Electroactive polymer motors

• US 7,456,549 B2
• Filed: 01/24/2006
• Issued: 11/25/2008
• Est. Priority Date: 03/02/2001
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Kornbluh, Roy D., Eckerle, Joseph Stephen, Heim, Jon, Pelrine, Ronald E.
• Primary Examiner(s): DOUGHERTY, THOMAS M
• Assistant Examiner(s): Addison, Karen
• Application Number:
  US11/339,075
• Publication Number:
  US 20060119225A1
• Time in Patent Office: 1,036 Days
• Field of Search: 310/800, 310/328, 310330-332, 310/339, 310/366, 310/333, 310/311, 310/323.02
• 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 mechanical-electrical power conversion system comprising:

a power shaft configured to rotate about an axis; and

at least one transducer mechanically coupled to the power shaft, the at least one transducer comprising

a first active area, which includes a first portion of at least one electroactive polymer and two first active area electrodes coupled to the first portion of the at least one electroactive polymer, and

a second active area, which includes a second portion of the at least one electroactive polymer and two second active area electrodes coupled to the second portion of the at least one electroactive polymer.

2. The system of claim 1 wherein the at least one transducer is a monolithic transducer that includes both the first active area and the second active area on a single electroactive polymer.

3. The system of claim 2 wherein elasticity of the first and second active areas is substantially balanced about power shaft.

4. 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 and the second active area electrodes.

5. The system of claim 1 wherein the at least one transducer is mechanically coupled to the power shaft using a crank having a crank pin and a crank arm that transmits force between the crank pin and the power shaft.

6. The system of claim 5 wherein the at least one transducer includes an actuator.

7. The system of claim 6 wherein the actuator applies translational motion to the crank pin, which in turn rotates the power shaft to provide power output thereon.

8. The system of claim 5 wherein deflection of the first active area and the second active area along a path provided by the crank arm is substantially independent of elastic potential energy of the at least one transducer.

9. The system of claim 1 wherein the at least one transducer includes a second transducer that includes a second electroactive polymer that includes the second active area.

10. The system of claim 9 wherein elasticity of a first electroactive polymer and elasticity of the second electroactive polymer are balanced about power shaft.

11. The system of claim 9 wherein the first electroactive polymer and the second electroactive polymer are both monolithic electroactive polymers each having multiple active areas.

12. The system of claim 11 wherein the active areas of the first monolithic transducer are offset from the active areas of the second monolithic transducer.

13. The system of claim 1 wherein the system is arranged such that elastic potential energy stored in the second portion of the at least one electroactive polymer during actuation of the second active area at least partially contributes to deflection of the first portion of the at least one electroactive polymer when the first active area is actuated using the first active area electrodes.

14. The system of claim 1 wherein the first and second active areas are symmetrically arranged about the power shaft.

15. The system of claim 1 further comprising a support structure for securing the at least one transducer and for directing a mechanical output derived from the at least one transducer.

16. The system of claim 15 wherein the support structure includes a substantially rigid frame.

17. The system of claim 1 wherein the at least one electroactive polymer has an elastic modulus at most about 100 MPa.

18. The system of claim 1 wherein the at least one electroactive polymer is pre-strained by a factor in the range of about 1.5 to about 50 times an original area of the at least one electroactive polymer prior to the pre-strain.

19. A mechanical-electrical power conversion system comprising:

a power shaft configured to rotate about an axis; and

at least one transducer mechanically coupled to the power shaft, the at least one transducer comprising

a first active area, which includes a first portion of at least one electroactive polymer and first active area electrodes coupled to the first portion of the at least one electroactive polymer, and

a second active area, which includes a second portion of the at least one electroactive polymer and two second active area electrodes coupled to the second portion of the at least one electroactive polymer,

wherein the system is arranged such that elastic potential energy stored in the second portion of the at least one electroactive polymer during actuation of the second active area at least partially contributes to deflection of the first portion of the at least one electroactive polymer when the first active area is actuated using the two first active area electrodes.

20. The system of claim 19 wherein the at least one transducer is a monolithic transducer that includes both the first active area and the second active area on a single electroactive polymer.