JPH05242594A - Driving device for magnetic disk type memory device - Google Patents

Abstract

PURPOSE:To reduce the thickness of the driving device. CONSTITUTION:An inner ring 8a of a bearing 8 is circumferentially provided on the outer periphery of a magnet 6 of the driving device 1 provided with a stator coil 4 in a hub 5 and the magnet 6 for driving constituting a rotor 7 and an outer ring 8b of this bearing 6 is fixed to a motor base 3. By that the bearing 8 is circumferentially provided on the outer periphery of the magnet 6, the need for providing the bearings in two stages, upper and lower stages, and, therefore the thickness of the driving device 1 is easily reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device used for driving a magnetic disk or the like.

[0002]

2. Description of the Related Art FIG. 7 is a schematic sectional view of a conventional drive device. This drive device is disclosed by the present applicant in Japanese Patent Application No. 3-93280.
It was proposed in. According to the drive device 100, the two ball bearings 1 are provided above and below the shaft portion 101 in the axial direction.
02 and 103 are installed around these bearings and hub 10.
The stator 105 and the drive magnet 106 were disposed between the stator 4 and the motor 4.

[0003]

However, in recent years, there have been rapid advances in downsizing, thinning, speeding up, large capacity, low power consumption, high impact strength, etc., and conventional drive devices are sufficient to meet these demands. I can't respond.

In a structure in which two bearings are provided above and below a shaft as in a conventional drive device, first of all, the ball bearing itself must be thinned in order to make it thinner, and it is also made thinner. In order to do so, the ball must be made smaller, and if the ball is made smaller, the impact strength becomes weaker. That is, it is difficult to reduce the thickness because two ball bearings are required. Secondly, it was difficult to reduce power consumption due to iron loss between the magnet and the core or between the magnet and the motor base. Therefore, an object of the present invention is to provide a drive device of a magnetic disk type storage device which can be thinned, has high impact resistance, and has low power consumption.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a rotor is arranged outside a stator, and a first bearing is provided around the outer circumference of the rotor. ..

According to the second aspect of the present invention, the second bearing is concentrically provided inside the first bearing, and the stator is provided between these bearings.

According to the invention of claim 3, a ball bearing composed of an inner ring and an outer ring of a magnetic material is used as the first and second bearings, and as a back yoke constituting a magnetic circuit of a drive magnet of the rotor. The inner ring or the outer ring of the ball bearing was used.

According to the invention of claim 4, a low iron loss magnetic material such as a silicon steel plate is attached to the motor base surface facing the axial end surface of the drive magnet.

According to the invention of claim 5, a magnetic material is attached to the end surface of the drive magnet facing the motor base surface.

[0010]

According to the invention of claim 1, the outer circumference of the rotor is the first
It is supported by the bearing of and rotates.

According to the second aspect of the present invention, the rotor is rotated by being supported by the two concentric bearings.

According to the third aspect of the invention, the two bearings are ball bearings, and the inner ring or the outer ring serves as a back yoke.

According to the fourth or fifth aspect of the invention, the iron loss due to the rotation of the rotor is improved.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a schematic cross-sectional view of a first embodiment of a drive device for a magnetic disk type storage device according to the present invention, FIG.
Is an enlarged view of the first bearing portion of the first embodiment, FIG. 3 is a schematic sectional view of the second embodiment, FIG. 4 is a schematic sectional view of the third embodiment, and FIG. 5 is a fourth embodiment. FIG. 6 is a schematic sectional view of the fifth embodiment. In the present embodiment, the case of a fixed disk device (hereinafter referred to as a hard disk) will be described as an example, but the present invention is not limited to this hard disk and may be used for another magnetic disk device. Further, the same components are designated by the same reference numerals, and the description thereof will be omitted.

First, the first embodiment will be described. The first embodiment corresponds to the inventions of claims 1, 3, 4 and 5. In FIG. 1, a drive device 1 has a stator coil 4 arranged on an upper surface of a motor base 3 forming a bottom surface of a substantially box-shaped case 2, and a hub 5 and a magnet 6 arranged so as to cover the stator coil 4. A part of the hub 5 located on the upper surface of the stator coil 4 and the magnet 6 form a rotor 7. Further, a first bearing 8 corresponding to a first bearing is provided on the outer side surface 6a of the magnet 6.
An inner ring 8a of the hub 5 is provided, and an extension portion 5b of a part 5a of the hub 5 is formed so as to cover the first bearing 8.
The hub 5 for mounting the hard disk 9 is formed by the part 5a of the hub 5 and the extending portion 5b, and the disk 9 is pressed and supported by the clamper 10. The outer ring 8b of the bearing 8 is fixed to the motor base 3.

