JPH0666280U - Drive device for magnetic disk type storage device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent pure tone without changing the structure such as the number of poles of the motor or the shape of parts. [Structure] As an example, the motor base 8 has nine (= N)
The stator core 9a is fixed along the circumferential direction, and the stator coil 9b is wound around the stator core 9a. As an example, a rotor magnet 10 having 12 poles (= P) is attached to the inner peripheral surface of the hub 4 so as to face the core 9a and the coil 9b, and the rotor magnet 10 has a radially magnetized portion having a reverse polarity in the circumferential direction. Are alternately arranged, and are multi-pole magnetized so that the skew angle θ has 0 ° <θ ≦ 50 ° in the axial direction, and are unipolarly magnetized in a predetermined direction such as the axial direction. In this example, the least common multiple LCM (P, N) of the number N of stator cores and the number P of rotor magnet poles is 36, and the energization switching frequency fs in the case of three-phase bidirectional driving is fs = (12 poles / 2). × 3 phases × 2 (both directions) = 36, and the cogging order k is k =
(1/2) LCM (P, N) and K ≠ LCM (P,
N).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drive device of a magnetic disk type storage device such as an HDD (hard disk drive device), and particularly to the influence of cogging generated by the change of magnetic flux when the magnetic pole of the rotor passes through the magnetic pole of the stator. The present invention relates to a drive device for a magnetic disk type storage device that reduces noise caused by noise.

[0002]

[Prior art]

 Conventionally, in this type of drive device, for example, when the number of poles P of the rotor magnet is 12 and the number of slots N of the stator is 9, the least common multiple LCM (P, N) is 36. The energization switching frequency fs in the case of three-phase bidirectional driving is: fs = (12 poles / 2) × 3 phases × 2 (bidirectional) = 36. Further, the cogging order k becomes 36 times as shown in FIG. 9, and thus k = LCM (P, N) = fs.

[0003]

[Problems to be solved by the device]

 However, in the above conventional device, when the frequency of noise was analyzed, a peak value (pure tone) was generated at 2162.5 Hz as shown in FIG. Therefore, there is a problem in that this pure tone is uncomfortable in hearing. In recent years, as HDDs have become smaller and personal computers have become more and more used, noise reduction has been required, and such pure tones are being improved.

In view of the above-mentioned conventional problems, an object of the present invention is to provide a drive device of a magnetic disk type storage device capable of preventing a pure tone without changing a motor structure.

[0005]

[Means for Solving the Problems]

 In the present invention, in order to achieve the above object, the least common multiple LCM (P, N) of the number N of slots of the stator core and the number P of poles of the rotor magnet and the cogging order k are different. That is, according to the present invention, in order to rotate a hub for mounting a magnetic disk, a stator core having N slots and a rotor magnet having P poles are provided, and the number N of slots and the number P of poles are provided. Of the magnetic disk type storage device in which the least common multiple LCM (P, N) of the magnetic field and the energization switching frequency fs of the status coil are equal to each other. In the present invention, there is provided a drive device for a magnetic disk type storage device, wherein the cogging order k and the least common multiple LCM (P, N) are made different by magnetizing a single pole in a predetermined direction of the rotor magnet. It

[0006]

[Action]

 In the present invention, as described above, the rotor magnet is unipolarly magnetized in a predetermined direction with a small strength, and the least common multiple L CM (P, N) of the number N of slots of the stator core and the number P of poles of the rotor magnet and the cogging order. Since k was made different, pure tone could be prevented without changing the structure such as the number of poles of the motor or the shape of parts.

[0007]

【Example】

 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 type storage device according to the present invention, and FIG. 2 shows a hub assembly obtained by incorporating the rotor magnet shown in FIG. 1 into a hub. FIG. 3 is a side sectional view, FIG. 3 is a plan view showing the hub assembly of FIG. 2, FIG. 4 is a plan view showing a stator core, and FIG. 5 is a drive device of a disk type storage device having a rotor magnet and a stator core of FIGS. FIG. 6 is a side view showing the outline, FIG. 6 is an explanatory view showing the cogging order of the embodiment, and FIG. 7 is an explanatory view showing the frequency spectrum of noise of the embodiment.

