Patent ID: 6427720
Filing Date: 2002-08-06
Classification: F15B,Y10T

Abstract:
A pilot operated 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 the valve hole; a piston chamber formed on at least one end side of said valve member; a piston slidably received in said piston chamber, said piston operating by the action of pilot fluid pressure to change over said valve member; a pilot valve for supplying said piston with a pilot fluid; a through hole formed on said casing so that an object to be detected on said piston can be seen therethrough; an optical sensor disposed so as to be able to project and receive light relative to said piston through said through hole, said optical sensor detecting operating positions of said piston by the light reflected from said piston; breathing chambers each opened to the outside, said breathing chambers being each disposed between said valve member and said piston, wherein said object to be detected which protrudes parallel with the axis of said piston is disposed on the end face of said piston, adjacent to said breathing chamber; and a recess in which said object to be detected is fit, said recess being disposed in the wall surface of said breathing chamber, in said casing, wherein said through hole is formed at a position facing said recess, whereby operating positions of said object to be detected can be detected in said recess.