Control of low compressor vanes and fuel for a gas turbine engine

Claim 1

For a gas turbine engine for powering aircraft having a pair of spools comprising a high pressure compressor/turbine combination and a fan/low pressure compressor and turbine combination solely aerodynamically coupled, a burner for combusting fuel and air for powering said turbines, fuel regulating means for regulating the flow of fuel to said burner and variable area vanes for regulating the air flow to said fan/low pressure, means for controlling said engine to operate on a low pressure compressor steady state operating line, the improvement comprising control means and including means for generating a signal indicative of N 1 lock responsive to low pressure compressor speed and the position of said power lever to regulate rapid accelerations and decelerations in response to a preselected low pressure compressor airflow parameter for controlling said variable vanes and said fuel regulating means, first means responsive to a plurality of engine and aircraft variables for generating a requested Wa signal, means responsive to the difference between N 1 lock and measured N 1 including a proportional and integral controller for adjusting said variable vanes to maintain said N 1 along a constant low pressure compressor speed selected by said N 1 lock and accelerate or decelerate said engine along a constant low pressure compressor speed to the targeted value selected by said power lever position, and additional control means responsive to said requested Wa signal for controlling said fuel regulating means and said variable vanes to return said engine to operate on said low pressure compressor steady state operating curve and timer means for actuating said additional control means upon reaching a predetermined time interval.