Oval Pin Exhaust Liner Attachment for Gas Turbine Engines

Solution Overview

Problem

Securing and removing an exhaust liner from a gas turbine engine exhaust duct is challenging due to large tolerance stack-ups, complicated liner flow paths, and thermal warping, which complicates assembly and disassembly, especially in preventing undesired vibrations.

Innovation Solution

A pin with different dimensions is used, featuring an oval or cam-shaped profile that provides increased clearance for easier insertion and removal, and is rotated to engage the exhaust components securely, minimizing vibrations by increasing the cross-sectional dimension for loading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a round pin is used to secure the exhaust liner, then the assembly is simple, but the clearance is insufficient making assembly and disassembly difficult due to tolerance stack-ups and thermal warping

Engineering Contradiction:

Improveassembly and disassembly easeVSAvoidsecure attachment and vibration prevention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The pin cross-section is changed from a symmetric round shape to an asymmetric oval or cam-shaped profile. This asymmetric geometry provides directional clearance variation: larger clearance in the insertion/removal direction to accommodate tolerance stack-ups and thermal warping, while maintaining sufficient engagement in the radial direction to prevent vibrations during engine operation.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The pin is designed to be rotatable within the apertures of the brackets. By rotating the pin from an unsecured position (where the first dimension provides maximum clearance) to a secured position (where the second dimension provides loading and vibration prevention), the system dynamically transitions between assembly-friendly and operationally-secure states.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the pin is designed for easy insertion with large clearance, then assembly is simplified, but the loading capability to prevent vibrations is reduced

Engineering Contradiction:

Improveinsertion easeVSAvoidloading capability to prevent vibrations

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The oval or cam-shaped pin cross-section creates asymmetric clearance distribution: maximum clearance along the major axis facilitates easy insertion and removal, while the minor axis maintains sufficient material engagement to provide the necessary loading force for vibration prevention when the pin is rotated to the secured position.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The solution moves from a single-dimension clearance approach to a two-dimensional clearance variation by using an oval cross-section. The pin provides different clearances in different directions (major vs. minor axes), allowing easy insertion in one direction while maintaining structural integrity and loading capability in the perpendicular direction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If traditional pins are used, then the structure is simple, but thermal warping and tolerance stack-ups make removal and reassembly difficult

Engineering Contradiction:

Improvepin structure complexityVSAvoidremoval and reassembly ease

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The pin cross-section is changed from a symmetric round shape to an asymmetric oval or cam-shaped profile. This asymmetric geometry provides directional clearance variation: larger clearance in the insertion/removal direction to accommodate tolerance stack-ups and thermal warping, while maintaining sufficient engagement in the radial direction to prevent vibrations.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The pin is designed to be rotatable within the apertures of the brackets. By rotating the pin from an unsecured position (where the first dimension provides maximum clearance) to a secured position (where the second dimension provides loading and vibration prevention), the system dynamically transitions between assembly-friendly and operationally-secure states.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7866158B2Exhaust liner attachment arrangement

Publication Date: 2011.01.11 RTX CORP

AI summary

A turbine engine exhaust nozzle is disclosed that includes an exhaust liner having a first attachment structure. A liner support member includes a second attachment structure. A pin cooperates with the first and second attachment structures and is configured to secure the exhaust liner relative to the liner support member. The pin includes first and second dimensions that are different than one another. The pin is inserted into apertures provided by the attachment structures, in one example. The pin is oriented to position the first and second dimensions in a manner providing increased clearance within the apertures. The pin is rotated to load the components and firmly secure the liner to the liner support member.