Gas Turbine Inner Shroud Assembly Segmented Retainer
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Solution Overview
Problem
The assembly of variable vane systems in gas turbine engines is complex due to numerous components and fasteners required to handle significant forces, making it difficult and costly.
Innovation Solution
An inner shroud assembly with retainer ring segments and shroud segments that align via alignment pins, eliminating the need for axial fasteners by using a ramped surface interface with the engine case for secure retention without bolts, reducing part count and assembly complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional variable vane systems use numerous components and fasteners to handle significant forces, then the system is operationally effective, but the assembly becomes complicated and costly
Solution Approach 1:
The retainer ring is divided into multiple segments (typically four 90-degree segments) that can be assembled independently around the shroud assembly. Each segment handles a portion of the retention function, allowing the system to maintain structural integrity while simplifying the assembly process and reducing the number of fasteners required.
Solution Approach 2:
The retainer ring segments, shroud segments, and alignment pins are combined into an integrated assembly unit that is installed as a complete package. This merging of components eliminates the need for numerous separate fasteners and reduces assembly steps, while still maintaining the ability to handle significant forces.
2Strength
If traditional variable vane systems use numerous fasteners to secure components, then the connection strength is sufficient, but the weight and cost increase
Solution Approach 1:
The retainer ring is segmented into multiple sections that can be installed without requiring numerous fasteners. The segments are retained by the shroud assembly structure itself, significantly reducing the total number of fasteners needed while maintaining adequate connection strength to handle operational forces.
Solution Approach 2:
The design replaces a traditional fastener-based mechanical connection system with a retention system that uses the geometry and interference fit of the segmented retainer ring and shroud assembly. This substitution eliminates the need for multiple bolts and fasteners, reducing weight while maintaining connection integrity.
3Reliability
If traditional variable vane systems use multiple fasteners and components, then the structural integrity is maintained, but the manufacturing cost and assembly time increase
Solution Approach 1:
The retainer ring segments, shroud segments, and alignment pins are designed to be assembled together as an integrated unit and installed as a complete package. This merging approach maintains structural integrity through the interlocking geometry of the components while dramatically reducing assembly time by eliminating multiple separate fastening operations.
Solution Approach 2:
The alignment pins are positioned and the retainer ring segments are pre-assembled with the shroud segments before installation into the engine case. This preliminary assembly ensures proper alignment and structural integrity are achieved before final installation, streamlining the overall assembly process and improving productivity.
Data Source
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AI summary
An inner shroud assembly (114) of a variable vane actuation system (118) for a gas turbine engine (20) includes a shroud assembly (130) comprising a multiple of forward shroud segments (140) and a respective multiple of aft shroud segments (142). A multiple of variable vanes (102) are rotationally retained at an inboard trunion (104) between the forward and aft shroud segments (140, 142) of the shroud assembly (130). A retainer assembly (132) includes a multiple of retainer ring segments (160) that retain the forward and aft shroud segments (140, 142) together. The inner shroud assembly (114) is assembled into an engine case (184) with an inboard extending feature (182) that engages with an axial interface feature (170) of each of the multiple of retainer ring segments (160).