Pump having shape memory actuator and fuel cell system including the same

• US 20040197214A1
• Filed: 04/07/2003
• Published: 10/07/2004
• Est. Priority Date: 04/07/2003
• Status: Active Grant

• Current Assignee: Intelligent Energy Limited (Lb-shell Plc)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Arthur, Alan R., Watts, Gary J.
• Granted Patent: US 7,198,474 B2
• Time in Patent Office: Days
• US Class Current: 417/413.2
• CPC Class Codes: F03G 7/065 using a shape memory element
• CPC Class Codes: F04B 43/026 each plate-like pumping flexible member working in its own pumping chamber
• CPC Class Codes: F04B 9/00 Piston machines or pumps characterised by the driving or driven means to or from their working members
• CPC Class Codes: F05C 2251/08 Shape memory
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 8/04201 Reactant storage and supply, e.g. means for feeding, pipes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A pump having a shape memory actuator and a fuel cell system including the same.

Claims

1. A pump, comprising:

a movable structure configured to impart motion to a fluid;

a linearly movable shaft operably connected to the movable structure;

a rotatable hub operably connected to the linearly movable shaft such that rotation of the rotatable hub moves the linearly movable shaft linearly; and

a shape memory actuator that rotates the hub when actuated.

2. A pump as claimed in claim 1, wherein the movable structure comprises a diaphragm.

3. A pump as claimed in claim 1, wherein the linearly movable shaft defines first and second longitudinal ends and the movable structure comprises a first and second diaphragms respectively carried by the first and second longitudinal ends of the linearly movable shaft.

4. A pump as claimed in claim 1, wherein the linearly movable shaft and rotatable hub are connected by a planetary gear arrangement.

5. A pump as claimed in claim 1, wherein the shape memory actuator includes a wire formed from shape memory material wrapped around the rotatable hub.

6. A pump as claimed in claim 5, wherein the shape memory actuator includes means for heating the wire to a temperature at which reaches an austenitic phase.

7. A pump as claimed in claim 1, wherein the shape memory actuator includes first and second wires formed from shape memory material wrapped around the rotatable hub.

8. A pump as claimed in claim 7, wherein the shape memory actuator includes a voltage source that applies a voltage across the first and second wires.

9. A pump as claimed in claim 1, wherein the shape memory actuator rotates the rotatable hub in a first direction when actuated, the pump further comprising:

a bias element that biases the hub in a second direction.

10. A pump as claimed in claim 1, wherein the bias element comprises a spring associated with the rotatable hub.

11. A pump, comprising:

a movable structure configured to impart motion to a fluid;

a hub operably connected to the movable structure such that rotation of the hub results in movement of the movable structure, the hub being rotatable in a first direction and a second direction;

a biasing device, operably connected to the rotatable hub, that applies a biasing force in the first direction to the hub; and

shape memory material, operably connected to the rotatable hub, that is configured to stretch in the first direction under the biasing force when in a martensite phase, and to recover strain and rotate the hub in the second direction when in an austenite phase.

12. A pump as claimed in claim 11, wherein the movable structure comprises a diaphragm.

13. A pump as claimed in claim 11, wherein the first direction is clockwise.

14. A pump as claimed in claim 11, wherein the biasing device comprises a spring.

15. A pump as claimed in claim 11, further comprising:

a linearly movable structure that operably connects the biasing device to the rotatable hub.

16. A method of operating a pump having a device that imparts motion to a fluid when moving and a rotatable structure connected to the device such that rotation of the movable structure results in movement of the device, the method comprising the steps of:

applying a force in a first direction to the rotatable structure with a passive device;

energizing a shape memory system;

rotating the rotatable structure in a second direction with the energized shape memory system;

de-energizing the shape memory system;

rotating the rotatable structure in the first direction with the passive device.

17. A method as claimed in claim 16, wherein the step of applying a force in a first direction to the rotatable structure with a passive device comprises applying a force in a first direction to the rotatable structure with a spring.

18. A method as claimed in claim 16, wherein the step of energizing a shape memory system comprises heating a shape memory material.

19. A method as claimed in claim 16, wherein the step of energizing a shape memory system comprises applying a voltage across a shape memory material.

20. A method as claimed in claim 16, wherein the step of rotating the rotatable structure in the first direction with the passive device comprises stretching at least a portion of the shape memory system.

21. A pump, comprising:

a movable structure configured to impart motion to a fluid when moving;

a hub operably connected to the movable structure such that rotation of the hub results in movement of the movable structure, the hub being rotatable in a first direction and a second direction;

means for applying a constant biasing force in the first direction to the hub; and

means for selectively overcoming the constant biasing force to rotate the hub in the second direction.

22. A pump as claimed in claim 21, wherein the movable structure comprises a diaphragm.

23. A pump as claimed in claim 21, wherein the first direction is clockwise.

24. A pump as claimed in claim 21, further comprising:

a linearly movable structure that operably connects the hub to the means for applying a constant biasing force in the first direction to the hub.

25. A fuel cell system, comprising:

a fuel cell; and

a pump, operably connected to the fuel cell, including

a movable structure configured to impart motion to a fluid,

a linearly movable shaft operably connected to the movable structure,

a rotatable hub operably connected to the linearly movable shaft such that rotation of the rotatable hub moves the linearly movable shaft linearly, and

a shape memory actuator that rotates the hub when actuated.

26. A fuel cell system as claimed in claim 25, wherein the fuel cell comprises a PEM fuel cell.

27. A fuel cell system as claimed in claim 25, wherein the movable structure comprises a diaphragm.

28. A fuel cell system as claimed in claim 25, wherein the linearly movable shaft and rotatable hub are connected by a planetary gear arrangement.

29. A fuel cell system as claimed in claim 25, wherein the shape memory actuator includes a wire formed from shape memory material wrapped around the rotatable hub.

30. A fuel cell system as claimed in claim 29, wherein the shape memory actuator includes means for heating the wire to a temperature at which reaches an austenitic phase.

31. A fuel cell system as claimed in claim 25, wherein the shape memory actuator rotates the rotatable hub in a first direction when actuated, the pump further comprising:

a bias element that biases the hub in a second direction.

32. A fuel cell system as claimed in claim 25, wherein the bias element comprises a spring associated with the rotatable hub.

33. A system, comprising:

a fuel consuming device;

a fuel cell operably connected to the fuel consuming device; and

a pump, operably connected to the fuel cell, including a movable structure configured to impart motion to a fluid,

a linearly movable shaft operably connected to the movable structure,

a rotatable hub operably connected to the linearly movable shaft such that rotation of the rotatable hub moves the linearly movable shaft linearly, and

a shape memory actuator that rotates the hub when actuated.

34. A system as claimed in claim 33, wherein the fuel cell comprises a PEM fuel cell.

35. A system as claimed in claim 33, wherein the movable structure comprises a diaphragm.

36. A system as claimed in claim 33, wherein the linearly movable shaft and rotatable hub are connected by a planetary gear arrangement.

37. A system as claimed in claim 33, wherein the shape memory actuator includes a wire formed from shape memory material wrapped around the rotatable hub.

38. A system as claimed in claim 37, wherein the shape memory actuator includes means for heating the wire to a temperature at which reaches an austenitic phase.

39. A system as claimed in claim 33, wherein the shape memory actuator rotates the rotatable hub in a first direction when actuated, the pump further comprising:

a bias element that biases the hub in a second direction.

40. A system as claimed in claim 33, wherein the bias element comprises a spring associated with the rotatable hub.