Propeller gearbox

Details Propeller gearbox Propeller gearbox

2000-08-29

2001-07-24

Eldred, J. Woodrow (Department: 3644)

Aeronautics and astronautics

Aircraft power plants

Transmission of power

C244S065000, C074S66500G, C074S66500G

Reexamination Certificate

active

06264138

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to the design and construction of a gearbox for a gas turbine engine. More particularly, the present invention has one embodiment wherein the gearbox defines an inline two-stage reduction gearbox for a gas turbine turboprop engine.
Gas turbine turboprop engine designers generally couple a gear reduction gearbox with the engine in order to reduce the output shaft speed, and increase the torque delivered to an output device, such as a propeller. It is well known that gas turbine engines are high speed rotary equipment having components including an output shaft revolving at speeds from about 5,000 to 50,000 revolutions per minute. Sometimes, in order to harness the power from the output shaft of the gas turbine engine a gear reduction gearbox is coupled to the engine to decrease shaft rotation speed and increase output torque. Gear reduction gearboxes include gear sets therein for reducing the shaft speed during the transmission of power from the gas turbine engine to the propeller.
The application of gas turbine turboprop engines as a propulsion means for an aircraft often creates design parameter conflicts, such as the need for a durable long life gear train and the necessity to minimize the volume and weight of the respective engine. Prior designers of gas turbine engine gear reduction gearboxes have generally used multi-stage gearboxes to effectuate significant shaft speed reduction. Even with the variety of prior gas turbine gear reduction gearboxes there remains a need for an improved gear reduction gearbox. The present invention satisfies this need in a novel and unobvious way.
SUMMARY OF THE INVENTION
One form of the present invention contemplates an apparatus, comprising: an aircraft; at least one gas turbine turboprop engine coupled to the aircraft, the at least one gas turbine engine having an inlet end and an exhaust end, and a first member for transmitting power from the engine; a two stage reduction gearbox positioned proximate the inlet end and coupled to the engine, the gearbox having an input gear reduction stage coupled with and driven by the first member and a double helical output gear reduction stage coupled with a second member for transmitting power; and at least one propeller coupled to and driven by the second member.
Another form of the present invention contemplates an apparatus, comprising: an aircraft; at least one gas turbine turboprop engine coupled to the aircraft, the at least one gas turbine engine having an air inlet end and an exhaust end, and a first power transmission member for transmitting power from the engine; a gearbox positioned proximate the inlet end and coupled to the engine, the gearbox having two stages defined by an input gear reduction stage and an output gear reduction stage, the input gear reduction stage is coupled with and driveable by the first power transmission member and the output gear reduction stage is coupled with and drives a second power transmission member for transmitting power, the input gear reduction stage is defined by one of a spur or double helical gearing and the output gear reduction stage is defined by double helical gearing; and at least one propeller is coupled to and driven by the second power transmission member.
One aspect of the present invention contemplates a combination, comprising: an aircraft; at least one gas turbine engine coupled to the aircraft, the at least one gas turbine engine having an engine first end and an engine second end, and an engine output member for transmitting power from the engine; and a reduction gearbox positioned proximate the engine first end and coupled to the engine, the gearbox comprising: a mechanical housing; two gear reduction stages defined by an input gear reduction stage and an output gear reduction stage; a plurality of layshafts coupled with and having at least a portion thereof disposed within the mechanical housing, each of said plurality of layshafts having a layshaft first end and a layshaft second end; the input gear reduction stage includes a plurality of input gears, each of the plurality of layshafts having one of the input gears coupled to the layshaft first end and driven by the engine output member, the output gear reduction stage including a plurality of output gears, each of the plurality of layshafts having one of the output gears coupled to the layshaft second end, the plurality of output gears engaging and driving a gearbox output member that is coupled to a propeller; and wherein the plurality of input gears and the plurality of output gears eliminate thrust loading from the plurality of layshafts.
Another aspect of the present invention contemplates an apparatus, comprising: an aircraft; a gas turbine turboprop engine coupled to the aircraft, the gas turbine engine having an inlet end, an exhaust end, and a first power transmission member for transmitting power from the engine; a reduction gearbox positioned proximate the inlet end and coupled to the engine, the gearbox including: a mechanical housing; the gearbox having two stages of reduction defined by an input gear reduction stage and an output gear reduction stage, the input gear reduction stage defined by a first gear coupled to the first power transmission member and a plurality of second gears in meshing engagement with the first gear; the output gear reduction stage defined by a third gear and a plurality of fourth gears in meshing engagement therewith; a plurality of layshafts that are rotatably coupled with the mechanical housing, each of the plurality of layshafts having one of the plurality of second gears coupled at one end and one of the plurality of fourth gears coupled at the other end; the third gear coupled to and drives a second power transmission shaft having a propeller coupled thereto; and the input gear reduction stage is defined by one of a spur or double helical gearing and the output gear reduction stage is defined by a double helical gearing.
A preferred form of the invention includes torquemeter components inline with the engine output member and a power input gear of the first gear reduction stage.
The preferred form also mounts the input gears of the first stage layshafts in overhanging or cantilever manner from the input end of the layshafts, and the output gears of the second gear reduction stage in location between layshaft support bearings. The layshaft support bearings are located closer together and the output end bearing is relatively large in diameter, for better bearing load distribution and for longer bearing life.
One object of the present invention is to provide an improved propeller gear reduction gearbox.
These and other objects will become more apparent from the following description.


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Rolls-Royce Dart, Single Sheet Drawing.
T56/501 Series III Turboprop Engine, Two Drawing Sheets.

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