초록 ▼

A rotary actuator which provides a differential pulley pair having a shape memory alloy wire. The shape memory alloy wire is thermally cycled through its phase change transition temperature and contracts. Tension forces applied by the ends of the wires to opposite sides of the pulley pair result in

A rotary actuator which provides a differential pulley pair having a shape memory alloy wire. The shape memory alloy wire is thermally cycled through its phase change transition temperature and contracts. Tension forces applied by the ends of the wires to opposite sides of the pulley pair result in a net torque which causes relative rotation between the pulley pair and a reference base. The large mechanical advantage of the differential pulley converts a large force working through a small distance into a relatively large angular rotation.

대표청구항 ▼

A rotary actuator comprising means forming first and second moment arms which project in generally opposite directions from a common axis, said first moment arm having a radial length r1 and said second moment arm having a radial length r2 which is less than r1 by a predetermined amount, a reference

A rotary actuator comprising means forming first and second moment arms which project in generally opposite directions from a common axis, said first moment arm having a radial length r1 and said second moment arm having a radial length r2 which is less than r1 by a predetermined amount, a reference structure, means mounting said moment arms for conjoint rotation relative to the reference structure about the common axis, an elongate element of shape memory alloy material, means for mounting one end of the element to the outer radial end of the first arm, means for mounting the other end of the element to the outer radial end of the second arm, means for heating the shape memory alloy material of the element through its phase change transition temperature to cause contraction of the length of the element toward its memory shape, and idler means for conducting portions of the shape memory alloy material of the element along a path which extends in a loop from the outer end of the first arm to the outer end of the second arm, said idler means holding the ends of the element under tension forces during contraction of the element with the tension forces applying torques on the respective moment arms whereby the resulting net torque causes relative rotation between the moment arms and reference structure.