Centrifugal Compressor Axial Stopper and Auxiliary Bearing Design

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Solution Overview

Problem

Centrifugal compressors with magnetic bearings face challenges in restricting shaft movement in the axial direction when auxiliary bearings are used, as the distance between stoppers and auxiliary bearings varies with temperature changes, leading to potential contact issues and increased rotational resistance.

Innovation Solution

A centrifugal compressor design where a stopper is provided only for the first auxiliary bearing, with an axial magnetic bearing positioned closer to this auxiliary bearing, ensuring consistent distance and preventing contact between the stopper and auxiliary bearings, even during thermal expansion, using deep groove ball bearings for both auxiliary bearings to securely restrict axial movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If stoppers are installed on both ends of the shaft to restrict axial movement, then axial movement restriction is improved, but device complexity increases and contact with auxiliary bearings cannot be prevented

Engineering Contradiction:

Improveaxial movement restrictionVSAvoidnumber of stoppers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the stopper from one end of the shaft, keeping only one stopper at the first end while removing the stopper from the second end. This reduces device complexity while maintaining axial movement restriction functionality through the single remaining stopper working in conjunction with the first auxiliary bearing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The first auxiliary bearing serves multiple functions: it supports the shaft radially when displaced, restricts axial movement when the stopper contacts it, and prevents contact between the stopper and second auxiliary bearing. This multi-functionality eliminates the need for a separate stopper at the second end.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If the distance between stopper and auxiliary bearing is minimized to restrict thermal expansion movement, then axial movement control is improved, but contact between stopper and auxiliary bearing occurs during normal operation

Engineering Contradiction:

Improveaxial position controlVSAvoidrotational resistance

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention applies different clearance designs to different locations: a first clearance between the stopper and first auxiliary bearing that prevents contact during normal operation, and a second clearance between the stopper and second auxiliary bearing that prevents contact during thermal expansion. This local differentiation solves the contradiction between precision control and harmful contact.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention pre-establishes adequate clearances between the stopper and both auxiliary bearings to cushion against thermal expansion effects before they cause harmful contact. This beforehand cushioning prevents the stopper from contacting the second auxiliary bearing during operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Duration of action of stationary object

If stopper is positioned to prevent contact with second auxiliary bearing during thermal expansion, then component lifespan is improved, but axial movement restriction capability is reduced

Engineering Contradiction:

Improveauxiliary bearing lifespanVSAvoidaxial movement restriction

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The first auxiliary bearing acts as an intermediary that absorbs the thermal expansion movement. When the shaft expands thermally, the stopper contacts the first auxiliary bearing rather than the second, protecting the second auxiliary bearing from contact while still maintaining axial movement restriction capability through the first auxiliary bearing.

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

This design securely restricts shaft movement in the axial direction when supported by auxiliary bearings and prevents contact between the stopper and auxiliary bearings, maintaining operational efficiency and extending the lifespan of components.

Implementation Method 1

a shaft (2) that is rotatably supported by a magnetic bearing (6)

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the shaft and the like are heated to high temperatures. Therefore, during rotation, the shaft is extended in the axial direction

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10087945B2Centrifugal compressor

Publication Date: 2018.10.02 IHI CORP

AI summary

A centrifugal compressor (1) that includes: an auxiliary bearing (7) which supports a shaft (2), which is supported by a magnetic bearing (6), when the shaft (2) is displaced from a reference position; and a stopper (8) that is provided only for a first auxiliary bearing (7a) among the first auxiliary bearing (7a) and a second auxiliary bearing (7b), that is fixed to the shaft (2), and that restricts a movement of the shaft (2) in both directions in an axial direction by the stopper (8) being brought into contact with the first auxiliary bearing (7a).