JPH066946A - Motor for magnetic disc drive - Google Patents

Abstract

PURPOSE:To provide a motor for use with a magnetic disc drive having superior characteristics that reduces and interrupts electromagnetic noise and PWM noise which adversely affect a head of a magnetic disc drive, and that can resolve read/write failures. CONSTITUTION:A cylindrical shield plate 19 or a cylindrical shield plate 19 having an opening that is formed on the opposite side to a head of a magnetic disc driving device is disposed in a cylindrical section 24 of a bracket 3. In addition, an opening of a stator core 5 is aligned with the direction of the head, whereby electromagnetic noise and PWM noise can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a brushless motor for driving a disk in which at least one magnetic disk is mounted and driven to rotate in a magnetic disk drive, and more particularly to an inner diameter portion of a hub on which the magnetic disk is mounted. The present invention relates to the structure of an outer rotor type brushless motor (hereinafter referred to as a motor) fixed to a magnet.

[0002]

2. Description of the Related Art A magnetic disk drive device is significantly thinned in height due to demands for thinning, miniaturization, large capacity, and low power consumption of a computer system, and the size thereof is 8 inches to 5 inches. 0.25 inch, 3.5
The mainstream has moved to the inch type, and in recent years 2.5 inches, 1.
8-inch type has appeared. Also, due to the spread of databases, engineering, and workstations, there is a growing need for larger capacity and a trend toward lower power consumption, and there is a demand for motor drive using the PWM method.

A conventional motor will be described below with reference to the drawings. FIG. 6 is a sectional view of a conventional motor, and FIG. 7 is a plan view of the conventional motor.

In FIGS. 6 and 7, 1 is a fixed shaft of the motor,
Reference numeral 7 denotes an upper bearing attached to the upper portion of the fixed shaft 1, 8 denotes a lower bearing attached to the central portion of the fixed shaft 1, and 12 denotes a spacer, which is located between the upper bearing 7 and the lower bearing 8.
Reference numeral 2 is a hub for mounting a magnetic disk, and 3 is a bracket. The fixed shaft 1 is mounted in the central portion and extends to the magnetic disk mounting side 29. The bracket 3 is fixed to the magnetic disk drive device 28 with a mounting screw c30. Four
Is a cylindrical rotor magnet fixed to the hub 2, and 5 is a stator core provided at a position facing the rotor magnet 4, and fixed to the lower portion of the fixed shaft 1. Reference numeral 6 is a winding wound around the stator core 5. A stator substrate 9 is attached to the bracket 3, and the stator substrate 9 has a position detecting element 15 for controlling the excitation of the winding 6.
Are arranged. 11 is an upper magnetic fluid seal,
The upper bearing 7, which holds the magnetic fluid a16 between itself and the fixed shaft 1,
The grease is prevented from scattering from the lower bearing 8. Reference numeral 14 denotes a magnetic fluid seal holder a that holds the upper magnetic fluid seal 11 and is fixed to the hub 2. Reference numeral 18 denotes a lower magnetic fluid seal, which holds the magnetic fluid b17 between itself and the hub 2 to prevent grease from scattering from the upper bearing 7 and the lower bearing 8. A magnetic fluid seal holder b 13 holds a lower magnetic fluid seal 18 and is attached to the central portion of the fixed shaft 1. Reference numeral 10 is a preload spring, which is located between the lower bearing 8 and the magnetic fluid seal holder b13 and applies a preload to the upper bearing 7 and the lower bearing 8. Reference numeral 19b is a shield plate b, which is attached to the notch 23 of the bracket 3.

[0005]

However, in the above-mentioned conventional structure, since the shield plate is attached in parallel to the noise generation direction, the effect of reducing the electromagnetic noise generated from the motor and the PWM noise of the PWM drive is obtained. Since it is small, it has a problem that it adversely affects the head and causes a read / write defect.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a motor that reduces electromagnetic noise and PWM noise.

[0007]

To achieve this object, a motor according to the present invention has a bracket cylindrical portion provided with a cylindrical shield plate having a cylindrical shape or an opening portion, and further, an opening portion of a stator core and a head direction. Have the same structure.

[0008]

With this structure, the PWM noise due to the PWM drive is directly cut off, and the electromagnetic noise due to the excitation of the winding and the opening of the stator core where the PWM noise is small are aligned with the head direction, so that the noise to the head is reduced. It can be reduced. Further, the magnetic flux leaking from the magnet can be blocked.

[0009]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

The same parts as those of the conventional structure are designated by the same reference numerals as those of the conventional example, and the description thereof will be omitted.

FIG. 1 is a sectional view of a motor according to the first embodiment of the present invention, and FIG. 2 is a plan view of the motor according to the first embodiment of the present invention.

