Permanent Magnet Rotor Cooling Channels for Lightweight Heat Dissipation

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Solution Overview

Problem

Existing solutions for heat dissipation in aircraft engine electrical machines are bulky, heavy, and unreliable, failing to meet the compactness, mass, and reliability requirements of aeronautical applications.

Innovation Solution

Integrating cooling galleries within the permanent magnets of electrical machines to manage thermal dissipation, utilizing channels with turbulent flow and additive manufacturing for optimal thermal management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If natural convection with finned heat sink is used for heat dissipation, then heat dissipation is improved, but the device becomes bulky and heavy

Engineering Contradiction:

Improveheat dissipationVSAvoidmass

Core Design Contradiction:

TemperatureVSWeight of stationary object

Solution Approach 1:

The cooling channels are integrated directly into the permanent magnet structure, merging the magnetic circuit and thermal management functions into a single component. This eliminates the need for separate heat sinks or cooling systems, thereby reducing overall mass while maintaining effective heat dissipation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Cooling channels are specifically positioned within the permanent magnet regions that generate the most heat during transient operations. This localized cooling approach targets the critical thermal zones without requiring bulk cooling systems, optimizing heat dissipation efficiency while minimizing added mass.

Inventive Principle:

Principle #3Local quality

2Temperature

If forced convection with fan is used for heat dissipation, then heat dissipation is improved, but the device becomes bulky and reliability decreases

Engineering Contradiction:

Improveheat dissipationVSAvoidreliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The rotating rotor with integrated cooling channels creates self-generated airflow through its rotation, eliminating the need for external fans or pumps. This self-service cooling mechanism reduces the number of moving parts and potential failure points, thereby improving reliability while maintaining effective heat dissipation during operation.

Inventive Principle:

Principle #25Self-service

3Temperature

If forced cooling with circulating liquid is used for heat dissipation, then heat dissipation is improved, but the device becomes bulky, heavy, and maintenance-intensive

Engineering Contradiction:

Improveheat dissipationVSAvoidsystem complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The system uses gas-phase cooling through channels in the rotating rotor, eliminating the need for liquid cooling systems, heat exchangers, pumps, and associated sealing mechanisms. This pneumatic approach simplifies the overall system architecture, reduces mass, and eliminates maintenance-intensive components while providing effective thermal management.

Inventive Principle:

Principle #29Pneumatics and hydraulics

4Temperature

If electrical machine elements are oversized for heat dissipation, then thermal resistance is improved, but mass and size increase

Engineering Contradiction:

Improvethermal resistanceVSAvoidmass

Core Design Contradiction:

TemperatureVSWeight of moving object

Solution Approach 1:

The cooling channels are embedded within the permanent magnet structure itself, merging the magnetic circuit with the thermal management system. This integration allows the permanent magnets to perform dual functions: generating the magnetic field and dissipating heat, thereby improving thermal resistance without increasing the overall mass of the electrical machine.

Inventive Principle:

Principle #5Merging (Combining)

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 electromagnetic performance, reduces overall mass, and maintains magnetic induction characteristics across a wider temperature range without additional systems, improving mechanical torque and reliability.

Implementation Method 1

a channel allowing the circulation of a fluid... Integrating cooling galleries within the permanent magnets of electrical machines to manage thermal dissipation

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

the channel has a profile configured so that a fluid propagating inside the channel exhibits turbulent flow

Methodology Applied

Scientific EffectTurbulence: Turbulence

Data Source

PatentEP3711142B1Electrical machine of a turbomachine comprising a rotor cooled by a cooling channel

Publication Date: 2026.01.07 SAFRAN HELICOPTER ENGINES

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AI summary

The invention relates to an electrical machine comprising a stator (1) and a rotor (2) designed to be rotated in relation to each other, said rotor (2) or said stator comprising a plurality of permanent magnets (5), at least one permanent magnet comprising at least one fluid-propagation channel (10) extending longitudinally inside the permanent magnet, the propagation channel comprising a fluid inlet and a fluid outlet, the fluid inlet being bell-mouthed and oriented in a preferential direction of rotation of the permanent magnet.