N) stator cores 9
a and the stator coil 9b are fixed along the circumferential direction. As shown in FIG. 3, a core 9 is provided on the inner peripheral surface of the hub 4.
The rotor magnet 10 whose magnetized portions are arranged in the circumferential direction so as to face the coil a and the coil 9b is fixed. Therefore, during motor operation, the shaft 3 and the hub 4 rotate with respect to the motor base 8 by the rotation of the rotor magnet 10.

FIG. 1 shows a rotor magnet 10 according to a first embodiment of the present invention. As shown in FIG. 1, the rotor magnet 10 of the first embodiment is multipolar magnetized, and has 12 poles (P = 12) in this example. The magnetization direction of each magnetized portion is the radial direction, that is, the radial direction, and the inner peripheral portion of the rotor magnet 10 is N and the outer peripheral portion is S. The radially magnetized portion is N
S are alternately arranged in the circumferential direction so that S is exchanged.
Also, each magnetized portion is at 0 ° to the axial direction as shown in FIG.
<Θ ≦ 50 ° skew angle θ. The configuration so far is not different from the conventional rotor magnet.

In the present invention, the rotor magnet 10 is subjected to axial unipolar magnetization in addition to the above multipolar magnetization. That is, as shown by an arrow in FIG. 1 showing one embodiment, the rotor magnet 10 is magnetized with a single pole in the axial direction. Incidentally, the strength of the single-pole magnetization is small compared to the multi-pole magnetization in the radial direction, i.e. a single axial direction of the rotor magnet 10
Polar magnetization strength is much more than radial multipolar magnetization
It is small enough to provide a pure tone prevention effect . In such a configuration, the least common multiple LCM (P,
N) is 36, and the energization switching frequency fs in the case of the three-phase two- way energization method is fs = 36. Then, was determined by the cogging degree k experiments, becomes k = 18 as shown in FIG. 6 also, pure tone as shown in FIG. 7 is about 50
At mV, it was about 1/10 of the conventional example . In the drawing, the unipolar magnetization is indicated by ns, and the multipolar magnetization is indicated by NS.

In such a configuration, the degree of magnetization in the axial direction of the rotor magnet 10 is very small, so that the performance such as torque is not adversely affected. Pure tone can be prevented without changing the number N of stators, the slot shape, and the like.

[0013]

As described above, according to the present invention, the rotor magnet is monopolarly magnetized with a minute strength in the axial direction, and the least common multiple LCM of the number of slots of the stator core and the number of poles P of the rotor magnet is performed. When the cogging order k is different from (P, N), the vibration due to the coil switching is changed.
Since the motion did not resonate with the cogging frequency, a pure tone could be prevented without changing the motor structure.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a rotor magnet which is a main part of an embodiment of a drive device of a disk storage device according to the present invention.

FIG. 2 is a side sectional view showing a hub assembly obtained by incorporating the rotor magnet of FIG. 1 into a hub.

FIG. 3 is a plan view of the hub assembly of FIG. 2;

FIG. 4 is a plan view showing a stator core facing when the rotor magnet of FIGS. 1 to 3 is assembled.

FIG. 5 is a side sectional view schematically showing a drive device of the disk storage device having the rotor magnet and the stator core shown in FIGS. 1 to 4;

FIG. 6 is an explanatory diagram showing the cogging order of the first embodiment.

FIG. 7 is an explanatory diagram showing a frequency spectrum of noise of the first embodiment.

FIG. 8 is a perspective view showing a rotor magnet of a second embodiment.

FIG. 9 is an explanatory diagram showing a cogging order of a conventional example.

FIG. 10 is an explanatory diagram showing a frequency spectrum of noise in a conventional example.

[Explanation of symbols]

 4 Hub 9a Stator core 9b Stator coil 10 Rotor magnet N Multipole magnetized part S Multipole magnetized part n Unipolar magnetized part (magnetization direction) s Single pole magnetized part (magnetization direction)

Claims (1)

(57) [Scope of request for utility model registration] A stator core having N slots and a rotor magnet having P poles are provided for rotating a hub on which a magnetic disk is mounted, and a least common multiple LCM (PCM) of the slot number N and the pole number P is provided. , N) and the driving frequency fs of the stator coil coincide with each other, the P poles of the rotor magnet are radially magnetized, and the axial direction of the rotor magnet is It is weaker than the radial magnetization strength of each pole, and
The cogging order k is reduced by the least common multiple LCM (P,
N) The drive device for a magnetic disk type storage device, wherein the drive amount is set to 1/2 of N).