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US 6,499,952 B1Granted
Shape memory alloy device and control method
AssigneeThe Boeing Company
InventorsA. Dean Jacot, Robert T. Ruggeri, Dan J. Clingman
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AssigneeThe Boeing Company
InventorsA. Dean Jacot, Robert T. Ruggeri, Dan J. Clingman
Estimating the term…
A preferred rotary actuator includes an actuator assembly having a torque tube formed of a shape memory alloy (SMA), a superelastic NiTinol return spring associated with the torque tube and adapted to bias the torque tube toward an initial position, and a torque tube heating element, especially a thermoelectric device, for switching the SMA to cause rotation to an object connected to the actuator or to generate a torque upon that object. The torque tube (24) includes a proximal end (32) and a distal end (34). The return spring and torque tube are connected at their ends, with the torque tube being pretwisted while in a martensitic state relative to the spring. Activation of the heating element causes the torque tube to enter an austenitic state in which it returns to its previous untwisted configuration. Removal of heat allows the torque tube to return to a martensitic state, when the return spring retwists the torque tube. A unique locking assembly 22 is used with the preferred actuator assembly. A helicopter blade twist rotation system for a rotorcraft blade 200 having a blade root 202 and a tip 204 includes a SMA rotary actuator 18 located within the blade near the blade root, and a passive torque tube (206) located within the blade and having a proximal end connected to the rotary actuator and a distal end connected to the blade near to the blade tip.
A rotary actuator, comprising:
A helicopter blade twist rotation system for use with a helicopter blade having a blade root end, a blade tip end, and a longitudinal spar extending from the blade root end toward the blade tip, the system comprising:
A method for switching a shape memory alloy (SMA) device between two states, namely a first state and a second state, comprising the steps of (a) heating the alloy with at least one thermoelectric device connected to a heat sink to conduct heat from the heat sink to the alloy to cause the alloy to switch from the first state to the second state, wherein the heat sink is a SMA torque tube arranged for antagonistic function with the alloy and (b) cooling the alloy to return the alloy to the first state when the thermoelectric device switches to conduct heat from the torque tube to the alloy.
A method for switching a shape memory alloy (SMA) device between two states, namely a first state and a second state, comprising heating the alloy with at least one thermoelectric device connected to an internal heat sink to conduct heat from the internal heat sink to the alloy to cause the alloy to switch from the first state to the second state, wherein the internal heat sink is a SMA torque tube arranged for antagonistic function with the shape memory alloy to return the alloy to the first state when the thermoelectric device conducts heat from the torque tube to the alloy, further comprising another thermoelectric device for controlling heat flow from the device and the SMA torque tube to an external heat sink.
In combination, at least two shape memory alloy devices, each adapted for switching between two states under the control of and associated with at least one thermoelectric device in proximity with both devices to provide heating to a first device while cooling the second device to achieve switching of both devices between their states.
A method for changing blade twist in a rotocraft blade, comprising the step of switching a shape memory alloy actuator by controlling the temperature of the actuator with a thermoelectric device to change the blade twist in the rotocraft blade.
A rotary actuator comprising:
A rotary actuator, comprising:
Dependencies are inferred from the claim text.