Stall detector and surge prevention feature for a gas turbine engine
First Claim
1. A fuel control system for a gas turbine engine comprising:
- means for generating an actual speed signal proportional to the actual turbine speed of the gas turbine engine;
means for generating a scheduled speed signal proportional to a desired output power;
means for generating a demanded speed signal proportional to the time integral of a difference signal;
means for generating said difference signal proportional to the difference between said scheduled speed signal and said demanded speed signal;
means for generating an error signal proportional to the difference between said demanded speed signal and said actual speed signal;
means for controlling the fuel flow to the gas turbine engine as a function of said error signal;
means responsive to the actual speed signal and the demanded speed signal for generating a stall factor as a function of the difference between actual speed signal and the demanded speed signal and indicative of the degree of stall the engine is experiencing; and
means, responsive to the stall factor, to further control fuel flow to the gas turbine engine.
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Accused Products
Abstract
A proportional fuel 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 (Nh). The demanded speed signal (Nd) is generated by an integrator (32) as the time integral of the least of a plurality of acceleration terms (Aa, Ab, Ac, Ad) selected by a select low gate (38). The demanded acceleration term (Aa) is generated by junction (26) as the difference between the demanded signal (Nd) and a scheduled speed signal (Ngs). Stress acceleration terms (Ac, Ad) are generated by junctions (48, 50) and scheduling means (42, 44) which form stress limiter circuits. A stall acceleration term (Ab, is generated by a junction (46) and a scheduling means (40) which form a stall prevention feature.
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Citations
12 Claims
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1. A fuel control system for a gas turbine engine comprising:
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means for generating an actual speed signal proportional to the actual turbine speed of the gas turbine engine; means for generating a scheduled speed signal proportional to a desired output power; means for generating a demanded speed signal proportional to the time integral of a difference signal; means for generating said difference signal proportional to the difference between said scheduled speed signal and said demanded speed signal; means for generating an error signal proportional to the difference between said demanded speed signal and said actual speed signal; means for controlling the fuel flow to the gas turbine engine as a function of said error signal; means responsive to the actual speed signal and the demanded speed signal for generating a stall factor as a function of the difference between actual speed signal and the demanded speed signal and indicative of the degree of stall the engine is experiencing; and means, responsive to the stall factor, to further control fuel flow to the gas turbine engine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification