JPH06335216A - Spindle motor for disk - Google Patents

Abstract

PURPOSE:To provide a spindle motor for a disk in which resonance sound, noise generated by an electromagnetic vibration is prevented and quietness is high. CONSTITUTION:A vibration is shut OFF by providing a small air gap between a central circular hole of a stator and a stationary shaft by using a cylindrical stepped holder 15 to fix the central circular hole of a stator core 18 and the shaft 13 to prevent noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration and noise prevention structure for a disk drive motor.

[0002]

2. Description of the Related Art The recent trend of magnetic disk drive devices is toward the development of higher capacity magnetic disk drive devices, and therefore more disk-shaped magnetic disks are stacked in a limited height and volume. For this reason, the main disk drive motor is an in-hub type motor housed in a disk drive hub, and since the number of magnetic disks is large, there are many methods for directly fixing the motor shaft to the drive chassis. There is.

A conventional spindle motor will be described below. FIG. 5 is a structural sectional view of a conventional disk spindle motor.

In FIG. 5, 13 is a fixed shaft and 14 is a fixed shaft.
Is a hole which is opened substantially in the center of the fixed shaft 13 and is connected to the lower side, and is a passage for guiding the lead wire to the outside of the motor in order to electrically connect the signal of the hall sensor 17 and the winding 19 of the motor. . Reference numeral 16 denotes a disk-shaped printed wiring board for wiring the hall sensor 17, which is attached to the cylindrical stepped holder 15 and adhered to the fixed shaft 13. Reference numeral 18 denotes a laminated stator core, which is bonded and fixed to the fixed shaft 13 through a central circular hole.

Reference numeral 10 denotes a hub that supports the inner diameter of the disk on its outer peripheral cylindrical portion and is made by cutting an aluminum alloy. 1
Reference numeral 2 is a cylindrical magnet, and an iron cylindrical rotor yoke 11 is adhered and fixed to the outer circumference thereof. Reference numeral 27 is a hollow ring made of aluminum or iron, the outer peripheral portion of which is bonded to the hub 10 and the inner peripheral portion of which is accurately bonded to the bearing 22 with a slight interference fit. Reference numeral 21 denotes the other bearing, which is adhered to the upper end of the hub 10 by an interference fit. Reference numeral 25 is a disc spring for biasing the bearings 21 and 22 with an appropriate preload, and is fixed by a ring washer 26.

23 and 24 are ball bearings 21 and 22.
This is a magnetic fluid seal that prevents the grease splashes generated from being discharged to the outside of the motor. Although not shown in the figure, the magnetic fluid is injected into the clearance with the shaft to perform its function. The spindle motor assembled with the above-described structure has the magnet 12, which constitutes the rotor portion around the fixed shaft 13,
The rotor yoke 11, the hub 10, and the hollow ring 27 are rotatable via upper and lower bearings 21 and 22.

The operation of the spindle motor configured as described above will be described below. 32 is a stator having 6 slots and is wound so as to form a three-phase motor. The magnet 12 is magnetized in its inner surface to have four or eight poles in the circumferential direction. Hall sensor 17 is stator 3
It is accurately positioned in 2, and three are arranged at an equal angle. The Hall sensor 17 reacts to the magnetism of the magnet 12 and sequentially switches the current to each phase of the motor winding 19 to generate attraction and repulsion between the magnet 12 and the stator 32, and the rotor 33 rotates. .

[0008]

Since this spindle motor has a high rotation speed of 3600 to 6000 rotations per minute, the switching speed of the current to each phase is high, and the electromagnetic vibration generated from the winding wire 19 has a large energy. Has become. The electromagnetic vibration is transmitted from the stator core 18 to the fixed shaft 13,
Further, although not shown in FIG. 5, there is a problem that it is transmitted to the magnetic disk drive chassis and becomes a resonance sound or noise.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a disk spindle motor having high quietness.

[0010]

In order to achieve this object, a disk spindle motor of the present invention has a first circular hole as a center hole of a stator and a first circular hole which is concentric with the first circular hole and has a first diameter. Has a second circular hole that is larger than the circular hole, and a cylindrical step holder made of aluminum alloy that is fixed to the second circular hole, and a fixed shaft is bonded to the inner peripheral surface of the cylindrical step holder. It is fixed and a slight air gap is provided between the inner peripheral surface of the first circular hole and the fixed shaft, or the diameter of the part of the fixed shaft that abuts the stator central hole is made thin to provide an elastic adhesive. It is configured such that the fixed shaft and the stator are filled and adhered.

