Aviation Electric Ltd.

Allied Corporation

David J Hawes

A method and apparatus for acceleration limiting a gas turbine engine (10) is disclosed. A proportional fuel control (11) regulates the fuel flow Wf from a hydromechanical unit (36) based upon an error signal E representing the difference between a demanded speed signal Nd and an actual speed signal Ng. The demanded speed signal Nd is generated by an integrator (32) as the time integral of the difference between the demanded signal Nd and a scheduled speed signal Ngs. Additionally, the difference signal is limited between an upper limit A1 and a lower limit D1 prior to the integration by a comparator (28) and a limiter circuit (30). The acceleration limit, A1 is generated as a function of a nondimensional parameter ratio (dN/dt.times.N)/Wf.

Method and apparatus for acceleration limiting a gas turbine engine

An acceleration limit reset circuit (38, 40, 42, 44) is disclosed for a closed loop fuel control (11) of a gas turbine engine (10). The closed loop control includes a comparator circuit (28) which compares an acceleration term Ngs-Nd to a limit value Al and if the scheduled acceleration (Ngs-Nd) is in excess of the limit, regulates the rate of change of the engine speed to the limited value Al. The acceleration limit Al is scheduled by an accel/decel limiter circuit (30) as substantially equivalent to the surge line of the engine. The acceleration limit reset circuit (38, 40, 42, 44) is provided for modifying the acceleration limit Al during special operating conditions of the engine (10) by a signal RRS.

Acceleration limit reset

A fuel control apparatus (34) for a gas turbine engine (10). The fuel control apparatus (34) meters fuel flow Wf according to an electrical signal (Wf/Pc, E) indicative of the desired fuel/air ratio of the engine as scheduled from the power lever angle (PLA) by a closed loop acceleration based electronic governor (26). The apparatus (34) mechanically multiplies the electrical signal (Wf/Pc, E) by the compressor discharge pressure (Pc) of the engine (10) to yield the fuel flow (Wf).

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Pierrefonds, Canada

David J Hawes