| 摘要 |
<p>Title: "Redundant Control Actuation System - Concentric Direct Drive Valve" A redundant control actuation system for an aircraft including an electro-mechanically controlled, hydraulically powered actuator for driving a main control valve of a servo-actuator control system. The actuator includes a tandem piston connected to the main control valve and a force motor driven tandem pilot valve axially movable in the piston for simultaneously controlling the differential application of fluid pressure from respective hydraulic systems on opposed pressure surfaces of respective piston sections to cause movement of the piston in response to relative axial movement of the pilot valve as long as at least one hydraulic system remains operative. The piston pressure surfaces are sized and arranged to minimize force unbalance on the piston due to pressure variations in the hydraulic systems. Also, a pilot valve centering spring device may be provided to minimize undesirable transient motions during system turn on and shut down. Upon failure or shut down of both hydraulic systems, a shut off valve sleeve concentric with the pilot valve moves axially in the piston to render the pilot valve inoperative and release fluid pressure from opposed, corresponding pressure surfaces of the piston sections to respective returns therefor through centering rate control orifices as the piston is moved to a neutral position by a centering spring device acting on the main control valve.</p> |
