Method and apparatus for regulating fuel flow of a gas turbine engine

Claim 2

In a gas turbine engine hAving a fuel flow regulating valve means for regulating the working fuel flow rate of said engine, a method for controlling said valve means comprising comparing said working fuel flow rate with upper and lower limits of an acceptable range of working fuel flow rates determined in dependence upon the existing atmospheric pressure, temperature and the revolution speed of said engine, producing an appropriate digital signal representing that said flow rate is higher or lower than or within said acceptable range, and supplying a control signal to said valve means in accordance with said digital signal for moving the valve means to adjust said flow rate to enter into said acceptable range if the flow rate is higher or lower than said acceptable range or to approach a desired working fuel flow rate determined by the position of an accelerator pedal if the flow rate is otherwise within said acceptable range.

Claim 3

In a gas turbine engine having a fuel flow regulating valve means for regulating the working fuel flow rate to said engine a method for controlling said valve means in accordance with detected atmospheric pressure and temperature and a detected revolution speed of said engine, which method comprises producing a first signal substantially proportional to the working fuel flow rate regulated by said valve means, producing second and third signals respectively representing upper and lower limits of an acceptable range of fuel flow rates which is determined from the working fuel flow rate corrected in dependence upon said detected atmospheric pressure and temperature and the engine revolution speed corrected in dependence upon said detected atmospheric temperature, comparing said first signal with said second and third signals for producing a fourth or fifth signal when said first signal is higher than said second signal or lower than said third signal, respectively, producing a sixth signal in the concurrent absence of the fourth and fifth signals, producing a seventh signal which is substantially proportional to a desired working fuel flow rate for a selected position of an accelerator pedal, and producing an eighth or ninth signal representing a difference between said first and second or first and third signals respectively when said first signal is higher than said second signal or lower than said third signal for controlling said valve means to respectively reduce or increase the working fuel flow rate until said difference is eliminated or producing a tenth signal representing a difference between said first and seventh signal when said first signal is lower than said second signal and higher than said third signal for controlling said valve means to regulate the working fuel flow rate until the flow rate reaches said desired working fuel flow rate.

Claim 4

In a gas turbine engine having a fuel flow regulating valve means for regulating the working fuel flow rate to said engine a method for controlling said valve means in accordance with detected atmospheric pressure and temperature and a detected revolution speed of said engine, which method comprises producing a first signal substantially proportional to the working fuel flow rate regulated by said valve means, producing second and third signals respectively representing upper and lower limits of an acceptable range of fuel flow rates which is determined from the working fuel flow rate corrected in dependence upon said detected atmospheric pressure and temperature and the engine revolution speed corrected in dependence upon said detected atmospheric temperature, comparing said first signal with said second and third signals for producing a fourth or fifth signal when said first signal is higher than said second signal or lower than said third signal, respectively, producing a sixth signal in the concurrent absence of the fourth and fifth signals, producing a seventh signal which is substantially proportional to a desired working fuel flow rate for a selected position of an accelerator pedal, and producing an eighth or ninth signal representing a difference between said first and second or first and third signals respectively when said first signal is higher than said second signal or lower than said third signal for controlling said valve means to respectively reduce or increase the working fuel flow rate until said difference is eliminated or producing a tenth signal representing a difference between said first and seventh signal when said first signal is lower than said second signal and higher than said third signal for controlling said valve means to regulate the working fuel flow rate until the flow rate reaches said desired working fuel flow rate.

Claim 5

A method according to claim 2, wherein the corrected working fuel flow rate is determined as Square Root theta X delta X Fw where theta is a ratio of said detected atmospheric temperature versus a predetermined normal atmospheric temperature, delta is a ratio of said detected atmospheric pressure versus a predetermined normal atmospheric pressure and Fw is the detected working fuel flow rate.