1 and 2, reference numeral 19 denotes a cylindrical shield plate, which is attached to the cylindrical portion 24 of the bracket 3.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view of a motor according to the second embodiment of the present invention, and FIG. 4 is a plan view of the motor according to the second embodiment of the present invention.

In FIGS. 3 and 4, 1a is a fixed shaft a of the motor, and 12a is a spacer a, which is located between the upper bearing 7 and the lower bearing 8. Reference numeral 2a is a hub a for mounting a magnetic disk, 3a is a bracket a, and a fixed shaft a1a is mounted in the central portion and extends to a magnetic disk mounting side a29a. The bracket a3a is fixed to the magnetic disk drive a28a with a mounting screw d30a. 4a is a cylindrical rotor magnet a fixed to the hub a2a, 5
Reference numeral a denotes a stator core a provided at a position facing the rotor magnet a4a, and is fixed to a lower portion of the fixed shaft a1a. 6a is a winding a wound around the stator core a5a. Reference numeral 9a denotes a stator substrate a, which is attached to the bracket a3a with attachment screws b22, and a position detection element a15a for controlling the excitation of the winding a6a is arranged on the stator substrate a9a. A magnetic fluid seal holder c that holds the upper magnetic fluid seal 11 is fixed to the hub a2a. A magnetic fluid protection plate 20 is attached to the magnetic fluid seal holder c14a. Reference numeral 13a denotes a holder, which is attached to the central portion of the fixed shaft a1a to reduce the radial gap between the holder 13a and the hub a2a and the radial gap between the holder 13a and the lower bearing 8 to reduce grease scattering from the upper bearing 7 and the lower bearing 8. Is being prevented. 10a is a preload spring a
It is located between the lower bearing 8 and the holder 13a, and preloads the upper bearing 7 and the lower bearing 8. Reference numeral 19a denotes a cylindrical shield plate a having an opening, and a bracket a
The shield plate a19a is attached to the cylindrical portion a24a of 3a with an attaching screw a21, the opening of the shield plate a19a is provided on the opposite side to the head direction 25 of the magnetic disk device, and the angles θ1 and θ2 are arranged equal to the head direction 25. .

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings. The same parts as those in the configuration of the second embodiment of the present invention are designated by the same reference numerals and the description thereof is omitted.

FIG. 5 is a plan view of the inside of the motor according to the third embodiment of the present invention. In FIG. 5, 9b is a stator substrate b, and a mounting screw b22 is attached to the bracket a3a.
It is installed in. Reference numeral 26 is a stator core opening portion, 27 is a status core salient pole portion, and the head direction 25
And the positions of the stator core openings 26 are the same.

[0018]

As described above, according to the present invention, the bracket cylindrical portion is provided with the cylindrical shield plate having the cylindrical shape or the opening portion, and the opening portion of the stator core is aligned with the head direction, so that the electromagnetic noise and the PWM noise are generated. In addition, the magnetic flux leaking from the magnet can be blocked, and an excellent motor that solves read / write defects can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a motor according to a first embodiment of the present invention.

FIG. 2 is a plan view of the motor according to the first embodiment of the present invention.

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

FIG. 4 is a plan view of a motor according to a second embodiment of the present invention.

FIG. 5 is a plan view of the inside of the motor according to the third embodiment of the present invention.

FIG. 6 is a sectional view of a conventional motor

FIG. 7 is a plan view of a conventional motor

[Explanation of symbols]

 1 fixed shaft 1a fixed shaft a 2 hub 2a hub a 3 bracket 3a bracket a 4 rotor magnet 4a rotor magnet a 5 stator core 5a stator core a 6 winding 6a winding a 7 upper bearing 8 lower bearing 9 stator substrate 9a stator substrate a 9b Stator substrate b 10 Preload spring 10a Preload spring a 11 Upper magnetic fluid seal 12 Spacer 12a Spacer a 13 Magnetic fluid seal holder b 13a Holder 14 Magnetic fluid seal holder a 14a Magnetic fluid seal holder c 15 Position detection element 15a Position detection element a 16 magnetic fluid a 17 magnetic fluid b 18 lower magnetic fluid seal 19 shield plate 19a shield plate a 19b shield plate b 20 magnetic fluid protection plate 21 mounting screw a 22 mounting screw b 23 cutout portion 24 cylindrical portion 4a cylindrical portion a 25 head direction 26 stator core opening 27 stator core salient pole portion 28 a magnetic disk drive unit 28a magnetic disk drive a 29 magnetic disk mounting side 29a magnetic disk mounting side a 30 mounting screws c 30a mounting screws d

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[Procedure amendment]

[Submission date] April 6, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Having a high permeability to the cylindrical portion of claim 5 wherein said bracket
The magnetic disk drive motor according to claim 1, further comprising a cylindrical shield plate having an opening made of the same material .

