Rotary Motor Rotor Cooling via Axial Radial Fluid Conduits

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Solution Overview

Problem

High-performance motors face challenges in cooling due to increased stator temperatures, which reduce natural cooling capacity for rotors, leading to overheating, especially in sealed enclosures where air cooling is ineffective, and higher magnetic eddy current heating from simpler magnet structures.

Innovation Solution

A rotary device with a rotor housing featuring axial and radial fluid conduits for coolant flow, combined with tortuous paths and a fluid impeller to ensure efficient heat transfer and minimize pressure losses, allowing for effective cooling of the rotor while maintaining low rotor temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the stator is designed to operate at high temperatures to maximize power density and minimize cost, then manufacturing cost and power density are improved, but the natural cooling capacity for the rotor is reduced leading to rotor overheating

Engineering Contradiction:
Improvemanufacturing costVSAvoid rotor temperature
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The cooling system is segmented into multiple independent components: an impeller for fluid agitation, axial conduits for fluid transport, radial conduits for fluid distribution, and tortuous paths for enhanced heat transfer. This segmentation allows each component to be optimized independently while working together to solve the cooling problem.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling fluid paths transition from simple axial flow to multi-dimensional tortuous paths that wrap around the rotor housing. This dimensional change increases the heat transfer surface area and improves cooling efficiency without increasing the overall motor size.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If simpler magnet structures are used to reduce manufacturing complexity and cost, then ease of manufacture is improved, but magnetic eddy current heating increases leading to rotor overheating

Engineering Contradiction:
Improvemagnet structure complexityVSAvoid rotor temperature
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The cooling system converts the harmful effect of eddy current heating into a beneficial cooling opportunity by providing dedicated cooling paths that specifically target the rotor housing and magnet areas, allowing simpler magnet structures to be used without compromising thermal management.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the rotor is enclosed in a sealed enclosure to protect components, then reliability is improved, but air cooling capability is eliminated leading to reduced heat dissipation

Engineering Contradiction:
Improvecomponent protectionVSAvoid rotor temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The sealed enclosure cooling system uses a liquid coolant delivered by an impeller-driven hydraulic system. The coolant flows through axial and radial conduits and tortuous paths within the rotor housing, providing effective heat removal while maintaining the sealed enclosure for component protection.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 solution enables efficient heat transfer from the rotor to the coolant, maintaining low rotor temperatures and reducing magnetic eddy currents, thus enhancing motor performance and reliability while minimizing manufacturing complexity and costs.

Implementation Method 1

The solution enables efficient heat transfer from the rotor to the coolant

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a fluid impeller to ensure efficient heat transfer and minimize pressure losses

Methodology Applied
Scientific EffectImpeller: Impeller

Data Source

PatentEP2907222B1A rotary device, a motor and a method of cooling a motor
Publication Date: 2022.01.05 INTEGRAL POWERTRAIN LTD
  • EP2907222B1 patent drawingFigure 1
  • EP2907222B1 patent drawingFigure 2A
  • EP2907222B1 patent drawingFigure 2B

AI summary

The invention provides a rotary device, comprising: a stator for receiving or outputting electrical power;a rotor arranged coaxially within the stator and having one or more magnets arranged thereon,the rotor comprising a rotor housing having an inner wall, the magnets being arranged around the housing, and wherein the rotor also comprises an axial fluid conduit for the flow of a coolant between a first end of the rotor and a second distal end of the rotor;the rotor further comprising one or more radial fluid conduits, the radial fluid conduits being fluidly coupled to the axial fluid conduit and arranged in use to receive coolant from or provide coolant to the axial fluid conduit, the inner wall having one or more fluid paths for the flow of coolant, thereby to cool the rotor; and a fluid impeller arranged at the first or distal end of rotor and arranged to rotate with the rotor and impart to and/or maintain rotary movement of or remove from and/or maintain rotary movement of fluid entering or leaving the rotary device.