Shape memory alloy actuated fluid control valve

摘要

A fluid control valve having a shaped memory alloy (SMA) driven actuator is disclosed. The SMA driven actuator includes a first frame section coupled to a valve body and fixed in relation thereto, a second frame section coupled to a movable element of the valve body and movable in relation to the valve body, and a mulitiplicity of SMA wire sections coupling the first and second frame sections for moving the movable element from a biased first position to a second position when heated. An electrical controller controls the heating of the SMA wire sections by regulating current therethrough, preferably using pulse width modulation techniques. The electrical controller may be governed by a position measurement signal proportional to the position of the movable element to regulate current to the SMA drive element to position the movable element to a desired position. The position measuring signal may be provided from a position measuring element integral to the valve actuator. The valve actuator may also include a temperature controller governed by an electrical temperature signal provided by a temperature-sensing means in proximity to the SMA drive element to activate a cooling device for reducing the temperature surrounding the SMA drive element when activated. A digital selector switch may be used for generating a digital code of a selected heating rate which may govern the electrical controller to regulate current to the SMA drive element. The electrical controller may also be governed by both a position measurement and a temperature signal to regulate current to the SMA drive element and to control the cooling device to position the movable element to a desired position. The actuator may include at least one bobbin that is wound with a multiplicity of wire windings. A conductive material may be applied to the surface of grooved sections of the bobbin onto which the SMA wire windings are wound. Alternatively, the SMA wire may be coated with a conductive material and then wound about the bobbin and thereafter, the conductive material may be removed from the surface of the SMA wire not in contact with the bobbin.