Geared Turbine Fan Shaft Layout Without a Through Shaft
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Solution Overview
Problem
Gas turbine engines, particularly geared turbofan engines, require an efficient support system for shaft arrangements driving the gearbox and propulsive fan, as existing designs face challenges in mechanical load management and weight reduction.
Innovation Solution
A gas turbine design featuring a gearbox with a sun gear, planet carrier, and ring gear, utilizing an inter-shaft bearing system and carrier bearing system to manage axial loads, and an output shaft device with adaptive cross-sectional shapes to reduce weight and complexity, while ensuring efficient torque transmission without a through shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a through shaft is used to connect the turbine to the propulsive fan, then structural support and alignment are improved, but weight and complexity increase
Solution Approach 1:
The patent removes the through shaft from the system entirely. Instead of having a continuous shaft connecting the turbine to the propulsive fan, the design uses separate shafting arrangements with the turbine connected to a gearbox, which then connects to the propulsive fan via a different shaft. This extraction of the through shaft eliminates unnecessary weight while maintaining structural support through alternative means.
Solution Approach 2:
The patent segments the shafting arrangement into distinct sections: a turbine shaft connecting the turbine to the gearbox, and a separate output shaft connecting the gearbox to the propulsive fan. This segmentation allows each shaft to be optimized independently for its specific function and location, reducing overall weight while maintaining structural integrity through proper bearing support and alignment at each segment.
2Force
If the inter-shaft bearing system is positioned close to the gearbox device, then mechanical load management is improved, but space availability is reduced
Solution Approach 1:
The patent positions the inter-shaft bearing system in the radial direction between the input shaft device and the planet carrier, rather than only in the axial direction. This radial positioning allows the bearing system to be integrated into the existing radial space within the gearbox assembly, effectively utilizing the radial dimension to accommodate the bearing system without significantly reducing the axial space available for other components.
3Weight of moving object
If the output shaft device has an adaptive cross-sectional shape, then weight is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies adaptive cross-sectional shapes to specific sections of the output shaft device where weight reduction is most beneficial, rather than making the entire shaft complex. The cross-sectional shape varies along the length of the shaft to optimize the strength-to-weight ratio in different regions based on local loading conditions, while maintaining simpler geometries in regions where manufacturing is more critical.
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
The design enhances mechanical efficiency, reduces weight and costs by eliminating the need for a through shaft, and effectively manages mechanical loads, improving the overall performance and efficiency of the gas turbine engine.
Implementation Method 1
the inter-shaft bearing device comprises at least one ball bearing
Implementation Method 2
a carrier bearing system is located in the gas turbine radially between the input shaft device and a static structure, in particular a static rear cone structure, carrier bearing system in particular comprising at least one roller bearing
Data Source
AI summary
A gas turbine engine, in particular an aircraft engine, including: a turbine connected via an input shaft device to a gearbox device having a sun gear, a planet carrier having a plurality of planet gears attached thereto, and a ring gear, the sun gear is connected to the input shaft device, the planet carrier or the ring gear is connected to a propulsive fan via an output shaft device of the gearbox device, with an inter-shaft bearing system being positioned radially between the input shaft device and the planet carrier of the gearbox device.