[0011]

With this configuration, electromagnetic vibrations generated from the stator can be transmitted by a slight air gap provided between the first circular hole of the aluminum alloy cylindrical step holder and the fixed shaft in the first configuration. Is prevented, and therefore transmission to the magnetic disk drive chassis is greatly reduced. Further, in the second configuration, since electromagnetic vibration is absorbed by the elastic adhesive, it does not leak to the outside through the fixed shaft.

[0012]

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

FIG. 1 is a sectional view of a spindle motor incorporated in a box of a magnetic disk drive device. In the figure, 44 is the bottom of the box of the drive device, and 45 is the top surface of the box.
The box is made of aluminum die-cast, the upper end surface of the motor fixed shaft 13 is fixed by a screw 46, and the lower end of the fixed shaft 13 is fixed to the bottom 44 of the box by adhesive pressing. Reference numeral 40 is a magnetic disk, 41 is a cylindrical spacer made of aluminum for stacking the magnetic disks at equal intervals, 42 is a magnetic disk clamper, which sandwiches the disk with the flange 31 of the hub 10 and is fixed to the hub 10 with a screw 43. In FIG. 1, up to five discs are shown, but discs in the middle are omitted.

Reference numeral 10 denotes a cylindrical hub for supporting a disk on the outer peripheral portion, 11 a rotor yoke, 12 an inner peripherally magnetized cylindrical magnet, 27 a hollow ring made of aluminum or iron, and the outer peripheral portion of the hub 10. , The inner circumference is bearing 2
It is bonded to 2 with high precision and a slight interference fit.
Reference numeral 21 denotes the other bearing, which is adhered to the upper opening of the hub 10 by an interference fit. Reference numeral 25 is a disc spring for biasing the bearings 21 and 22 with an appropriate preload, and is fixed by a ring washer 26. 23
And 24 are magnetic fluid seals for preventing the bearing grease from scattering.

18 is a laminated silicon steel plate (stator core), 19 is a winding wound on the stator core 18,
Reference numeral 17 is a hall sensor, which is not shown in the drawing but is equally spaced.
Individually arranged. Reference numeral 16 is a printed wiring board for connecting the wiring of the hall sensor 17 and the winding 18, and 14 is a hole formed in the fixed shaft, and is a hole for drawing out a lead wire from the printed wiring board 16 to the outside of the motor below the fixed shaft 13.

Reference numeral 15 is a cylindrical stepped holder, in which the stator 32 is press-fitted and held in the first step on the outer periphery, and the printed wiring board 16 is held in the second step by adhesion or the like. In addition, the inner peripheral surface of the cylindrical stepped holder 15 is used for adhesive fixing to the fixed shaft, and the center hole of the stator core 18 and the fixed shaft 13 do not directly contact with each other, but the air gap 20 is assembled. . FIG. 2 is an enlarged view of a main part of this assembly structure. In the figure, reference numeral 18a is powder coating for insulation applied to the surface of the stator core. The first circular hole of the central hole of the stator 32 has a hole diameter A, the second circular hole has a hole diameter B, and the inner diameter of the cylindrical stepped holder 15 is C. In FIG. 2, the hole diameters are larger in the order of B, A, and C, and the fixed shaft 1 has an inner diameter C.
3, and the hole diameter A is made slightly larger than the inner diameter C to form an air gap 20 with the fixed shaft 13.

(Second Embodiment) FIG. 3 shows a structure different from that of the first embodiment. In this case, the first circular hole of the stator 32,
The inner diameters of the cylindrical stepped holders 15 are substantially the same, and the stator 3 is provided on the outer peripheral portion of the first step of the cylindrical stepped holder 15.
Press in 2. Then, the inner peripheral surface of the cylindrical stepped holder 15 is bonded to the fixed shaft 13 with an adhesive. Regarding the axial portion of the fixed shaft 13 that abuts on the central hole of the stator 32,
A recess 28 is formed on the entire circumference to form an escape from the inner circumference of the central hole of the stator 32, and a slight air gap 20 is formed. In this case, there is an advantage that the inclination when the stator 32 is attached to the fixed shaft 13 can be minimized.

