Flexible Support Structure for Geared Gas Turbine Engine
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Solution Overview
Problem
In gas turbine engines, transverse deflections due to aero and maneuver loads cause misalignment of gear train elements, leading to efficiency losses and reduced component life due to increased stresses at journal bearings and gear teeth mesh.
Innovation Solution
A flexible support structure is integrated into the geared architecture, with specific transverse stiffness ratios between the flexible support, input coupling, and frame, allowing for controlled misalignment absorption and reduced stress concentrations, thereby maintaining torque transmission and gear alignment during maneuvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid frame supports the gear system, then structural stability is improved, but transverse deflections cause gear misalignment and increased stresses
Solution Approach 1:
The patent applies the dynamics principle by replacing the rigid frame with a flexible support structure that can dynamically adapt to transverse deflections. The flexible support has controlled stiffness properties that allow it to bend with the frame during aero and maneuver loads, maintaining gear alignment and reducing stresses on gear teeth and journal bearings.
Solution Approach 2:
The patent applies parameter changes by carefully selecting the stiffness parameters of the flexible support structure. The support is designed with specific transverse stiffness values that are optimized to accommodate frame deflections while maintaining adequate gear alignment. This involves changing the structural parameters (stiffness) of the support to resolve the contradiction between rigidity and flexibility.
2Reliability
If the flexible support transverse stiffness is reduced to accommodate deflections, then gear alignment is improved, but torque transmission capability may be compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the stiffness parameters of the flexible support and input coupling. The transverse stiffness is reduced enough to accommodate deflections and maintain gear alignment, while the longitudinal stiffness remains sufficient to transmit torque effectively. This selective parameter adjustment resolves the contradiction between flexibility for alignment and rigidity for power transmission.
Solution Approach 2:
The patent applies dynamics by designing the flexible support and input coupling with anisotropic stiffness characteristics - flexible in the transverse direction to accommodate deflections and maintain alignment, but sufficiently rigid in the longitudinal direction to transmit torque. This dynamic structural behavior allows the system to adapt to loading conditions while maintaining both alignment and power transmission 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
The flexible support structure reduces design loads by over 17%, increases system reliability, and extends component life by isolating gears from maneuver-induced loads, allowing the engine to 'float' and maintain constant torque transmission.
Implementation Method 1
a flexible support which at least partially supports the gear system, the flexible support defines a flexible support transverse stiffness (KFSBEND)
Data Source
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AI summary
A geared architecture (48) with a flex mount for a Fan Drive Gear System defined by a transverse stiffness relatonship.