Method and apparatus for enabling cold temperature performance of a disk

• US 6,735,035 B1
• Filed: 11/20/2000
• Issued: 05/11/2004
• Est. Priority Date: 11/20/2000
• Status: Expired due to Fees

• Current Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Smith, Gordon James, Van Leeuwen, George Willard
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): OLSON, JASON C
• Application Number:
  US09/714,952
• Time in Patent Office: 1,268 Days
• Field of Search: 360/69, 360/73.03, 360/75, 360/97.02, 700/79, 700/299, 700/300
• US Class Current: 360/69
• CPC Class Codes: F16C 2370/12 Hard disk drives or the like
• CPC Class Codes: F16C 33/6603 with grease as lubricant
• 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

Abstract

In cold weather, the higher torque required for normal spinning operation of a spindle motor assembly in a direct access storage device due to the increased viscosity of the grease, is overcome by localizing the heating to the spindle motor assembly to reduce the viscosity of the grease, and then let a disk driven self heat during and after spin-up of the spindle motor assembly.

Claims

1. A method for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD) after receipt of a power-on command for the DASD, comprising:

(a) measuring a temperature of said DASD;

(b) starting spinning operation of said spindle motor assembly immediately unless the temperature measured in step (a) is below a minimum threshold temperature for normal operation;

(c) if the temperature measured in step (a) is below the minimum threshold temperature for normal operation, applying a current to windings of said spindle motor assembly to raise the temperature of said spindle motor assembly; and

(d) starting spinning operation of said spindle motor assembly after the temperature has been raised.

2. A method according to claim 1, wherein said current applied in step (c) is any one of a DC current, an AC current and a pulsed current.

3. A method according to claim 2, wherein said current is applied to said windings of said spindle motor assembly for an amount of time required for the resistance of a respective one of said windings to reach a predetermined value corresponding to the applied current.

4. A method according to claim 2, wherein said current is applied to said windings of said spindle motor assembly for an amount of time required for the electrical resistance of a respective one of said windings to reach a predetermined value based on a table stored in a controller in said DASD.

5. A method according to claim 4, wherein the values of resistance of said windings corresponding to current values stored in said table in said controller are predetermined by measuring changing resistance values in respective ones of said windings in accordance with a change in an amount of current or voltage applied to the respective winding.

6. A method according to claim 2, wherein said current applied to said windings of said spindle motor assembly in step (c) corresponds to a measured temperature of said DASD in a table stored in a controller of said DASD.

7. A method according to claim 6, wherein said spindle motor assembly includes bearings, and wherein said current is applied to said windings for an amount of time required for the bearings of said spindle motor assembly to reach a predetermined minimum threshold temperature.

8. A method according to claim 2, wherein said temperature of said DASD is measured in step (a) using a thermistor on a card therein.

9. A method according to claim 2, wherein said temperature of said DASD is measured in step (a) using a sensor on said spindle motor assembly.

43. A method according to claim 1, wherein step (c) is conducted for an amount of time required for the temperature of said spindle motor assembly to rise to the minimum threshold temperature for normal operation.

44. A method according to claim 1, wherein step (d) comprises supplying electrical power to said spindle motor assembly, measuring the current drawn by said spindle motor assembly, and continuing with step (d) only if the measured current is less than a predetermined maximum current value.

45. A method according to claim 44, further comprising applying a current to the windings of said spindle motor assembly again to raise the temperature thereof above the minimum threshold temperature for normal operation if the measured current is not less than the maximum current value.

46. A method according to claim 9, wherein the sensor is a thermistor.

52. A method according to claim 4, wherein the sensor is a thermistor.

10. A method for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD), comprising:

measuring a temperature of said DASD;

exciting the phases of said spindle motor assembly for an amount of time required for the temperature of said spindle motor assembly to rise to a minimum threshold temperature for normal operation; and

starting spinning operation of said spindle motor assembly,

wherein exciting said phases of said spindle motor assembly includes rocking said phases back-and-forth in a clockwise-counterclockwise manner at a predetermined rate of speed.

11. A method according to claim 10, wherein said phases of said spindle motor assembly are excited until a bearing assembly of said spindle motor assembly reaches a minimum threshold temperature.

