Abstract: An energy harvesting system comprises a first region having a first temperature and a second region having a second temperature. A heat engine is configured for converting thermal energy to mechanical energy. The heat engine includes a plurality of discrete elements of a shape memory alloy each having a crystallographic phase changeable between austenite and martensite in response to a temperature difference between the first region and the second region. At least one member of the heat engine is driven to rotate about a first axis by the phase change of the plurality of discrete elements.

Abstract: An inlet, positioned to access the flow of air passing around and under a moving vehicle, may draw in air which is conveyed through a duct and discharged to cool a brake on a vehicle. The inlet has a closure. The closure is opened and closed on demand by a temperature-operated actuator incorporating an active or smart material under the direction of a controller. In embodiments, a sensor, suitably positioned to sense a temperature representative of the brake temperature, communicates the sensed brake temperature to the controller. The controller may respond to the sensed brake temperature, by triggering operation of the actuator. Typically the closure is opened to allow passage of cooling air to the brake when the sensed brake temperature exceeds, or is anticipated to exceed, a predetermined temperature.

Abstract: A vent assembly is disposed within an interior space of a vehicle for opening and closing fluid communication between the interior space and an exterior of the vehicle. The vent assembly includes a housing defining a plurality of openings and a plurality of vanes disposed in the openings. An actuator mechanism moves the vanes between an open position and a closed position, and includes a shaped memory alloy (SMA) member for actuating the vanes between the open and closed positions. The SMA member is activated when a hatch of the vehicle is open to move the vanes into the open position and thereby open fluid communication between the interior space and the exterior to alleviate excessive air pressure buildup during closure of the hatch.

Abstract: A method of controlling and/or predicting the remaining useful life of an active material actuator, such as a shape memory alloy wire, includes obtaining historical actuation data of an inherent system variable, such as electrical resistance, over a secondary variable, such as time, determining a normal operating envelope having upper and lower bounds based on the data, determining a current profile for a given actuation cycle, and comparing the shape of the current profile to the envelope to determine an out-of-bounds event.

Abstract: 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.

Abstract: An energy harvesting system includes a heat engine and a component configured to be driven by operation of the heat engine. The heat engine includes a first member, a second member, a shape memory alloy material, and a tensioner. The second member is spaced from the first member. The shape memory alloy material operatively interconnects the first member and the second member. The shape memory alloy material is configured to selectively change crystallographic phase from martensite to austenite and thereby contract in response to exposure to a first temperature. The shape memory alloy material is also configured to selectively change crystallographic phase from austenite to martensite and thereby expand in response to exposure to a second temperature. The tensioner is configured to apply tension to the shape memory alloy material as the shape memory alloy material selectively expands and contracts such that the shape memory alloy material is taut.

Abstract: A pumping assembly is provided. The assembly includes a first movable element selectively movable within a first pump housing and an actuator including an active material. The active material is configured to undergo a change in attribute in response to an activation signal. The active material is operatively connected to the first movable element such that the change in attribute causes the first movable element to move within the first pump housing. In one example, the active material is a shape memory alloy material having a crystallographic phase that is changeable between Austenite and Martensite in response to the activation signal.

Abstract: An exhaust system configured for converting thermal energy to mechanical energy includes a source of thermal energy provided by a temperature difference between an exhaust gas having a first temperature and a heat sink having a second temperature that is lower than the first temperature. The exhaust system also includes a conduit configured for conveying the exhaust gas, a heat engine disposed in thermal relationship with the conduit and configured for converting thermal energy to mechanical energy, and a member disposed in contact with the conduit and configured for conducting thermal energy from the conduit to the heat engine. The heat engine includes a first element formed from a first shape memory alloy having a crystallographic phase changeable between austenite and martensite at a first transformation temperature in response to the temperature difference between the exhaust gas and the heat sink.

Abstract: A system for and method of providing overload protection for an active material actuator, includes a magnetically functioning mechanism comprising, for example, one or more permanent or electromagnets, and/or magnetorheological fluid, and configured to produce a holding force less than the capacity of the actuator, and more preferably, a modifiable holding force responsive to load influencing conditions.

Abstract: A cooling system configured for converting thermal energy to mechanical energy includes a source of thermal energy provided by a temperature difference between a heat source having a first temperature and a coolant having a second temperature that is lower than the first temperature. The cooling system includes a cooling circuit configured for conveying the coolant to and from the heat source. The cooling circuit includes a conduit and a pump in fluid communication with the conduit and configured for delivering the coolant to the heat source. The cooling system also includes a heat engine disposed in thermal relationship with the conduit and configured for converting thermal to mechanical energy. The heat engine includes a first element formed from a first shape memory alloy having a crystallographic phase changeable between austenite and martensite at a first transformation temperature in response to the temperature difference between the heat source and coolant.

