Centrifugal Compressor Thrust Bearing Layout for Balanced Axial Load

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Solution Overview

Problem

Existing centrifugal compressors with identical thrust magnetic bearings may not effectively cancel the thrust load generated due to increased impeller rotation speed in a well-balanced manner.

Innovation Solution

A centrifugal compressor design where the second thrust magnetic bearing has a larger magnetic attraction force than the first thrust magnetic bearing, achieved by a larger outside diameter of the second thrust rotor compared to the first thrust rotor, allowing the magnetic attraction forces to balance the thrust load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If identical thrust magnetic bearings are used on both sides of the motor rotor, then the device complexity is reduced and manufacturing is simplified, but the thrust load cannot be canceled in a well-balanced manner

Engineering Contradiction:
Improvesimplicity of thrust magnetic bearing configurationVSAvoidthrust load cancellation balance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by configuring the second thrust magnetic bearing with a larger outside diameter than the first thrust magnetic bearing. This asymmetric design creates different magnetic attraction forces on each side of the motor rotor, allowing the thrust loads to be canceled in a well-balanced manner despite the asymmetric configuration. The larger second thrust magnetic bearing compensates for the thrust load imbalance caused by impeller rotation speed increases.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If the outside diameter of the second thrust rotor is increased to provide larger magnetic attraction force, then the thrust load cancellation is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvethrust load cancellation capabilityVSAvoiddifference in thrust magnetic bearing sizes
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by making each thrust magnetic bearing have different specifications tailored to its specific functional requirements. The first thrust magnetic bearing has a smaller outside diameter suitable for its position and load conditions, while the second thrust magnetic bearing has a larger outside diameter to provide the necessary magnetic attraction force for effective thrust load cancellation. This localized optimization of bearing dimensions ensures each component performs its function efficiently.

Inventive Principle:
Principle #3Local quality

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 design enables the cancellation of the thrust load in a well-balanced manner by using the differential magnetic attraction forces, while also facilitating efficient assembly and operation of the compressor.

Implementation Method 1

a magnetic attraction force of the second thrust magnetic bearing (60) toward the other side in the axial direction is larger than a magnetic attraction force of the first thrust magnetic bearing (50) toward the one side in the axial direction

Methodology Applied
Scientific EffectMagnetic attraction force: Magnetism

Data Source

PatentEP4119803B1Centrifugal compressor
Publication Date: 2024.10.02 DAIKIN INDUSTRIES LTD
  • EP4119803B1 patent drawingFigure 1
  • EP4119803B1 patent drawingFigure 2

AI summary

A first thrust magnetic bearing (50) is disposed between a motor rotor (12) and an impeller (21) in an axial direction. A second thrust magnetic bearing (60) is disposed, in the axial direction, on the other side in the axial direction relative to the motor rotor (12). A magnetic attraction force of the second thrust magnetic bearing (60) toward the other side in the axial direction is larger than a magnetic attraction force of the first thrust magnetic bearing (50) toward one side in the axial direction.