BOAS Spring Clip Mounting for Torque-Resistant Sealing

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Solution Overview

Problem

Segmented BOAS mounts lack a full hoop structure, preventing an interference fit and resulting in inadequate sealing due to torque exerted by the BOAS on the mount, which traditional mounting systems cannot effectively resist.

Innovation Solution

A spring clip with a clip body featuring a first end bend to engage with the BOAS retaining structure and a second end bend to wrap around the BOAS mounting hook, along with an axial retaining feature forming a living hinge, is used to securely mount the BOAS in segmented systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a segmented BOAS mount is used instead of a full hoop structure, then the device complexity is reduced and ease of manufacture is improved, but the sealing reliability deteriorates due to inability to maintain interference fit under torque

Engineering Contradiction:
Improvemount structureVSAvoidsealing reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The BOAS mount is divided into segmented sections rather than a continuous full hoop structure. This segmentation reduces manufacturing complexity and allows the mount to be assembled in sections, while the spring clip provides the necessary radial force to maintain sealing contact between the segments and the BOAS aft face.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spring clip changes the mechanical parameters by providing dynamic radial force that maintains the interference fit condition. The spring mechanism adjusts the contact pressure between the segmented mount and the BOAS, ensuring reliable sealing despite the reduced structural continuity of the segmented design.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If a segmented BOAS mount is used, then ease of manufacture is improved, but the torque resistance capability deteriorates, causing rotation of the mount and loss of positive contact

Engineering Contradiction:
Improvemount assemblyVSAvoidtorque resistance
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The spring clip acts as a flexible elastic element that wraps around the BOAS and engages with the segmented mount. This flexible structure provides continuous radial force to resist torque-induced rotation, maintaining the mechanical connection between the segmented mount sections and the BOAS without requiring a rigid full hoop structure.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The spring clip introduces a dynamic element to the otherwise static segmented mount system. The spring mechanism can dynamically adjust to torque variations, maintaining constant radial pressure on the BOAS to prevent mount rotation and ensure sustained positive contact under varying operational loads.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If traditional mounting systems are used with segmented mounts, then device complexity is reduced, but the sealing performance deteriorates due to inadequate resistance to torque from BOAS contact

Engineering Contradiction:
Improvemounting systemVSAvoidgas path leaks
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The spring clip modifies the contact pressure parameter between the segmented mount and the BOAS aft face. By maintaining optimal interference fit pressure, the spring ensures that the segmented mount structure achieves adequate sealing performance to prevent gas path leaks, despite the reduced structural continuity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The spring clip serves as an intermediary element between the segmented mount and the BOAS. It mediates the interaction by providing the necessary radial force to maintain sealing contact, allowing the segmented mount structure to achieve reliable sealing without requiring complex additional mounting components.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 spring clip effectively resists torque and maintains a positive contact between the BOAS and the aft face seal, preventing gas path leaks and ensuring reliable sealing in all operational conditions.

Implementation Method 1

a spring clip for mounting a blade outer air seal (BOAS) to a BOAS mount... The spring clip effectively resists torque and maintains a positive contact between the BOAS and the aft face seal

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3088689B1Blade outer air seal spring clips
Publication Date: 2025.04.16 RTX CORP
  • EP3088689B1 patent drawingFigure 1
  • EP3088689B1 patent drawingFigure 2~3
  • EP3088689B1 patent drawingFigure 4~5

AI summary

A spring clip (200) for a blade outer air seal, BOAS (300) includes a clip body (201) defining a first end (203) configured to operatively engage with a BOAS retaining structure (301) on a BOAS and a second end (205) configured to engage with at least one of a mounting hook (303) of a BOAS and a BOAS mount (400).