Patent ID: 6702250
Filing Date: 2004-03-09
Classification: F01L,F16K

Abstract:
A magnetostrictive valve actuator comprising:a body having a first cavity and a second cavity, the first cavity having a distal end and a proximal end extending along a longitudinal axis and the second cavity forming a hydraulic chamber in communication with the first cavity via a first bore having a first sealing diameter; a first piston positioned in the first bore, the first piston being displaceable in the direction of the longitudinal axis; a second bore having a second sealing diameter, the second bore being in communication with the hydraulic chamber; a second piston positioned in the second bore, the second piston being displaceable with in the second bore in response to changes in hydraulic pressure within the hydraulic chamber; a magnetostrictive member having a predetermined length disposed substantially in the direction of the longitudinal axis of the first cavity, the magnetostrictive member being in operative contact with the first piston; an adjustable member coupled to the housing, the adjustable member engaging one end of the magnetostrictive member distal to the first piston; a coil that generates a magnetic field disposed proximate the magnetostrictive member such that magnetic flux passes through the magnetostrictive member upon excitation of the coil, causing the predetermined length to increase, forcing the first piston to be displace toward the hydraulic chamber and the second piston to move under the influence of the hydraulic pressure created by the displacement of the first piston; and biasing means disposed in a third bore and operatively arranged to exert a predetermined prestress force on the magnetostrictive member.