Slotless spindle motor for disc drive

• US 5,850,318 A
• Filed: 10/09/1996
• Issued: 12/15/1998
• Est. Priority Date: 06/06/1995
• Status: Expired due to Term

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Inventors: Heine, Gunter Karl, Dunfield, John C., Jufer, Marcel
• Primary Examiner(s): Wolff, John H.
• Application Number:
  US08/731,073
• Time in Patent Office: 797 Days
• Field of Search: 360/99.08, 360/98.01, 360/98.07, 360/99.06, 360/97.03, 310/90, 310/156, 310/261, 310/180, 310/181, 310/184, 310/901, 318/689
• US Class Current: 360/99.08
• CPC Class Codes: G11B 19/2009 Turntables, hubs and motors for disk drives; Mounting of motors in the drive means for clamping of disk to turntable G11B17/022 and subgroups
• CPC Class Codes: H02K 15/0478 Wave windings, undulated windings when on diagonally wound hollow coils H02K15/0492
• CPC Class Codes: H02K 21/12 with stationary armatures and rotating magnets
• CPC Class Codes: H02K 21/14 with magnets rotating within the armatures
• CPC Class Codes: H02K 21/22 with magnets rotating around the armatures, e.g. flywheel magnetos
• CPC Class Codes: H02K 3/04 Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
• CPC Class Codes: H02K 3/28 Layout of windings or of connections between windings windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32
• CPC Class Codes: H02K 5/163 radially supporting the rotary shaft at only one end of the rotor H02K5/165, H02K5/167, H02K5/173 take precedence
• CPC Class Codes: H02K 5/173 using bearings with rolling contact, e.g. ball bearings
• CPC Class Codes: H02K 7/085 radially supporting the rotary shaft at only one end of the rotor H02K7/086, H02K7/09 take precedence
• CPC Class Codes: H02K 7/086 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly H02K7/09 takes precedence

Abstract

A disc drive data storage system according to the present invention comprises a housing, a central axis, a stationary member which is fixed with respect to the housing and coaxial with the central axis, and a rotatable member which is rotatable about the central axis with respect to the stationary member. At least one data storage disc is attached to and is coaxial with the rotatable member. Upper and lower ball bearing assemblies interconnect the stationary member and the rotatable member. At least one rotor magnet is attached to the rotatable member. A back-iron is supported by the stationary member. A stator winding is attached to the back-iron and has a slotless structure. The rotor magnet, back-iron and stator winding have a common axial position along the central axis and the stator winding is magnetically coupled to the rotor magnet such that the stator winding and the rotor magnet cooperate to reduce excitation of pure tone vibrations in the disc drive data storage system and to reduce transfer of the vibrations to the housing through the ball bearing assemblies.

Claims

1. A disc drive data storage system, comprising:

a housing;

a central axis;

a stationary member which is fixed with respect to the housing and coaxial with the central axis;

a rotatable member which is rotatable about the central axis with respect to the stationary member;

at least one data storage disc attached to and coaxial with the rotatable member;

an actuator mounted to the housing;

a head carried by the actuator for communicating with the data storage disc;

an upper ball bearing assembly interconnecting the stationary member and the rotatable member;

a lower ball bearing assembly interconnecting the stationary member and the rotatable member;

at least one rotor magnet attached to the rotatable member;

a back-iron supported by the stationary member; and

a stator winding which is attached to the back-iron and has a slotless structure, wherein the rotor magnet, back-iron and stator winding have a common axial position along the central axis and have non-overlapping radial positions relative to the central axis and wherein the stator winding is magnetically coupled to the rotor magnet for rotating the rotatable member about the central axis and thereby moving the attached data storage disc relative to the head.

2. The disc drive data storage system of claim 1 wherein:

the axial position of the rotor magnet, the back-iron and the stator winding is between the upper and lower ball bearing assemblies, along the central axis.

3. The disc drive data storage system of claim 1 wherein:

the back-iron and stator winding have radial positions which are internal to the rotor magnet with respect to the central axis.

