초록 ▼

A fuel control system for gas turbine aeroengine includes an overspeed limiter unit operative to limit fuel flow when engine speed exceeds a predetermined safe value. It is conventional for such overspeed limiters to be activated only in the event of an overspeed, so as to obviate the possibility th

A fuel control system for gas turbine aeroengine includes an overspeed limiter unit operative to limit fuel flow when engine speed exceeds a predetermined safe value. It is conventional for such overspeed limiters to be activated only in the event of an overspeed, so as to obviate the possibility that the limiter unit may fail unnoticed while the unit is dormant, the invention utilises the limit unit as an active part of the fuel control system on a continuous basis. Specifically, the overspeed limiter unit is used to control the pressure drop across a fuel metering unit as a function of engine speed, except when it is actually performing its overspeed limiting task. Specific means of accomplishing this are disclosed. In this way, any failure in the limiter unit will be immediately apparent due to its effect on the functioning of the system, and appropriate action can be taken.

대표청구항 ▼

A fuel control system for a gas turbine aeroengine, including: (a) pump means for supplying pressurized fuel to the engine; (b) an electronic main fuel control unit for producing a fuel demand signal; (c) fuel metering means for metering the pressurized fuel to the engine in accordance with the fuel

A fuel control system for a gas turbine aeroengine, including: (a) pump means for supplying pressurized fuel to the engine; (b) an electronic main fuel control unit for producing a fuel demand signal; (c) fuel metering means for metering the pressurized fuel to the engine in accordance with the fuel demand signal a pressure drop thereby being created across the fuel metering means; (d) fuel recirculation means for recirculating through the pump means any fuel already pumped thereby but not passing through the fuel metering means; said recirculation means including valve means for controlling the amount of fuel being so recirculated; and (e) hydromechanical overspeed limiter means for detecting when engine rotational speed exceeds a predetermined value indicative of an overspeed and limiting fuel flow to an amount sufficient to prevent said overspeed; wherein said hydromechanical overspeed limiter means comprises means for controlling the magnitude of said fuel metering pressure drop such that said pressure drop is continuously variable as a predetermined function of engine rotational speed throughout normal non-overspeed operation of the engine, said means for controlling the magnitude of said fuel metering pressure drop comprising means responsive to said fuel metering pressure drop and said engine speed for controlling operation of said recirculation valve means such that if the fuel metering pressure drop varies from that demanded by the engine speed in accordance with said predetermined function, the amount of fuel being recirculated is varied so as to vary the fuel flow through the fuel metering means by an amount sufficient to restore the pressure drop to the correct value with respect to the engine speed in accordance with said function.