Torque actuator incorporating shape memory alloy composites

A rotary actuator comprising:

• (a) a rotating member configured to be selectively rotated;
• (b) a magnetically actuatable member configured to rotate the rotating member when actuated, the magnetically actuatable member comprising a shape memory alloy;
• and
• (c) a hybrid magnetic trigger configured to selectively actuate the magnetically actuatable member, the hybrid magnetic trigger comprising a permanent magnet portion, an electromagnet portion, and a yoke configured to couple a magnetic flux from the hybrid magnetic trigger to the shape memory alloy.

A method for rotating a mass, comprising the steps of:

• (a) coupling a magnetically actuatable member to the mass, the magnetically actuatable member comprising at least one of:
• (i) a ferromagnetic shape memory alloy exhibiting both ferromagnetic and shape memory properties;
• and
• (ii) a ferromagnetic mass coupled to a shape memory alloy;
• and
• (b) using a magnetic force to displace the magnetically actuatable member by energizing a magnetic trigger, displacement of the magnetically actuatable member causing a corresponding rotation of the mass,
• wherein energizing the magnetic trigger includes the step of employing a yoke to couple a magnetic flux from the magnetic trigger to the shape memory alloy.

A method for fabricating a spring comprising a ferromagnetic shape memory alloy (FSMA) composite, the spring having a generally quadrilateral cross-sectional shape, the method comprising the steps of:

• (a) providing a ferromagnetic material having a generally quadrilateral cross-sectional shape;
• (b) forming a plurality of peripheral depressions into an outer surface of the ferromagnetic material, such that the ferromagnetic material obtains a generally stretched X shaped cross-sectional shape;
• and
• (c) filling the plurality of depressions with a shape memory alloy (SMA), so that the resulting FSMA composite spring attains the generally quadrilateral cross sectional shape, the SMA material in the depressions being distributed peripherally about the generally quadrilateral cross sectional shape.

A method for selectively controlling a stroke of a linear actuator, comprising the steps of:

• (a) providing a plurality of individual ferromagnetic shape memory alloy (FSMA) spring actuators, each FSMA spring actuator comprising a FSMA spring and a hybrid magnetic trigger configured to selectively actuate the FMSA spring, the hybrid magnetic trigger comprising a permanent magnet portion, an electromagnet portion, and a yoke configured to couple a magnetic flux from the hybrid magnetic trigger to individual FSMA spring actuators;
• (b) assembling the plurality of FSMA spring actuators into a stack to achieve a desired linear stroke;
• and
• (c) selectively actuating at least one of the plurality of FSMA spring actuators, wherein increasing the number of FSMA spring actuators that are actuated will result in a larger linear stroke.

A hybrid magnetic trigger configured to enable a shape memory alloy member to be selectively actuated, the hybrid magnetic trigger comprising:

• (a) at least one permanent magnet;
• (b) at least one electromagnet;
• and
• (c) a yoke configured to couple a magnetic flux from the hybrid magnetic trigger to the shape memory alloy, such that when the hybrid magnetic trigger is energized, the shape memory alloy is attracted to the yoke and is thereby actuated, the yoke comprising a plurality of fences configured to direct magnetic flux from the hybrid magnetic trigger into the shape memory alloy.