Auxiliary power and thrust unit

Details Auxiliary power and thrust unit Auxiliary power and thrust unit

1999-07-15

2001-06-19

Barefoot, Galen L. (Department: 3644)

Aeronautics and astronautics

Aircraft power plants

Auxiliary

C244S054000, C244S055000, C244S05300R

Reexamination Certificate

active

06247668

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to aeronautics and aircraft power plants, and more particularly, to the production of auxiliary power in aircraft.
BACKGROUND OF THE INVENTION
Auxiliary power units (APUs) are currently used on board aircraft to provide power to support pressurized hydraulic systems, environmental control systems, and electrical systems. APU support is generally provided while the aircraft is on the ground during loading and unloading of passengers. During flight, APUs are shut down or operated only during an emergency. APUs can be problematic in that they are a significant source of weight and cost to the aircraft, while only providing short term services while on the ground.
Thus, a need exists for a more efficient system of auxiliary power. The present invention is directed to fulfilling this need by describing an auxiliary power design that provides additional thrust for takeoff and climb in addition to providing power for running conventional auxiliary equipment.
SUMMARY OF THE INVENTION
An improvement to an aircraft is provided in the form of an aircraft auxiliary power and thrust unit located in the tail cone of the aircraft. The unit includes a turbofan engine, an air intake opening, an inlet duct extending between the air intake opening and the turbofan engine, a transmission assembly, and various auxiliary equipment. The engine includes a forward facing main turbine shaft. The air intake opening is located in the tail cone at a body station location forward of the engine. The transmission assembly includes a drive shaft mounted axially to the main turbine shaft and extends forward through the inlet duct through a sealed opening in the inlet duct. The auxiliary equipment is also located in the tail cone, forward of the turbofan engine. The transmission assembly is releasably connected to the auxiliary equipment. In a first operating mode, the engine is operated at a low setting to power the auxiliary equipment. In a second operating mode, the turbofan engine is used to provide thrust and also to drive auxiliary equipment. Various types of auxiliary equipment may be used with the present invention, such as a generator, a hydraulic pressure supply unit, and a compressor.
In one embodiment, the turbofan engine is sized to provide a maximum thrust of about 18000 pounds or less. In another embodiment, the engine provides maximum thrust in the range of about 8000 pounds to about 12000 pounds. The engine is installed in the tail cone using various bracket mounts located radially about the engine and attached to structural members in the tail cone. In one embodiment, the tail cone includes a pair of cowl doors that rotate outwardly about longitudinal axes located on each side of the tail cone; the cowl doors providing access into the tail cone for both installing and maintaining the engine.
In accordance with further aspects of this invention, a controller is electronically connected to the turbofan engine and the auxiliary equipment. During the first operating mode, the controller operates the engine at a low power setting and controls the auxiliary equipment to provide auxiliary services. During the second operating mode, the controller operates the engine to provide thrust and auxiliary power to the aircraft systems.


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