Disk storage device having an underhub spindle motor

• US RE38,178 E1
• Filed: 06/18/1999
• Issued: 07/08/2003
• Est. Priority Date: 05/10/1980
• Status: Expired due to Term

• Current Assignee: Papst Licensing GmbH & Company Kg
• Original Assignee: Papst Licensing GmbH & Company Kg
• Inventors: Müller, Rolf, von der Heide, Johann, Elsässer, Dieter
• Primary Examiner(s): HEINZ, ALLEN J
• Application Number:
  US09/333,396
• Time in Patent Office: 1,481 Days
• Field of Search: 360/98.07, 360/99.08, 360/98.08, 360/99.12
• US Class Current: 360/98.07
• CPC Class Codes: G11B 17/038 Centering or locking of a plurality of discs in a single cartridge
• CPC Class Codes: G11B 19/20 Driving; Starting; Stopping; Control thereof
• 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: G11B 23/505 of disk carriers
• CPC Class Codes: G11B 25/043 using rotating discs
• CPC Class Codes: H02K 11/01 for shielding from electromagnetic fields , i.e. structural association with shields means for preventing or reducing eddy-current losses in the winding heads by shielding H02K3/42
• CPC Class Codes: H02K 11/21 Devices for sensing speed or position, or actuated thereby specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 11/40 Structural association with grounding devices
• CPC Class Codes: H02K 21/22 with magnets rotating around the armatures, e.g. flywheel magnetos
• CPC Class Codes: H02K 2211/03 Machines characterised by circuit boards, e.g. pcb
• CPC Class Codes: H02K 29/08 using magnetic effect devices, e.g. Hall-plates, magneto-resistors H02K29/12 takes precedence
• 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 5/10 with arrangements for protection from ingress, e.g. water or fingers
• CPC Class Codes: H02K 5/124 Sealing of shafts
• CPC Class Codes: H02K 5/167 using sliding-contact or spherical cap bearings
• CPC Class Codes: H02K 5/1735 radially supporting the rotary shaft at only one end of the rotor H02K5/1737 takes precedence
• CPC Class Codes: H02K 5/1737 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
• CPC Class Codes: H02K 5/225 Terminal boxes or connection arrangements specially adapted for submersible motors H02K5/132
• CPC Class Codes: H02K 7/08 Structural association with 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
• CPC Class Codes: H02K 7/14 : Structural association with mechanical loads, e.g. with hand-held machine tools or fans with fan or impeller for cooling the machine H02K9/06
• CPC Class Codes: H02P 2209/07 : Trapezoidal waveform
• CPC Class Codes: H02P 6/085 : in a bridge configuration
• CPC Class Codes: H02P 6/14 : Electronic commutators

Abstract

A disk memory drive includes a brushless drive outer rotor motor having an internal space and a stator with windings. The outer rotor coaxially encircles the stator and a substantially cylindrical air gap is defined between the stator and the rotor. The rotor includes permanent magnets and a hub fixedly connected with the magnet. A disk mounting section is provided on the hub for accommodating at least one storage disk positioned in a clear space, the mounting section being adapted to extend through a central aperture of the storage disk. The windings and the magnets interacting with the windings are disposed for at least half of the axial longitudinal dimension thereof within a space surrounded by the disk mounting section of the hub. Bearings rotatably mount the rotor and the hub.

Claims

1. A disk memory drive comprising:

a brushless drive motor having an internal space defined therein and a stator including winding means defining magnetically active parts of the drive motor and having a given axial extension, the motor having an outer rotor with an inner circumference, an outer circumference and an open end coaxially encircling the stator and a substantially cylindrical air gap defined between the stator and the rotor, the rotor including a separate non ferromagnetic hub and a soft iron ring element interiorly of said hub and radially located means forming a permanent magnet interiorly of said ring having a predetermined axial extension fixedly connected therewith for magnetic interaction with said winding means;

a disk mounting section provided on the outside of said hub for accommodating at least one storage disk for location in a clean chamber surrounding said rotor when the drive motor is mounted for operation, the disk mounting section on the hub along its axial length being adapted to extend through a central aperture of the storage disk, the winding means and the magnet means interacting therewith being disposed for at least half of the axial extension thereof within a space surrounded by the disk mounting section of the hub; and

