Shape memory alloy actuator

A shape memory alloy actuator comprising:

• a body displaceable between a first and a second position,
• at least one first wire made of a shape memory alloy such as nitinol, said first wire being at one end connected to said body such that shortening of the length of said first wire exerts a force on said body for moving said body from said second to said first position,
• a biasing means selected from the group consisting of at least one of a tension spring, a compression spring, a flat spring and a piston and cylinder mechanism, and
• a rotatably arranged intermediate member connected to said body and to said biasing means,
• said biasing means being adapted for exerting a rotation force on said intermediate member for rotating said intermediate member around an axis of rotation in a first direction of rotation from a first angular position to a second angular position, said intermediate member being connected to said body such that rotation of said intermediate member in said first direction of rotation displaces said body from said first position to said second position, and
• said biasing means and said intermediate member being arranged and adapted such that the lever or moment arm of said rotation force with respect to said axis of rotation is larger when said intermediate member is in said second angular position than when said intermediate member is in said first angular position such that said lever or moment arm of said rotation force increases when said intermediate member rotates in said first direction of rotation.

A shape memory alloy actuator comprising:

• a body displaceable between a first and a second position,
• at least one first wire made of a shape memory alloy such as nitinol, said first wire being at one end connected to said body such that shortening of the length of said first wire exerts a force on said body for moving said body from said second to said first position,
• a biasing means selected from the group consisting of at least one of a tension spring, a compression spring, a flat spring and a piston and cylinder mechanism, and
• a rotatably arranged intermediate member connected to said body at a force transmission point on said body and connected to or integral with said biasing means,
• said biasing means being adapted for exerting a rotation force on said intermediate member for rotating said intermediate member around an axis of rotation in a first direction of rotation from a first angular position to a second angular position, said intermediate member being connected to said body such that rotation of said intermediate member in said first direction of rotation displaces said body from said first position to said second position, and
• said intermediate member and said body being arranged and adapted such that said rotation force is transmitted to said body as a displacement force applied at said force transmission point for moving said body from said first to said second position, and such that the lever or moment arm of said displacement force with respect to said axis of rotation is larger when said intermediate member is in said first angular position than when said intermediate member is in said second angular position such that said lever or moment arm of said displacement force with respect to said axis of rotation decreases when said intermediate member rotates in said first direction of rotation.

A shape memory alloy motor comprising:

• a shape memory alloy actuator, having
• a body displaceable between a first and a second position,
• at least one first wire made of a shape memory alloy such as nitinol, said first wire being at one end connected to said body such that shortening of the length of said first wire exerts a first displacement force on said body for moving said body from said second to said first position,
• a biasing means selected from the group consisting of at least one of a tension spring, a compression spring, a flat spring and a piston and cylinder mechanism arranged and adapted for exerting a second displacement force on said body for moving said body from said first to said second position,
• a gear having a first and second rotation direction,
• said body having a portion adapted to fit between two adjacent teeth of said gear, and said body and said gear being adapted and arranged such that in said first position said portion is located between a pair of teeth of said gear and in said second position said portion is located between the adjacent pair of teeth of said gear reckoned in said second rotation direction of said gear such that said second displacement force will cause said body to rotate said gear in said first direction.

A shape memory alloy motor comprising:

• a shape memory alloy actuator, having
• a body displaceable between a first and a second position,
• at least one first wire made of a shape memory alloy such as nitinol, said first wire being at one end connected to said body such that shortening of the length of said first wire exerts a first displacement force on said body for moving said body from said second to said first position,
• a biasing means selected from the group consisting of at least one of a tension spring, a compression spring, a flat spring and a piston and cylinder mechanism arranged and adapted for exerting a second displacement force on said body for moving said body from said first to said second position,
• a rack having a first and second displacement direction,
• said body having a portion adapted to fit between two adjacent teeth of said rack, and said body and said rack being adapted and arranged such that in said first position said portion is located between a pair of teeth of said rack and in said second position said portion is located between the adjacent pair of teeth of said gear reckoned in said second displacement direction of said rack such that said second displacement force will cause said body to displace said rack in said first direction.