Self-Retained Vane Linkage Using Single-Shear Bell Crank Studs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing double-shear designs in variable vane assemblies of gas turbine engines require numerous parts, leading to increased costs and assembly time due to multiple shear interfaces and frictional wear, which complicates the connection of multiple linkages.
Innovation Solution
A self-retained linkage system is introduced, where bell cranks are coupled to a self-retained linkage via a stud that is rotatably received in an opening, reducing the number of shear interfaces to a single interface between each bell crank and the linkage, eliminating the need for additional bolts and bushings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a double-shear design is used to connect linkages, then structural strength is improved, but the number of parts and assembly complexity increases
Solution Approach 1:
The patent combines the bolt and bushing into a single integrated stud component. The stud directly connects the bell crank to the linkage without requiring separate bushings, thereby reducing the number of parts while maintaining the structural strength through direct metal-to-metal contact and simplified load path.
Solution Approach 2:
The patent extracts and eliminates the bushing component from the traditional double-shear design. By removing the bushing and using the stud directly, the design reduces part count and simplifies assembly while still providing the necessary structural connection between linkages.
2Reliability
If a double-shear design is used with bolts and bushings, then wear control is improved, but assembly time and costs increase
Solution Approach 1:
The bolt and bushing are merged into a single stud component that performs both functions: providing structural connection and controlling wear through its hardened surface. This integration eliminates the need for separate assembly steps for installing bushings, thereby reducing assembly time while maintaining wear control capabilities.
3Force
If multiple shear interfaces are used, then load distribution is improved, but frictional wear and complexity increase
Solution Approach 1:
The patent removes the intermediate bushing that created additional friction surfaces. The direct stud-to-linkage connection eliminates unnecessary frictional interfaces while maintaining adequate load distribution through the strengthened stud design and optimized geometry.
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 reduces the number of parts and assembly time, decreases costs, and minimizes potential tolerance stack-up issues by simplifying the interface between bell cranks and the self-retained linkage, while maintaining structural integrity and reducing wear.
Implementation Method 1
A double-shear design (clevis and plate) is used at every interface between the linkages. A double-shear design requires a bolt and a means to retain the bolt. Also, two surfaces of each of the double shear interfaces are subject to wear and frictional forces.
Data Source
AI summary
A variable vane assembly for a gas turbine engine, the variable vane assembly including: a plurality of vanes arranged into a plurality of stages, each one of the plurality of vanes being configured for rotation about an axis through movement of a vane arm secured to each one of the plurality of vanes at one end and a sync ring of each one of the plurality of stages at another end; and a plurality of bell cranks operably coupling the sync ring of each one of the plurality of stages to a self-retained linkage via a stud of each one of the plurality of bell cranks, the stud of each one of the plurality of bell cranks being rotatably received in a corresponding opening of the self-retained linkage in an alternating fashion such that only a single shear interface is provided between each one of the plurality of bell cranks and the self-retained linkage.