BigPatents India

A shape memory alloy actuator comprising a body 30 arranged displaceable between a first and a second position, releasable holding means 47, 48 adapted for holding the body in the first position, a first wire 31 and a second wire 49 made of a shape memory alloy such as nitinol, the first wire being at one end connected to the body such that shortening of the length of the first wire exerts a force on the body for moving it from the second position to the first position, a tension spring 43 for biasing the body for moving it from the first to the second position, the second wire having one end connected to the holding means such that shortening of the length of the second wire releases the holding means for allowing the spring to move the body from the first position to said second position, and the actuator further comprising an intermediate two-armed lever 32 having the end of one arm attached to the tension spring 43 and the end of the other arm 39 abutting a projection 40 on the body 30 such that the force of the spring 43 is transmitted to the body by the lever 32.