Apparatus and process for optimizing work from a smart material actuator product

• US 7,564,171 B2
• Filed: 06/20/2005
• Issued: 07/21/2009
• Est. Priority Date: 04/04/2003
• Status: Expired due to Fees

• Current Assignee: Parker-Hannifin Corporation
• Original Assignee: Parker-Hannifin Corporation
• Inventors: Moler, Jeff, Oudshoorn, Mark P, Bugel, John, Thornhill, Keith A
• Primary Examiner(s): Leung; Queyen
• Assistant Examiner(s): Addison; Karen B
• Application Number:
  US11/156,408
• Publication Number:
  US 20050231077A1
• Time in Patent Office: 1,492 Days
• Field of Search: 310/328, 310/311, 310/329, 269/329
• US Class Current: 310/328
• CPC Class Codes: H02N 2/043 Mechanical transmission means, e.g. for stroke amplification
• CPC Class Codes: H10N 30/886 Mechanical prestressing means, e.g. springs springs in general F16F1/00

Abstract

An apparatus and process for preloading an electrically stimulated smart material actuator product to obtain maximum work from the actuator. When a smart material actuator is optimally preloaded certain desirable characteristics become apparent, such as work, operational frequency, hysteresis, repeatability, and overall accuracy. When used in conjunction with a mechanically leveraged actuator structure the smart material actuator can be used to its greatest potential. Since the mechanically leveraged actuator can be based on the maximum work provided by the smart material actuator, certain attributes such as the force, and displacement of total system can be adjusted without loss to system efficiency. Preloading methods and a determination of the optimal preload force are disclosed. Each smart material actuator type has a unique work curve. In the design of an actuator assembly, the process of optimizing uses the unique work curve to optimize the design for the requirements of the particular application. The unique work curve is used by finding the place where the smart material actuator is capable of providing the most work in order to set the optimum preload point accordingly. Different mechanical preload techniques are provided.

Claims

1. An apparatus comprising:

a support structure defining a rigid non-flexing portion and at least one movable arm;

a smart material actuator for driving the at least one movable arm of the support structure between first, second and third positions; and

means for preloading the smart material actuator with a sufficient preload force to optimize work output of the support structure, wherein the means for preloading the smart material actuator applies a non-energized load to the actuator to pivot the at least one movable arm from the first position to the second position.

2. The apparatus of claim 1, wherein work output is defined as a function of displacement and force with infinite life of the support structure.

3. The apparatus of claim 2, wherein the preloading means optimizes work output to an efficiency of between approximately 60% to approximately 90%, inclusive of the work input from the smart material actuator.

4. The apparatus of claim 1, wherein the preloading means optimizes work output to an efficiency of greater than 60%, inclusive of the work input from the smart material actuator.

5. The apparatus of claim 1, wherein the preloading means optimizes work output to an efficiency of between approximately 75% to approximately 90%, inclusive of the work input from the smart material actuator.

6. The apparatus of claim 1, wherein the preloading means optimizes work output to an efficiency of greater than 75%, inclusive of the work input from the smart material actuator.

7. The apparatus of claim 1, wherein the preloading means optimizes work output to an efficiency of greater than 90%, inclusive of the work input from the smart material actuator.

8. The apparatus of claim 1, wherein the preloading means optimizes work output to within 20% of peak load as determined by the force displacement product versus force curve of the work input from the smart material actuator.

9. The apparatus of claim 1, wherein the preloading means is located between the rigid, non-flexing portion of the support structure and the smart material actuator.

10. The apparatus of claim 9, wherein the at least one movable arm comprises two movable arms and the preloading means further comprises:

an adjustable threaded screw positioned between the two movable arms and extending between the rigid, non-flexing portion of the support structure and one end of the smart material actuator.

15. The apparatus of claim 9, wherein the preloading means is located between the rigid, non-flexing portion of the support structure and the moveable portion of the support structure.

19. The apparatus of claim 1, wherein the smart material actuator is a piezoelectric actuator.

20. The apparatus of claim 1, wherein applying an energized load to the actuator pivots the at least one arm from the second position to the third position.

