Direct solenoid operated valve with minimal tolerance accumulation

Claim 1

A directional flow control valve including a valve body having a valve spool bore in which is slidably mounted an elongated valve spool provided with a plurality of annular valve members for sliding sealing engagement with a plurality of lands in said valve bore, and wherein said valve spool is shiftable directly by a solenoid in a short stroke, between a first position and a second position, to control the flow of pressurized air through the valve in one direction and the exhaustion of air through the valve in another direction, characterized in that: (a) the valve includes means engageable with one end of said valve spool for moving said valve spool to said first position; (b) a solenoid is mounted on said valve body for direct engagement with said valve spool to move it to said second position, and the solenoid includes a pole piece having one end seated against one end of the valve body adjacent one end of said valve bore, and the tolerances for forming the valve spool lengthwise, and the valve bore through the valve body lengthwise, and the length of the solenoid pole piece and push rod are determined from said one end of the valve body; (c) the solenoid includes means for resiliently biasing said pole piece to the position seated against the valve body; (d) the other end of said valve spool is seated against said solenoid pole piece when the valve spool is in said first position; (e) said solenoid includes an armature movable into shifting engagement with said other end of the pole piece when the solenoid is energized; and, (f) a pusher rod is movably mounted through an axial bore in said solenoid pole piece, and it has one end in operative engagement with said other end of said valve spool and the other end in engagement with said armature, whereby, when said solenoid is energized, said armature moves the pusher rod and the valve spool through a short stroke, from said first position with the annular valve members in sealing engagement with a first set of said lands to said second position with the annular valve members in sealing engagement with another set of said lands, and when said solenoid is de-energized, said means engageable with said one end of said valve spool moves the valve spool back to the first position.