US 4,544,988 AGranted

Bistable shape memory effect thermal transducers

AssigneeArmada Corporation

InventorPeter A. Hochstein

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Abstract

An electrothermal actuator assembly including a primary or armature member movable between first and second positions and biased to remain in either the first and second position to which it is moved with wires each made of shape memory material attached to the primary or armature member and acting in opposition to one another but, alternatively, when electrical current is passed through the respective wires to increase their temperature whereby they shorten in length to move the primary or armature. A switch supplies electrical current selectively through contacts interconnected by the primary or armature member, but only to one wire at a time for moving the armature from one position to another. The armature or primary member may move rectilinearly between first and second positions or may be rotatably supported for movement between first and second positions. The armature or primary member may also interconnect a set of load contacts to supply power to a load in one of the positions.

An electrothermal actuator assembly comprising:

support means (10);
primary means (12, 14, 15, or 16) supported by said support means (10) for movement between first and second positions;
a first temperature-sensitive element (20) made of material which exhibits shape memory due to thermoelastic, martensitic phase transformation extending between said support means (20) and said primary means (12, 14, 15, or 16);
said first element (20) being responsive to an increase in temperature above a predetermined transition temperature for reacting between said primary means (12, 14, 15, or 16) and said support means (10) to move said primary means (12, 14, 15, or 16) to said second position;
characterized by a second temperature-sensitive element (22) made of material which exhibits shape memory due to thermoelastic, martensitic phase transformation extending between said support means (10) and said primary means (12, 14, 15, or 16);
said second element (22) being responsive to an increase in temperature above said transition temperature for reacting between said primary means (12, 14, 15, or 16) and said support means (10) to move said primary means (12, 14, 15, or 16) to said first position;
and said primary means including biasing means (24, 26, 28, or 24', 26', 28', or 34) for maintaining said primary means (12, 14, 15, or 16) in said first position until said first element (20) is heated sufficiently to move said primary means (12, 14, 15, or 16) to said second position and for maintaining said primary means (12, 14, 15, or 16) in said second position until said second element (22) is heated sufficiently to move said primary means (12, 14, 15, or 16) to said first position, and circuit means for supplying electrical current through said first element (20) a limited time period sufficient to provide said increase in temperature thereof while preventing current flow through said second element (22) to move said primary means (12, 14, 15, or 16) to said second position and for supplying electrical current through said second element (22) a limited time period sufficient to provide said increase in temperature thereof while preventing current flow through said first element (20) to move said primary means to said first position.

4 more elements

Abstract

Claims10