The operation of the spindle motor configured as described above will be described below. First, the electromagnetic vibration generated from the winding wire 19 when rotating at a high speed also vibrates the stator core 18. A part of the vibration energy is transmitted to the fixed shaft 13 via the cylindrical stepped holder 15, but as shown in the air gap 20 of FIG. 1 and the air gap 20 of FIG. The vibration energy is prevented from being transmitted, and as a result, the spindle motor for the disk becomes a highly quiet motor.

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

FIG. 4 shows a third embodiment, and since the names of each part are the same as those in FIGS. 1 and 5, detailed description thereof will be omitted. Reference numeral 15 is a cylindrical stepped holder, which holds only the printed wiring board 16 on its outer peripheral portion. Further, the central hole of the stator core 18 is formed with the same diameter in the axial direction. A recess 28 is formed on the entire circumference of most of the portion of the fixed shaft 13 that penetrates the stator core 18. Reference numeral 29 is an elastic adhesive filled in the gap between the recess 28 and the central hole of the stator core. This elastic adhesive is, for example, "Cemedine Super X" manufactured by Cemedine.
Etc. can be used. That is, the adhesive has elasticity even after curing.

By using the elastic adhesive as an adhesive between the recess 28 of the fixed shaft 13 and the stator core 18 as described above, electromagnetic vibration from the stator is absorbed and blocked by the elastic adhesive, and the operation is quiet. A spindle motor can be obtained.

[0022]

As described above, according to the present invention, as a means for attaching the stator core to the fixed shaft, a cylindrical stepped holder is used to hold only a part of the stator core, or an elastic adhesive is used to cause vibration and noise. It is possible to obtain a quiet spindle motor with less power consumption. The subassembly shown in FIG. 2 is
Since the printed wiring board is integrated with the stator, there is also an advantage that the accuracy of Hall sensor mounting, defective soldering, defective wiring of windings, etc. can be easily determined by electrical inspection.

[Brief description of drawings]

FIG. 1 is a sectional view of mounting a disk of a disk spindle motor to which a drive prevention structure according to a first embodiment of the present invention is applied and mounting the motor on a drive device.

FIG. 2 is an enlarged view of a main part in the first embodiment of the present invention.

FIG. 3 is an enlarged view of a main part in the second embodiment of the present invention.

FIG. 4 is a sectional view of a motor according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a conventional disk spindle motor.

[Explanation of symbols]

 10 hub 11 rotor yoke 12 magnet 13 fixed shaft 14 hole 15 cylindrical stepped holder 16 printed wiring board 17 hall sensor 18 stator core 19 winding 20 air gap 21, 22 bearing 23, 24 magnetic fluid seal 25 disc spring 26 ring washer 27 hollow Ring 29 Elastic adhesive 31 Collar 32 Stator 33 Rotor 40 Magnetic disk 41 Cylindrical spacer 42 Magnetic disk clamper 43, 46 Screws 44 Bottom of drive unit box 45 Top surface of drive unit box

Claims (3)

[Claims] 1. A stator core is axially stacked,
A stator around which the winding is wound, a cylindrical magnet surrounding the air gap in the radial direction, a rotor yoke, a rotor composed of a cylindrical hub that supports the inner diameter of the magnetic disk, and a central hole of the stator. And a central shaft of the stator is a first circular hole,
A cylindrical stepped holder having a second circular hole concentric with the first circular hole and larger than the first circular hole, and fixed to the second circular hole; and the cylindrical stepped holder A spindle motor for a disk, wherein the fixed shaft is adhered and fixed to a peripheral surface, and a slight air gap is provided between the inner peripheral surface of the first circular hole and the fixed shaft. 2. The spindle motor for a disk according to claim 1, wherein the cylindrical stepped holder is made of an aluminum alloy. 3. A stator core is axially stacked,
A stator around which a winding is wound, a cylindrical magnet surrounding an air gap in the radial direction, a rotor yoke,
The rotor comprises a cylindrical hub that supports the inner diameter of the magnetic disk, and a fixed shaft that penetrates and is fixed in the center hole of the stator, and the diameter of the portion of the fixed shaft that abuts the center hole of the stator is reduced. A spindle motor for a disk, characterized in that an elastic adhesive is filled and the fixed shaft and the stator are adhesively fixed.