Epicyclic Reduction Gear With Variable Ratio for Turbine Engine Adaptation
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Solution Overview
Problem
Current turbomachine technologies face limitations in adapting to varying flight phases and power requirements, particularly in helicopter applications, due to fixed reduction ratios and complex architectures, which restrict efficiency and reactivity.
Innovation Solution
An epicyclic reduction gear system with a third element that can be selectively secured to the stator and driven at controlled speeds, allowing for adaptive reduction ratios and optimized performance across multiple operating points, enabled by braking means and mechanical connection mechanisms for power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant reduction ratio is used in the transmission chain, then the engine architecture is simplified and responsiveness is improved, but the compressor efficiency deteriorates at partial loads and the engine cannot adapt to varying flight phases
Solution Approach 1:
The patent applies the dynamics principle by making the reduction ratio variable instead of fixed. The epicyclic gearbox incorporates a controllable element (such as a movable planet carrier or adjustable ring gear) that can change the effective number of gear teeth engaged, thereby continuously varying the reduction ratio according to flight conditions. This allows the engine to adapt to different flight phases while maintaining a relatively simple overall architecture without requiring multiple fixed-ratio gearboxes.
2Productivity
If a free turbine architecture is used, then compressor efficiency is optimized and pumping margin is improved, but the engine architecture becomes complex and responsiveness deteriorates
Solution Approach 1:
The patent merges the advantages of linked and free turbine architectures by combining a simplified linked turbine structure with a variable reduction ratio gearbox. The epicyclic gearbox allows the turbine to operate at optimal speeds for compressor efficiency while the variable gearing compensates for the lack of independent turbine speed control, effectively combining the benefits of both architectures without their respective drawbacks.
3Device complexity
If a linked turbine architecture is used, then responsiveness is improved and architecture is simplified, but compressor efficiency deteriorates at partial loads and adaptability is reduced
Solution Approach 1:
The variable reduction ratio gearbox dynamically adjusts the gear ratio to maintain optimal compressor operating conditions across different power settings. At partial loads, the gearbox modifies the reduction ratio to keep the compressor within its efficient operating range, thereby resolving the efficiency deterioration issue while preserving the simplified linked turbine architecture.
4Speed
If an epicyclic gearbox with constant reduction ratio is used, then the fan can rotate slowly with large diameter, but the gas generator cannot adapt to variations in intake requirements
Solution Approach 1:
The patent implements a variable reduction ratio epicyclic gearbox that allows the gas generator speed to vary independently of the fan speed. By making the reduction ratio adjustable, the system can adapt the gas generator operating point to match varying intake requirements while maintaining the desired slow fan rotation for high thrust efficiency.
Data Source
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AI summary
The invention relates to an aircraft turbine engine, including at least one rotary body comprising a compressor rotor and a turbine rotor connected to one another by a rotor shaft, the turbine engine being configured to drive a member by said shaft via an epicyclic reduction gear (32), said reduction gear including at least one first element (50) configured to be rotatably secured to said shaft, at least one second element (56) rotatably secured to said member, and at least one third element (52) which is configured to be selectively secured to a stator of the turbine engine and separated from said stator, characterised in that it comprises means (82, 84) for rotating said third element which are configured to drive said third element at a predetermined speed when it is separated from said stator.