11. An apparatus comprising:

a support structure defining a rigid non-flexing portion and at least one movable arm;

a smart material actuator for driving the at least one movable arm of the support structure between first, second and third positions; and

means for preloading the smart material actuator with a sufficient preload force to optimize work output of the support structure, wherein the preloading means is located between the rigid, non-flexing portion of the support structure and the smart material actuator and wherein the preloading means further comprises;

an adjustable wedge positioned between the rigid, non-flexing portion of the support structure and one end of the smart material actuator.

12. The apparatus of claim 11, wherein the adjustable wedge further comprises:

a first semi-circular wedge portion, a second complementary semi-circular wedge portion, a center wedge portion, and an adjustment screw, such that adjustment of the screw moves the center wedge portion with respect to the first and second semi-circular wedge portions toward and away from one another and adjusts an amount of preload applied to the smart material actuator.

13. The apparatus of claim 11, wherein the adjustable wedge further comprises:

a first longitudinal wedge portion engageable with the rigid, non-flexing portion of the support structure and a second longitudinal wedge portion engageable with one end of the smart material actuator, the first wedge portion having a transversely extending, angled, serrated surface and the second wedge portion having a complementary transversely extending, angled, serrated surface for operable interlocking engagement with the first wedge portion, such that transverse movement, of one wedge portion with respect to the other wedge portion adjusts an amount of preload applied to the smart material actuator.

14. The apparatus of claim 11, wherein the adjustable wedge further comprises:

a first cam surface portion, a second complementary cam surface portion, a cam screw located between the first and second cam surface portions, such that adjustment of the cam screw moves the cam surface portions with respect to the one another and adjusts an amount of preload applied to the smart material actuator.

16. An apparatus comprising:

a support structure defining a rigid non-flexing portion and at least one movable arm;

a smart material actuator for driving the at least one movable arm of the support structure between first, second and third positions; and

means for preloading the smart material actuator with a sufficient preload force to optimize work output of the support structure, wherein the preloading means is located between the rigid, non-flexing portion of the support structure and the smart material actuator and wherein the preloading means further comprises;

the rigid, non-flexing portion of the support structure having a separable, adjustable, rigid, non-flexing web operably engageable with at least one rigid, non-flexing arm of the support structure, such that the adjustment of the web with respect to the at least one arm allows locking engagement between the web and the at least one arm of the support structure at a predetermined preload on the smart material actuator.

17. The apparatus of claim 16, wherein the preloading means further comprises:

the web having a first serrated portion engageable with a complementary second serrated portion formed on the at least one arm for operable interlocking engagement with one another, such that movement of web with respect to the at least one arm adjusts an amount of preload applied to the smart material actuator.

18. The apparatus of claim 16, wherein the preloading means further comprises:

the web having at least one adjustable screw operably engageable within at least one corresponding threaded aperture formed in the at least one arm for operable interlocking engagement with one another, such that adjustment of the screw causes movement of web with respect to the at least one arm and applies preload to the smart material actuator.

21. A process for optimizing preload of a smart material actuator for driving at least one movable arm of a support structure between first, second and third positions comprising the steps of:

measuring deflection of support structure versus force applied during energization and deenergization of a smart material;

evaluating force displacement product versus force to determine a peak value for force displacement product; and

applying a non-energized load to the actuator based on the peak value for force displacement product, thereby preloading the actuator by pivoting the at least one arm from a first position to a second position.

22. The process of claim 21, further comprising the step of:

preloading the smart material actuator to a value at least within 40% of the peak value for force displacement product.

23. The process of claim 21, wherein the preloading step further comprises preloading the smart material actuator to a value at least within 25% of the peak value for force displacement product.

24. The process of claim 21, wherein the preloading step further comprises preloading the smart material actuator to a value at least within 10% of the peak value for force displacement product.

25. The process of claim 21, wherein the preloading step further comprises preloading the smart material actuator to the peak value for force displacement product.

26. The process of claim 21, further comprising the step of:

applying an energized load to the actuator pivoting the at least one arm from the second position to the third position.

