Star Gear System Flexible Coupling Alignment
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Solution Overview
Problem
Recent gas turbine engine architectures face challenges in maximizing performance due to the need for efficient speed management and lubrication distribution between the fan section and the compressor sections, particularly in geared turbomachines where the fan and low-pressure compressor rotate at different speeds and directions.
Innovation Solution
A star gear system is introduced, including a sun gear attached to a fan drive turbine with a flexible input shaft, a ring gear attached to a fan drive shaft with a flexible coupling, and a carrier supported by a flexible carrier support, with a lubricant manifold in fluid communication to ensure proper alignment and lubrication across the geared architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a geared architecture is used to connect fan and turbine sections, then speed management is improved, but device complexity increases
Solution Approach 1:
A flexible coupling is introduced as an intermediary element between the fan drive shaft and the ring gear. This flexible coupling acts as a mediator that transmits rotational motion while accommodating misalignment and reducing the complexity of precise mechanical connections, thereby simplifying the overall geared architecture while maintaining speed management capabilities.
Solution Approach 2:
The patent employs flexible elements that can change their mechanical parameters (such as stiffness and alignment) in response to operational conditions. The flexible coupling and flexible carrier support allow for parameter changes that accommodate thermal expansion, vibration, and misalignment, reducing the complexity of rigid precision mounting while maintaining effective speed control.
2Stability of the object's composition
If multiple bearings are used to support fan section, then alignment is improved, but device complexity increases
Solution Approach 1:
A flexible carrier support is used to connect the carrier to the engine static structure. This flexible support acts as a compliant element that maintains alignment while accommodating thermal expansion and vibration, reducing the need for multiple rigid bearings and simplifying the support structure while preserving stability.
3Ease of operation
If flexible coupling is used to attach ring gear, then alignment tolerance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The flexible coupling is designed to change its mechanical parameters (stiffness, damping characteristics) based on operational conditions. This allows the coupling to accommodate alignment variations during operation while maintaining precise torque transmission, effectively balancing ease of operation with manufacturing precision requirements through adaptive parameter changes.
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 star gear system effectively manages speed differences and provides efficient lubrication, enhancing the performance and alignment of the geared architecture, thereby improving the overall efficiency and reducing noise in gas turbine engines.
Implementation Method 1
a sun gear attached to a fan drive turbine with a flexible input shaft
Implementation Method 2
a ring gear attached to a fan drive shaft with a flexible coupling
Implementation Method 3
a carrier supported by a flexible carrier support
Implementation Method 4
a lubricant manifold in fluid communication to ensure proper alignment and lubrication across the geared architecture
Data Source
AI summary
A gas turbine engine includes a fan section that includes a fan drive shaft. A star gear system for driving the fan section has a carrier mounted to a static structure to prevent the carrier from rotating. A ring gear is attached to a ring gear attachment point on the fan drive shaft. A first fan section support bearing supports a fan drive shaft and is mounted forward of the ring gear attachment point. A second fan section bearing supports the fan drive shaft and is mounted aft of the ring gear attachment point on the fan drive shaft. An outer race of the second fan section bearing is fixed relative to an engine static structure.