Fan Drive Gear Controller for Variable Speed Reduction
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Solution Overview
Problem
Current gas turbine engine architectures, despite using geared systems for speed reduction, continue to seek improvements in thermal, transfer, and propulsive efficiencies.
Innovation Solution
A fan drive gear system with a geared architecture and a gear controller that varies the effective speed reduction ratio by controlling the rotation of the geared architecture relative to a static structure, allowing for adjustments from a fixed speed reduction ratio to a condition where the geared architecture rotates at a speed equal to the input shaft, thereby optimizing fan speed and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed speed reduction ratio is used in the geared architecture, then the structure is simple and reliable, but the engine cannot optimize fan speed for various operating conditions
Solution Approach 1:
The patent applies the dynamics principle by transforming the static geared architecture into a dynamic system. The gear controller enables the geared architecture to rotate relative to the static structure, allowing the speed reduction ratio to vary dynamically based on operating conditions. This is achieved through controllable elements that adjust the rotational state of the gear assembly, providing adaptability across different engine operating phases while maintaining a relatively simple mechanical structure.
2Adaptability or versatility
If the geared architecture rotates relative to the static structure, then the effective speed reduction ratio can be varied, but the structural complexity increases
Solution Approach 1:
The gear controller is designed as a multi-functional component that simultaneously provides structural support for the geared architecture and enables rotational control. This universal component performs multiple functions: supporting the gear assembly, controlling its rotation, and adjusting the speed reduction ratio, thereby reducing the need for separate dedicated components and minimizing overall structural complexity.
Solution Approach 2:
The patent merges the support function and control function into a single integrated gear controller assembly. The support structure and control mechanism are combined into one unified component that handles both structural support and rotational control, reducing the number of separate parts and simplifying the overall system architecture.
3Adaptability or versatility
If the geared architecture is fixed to the static structure, then torque transfer is efficient, but the fan speed cannot be optimized for different operating conditions
Solution Approach 1:
The system transitions from a static fixed connection to a dynamic controllable connection. The gear controller regulates the rotation of the geared architecture, allowing it to maintain efficient torque transfer when needed while enabling speed optimization for different operating conditions. The dynamic adjustment capability ensures that torque efficiency is maintained during critical operations while providing flexibility for optimization.
Data Source
AI summary
A fan drive gear system for a turbofan engine includes a geared architecture and a gear controller supporting the geared architecture and controlling rotation of the geared architecture relative a static structure.