4. The disc drive data storage system of claim 1 wherein:

the rotatable member comprises a rotatable shaft positioned along the central axis and a hub which is coaxial with the rotatable shaft and has an inner diameter surface;

the stationary member comprises a stationary sleeve which is positioned adjacent the rotatable shaft and is coaxial with the rotatable shaft;

the upper and lower ball bearing assemblies each comprise an inner race supported by the rotatable shaft and an outer race supported by the stationary sleeve;

the back-iron is attached to an outer diameter surface of the stationary sleeve;

the stator winding is attached to an outer diameter surface of the back-iron; and

the rotor magnet is attached to the inner diameter surface of the hub and has a radial position that is external to the stator winding with respect to the central axis.

5. The disc drive data storage system of claim 4 wherein:

the axial position of the rotor magnet, the back-iron and the stator winding is between the upper and lower ball bearing assemblies, along the central axis.

6. The disc drive data storage system of claim 1 and further comprising a stationary shaft which is positioned along the central axis and wherein:

the stationary shaft has an outer diameter surface;

the rotatable member comprises a hub having an inner diameter surface;

the back-iron has an inner diameter surface which is attached to the outer diameter surface of the stationary shaft;

the stator winding is attached to an outer diameter surface of the back-iron; and

the rotor magnet is supported at the inner diameter of the hub and has a radial position which is external to the back-iron and the stator winding with respect to the central axis.

7. The disc drive data storage system of claim 6 wherein:

the axial position of the rotor magnet, the back-iron and the stator winding is between the upper and lower ball bearing assemblies, along the central axis.

8. The disc drive data storage system of claim 6 wherein:

the rotatable member further comprises a bearing sleeve attached to the inner diameter surface of the hub; and

the upper and lower ball bearing assemblies each comprise an inner race supported by the stationary shaft and an outer race supported by the bearing sleeve.

9. The disc drive data storage system of claim 1 wherein:

the rotatable member comprises a hub which carries the data storage disc; and

the axial position of the back-iron, stator winding and rotor magnet is below the hub and the upper and lower ball bearing assemblies.

10. The disc drive data storage system of claim 9 wherein:

the housing comprises a base having a recessed cavity which forms the stationary member, wherein the recessed cavity has an inner diameter surface;

the back-iron and stator winding are positioned at the inner diameter surface and attached to the base within the recessed cavity; and

the rotor magnet is positioned within the recessed cavity and has a radial position which is external to the stator winding with respect to the central axis.

11. The disc drive data storage system of claim 1 wherein:

the back-iron comprises a stack of stator laminations having a radial surface;

the stator winding is attached to the radial surface of the stack of stator laminations and is entirely external to the stack of stator laminations with respect to the central axis.

12. The disc drive data storage system of claim 1 wherein:

the stator winding has a cylindrical shape which is formed of a plurality of interwoven phase windings and is coaxial with the rotor magnet.

13. The disc drive data storage system of claim 1 wherein:

the stator winding comprises a plurality of individual phase windings distributed about a circumference of the back-iron, with each phase winding forming a loop having a loop axis, a loop plane and a loop center, wherein the loop axis is normal to the loop plane and intersects the loop center and wherein the loop axis is normal to and intersects the central axis.

14. The disc drive data storage system of claim 1 wherein the back-iron is formed of a solid magnetic material.

15. The disc drive data storage system of claim 1 wherein the rotor magnet is formed in a unitary, multipolar ring of magnetized material, which is attached to and coaxial with the rotatable member.

16. The disc drive data storage system of claim 1 wherein the magnet is formed of a plurality of individual magnets which are attached to and arranged coaxial with the rotatable member.

17. A spindle motor for a disc drive data storage system, comprising:

a central axis;

a housing;

a stationary member which is fixed with respect to the housing;

hub means for carrying at least one data storage disc;

rotor means comprising a magnet for rotating the hub means with respect to the central axis in response to a rotating magnetic field;

an actuator mounted to the housing;

a head carried by the actuator for communicating with the data storage disc;

ball bearing means for interconnecting the hub means and the stationary member; and

slotless stator winding means having a common axial position with the magnet along the central axis for generating the rotating magnetic field such that the slotless stator winding means and the magnet cooperate to rotate the hub means about the central axis and thereby moving the attached data storage disc relative to the head.

18. The spindle motor of claim 17 wherein the rotor means and the slotless stator winding means cooperate to rotate the hub means above 10,000 RPM.