Rotating Machine Air Gap Constriction for Cooling

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Solution Overview

Problem

Existing electrically rotating machines face inefficiencies in cooling due to air flow escaping through the gap between the rotor and stator, leading to reduced heat transfer and potential for metallic particle abrasion and short circuits.

Innovation Solution

Narrowing the air gap by adjusting the radii of laminated core components and using additional elements like rings or flexible bands to minimize air flow loss and prevent metallic contact, while maintaining manufacturing simplicity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the air gap between rotor and stator is left wide, then manufacturing is easier and magnetic field stability is maintained, but air flow escapes through the gap reducing cooling efficiency

Engineering Contradiction:
Improvecooling efficiencyVSAvoidmanufacturing simplicity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies local quality by modifying only specific laminations at the air gap edges rather than changing the entire air gap structure. The outer radii of selected rotor laminations or inner radii of selected stator laminations are increased to create narrowing, while the rest of the machine maintains its original design. This localized modification prevents air flow escape at critical areas without requiring complex manufacturing changes throughout the entire machine.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If additional elements like rings are added to narrow the air gap, then air flow loss is reduced, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveair flow lossVSAvoidstructural complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent merges the air gap narrowing function directly into the existing lamination structure by modifying the radii of specific laminations. Instead of adding separate narrowing elements like rings or clips, the narrowing feature is integrated into the laminations themselves that already form the magnetic core. This combining approach reduces structural complexity while achieving the same air flow control effect.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If the radii of laminations are changed to narrow the air gap, then cooling efficiency improves, but magnetic field stability may be affected

Engineering Contradiction:
Improvecooling efficiencyVSAvoidmagnetic field stability
Core Design Contradiction:
Loss of energyVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by modifying only specific laminations at the air gap edges rather than changing the entire air gap structure. The outer radii of selected rotor laminations or inner radii of selected stator laminations are increased to create narrowing, while the rest of the machine maintains its original design. This localized modification prevents air flow escape at critical areas without requiring complex manufacturing changes throughout the entire machine.

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

Enhances cooling efficiency by retaining air flow within the machine, reducing the risk of metallic particle abrasion, and maintaining magnetic field stability with minimal manufacturing changes.

Implementation Method 1

The windings through which current flows heat up during operation of the electrically rotating machine and transfer a large part of their heat to the laminated core. Therefore, there is a need to cool these laminated cores. To cool the core, air can flow through cooling paths in the core to absorb the excess heat.

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2744075B1Electrically rotating machine
Publication Date: 2018.03.28 SIEMENS AG
  • EP2744075B1 patent drawingFigure 1~2
  • EP2744075B1 patent drawingFigure 3~4

AI summary

The rotating machine (1) has rotor and stator that is arranged with respective laminated cores (3,5). A fan (4) is provided for conducting air flow (11) to pass through cooling paths (15) into the laminated cores of rotor and stator. The cooling paths are interrupted by air gap (13) located between rotor and stator. The air gap is provided with constriction (7) so as to reduce air flow through the air gap. The constriction is produced by enlarging outer radii of laminated core (3) and/or by reducing inner radius of laminated core (5).