Importance

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Abstract

A control system for an actuator used to position a control surface on an aircraft such as a horizontal stabilizer, including a source of pressurized fluid, a pressure control for establishing a predetermined pressure level that is substantially one-half source pressure, a blocker valve and at least one direction control valve for controlling the application of fluid pressures to the actuator. During idle periods, the blocker valve supplies substantially equal control pressures to the actuator so that the control system remains pressurized to substantially one-half source pressure. When the actuator is being energized, the direction control valve determines the direction of actuation and the blocker valve controls the fluid flow rate to and from the actuator to maintain a constant actuation rate regardless of load. A servo pressure a regulator monitors return flow across an orifice and adjusts the position of a blocker valve element in order to throttle both the input and return fluid flows to the actuator as a function of the return fluid flow rate so that movement in the actuator is effectively controlled even under overhauling loads.

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First Claim