Electromagnetic pilot type valve

Claim 1

A generally compact multi-piston type electromagnetic pilot valve comprising a single valve housing, a pilot port, a main valve port, at least one auxiliary pilot port provided between said pilot port and said main valve port having diameters progressively smaller than that of said main valve port and gradually increased at a predetermined rate with respect to that of said pilot port, cup-shaped piston valves for opening and closing said main valve port and said at least one auxiliary pilot port, said piston valves including front, rear and inner lower surfaces, first passages for communicating and acting on the front and the inner lower surfaces of said piston valves, second passages being defined by the outer circumference of said piston valves, said second passages communicating and acting on said front, said rear and said inner lower surfaces of said piston valves, and a plunger being provided to open and close said pilot port, a first auxiliary pilot port adjacent to said pilot port being opened and closed by at least one of said auxiliary piston valves while opening and closing said pilot port with said plunger, and said piston valves, said pilot port, said auxiliary pilot port, said main valve port and said plunger are disposed in parallel relationship with each other within said valve housing; whereby a main valve body of a generally large diameter may be operated with a generally small electromagnetic pilot valve.