Segmented Stator Cooling Layout for High-Power Electric Machines

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing electric motors for motor vehicle drive trains face challenges in achieving high power density while ensuring effective cooling and cost-effective manufacturing and installation.

Innovation Solution

The electric machine design includes a rotor and stator with separate hydraulic chambers for the stator windings, connected by a hydraulic connecting element that guides electrical conductors and allows for efficient cooling with hydraulic fluid, while also providing electrical insulation and ease of installation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If hydraulic fluid flows directly around the windings to increase power density, then cooling performance is improved, but manufacturing complexity and installation difficulty increase

Engineering Contradiction:
Improvepower densityVSAvoidcooling system complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The stator is divided into multiple independent stator bodies, each with its own hydraulic chamber. This segmentation allows each chamber to be manufactured and cooled independently, reducing overall system complexity while maintaining direct cooling of windings for high power density.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hydraulic connecting element serves multiple functions simultaneously: it connects hydraulic chambers for cooling fluid circulation, provides electrical insulation for conductors passing through, and structurally joins stator bodies. This multi-functionality reduces the number of separate components needed.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Temperature

If separate cooling channels are incorporated into the stator core and slots, then cooling efficiency is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling channel precision
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

Instead of incorporating complex cooling channels into the stator core and slots as a single integrated structure, the design segments the cooling system into separate hydraulic chambers. Each chamber can be manufactured with standard precision tolerances and then assembled, avoiding the need for high-precision integrated cooling channels.

Inventive Principle:
Principle #1Segmentation

3Temperature

If the stator is designed with multiple spaced-apart stator bodies, then cooling access to windings is improved, but device complexity increases

Engineering Contradiction:
Improvewindings cooling accessVSAvoidstator structure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The hydraulic connecting element performs multiple functions: it connects the hydraulic chambers of spaced-apart stator bodies for cooling fluid circulation, provides electrical insulation for conductors, and serves as a structural joining element. This multi-functionality offsets the increased structural complexity by consolidating multiple functions into a single component.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The hydraulic connecting element acts as an intermediary component that enables the spaced-apart stator body design. It mediates between the separated stator bodies, providing both hydraulic connection for cooling and electrical insulation, thus enabling the cooling advantage without proportionally increasing overall system complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If electrical conductors are arranged within hydraulic connecting elements, then electrical insulation is improved, but installation complexity increases

Engineering Contradiction:
Improveelectrical insulationVSAvoidinstallation ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The hydraulic connecting element is designed to perform multiple functions simultaneously: providing hydraulic connection between chambers, providing electrical insulation for conductors, and serving as a structural component. By consolidating these functions into a single pre-designed element, the installation process is actually simplified despite the added insulation capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enhances power density through optimized cooling and electromagnetic design, reduces manufacturing and installation costs, and ensures efficient heat dissipation, making it suitable for high-performance electric vehicle drive trains.

Implementation Method 1

the first stator winding is arranged within a first hydraulic chamber and the second stator body has a second stator winding, wherein the first stator winding is arranged within a first hydraulic chamber and the second stator winding is arranged within a second hydraulic chamber, within which the respective stator windings can each be contacted by a hydraulic fluid

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the electrical machine comprises a hydraulic connecting element which hydraulically connects the first hydraulic chamber to the second hydraulic chamber

Methodology Applied
Scientific EffectFluid flow: Convection

Data Source

PatentEP4320712B1Electric machine
Publication Date: 2025.06.11 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP4320712B1 patent drawingFigure 1
  • EP4320712B1 patent drawingFigure 2
  • EP4320712B1 patent drawingFigure 3

AI summary

The invention relates to an electric machine (1), in particular for an electric drive train in a motor vehicle, comprising a rotor (3) that is rotatably mounted relative to a stator (2), the rotor (3) having a rotor shaft (30) with at least one first rotor member (31) which is non-slidably arranged on the rotor shaft (30) for conjoint rotation therewith, the stator (2) having a first stator member (21) and a second stator member (22) which are spaced apart from one another; the first stator member (21) has a first stator winding (41), and the second stator member (22) has a second stator winding (42), the first stator winding (41) being arranged within a first hydraulic chamber (51), and the second stator winding (42) being arranged within a second hydraulic chamber (52), at least part of the stator windings (41, 42) being able to come into contact with a hydraulic fluid (5) in the hydraulic chambers; the electric machine (1) further comprises a hydraulic connection element (6) which hydraulically connects the first hydraulic chamber (51) to the second hydraulic chamber (52); at least one electric conductor (7) of the first stator winding (41) and/or of the second stator winding (42) is arranged within the hydraulic connection element (6).