Interference-Fit Compression Ring for Compressor Shroud Stress Relief

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Solution Overview

Problem

Existing compressor designs for micro-turbine alternators in systems like UAVs and electrically-powered suits face inefficiencies due to high centrifugal forces causing tensile stress on shrouded impellers, especially when manufactured via additive methods, which can exceed material strength.

Innovation Solution

A stress relieving compressor shroud compression ring is installed via an interference fit around the shroud to compress the impeller blades into the central shaft, reducing operational tensile stress by bridging the gap between material strength and operational stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the compressor shroud and blades are manufactured via additive manufacturing, then manufacturing complexity is reduced and design flexibility is improved, but tensile strength is insufficient to withstand high centrifugal forces at operational speeds

Engineering Contradiction:
Improvemanufacturing processVSAvoidtensile strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The solution combines additively manufactured compressor components (shroud and blades) with a separately manufactured compression ring to create a composite structure. The compression ring, made from material with superior tensile strength properties, reinforces the additively manufactured components that cannot achieve sufficient strength through additive manufacturing alone, allowing the system to withstand high centrifugal forces at operational speeds

Inventive Principle:
Principle #40Composite materials

2Strength

If the compression ring is installed via interference fit, then structural integrity is improved and stress relief is achieved, but assembly complexity increases

Engineering Contradiction:
Improvestructural integrityVSAvoidassembly process
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The compression ring is designed with predetermined dimensional tolerances and interference fit characteristics that enable direct installation onto the shroud without requiring additional fastening operations. The preliminary precision engineering of the interference fit interface allows the ring to be pressed into place and immediately provide stress relief, eliminating the need for subsequent assembly steps

Inventive Principle:
Principle #10Preliminary action

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 compression ring effectively reduces tensile stress on the shroud and blades, maintaining structural integrity and improving operational efficiency of the compressor at high rotational speeds.

Implementation Method 1

The compression ring being in an interference fit with the shroud. The compression ring is configured to apply a radially inward compressive force along one or more portions of the radially outward surface of the shroud

Methodology Applied
Scientific EffectInterference fit:

Implementation Method 2

The compression ring is configured to apply a radially inward compressive force along one or more portions of the radially outward surface of the shroud, the radially inward compressive is configured to compress the shroud and the plurality of blades into the central shaft

Methodology Applied
Scientific EffectCompressive force: Compression

Data Source

PatentEP4148281B1Stress relieving compressor shroud compression rings
Publication Date: 2025.08.13 HAMILTON SUNDSTRAND CORP
  • EP4148281B1 patent drawingFigure 1
  • EP4148281B1 patent drawingFigure 2
  • EP4148281B1 patent drawingFigure 3

AI summary

A compressor assembly (300) includes a compressor (144) including a central shaft (210) including an external surface (214), a shroud (220) extending circumferentially around the central shaft. The shroud including a radially inward surface (224) and radially outward surface (222) located opposite the radially inward surface. The external surface of the central shaft and the radially inward surface of the shroud are in a facing spaced relationship forming a core flow path (C) therebetween. The compressor also includes a plurality of blades (125) extending from the central shaft to the shroud. The compressor assembly also includes a compression ring (400) extending circumferentially around the shroud, the compression ring being in an interference fit with the shroud. The compression ring is configured to apply a radially inward compressive force (F1) along one or more portions of the radially outward surface of the shroud, the radially inward compressive is configured to compress the shroud and the plurality of blades into the central shaft.