Stacked Stator Core Cooling Channels for Lower Motor Heat

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Solution Overview

Problem

Electrical machines, such as electric motors, face various losses including resistive, hysteresis, and thermal losses, which can lead to increased resistance and potential damage due to thermal constraints, necessitating effective cooling solutions to manage these losses.

Innovation Solution

A stator stack design featuring stacked laminations with projecting mounting lobes and indentations that form coolant flow channels, allowing an oil-dispersing coolant to flow along the circumference for enhanced cooling, with the dimensions of these channels adjustable based on desired flow rates and thermal constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional stator designs without integrated coolant channels are used, then the structure is simpler and manufacturing is easier, but thermal losses increase and maximum operating temperature rises

Engineering Contradiction:

Improvemaximum operating temperatureVSAvoidstator structure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The stator core is segmented into multiple laminations, each with integrated coolant flow channels formed by indentations in the mounting lobes. This segmentation allows coolant to flow through multiple discrete paths across different laminations, effectively distributing heat removal throughout the stator structure while maintaining a modular design approach

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coolant flow channels are merged directly into the mounting lobes of the stator laminations by forming indentations during manufacturing. This integration combines the structural mounting function with the thermal cooling function into a single component, eliminating the need for separate coolant channels and reducing overall device complexity despite the enhanced cooling capability

Inventive Principle:

Principle #5Merging (Combining)

2Loss of energy

If coolant flow channels are added to reduce thermal losses, then cooling effectiveness improves, but manufacturing complexity increases

Engineering Contradiction:

Improvethermal lossesVSAvoidlamination manufacturing

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The coolant flow channels are formed by creating indentations in the mounting lobes during the lamination manufacturing process itself, before the laminations are assembled into the stator stack. This preliminary action ensures that the cooling channels are already integrated into the structural components, eliminating the need for additional post-assembly machining or drilling operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dimensions and geometry of the coolant flow channels are controlled by adjusting the indentation parameters during manufacturing. By varying the depth, width, and shape of the indentations in the mounting lobes, the channel dimensions can be optimized for specific coolant flow rates and thermal performance requirements, allowing flexible parameter tuning without fundamental design changes

Inventive Principle:

Principle #35Parameter changes

3Reliability

If stacked laminations with coolant channels are used, then cooling efficiency increases, but the device complexity and assembly precision requirements increase

Engineering Contradiction:

Improvethermal management reliabilityVSAvoidlamination indexing precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The mounting lobes are designed with asymmetric features, including non-circular cross-sections and specific geometric profiles, that create inherent mechanical keys andways. This asymmetry ensures that laminations can only be assembled in the correct rotational orientation, automatically achieving the required 90-degree indexing between adjacent laminations and eliminating the need for complex alignment procedures or precision fixtures

Inventive Principle:

Principle #4Asymmetry

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 design effectively reduces the maximum operating temperature of the electric motor drive unit, increasing its reliability and operational lifespan by preventing thermal damage and maintaining optimal stress levels.

Implementation Method 1

an oil-dispersing coolant dispersed to the stator stack may be allowed to pervade each of the mounting lobes of each lamination and flow along the circumference of the stator stack for more effectively cooling the stator stack

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS20230378826A1Stator core of stacked laminations with coolant flow channels

Publication Date: 2023.11.23 RIVIAN HOLDINGS LLC

AI summary

A stator assembly includes a plurality of laminations configured to form a stator stack. Each of the plurality of laminations includes a set of projections disposed along an outer perimeter of the lamination, in which each of the set of projections includes a mounting hole passing therethrough. Each of the plurality of laminations further includes a plurality of indentations each extending into a respective one of the set of projections. The plurality of laminations are configured to form the stator stack in accordance with a predetermined indexing, such that the plurality of indentations define one or more coolant flow channels.