Coil Head Cooling Channel Layout Without Larger Machine Diameter

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Solution Overview

Problem

Conventional cooling systems for electrical machines are inefficient, particularly in cooling the coil heads, leading to increased machine diameter, mass, and maintenance costs, while existing solutions require complex manufacturing and channel passages that do not optimize longitudinal cooling.

Innovation Solution

The implementation of a cooling system where the coil heads are coated with a thermal conductive material and feature a longitudinal cooling channel between the outer casing and an annular plate, allowing efficient heat transfer without increasing the machine's diameter, using a metallic annular plate with projections or ribs for enhanced heat exchange and a movable design for reduced fatigue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a cooling circuit is implemented in the outer jacket, then the stator is cooled well, but the coil heads are not cooled efficiently and the machine diameter increases

Engineering Contradiction:
Improvestator cooling efficiencyVSAvoidmachine diameter
Core Design Contradiction:
TemperatureVSLength of stationary object

Solution Approach 1:

The cooling system is segmented into two independent parts: a radial cooling circuit in the outer jacket for stator cooling, and a longitudinal cooling channel between the flange and coil end coating material for coil head cooling. This segmentation allows each cooling path to be optimized independently, enabling efficient coil head cooling without increasing machine diameter.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces a new cooling dimension by creating a longitudinal cooling channel in the axial direction between the flange and coil end coating material. This adds a longitudinal cooling pathway complementary to the existing radial cooling, enabling direct cooling of coil heads without expanding the radial dimension of the machine.

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

2Temperature

If thermally conductive resin is used to cool coil heads, then cooling effectiveness improves, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvecoil head cooling efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The invention extracts the cooling function from the complex thermally conductive resin system and implements it through a simple longitudinal cooling channel structure. By removing the need for specialized thermally conductive coating materials and complex application processes, the solution achieves effective coil head cooling through conventional manufacturing methods.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The longitudinal cooling channel acts as an intermediary structure between the cooling fluid and the coil heads. Instead of relying on complex thermally conductive materials to transfer heat, the channel provides a direct pathway for cooling fluid to remove heat from the coil heads, simplifying the thermal management system.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If cooling channels are arranged in the casing, then coil heads are cooled, but the machine diameter increases and manufacturing is complicated

Engineering Contradiction:
Improvecoil head coolingVSAvoidmachine diameter
Core Design Contradiction:
TemperatureVSLength of stationary object

Solution Approach 1:

The invention transitions from radial cooling channels in the casing to a longitudinal cooling channel in the axial direction. By utilizing the space between the flange and coil end coating material in the axial dimension, the solution achieves coil head cooling without expanding the radial dimension of the machine.

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

Solution Approach 2:

The longitudinal cooling channel is specifically positioned between the flange and coil end coating material to target the coil heads directly. This localized cooling approach concentrates cooling effectiveness where it is most needed without requiring extensive modifications to the overall machine 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

This solution effectively cools the coil heads longitudinally, reducing the machine's thickness and diameter, improving performance and lifespan while minimizing maintenance, and is suitable for compact applications like vehicles.

Implementation Method 1

a cooling channel for circulation of a cooling fluid, said cooling channel being formed between said outer casing of said electrical machine and an annular plate fixed to a longitudinal end of said coating material of said coil heads

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 2

the coil heads are coated with a coating material... efficient heat transfer without increasing the machine's diameter

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4307538A1Electric machine with a cooling channel between a flange and the coil end coating material
Publication Date: 2024.01.17 IFP ENERGIES NOUVELLES
  • EP4307538A1 patent drawingFigure 1
  • EP4307538A1 patent drawingFigure 2~3
  • EP4307538A1 patent drawingFigure 4~5

AI summary

The present invention relates to an electrical machine (1) comprising a stator (3), a rotor (2), a housing (4), and two end caps (5). The stator comprises a stator body and coils (6), the ends of which form coil heads (7) outside the stator body. According to the invention, the coil heads (7) are embedded in an encapsulating material (8). Furthermore, at each end of the electrical machine (1), a cooling channel (10) is formed between the outer casing of the electrical machine (1) and an annular plate fixed (9) to the encapsulating material (8).