Rotary servo valve

Abstract

An axial bore which extends through the spool and receives a control rod. Channels formed in the control rod cooperate with radial passageways in the valve spool. A pair of torsion rods extend axially from the control rod. One is coupled to a stepping or torque motor, the other is coupled to a rotatable drive member. An assembly for converting axial motion to rotary motion couples the valve spool to the drive member. In the preferred embodiment, this assembly takes the form of a rotatable threaded member secured to the end of the torsion rod and receiving a complementarily threaded end portion of the valve spool. One alternate embodiment comprises a pair of threaded rods extending from the spool, which drives a centrally disposed gear through a pair of complementarily threaded pinion gears. In another alternate embodiment a pressure control valve is achieved. Output fluid from the spool valve is applied to opposite sides of a threaded piston, which is spring biased by opposed compression springs. The piston is received upon a complementarily threaded shaft and axial motion of the piston is converted to rotary motion of the shaft. The shaft is coupled to an end of one of the torsion bars through a pair of gears.