Switchless electrothermal actuator with constant electrical current input

Claim 1

A SWITCHLESS ELECTROTHERMAL ACTUATOR FOR IMPARTING MOTION TO MECHANISM, COMPRISING (A) A HIGH PRESSURE CASING CONTAINING EXPANSIBLE AND CONTRACTIBLE MATERIAL AND A RECIPROCAL SHAFT HAVING A PISTON PORTION IN THE CASING AND A WORK-CONTACTING PORTION EXTENDING BEYOND THE CASING, (B) AN ELECTRICAL HEATING ELEMENT IN THE CASING AND A CONSTANT ELECTRICAL CURRENT INPUT CONNECTED TO SAID ELEMENT FOR HEATING THE EXPANSIBLE MATERIAL AND ACTUATING THE SHAFT, (C) A VALVE HOUSING SURROUNDING AND ENCLOSING THE HIGH PRESSURE CASING IN SPACED RELATIONSHIP THERETO FOR CIRCULATION OF A COOLING MEDIUM BETWEEN THE CASING AND HOUSING FOR COOLING THE CASING AND ITS CONTENTS, (D) A FLUID INLET AND A FLUID OUTLET IN THE HOUSING, AND (E) A COOLING MEDIUM IN THE HOUSING HAVING TEMPERATURE LOWER THAN THE TEMPERATURE OF THE HIGH PRESSURE CASING WHEN HEATED BY THE HEATING ELEMENT, SAID COOLING MEDIUM CIRCULATING THROUGH THE SPACE BETWEEN THE CASING AND HOUSING IN HEAT EXTRACTING RELATIONSHIP TO THE EXTERIOR OF THE CASING WALLS FOR CONTROLLING THE TEMPERATURE OF THE CASING AND EXCONTROLLING THE TEMPERATURE OF THE CASING AND EXPANSIBLE MATERIAL WITHOUT MEANS FOR VARYING OR INTERRUPTING THE CONSTANT FLOW OF ELECTRICAL CURRENT THERETO.