Shape memory alloy actuators (SMA), thermostatic switch
This invention describes a way to decrease the temperature difference required for the SMA wire to fully actuate. The SMA wire actuates when it is heated from A
s (Austenite Start Temperature) to A f (Austenite Finish Temperature), which are both dependent on the stress applied to the wire. Higher stress increases both A s and A f, while lower stress decreases both. A negative differential spring displaced can decrease the As-Af temperature difference.
US Provisional Patent Application 61/569447 filed 12/12/2011
Last revised: April 4, 2012