Turbofan engine speed synchronizing arrangement

Claim 1

IN A TURBOFAN ENGINE INSTALLATION HAVING AT LEAST FIRST AND SECOND TURBOFAN ENGINES EACH OF THE TYPE HAVING A GAS GENERATOR ROTOR AND A SEPARATELY MOUNTED FAN ROTOR DRIVEN BY A FREE POWER TURBINE, A COMBINATION SPEED SYNCHRONIZING SYSTEM FOR THE GAS GENERATOR ROTORS AND THE SEPARATELY MOUNTED FAN ROTORS, RESPECTIVELY, COMPRISING: (A) TACHOMETER GENERATOR MEANS FOR GENERATING A FIRST SPEED DEPENDENT SIGNAL AS A FUNCTION OF THE FAN ROTOR SPEED OF SAID FIRST ENGINE, (B) TACHOMETER GENERATOR MEANS FOR GENERATING A SECOND SPEED DEPENDENT SIGNAL AS A FUNCTION OF THE FAN ROTOR SPEED OF SAID SECOND ENGINE, (C) TACHOMETER GENERATOR MEANS FOR GENERATING A THIRD SPEED DEPENDENT SIGNAL AS A FUNCTION OF THE SPEED OF THE GAS GENERATOR ROTOR OF SAID FIRST ENGINE, (D) TACHOMETER GENERATOR MEANS FOR GENERATING A FOURTH SPEED DEPENDENT SIGNAL AS A FUNCTION OF THE SPEED OF THE GAS GENERATOR ROTOR OF SAID SECOND ENGINE, (E) FREQUENCY DISCRIMINATOR AND SIGNAL SUMMING MEANS FOR DERIVING A FIRST SPEED ERROR SIGNAL PROPORTIONAL TO THE DIFFERENCE BETWEEN SAID FIRST AND SECOND SPEED DEPENDENT SIGNALS, (F) MEANS FOR VARYING THE AREA OF THE DISCHARGE NOZZLE ASSOCIATED WITH THE FREE POWER TURBINE OF SAID FIRST ENGINE RESPONSIVE TO SAID FIRST SPEED ERROR SIGNAL FOR ADJUSTING THE POWER OUTPUT OF THE FREE POWER TURBINE OF SAID FIRST ENGINE TO SYNCHORNIZE THE SPEEDS OF SAID FIRST AND SECOND ENGINE FAN ROTORS (G) FREQUENCY DISCRIMINATOR AND SIGNAL SUMMDING MEANS FOR DERIVING A SECOND SPEED ERROR SIGNAL PROPORTIONAL TO THE DIFFERENCE BETWEEN SAID THIRD AND FOURTH SPEED DEPENDENT SIGNALS, (H) FUEL CONTROL MEANS ASSOCIATED WITH AT LEAST ONE OF SAID ENGINES AND RESPONSIVE TO SAID SECOND SPEED ERROR SIGNAL TO MODULATE THE FUEL FLOW RATE TO SAID ONE ENGINE TO SYNCHORNIZE THE SPEEDS OF SAID FIRST AND SECOND GAS GENERATOR ROTORS, AND (I) CONTROL MEANS FOR OPERABLE IN RESPONSIVE TO A SHUTDOWN OF SAID SECOND ENGINE TO ADJUST SAID POWER MODUALTING MEANS TO A PRESELECTED CONDITION, SAID CONTROL MEANS INCLUDING A REFERENCE GENERATOR WHICH PRODUCES AN OUTPUT SIGNAL SCHEDULING SAID POWER MODULATING MEANS TO A PRESELECTED CONDITION DETERMINED BY SAID OUTPUT SIGNAL.