Intrinsic monitoring of shape memory alloy actuated devices

• Main Authors: JOHNSON NANCY L, MANKAME NILESH D, ALEXANDER PAUL W, GAO XIUJIE, MCKNIGHT GEOFFREY P, HERRERA GUILLERMO A, BROWNE ALAN L
• Format: Patent
• Language: English
• Published: 23.02.2016
• Subjects: BLASTING; HEATING; LIGHTING; MACHINES OR ENGINES FOR LIQUIDS; MECHANICAL ENGINEERING; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOTOTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISEPROVIDED FOR; OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR; PRODUCING MECHANICAL POWER; SPRING, WEIGHT, INERTIA OR LIKE MOTORS; WEAPONS; WIND, SPRING WEIGHT AND MISCELLANEOUS MOTORS

Some on-vehicle devices, such as air dams, air spoilers, and HVAC system baffles, may have movable components that are pulled from one position to another by shrinkage of a linear shape memory alloy (SMA) actuator. Upon an activation signal, the shrinkage of the SMA actuator occurs when it is resistance heated by an electrical current. It is found that useful information concerning the overall intended operation of the on-vehicle device may be obtained by computer analysis of the temporal variation of both current flow through the actuator and its electrical resistance as it is heated to perform its function in the device. A comparison of present current flow and variation of resistance, during activation of the device, with prescribed stored values can reveal malfunction of components of the device as it is being used, in place, on the vehicle.