Variable-Pitch Vane Assembly Anti-Rotation Pin
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Solution Overview
Problem
The existing variable-pitch vane systems in gas turbine engines face challenges in compact installation due to the radial space constraints within the engine casing, particularly in the turbine section, where the sync ring and vane assembly require precise positioning to avoid case features while maintaining the ability to adjust vane pitch effectively.
Innovation Solution
The implementation of a variable-pitch vane assembly that includes a sync ring, a vane arm, and a pin with an anti-rotation notch, along with an anti-rotation spacer and bushing, which provides a threaded connection and a low-profile configuration to prevent pin rotation and secure the assembly, allowing for compact installation and efficient pitch adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional nut and bolt assembly is used to connect the pin, then the connection is secure, but the assembly complexity and radial space requirement increase
Solution Approach 1:
The patent combines multiple fastening functions into a single integrated pin assembly. The pin includes an integrated bushing, anti-rotation features (notch and spacer), and threading all in one component, eliminating the need for separate nuts and multiple bolts. This merging reduces assembly complexity while maintaining secure connection through the integrated design.
Solution Approach 2:
The pin serves multiple functions simultaneously: it provides rotational connection between vane arm and sync ring, prevents rotation through the anti-rotation notch and spacer, provides threading for secure attachment, and includes a bushing for wear reduction. This multi-functionality eliminates the need for separate specialized components, reducing overall assembly complexity.
2Ease of manufacture
If the sync ring is positioned radially outboard to avoid case features, then installation is feasible, but the radial space available for the vane assembly is reduced
Solution Approach 1:
The patent employs a nested arrangement where the pin is inserted through both the sync ring and vane arm, with the bushing nested within the pin structure. The anti-rotation spacer is positioned within the confined space between the pin head and the vane arm. This nesting allows multiple components to occupy minimal radial space while maintaining full functionality.
Solution Approach 2:
The patent transitions from a traditional radial arrangement to utilizing the axial dimension more effectively. The pin extends axially through both components, and the anti-rotation features are positioned axially rather than radially. This dimensional shift allows the assembly to fit within tighter radial clearances while maintaining installation feasibility.
3Adaptability or versatility
If the pin is allowed to rotate freely, then the vane pitch can be adjusted, but the pin may rotate unintentionally causing misalignment
Solution Approach 1:
The anti-rotation spacer acts as an intermediary element between the pin and the vane arm. It engages with the anti-rotation notch on the pin while simultaneously abutting the sync ring's outer surface. This intermediary provides controlled interaction - allowing intentional rotation for pitch adjustment while preventing unintentional rotation through the mechanical engagement of the notch-spacer-r ring system.
Data Source
AI summary
A variable-pitch vane assembly for a gas turbine engine includes a sync ring, a vane having a vane arm, and a pin installed through the sync ring and through the vane arm. The pin includes an anti-rotation notch located along a pin shaft. An anti-rotation spacer is engaged with the pin at the anti-rotation notch to prevent rotation of the pin. A turbine section of a gas turbine engine includes a turbine rotor and a turbine stator. The turbine stator includes one or more variable-pitch vane assemblies including a sync ring, a vane having a vane arm, and a pin installed through the sync ring and through the vane arm. The pin includes an anti-rotation notch located along a pin shaft. An anti-rotation spacer is engaged with the pin at the anti-rotation notch to prevent rotation of the pin.