Geared Turbofan Shaft Support Layout for Gearbox Stiffness
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Solution Overview
Problem
Existing gas turbine engines with geared turbofan configurations face challenges in providing a suitable support for shaft arrangements driving the gearbox and propulsive fan, leading to inefficiencies and potential mechanical issues.
Innovation Solution
The gas turbine engine incorporates a gearbox device with a sun gear, planet carrier, and ring gear, connected to a turbine and propulsive fan via an input and output shaft device. The inter-shaft bearing system and rear carrier bearing device are positioned axially adjacent to the gearbox, enhancing support and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional shaft arrangement is used to drive the gearbox and propulsive fan, then the engine structure is simpler, but the mechanical support and stiffness are insufficient leading to inefficiencies
Solution Approach 1:
The shaft arrangement is segmented into multiple independent shafts (input shaft, output shaft, intermediate shafts) each with dedicated bearing supports. This segmentation allows each shaft to be optimized independently for its specific function while maintaining overall structural integrity and stiffness.
Solution Approach 2:
The bearing arrangements are positioned in multiple axial locations along the shafts, creating a three-dimensional support structure. This multi-dimensional bearing arrangement enhances mechanical support and stiffness by distributing loads across different spatial positions rather than relying on a single support point.
2Productivity
If the rotational speed from the turbine is not reduced, then the direct drive is simpler, but the overall engine efficiency is reduced
Solution Approach 1:
The gearbox integrates multiple gear stages and shafts into a single compact unit where the input shaft, output shaft, and intermediate shafts work together. This merging of components achieves the necessary speed reduction function while maintaining a space-efficient design suitable for the engine configuration.
Solution Approach 2:
Intermediate shafts and bearing arrangements serve as mediators between the high-speed turbine output and the low-speed propulsive fan input. These intermediary components enable the gradual reduction of rotational speed through multiple gear stages, improving overall engine efficiency while managing the complexity through functional decomposition.
3Strength
If bearings are positioned far from the gearbox, then the assembly is easier, but the load path and mechanical support are weakened
Solution Approach 1:
The bearing arrangements are pre-positioned in axially separated locations along the shafts during the design and manufacturing phase. This preliminary positioning ensures optimal load path alignment and mechanical support before final assembly, allowing for easier integration while maintaining enhanced structural strength.
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 configuration improves the mechanical support and efficiency of the gas turbine engine by reducing rotational speed and enhancing the load path from the turbine to the propulsive fan, thereby improving overall engine performance.
Implementation Method 1
The inter-shaft bearing system and rear carrier bearing device are positioned axially adjacent to the gearbox
Data Source
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AI summary
The invention relates to a gas turbine engine, in particular an aircraft engine, comprising: a turbine (19) connected via an input shaft device (50) to a gearbox device (30) having a sun gear (28), a planet carrier (34) having a plurality of planet gears (32) attached thereto, and a ring gear (38), the sun gear (28) is connected to the input shaft device (50), the planet carrier (34) or the ring gear (38) is connected to a propulsive fan (23) via an output shaft device (60) of the gearbox device (30), with a rear carrier bearing device (90) radially between the planet carrier (34) and a static structure (91) on the input side of the gearbox device (30), an inter-shaft bearing system (70) being positioned radially between the input shaft device (50) and the planet carrier (34) of the gearbox device (30). the input shaft device (50) having a high rigidity or the input shaft device (50) having a means for decreasing the rigidity, in particular a diaphragm section (51).