ENERGY CONVERTERS AND ASSOCIATED METHODS

• US 20110156533A1
• Filed: 02/18/2011
• Published: 06/30/2011
• Est. Priority Date: 01/29/2008
• Status: Active Grant

• Current Assignee: Washington State University
• Original Assignee: Washington State University
• Inventors: Youngsman, John M., Morris, Dylan J., Anderson, Michael J., Bahr, David F.
• Granted Patent: US 8,358,049 B2
• Time in Patent Office: Days
• US Class Current: 310/323.01
• 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 between mechanical vibration energy and 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 extending between the first structural member and the second structural member; and

a deflection member suspended between the first and second piezoelectric elements, wherein the first and second piezoelectric elements are under tension from the deflection member and the first and second structural members, the tension having a value corresponding to a target resonance frequency of 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 tension of the first and second piezoelectric elements are adjustable based on the target resonance frequency.

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, and wherein the tension of the first and second piezoelectric elements are dynamically adjustable.

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 a distance between the first and second piezoelectric elements is adjustable.

7. 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, and wherein the tension has a value corresponding to a target resonance frequency of the first and second conversion elements.

8. The energy converter of claim 7 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.

9. The energy converter of claim 7 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.

10. The energy converter of claim 7 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.

11. The energy converter of claim 7 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.

12. The energy converter of claim 7 wherein the first and second conversion elements individually include a generally circular diaphragm that is at least partially deformable.

13. A method for energy conversion, comprising:

receiving a vibration from an environment with an energy converter, the energy converter including a substantially rigid mass that pretensions a piezoelectric element, a degree of pretension on the piezoelectric element corresponding to a target resonance frequency for the energy converter; and

converting the received vibration from the environment into electric energy with the energy converter having the target resonance frequency.

14. The method of claim 13 wherein the target resonance frequency of the energy converter corresponds to a frequency of the vibration from the environment.

15. The method of claim 13, further comprising:

detecting a frequency of the vibration from the environment; and

wherein the degree of pretension on the piezoelectric element causes the energy converter to have a resonance frequency that generally matches the detected frequency of the vibration from the environment.

16. An energy converter, comprising:

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

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

means for adjusting a degree of the pretension based on a target resonance frequency for the energy converter.

17. The energy converter of claim 16 wherein means for adjusting a degree of the pretension include means for adjusting a degree of the pretension based on a target resonance frequency for the energy converter during a non-energized state.

18. The energy converter of claim 16 wherein means for adjusting a degree of the pretension include means for dynamically adjusting a degree of the pretension based on a target resonance frequency for the energy converter.