Turbine Case Coupling via Threaded Interface
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Solution Overview
Problem
Aircraft engine flanges experience high thermal gradients and stress, leading to bending or cracking, and the use of tightly tolerance-manufactured bolts to prevent clocking issues increases costs and the risk of human error during assembly.
Innovation Solution
A system for selectively coupling cases with threads of different orientations and a nut that engages with both, providing anti-rotation and alignment, along with seals and an insulation ring to reduce stress and eliminate the need for specific bolts and tight tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bolts are manufactured to tight tolerances to prevent clocking, then alignment precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent introduces an interface mechanism as an intermediary between the first and second cases. This interface includes alignment features and anti-rotation features that actively manage the coupling alignment, replacing the passive reliance on tight bolt tolerances. The interface acts as a mediator that ensures proper positioning without requiring the bolts themselves to be manufactured to extremely tight tolerances, thereby reducing manufacturing cost while maintaining alignment precision.
2Adaptability or versatility
If bolts of different lengths are used in different locations for bracket attachment, then adaptability is improved, but the risk of human error increases
Solution Approach 1:
The patent segments the coupling system into distinct functional components: the first case, the second case, the interface mechanism, and the bracket attachment system. By separating the bracket attachment function from the main coupling mechanism, the design allows brackets to be attached at various locations without affecting the core coupling operation. This segmentation enables adaptability while reducing assembly error risk, as each segment can be independently configured and verified.
Solution Approach 2:
The interface mechanism serves multiple functions: it provides alignment, prevents rotation, enables coupling, and supports bracket attachment at various locations. This multi-functionality means that a single interface design can accommodate different bracket configurations without requiring different bolt lengths, thereby maintaining adaptability while reducing assembly error risk through standardization.
3Strength
If a bolted flange is used to couple cases, then structural strength is improved, but thermal gradient stress causes bending or cracking
Solution Approach 1:
The patent introduces an interface mechanism as an intermediary between the first and second cases that replaces the traditional bolted flange connection. This interface is designed to better accommodate thermal gradient stresses through its structural design, which may include features like stress distribution elements, flexible connection elements, or geometric configurations that reduce stress concentration. The interface maintains coupling strength while being more resilient to thermal stresses than a rigid bolted flange.
Data Source
AI summary
A first case includes a first plurality of threads, a second case includes a second plurality of threads, an interface provides at least one of anti-rotation or alignment with respect to the first case and the second case, and a nut includes a third plurality of threads configured to engage with the first plurality of threads and a fourth plurality of threads configured to engage with the second plurality of threads.