Dump control for turbine engine gate valve actuator

摘要

A gas turbine engine has a power turbine driven by gas flow across a nozzle arrangement that includes a partial admission gate valve therein that is movable into and out of overlying relationship with a limited number of vanes of the nozzle in order to control power output therefrom during part load operation of the engine. The gates are operated by a quick response pneumatic operator including an inlet to pressurizable control chamber having a movable control diaphragm therein with a valve element thereon movable into a closure relationship with a valve seat defining a dump opening in the valve and wherein a regulated source of pressure is applied against the movable diaphragm to hold it closed during a low power, road load mode of engine operation; an orifice in the valve element restricts flow into a pressurizable chamber formed in part by a movable power diaphragm to cause a controlled buildup of pressure therein and a slow velocity extension of the operator to position the gate in its part power position and wherein means are included to produce a slow rate retraction to avoid excess turbine temperatures and wherein dump means disconnect the regulated pressure from the operator inlet whereby the control diaphragm is snapped from its closure position on the dump opening valve seat so that the pressure bias on the power diaphragm is terminated to produce a quick spring biased opening of the gate valve from its partial blocking position to a full open position during a time period that prevents compressor surge as the gas turbine engine responds to a higher power demand wherein greater gas flows through the nozzle for increasing power output from the power turbine of the engine.