6. The motor for a magnetic disk drive according to claim 5, wherein the head direction and the center of the cylindrical shield plate having the opening in the circumferential direction coincide with each other.

7. A magnetic disk drive motor according to claim 1, wherein the matched the stator core opening and the head direction of the stator core.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a brushless motor for driving a disk in which at least one magnetic disk is mounted and driven to rotate in a magnetic disk drive, and more particularly to an inner diameter portion of a hub on which the magnetic disk is mounted. The present invention relates to the structure of an outer rotor type brushless motor (hereinafter referred to as a motor) in which a magnet is fixed to the outer rotor.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

To achieve this object, in a motor of the present invention, a cylindrical shield plate having a cylindrical shape or an opening is arranged in a cylindrical portion of a bracket, and further, an opening of a stator core and a head. It has a configuration in which the directions match.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

[0012] In FIGS. 1 and 2, 19 is highly conductive
A cylindrical shield plate made of a material, such as copper or aluminum , is attached to the cylindrical portion 24 of the bracket 3. The shield plate 19 is made of a conductive material such as aluminum or copper.
Highly efficient material is effective against electromagnetic noise and PWM noise
Is. In addition, the bracket 3 has a point of productivity and economy.
Made of aluminum material by casting process in
Is the majority. In that case, although not shown in the figure,
The shield plate 19 is made of the same material as the cylindrical portion 24 of the bracket 3.
The effect is the same even if they are integrally molded.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

In FIGS. 3 and 4, 1a is a fixed shaft a of the motor, and 12a is a spacer a, which is located between the upper bearing 7 and the lower bearing 8. Reference numeral 2a is a hub a for mounting a magnetic disk, 3a is a bracket a, and a fixed shaft a1a is mounted in the central portion and extends to a magnetic disk mounting side a29a. The bracket a3a is fixed to the magnetic disk drive a28a with a mounting screw d30a. 4a is a cylindrical rotor magnet a fixed to the hub a2a, 5
Reference numeral a denotes a stator core a provided at a position facing the rotor magnet a4a, and is fixed to a lower portion of the fixed shaft a1a. 6a is a winding a wound around the stator core a5a. Reference numeral 9a denotes a stator substrate a, which is attached to the bracket a3a with attachment screws b22, and a position detection element a15a for controlling the excitation of the winding a6a is arranged on the stator substrate a9a. A magnetic fluid seal holder c that holds the upper magnetic fluid seal 11 is fixed to the hub a2a. A magnetic fluid protection plate 20 is attached to the magnetic fluid seal holder c14a. Reference numeral 13a denotes a holder, which is attached to the central portion of the fixed shaft a1a to reduce the radial gap between the holder 13a and the hub a2a and the radial gap between the holder 13a and the lower bearing 8 to reduce grease scattering from the upper bearing 7 and the lower bearing 8. Is being prevented. 10a is a preload spring a
It is located between the lower bearing 8 and the holder 13a, and preloads the upper bearing 7 and the lower bearing 8. 19a is high
It is a cylindrical shield plate a having an opening formed of a material having magnetic permeability, and is a cylindrical portion a24 of the bracket a3a.
It is attached to a with the attachment screw a21, and the shield plate a
The opening 19a is provided on the side opposite to the head direction 25 of the magnetic disk device and has an angle θ1 with respect to the head direction 25.
And the angle θ2 are arranged equally.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018]

The present invention as described above, according to the present invention comprises a cylindrical shield plate with a cylindrical or opening the circular <br/> cylinder portion of the bracket, to further match the head direction and the stator core opening As a result, electromagnetic noise and PWM noise can be reduced, and the magnetic flux leaking from the magnet can be blocked, so that an excellent motor that solves read / write defects can be realized.

Claims (4)

[Claims] 1. A bracket for mounting and fixing to a magnetic disk drive, a fixed shaft fixed to the bracket toward a magnetic disk mounting side, a hub for rotating a magnetic disk, and a rotary shaft for holding the hub. A rotor magnet for generating a rotating force of a bearing supported by the hub and a hub, and a stator core provided to face the rotor magnet and provided with windings, and the bracket includes a cylindrical shield plate. Motor for magnetic disk drive. 2. The motor for a magnetic disk drive according to claim 1, wherein the bracket is provided with a cylindrical shield plate having an opening. 3. A motor for a magnetic disk drive according to claim 2, wherein the center of the head in the circumferential direction of the cylindrical shield plate having the opening is aligned with that of the head. 4. A motor for a magnetic disk drive according to claim 1, wherein the stator core opening is aligned with the head direction.