Fail safe valve and multiplexed fluid control systems incorporating the same

摘要

A fail-safe second stage valve for controlling actuator movement upon power loss in a multiplexed fluid power control system. The second stage valve is interposed between a corresponding actuator and a fluid multiplexer to operate generally as integrating or amplifying device which regulates flow to the actuator. The second stage valve is provided with a dampening mechanism in the form of a bleed port to reduce fluid flow to the actuator. The bleed port bleeds off accumulated fluid received by the second stage valve over a predetermined range of valve positions. This changes the position of the valve and thereby reduces flow rate to the actuator. The multiplexed fluid power control system using the fail-safe second stage valve controls the flow to the corresponding actuator upon electrical power loss. The actuator may be used to open and close variable stator vanes in an aircraft gas turbine engine.