Gas Turbine Hanger Pin Retention System
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Solution Overview
Problem
The existing hanger system for gas turbine engine liner panels, which separates core and bypass flows, faces issues with retention due to accelerated wear and mechanical disengagement of spring clips, leading to potential failure under thermal variance and vibratory conditions.
Innovation Solution
A hanger system with a pin and clip assembly that allows transverse movement of the pin within a hanger, secured by a fastener, and an eye-bolt attached to both the liner panel and static structure, providing positive retention and minimizing wear through controlled engagement and reduced impact stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring clips are used to retain the pin in the hanger system, then the liner panel can be retained and thermal variance accommodated, but the spring clips suffer from accelerated wear and mechanical disengagement
Solution Approach 1:
The patent removes the spring clips from the retention system entirely. Instead of using spring clips that engage with the pin, the design uses a clevis-shaped hanger with a slot that receives the pin, and a separate retainer component that positively retains the pin in the slot without requiring spring-loaded clips. This extraction of the problematic spring clip element eliminates the wear and disengagement issues while maintaining retention functionality.
Solution Approach 2:
Instead of using spring clips that actively clamp onto the pin, the patent inverts the approach by using a slot-receive-retain mechanism where the pin is received in a slot and then positively retained by a separate retainer component. This inversion from active clamping to passive receiving with positive retention eliminates the wear mechanisms associated with spring clips while maintaining the necessary retention under thermal variance and vibratory conditions.
2Strength
If the pin is fixed rigidly in the hanger, then retention is strong, but thermal variance cannot be accommodated and stress increases
Solution Approach 1:
The patent implements a dynamic retention system where the pin can move longitudinally within the slot of the clevis-shaped hanger to accommodate thermal expansion and contraction of the liner panel. The slot provides a controlled path for thermal movement, while the retainer component ensures the pin remains engaged. This dynamic arrangement allows the system to maintain strong retention while accommodating temperature variations without generating excessive stress.
Solution Approach 2:
The retention system is segmented into distinct functional components: the clevis-shaped hanger with the slot provides the movement pathway, the pin provides the connection, and the retainer component provides positive retention. This segmentation allows each component to perform its specific function - the slot accommodates thermal movement while the retainer maintains strong retention - resolving the contradiction between rigid strength and thermal flexibility.
3Device complexity
If spring clips are used for retention, then the system is simple, but the clips disengage mechanically under vibratory conditions
Solution Approach 1:
The patent inverts the retention approach from spring clips that rely on elastic deformation and friction to a positive mechanical retention system. The retainer component engages with the pin in a way that provides deterministic, vibration-resistant retention. This inversion from elastic/friction-based retention to positive mechanical engagement eliminates disengagement under vibratory conditions while maintaining reasonable system simplicity.
Solution Approach 2:
The retainer component acts as an intermediary element between the pin and the hanger structure. Rather than relying on spring clips to directly retain the pin, the retainer component mediates the connection by positively engaging the pin within the slot. This intermediary mechanism provides more reliable vibration resistance compared to direct spring clip engagement while keeping the overall system relatively simple.
Data Source
AI summary
A hanger system includes a pin with a head section which defines a pin axis. A clip assembly captures the head section to permit movement of the pin within a hanger in a direction transverse to the pin axis. A fastener which retains the clip assembly to the hanger.