Patent ID: 6263915
Filing Date: 2001-07-24
Classification: F15B,Y10T

Abstract:
A directional control valve having a position detecting function, comprising:a plurality of ports:a valve hole to which each of said ports is opened;a casing having said ports and said valve hole;a valve member for changing over flow passages, said valve member being slidably received in said valve hole;driving means for driving said valve member;a detection coil for generating an alternating magnetic field, said detection coil being disposed at a portion formed by non-magnetic material, in said casing;a detection head for changing an impedance of said detection coil by approaching or moving away from said detection coil, said detection head being disposed in said casing so as to be displaced in synchronization with said valve member;a signal processing circuit for applying an alternating voltage to said detection coil and detecting an operating position of said valve member from a change in the impedance of said detection coil; andsaid directional control valve being a double-pilot type directional control valve having two pistons and two pilot valves, wherein said two pilot valves are concentratedly installed in said casing at an end portion of a first piston of said two pistons, wherein said detection coil is installed at a position adjacent to a second piston of said casing, and wherein said detection head is disposed on a second piston of said two pistons.