Abstract: A system for and method of reducing the effects of preheat period variation in shape memory alloy actuation, include sensing the removal of motion delay due to slack, backlash, and/or compliance in the actuator and drive-train of the system, and determining actuator activation, as a result thereof.

Abstract: An energy harvesting system includes a heat engine and a component. The heat engine includes a belt, a first member, and a second member. The belt includes a strip of material and at least one wire at least partially embedded longitudinally in the strip of material. The wire includes a shape memory alloy material. A localized region of the at least one wire is configured to change crystallographic phase between martensite and austenite and either contract or expand longitudinally in response to exposure to a first temperature or a second temperature such that the strip of material corresponding to the localized region also contracts or expands. The first member is operatively connected to the belt and moves with the belt in response to the expansion or contraction of the belt. The component is operatively connected to the first member such that movement of the first member drives the component.

Abstract: A method for executing mechanical overload protection to prevent commanding a control signal to a linear actuator that may mechanically overload the linear actuator when an overload condition of the linear actuator is detected, the linear actuator utilized for controlling a movable element associated with the linear actuator responsive to the control signal, includes monitoring an overload condition based on position change of the movable element associated with the linear actuator during an integration period and excess energy during the integration period, de-energizing the linear actuator when an overload condition has been detected, monitoring an overload retry counter based on the number of cycles the overload condition is detected, comparing the overload retry counter to an overload retry threshold, an reenergizing the linear actuator when the overload retry counter is less than the overload retry threshold and maintaining de-energizing of the linear actuator when the overload retry counter is at least

Abstract: A device and method for controlling a phase transformation temperature of a shape memory alloy is provided. The device includes a primary wire composed of the shape memory alloy. The primary wire defines first and second ends, the first end being attached to a fixed structure and the second end being able to displace. An activation source is thermally coupled to the wire and is operable to selectively cause the primary wire to reversibly transform from a Martensitic phase to an Austenitic phase during a cycle. A loading element is operatively connected to the primary wire and configured to selectively increase a tensile load on the primary wire when an ambient temperature is at or above a threshold temperature, thereby increasing the phase transformation temperature of the primary wire.

Abstract: A pressure relief valve includes a housing and vane that is movable to one of an open position and a closed position. A linear actuator mechanically couples between the movable vane and the housing. The linear actuator is a wire device fabricated from a shape memory alloy. An actuable latching system is configured to retain the movable vane in one of the open position and the closed position for an indeterminate time period.

Abstract: A method of starting a heat engine includes exposing an element of the heat engine to a source of thermal energy provided by a temperature difference between a heat source having a first temperature and a heat sink having a second temperature that is lower than the first temperature. The element is formed from a first shape memory alloy having a crystallographic phase changeable between austenite and martensite at a first transformation temperature in response to the temperature difference between the heat source and the heat sink. The method further includes changing the crystallographic phase of the first shape memory alloy to thereby convert thermal energy to mechanical energy, and inducing initial movement of the element in a desired operational direction to thereby start the heat engine.

Abstract: 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.

Abstract: A device is provided that may be adapted to control or monitor the pressure level of a fluid system. The device includes a member composed of a shape memory alloy in a superelastic state. The member is configured to undergo a phase change from a high modulus Austenitic phase to a low modulus Martensitic phase and stretch in response to an activation stress. In one embodiment, the member defines two ends such that one end of the member is operatively connected to a fixed point. Another end of the member is operatively connected to a movable element. As the member stretches in response to the activation stress, the movable element is translated relative to the fixed point. In another embodiment, the member includes two plates with respective holes that are selectively aligned when the first and second plates stretch or deform in response to the activation stress.

Abstract: An inlet, positioned to access the flow of air passing around and under a moving vehicle, draws in air which is conveyed through a duct and discharged to cool a brake on a vehicle. The inlet has a closure so that access of cooling air may be denied when the brake temperature is less than a predetermined temperature and opened only when the brake temperature exceeds that predetermined temperature. The closure is operated by a temperature-operated actuator. In embodiments the actuator may be suitably positioned to sense a temperature representative of the brake temperature and to incorporate a thermally activated phase change, active or smart material preselected to operate the inlet closure when the sensed brake temperature exceeds the predetermined temperature.

Abstract: Shape memory alloy (SMA) actuating elements are commonly simpler and of lower mass than alternative actuator designs and may find particular application in the transportation industry. Such SMA-powered devices are usually reliable and long-lived but the phase transformations which occur in the SMA alloy and are responsible for its utility are not totally reversible. This irreversibility, a consequence of irrecoverable strain, may progressively degrade the long-term actuator performance as the irrecoverable strain accumulates over many operating cycles. Methods and devices for compensating for these effects and extending the useful cycle life of SMA actuators are described.