Centering Arrangement With Deformable Contact Element

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Solution Overview

Problem

Existing centering solutions for gas turbines with inner and outer casings face challenges due to differential radial expansion caused by materials with different expansion coefficients and operating temperatures, leading to increased interface size, part count, assembly time, and cost.

Innovation Solution

A centering arrangement featuring a ring-like inner and outer part with a centering contact element that can deform to compensate for differential radial expansion, utilizing a corrugated intermediate ring or matching non-circular contours to establish mechanical contacts and facilitate elastic deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If radial keys are introduced to cope with differential radial expansion, then centering is achieved, but a larger interface is required

Engineering Contradiction:

Improvecentering accuracyVSAvoidinterface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent employs a flexible membrane structure that can deform radially to accommodate differential thermal expansion between inner and outer casings. This membrane acts as a centering element that maintains concentricity while requiring minimal interface area, replacing rigid radial keys with a compliant thin-walled structure.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the geometric parameters of the centering interface by using a membrane with varying wall thickness and stiffness characteristics. This allows the membrane to adapt its deformation behavior to match the differential expansion rates of adjacent components while maintaining centering accuracy with reduced interface requirements.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If radial keys are introduced to cope with differential radial expansion, then centering is achieved, but an increased number of parts is necessary

Engineering Contradiction:

Improvecentering accuracyVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the centering function with the structural casing itself by integrating a membrane into the casing assembly. This eliminates the need for separate radial keys and associated mounting hardware, reducing the total part count while maintaining centering accuracy through the membrane's inherent geometric constraints.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The membrane structure serves multiple functions simultaneously: it provides centering, accommodates thermal expansion, and acts as a structural component of the casing. This multi-functionality eliminates the need for dedicated centering devices like radial keys, thereby reducing the number of parts required.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If radial keys are introduced to cope with differential radial expansion, then centering is achieved, but there is longer assembly time and higher cost

Engineering Contradiction:

Improvecentering accuracyVSAvoidassembly time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The membrane is pre-formed and pre-stressed during manufacturing to establish its centering geometry before installation. This preliminary preparation allows for rapid installation without requiring complex alignment procedures or multiple adjustment steps, thereby reducing assembly time while maintaining centering accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The membrane is designed as a simple, easily replaceable component with a straightforward installation and removal process. Its simple geometry and lack of complex fastening requirements enable quick assembly and disassembly, reducing labor time and associated costs compared to permanent radial key installations.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

This solution reduces the space and part requirements, speeds up assembly, and lowers costs while maintaining accurate centering under differential radial expansion conditions.

Implementation Method 1

which is able to deform in order to compensate for said differential radial expansion

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

parts are produced from different materials with different expansion coefficients, and/or operate at different temperatures

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10167739B2Centering arrangement of two parts relative to each other

Publication Date: 2019.01.01 ANSALDO ENERGIA SWITZERLAND AG

AI summary

A centering arrangement includes a ring-like inner part and a ring-like outer part, whereby the outer part surrounds the inner part in a concentric arrangement and with an interspace established between the outer part and the inner part, and whereby the outer part and the inner part are subject to a differential radial expansion. A centering contact element, procures a centering mechanical contact between the outer part and the inner part at a plurality of circumferentially distributed contact points, and is able to deform in order to compensate for differential radial expansion.