Valve

Abstract

A valve device particularly adapted for remote electrical operation at very low power levels has actuator means which are located outside a valve body but which are operatively connected to a valve member within the body through a flexible diaphragm which seals the valve body without excessively restricting movement of the valve member within the valve body. The actuator means are selectively operable for moving the valve member to open and close the valve. Preferably, at least the flexible diaphragm is exposed to fluid pressures within the valve body so that the valve member is normally moved to closed valve position with selected force in response to these pressures when fluid is introduced into the valve body. The actuator means preferably comprises a wire of a selected nickel-titanium alloy which is secured outside the valve body between the body and the valve operating member, the wire being of selected small diameter to be deformed from an original length to a greater length as the valve member is moved to closed valve position with said force while the wire alloy displays a relatively low modulus of elasticity below a transition temperature. However, the wire abruptly returns to its original length and displays a relatively higher modulus of elasticity to move the valve member to open valve position against this force when the wire alloy is heated above its transition temperature. The disclosed valve device includes means directing electrical current through the small actuator wire at low power levels for selectively heating the wire to operate the valve device.