With this structure, the hub 5, the magnet 6, and the inner ring 8a of the bearing rotate together through the balls 8c, and the disk 9 mounted on the hub 5 rotates.

By arranging the bearings outside the motor in this way, it is possible to use a single ball bearing. Therefore, compared with the conventional magnetic disk storage device, the thickness can be approximately halved, and since only one ball bearing is required, the ball diameter can be increased and the number of balls can be increased, resulting in high durability. It is possible to provide a shock-resistant magnetic disk storage device. Note that the bearing is not a ball bearing but may be, for example, an SGB (Spira, not shown).
l Groove Bearing) may be used.

Further, by fixing the outer ring 8b of the ball bearing to the motor base 3 and surrounding the magnet 6 around the inner ring 8a, a preload can be applied to the ball bearing by the attraction force in the axial direction of the magnet.

Further, the radial clearance of the ball bearing (Δ
If r) is configured so that Δr ≦ 0, fluctuations in the radial direction (direction perpendicular to the axis) can be reduced, and preloading by a spring or the like as in the conventional example becomes unnecessary. In other words, one ball bearing can be used in a preloaded state.

Further, as shown in FIG. 2, the ball bearing 8, the motor base 3, and the hub 5 are made of a material having substantially the same linear expansion coefficient, and the ball bearing outer ring 8b is made up of the motor base 3.
It is fixed by press fitting or adhesion to the ball bearing inner ring 8
a, the driving magnet 6 and the hub 5 are configured to rotate as a unit, and the axial gap g1 between the bearing outer ring 8b and the part 5b of the hub 5 that extends further outward than the ball bearing outer ring 8b, the same radial direction. The gap g
2 or the axial gap g3 between the hub 5 and the motor base 3
It is also possible to make the grease of the ball bearing 8 not to scatter by making at least one of the gaps as narrow as possible.

Next, a second embodiment will be described. The second embodiment corresponds to the invention of claims 2 and 3. In FIG. 2, the drive device 20 concentrically arranges the first bearing 8 and the second bearing 22 with the stator coil 21 interposed therebetween. Further, the magnet 6 is provided around the inner ring 8a of the first bearing 8 and the outer ring 22b of the second bearing 22 is provided.
A magnet 23 is provided around the magnets 6, 6, and
3, the stator coil 21 faces each other with a constant gap.

With this structure, the hub 24, the magnets 6,
23, and the inner ring 8a and the outer ring 22b of the bearing integrally rotate via the balls 8c and 22c, and rotate the disk 9 mounted on the hub 24. The outer ring 8b and the inner ring 22a of the bearing are fixed to the motor base 25.

Thus, by arranging two ball bearings concentrically, and arranging a stator and a magnet between these bearings, and especially using an air-core coil as a stator coil, a coreless structure is obtained, and therefore iron loss is caused. Less, low power consumption, high speed (high speed rotation)
It is possible to provide a magnetic disk type storage device that is thin and has high impact resistance as in the first embodiment.

Next, a third embodiment will be described. The third embodiment corresponds to the invention of claims 2 and 3. The drive unit 30 of FIG. 3 is one in which the stator coil 21 and the magnets 6, 23 of the drive unit 20 are arranged in two stages in the axial direction. That is, the first bearing 8 and the second bearing 22 are concentrically arranged with the stator coil 31 interposed therebetween. Further, a magnet 32 is provided between the inner ring 8a of the first bearing 8 and the outer ring 22b of the second bearing 22, and the stator coil 31 faces the magnet 32 with a certain gap. Meanwhile, the magnet 32 is fixed to the hub 33, and the stator coil 31 is fixed to the motor base 34.

With this configuration, the hub 33 and the magnet 3
2, and the inner ring 8a and outer ring 22b of the bearing are balls 8.
The disk 9 mounted on the hub 33 is rotated by rotating integrally with the c and 22c. The outer ring 8b and the inner ring 22a of the bearing are fixed to the motor base 34.

