Offset Fin Heat Exchanger for Electric Motor Cooling

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Solution Overview

Problem

Existing electric motor cooling systems face inefficiencies in heat removal due to the formation of thick boundary layers in cooling air passages, which reduce heat transfer efficiency as loads and power generation increase.

Innovation Solution

A stator assembly with a heat exchanger featuring offset fins that disrupt airflow and reduce boundary layer formation, enhancing heat transfer by creating thinner boundary layers and increasing contact areas between air and fins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If traditional aligned cooling fins are used in the stator, then the structure is simple and easy to manufacture, but thick boundary layers form in the cooling air passages which reduce heat transfer efficiency

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidfins structure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by offsetting the fins circumferentially relative to adjacent plates, creating an asymmetric fin configuration that disrupts boundary layer formation. This asymmetric arrangement prevents the parallel aligned structure of traditional fins, thereby reducing boundary layer thickness and improving heat transfer efficiency while maintaining manufacturing feasibility through standardized plate components with offset patterns.

Inventive Principle:
Principle #4Asymmetry

2Temperature

If cooling fins are offset circumferentially to disrupt airflow and reduce boundary layers, then heat transfer efficiency improves, but the manufacturing complexity increases

Engineering Contradiction:
Improveheat removal capacityVSAvoidfins alignment precision
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The patent segments the stator into multiple discrete plates, each with fins that can be offset circumferentially. This segmentation allows the offset configuration to be achieved through modular assembly rather than requiring complex monolithic fin structures. Each plate can be manufactured independently with standard offset patterns, simplifying the overall manufacturing process while achieving the desired airflow disruption and heat transfer enhancement.

Inventive Principle:
Principle #1Segmentation

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 significantly improves heat removal capacity by disrupting airflow and minimizing boundary layers, leading to more efficient heat transfer and cooling performance.

Implementation Method 1

Existing electric motor cooling systems face inefficiencies in heat removal due to the formation of thick boundary layers in cooling air passages

Methodology Applied
Scientific EffectBoundary layer: Boundary Layer

Implementation Method 2

Heat generated by operation is controlled by directing air flow over and through a plurality of cooling fins disposed on an exterior surface of the stator

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2058926B1Enhanced motor cooling system
Publication Date: 2016.10.05 HAMILTON SUNDSTRAND CORP
  • EP2058926B1 patent drawingFigure 1
  • EP2058926B1 patent drawingFigure 2
  • EP2058926B1 patent drawingFigure 3

AI summary

A core assembly (16) for an electric motor includes a heat exchanger comprising a plurality of fins (26). The fins define a plurality of cooling air passages (36) that include offset fins that disrupt cooling air flow to reduce the formation of boundary layers and improve heat transfer capacity.