First-stage pilot valve

Abstract

A pilot valve configured to provide a control pressure within a dynamic fluid system, the pilot valve comprising: (a) a valve body having a supply port, a return port, and a control pressure port, the pressure control port in fluid communication with a subsequent valving component; (b) an axial bore formed in the valve body and in fluid communication with each of the supply, return, and control pressure ports; (c) a valve spool slidably supported within the axial bore of the valve body, the valve spool configured to control fluid flow through the supply, return, and control pressure ports, and to vary the rate of change of area of at least one of the supply and return pressure ports upon being displaced, thereby providing a variable resistance to fluid flowing therethrough and reducing the quiescent power of the pilot valve; and (d) means for displacing, in a selective manner, the valve spool within the axial bore about the supply, return, and control pressure ports to apportion fluid therethrough to provide a desired control pressure to the subsequent valving component. The pilot valve further comprises a feedback port formed in the valve body and in fluid communication with the control pressure port; and a feedback passage in fluid communication with the feedback port and a portion of the valve spool, the feedback passage configured to receive pressurized fluid therein to act against the valve spool to balance the forces acting on the valve spool from the motor.