Electroactive polymer torsional device

• US 7,705,521 B2
• Filed: 04/23/2008
• Issued: 04/27/2010
• Est. Priority Date: 03/02/2001
• Status: Expired due to Fees

• 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:
  US12/108,324
• Publication Number:
  US 20080252176A1
• Time in Patent Office: 734 Days
• Field of Search: 310/328
• US Class Current: 310/328
• 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 motor comprising:

a power shaft configured to rotate about an axis; and

a crank comprising;

a crank pin,

a crank arm configured to transmit force between the crank pin and the power shaft, and

a first transducer coupled to the crank pin, the transducer comprising a first active area, which includes at least a first portion of an electroactive polymer and at least two first active area electrodes coupled to the first portion of the electroactive polymer, and a support structure coupled to a second portion of the electroactive polymer.

2. The system of claim 1 wherein the power shaft includes a stall position that is maintained with substantially no electrical current to the first active area electrodes.

3. The system of claim 1 further including a connecting rod that interconnects the electroactive polymer and the crank pin.

4. The system of claim 1 wherein a flat plane of the electroactive polymer is substantially perpendicular to the axis.

5. The system of claim 1 further including a second transducer operably coupled to the crank pin.

6. The system of claim 5 wherein the first transducer and the second transducer are arranged in a V about the power shaft, the V having an angle between about 0 degrees and 180 degrees.

7. The system of claim 5 wherein the first transducer and the second transducer are arranged in-line about the power shaft.

8. The system of claim 1 wherein the electroactive polymer is a dielectric elastomer.

9. The system of claim 1 wherein the electroactive polymer includes an elastic modulus less than about 100 MPa.

10. A motor comprising:

a power shaft configured to rotate about an axis; and

a crank comprising;

a crank pin,

a crank arm configured to transmit force between the crank pin and the power shaft, and

a first transducer coupled to the crank pin, the transducer comprising a first active area, which includes at least a first portion of an electroactive polymer and at least two first active area electrodes coupled to the first portion of the electroactive polymer, a second active area comprising at least two second active area electrodes and a second portion of the electroactive polymer coupled to the at least two second active area electrodes, and a support structure coupled to a third portion of the electroactive polymer.

11. The system of claim 10 wherein the power shaft includes a stall position that is maintained with substantially no electrical current to the first active area electrodes and the second active area electrodes.

12. The system of claim 10 further including a connecting rod that interconnects the electroactive polymer and the crank pin.

13. The system of claim 10 wherein a flat plane of the electroactive polymer is substantially perpendicular to the axis.

14. The system of claim 10 wherein the first and second active area electrodes are symmetrically arranged around the power shaft.

15. The system of claim 14 wherein the first and second active area electrodes are arranged radially around the power shaft.

16. The system of claim 10 wherein elastic potential energy stored in the second portion of the electroactive polymer during actuation of the second active area at least partially contributes to deflection of the first portion of the electroactive polymer.

17. The system of claim 10 wherein the electroactive polymer includes an elastic modulus less than about 100 MPa.

18. The system of claim 10 further comprising a mechanism that assists rotation of the power shaft.

19. The system of claim 18 wherein the mechanism is a flywheel.