JP2000253632A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor which is suitable for the rotation drive of a small magnetic disk and can restrain leakage of magnetic flux from a rotor magnet. SOLUTION: This spindle motor is equipped with a base member 2, a rotor hub 4 rotatably retained by the base member 2 via ball bearings 24, 26, a rotor magnet 42 installed on the rotor hub 4, and a stator 46 which faces the rotor magnet 46 and is arranged outside the radial direction. The rotor hub 4 has a hub main body 16 on which a disk mounting part 38 mounting a magnetic disk 14, and a drooping part 40 stretching from the disk mounting part 38 toward the base member 2. The rotor magnet 42 is installed in the drooping part 40. A magnetic shielding member 44 is interposed between the disk mounting part 38 and the rotor magnet 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a spindle motor for rotating a magnetic disk such as a hard disk.

[0002]

2. Description of the Related Art As a spindle motor for rotating a magnetic disk such as a hard disk having a relatively small outer diameter, an inner rotor type motor, for example, Japanese Patent Application Laid-Open No.
The one disclosed in 316703 is known.
This known spindle motor includes a bracket as a stationary member, a bearing sleeve rotatably supported on the bracket via a pair of ball bearings, a rotor hub mounted on the bearing sleeve, and a rotor mounted on the bearing sleeve. The magnet includes a magnet and a stator mounted on a bracket so as to face the rotor magnet. The rotor hub includes a cylindrical hub main body, and a disk mounting portion is provided at a lower end portion of the hub main body, and the magnetic disk is mounted on the disk mounting portion.

[0003]

However, in such a spindle motor, an annular accommodating space is formed between the bearing sleeve and the hub body of the rotor hub, and the accommodating space includes a rotor magnet and a magnetic circuit constituting a magnetic circuit. The stator is housed. Therefore, depending on the size of the magnetic disk mounted on the hub body, the size of the hub body,
In other words, the size of the space accommodating the magnetic circuit is limited. In recent years, hard disk drive devices have tended to be smaller and thinner. However, when a small magnetic disk, for example, a disk having an outer diameter of about 1 inch, is driven to rotate by a spindle motor having such a configuration, a magnetic circuit is required. Because of the small size, it is not possible to obtain a sufficient rotational torque, and it is not possible to sufficiently cope with recent demands for downsizing and thinning.
In addition, when the spindle motor is reduced in size and thickness, when incorporated in a hard disk drive, the distance between the magnetic head for writing and / or reading information on the magnetic disk and the rotor magnet of the spindle motor also becomes smaller, and the distance from the rotor magnet is reduced. Magnetic flux leakage becomes a problem.

An object of the present invention is to provide a spindle motor suitable for driving a magnetic disk having a small outer diameter to rotate. Another object of the present invention is to provide a spindle motor capable of suppressing leakage of magnetic flux from a rotor magnet.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a stationary member,
A spindle motor comprising: a rotor hub rotatably supported by the stationary member via bearing means; a rotor magnet mounted on the rotor hub; and a stator disposed radially outward facing the rotor magnet. The rotor hub has a hub main body, and the hub main body is provided with a disk mounting portion on which a magnetic disk is mounted, and a hanging portion further extending from the disk mounting portion toward the stationary member. The rotor magnet is mounted on an outer peripheral surface of the hanging portion of the rotor body, and a magnetic shield member is interposed between the disk mounting portion of the rotor body and the rotor magnet. And

According to the present invention, the rotor body of the rotor hub is provided with a disk mounting portion and a hanging portion extending from the disk mounting portion, a rotor magnet is mounted on an outer peripheral surface of the hanging portion, and a stator is mounted on the rotor magnet. It is disposed radially outwardly opposite. Therefore, the rotor magnet and the stator constituting the magnetic circuit of the motor are arranged radially outside the rotor hub, and the space for this magnetic circuit is not substantially restricted by the size of the magnetic disk mounted on the hub body, Even when a magnetic disk having a small outer diameter is mounted, a sufficient space can be secured, and a large rotating drive torque can be obtained even with a small disk. Also,
Since the magnetic shield member is interposed between the disk mounting portion of the rotor body and the rotor magnet mounted under the hanging portion, the magnetic flux from the rotor magnet to the magnetic disk mounted on the disk mounting portion is reduced. There is almost no leakage, and it is possible to prevent the rotor magnet from adversely affecting the magnetic disk and the magnetic head.

