High speed spindle motor with hydrodynamic bearings

• US 6,300,695 B1
• Filed: 12/22/1999
• Issued: 10/09/2001
• Est. Priority Date: 07/29/1999
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Encap Motor Corporation
• Inventors: Neal, Griffith D.
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): Lam, Thanh
• Application Number:
  US09/470,425
• Time in Patent Office: 657 Days
• Field of Search: 310/68.D, 310/90, 310/67.R, 310/156, 310/64, 360/99.06, 360/99.07, 360/99.08, 360/99.04, 384/107, 384/100, 384/112
• US Class Current: 310/68.00D
• 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 1/146 consisting of a generally annular yoke with salient poles
• CPC Class Codes: H02K 1/185 to outer stators
• CPC Class Codes: H02K 1/187 to inner stators
• CPC Class Codes: H02K 11/00 Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection casings, enclosures or supports H02K5/00
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 15/10 Applying solid insulation to windings, stators or rotors
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 15/16 Centering rotors within the stator; Balancing rotors
• CPC Class Codes: H02K 21/16 having annular armature cores with salient poles with homopolar co-operation H02K21/20
• CPC Class Codes: H02K 21/22 with magnets rotating around the armatures, e.g. flywheel magnetos
• CPC Class Codes: H02K 21/24 with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• CPC Class Codes: H02K 2211/03 Machines characterised by circuit boards, e.g. pcb
• CPC Class Codes: H02K 3/38 around winding heads, equalising connectors, or connections thereto
• CPC Class Codes: H02K 3/46 Fastening of windings on the stator or rotor structure
• CPC Class Codes: H02K 5/02 Casings or enclosures characterised by the material thereof
• CPC Class Codes: H02K 5/08 Insulating casings
• CPC Class Codes: H02K 5/1675 radially supporting the rotary shaft at only one end of the rotor H02K5/1677 takes precedence
• CPC Class Codes: H02K 5/1677 radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
• CPC Class Codes: H02K 5/1732 radially supporting the rotary shaft at both ends of the rotor H02K5/1737 takes precedence
• 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 7/085 : radially supporting the rotary shaft at only one end of the rotor H02K7/086, H02K7/09 take 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

Abstract

The present invention is directed to a high speed spindle motor comprising a stator assembly including a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted by the conductors and a body of a phase change material such as a thermoplastic substantially encapsulating the stator. A rotatable hub having a magnet connected thereto is in operable proximity to the stator. The high speed motor also includes a shaft, a bearing surrounding the shaft and one of the bearing or shaft being fixed to the stator assembly and the other of the bearing or shaft being fixed to the rotatable hub. Hard disc drives using the motor, and methods of developing and constructing the motor and hard disc drives are also disclosed.

Claims

1. A high speed spindle motor comprising:

a) a stator assembly comprising a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted through the conductors and a body of a phase change material having a coefficient of linear thermal expansion of less than 2×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F. encapsulating the stator;

b) a rotatable hub having a magnet connected thereto in operable proximity to the stator;

c) a shaft; and

d) a hydrodynamic bearing surrounding the shaft, one of the bearing or shaft being fixed to the stator assembly and the other of the bearing or shaft being fixed to the hub.

2. The high speed spindle motor of claim 1 wherein the hydrodynamic bearing is fixed to the body of phase change material.

3. The high speed motor of claim 1 wherein the phase change material has a coefficient of linear thermal expansion of less than 1.5×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

4. The high speed motor of claim 1 wherein the phase change material has a coefficient of linear thermal expansion of between about 0.8×

10<sup>−

5</sup> in/in/°

F. and about 1.2×

10<sup>−

5</sup> in/in/°

F. throughout the range of 0-250°

F.

5. The high speed motor of claim 1 wherein the bearing comprises steel, the hub comprising aluminum and the coefficient of linear thermal expansion of the phase change material is between the coefficient of linear thermal expansion of the steel and the coefficient of linear thermal expansion of the aluminum.

6. The high speed spindle motor of claim 1 wherein the hydrodynamic bearing comprises an inner portion fixed to the shaft and an outer portion fixed to the body of phase change material.

7. The high speed motor of claim 1 wherein the phase change material includes ceramic particles.

8. The high speed spindle motor of claim 1 wherein the body of phase change material is a monolithic body, the body being configured to align the shaft, the hub and the bearing with respect to one another.

9. A high speed spindle motor comprising:

a) a stator assembly comprising;

i) a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted by the conductors; and

ii) a body of a phase change material substantially encapsulating the stator;

b) a rotatable hub having a magnet connected thereto in operable proximity to the stator;

c) a hydrodynamic bearing allowing the hub to rotate with respect to the stator assembly; and

d) a solid insert substantially encapsulated within the body, the insert enhancing heat transfer away from the bearing and the stator.

10. The high speed motor of claim 9 wherein the insert provides structural rigidity to the stator assembly.

11. The high speed motor of claim 9 wherein the insert enhances dampening of motor vibration.

12. The high speed motor of claim 9 wherein the insert enhances dampening of audible noise.

13. The high speed spindle motor of claim 9 wherein the phase change material comprises an injection molded thermoplastic have a vibration dampening such that the stator assembly has a reduction of harmonics in the range of 300-2000 Hz of at least 5 decibles compared to a spindle motor with the same stator not being encapsulated.

14. The high speed motor of claim 9 wherein the spindle motor comprises a pancake motor and the conductors comprise windings mounted on a circuit board.

15. The high speed motor of claim 9 wherein the stator further comprises a core of steel laminations having a plurality of poles and the conductors comprise windings around said poles that induce magnetic fields in the core when current is conducted by the conductors.

16. The high speed motor of claim 9 wherein the phase change material has a thermal conductivity of at least 0.7 watts/meter°

K.

17. A high speed spindle motor comprising:

a) a stator assembly comprising;

i) a stator having multiple conductors that create a plurality of magnetic fields when electrical current is conducted by the conductors;

ii) a body of phase change material substantially encapsulating the conductors, the phase change material having a thermal conductivity of at least 0.7 watts/meter°

K;

b) a rotatable hub having a magnet connected thereto in operable proximity to the stator; and

c) a hydrodynamic bearing allowing the hub to rotate with respect to the stator assembly.

18. The high speed motor of claim 17 wherein the phase change material has a dielectric strength of at least 250 volts/mil.

19. The high speed motor of claim 17 wherein the phase change material comprises polyphenyl sulfide.

20. The high speed spindle motor of claim 17 wherein the hydrodynamic bearing is press fit into a cylindrical hole in the body of phase change material.