The third embodiment is an example in which the positional relationship between the stator coil and the magnet in the second embodiment is a plane facing type. Also, in the second embodiment, the magnets 6, 2
3, the bearings 8 and 22 and the stator coil 21 are removed.
The invention corresponding to claim 3 is achieved by making the and the close to each other and configuring the bearings 8 and 22 with a magnetic material.

Next, a fourth embodiment will be described. The fourth embodiment corresponds to the invention of claim 4. Drive device 40 of FIG.
Is a low iron loss magnetic material attached to the upper surface of the motor base 3 of the drive unit 1. That is, in the driving device 40, the stator coil 4, the driving magnet 6,
And the axial end faces 4a, 6 of the ball bearing 8
Motor base 3 so as to have a constant gap with b and 8d
A low iron loss magnetic material 41 of silicon steel plate was attached to the upper surface of the.
The material is not limited to the silicon steel sheet, and other materials may be used as long as they are low iron loss materials.

Since the gap between the magnet and the motor base becomes narrower due to the thinner type, the eddy current loss and the iron loss due to the hysteresis loss increase. In the fourth embodiment, in order to reduce the iron loss, a low iron loss material such as a silicon steel plate is integrally or separately attached to the motor base to reduce the power consumption.

Next, a fifth embodiment will be described. The fifth embodiment corresponds to the invention of claim 5. Drive device 50 of FIG.
Is a magnetic material attached to the end face of the drive magnet 6 facing the motor base 3 of the drive device 1. That is, in the drive device 50, the motor base 3
A stainless steel plate 51 made of a magnetic material was attached to the end surface 6b of the magnet 6 so as to have a constant gap with the surface of the. The magnetic material is not limited to the stainless steel plate 51, and another magnetic material may be used. Like the fourth embodiment, the fifth embodiment also has a magnetic material attached to the end surface of the magnet facing the motor base in order to reduce iron loss.

[0030]

By arranging the bearing outside the rotor and the stator, the bearing can be constructed in a single stage.
Further, since the two bearings can be arranged concentrically, vibrations and the like due to the rotation of the motor can be reduced.
Further, iron loss can be reduced by attaching the magnetic material to the motor base surface or the magnet end surface.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a first embodiment of a drive device for a magnetic disk type storage device according to the present invention.

FIG. 2 is an enlarged view of a first bearing portion of the first embodiment.

FIG. 3 is a schematic sectional view of the second embodiment.

FIG. 4 is a schematic sectional view of the third embodiment.

FIG. 5 is a schematic sectional view of the fourth embodiment.

FIG. 6 is a schematic sectional view of the fifth embodiment.

FIG. 7 is a schematic cross-sectional view of a conventional drive device.

[Explanation of symbols]

1, 20, 30, 40, 50 ... Driving device, 4, 21, 3
1, ... Stator coil, 5,24,33 ... Hub, 6,2
3 ... Magnet, 7 ... Rotor, 8 ... 1st bearing (1st bearing), 22 ... 2nd bearing (2nd bearing).

Claims (5)

[Claims] 1. A drive device for a magnetic disk type storage device comprising a stator and a rotor provided in a hub, and an in-hub type motor in which rotation of the rotor and rotation of the hub are interlocked with each other. A drive device for a magnetic disk type storage device, wherein the drive device is provided and a first bearing is provided around the outer periphery of the rotor. 2. The magnetic disk type storage device according to claim 1, wherein a second bearing is concentrically provided inside the first bearing, and the stator is disposed between the bearings. Drive. 3. A ball bearing composed of a magnetic inner ring and an outer ring is used as the first and second bearings, and an inner ring or an outer ring of the ball bearing is used as a back yoke constituting a magnetic circuit of a drive magnet of the rotor. 3. The drive device for a magnetic disk type storage device according to claim 1, wherein: 4. The low iron loss magnetic material such as a silicon steel plate is attached to the motor base surface facing the axial end surface of the drive magnet. Drive device for magnetic disk type storage device. 5. The drive device for a magnetic disk type storage device according to claim 1, wherein a magnetic material is attached to an end surface of the drive magnet facing the motor base surface.