Helical Housing Cooling Path for Rotating Electrical Machines

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Solution Overview

Problem

Rotating electrical machines face cooling performance issues when the refrigerant inlet and outlet are positioned far apart in the circumferential direction of the housing, leading to portions without a refrigerant flow path and inadequate cooling.

Innovation Solution

The design incorporates a refrigerant flow path within the inner housing that includes a first flow path with increasing width and a second flow path with decreasing width, ensuring continuous cooling coverage even when the inlet and outlet are separated by 180 degrees.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the inlet and outlet of the refrigerant are arranged at positions separated from each other in the circumferential direction of the housing, then the arrangement is adapted to drive unit constraints, but a portion without a flow path is generated on the circumferential surface resulting in insufficient cooling

Engineering Contradiction:
Improveadaptability to drive unit arrangementVSAvoidcooling performance
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

The flow path transitions from a two-dimensional circumferential pattern to a three-dimensional helical structure that wraps around the stator, allowing the refrigerant to cover the entire circumferential surface despite separated inlet and outlet positions in the axial direction

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

Solution Approach 2:

The helical flow path uses curved geometry to wrap continuously around the stator, ensuring comprehensive cooling coverage without leaving uncovered portions on the circumferential surface

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Temperature

If the inlet and outlet of the refrigerant are located at substantially the same position in the circumferential direction, then a flow path can cover the entire circumferential surface, but the arrangement is limited by drive unit member constraints

Engineering Contradiction:
Improvecooling performanceVSAvoidadaptability to drive unit arrangement
Core Design Contradiction:
TemperatureVSAdaptability or versatility

Solution Approach 1:

The solution moves the flow path design into the third dimension by creating a helical structure that ascends axially while wrapping circumferentially, enabling flexible inlet/outlet positioning without compromising cooling coverage

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

3Productivity

If a straight flow path connects separated inlet and outlet positions, then the flow path length is reduced, but flow path non-forming portions are generated causing insufficient cooling

Engineering Contradiction:
Improverefrigerant flow efficiencyVSAvoidcooling coverage
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The helical curved path eliminates dead zones and non-forming portions by maintaining continuous contact with the stator surface, ensuring uniform cooling distribution throughout the entire circumferential area

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 configuration effectively prevents the formation of flow path non-forming portions, ensuring that the entire heat generation range is cooled, thereby enhancing the cooling performance of the rotating electrical machine.

Implementation Method 1

a refrigerant flow path 24 allowing a refrigerant 13 to flow

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the refrigerant 13 flows through the refrigerant flow path 24

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4307535B1Rotating electrical machine
Publication Date: 2025.04.23 NISSAN MOTOR CO LTD
  • EP4307535B1 patent drawingFigure 1~2
  • EP4307535B1 patent drawingFigure 3~4
  • EP4307535B1 patent drawingFigure 5~6

AI summary

A rotating electrical machine includes a cylindrical housing having a flow path configured to allow a refrigerant to flow therethrough, an inlet configured to allow the refrigerant to flow into the flow path, and an outlet configured to allow the refrigerant to flow out of the flow path. The flow path being formed so as to spirally surround a circumferential surface of the housing. The flow path includes: a first flow path that is formed along one end surface of the housing and formed such that a width along the circumferential surface increases along a flow direction of the refrigerant from the inlet; and a second flow path that is formed along the other end surface of the housing and formed such that a width along the circumferential surface decreases toward the outlet along the flow direction of the refrigerant.