Superelastic shape memory alloy overloading and overheating protection mechanism

摘要

An actuation assembly adapted for driving a load and protecting against overloading and overheating conditions, includes an actuator defining a stroke when exposed to an activation signal, and further includes a protection device comprising a superelastic shape memory alloy element connected in series to and cooperatively configured with the actuator, and operable to both produce a secondary work output path for the actuator and discontinue the signal.

主权项

1. An overload and overheating protection device, comprising:
an austenitic shape memory alloy protection element operable to undergo a solid state transformation from an austenitic phase having a first modulus to a de-twinned martensitic phase having a second modulus smaller than the first modulus when a transforming force is applied to the austenitic shape memory alloy protection element; wherein:
the austenitic shape memory alloy protection element:
is adapted for use with a shape memory alloy actuator and for protecting the shape memory alloy actuator from an overload condition of the shape memory alloy actuator;has an austenitic finish temperature less than a lowest operating temperature of the shape memory alloy actuator; andis communicatively coupled to an electrical circuit;the shape memory alloy actuator:
is distinct from the austenitic shape memory alloy protection element;is drivenly coupled to a load;defines a stroke;produces an actuating force when activated;is an element of the electrical circuit; andis activated by closing the electrical circuit;the transforming force is caused by the overload condition of the shape memory alloy actuator;the solid state transformation enables the actuating force to cause tensile strain in the austenitic shape memory alloy protection element, so as to produce a secondary work output path for the shape memory alloy actuator; andthe solid state transformation further enables the shape memory alloy actuator to open the circuit, so as to deactivate the shape memory alloy actuator.