Bell Crank Sync Rod Assembly for Error-Proof Vane Alignment
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Solution Overview
Problem
Assembly issues in gas turbine engines, particularly with variable vanes, can lead to operational errors due to incorrect alignment or installation of components, affecting the functionality of the actuation mechanism.
Innovation Solution
A bell crank and bar assembly with perturbations and tabs on the sync rod ensures correct alignment by inhibiting incorrect installation, preventing the sync rod from being placed between the bell crank arms, thus mistake-proofing the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional assembly methods are used for variable vanes, then assembly flexibility is maintained, but assembly errors and incorrect alignment occur
Solution Approach 1:
The sync rod incorporates asymmetric features including a first tab extending from one end and a second tab extending from the opposite end, where the tabs have different geometries. The bell crank arms have corresponding asymmetric receiving areas with specific perturbations that only match the correct tab orientation. This asymmetric design ensures that the sync rod can only be assembled in the correct orientation, preventing assembly errors while maintaining straightforward assembly procedures.
Solution Approach 2:
The assembly mechanism employs self-checking features where the perturbations on the bell crank arms and the tabs on the sync rod automatically verify correct alignment during assembly. If the sync rod is attempted to be installed incorrectly, the tabs will not align with the receiving areas, providing immediate feedback and preventing wrong assembly without requiring external verification steps.
2Reliability
If error-proofing features are added to the assembly, then assembly correctness is improved, but device complexity increases
Solution Approach 1:
The sync rod incorporates asymmetric features including a first tab extending from one end and a second tab extending from the opposite end, where the tabs have different geometries. The bell crank arms have corresponding asymmetric receiving areas with specific perturbations that only match the correct tab orientation. This asymmetric design ensures that the sync rod can only be assembled in the correct orientation, preventing assembly errors while maintaining straightforward assembly procedures.
Solution Approach 2:
The design incorporates pre-configured geometric features (tabs and perturbations) that perform the error-checking function automatically during the assembly process itself, rather than requiring separate verification steps. The perturbations are预先 positioned on the bell crank arms to intercept incorrectly oriented sync rods before full assembly occurs, preventing errors at the source.
3Manufacturing precision
If simple assembly design is used, then device complexity is reduced, but assembly alignment precision deteriorates
Solution Approach 1:
The sync rod incorporates asymmetric features including a first tab extending from one end and a second tab extending from the opposite end, where the tabs have different geometries. The bell crank arms have corresponding asymmetric receiving areas with specific perturbations that only match the correct tab orientation. This asymmetric design ensures that the sync rod can only be assembled in the correct orientation, preventing assembly errors while maintaining straightforward assembly procedures.
Solution Approach 2:
The error-proofing features are localized to specific areas of the components rather than requiring complex overall design changes. The perturbations are concentrated at the ends of the bell crank arms where they interact with the tabs, providing precise alignment control at critical locations without adding complexity to the entire assembly structure.
Data Source
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AI summary
An assembly for use with a gas turbine engine (20) includes a block housing (74), a main bell crank (90), a bell crank (130), and a sync rod (94). The main bell crank extends between a main bell crank first end (100) and a main bell crank second end (102) that is connected to an actuator (72). The bell crank (130) extends between a bell crank first end (132) and a bell crank second end (134) that is pivotally supported by the block housing. The sync rod is connected the main bell crank first end and the bell crank first end. The sync rod defines a first tab (180) disposed proximate a first side and extends beyond a face of the sync rod.