Patent ID: 9714644
Date: 2017-07-25
CPC Classifications: F03G,F04D,F16J

Claim:
1. An actuator comprising: a cylinder having an axial dimension; a piston axially movable within the cylinder with the cylinder having a closed upper end and lower end which is sealed around the piston, the piston having one end connectable to an operator; a cavity occupying a space within the cylinder between the upper and lower ends and which space at least partially surrounds a portion of the piston, an axial dimension of the piston extending through the space within the cavity when the piston is in a first position of its travel, the axial dimension of the piston having at least two separate diameters with a largest of the diameters leading a smaller of the diameters in a direction of travel of the piston to move the piston to a second position, the two diameters occupying at least one portion of the space when the piston is in the first position; a material inside the cavity at least partially surrounding a transition between the at least two separate diameters, the material expanding upon an increase in temperature to exert a force on the piston, wherein the force is exerted over an area around an outer circumference of the piston over the transition between the at least two separate diameters of the piston, that causes the piston to move to the second position when the material rises above a preselected temperature; wherein the piston extends axially through the material within the cavity; and a thermally activated safety lock configured, separately from the material, to prevent the piston from moving from the first position to the second position when the material is below the preselected temperature and passively unlock and allow the piston to move in the direction toward the second position when the material rises above the preselected temperature.