Compression Fitting Pin Retention for Anti-Rotation Sensor Leads

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Solution Overview

Problem

Compression fittings in gas turbine engines often lack anti-rotation pins, leading to follower rotation and potential damage or severing of sensor leads, and may also result in pins being ingested by the engine, posing a threat to components.

Innovation Solution

A compression fitting design that includes a body, follower, and pin, where the pin is coupled with the follower and cap nut, with the cap nut's internal edge overlapping the pin to prevent rotation, and various attachment methods such as tack welding, press fitting, or threading are used to secure the pin, ensuring rotational constraint during axial translation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an anti-rotation pin is installed in the compression fitting, then the follower is prevented from rotating and sensor leads are protected from damage, but the pin may separate from the fitting and be ingested by the engine

Engineering Contradiction:

Improveprotection of sensor leadsVSAvoidpin ingestion by engine

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The pin is nested within the cap nut, which acts as a retaining structure. The cap nut's internal edge radially overlaps the pin, creating a nested configuration where the pin is contained within the cap nut's internal cavity, preventing pin ejection while maintaining rotational constraint function

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The cap nut serves as an intermediary component between the pin and the external environment. It provides a retaining function by having its internal edge radially overlap the pin, acting as a mediator that prevents direct contact between the pin and engine components while allowing the pin to fulfill its anti-rotation purpose

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the pin is securely attached to the follower using methods such as tack welding, press fitting, or threading, then the pin remains constrained and prevents rotation, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvepin retentionVSAvoidassembly process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The pin is designed with self-retaining features including threaded portions that engage with the follower and a head portion that provides structural integrity. The combination of threading, press fitting capabilities, and tack welding provisions allows the pin to self-secure through multiple mechanisms, reducing the need for additional retention components while maintaining manufacturing flexibility

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The pin is designed with multi-functional capabilities: it provides rotational constraint through its constrained movement, structural support through its head portion, and self-retention through threaded engagement and press fit provisions. This multi-functionality consolidates multiple functions into a single component, simplifying the overall assembly while maintaining reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11680493B2Anti-rotation pin for compression fitting

Publication Date: 2023.06.20 RTX CORP

AI summary

A compression fitting is provided. The compression fitting may include a body, a follower, and a pin, and a cap nut. The follower may be disposed within an axial cavity of the body. The pin may be coupled with the follower. The cap nut may be coupled with the body. An internal edge of the cap nut radially overlaps at least a portion of a forward edge of the pin.