Aircraft Tail Cone Generator Rotor Coupling Thermal Expansion
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Solution Overview
Problem
Aircraft engines' tail cone mounted generators face challenges in accommodating thermal expansion and radial misalignment due to the thermal gradient, leading to axial growth and potential disconnection of the generator-to-engine coupling, which affects the efficiency and reliability of electrical power generation.
Innovation Solution
The implementation of a rotor coupling with both axial and radial coupling portions, including a transfer tube for fluid supply and an axial biasing member, allows for relative axial and radial displacement between the input and rotor shafts, maintaining sealing and rotational energy transfer while accommodating thermal expansion and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid coupling is used to connect the generator to the engine shaft, then rotational energy transfer is efficient, but the coupling cannot accommodate thermal expansion and radial misalignment, leading to potential disconnection
Solution Approach 1:
The patent applies the dynamics principle by making the coupling mechanism movable rather than rigid. The rotor coupling includes axial and radial coupling portions that can move relative to each other, allowing the system to adapt to thermal expansion and misalignment while maintaining rotational energy transfer. This dynamic capability resolves the contradiction between connection reliability and adaptability.
Solution Approach 2:
The patent applies parameter changes by allowing the coupling components to change their positional parameters (axial and radial positions) in response to thermal expansion and misalignment. The axial coupling portion and radial coupling portion can adjust their relative positions, changing the geometric parameters of the coupling system to accommodate environmental variations while maintaining reliable connection.
2Device complexity
If the generator is directly mounted on the engine shaft, then the structure is simple, but thermal gradient causes axial growth that disconnects the coupling
Solution Approach 1:
The patent applies segmentation by dividing the coupling into separate axial and radial coupling portions. This segmentation allows each portion to independently handle specific types of displacement (axial or radial), improving reliability without excessive complexity. The modular segmented structure enables targeted accommodation of thermal effects while maintaining overall coupling integrity.
Solution Approach 2:
The patent introduces intermediary coupling components (axial coupling portion and radial coupling portion) that mediate between the engine shaft and rotor shaft. These intermediary elements absorb thermal expansion and misalignment, protecting the primary connection from disconnection while maintaining a relatively simple overall structure.
3Loss of energy
If sealing engagement is maintained between rotating shafts, then rotational energy transfer is efficient, but thermal expansion causes disconnection
Solution Approach 1:
The patent applies dynamics by creating a dynamic sealing interface that moves with the shafts. The axial and radial coupling portions maintain sealing engagement while being capable of axial and radial movement, respectively. This dynamic sealing approach maintains rotational energy transfer efficiency while accommodating thermal expansion-induced displacements.
Solution Approach 2:
The patent employs flexible sealing elements (implied by the sealing engagement between moving parts) that can deform and maintain contact during axial and radial displacement. These flexible sealing components allow the system to maintain sealing and energy transfer efficiency while adapting to dimensional changes from thermal expansion.
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 configuration ensures reliable and efficient electrical power generation by allowing for axial and radial adjustments, preventing disconnection due to thermal expansion and maintaining sealing engagement, thus enhancing the operational stability of tail cone mounted generators.
Implementation Method 1
an axial biasing member arranged between the rotor shaft land and an input shaft land of the input shaft
Implementation Method 2
accommodating thermal expansion and radial misalignment due to the thermal gradient, leading to axial growth
Data Source
AI summary
Aircraft engines include an engine housing, a core assembly arranged within the engine housing and comprising an engine shaft arranged axially within the engine housing extending in a forward-aftward direction, and a tail cone assembly attached to an aft end of the engine housing. The tail cone assembly includes a tail cone housing and an aircraft machine arranged within the tail cone housing the aircraft machine comprising a rotor shaft. An input shaft is configured between the engine shaft and the rotor shaft and a rotor coupling configured to sealing connect the rotor shaft and the input shaft, the rotor coupling configured to providing sealing engagement between the rotor shaft and the input shaft during at least one of relative axial displacement and relative radial displacement between the rotor shaft and the input shaft.