CONTROL FOR AUXILIARY POWER UNIT

摘要

1411712 Automatic control of speed UNITED AIRCRAFT CORP 23 Jan 1973 [27 March 1972] 3380/73 Heading G3R [Also in Division F1] The speed of a free turbine in an aircraft auxiliary power unit which drives an alternator and an air compressor is kept constant by varying the fuel supplied to the gas generator and when an overtemperature condition is reached altering the air supplied to the compressor. In the control system shown the speed N2 of the free turbine and the speed N1 of the gas generator turbine shaft are sensed as voltages. The speed of the free turbine is compared with a desired speed value in comparator 32 and passes through proportional plus integral control 34 to generate a desired gas generator speed signal which passes to a least select arrangement when it is checked against a N 1 over temperature limit signal. If the limit is not exceeded the fuel supply to the gas generator is varied to alter its speed N1 to keep the speed N2 constant. If the limit is exceeded a signal is provided to the circuit 46 which causes actuator 22 to re-position the inlet guide vanes and alter the air supply to and thus the load on compressor (18).