Bistable SME actuator with retainer

A bistable shape memory effect, SME, mechanism comprising:

• a housing;
• an actuator in said housing for actuation along a travel stroke between first and second positions;
• a first SME element in said housing and coupled to said actuator and moving said actuator to said first position upon heating of said first SME element above its transition temperature;
• a second SME element in said housing and coupled to said actuator and moving said actuator to said second position upon heating of said second SME element above its transition temperature;
• retaining means mechanically frictionally holding said actuator at each end of its travel stroke until actuated to its other position by heating of the respective SME element.

A bistable shape memory effect, SME, mechanism comprising:

• a housing;
• an actuator in said housing for actuation along a travel stroke between first and second positions;
• a first SME element in said housing and coupled to said actuator and moving said actuator to said first position upon heating of said first SME element above its transition temperature;
• a second SME element in said housing and coupled to said actuator and moving said actuator to said second position upon heating of said second SME element above its transition temperature;
• a resiliently biased friction member applying a force against said actuator generally perpendicularly to the direction of said travel stroke, and a lost motion coupling between said actuator and said SME elements providing lost motion along the direction of said travel stroke,
• such that after heating of said first SME element and movement of said actuator along its travel stroke to said first position, said first SME element is allowed to repose upon cooling, without moving said actuator from said first position, said lost motion permitting return repose movement of said first SME element by an amount equal to said lost motion without causing return movement of said actuator, said actuator being held at said first position by said perpendicular bias force of said resilient friction member,
• and such that after heating of said second SME element and movement of said actuator along its travel stroke to said second position, said second SME element is allowed to repose upon cooling, without moving said actuator from said second position, said lost motion permitting return repose movement of said second SME element by an amount equal to said lost motion without causing return movement of said actuator, said actuator being held at said second position by said perpendicular bias force of said resilient friction member.