Stator Cooling Features Using Additive Manufacturing

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Solution Overview

Problem

Existing motor cooling designs face limitations due to high thermal contact resistance between aluminum cooling sleeves and steel stators, exacerbated by surface asperities that hinder intimate contact and reduce heat transfer efficiency.

Innovation Solution

The use of additive manufacturing techniques, such as cold spray and wire arc additive manufacturing, to directly deposit aluminum cooling features with varied geometries (discrete and continuous fins) onto the stator, reducing thermal contact resistance and enhancing convective heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a metal sleeve is shrunk fit around the stator to provide cooling, then convective heat transfer is improved, but thermal contact resistance increases due to surface asperities preventing intimate contact

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidthermal contact resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The cooling sleeve is segmented into discrete cooling elements (pins or plate fins) that can independently contact the stator surface, allowing each segment to conform to surface asperities and reduce overall thermal contact resistance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling sleeve incorporates localized contact features such as pins or fins that concentrate cooling capability at specific locations where thermal contact is most effective, while allowing other areas to accommodate surface irregularities

Inventive Principle:
Principle #3Local quality

2Strength

If a shrink fit connection is used to attach the cooling sleeve to the stator, then mechanical attachment is achieved, but thermal contact resistance increases due to asperities on the stator surface

Engineering Contradiction:
Improvemechanical attachmentVSAvoidthermal contact resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The cooling sleeve is divided into multiple discrete cooling elements (pins or plate fins) that can independently make contact with the stator surface, allowing each element to conform to local surface asperities while collectively providing both mechanical attachment and thermal contact

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The design changes the geometric parameters of the cooling sleeve to include features with smaller contact footprints (pins or fins) that can better accommodate surface roughness while maintaining adequate thermal and mechanical connection

Inventive Principle:
Principle #35Parameter changes

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 approach improves thermal management by reducing thermal resistance, enabling more efficient heat transfer and allowing for higher current density and power density in motors, while also providing an alternate torque transfer mechanism and potential weight savings.

Implementation Method 1

The use of additive manufacturing techniques, such as cold spray and wire arc additive manufacturing

Methodology Applied
Scientific EffectCold spray: Plasma Spray

Implementation Method 2

The use of additive manufacturing techniques, such as cold spray and wire arc additive manufacturing

Methodology Applied
Scientific EffectWire arc additive manufacturing: Welding

Implementation Method 3

Natural or forced convection can then carry the heat away

Methodology Applied
Scientific EffectNatural convection: Convection

Implementation Method 4

Natural or forced convection can then carry the heat away

Methodology Applied
Scientific EffectForced convection: Forced Convection

Data Source

PatentEP3621183B1Electric machine cooling features
Publication Date: 2021.08.18 HAMILTON SUNDSTRAND CORP
  • EP3621183B1 patent drawingFigure 1
  • EP3621183B1 patent drawingFigure 2~3
  • EP3621183B1 patent drawingFigure 4~5

AI summary

Disclosed is a stator having: a first member (210) having a first plurality of axially opposing ends including a first front end (220) and a first back end (230) mutually spaced along a first stator center axis (240), a first outer diameter (OD) side (250) and a first inner diameter (ID) side (260), wherein first member comprises laminated steel; a plurality of cooling features (280) disposed directly against the first member, wherein the plurality of cooling features spans between the first plurality of axially opposing ends of the first member, and wherein: the stator comprises a base layer (270) disposed directly against the first member, between the first member and the cooling features, thereby reducing an interface contact resistance between the first member and the plurality of cooling features.