Back to results
US 9,316,212 B2Granted
Superelastic shape memory alloy overloading and overheating protection mechanism
AssigneeGM Global Technology Operations LLC
InventorsAlan L. Browne, Nancy L. Johnson
Life of this patent
Estimating the term…
Abstract
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.
Claims16
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;
- and
- is 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;
- and
- is 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;
- and
- the solid state transformation further enables the shape memory alloy actuator to open the circuit, so as to deactivate the shape memory alloy actuator.
16 more elements
An actuation assembly adapted for driving a load and for protecting against an overload condition, said assembly comprising:
- a shape memory alloy actuator to produce an actuating force and stroke when activated, and the shape memory alloy actuator composing a circuit, wherein the circuit, when closed, is to activate the shape memory alloy actuator;
- and
- an overload and overheating protection device including an austenitic shape memory alloy wire:
- having an austenitic finish temperature less than a lowest operating temperature of the shape memory alloy actuator;
- distinct from the shape memory alloy actuator;
- 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 wire;
- connected in series to the shape memory alloy actuator, configured such that the transforming force is caused by the overload condition;
- and
- communicatively coupled to the circuit;
- said solid state transformation enabling the actuating force to cause tensile strain in the austenitic shape memory alloy wire, so as to produce a secondary work output path for the shape memory alloy actuator;
- and
- said tensile strain being further operable to open the circuit, so as to deactivate the shape memory alloy actuator.
9 more elements
An actuation assembly adapted for driving a load and for protecting against an overload condition, said assembly comprising:
- an actuator producing an actuating force and stroke when activated, and composing a circuit, wherein the circuit, when closed, activates the actuator;
- an overload and overheating protection device including an austenitic shape memory alloy wire operable to undergo a change in fundamental property when exposed to or occluded from a stress activation signal, connected in series to the actuator, configured such that the stress activation signal is caused by the overload condition, and communicatively coupled to the circuit;
- said change enabling the actuating force to strain the austenitic shape memory alloy wire, so as to produce a secondary work output path for the actuator;
- and
- said change being further operable to open or close the circuit, so as to deactivate the actuator;
- wherein the overload and overheating protection device is adjustable so as to modify the stress activation signal;
- and
- wherein the overload and overheating protection device further includes a lever defining a pivot axis and a plurality of holes spaced differing distances from the pivot axis, and each hole is configured to removably receive the austenitic shape memory alloy wire.
5 more elements
An actuation assembly adapted for driving a load and for protecting against an overload condition, said assembly comprising:
- an actuator producing an actuating force and stroke when activated, and composing a circuit, wherein the circuit, when closed, activates the actuator;
- and
- an overload and overheating protection device including an austenitic shape memory alloy wire operable to undergo a change in fundamental property when exposed to or occluded from a stress activation signal, connected in series to the actuator, configured such that the stress activation signal is caused by the overload condition, and communicatively coupled to the circuit;
- said change enabling the actuating force to cause tensile strain in the austenitic shape memory alloy wire, so as to produce a secondary work output path for the actuator;
- said change being further operable to open the circuit, so as to deactivate the actuator;
- wherein the overload and overheating protection device is adjustable so as to modify an overload protection threshold for enabling the actuating force to strain the austenitic shape memory alloy wire;
- and wherein the overload and overheating protection device further includes a lever defining a pivot axis and a plurality of holes spaced differing distances from the pivot axis, and each hole is configured to removably receive the austenitic shape memory alloy wire.
4 more elements
Dependencies are inferred from the claim text.