Abstract: A rotary two-way servovalve provides a continuously variable orifice size in response to an input rotation while minimizing actuation torque. The valve is comprised of a cylindrical spool which is fitted to and rotates within a bore in a body. Fluid is fed into an axial hole in the spool through an inlet groove and cross holes and is metered out through one of a pair of diametrically opposed metering slots depending upon the angle of rotation. The second slot is provided to balance the pressure forces on the spool. Other features are a pivot which provides the axial location of the spool in the body while also sealing the spool, and a drain hole to prevent pressure from moving the spool axially. The valve is intended to be driven by an electrical rotary actuator such as a step motor, servo motor, or a limited angle torque motor.

Abstract: A rotary two-way servovalve provides a continuously variable orifice size in response to an input rotation while minimizing actuation torque and providing an orifice area, and thus flow, proportional to the input rotational angle. The valve is comprised of a cylindrical spool which is fitted to and rotates within a bore in a body. An axial hole in the spool terminates at one end and is closed at the other end by a plug. An inlet groove at one location along the outside of the spool communicates through radial holes with the axial hole, and this inlet groove is fed fluid under pressure from an inlet hole in the body. A cross hole, which also intersects the axial hole, feeds high pressure fluid to an opposed pair of outlet slots, one of which is positioned to intersect with an outlet port in the body to varying degrees, depending on the angular position of the spool. The second, identical, outlet slot faces the opposite side of the bore so as to balance the side loads on the spool from varying pressures.