first and second axially separated bearing means having inner and outer races on a shaft rotatably mounting the rotor and the hub on the shaft, the motor also including rotating means interacting with stationary means for determining the rotational position of the rotor, the internal space of said motor, which includes the internal portions thereof with the bearing means, being sealed off against the clean chamber when the drive motor is mounted for operation, a disk-shaped ring member being located with precision at the open end of the rotor between the inner circumference of the rotor and the outer race of one of the axially separated bearing means, and means stationary containing leads establishing electrical connection between the internal space and the outside of the motor.

2. A disk memory drive according to claim 1, wherein said rotating means interacting with said stationary means comprises rotational position indicator means which includes permanent magnet poles disposed on the disk-shaped ring member for rotation therewith and wherein the rotational position sensor means is sensitive to magnetic fields and interacts with the permanent magnet poles.

3. A disk memory drive according to claim 2, wherein the shaft is a stationary shaft.

4. A disk memory drive according to claim 3 wherein the rotational position sensor means is mounted on a printed circuit board opposite the disk-shaped member ring.

5. A disk memory drive according to claim 4, further including electronic commutation devices for the electromagnetization of the stator also being mounted on the printed circuit board.

6. A disk memory drive according to claim 4, wherein the printed circuit board is supported on a flange fixed to the stationary shaft.

7. A disk memory drive according to claim 3, further including a magnetic shield means at least circumferentially surrounding the stator for shielding a clean chamber containing the disk from the magnetic flux of the stator and wherein the stationary shaft is of constant diameter and the outer rotor includes a bell-shaped housing with a substantially closed end and a substantially open end, the stator together with the magnetic shield being firmly mounted to the stationary shaft, the inner race of each bearing being firmly mounted on the stationary shaft on either axial side of the stator, the upper bearing being positioned inwardly adjacent of the closed end of the bell-shaped outer rotor, and the lower bearing being positioned adjacent the open end of the bell-shaped outer rotor.

8. A disk memory drive according to claim 2, wherein the internal space of the motor is sealed by means of a cover located at the open end of the outer rotor, the cover also serving as a bearing mounting flange, and the rotational position indicator means being mounted on the outside of the motor cover with respect to the sealed inner space of the motor.

9. A disk memory drive according to claim 2, wherein the outer rotor includes an outer rotor casing of ferromagnetic material, the outer rotor serving also as the hub, the rotational position indicator being mounted on a lower part of the hub outside the sealed inner space of the motor.

10. A disk memory drive according to claim 2, further comprising a bearing mounting flange having projections in the actual axial direction that project into the disk-shaped ring member, and a labyrinth seal located between the projections and the ring member formed by a combination of cylindrical and radially flat gaps having only dimensions of normal clearances between moving parts.

11. A disk memory drive according to claim 10, wherein the projections on the bearing mounting flange are rectangular in section and extend axially.

12. A disk memory drive according to claim 10, wherein the ring member on which part of the bearing race is mounted is substantially flush in the axial direction with the mounting flange, the ring member being inserted in the outer rotor casing that forms the hub.

13. A disk memory drive having a brushless drive motor, comprising a stator having a predetermined axial extension, a coaxially positioned outer rotor encircling the stator and defining therebetween a substantially cylindrical air gap, the rotor having an inner circumference and an outer circumference and a predetermined axial extension, a cylindrically shaped permanent magnet having a predetermined axial extension disposed adjacent the air gap on the inner circumference of the rotor to rotate therewith and magnetically interact with the stator, a ferromagnetic hub on the outer circumference of the rotor firmly fixed to the motor magnet, the hub radially surrounding the predetermined axial extension of said permanent magnet and being provided on its outer circumference with a disk mounting section which can extend through the central opening in a storage disk to mount at least one storage disk thereon, a shaft having first and second axially separated bearing means mounted thereon rotatably mounting the rotor with hub on the shaft, and seals located axially outside of the axial extension of the first and second bearing means for sealing the space therebetween.

