Turbine engine fuel control

Claim 2

A turbine engine fuel supply system comprising: a fuel metering valve having an inlet adapted to be connected to the outlet of a fuel pump and an outlet adapted to supply fuel to a burner assembly of the engine, said fuel metering valve including an orifice plate therein and a movable valve element including means thereon slidable across said orifice plate for varying flow through said orifice plate between the inlet and outlet of said valve, a shaft connected to said movable valve element, a lever connected to one end of said shaft, means for limiting arcuate movement of said lever and said valve element between minimum flow stop and maximum flow stop positions, metering valve servo means having a first axially movable stem and differential piston means therein connected to said first axially movable stem, said first differential piston means responsive to compressor discharge pressure, means including an orifice for bleeding pressure from said first differential piston means to condition said servo means to position said first axially movable stem to cause said lever to assume a maximum flow stop position where said movable valve element is moved a fixed arcuate amount with respect to said orifice plate, valve means for closing said bleed port to condition said differential piston means to position said movable valve element toward its minimum flow stop position, a pressure ratio sensor means having second differential piston means therein selectively responsive to a regulated pressure proportional to compressor discharge pressure and an intermediate pressure of the compressor, a second axially movable stem aligned coaxially of said first stem operated by the second differential piston means and connected to said valve means, means including a power lever for biasing the second axially movable stem against the control action of said sensor means, said power lever being positioned to establish a predetermined engine thrust, said sensor means being responsive to a reduced compressor discharge pressure produced by a change in engine thrust less than that set by the power lever to position said valve means to open said servo means bleed port thereby to condition said servo means to move said movable valve element towards its maximum stop position to increase fuel supply to a burner thereby to increaSe engine thrust to a level as preset by the power lever, said sensor means being responsive to an increased compressor discharge pressure produced by an engine thrust above a preset power level to move said valve means to close said servo means bleed port thereby to condition said servo means to shift said movable valve element toward the minimum flow stop position to reduce fuel supply to the engine burner thereby to return engine operation to a desired thrust level as preset by said power level.

Claim 3

A fuel metering system for a turbine engine including a compressor for supplying combustion air to a burner assembly for maintaining a predetermined engine thrust wherein fuel is supplied to the burner from a fuel pump, the improvement comprising: a fuel metering valve having an inlet adapted to be connected to the fuel pump and an outlet adapted to be connected to the burner, said metering valve including a fixed orifice plate interposed between the inlet and the outlet for controlling fuel flow therebetween and a movable valve element for varying the flow area through said orifice plate, said movable valve element having a minimum flow stop position and a maximum flow stop position, metering valve servo means including an operator coupled to said movable valve element for positioning said valve element between the minimum and maximum flow stop positions, said metering valve servo means including a pair of differential area pistons therein, means including one of said pistons forming a first pressurizable chamber, an inlet to said first pressurizable chamber to receive a compressor discharge pressure signal, means including a second one of said pistons for defining a second pressurizable control chamber, means for directing the compressor discharge pressure signal from said first chamber to said second chamber including an orifice therein for reducing the pressure signal from said compressor discharge into said second chamber, means for bleeding air from said chamber including a servo means bleed port, a bleed valve selectively opening and closing said bleed port for conditioning said servo means when said port is opened to produce a resultant force on said movable valve element to shift said movable valve element toward a maximum fuel stop position and to condition said servo means when the bleed port is closed to produce a resultant force on said movable valve element to return it toward its minimum flow stop position, said bleed valve being positioned by means including a pressure ratio sensor means including differential piston means therein, an axially movable operator stem connected to said differential piston means and to said bleed valve, said sensor differential piston means including a first pressurizable control chamber, an inlet to said pressurizable control chamber adapted to receive a pressure signal from an intermediate stage of a compressor, said differential piston means including a second pressurizable control chamber, means for directing a regulated pressure into said second chamber proportional to the compressor discharge pressure signal, said axially movable operator stem being biased in a first direction in response to pressurization of said control chambers, means including a power throttle lever for biasing said operator stem in an opposite direction to the bias of said pressurized control chambers, said differential piston means of said sensor means responding to pressure conditions of its first and second control chambers when the regulated proportional pressure is below that produced in response to a desired thrust setting of said power lever to condition said sensor means to position said operator stem to cause said bleed valve to open said bleed port thereby to condition said movable valve element towards the maximum flow position to increase engine thrust to return it to the power lever setting, said control chambers of said sensor means responding to compressor discharge and intermediate pressures as produced by reduced engine load to conditioN said operator to position said bleed valve to close said bleed port thereby to condition the differential piston means of said servo means to cause said movable valve element to move into a minimum flow stop position.

Claim 4

A fuel metering system for a turbine engine including a compressor for supplying combustion air to a burner assembly for maintaining a predetermined engine thrust wherein fuel is supplied to the burner from a fuel pump, the improvement comprising: a fuel metering valve having an inlet adapted to be connected to the fuel pump and an outlet adapted to be connected to the burner, said metering valve including a fixed orifice plate interposed between the inlet and the outlet for controlling fuel flow therebetween and a movable valve element for varying the flow area through said orifice plate, said movable valve element having a minimum flow stop position and a maximum flow stop position, metering valve servo means including an operator coupled to said movable valve element for positioning said valve element between the minimum and maximum flow stop positions, said metering valve servo means including a pair of differential area pistons therein, means including one of said pistons forming a first pressurizable chamber, an inlet to said first pressurizable chamber to receive a compressor discharge pressure signal, means including a second one of said pistons for defining a second pressurizable control chamber, means for directing the compressor discharge pressure signal from said first chamber to said second chamber including an orifice therein for reducing the pressure signal from said compressor discharge into said second chamber, means for bleeding air from said chamber including a servo means bleed port, a bleed valve selectively opening and closing said bleed port for conditioning said servo means when said port is opened to produce a resultant force on said movable valve element to shift said movable valve element toward a maximum fuel stop position and to condition said servo means when the bleed port is closed to produce a resultant force on said movable valve element to return it toward its minimum flow stop position, said bleed valve being positioned by means including a pressure ratio sensor means including differential piston means therein, an axially movable operator stem connected to said differential piston means and to said bleed valve, said sensor differential piston means including a first pressurizable control chamber, an inlet to said pressurizable control chamber adapted to receive a pressure signal from an intermediate stage of a compressor, said differential piston means including a second pressurizable control chamber, means for directing a regulated pressure into said second chamber proportional to the compressor discharge pressure signal, said axially movable operator stem being biased in a first direction in response to pressurization of said control chambers, means including a power throttle lever for biasing said operator stem in an opposite direction to the bias of said pressurized control chambers, said differential piston means of said sensor means responding to pressure conditions of its first and second control chambers when the regulated proportional pressure is below that produced in response to a desired thrust setting of said power lever to condition said sensor means to position said operator stem to cause said bleed valve to open said bleed port thereby to condition said movable valve element towards the maximum flow position to increase engine thrust to return it to the power lever setting, said control chambers of said sensor means responding to compressor discharge and intermediate pressures as produced by reduced engine load to conditioN said operator to position said bleed valve to close said bleed port thereby to condition the differential piston means of said servo means to cause said movable valve element to move into a minimum flow stop position.