Speed Reducer Connection Flexibility for Turbine Stress Control
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Solution Overview
Problem
The mechanical stability and efficiency of mechanical transmission devices in geared turbine engines are compromised due to differential dynamic movements of components, leading to stress accumulation and reduced lifespan, with existing solutions either increasing weight or being ineffective.
Innovation Solution
Implementing connection elements with specific radial flexibility ratios to distribute radial stresses optimally, reducing mechanical stresses and wear within the mechanical transmission device without increasing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the components of the mechanical transmission device are strengthened to withstand stresses, then the mechanical stability and lifespan are improved, but the mass increases significantly
Solution Approach 1:
The patent applies parameter changes by modifying the radial flexibility characteristics of connection elements. Specifically, it establishes that the radial flexibility of the first connection element (connecting fan shaft to mechanical transmission device) should be strictly less than 10% of the radial flexibility of the third connection element (connecting mechanical transmission device to casing), and strictly less than 4% of the radial flexibility of the second connection element (connecting turbine shaft to mechanical transmission device). This parameter optimization allows the mechanical transmission device to accommodate differential radial movements without requiring excessive strengthening, thus maintaining reliability while controlling mass.
2Reliability
If the stiffness of connection elements is reduced to limit stress accumulation, then the mechanical stability is improved, but the structural strength decreases
Solution Approach 1:
The patent applies local quality by differentiating the radial flexibility characteristics of different connection elements based on their specific functions and positions. The first connection element (fan shaft to mechanical transmission device) is designed with very low radial flexibility (less than 10% of third element and less than 4% of second element) to provide stable support, while the third connection element (mechanical transmission device to casing) maintains higher radial flexibility to accommodate overall movements. This localized optimization of flexibility properties allows the structure to manage stress accumulation effectively while maintaining necessary structural strength at critical locations.
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 approach extends the lifespan of the mechanical transmission device and improves the efficiency of the gas turbine engine by effectively managing differential component movements.
Implementation Method 1
a first connection element having a first end connected to the fan shaft and mounted on the first bearing, and a second end connected to the mechanical transmission device, the first connection element having a first radial flexibility
Data Source
AI summary
Disclosed is an assembly for a turbomachine, comprising: ⋅—a first connection element (9) having a first radial compliance (SR1); ⋅—a second connection element (10) having a second radial compliance (SR2); ⋅—a third connection element (11) having a third radial compliance (SR3); and ⋅—a fourth connection element (12) having a fourth radial compliance (SR4), wherein a ratio of the first radial compliance (SR1) to the third radial compliance (SR3) is strictly lower than 10%, and/or a ratio of the first radial compliance (SR1) to the second radial compliance (SR2) is strictly lower than 4%, and/or a ratio of the first radial compliance (SR1) to the fourth radial compliance (SR4) is strictly lower than 50%.