Directional valve

Abstract

A solenoid operated directional valve including a main section having a reciprocally mounted main fluid controlling valving member moveable between three positions in a housing. The housing defines at least two working ports and the main valving member controls fluid communication between a valve inlet and the two ports. An annular power piston assembly is coupled to the main valving member and effects movement in the valve member between three positions. A control member slidably supports both the annular piston and, an armature driven valving member which controls the communication of pressurized fluid to piston chambers. The piston defines at least one inlet associated with each chamber and housing structure defines restricted bleed passages through which pressurized fluid in the piston chambers is discharged. The control member defines passages which communicate with the piston inlets at predetermined positions of the piston and the armature driven valving member defines passages for controlling the communication of pressurized fluid to the control member passages depending on the position of the armature controlled valving member. When the armature controlled valving member is centered, the power piston is urged to the center position by both mechanical spring forces and fluid generated forces. In an alternate embodiment, a proportional valve is illustrated in which a power piston is used to incremental move a main valve member in response to movement in a control sleeve as effected by a servo motor and monitored by a linear variable differential transformer.