摘要:
A method of controlling a shape memory alloy actuator utilizing the change in resistance exhibited by the actuator over an actuation cycle, or a derivative thereof, to identify at least one event, such as, for example, a peak, valley, change in slope without reaching a valley, or a jump in resistance within the signal plot that corresponds to the start of actuation, end of actuation, an overload case, and the introduction of a resistive element respectively, and generating a response based upon the event.
摘要:
An energy harvesting system comprises a first region and a second region having a temperature difference therebetween. A heat engine is configured for converting thermal energy to mechanical energy. The heat engine includes a first discrete element of a shape memory alloy having a crystallographic phase changeable between austenite and martensite in response to the temperature difference between the first region and the second region. The first discrete element of the shape memory alloy expands and contracts in response to the phase change to exert a linear force. A motion conversion mechanism is operatively connected to the first discrete element to be driven by the linear force and a component is driven by the motion conversion mechanism.
摘要:
An energy harvesting system comprises a first region and a second region having a temperature difference therebetween. A heat engine is configured for converting thermal energy to mechanical energy. The heat engine includes a first discrete element of a shape memory alloy having a crystallographic phase changeable between austenite and martensite in response to the temperature difference between the first region and the second region. The first discrete element of the shape memory alloy expands and contracts in response to the phase change to exert a linear force. A motion conversion mechanism is operatively connected to the first discrete element to be driven by the linear force and a component is driven by the motion conversion mechanism.
摘要:
A shape memory alloy (SMA) heat engine includes a first rotatable pulley, a second rotatable pulley, and an SMA material disposed about the first and second rotatable pulleys and between a hot region and a cold region. A method of starting and operating the SMA heat engine includes detecting a thermal energy gradient between the hot region and the cold region using a controller, decoupling an electrical generator from one of the first and second rotatable pulleys, monitoring a speed of the SMA material about the first and second rotatable pulleys, and re-engaging the driven component if the monitored speed of the SMA material exceeds a threshold. The SMA material may selectively change crystallographic phase between martensite and austenite and between the hot region and the cold region to convert the thermal gradient into mechanical energy.
摘要:
A tunable impedance load bearing structure includes a support comprising an active material configured for supporting a load, wherein the active material undergoes a change in a property upon exposure to an activating condition, wherein the change in the property is effective to change an impedance characteristic of the support.
摘要:
A mechanical system selectively imparts a prescribed motion to an output load using two or more actuators, including at least one having an active material element. The output load can be a locking member when the system is a vehicle transmission, a shuttle car of a linear system, or another device. A controller determines a total motive force required for imparting the prescribed motion, and selectively commands a combination of the actuators to provide the total motive force, apportioning the total motive force between the various actuators to optimize the performance of the system. An algorithm determines which combination of the actuators is the most suitable in moving the output load, and continuously modified this combination as needed as the output load is moved. The other actuator or actuators are then selectively energized as needed to provide the total motive force depending on this suitability determination.
摘要:
An energy harvesting system comprises a first region and a second region having a temperature difference therebetween. A plurality of heat engines are located proximate to the conduit and configured for converting thermal energy to mechanical energy. The heat engines each include a shape memory alloy forming at least one generally continuous loop. The shape memory alloy driven to rotate by heat exchange contact with each of the first region and the second region. At least one pulley for each of the plurality of heat engines is driven by the rotation of the respective shape memory alloy, and each of the at least one pulleys is operatively connected to a component to thereby drive the component.
摘要:
A cooling assembly adapted for use with an exothermic system, includes a manipulable cooling member and/or source, and an active material element operable to selectively inter-engage or further engage the member or source and the system through displacement or formation of a thermal link.
摘要:
A fore-aft positioning adjuster adapted for use with an object, such as a seat, includes a locking mechanism, and an actuator employing an active material element operable to undergo a reversible change when exposed to or occluded from an activation signal, and configured to selectively cause the mechanism to release, so that the object can be repositioned, as a result of the change.