Power plants – Combustion products used as motive fluid – Combined with regulation of power output feature
Patent
1984-10-26
1985-11-12
Casaregola, Louis J.
Power plants
Combustion products used as motive fluid
Combined with regulation of power output feature
F02C 928
Patent
active
045519722
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fuel control systems and, more particularly, to an engine management system which may be coupled to a conventional fuel control system for an aircraft to add limited authority control which is capable, particularly on a multiple engine plane, of eliminating a substantial amount of flight crew work necessary to optimize thrust on takeoff and climb, synchronize engines at a desired level of temperature, engine pressure ratio, engine speed or air speed during climb or at cruise, and to provide fine tuning of engine controls at flight idle configuration during descent. In addition, the system can be used to optimize energy utilization through control of aircraft flight profile. As a result, significant fuel savings may be realized.
With respect to any vehicle engine, it is necessary to provide a fuel metering device responsive to a suitable control for metering sufficient quantities of fuel to the engine to keep the engine running and to provide motive power to the vehicle throughout its entire operating range. The control may be electronic, electro-mechanical, mechanical, hydraulic or of any other type suitable for responding to the inputs provided thereto to command the desired response from the fuel metering device.
The use of engines, and particularly gas turbine engines, in aircraft requires particular care in fuel control to maintain its operating range, without inadvertently causing damage to the engines or otherwise causing termination of operation of the engines. To this end, turbine engine fuel control systems have utilized numerous monitoring devices for sensing fan speed (N.sub.1), gas generator speed (N.sub.2) and turbine gas temperature (TGT) among other parameters and used this information to optimize engine performance.
However, even with such complex fuel control circuitry, it is necessary to closely monitor engine performance during the various flight modes and manually adjust the throttle levers for the engines so that specified engine conditions can be achieved during various operating modes of the aircraft.
During a typical flight, a substantial amount of throttle adjustment must be performed by the flight crew to obtain desired engine thrust levels without exceeding safe engine operating limits. For example, during takeoff, the throttles will generally be set so that each engine achieves the maximum thrust configuration. During initial climb, the engines are preferably set to achieve maximum continuous thrust without exceeding the engine's maximum permissible limits, e.g. temperature or engine pressure ratio. During cruise operation, the engines may be controlled to maintain precise temperatures or engine pressure ratios or aircraft cruising speeds while the engines are prevented from running out of speed synchronization. During landing, the flight idle throttle lever positions must be continually monitored and adjusted to achieve the necessary thrust level as atmospheric conditions rapidly change upon reducing altitude.
Systems have been provided in the prior art which have monitored limited numbers of engine or flight parameters to advise the crew of the correct throttle settings or to provide one or more of the control functions outlined above, such as engine pressure ratio or air speed compensation of engines or synchronizing or synchrophasing of engines to the performance of a designated master engine. Such prior art systems generally operated to control engine performance in one of two ways. One type of system integrates the desired functions into a complex fuel control computer, preferably of the electronic type. Another type of control device utilizes an autothrottle system.
Both approaches suffer substantial drawbacks. Autothrottle systems are very expensive and carry substantial size and weight penalties associated with the powerful drive motors required to maneuver the throttle levers for fuel control. Additionally, automatic control with an autothrottle is difficult or impossible under conditions where the pilot maintains his hand upon the throttle le
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Casaregola Louis J.
McFarland James W.
Miller Albert J.
Miller Leslie S.
The Garrett Corporation
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