JP2971114B2 - Spindle motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a spindle motor used for driving a recording member such as an optical disk and a magnetic disk.

[PRIOR ART AND PROBLEMS] Generally, a spindle motor for driving a magnetic disk includes a stationary member such as a bracket, a hub member on which the magnetic disk is mounted, and a bearing interposed between the stationary member and the hub member. The magnetic disk is accommodated in a disk chamber filled with clean air. The spindle motor is provided with a seal mechanism such as a magnetic fluid seal mechanism and a labyrinth seal mechanism so that unclean air existing inside does not flow into the disk chamber.

However, in this type of spindle motor,
When a lubricant having a relatively high viscosity is used for the bearing member, there is a problem that torque loss increases due to the viscosity and mounting current increases. On the other hand, when a relatively low-viscosity lubricant is used for the bearing member, the lubricant is easily scattered, and therefore, the lubricant easily enters the disk chamber.

[Object of the Invention] The present invention has been made in view of the above facts, and a main object of the present invention is to provide a relatively inexpensive spindle motor capable of preventing torque from flowing into a disk chamber while suppressing torque loss. It is to provide.

[Summary of the Invention] According to the present invention, a stationary member, a hub member to which a recording member is mounted, a pair of bearing members interposed between the stationary member and the hub member, and the pair of bearing members A seal mechanism disposed outside the rotor, a rotor magnet mounted on the hub member, and a stator disposed opposite to the rotor magnet, wherein one of the pair of bearing members is provided. , A relatively low-viscosity lubricant is used, and the other uses a relatively high-viscosity lubricant.

[Embodiment of the Invention] Fig. 1 shows an example of a spindle motor according to the present invention, and shows a cross-sectional view of a spindle motor on which, for example, four 3.5-inch magnetic disks are mounted.

In FIG. 1, 1 is a shaft, 2 is a bracket constituting a stationary member, 3 is an upper bearing, 4 is a lower bearing, 5 is a stator, 6 is a rotor magnet, 7 is an auxiliary yoke, and 8 is a hub on which a disk is mounted. Reference numeral 9 denotes a magnetic fluid seal mechanism, 12 denotes a rabbling seal mechanism, 41 denotes a bush, 42 denotes an index magnet fixed to the bush 41, 23 denotes a magnetic sensor, and 52 denotes a flexible circuit board.

A hub member 8 on which a disk (not shown) is mounted has a bell-shaped outer shape made of, for example, aluminum material, and rotates via a pair of bearings (upper bearing 3 and lower bearing 4) externally fitted and fixed to the shaft 1. It is freely supported. A plurality of screw holes (not shown) are provided in the upper portion of the hub member 8 in a circumferential shape, and a clamping member (not shown) is screwed into a mounting screw (not shown). Is attached.

A roller magnet 6 is provided on the inner peripheral surface of the hub member 8.
Are fixed via an auxiliary yoke 7. In a specific example,
A bush 41 is inserted between the lower bearing 4 and the auxiliary yoke 7.

On the other hand, the shaft 1 is made of, for example, a carbon steel material, and the stator 5 is externally fitted and fixed to an outer peripheral surface 11 at a substantially central portion thereof. Then, the hub 8 is driven to rotate by the relative rotation between the rotor magnet 6 and the stator 5. The lower end of the shaft 1 is fitted and fixed to a bracket 2.
Are fixed to a base (not shown) of the magnetic disk drive. The bracket 2 uses, as an example, an aluminum material that is easy to process like the hub member 8. A flexible circuit board 52 is adhered to the lower surface of the bracket 2, and the magnetic sensor 23 is provided on the circuit board 52. The magnetic sensor 23 detects the magnetic force transmitted from the index magnet 42 fixed to the bush 41 on the hub member 8 through the thin portion 24 of the bracket 2 made of a non-magnetic aluminum material.

A lead wire 51 led out of a coil of the stator 5 is electrically connected to a flexible circuit board 52 through a lead hole 41 provided in the shaft 1 by soldering or the like.

Then, one end 53 of the flexible circuit board 52 is extended as it is, led out of the spindle motor, and electrically connected to the connector on the drive device side.

The magnetic fluid seal mechanism 9 is composed of a magnetic circuit unit in which a donut-shaped magnet is sandwiched between ferromagnetic pole pieces, and a magnetic fluid filled and held in a gap between the unit and the shaft 1. The interior of the motor and the disk chamber 10 are partitioned by the magnetic fluid layer generated in step (1).

The protective cap 90 is provided to prevent the magnetic fluid layer from diffusing out of the hub member 8, that is, into the disk chamber 10 when the magnetic fluid layer is scattered due to a pressure difference between the inside and outside.

A labyrinth seal mechanism 12 is provided between the hub member 8 and the bracket 2. In a specific example, an annular protrusion 87 protruding toward the bracket 2 is provided on the lower end surface of the flange portion 83 of the hub member 8, and an annular concave portion for receiving the tip of the annular protrusion 87 is provided on the inner surface of the bracket 2. An annular projection 87 and an annular concave portion 88 are formed.
88 constitutes the labyrinth seal mechanism 12. The labyrinth seal mechanism 12 allows the space 20 inside the spindle motor
And the disc chamber space 10 are substantially sealed.