Further, according to the present invention, the stationary member is provided with a supporting sleeve wall, the rotor hub is provided with a rotating shaft portion, and the rotating shaft portion is rotatable on the supporting sleeve wall via the bearing means. It is characterized by being supported by.

According to the present invention, the rotor hub is provided with a rotating shaft portion, and the rotating shaft portion is rotatably supported by the support sleeve portion via the bearing means, so that it can be provided as a shaft rotating type motor. In this connection, the thickness of the motor can be reduced.

In the present invention, the stationary member is provided with a housing recess, the stator is mounted on an outer peripheral surface of the housing recess, and the rotor magnet and the stator are housed in the housing recess. An outer magnetic shield member is attached to the stationary member so as to cover the stator, and the magnetic shield member and the outer magnetic shield member are disposed so as to cover an upper opening of the housing recess. And

According to the present invention, the stationary member is provided with the housing recess, and the rotor magnet and the stator are provided in the housing recess, so that the motor can be further thinned. Also, since the magnetic shield member and the outer magnetic shield member cover the upper opening of the housing recess, the leakage of magnetic flux from the rotor magnet and the stator is suppressed,
An adverse effect on the magnetic disk and the magnetic head due to the leakage magnetic flux can be prevented. Further, according to the present invention, the outer diameter of the magnetic disk mounted on the disk mounting portion of the rotor body is 1 inch.

According to the present invention, it is possible to provide a motor for rotating a magnetic disk having an outer diameter of 1 inch.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle motor according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing one embodiment of a spindle motor according to the present invention.

Referring to FIG. 1, the illustrated spindle motor includes a base member 2 as a stationary member, and a rotor hub 4 rotatable with respect to the base member 2. In this embodiment, the base member 2 also functions as a base member of a magnetic disk drive such as a hard disk drive. Instead of such a configuration, the stationary member may be formed of a bracket, and the bracket may be attached to the base member of the magnetic disk drive.

The base member 2 has an annular bottom wall 6, and a circular opening is formed in the center of the annular bottom wall 6. A support sleeve wall 8 is provided on an inner peripheral portion of the annular bottom wall 6 that defines the circular opening.
Extending substantially vertically upward from A supporting peripheral wall 10 is provided on an outer peripheral portion of the annular bottom wall portion 6.
A base body wall 12 is provided at an upper end portion of the base body wall to extend radially outward. In this embodiment, the annular bottom wall portion 6, the support sleeve wall 8, the support peripheral wall 10, and the base body wall 12 are integrally formed, and are formed of, for example, aluminum or an aluminum alloy. Instead of the above-described configuration, for example, the support sleeve wall 8 may be formed separately, and the support sleeve wall 8 may be fixed to the annular bottom wall 6 of the base member 2.

The rotor hub 4 has a hub body 16 on which a magnetic disk 14 such as a hard disk is mounted. The hub body 16 has a cylindrical peripheral side wall 18 and an end wall 20 provided at one end of the peripheral side wall 18, and a rotation shaft portion extending toward the stationary member 2 is provided at a central portion of the end wall 20. 2
2 are provided. In this embodiment, the rotating shaft portion 22 is provided integrally with the hub body 16, but the hub body 16
Alternatively, it may be formed separately and fixed to this.

The rotary shaft portion 22 of the rotor hub 4 is rotatably supported on the support sleeve wall 8 of the base member 2 via bearing means. The bearing means includes a pair of ball bearings 2 arranged at intervals in the axial direction (the vertical direction in FIG. 1).
The outer races 28 and 30 of the ball bearings 24 and 26 are mounted on the inner peripheral surface of the support sleeve wall 8, and the inner races 32 and 34 are mounted on the outer peripheral surface of the rotating shaft portion 22 of the hub body 16. The outer ring 2 of these ball bearings 24, 26
An annular spacer 36 is interposed between 8 and 30.

At the lower end of the peripheral side wall 18 of the hub body 4, there is provided an annular disk mounting portion 38 projecting outward in the radial direction. The hub body 16 has a hanging part 4 extending downward from the disk mounting part 22 toward the stationary member 2.
0, the inner diameter of the hanging portion 40 is substantially equal to the inner diameter of the peripheral side wall 18 of the hub body 4, and the outer diameter thereof is substantially equal to the outer diameter of the peripheral side wall 18. At the radially outer side of the supporting sleeve wall 8
It extends downward following 8. In this embodiment, the disk mounting portion 38 and the hanging portion 40 are also formed integrally with the hub main body 16, and are formed of, for example, aluminum, aluminum alloy, iron, stainless steel, or the like.

