Development of an actuator using a metal hydride and its application to a lifter for the disabled

Metal hydrides can absorb and desorb hydrogen in a reversible reaction by heating or cooling the hydrides, respectively. We have developed an actuator consisting of metal hydrides covered with a copper case (diameter 23 mm, height 6 mm), Peltier elements (38 mm x 38 mm x 5 mm) to heat or cool the hydrides, and a cylinder (diameter 46 mm, height 73 mm) with metal bellows. From the experimental results, it was found that the velocity of hydrogen absorption was faster than the desorption; however, its velocity increased as the weight of the load on the cylinder increased. The actuator could produce a one stroke displacement of 25 mm within 50 s in the case of a 22.5 kg load weight. Furthermore, a double acting type metal hydride actuator composed of a hydraulic cylinder, Peltier elements, and metal hydrides was developed and applied to a lifter for the disabled.