12. A method according to claim 11, wherein said phases of said spindle motor assembly are excited until the grease of said bearing assembly of said spindle motor assembly reaches a minimum threshold temperature.

13. A method according to claim 10, wherein said temperature of said DASD is measured using a thermistor on a card therein.

14. A method according to claim 10, wherein said temperature of said DASD is measured using a sensor on said spindle motor assembly.

47. A method according to claim 14, wherein the sensor is a thermistor.

15. A method for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD) after receipt of a power-on command for the DASD, comprising:

(a) measuring a temperature of said DASD;

(b) starting spinning operation of said spindle motor assembly immediately unless the temperature measured in step (a) is below a minimum threshold temperature for normal operation;

(c) heating said spindle motor assembly to raise the temperature thereof; and

(d) starting spinning operation of said spindle motor assembly after the temperature has been raised.

16. A method according to claim 15, wherein heating said spindle motor assembly in step (c) is performed for an amount of time that corresponds to the measured temperature of said DASD in a table stored in a controller of said DASD.

17. A method according to claim 15, wherein said spindle motor assembly includes bearings, and wherein heating said spindle motor assembly including applying a current to said windings for an amount of time required for the bearings of said spindle motor assembly to reach a predetermined minimum threshold temperature.

18. A method according to claim 15, wherein said temperature of said DASD is measured in step (a) using a thermistor on a card therein.

19. A method according to claim 15, wherein said temperature of said DASD is measured in step (a) using a thermistor on said spindle motor assembly.

48. A method according to claim 15, wherein step (c) is conducted for an amount of time required for the temperature of said spindle motor assembly to rise to the minimum threshold temperature for normal operation.

49. A method according to claim 15, wherein step (d) comprises supplying electrical power to said spindle motor assembly, measuring the current drawn by said spindle motor assembly, and continuing with step (d) only if the measured current is less than a predetermined maximum current value.

50. A method according to claim 49, further comprising applying a current to the windings of said spindle motor assembly again to raise the temperature thereof above the minimum threshold temperature for normal operation if the measured current is not less than the maximum current value.

51. A method according to claim 19, wherein the sensor is a thermistor.

20. A program for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD), comprising:

a code for measuring a temperature of said DASD using a sensor on said motor spindle assembly;

a code for applying a current to windings of said spindle motor assembly for an amount of time required for the temperature of said spindle motor assembly to rise to a minimum threshold temperature for normal operation; and

a code for starting spinning operation of said spindle motor assembly when the temperature of said spindle motor assembly has risen to the minimum threshold temperature for normal operation.

21. A program according to claim 20, wherein said current is any one of a DC current, an AC current and a pulsed current.

22. A program according to claim 21, wherein said code for applying said current applies said current to said windings of said spindle motor assembly for an amount of time required for the resistance on a respective one of said windings to reach a predetermined value corresponding to the applied current.

23. A program according to claim 22, wherein said current is applied to said windings of said spindle motor assembly the amount of time required for the resistance on a respective one of said windings to reach a predetermined value based on a table stored in a controller in said DASD.

24. A program according to claim 23, wherein the values of resistance of said windings corresponding to current values stored in said table in said controller are predetermined by measuring changing resistance values in respective ones of said windings in accordance with a change in an amount of current or voltage applied to the respective winding.

25. A program according to claim 21, wherein said current applied to said windings of said spindle motor assembly corresponds to the measured temperature of said DASD in a table stored in a controller of said DASD.

26. A program according to claim 25, wherein said current is applied to said windings for an amount of time required for the bearings of said spindle motor assembly to reach a predetermined minimum threshold temperature.

27. A program for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD), comprising:

a code for measuring a temperature of said DASD;

a code for exciting the phases of said spindle motor assembly for an amount of time required for the temperature of said spindle motor assembly to rise to a minimum threshold temperature for normal operation; and

a code for starting spinning operation of said spindle motor assembly when the temperature of said spindle motor assembly has risen to the minimum threshold temperature for normal operation, wherein exciting said phases of said spindle motor assembly includes rocking said phases back-and-forth in a clockwise-counterclockwise manner at a predetermined rate of speed.

28. A program according to claim 27, wherein said phases of said spindle motor assembly are excited until a bearing assembly of said spindle motor assembly reaches a minimum threshold temperature.

