Pressure control valve

Abstract

A pressure control valve includes a spool valve slidable in a valve sleeve having a supply port, an output port and an exhaust port, and adapted to receive a load caused by an electromagnet and applies through a push rod, a spring load, and an output pressure feedback load. The balance among the loads is arranged to control the output pressure at a level corresponding to the electric signal input to the electromagnet. Provision is made for preselecting the gradient of the attractive force of the electromagnet with respect to the stroke of a plunger slidable within the core of the electromagnet and for adjusting the axial position of the plunger. Specifically, the electromagnet includes a coil assembly, a cylindrical core having an axially extending opening through which receives the push rod, and a cup-shaped plunger fixed to one end of the push rod and covering the core. The inner cylindrical surface of the cup-shaped plunger is tapered to converge toward the bottom of the plunger. The push rod position is adjusted by bringing the tip of the push rod into contact with a screw member threaded into a hole in a cylindrical portion extending from the center for a cover of the electromagnet portion. The push rod axial position is adjusted by inserting a ring between the mutually confronting tips of the push rod and a distal column portion of the spool valve.