Lateral Reduction Gearbox for Compact Gas Turbine Engines
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Solution Overview
Problem
Conventional reduction gearboxes for gas turbine engines are too large to be accommodated close to the engine core, leading to increased size and weight due to the need for multiple speed reduction stages, which conflicts with other critical components like the air intake.
Innovation Solution
A reduction gearbox design with a first gear reduction stage that transfers power laterally through transversely extending gear axes, creating a transverse gap and allowing the majority of speed reduction, and a second stage driven by the output of the first stage to further reduce speed, enabling a more compact configuration that can be placed closer to the engine core without obstructing air intake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional multi-stage reduction gearboxes are used to reduce high turbine speed to low propeller speed, then the required speed reduction ratio is achieved, but the gearbox size becomes too large to be accommodated close to the engine core
Solution Approach 1:
The patent transitions from a conventional axial arrangement of gear stages to a lateral/transverse arrangement where gear sets are positioned side-by-side rather than end-to-end. The input gear transfers power laterally to multiple speed reduction gear sets that are laterally spaced apart, utilizing the transverse dimension to achieve compact packaging while maintaining the required speed reduction ratio.
Solution Approach 2:
The speed reduction function is divided into multiple independent gear sets (first speed reduction gear set, second speed reduction gear set, etc.) that operate in parallel laterally. Each gear set handles a portion of the power transmission and contributes to the overall reduction ratio, allowing the system to achieve high reduction ratios without increasing axial length.
2Volume of stationary object
If the reduction gearbox is placed close to the engine core to reduce overall engine size, then engine compactness is improved, but spatial conflict occurs with components such as the air intake
Solution Approach 1:
By arranging gear sets laterally rather than axially, the patent creates vertical and lateral clearance that allows the air intake to be positioned above or around the gearbox without interference. This dimensional reorganization enables the gearbox to be mounted close to the engine core while maintaining compatibility with other engine components.
3Speed
If multiple speed reduction stages are added to achieve the required reduction ratio, then the speed reduction capability is improved, but the gearbox becomes heavier
Solution Approach 1:
The patent segments the power transmission path into multiple parallel lateral gear sets, each contributing to the overall reduction ratio. This segmentation allows for more efficient power distribution and reduces the load on individual gear sets, enabling the use of lighter components while achieving the required total reduction ratio.
Solution Approach 2:
By utilizing lateral spacing and transverse power transfer, the patent reduces the axial length and overall volume of the gearbox. This compact arrangement minimizes the amount of housing material and support structure required, thereby reducing the overall weight while maintaining the necessary speed reduction capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for a shorter and lighter gas turbine engine by eliminating the need for a separate drive shaft and integrating critical components like the air intake within the gearbox, reducing the overall axial length and weight.
Implementation Method 1
an input gear adapted to be driven by the turbine output shaft about a longitudinal input axis, the input gear transferring power to drive laterally spaced apart input speed gears about at least one transversely extending gear axis
Implementation Method 2
each input speed gear engaging an output speed gear to form a main speed reduction gear set, the engaged input and output speed gears of the main speed reduction gear set performing a majority of the reduction in the rotational speed
Data Source
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AI summary
The described reduction gearbox (20) of a gas turbine engine includes a first gear reduction stage (26) having an input gear (27) adapted to be driven by a turbine output shaft (19). The input gear (27) transfers power received from the turbine output shaft (19) laterally away from the input gear (27) to input speed gears (44). Each input speed gear (44) engages an output speed gear (48) to define a main speed reduction gear set, and the main speed reduction gear sets are laterally spaced apart from one another to define a gap. The gearbox (20) has a second gear reduction stage (25) driven by the output speed gear (48), the second stage (25) adapted to drive an engine output shaft.