Patent ID: 7688168

Claim:
A linear actuator comprising a shaft and an actuator assembly configured to enable relative movement to occur between the shaft and the actuator assembly, the actuator assembly comprising: (a) a member configured to be magnetically actuated, actuation of the member causing the member to move from a first position to a second position, where the second position is closer to a magnetic field than the first position, the member comprising a shape memory alloy, such that when the shape memory alloy moves to the second position, a stress is applied to the shape memory alloy, and that stress, in combination with the shape memory alloy being exposed to a greater magnetic flux by virtue of being closer in proximity to the magnetic field in the second position as compared to the first position, causes a phase change in the shape memory alloy, from an initial relatively stiff austenitic state to a relatively softer martensitic state, the phase change resulting from a hybrid mechanism requiring both an applied stress and an exposure to a sufficiently strong magnetic field; and (b) a magnetic trigger configured to selectively actuate the member, the magnetic trigger controlling the magnetic field associated with the movement of the member to the second position.