27. A product manufactured according to the process of claim 21 further comprising:

a support structure defining a rigid non-flexing portion and at least one movable arm;

a smart material actuator for driving the at least one movable arm of the support structure between first, second and third positions; and

means for preloading the smart material actuator with a sufficient preload force to optimize work output of the support structure, where work output is defined as a function of displacement and force with infinite life of the support structure.

28. The product of claim 27, wherein the preloading means optimizes work output to an efficiency of between approximately 60% to approximately 90%, inclusive of the work input from the smart material actuator.

29. The product of claim 27, wherein the preloading means optimizes work output to an efficiency of greater than 60%, inclusive of the work input from the smart material actuator.

30. The product of claim 27, wherein the preloading means optimizes work output to an efficiency of between approximately 75% to approximately 90%, inclusive of the work input from the smart material actuator.

31. The product of claim 27, wherein the preloading means optimizes work output to an efficiency of greater than 75%, inclusive of the work input from the smart material actuator.

32. The product of claim 27, wherein the preloading means optimizes work output to an efficiency of greater than 90%, inclusive of the work input from the smart material actuator.

33. The product of claim 27, wherein the preloading means optimizes work output to within 20% of peak load as determined by the force displacement product versus force curve of the work input from the smart material actuator.

34. The product of claim 27, wherein the preloading means is located between the rigid, non-flexing portion of the support structure and the smart material actuator.

35. The product of claim 34, wherein the preloading means further comprises:

an adjustable threaded screw extending between the rigid, non-flexing portion of the support structure and one end of the smart material actuator.

36. The product of claim 34, wherein the preloading means further comprises:

an adjustable wedge positioned between the rigid, non-flexing portion of the support structure and one end of the smart material actuator.

37. The product of claim 36, wherein the adjustable wedge further comprises:

a first semi-circular wedge portion, a second complementary semi-circular wedge portion, a center wedge portion, and an adjustment screw, such that adjustment of the screw moves the center wedge portion with respect to the first and second semicircular wedge portions toward and away from one another and adjusts an amount of preload applied to the smart material actuator.

38. The product of claim 36, wherein the adjustable wedge further comprises:

a first longitudinal wedge portion engageable with the rigid, non-flexing portion of the support structure and a second longitudinal wedge portion engageable with one end of the smart material actuator, the first wedge portion having a transversely extending, angled, serrated surface and the second wedge portion having a complementary transversely extending, angled, serrated surface for operable interlocking engagement with the first wedge portion, such that transverse movement of one wedge portion with respect to the other wedge portion adjusts an amount of preload applied to the smart material actuator.

39. The product of claim 36, wherein the adjustable wedge further comprises:

a first cam surface portion, a second complementary cam surface portion, a cam screw located between the first and second cam surface portions, such that adjustment of the cam screw moves the cam surface portions with respect to the one another and adjusts an amount of preload applied to the smart material actuator.

40. The product of claim 34, wherein the preloading means is located between the rigid, non-flexing portion of the support structure and the movable portion of the support structure.

41. The product of claim 40, wherein the preloading means further comprises:

the rigid, non-flexing portion of the support structure having a separable, adjustable, rigid, non-flexing web operably engageable with at least one rigid, non-flexing arm of the support structure, such that the adjustment of the web with respect to the at least one arm allows locking engagement between the web and the at least one arm of the support structure at a predetermined preload on the smart material actuator.

42. The product of claim 41, wherein the preloading means further comprises:

the web having a first serrated portion engageable with a complementary second serrated portion formed on the at least one arm for operable interlocking engagement with one another, such that movement of web with respect to the at least one arm adjusts an amount of preload applied to the smart material actuator.

43. The product of claim 41, wherein the preloading means further comprises:

the web having at least one adjustable screw operably engageable within at least one corresponding threaded aperture formed in the at least one arm for operable interlocking engagement with one another, such that adjustment of the screw causes movement of web with respect to the at least one arm and applies preload to the smart material actuator.

44. The product of claim 27, wherein the smart material actuator is a piezoelectric actuator.