Semi-Annular Retaining Ring for Low-Load Anti-Rotation

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Solution Overview

Problem

Internal retaining rings in gas turbine engines face challenges with high spring-back forces that complicate installation and cause excessive radial loads, leading to stress concentrations and reduced component lifespan, especially in applications with limited spacing between components.

Innovation Solution

A semi-annular internal retaining ring design with radially outward anti-rotation tabs and radially inward protruding tabs, featuring a 'moon-shaped' geometry with distinct centers of curvature, which reduces spring-back forces and facilitates easier installation by allowing deformation for fitting within tight spaces, and engages with anti-rotation features to prevent rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If internal retaining rings rely on internal spring-back forces to prevent rotation, then rotation prevention is achieved, but installation becomes difficult and excessive radial loads are produced

Engineering Contradiction:

Improverotation preventionVSAvoidinstallation difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The retaining ring is divided into a body portion and multiple radial tabs that can independently engage with grooves. This segmentation allows the tabs to provide anti-rotation functionality without requiring the entire ring to generate high spring-back forces, thereby easing installation while maintaining rotation prevention

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The radial tabs are designed with specific geometric features (curvatures matching groove profiles) that concentrate the anti-rotation function at localized engagement points rather than requiring uniform spring-back forces across the entire ring, reducing overall installation difficulty

Inventive Principle:

Principle #3Local quality

2Reliability

If internal retaining rings rely on internal spring-back forces to prevent rotation, then rotation prevention is achieved, but excessive radial loads are produced causing stress concentrations

Engineering Contradiction:

Improverotation preventionVSAvoidcomponent lifespan

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

By segmenting the retaining ring into a body and multiple radial tabs, the anti-rotation function is distributed across multiple discrete engagement points. This eliminates the need for high spring-back forces that cause excessive radial loads, thereby preventing stress concentrations and extending component lifespan

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The anti-rotation function is extracted from the spring-back mechanism and implemented through the radial tabs that engage with grooves. This separation allows rotation prevention without relying on high spring-back forces, thus avoiding excessive radial loads and stress concentrations on the retained component

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If internal retaining rings are designed with sufficient stiffness for spring-back forces, then rotation prevention is improved, but installation in tight spaces becomes difficult

Engineering Contradiction:

Improverotation preventionVSAvoidinstallation in tight spaces

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The retaining ring is segmented into a body and multiple radial tabs that can flex independently during installation. This allows the ring to be compressed into tight spaces without requiring the entire structure to be highly flexible, while still providing sufficient stiffness for rotation prevention through the engaged tabs

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The radial tabs are designed to be flexible during installation (allowing compression into tight spaces) but become rigid when engaged with the grooves. This dynamic behavior enables easy installation in tight spaces while maintaining rotation prevention functionality

Inventive Principle:

Principle #15Dynamics

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

The design enables easier installation, reduces stress concentrations, and provides consistent axial retention without relying on high spring-back forces, potentially extending the lifespan of components and minimizing the risk of scoring.

Implementation Method 1

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4083450A1Internal retaining ring for a rotating assembly in a gas turbine engine

Publication Date: 2022.11.02 PRATT & WHITNEY CANADA CORP

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AI summary

An internal retaining ring (70) for placement in a bore (31) of an outer component (30) of a rotating assembly (20) comprises a semi-annular body (71) having an outer circumferential surface (75) with a curvature defined about a first center of curvature (C1) and radially outward protruding anti-rotation tabs (72a) operable for engagement with a corresponding anti-rotation feature (36) of the outer component (30). An inner circumferential surface (76) of the semi-annular body (71) has radially inward protruding tabs (76a) circumferentially spaced apart around the inner circumferential surface (76). The radially inward protruding tabs (76a) have radially inner surfaces (76a1) concentric with the outer circumferential surface (75), and recessed portions (76b) between the radially inward protruding tabs (76a) and having curvatures defined about a second center of curvature (C2), the second center of curvature (C2) different from the first center of curvature (C1).