US 4,524,343 A · Self-regulated actuator

Abstract

A self-regulated actuator is disclosed having a shape-memory element which is heated preferably by passing electrical current therethrough and having a reset mechanism including a circuit-breaking mechanism. The shape-memory element provides the force to retract the actuator when heated. The reset mechanism utilizes a spring-biased latch plunger that resets the actuator as soon as it has retracted a specific distance. The reset mechanism also acts as a circuit-breaking mechanism to electrically interrupt current heating the shape-memory element. The reset mechanism provides near-instant reset time and overcomes the longer wait period otherwise associated with the natural cooling of the shape-memory element. The reset mechanism prevents overheating of the shape-memory element and precludes the necessity for additional hardware to interrupt the circuit after actuation is completed. Also discussed is a self-protection means that protects the shape-memory element from deliberate and accidental overloads and to accommodate the extra motion required for high-cycle design life.

Claims12

Dependent claims

A self-regulated actuator comprising:

a shape-memory element capable of being longitudinally expanded when in its martensitic state and capable of being longitudinally recovered when in its austenitic state, said element capable of dimensional recovery when heated from said martensitic state to said austenitic state, said element having a first end and a second end along the longitudinal axis thereof;
a plunger located at the first end of said element;
a latch means connecting said plunger to said first end of said element when said element is longitudinally expanded, said latch means releasing said plunger at a predetermined position as said element recovers;
spring means connected to said plunger biasing said plunger away from said element, said spring means capable of moving said plunger away from said element when the plunger is released by the latch means;
and
element return means biasing said first and second ends away from each other and capable of expanding said element when said element is in its martensitic state.

3 more elements

Dependencies are inferred from the claim text.

Self-regulated actuator

Life of this patent

Self-regulated actuator

Life of this patent

Abstract

Claims12