US 12,228,113 B2
SMA actuator assembly
James Howarth, Cambridge (GB); Andrew Benjamin Simpson Brown, Cambridge (GB); René Kist, Cambridge (GB); Stephen Matthew Bunting, Cambridge (GB); and Alexander Doust, Cambridge (GB)
Assigned to CAMBRIDGE MECHATRONICS LIMITED, Cambridge (GB)
Appl. No. 18/569,309
Filed by CAMBRIDGE MECHATRONICS LIMITED, Cambridge (GB)
PCT Filed Jun. 17, 2022, PCT No. PCT/GB2022/051551
§ 371(c)(1), (2) Date Dec. 12, 2023,
PCT Pub. No. WO2022/263856, PCT Pub. Date Dec. 22, 2022.
Claims priority of application No. 2108682 (GB), filed on Jun. 17, 2021.
Prior Publication US 2024/0271606 A1, Aug. 15, 2024
Int. Cl. F03G 7/06 (2006.01)
CPC F03G 7/06143 (2021.08) [F03G 7/0645 (2021.08)] 11 Claims
OG exemplary drawing
 
1. A shape memory alloy (SMA) actuator assembly for driving or rotating a movable part in a predetermined direction or sense by a plurality of repeated incremental steps, the SMA actuator assembly comprising:
the movable part;
a first engagement portion for engaging the movable part;
a second engagement portion for engaging the movable part;
two SMA wires arranged to move the first engagement portion such that the first engagement portion repeatedly, for each of said incremental steps, is configured to:
engage with the movable part from a starting position;
exert a force or torque on the movable part in the predetermined direction; and
disengage from the movable part and return to the starting position,
wherein:
the exertion of the force or torque on the movable part and the engaging and disengaging with the movable part are caused by contraction or relaxation of the two SMA wires,
the two SMA wires together are arranged to control the engagement and/or disengagement of the first engagement portion,
a first SMA wire of the two SMA wires is arranged, on contraction, to cause the first engagement portion to exert a force or torque on the movable part in the predetermined direction or sense,
a second of the two SMA wires is arranged, on contraction, to cause the first engagement portion to exert a force or torque on the movable part in a second direction or sense that is opposite to the predetermined direction or sense, and
at least one SMA wire is arranged to move the second engagement portion to engage with the movable part to control the position of the movable part during at least a part of the time when the first engagement portion is disengaged from the movable part.