Electrical actuator having smart muscle wire
An electrical actuator is characterized by applying electrical current directly to a smart wire to produce an output motion. The smart wire is looped around a drive member that is engaged with a moveable member, fixed at both ends to electrical terminals, and contains one or more coils between the electrical terminals and the drive member. Smart wire coils can either be wrapped around a reel in a helical fashion or moveably disposed in flexible tubing for support. Direct electrical current applied to the smart wire results in heating and contraction of the wire. Subsequent removal of electrical current allows the wire to cool and return to its original size and shape. The force and stroke of the electrical actuator can be tailored to meet specific requirements by changing wire diameter and length.
1 . An electrical actuator comprising:
a drive member;
a moveable member engaged with said drive member;
at least one smart wire made of a shape memory alloy having two ends, wherein said smart wire is looped around said drive member; and
a electrical terminal connected to each of two said smart wire ends, wherein said terminals are adjacent to each other and spaced from said drive member;
wherein said smart wire has at least one coil located between said electrical terminals and said drive member.
2 . The electrical actuator of claim 1 wherein said smart wire is comprised of a nickel-titanium alloy, said smart muscle wire contracts when heated by direct application of electrical current and returns to its original shape upon cooling.
3 . The electrical actuator of claim 1 wherein the moveable member is a slide.
4 . The electrical actuator of claim 1 containing at least two said smart wires in parallel.
5 . The electrical actuator of claim 1 containing a plurality of coils facilitating increased movement of said reaction member and said moveable member.
6 . The electrical actuator of claim 5 containing flexible tubing supporting said smart wires, wherein said flexible tubing prevents entanglement of said smart wires in said plurality of coils and wherein said smart wires are moveably disposed in said flexible tubing.
7 . The electrical actuator of claim 5 wherein said plurality of coils are wrapped around a reel, said plurality of coils wrapped in helical grooves in said reel to separate said plurality of coils.