This spindle motor is an inner rotor type motor. An annular rotor magnet 42 is mounted on an outer peripheral surface of a hanging portion 40 of the rotor hub 4. An upper end surface of the rotor magnet 42 and a disk mounting portion of the hub body 16 are mounted. And a lower surface of the ring-shaped magnetic shield member 44.
Is interposed. The magnetic shield member 44 is formed of a magnetic material such as iron, and functions as a magnetic shield when the hub body 16 is formed of a magnetic member such as iron, but is formed of a nonmagnetic material such as aluminum. Functions as a back yoke of the rotor magnet 42 in addition to the magnetic shield.

A stator 46 is disposed on the outside in the radial direction so as to face the rotor magnet 42. The stator 46 has a stator core 48 formed by stacking core plates, and the outer peripheral portion of the stator core 48 is mounted on the inner peripheral surface of the supporting peripheral wall 10 of the base member 2. The stator core 48 is provided with a plurality of teeth at intervals in the circumferential direction. The teeth extend radially inward toward the rotor magnet 42, and a coil 50 is wound around the teeth as required. Has been.

A ring-shaped outer magnetic shield member 52 is mounted on the inner peripheral portion of the base body wall 12 of the base member 2. The outer magnetic shield member 52 is formed of a plate-like member formed of a magnetic material such as iron, and has an outer peripheral portion attached to the inner surface of the base main body wall 12.
The inner peripheral side of the outer magnetic shield member 52 extends radially inward toward the rotor hub 4, and covers the upper part of the stator 46 to prevent leakage of magnetic flux from the stator 46.

A cap member 54 is mounted on the opening of the bottom wall 6 of the base member 2.
This seals one end (the lower end in FIG. 1) of the support sleeve wall 8.

In such a spindle motor, a drive current is supplied to the coil 50 of the stator 46 as required. When the driving current is supplied, the stator core 48 is excited, and the rotor hub 16 is driven to rotate in a predetermined direction by the mutual magnetic action between the stator core 48 and the rotor magnet 42, so that the magnetic disk 14 mounted thereon also rotates integrally.

The above-described spindle motor has the following features. First, a hanging portion 40 extending downward from the disk mounting portion 38 is provided on the hub body 16, and a rotor magnet 42 is mounted on the outer peripheral surface of the hanging portion 40.
A stator 4 is provided radially outside the rotor magnet 42.
6, a magnetic circuit for rotationally driving the motor is disposed outside the rotor body 16 in the radial direction. Therefore, the magnetic circuit can be designed without being largely affected by the size of the magnetic disk 14 mounted on the rotor hub 4, and a large rotational driving torque can be obtained even with a small motor. In recent years, there has been a trend toward miniaturization in the field of hard disk drives,
4 has a smaller outer diameter, and such a configuration is advantageously applied to a magnetic disk 14 having an outer diameter of 2.5 inches or less, particularly a spindle motor for rotating a magnetic disk 14 having an outer diameter of 1 inch. Can be.

The disk mounting portion 38 of the rotor hub 4
A magnetic shield member 44 is interposed between the rotor magnet 42 and the rotor magnet 42 mounted on the hanging portion 40. Therefore, the leakage of the magnetic flux upward from the rotor magnet 42 is suppressed, and the adverse effect of the leakage magnetic flux on the magnetic disk 14 and the magnetic head (a head for writing and / or reading information on the magnetic disk 14) is avoided. Can be.
In addition, with this configuration, the number of components arranged in the radial direction of the motor can be reduced, and downsizing of the rotor hub 4 can be achieved. As shown in FIG. 1, it is desirable that the outer peripheral portion of the magnetic shield member 44 protrude somewhat outward in the radial direction beyond the outer peripheral end of the rotor magnet 42. Leakage of magnetic flux from 42 can be further suppressed.

The annular bottom wall 6, the support sleeve wall 8 and the support peripheral wall 10 of the base member 2 form an annular accommodation recess 5.
6 is formed, and substantially the entire rotor magnet 42 and the stator 46 are housed in the annular housing recess 56. By accommodating in this manner, the height from the lower surface of the annular bottom wall portion 6 of the base member 2 to the upper surface of the end wall 20 of the rotor hub 4, that is, the overall height of the motor can be reduced.
A thin motor can be achieved. In this spindle motor, a rotary shaft portion 22 is further provided on the rotor hub 4, and the rotary shaft portion 22 is supported by the support sleeve wall 8 of the base member 2 via bearing means, and a distal end portion of the rotary shaft portion 22 is supported. Since it extends to the vicinity of the cap member 54 attached to the one end opening of the sleeve wall 10, the motor can be further thinned while ensuring the axial distance between the pair of ball bearings 24, 26. .

