Robust design of a shape memory actuator with slider and slot layout and passive cooling control

This work proposes a new shape memory actuator based on a slider and slot mechanism. The device is composed by two couples of opposed SMA coil elements. The SMA elements are heated by means of Joule effect connecting their ends to an electric power supply through special terminal clips. The cooling is realized with an axial air fan. The movement of the slot is realized when both SMA elements of a couple are heated. The electric connection are realized to minimize the wirings connecting a couple of parallel SMA elements in electric series, in this way electric contacts are not needed on the slot, but only in the static part of the device. On the upper side of the static guide, there is the axial cooling fan, and the sliding slot is realized with openings on upper and lower sides to allow the air flow. The actuator exhibits a linear relation between the feeding electric current and the realized mean speed, independently by the applied mechanical load. The generated mean speed is repeatable: the difference between the minimum and the maximum speed for a single condition is less than 1 %. The resulting cooling time is substantially less than those shown in literature with comparable technologies.