Fuel control system for gas turbine engines

Claim 1

IN A FUEL CONTROL SYSTEM FOR A GAS TURBINE ENGINE HAVING AN ADJUSTABLE FUEL FLOW CONTROL VALVE, SAID FUEL FLOW CONTROL VALVE BEING CONTOURED IN ORDER THAT THE LOG OF THE FUEL FLOW IS PROPORTIONAL TO THE STROKE OF SAID VALVE, THERMAL COUPLE MEANS RESPONSIVE TO THE ACTUAL EXHAUST GAS TEMPERTURE OF SAID ENGINE FOR PROVIDING A SIGNAL SUBSTANTIALLLY REPRESENTATIVE THEREOF, SAID THERMOCOUPLE SIGNAL INHERENTLY LAGGING CHANGES IN THE ACTUAL EXHAUST GAS TEMPERATURE, PICK-OFF MEANS RESPONSIVE TO THE POSITION OF SAID FUEL FLOW CONTROL VALVE FOR PROVIDING A SIGNAL IN ACCORDANCE THEREWITH, HIGH PASS FILTER MEANS RESPONSIVE TO SAID PICKOFF SIGNAL FOR PROVIDING A RATE SIGNAL IN ACCORDANCE WITH THE RATE OF CHANGE THEREOF, SAID HIGH PASS FILTER MEANS HAVING A TIME CONSTANT WHICH PROVIDES A COMPENSATING SIGNAL THAT COMPENSATE FOR THE LAG IN SAID THERMOCOUPLE SIGNAL, AND MEANS FOR COMBINING SAID THERMOCOUPLE SIGNAL