Motor Cooling Flow Path Structure for Uniform Axial Coolant Distribution

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Solution Overview

Problem

Existing cooling structures for motors fail to effectively equalize the flow rate and/or flow velocity of coolant in the axial direction, leading to uneven cooling and potential local overheating.

Innovation Solution

A coolant flow path design featuring an expansion portion with increasing axial width in the circumferential direction, branching into multiple branch flow paths, and incorporating projections to temporarily stagnate coolant, thereby equalizing flow resistance and velocity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If coolant flows directly from supply port to branch portion without expansion portion, then flow path is simple and short, but flow rate and velocity are uneven in axial direction

Engineering Contradiction:
Improveflow path structureVSAvoidflow rate uniformity
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The expansion portion extends in the circumferential direction (perpendicular to axial direction) while increasing axial width, creating a two-dimensional expansion that allows coolant to equalize flow in axial direction before entering branch portion, thus improving flow uniformity without significantly increasing path length

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

Solution Approach 2:

The expansion portion with projections creates preliminary flow resistance equalization before coolant reaches the branch portion, ensuring that flow rate and velocity are already equalized in axial direction before distribution to multiple branches

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If first projection blocks part of coolant flow, then flow resistance equalization improves, but local flow stagnation may occur

Engineering Contradiction:
Improveflow resistance equalizationVSAvoidcoolant flow efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The first projection is positioned at a specific location within the expansion portion to create localized flow resistance that equalizes axial flow distribution without completely blocking flow, allowing differential flow control at different axial positions

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The projection extends in the axial direction to narrow radial width, creating flow resistance in radial direction that indirectly equalizes axial flow distribution by forcing coolant to redistribute across axial positions

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

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 design ensures uniform coolant distribution, preventing local overheating and enhancing overall cooling efficiency by equalizing flow rate and velocity across the axial direction.

Implementation Method 1

a part of the coolant supplied from the supply port into the expansion portion is blocked by the first projection and thus temporarily stays within the expansion portion. This temporal stay of the coolant within the expansion portion equalizes flow resistance of the coolant in the axial direction

Methodology Applied
Scientific EffectFlow resistance equalization:

Implementation Method 2

a width of the expansion portion in an axial direction increases along the circumferential direction... equalizes the flow rate and/or flow velocity of the coolant in the axial direction which is going to flow downstream beyond the first projection

Methodology Applied
Scientific EffectFluid flow equalization:

Data Source

PatentEP4618379A1Cooling structure
Publication Date: 2025.09.17 TOYOTA JIDOSHA KK
  • EP4618379A1 patent drawingFigure 1
  • EP4618379A1 patent drawingFigure 2
  • EP4618379A1 patent drawingFigure 3

AI summary

A cooling structure for a motor extending in an axial direction may include a coolant flow path configured to allow coolant to flow in a circumferential direction of the motor and a supply port (21S) through which the coolant is supplied to the coolant flow path. The coolant flow path may include an expansion portion (31S) extending from the supply port in the circumferential direction, wherein a width of the expansion portion in the axial direction increases along the circumferential direction; and a branch portion (33S) extending from the expansion portion in the circumferential direction and branching into a plurality of branch flow paths. The expansion portion may include a first projection (35aS) extending in the axial direction and narrowing a width of the coolant flow path in a radial direction of the motor.