29. A program according to claim 28, wherein said phases of said spindle motor assembly are excited until the grease of said bearing assembly of said spindle motor assembly reaches a minimum threshold temperature.

30. A program according to claim 27, wherein said temperature of said DASD is measured by a thermistor on a card therein.

31. A program according to claim 27, wherein said temperature of said DASD is measured by a thermistor on said spindle motor assembly.

32. A program for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD), comprising:

a code for measuring a temperature of said DASD using a thermistor on said spindle motor assembly;

a code for heating said spindle motor assembly for an amount of time required for the temperature of said spindle motor assembly to rise to a minimum threshold temperature for normal operation; and

a code for starting spinning operation of said spindle motor assembly when the temperature of said spindle motor assembly has risen to the minimum threshold temperature for normal operation.

33. A program according to claim 32, wherein said heat is applied to said spindle motor assembly for an amount of time that corresponds to the measured temperature of said DASD in a table stored in a controller of said DASD.

34. A program according to claim 32, wherein heating said spindle motor assembly includes applying a current thereto for an amount of time required for the bearings of said spindle motor assembly to reach a predetermined minimum threshold temperature.

35. A method for preventing cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD), said method comprising:

measuring a temperature of said DASD;

heating said spindle motor assembly to raise the temperature of said spindle motor assembly to a minimum threshold temperature for normal operation when the measured temperature of said DASD is less than 0°

Celsius;

halting the heating of said spindle motor assembly when said spindle motor assembly has been heated for a time equal to or greater than a predetermined threshold amount of time, applying a current to said spindle motor assembly, measuring the current applied to spindle motor assembly and comparing the measured current to a maximum threshold current,

wherein spinning operation of said spindle motor commences when the measured current is less than the maximum threshold current; and

re-heating said spindle motor assembly when the measured current exceeds the maximum threshold current, re-applying a current to said spindle motor assembly when a measured temperature of the re-heated spindle motor assembly is less than or equal to a maximum threshold temperature, and re-measuring the current re-applied to spindle motor assembly and comparing the re-measured current to the maximum threshold current,

wherein the re-heating ceases and an error report is issued when the re-measured temperature of the re-heated spindle motor assembly is greater than the maximum threshold temperature,

wherein further re-heating of said spindle motor assembly continues when the re-measured current exceeds the maximum threshold current, and said method returns to said re-heating of said spindle motor assembly, and

wherein further re-heating of said spindle motor assembly ceased when the re-measured current exceeds the maximum threshold current, and spinning operation of said spindle motor commences.

36. A processor that is able to prevent cold temperature induced damage to a spindle motor assembly of a direct access storage device (DASD) thereof, a thermistor being disposed on said spindle motor assembly, said processor comprising:

means for measuring a temperature of said DASD using said thermistor;

means for applying a current to windings of said spindle motor assembly for an amount of time required for the temperature of said spindle motor assembly to rise to a minimum threshold temperature for normal operation; and

means for starting spinning operation of said spindle motor assembly when the temperature of said spindle motor assembly has risen to the minimum threshold temperature for normal operation.

37. A processor according to claim 36, wherein said current is any one of a DC current, an AC current and a pulsed current.

38. A processor according to claim 37, wherein said means for applying said current applies said current to said windings of said spindle motor assembly for an amount of time required for the resistance on a respective one of said windings to reach a predetermined value corresponding to the applied current.

39. A processor according to claim 37, wherein said current is applied to said windings of said spindle motor assembly the amount of time required for the resistance on a respective one of said windings to reach a predetermined value based on a table stored in a controller in said DASD.

40. A processor according to claim 39, wherein the values of resistance of said windings corresponding to current values stored in said table in said controller are predetermined by measuring changing resistance values in respective ones of said windings in accordance with a change in an amount of current or voltage applied to the respective winding.

41. A processor according to claim 37, wherein said current applied to said windings of said spindle motor assembly corresponds to the measured temperature of said DASD in a table stored in a controller of said DASD.

42. A processor according to claim 41, wherein said current is applied to said windings for an amount of time required for the bearings of said spindle motor assembly to reach a predetermined minimum threshold temperature.