A relatively unexplored but extremely attractive field for the application of the shape memory technology is the area of rotary actuators, especially for generating continuous rotations. This paper deals with a novel design of a rotary motor based on SMA wires and overrunning clutches which features high output torque and boundless angular stroke in a compact package. The concept uses a long SMA wire wound round a low-friction cylindrical drum upon which the wire can contract and extend with minimum effort and limited space demand. Fitted to the output shaft by means of an overrunning clutch the output shaft rotates unidirectionally despite the sequence of contractions-elongation cycles of the wire. Following a design procedure developed in a former paper, a six-stage miniature prototype is built and tested showing excellent performance in terms of torque, speed and power density. Characteristic performances of the motor are as follows: size envelope = 48×22×30 mm³; maximum torque = 20 Nmm; specific torque = 6.31×10⁻⁴ Nmm/mm3; rotation per module = 15 deg; continuous speed (unloaded) = 4 rpm.

Date Published: 2 April 2015
PDF: 9 pages
Proc. SPIE 9431, Active and Passive Smart Structures and Integrated Systems 2015, 94312K (2 April 2015); doi: 10.1117/12.2081802

Published in SPIE Proceedings Vol. 9431:
Active and Passive Smart Structures and Integrated Systems 2015
Wei-Hsin Liao, Editor(s)