Geared Engine Flex Support With Axial Retention Stops

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Solution Overview

Problem

Turbomachines, such as gas turbine engines, face significant axial movement issues during extreme events like fan blade loss or bearing failure, which existing support structures fail to adequately retain the geared architecture, leading to undesirable movements.

Innovation Solution

A support assembly comprising a flex support with a bellow, secured to an engine static structure, and featuring first and second members that are circumferentially aligned and spaced apart during normal operation but engageable during extreme events to limit axial movement of the geared architecture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If relatively compliant support structures are used to accommodate normal movement, then ease of operation is improved, but reliability deteriorates during extreme events

Engineering Contradiction:

Improveaccommodation of normal movementVSAvoidaxial retention during extreme events

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The support structure transitions from a static compliant design to a dynamic system that adapts its stiffness characteristics. During normal operation, the compliant support allows movement. During extreme events, the first and second members engage to create a rigid constraint, dynamically changing the structural behavior based on operational conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The first and second members are pre-positioned and designed to engage automatically when extreme axial forces occur. The stop feature is预先 designed at a specific axial distance, so when the geared architecture moves beyond this predetermined limit during extreme events, the members engage to prevent further movement.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If first and second members are spaced apart during normal operation, then ease of operation is improved, but reliability deteriorates during extreme events

Engineering Contradiction:

Improvenormal operation freedomVSAvoidaxial movement limitation during extreme events

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The axial spacing between the first and second members creates a dynamic system that is non-intrusive during normal operation but becomes active during extreme events. The members transition from a spaced-apart configuration to an engaged configuration, providing reliability only when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The first and second members are positioned to preemptively prevent excessive axial movement before it can occur. The stop feature is designed at a predetermined axial distance to engage and counteract extreme axial forces before they can cause damage or disengagement.

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If the stop feature is positioned at a predetermined axial distance, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:

Improvepredetermined axial positioningVSAvoidadditional retention members

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The retention system is segmented into distinct functional components: the compliant support structure for normal operation, the first member attached to the static structure, the second member attached to the geared architecture, and the stop feature. This segmentation allows each component to be optimized independently while maintaining overall system simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a complex active control system to prevent excessive movement, the invention uses a passive mechanical stop that engages only when needed. The simplicity of the stop feature contrasts with the complexity of active control systems, achieving reliability through mechanical ingenuity rather than complex control mechanisms.

Inventive Principle:

Principle #13The other way round (Inversion)

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 support assembly effectively limits axial movement of the geared architecture during extreme events, preventing disengagement of the fan section from the engine, thereby maintaining structural integrity.

Implementation Method 1

A flex support is secured to the engine static structure and includes a bellow

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS8517670B1Gas turbine engine geared architecture axial retention arrangement

Publication Date: 2013.08.27 RTX CORP

AI summary

A support assembly for a geared architecture includes an engine static structure. A flex support is secured to the engine static structure and includes a bellow. A support structure is operatively secured to the flex support. A geared architecture is mounted to the support structure. First members are removably secured to one of the engine static structure and the flex support and second members are removably secured to the support structure. The first and second members are circumferentially aligned with one another and spaced apart from one another during a normal operating condition. The first and second members are configured to be engageable with one another during an extreme event to limit axial movement of the geared architecture relative to the engine static structure.