Further, an outer magnetic shield member 52 is mounted on the base member 2, and the upper opening of the annular receiving recess 56 is covered by the outer magnetic shield member 52 and the magnetic shield member 44 mounted on the rotor hub 4. Leakage of magnetic flux upward from the magnet 42 and the stator 48 can be suppressed, and adverse effects on the magnetic disk 14 and the magnetic head due to the magnetic flux can be avoided. The outer magnetic shield member 52 is disposed so as to define a surface substantially the same as the magnetic shield member 44 mounted on the rotor hub 4, and its inner peripheral portion is directed toward the outer peripheral portion of the magnetic shield member 44. It is desirable that the magnetic shield member 44 and the magnetic shield member 44, 52 have such a small size that the gap between the two magnetic shield members 44 and 52 can be reduced, so that the leakage of magnetic flux through the gap can be further reduced.

The embodiment of the spindle motor according to the present invention has been described above. However, the present invention is not limited to such an embodiment, and various changes and modifications can be made without departing from the scope of the present invention. is there.

For example, in the illustrated embodiment, a description has been given by applying the present invention to a shaft rotation type motor in which a hub is provided with a rotating shaft and the rotating shaft is rotatably supported via bearing means. Without being limited to this, the present invention can be similarly applied to a fixed shaft type motor in which a stationary shaft portion is provided on a base member and a rotor hub is rotatably supported on the stationary shaft portion via bearing means.

[0029]

According to the spindle motor of the first aspect of the present invention, the rotor magnet and the stator constituting the magnetic circuit of the motor are arranged radially outside the rotor hub, so that the magnet is small even if the motor is downsized. A sufficient space for the circuit can be secured, and a large rotational driving torque can be obtained. Further, since the magnetic shield member is interposed between the disk mounting portion of the rotor main body and the rotor magnet, it is possible to suppress leakage of magnetic flux from the rotor magnet.

According to the spindle motor of the second aspect of the present invention, it can be provided as a shaft rotation type motor, and the motor can be made thinner.

Further, according to the spindle motor of the third aspect of the present invention, since the rotor magnet and the stator are arranged in the recessed portion of the stationary member, the motor can be further thinned. In addition, since the magnetic shield member and the outer magnetic shield member cover the upper opening of the housing recess, leakage of magnetic flux from the rotor magnet and the stator can be suppressed. Further, according to the spindle motor of the fourth aspect of the present invention, the spindle motor can be provided as a motor for rotationally driving a magnetic disk having an outer diameter of 1 inch.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a spindle motor according to the present invention.

[Explanation of symbols]

 2 Base Member 4 Rotor Hub 8 Support Sleeve Wall 16 Hub Body 22 Rotating Shaft 24, 26 Ball Bearing 38 Disk Placement 40 Hanging Part 42 Rotor Magnet 44 Magnetic Shield Member 46 Stator 52 Outer Magnetic Shield Member 56 Annular Containing Depression

Claims (4)

[Claims] A stationary member, a rotor hub rotatably supported by the stationary member via bearing means, a rotor magnet mounted on the rotor hub, and a radially outer surface facing the rotor magnet. The rotor hub has a hub main body, and the hub main body further includes a disk mounting portion on which a magnetic disk is mounted, and the disk mounting portion further extends from the disk mounting portion toward the stationary member. An extended hanging portion, wherein the rotor magnet is mounted on an outer peripheral surface of the hanging portion of the rotor body, and a magnetic shield is provided between the disk mounting portion of the rotor body and the rotor magnet. A spindle motor having a member interposed. 2. The stationary member is provided with a supporting sleeve wall, the rotor hub is provided with a rotating shaft portion, and the rotating shaft portion is rotatably supported by the supporting sleeve wall via the bearing means. The spindle motor according to claim 1, wherein 3. The stationary member is provided with an accommodation recess,
The stator is mounted on an outer peripheral surface of the housing recess, the rotor magnet and the stator are housed in the housing recess, and an outer magnetic shield member is mounted on the stationary member so as to cover the stator. 3. The spindle motor according to claim 1, wherein the magnetic shield member and the outer magnetic shield member are disposed so as to cover an upper opening of the housing recess. 4. The spindle motor according to claim 1, wherein an outer diameter of the magnetic disk mounted on the disk mounting portion of the rotor body is 1 inch.