As described above, the magnetic fluid seal mechanism 9 and the labyrinth seal mechanism are provided above and below the hub member 8 of the spindle motor.
Since 12 is provided, clean air is kept in the disk chamber 10.

In a specific example, the upper bearing 3 is a ball bearing type, and a relatively low-viscosity lubricant is used in connection with the magnetic fluid sealing mechanism 9 being disposed nearby. Such a lubricant has a viscosity of 10-30cs at 40 ° C.
Preferably, for example, those sold by Kyodo Yushi Co., Ltd. under the trade name `` Multemp SRL '',
Or KLBER LUBRICATION MNCHE
NKG) sold under the trade name "Isoflex Super LDS18" can be used. As the viscosity of the lubricant used decreases, a part of the lubricant used for the upper bearing 3 is scattered, and the tendency of mist to be easily generated increases. Since the inside and outside of the spindle motor are securely sealed by the magnetic fluid sealing mechanism 9, there is no danger that the mist of the lubricant will diffuse into the disk chamber 10. That is, since the use of the lubricant for the upper bearing 3 to be used is greatly permitted by mounting the magnetic fluid seal mechanism 9, the type of the lubricant having the smallest possible torque loss can be selected.

On the other hand, although the lower bearing 4 is a ball bearing type, a relatively high-viscosity lubricant is used in connection with the labyrinth seal mechanism 12 being disposed in the vicinity. The lubricant preferably has a viscosity of 80 to 110 cst at 40 ° C. For example, a lubricant sold under the trade name “Andoc C” by Esso Standard Oil Co., Ltd. can be used. In the labyrinth seal mechanism 12, since air somewhat flows between the annular convex portion 87 and the annular concave portion 88, mist of the lubricant may pass through the labyrinth seal mechanism 12 on the flow of the air. Therefore, in order to reduce this possibility as much as possible, it is important to make the viscosity of the lubricant relatively large, so that scattering of the lubricant itself can be suppressed, and the labyrinth sealing effect can be improved.

As described above, the spindle motor according to the present embodiment employs the magnetic fluid sealing mechanism 9 corresponding to the upper bearing 3 using a relatively low-viscosity lubricant, and uses the lower fluid using a relatively high-viscosity lubricant. A labyrinth seal mechanism 12 was used corresponding to the side bearing 4.

As described above, one specific example of the spindle motor according to the present invention has been described. However, the present invention is not limited to the specific example, and various modifications and modifications can be made without departing from the scope of the present invention.

For example, in this specific example, a ball bearing type bearing has been described as a bearing member, but other bearing types can also be selected.

Also, for example, in this specific example, a magnetic fluid sealing mechanism 9 is provided at the upper end of the hub member 8, and a relatively low-viscosity lubricant is used for the upper bearing 3 in connection with this. A labyrinth seal mechanism 12 is provided at the lower end of the lower bearing 8 and a relatively high-viscosity lubricant is used for the lower bearing 4 in connection with this.
A labyrinth seal mechanism is disposed at the upper end of the upper bearing, and in connection with this, a relatively high-viscosity lubricant is used for the upper bearing 3,
Further, a magnetic fluid sealing mechanism may be provided at the lower end of the hub member 8, and in this connection, a relatively low-viscosity lubricant may be used for the lower bearing 4.

[Effects of the Invention] The present invention has the above-described configuration, and has the following effects. By using different viscosities of the lubricants used for the pair of bearings, it is possible to effectively prevent the mist of the lubricant from flowing into a room such as a disk room while suppressing torque loss.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a specific example of a spindle motor according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Shaft 2 ... Bracket 3, 4 ... Bearing 5 ... Stator 6 ... Rotor magnet 7 ... Auxiliary yoke 8 ... Hub member 9 ... Magnetic fluid seal mechanism 12 ... Labyrinth seal mechanism

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02K 5/15 H02K 21/22 F16J 15/40 F16J 15/43 F16J 15/447

Claims (2)

(57) [Claims] 1. A stationary member, a hub member to which a recording member is mounted, a pair of bearing members interposed between the stationary member and the hub member, and a pair of bearing members disposed outside the pair of bearing members. A spindle motor comprising a sealing mechanism, a rotor magnet mounted on the hub member, and a stator disposed opposite the rotor magnet, wherein one of the pair of bearing members has a viscosity comparison. A spindle motor, characterized by using a lubricating oil having a relatively low viscosity, and a lubricant having a relatively high viscosity being used for the other of them. 2. A magnetic fluid seal mechanism is provided outside one of the pair of bearing members, and a labyrinth seal mechanism is provided outside the other of the pair of bearing members. 2. A relatively low-viscosity lubricant is used for the one bearing member, and a relatively high-viscosity lubricant is used for the other bearing member in connection with the labyrinth seal mechanism. Spindle motor.