Energy converters and associated methods

• US 7,893,599 B2
• Filed: 01/29/2009
• Issued: 02/22/2011
• Est. Priority Date: 01/29/2008
• Status: Expired due to Fees

• Current Assignee: Washington State University
• Original Assignee: Washington State University
• Inventors: Youngsman, John M., Morris, Dylan J., Anderson, Michael J., Bahr, David F.
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US12/362,125
• Publication Number:
  US 20090200896A1
• Time in Patent Office: 754 Days
• Field of Search: 310/329, 310/339, 310/800
• US Class Current: 310/339
• CPC Class Codes: H02N 2/188 adapted for resonant operation
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

Energy converters and associated methods are disclosed herein. In one embodiment, an energy converter includes a first structural member spaced apart from a second structure member, a first piezoelectric element and a second piezoelectric element individually coupled to the first structural member and the second structural member, and a deflection member tensionally suspended between the first and second piezoelectric elements. The deflection member is substantially rigid.

Claims

1. A device for converting mechanical vibration energy to electrical energy, comprising:

a first structural member;

a second structural member spaced apart from the first structural member;

a first piezoelectric element and a second piezoelectric element individually coupled to the first structural member and the second structural member; and

a deflection member tensionally suspended between the first and second piezoelectric elements, the deflection member being substantially rigid, wherein the deflection member is adjustable at least in length along a direction of deflection with respect to the first and second piezoelectric elements.

2. The device of claim 1 wherein the first and second piezoelectric elements are generally identical to each other, and wherein the first and second piezoelectric elements are arranged generally symmetrically relative to the deflection member.

3. The device of claim 1 wherein the first and second piezoelectric elements are at least partially flexible such that the deflection member deflects the first and second piezoelectric elements away from each other.

4. The device of claim 1 wherein the first and second piezoelectric elements are at least partially flexible such that the deflection member deflects the first piezoelectric element in a first direction, and wherein the deflection member deflects the second piezoelectric element in a second direction generally opposite of the first direction.

5. The device of claim 1 wherein the device has a natural frequency linearly related to a degree of deflection of the first or second piezoelectric element.

6. The device of claim 1 wherein the deflection member is adjustable with respect to the first and second piezoelectric elements.

7. A device for converting mechanical vibration energy to electrical energy, comprising:

a first structural member;

a second structural member spaced apart from the first structural member;

a first piezoelectric element and a second piezoelectric element individually coupled to the first structural member and the second structural member; and

a deflection member tensionally suspended between the first and second piezoelectric elements, the deflection member being substantially rigid, wherein the deflection member is adjustable with respect to the first and second piezoelectric elements, and wherein the device further includes an adjustment member operatively coupled to the deflection member, the adjustment member being configured to adjust a degree of deflection with respect to the first and second piezoelectric elements.

8. An energy converter, comprising:

a first end member and a second end member spaced apart from the first end member;

a first conversion element coupled to the first end member;

a second conversion element coupled to the second end member, at least one of the first and second conversion elements is at least partially deformable and is configured to convert mechanical energy to electrical energy; and

a mass between the first and second conversion elements, at least one of the first end member, the second end member, and the mass applying a static tension to at least one of the first and second conversion elements, wherein the mass is adjustable at least in length along a direction of deflection with respect to the first and second conversion elements.

9. The energy converter of claim 8 wherein the first and second conversion elements extend between the first and second end members in the longitudinal direction, and wherein the mass is located generally in a center position along the longitudinal direction.

10. The energy converter of claim 8 wherein the first and second conversion elements extend between the first and second end members in the longitudinal direction, and wherein the mass stretches at least one of the first and second conversion elements in a transverse direction.

11. The energy converter of claim 8 wherein the first and second conversion elements extend between the first and second end members in the longitudinal direction, and wherein at least one of the mass and the first and second end members stretch at least one of the first and second conversion in the longitudinal direction.

12. The energy converter of claim 8 wherein the first and second conversion elements extend between the first and second end members in a longitudinal direction, and wherein the mass is located generally in a center position along the longitudinal direction, and further wherein the mass stretches at least one of the first and second conversion in a transverse direction.

13. The energy converter of claim 8 wherein the first and second conversion elements individually include a generally circular diaphragm that is at least partially deformable.

14. The energy converter of claim 8 wherein the energy converter further includes an adjustment member operatively coupled to at least one of the first and second end members, the adjustment member being configured to modulate a distance between the first and second end members.

15. The energy converter of claim 8 wherein the first and second conversion elements include circular diaphragms that extend between the first and second end members in a longitudinal direction, and wherein the energy converter further includes a screw operatively coupled to the first and second end members, the screw being configured to modulate a distance between the first and second end members in the longitudinal direction.

16. A method for energy conversion, comprising:

receiving a vibration from an environment with a energy converter, the energy converter including a substantially rigid mass that pretensions a piezoelectric element;

adjusting a natural frequency of the energy converter by modulating a degree of pretension on the piezoelectric element;

converting the received vibration from the environment into at least one of electric energy, optic energy, sound energy, and electromagnetic energy;

detecting a power output from the energy converter; and

wherein adjusting a natural frequency of the energy converter includes modulating a degree of pretension on the piezoelectric element based on the power output from the energy converter.

17. The method of claim 16 wherein adjusting a natural frequency of the energy converter includes adjusting a natural frequency of the energy converter based on a frequency of the vibration from the environment.

18. The method of claim 16, further comprising:

detecting a frequency of the vibration from the environment; and

wherein adjusting a natural frequency of the energy converter includes adjusting a natural frequency of the energy converter by modulating a degree of pretension on the piezoelectric element to generally match the detected frequency of the vibration from the environment.

19. A method for energy conversion, comprising:

receiving a vibration from an environment with a energy converter, the energy converter including a substantially rigid mass that pretensions a piezoelectric element;

adjusting a natural frequency of the energy converter by modulating a degree of pretension on the piezoelectric element;

converting the received vibration from the environment into at least one of electric energy, optic energy, sound energy, and electromagnetic energy;

detecting a power output from the energy converter; and

wherein adjusting a natural frequency of the energy converter includes adjusting a natural frequency of the energy converter by modulating a degree of pretension on the piezoelectric element to at least increase the power output from the energy converter.

20. An energy converter, comprising:

a first structural member and a second structure member spaced apart from the first structural member;

at least one piezoelectric element coupled to the first and second structural members, the piezoelectric element and the first and second structural members at least partially define a natural frequency of the energy converter; and

means for at least partially linearizing a relationship between the natural frequency of the energy converter and a vibration amplitude of the piezoelectric element, wherein means for at least partially linearizing include means for pretensioning the piezoelectric element during a non-energized state, and wherein the energy converter further includes means for adjusting pretension of the piezoelectric element.