Jacketed Rotating Machine Vacuum Dead Volume

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Solution Overview

Problem

Existing sleeved rotating machines, such as magnetic bearings and electric motors, face challenges in maintaining hermeticity and preventing deformation due to internal overpressure caused by leaks, which can lead to explosive atmospheres and reduced maintenance intervals.

Innovation Solution

Incorporating a dead volume within the metal protective enclosure that is evacuated to a pressure below atmospheric before closure, using a hermetic plug or welding, to store migrating gases and prevent overpressure-induced deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a thin jacket is used to protect the magnetic bearing components, then the protective enclosure can be made compact and lightweight, but the jacket becomes susceptible to deformation under internal overpressure

Engineering Contradiction:

Improveprotective enclosure volumeVSAvoidjacket resistance to deformation

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The dead volume is created and evacuated to vacuum before the hermetic closure of the protective enclosure. This preliminary action establishes a pressure buffer that prevents future overpressure deformation of the thin jacket during operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The evacuated dead volume acts as a cushioning chamber that absorbs migrating gases before they can create dangerous overpressure. The vacuum state provides a safety margin that protects the thin jacket from deformation even when leaks occur during operation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the protective enclosure is sealed hermetically, then component protection is improved, but any leaks create internal overpressure that can deform the jacket and fill the air gap

Engineering Contradiction:

ImprovehermeticityVSAvoidinternal overpressure deformation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The dead volume is evacuated to vacuum before hermetic sealing. This preliminary vacuum state creates a pressure buffer that prevents future overpressure deformation even when leaks occur, allowing the hermetic seal to maintain reliability without the harmful effects of overpressure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The migrating gases that would normally cause harmful overpressure are instead directed into the evacuated dead volume. The vacuum state causes these gases to be absorbed and stored safely, converting the harmful leak effect into a benign gas storage function

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If residual interstices are completely filled with molding resin, then hermeticity is improved, but manufacturing precision becomes difficult to guarantee

Engineering Contradiction:

ImprovehermeticityVSAvoidfilling completeness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Instead of attempting to completely fill all residual interstices with molding resin, the invention extracts the problem by creating a dedicated dead volume that intentionally remains unfilled. This isolated chamber captures migrating gases without requiring perfect resin filling of all internal voids

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The dead volume is created at a specific location within the protective enclosure where gas accumulation is most problematic. This localized approach addresses the hermeticity issue at the critical point without requiring universal perfection throughout the entire enclosure

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 solution significantly increases maintenance intervals and prevents the formation of explosive atmospheres, ensuring the sleeve remains undamaged during depressurization, thereby extending the operational life of the rotating machine.

Implementation Method 1

a dead volume (9, 109) in which there is a pressure below atmospheric pressure is formed inside the metal protective enclosure

Methodology Applied

Scientific EffectVacuum: Vacuum

Data Source

PatentEP2270958B1Encapsulated rotating machine and its method of manufacture

Publication Date: 2012.05.23 SKF MAGNETIC MECHATRONICS SAS

Figure 1~2
Figure 3~4

AI summary

A jacketed rotating machine is equipped with a rotor (101) in contact with a corrosive, acidic or particle-carrying gaseous atmosphere, and a functional electrical assembly such as a magnetic bearing comprising a rotor armature (106) integral with the rotor (101) and placed in the gaseous atmosphere and a stator armature (104) integral with a fixed support (102) and placed opposite the rotor armature (106), the stator armature (104) comprising at least one winding (142, 143) and a ferromagnetic body (141) placed in a metallic protective enclosure comprising a solid part integral with the fixed support (102) or merged with it, a thin jacket (103) and a hermetic passage (108) for a wiring (108a) supplying the windings (142, 143).An overmolding resin (107) fills residual internal gaps left in the ferromagnetic body (141), the windings (142, 143) and the wiring (108a) and a dead volume (109) in which a pressure lower than atmospheric pressure prevails is provided inside the metallic protective enclosure (102, 103, 108).