Lock device with shape memory actuating means
A lock device which includes a bolt actuated by a flexible shape memory element. The memory element can assume an extended or a shortened configuration as a result of heating. A constraining element which includes two points between which an intermediate portion of the shape memory extends is also provided. The two points belong to a moveable transmission element which moves when the shape memory element extends. As a result, a controlled element is moved from between an operating position and a non-operating position.
1. A lock device comprising:
a body;
a controlled element which is mounted on the body for linear sliding between an operating and a non-operating position in a first direction;
a flexible shape memory element which is actuated to displace the controlled element from the operating position to the non-operating position by extending or shortening a length thereof;
means for heating the shape memory element, so as to cause passage thereof from an extended configuration to a shortened configuration due to shrinkage of the shape memory element and thus displace the controlled element from the operating position to the non-operating position, the shape memory element having a first end anchored with respect to the body, a second end connected to the controlled element and a third end anchored with respect to the body, the first end and the third end of the shape memory element being connected to the means for heating;
a first transmission element and a second transmission element both coupled to the body for linear sliding in said first direction, the first transmission element provided so as to contact the shape memory element at a point between the first end and the second end thereof and the second transmission element provided so as to contact the shape memory element at a point between the second end and the third end thereof; and
a connection element for mechanically connecting the first and second transmission elements to the controlled element,
wherein the first and second transmission elements are movable so as to shift with respect to the body in said first direction, during passage of the shape memory element from the extended configuration to the shortened configuration,
wherein a portion of the shape memory element that extends between said first end and the first transmission element forms a first portion, a portion of the shape memory element that extends between the first transmission element and the controlled element forms a second portion, a portion of the shape memory element that extends between the controlled element and the second transmission element forms a third portion and a portion of the shape memory element that extends between the second transmission element and said third end forms a fourth portion,
wherein during passage from the extended configuration to the shortened configuration, the shape memory element generates a traction on the first and second transmission elements to cause the shift thereof in the first direction which in turn causes displacement of the controlled element via the connection element.
2. The device according to claim 1 , wherein shrinkage of the first portion and the fourth portion of the shape memory element causes the displacement of the controlled element and shrinkage of the second portion and the third portion of the shape memory element causes additional displacement of the controlled element.
3. The device according to claim 2 , wherein a movement distance of the controlled element is twice a movement distance of first and second transmission elements.
4. The device according to claim 1 , wherein elastic means are provided for constantly biasing the controlled element towards the operating position thereof.
5. The device according to claim 1 , wherein the means for heating the shape memory element comprise means for electric supply, including at least a switch having a switching element that is actuated by the controlled element when the controlled element is displaced from the operating position to the non-operating position.
6. The device according to claim 1 , wherein the shape memory element is provided with a coating made of synthetic material, said coating being elastically deformed when the shape memory element passes from the extended configuration to the shortened configuration.
7. The device according to claim 1 , wherein the first and second transmission elements are mounted for sliding linearly in respective guide means that are defined in the body.
8. The device according to claim 1 , wherein each of the first and second transmission elements comprise a first pin and the connection element fixedly retains the first pins, and
wherein the connection element includes a slot for receiving a second pin of the controlled element.
9. The device according to claim 8 , wherein movement of the connection element causes movement of the second pin of the controlled element due to shrinkage of the first and fourth portions of the shape memory element and thereafter shrinkage of the second and third portions of the shape memory element causes movement of the second pin of the controlled element within the slot of the connection element.