First, an outline of a drive device for a disk type storage device according to the present invention will be described with reference to FIG. As an example, this drive device is hermetically sealed in a casing composed of an HDD top plate 1a and a base plate 1b, and a printed circuit board 2 of the HDD is fixed below the base plate 1b. A hub 4 is fixed around the shaft 3, which is the central axis, at the upper and lower ends by screws 6 and 7, respectively. The shaft 3 and the hub 4 are attached to the motor base 8 via two annular ball bearings 105. It is rotatably supported. The disk 108a is fixed to the outer peripheral surface of the hub 4 by a clamper 5 and a screw 6.

The outer periphery of the motor base 8 is fixed to the base plate 1b of the HDD, and as shown in FIG. 4, the motor base 8 has nine (= N) stator cores 9a and stator coils 9b in the circumferential direction. Is fixed along. As shown in FIG. 3, a rotor magnet 10 having magnetized portions arranged in the circumferential direction is fixed to the inner peripheral surface of the hub 4 so as to face the core 9a and the coil 9b. Therefore, during motor operation, the shaft 3 and the hub 4 rotate with respect to the motor base 8 due to 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 multi-pole magnetized, and has 12 poles (P = 12) in this example. The magnetizing 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 portions are alternately arranged in the circumferential direction in such a manner that NSs are interchanged. Further, each magnetized portion is inclined at a skew angle θ of 0 ° <θ ≦ 50 ° with respect to the axial direction as shown in FIG. The configuration so far is no different from the conventional rotor magnet.

In the present invention, the rotor magnet 10 is magnetized in a predetermined direction in addition to the above-mentioned multi-pole magnetization. That is, as shown by the arrow in FIG. 1 showing an embodiment, the rotor magnet 10 is magnetized with a single pole in the axial direction. The strength of this single-pole magnetization is smaller than that of the multi-pole magnetization in the radial direction. In such a configuration, the least common multiple L CM (P, N) is 36, and the energization switching frequency fs in the case of three-phase bidirectional driving is fs = (12 poles / 2) × 3 phases × 2 ( Both directions) = 36. When the cogging order k was experimentally determined, it was k = (1/2) LCM (P, N) as shown in FIG. 6, and no pure tone was generated as shown in FIG. . In the figure, unipolar magnetization is indicated by ns and multipole magnetization is indicated by NS.

Further, in such a configuration, since the degree of axial magnetization of the rotor magnet 10 is very small, the performance such as torque is not adversely affected, and the number of poles P and P It is possible to prevent pure tone without changing the number N of stators, the shape of slots, and the like.

Next, a rotor magnet according to a second embodiment of the present invention will be described. In the first embodiment, the rotor magnet 10 is magnetized in a single pole in the axial direction, but in the second embodiment, as shown in FIG. 8, it has the same radial multi-pole magnetization as in the embodiment. In the radial direction, that is, in the radial direction radiated from the center, it is monopolarly magnetized with a small intensity. As a result, the least common multiple LCM (P, N) did not match the cogging order k, and pure tone did not occur at all.

[0014]

[Effect of device]

 As described above, according to the present invention, the rotor magnet is unipolarly magnetized in a predetermined direction with a small strength to obtain the least common multiple LCM (P) of the number N of slots of the stator core and the number P of poles of the rotor magnet. , N) and the cogging order k were made different, and pure tones could be prevented without changing the motor structure.

[Brief description of 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 type 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.

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

FIG. 4 is a plan view showing stator cores which face each other when the rotor magnets of FIGS. 1 to 3 are incorporated.

5 is a side sectional view showing an outline of a drive device of a disk type storage device having the rotor magnet and the stator core of FIGS. 1 to 4. FIG.

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 according to 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 multi-pole magnetized portion S multi-pole magnetized portion n single pole magnetized portion (magnetization direction) s single pole magnetized portion (magnetization direction)

Claims (1)

[Scope of utility model registration request] 1. A stator magnet having N slots and a rotor magnet having P poles for rotating a hub for mounting a magnetic disk.
And the least common multiple LCM (P, N) of the number of poles P and the energization switching frequency fs of the stator coil match, in the magnetic disk type storage device driving device By unipolarly magnetizing the rotor magnet in a predetermined direction with a small strength, the cogging order k and the least common multiple LCM (P,
A drive device for a magnetic disk type storage device, characterized in that N) is different.