14. A disk memory drive according to claim 13, wherein the shaft is a stationary shaft.

15. A disk memory drive according to claim 14, wherein the seals are magnetic liquid seals.

16. A disk memory drive according to claim 14, wherein the seals are labyrinth seals.

17. A disk memory drive according to claim 14, wherein the stationary shaft projects axially externally of the upper and lower seals.

18. A disk memory drive according to claim 14, wherein the labyrinth seal is formed of a member having a substantially L-shaped cross section, being mounted on and extending radially from the stationary shaft, the short leg of the L-shaped member extending axially outwardly.

19. A disk memory drive according to claim 16, further including a ring member of L-shaped cross section being provided on the rotor and being opposite and complementary to the stationary mounted L-shaped member, the longer leg of the L-shaped member on the rotor extending inwardly toward the stationary shaft with only a clearance dimension separating the two parts.

20. A disk memory drive according to claim 16, wherein the stationary L-shaped member lies inboard axially and is substantially encompassed by the rotating L-shaped ring, a flat radial labyrinth gap being formed radially between the respective short legs of the L-shaped members.

21. A disk storage device, comprising in combination:

22. The disk storage device of claim 21 wherein the outside diameter of the generally cylindrical portion of said hub member is smaller than at least one of the distances specified in a group consisting of:

the outer diameter of said permanent magnetic ring, the inner diameter of said magnetically conductive member, and the outer diameter of said magnetically conductive member.

23. The disk storage device of claim 21 wherein said magnetically conductive member provides at least a portion of a magnetic return path for said permanent magnetic ring.

24. The disk storage device of claim 21 wherein said shaft is rotatable about said axis.

25. The disk storage device of claim 21 wherein said permanent magnetic ring is formed from a generally radially oriented material.

26. The disk storage device of claim 25 wherein said permanent magnetic ring is radially magnetized to form a plurality of permanent magnets of alternating polarity, the radial magnetization of said permanent magnets varies in a substantially trapezoidal manner in a circumferential direction, and a pole gap is defined between the magnetic poles in each of said permanent magnets such that the circumferential extent of each dole gap is small compared to the circumferential extent of the magnetic poles in the pair of permanent magnets adjacent thereto.

27. The disk storage device of claim 26 wherein said permanent magnetic material comprises a mixture of ferrite and an elastic material.

28. The disk storage device of claim 21 said hub member comprises a generally non-magnetically conductive material.

29. The disk storage device of claim 28 wherein said generally non-magnetically conductive material comprises a light metal.

30. The disk storage device of claim 29 wherein said light metal comprises aluminum.

31. The disk storage device of claim 21 wherein said rotor comprises an external rotor.

32. The disk storage device of claim 21 wherein said permanent magnetic ring coaxially surrounds the portion of said stator that forms said generally cylindrical air gap.

33. A disk storage device, comprising in combination:

34. The disk storage device of claim 33 wherein said magnetically conductive member provides at least a portion of a magnetic return path for said permanent magnetic ring.

35. The disk storage device of claim 33 wherein said shaft is rotatable about said axis.

36. The disk storage device of claim 33 wherein said permanent magnetic ring is formed from a generally radially oriented material.

37. The disk storage device of claim 36 wherein said permanent magnetic ring is radially magnetized to form a plurality of permanent magnets of alternating polarity, the radial magnetization of said permanent magnets varies in a substantially trapezoidal manner in a circumferential direction, and a pole gap is defined between the magnetic poles in each of said permanent magnets such that the circumferential extent of each pole gap is small compared to the circumferential extent of the magnetic poles in the pair of permanent magnets adjacent thereto.

38. The disk storage device of claim 37 wherein said permanent magnetic material comprises a mixture of ferrite and an elastic material.

39. The disk storage device of claim 33 said hub member comprises a generally non-magnetically conductive material.

40. The disk storage device of claim 39 wherein said generally non-magnetically conductive material comprises a light metal.

41. The disk storage device of claim 40 wherein said light metal comprises aluminum.

42. The disk storage device of claim 33 wherein said rotor comprises an external rotor.

43. The disk storage device of claim 33 wherein said permanent magnetic ring coaxially surrounds the portion of said stator that forms said generally cylindrical air gap.