Rotor Pole Separator With Porous Cooling for Winding Heat Transfer

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Solution Overview

Problem

The existing rotor configurations in electric rotating machines, particularly Electrically Excited Synchronous Motors (EESMs), suffer from inefficient heat transfer due to the proximity of rotor windings near the rotor shaft, which limits the cooling efficiency and power density.

Innovation Solution

Incorporating a pole separator with a thermally conductive porous material and a thermally conductive sheath that includes a coolant flow passage, allowing radial distribution of cooling effect over the rotor windings, enhancing heat transfer efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a cooling fluid pipe is arranged in the pole separator close to the upper part of the circumferential space, then the rotor windings in the upper part are cooled, but the rotor windings located in a radial position proximal to the rotor shaft are far from the cooling fluid pipe resulting in poor heat transfer efficiency

Engineering Contradiction:
Improvecooling efficiency of rotor windingsVSAvoidheat transfer efficiency
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The pole separator incorporates a thermally conductive porous material containing coolant flow passages distributed throughout its structure. This porous material enables the coolant to reach and cool rotor windings at all radial positions, including those proximal to the rotor shaft that were previously difficult to cool effectively.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The thermally conductive porous material acts as an intermediary between the coolant and the rotor windings. It facilitates heat transfer from the windings to the coolant by providing extensive thermal conduction pathways while maintaining structural integrity and coolant flow channels.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If rotor windings are wound around pole members extending radially from the rotor shaft, then the motor structure is compact and powerful, but heat dissipation becomes difficult especially for windings near the rotor shaft

Engineering Contradiction:
Improvepower density of motorVSAvoidheat dissipation capability
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The pole separator is designed to perform multiple functions simultaneously: it provides mechanical support to hold rotor windings in place, acts as a thermal conductor to transfer heat from windings, and serves as a coolant distribution system through its porous structure with integrated flow passages.

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

Solution Approach 2:

The thermally conductive porous material is specifically positioned in the pole separator where heat transfer is most needed - in the circumferential spaces between pole members where rotor windings are located. This localized thermal conductivity enhancement targets the specific heat dissipation problem areas without requiring complete redesign of the entire rotor structure.

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

The improved heat transfer configuration efficiently dissipates heat from the rotor windings, increasing the power density of the electric rotating machine by allowing higher electric current without thermal limitations.

Implementation Method 1

at least one of the one or more pole separators includes a structure having a thermally conductive porous material including a coolant flow passage

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The above structure enables efficient heat transfer in the pole separator(s) from the coolant flow passage to the rotor windings

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4614771A1An electric rotating machine with improved heat transfer capacity
Publication Date: 2025.09.10 TOYOTA JIDOSHA KK
  • EP4614771A1 patent drawingFigure 1~2
  • EP4614771A1 patent drawingFigure 3~4A
  • EP4614771A1 patent drawingFigure 4B~5A

AI summary

A rotor (30) of an electric rotating machine (10), comprising: - a rotor shaft (32) having a longitudinal axis (X); - a rotor core (34) surrounding the rotor shaft (32) and having a plurality of pole members (36) arranged circumferentially about the rotor shaft and spaced apart from each other by a circumferential space (38), each pole member (36) extending radially relative to the rotor shaft (32) and away therefrom, each pole member (36) being provided with rotor windings (40) that are wound around the pole member, a pole separator (42) being arranged in each circumferential space (38) so as to keep the rotor windings in place, one or more pole separators (42) including a coolant, characterized in that at least one of the one or more pole separators (42) includes a structure having a thermally conductive porous material (44) including a coolant flow passage.