Electroactive polymer torsional device

• US 7,378,783 B2
• Filed: 07/12/2007
• Issued: 05/27/2008
• Est. Priority Date: 03/02/2001
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Pelrine, Ronald E., Kornbluh, Roy D., Heim, Jonathan
• Primary Examiner(s): San Martin, Jaydi A
• Application Number:
  US11/777,079
• Publication Number:
  US 20070290577A1
• Time in Patent Office: 320 Days
• Field of Search: 310/328, 310/800
• US Class Current: 310/311
• CPC Class Codes: H02N 2/101 using intermittent driving, e.g. step motors
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

The present invention relates to mechanical-electrical power conversion systems. The systems comprise one or more electroactive polymers that convert between electrical and mechanical energy. When a voltage is applied to electrodes contacting an electroactive polymer, the polymer deflects. This deflection may be converted into rotation of a power shaft included in a motor. Repeated deflection of the polymer may then produce continuous rotation of the power shaft.

Claims

1. A device for converting between electrical energy and mechanical energy, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a first portion of the polymer to deflect in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer;

a first substantially rigid member attached to a second portion of the polymer;

a second substantially rigid member attached to a third portion of the polymer, the second portion and the third portion arranged to change in distance therebetween upon deflection of the first portion; and

a first flexure coupled to the first and second members, wherein the first flexure is configured to improve torsional stiffness for the device.

2. The device of claim 1 further including a second flexure coupled to the first and second members, wherein the second flexure is configured to improve torsional stiffness for the device.

3. The device of claim 1 wherein the first and second substantially rigid members are attached to substantially parallel edges of the polymer and prevent deflection of the polymer in a direction substantially parallel to the substantially parallel edges.

4. The device of claim 1 wherein the first flexure comprises a first flexure member mechanically coupled to a second flexure member, the first flexure member coupled to the first substantially rigid member and the second flexure member coupled to the second substantially rigid member.

5. The device of claim 1 wherein the polymer has a planar aspect ratio greater than 4:

1.

6. The device of claim 1 wherein the first flexure improves torsional stiffness for the device about the plane of the polymer.

7. The device of claim 1 wherein the polymer includes a dielectric elastomer.

8. The device of claim 1 wherein the device is substantially planar.

9. The device of claim 1 wherein the polymer is anisotropically pre-strained.

10. The device of claim 1 wherein the at least two electrodes include a conductive grease or carbon black.

11. A device for converting between electrical energy and mechanical energy, the device comprising:

at least one transducer, each transducer comprising;

at least two electrodes, and

a polymer arranged in a manner which causes a first portion of the polymer to deflect in response to a change in electric field and/or arranged in a manner which causes a change in electric field in response to deflection of the polymer;

a first substantially rigid member attached to a second portion of the polymer;

a second substantially rigid member attached to a third portion of the polymer,

wherein the first and second substantially rigid members are attached to substantially parallel edges of the polymer and prevent deflection of the polymer in a direction substantially parallel to the substantially parallel edges;

a first flexure coupled to the first and second members, wherein the first flexure is configured to improve torsional stiffness for the device; and

a second flexure coupled to the first and second members, wherein the second flexure is configured to improve torsional stiffness for the device.

12. The device of claim 11 wherein the first flexure comprises a first flexure member mechanically coupled to a second flexure member, the first flexure member coupled to the first substantially rigid member and the second flexure member coupled to the second substantially rigid member.

13. The device of claim 11 wherein the polymer has a planar aspect ratio greater than 4:

1.

14. The device of claim 11 wherein the first flexure improves torsional stiffness for the device about the plane of the polymer.

15. The device of claim 11 wherein the polymer includes a dielectric elastomer.

16. The device of claim 11 wherein the device is substantially planar.

17. The device of claim 11 wherein the polymer is anisotropically pre-strained.