Electric Machine Stator Cooling With Insulated Hydraulic Chambers
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Solution Overview
Problem
Existing electric machines for motor vehicles face challenges in achieving high power density while ensuring effective cooling and cost-effective assembly, particularly in hybrid and fully electric drive trains.
Innovation Solution
The electric machine incorporates a rotor and stator design with hydraulic chambers for stator windings, connected by hydraulic connection elements made of electrically non-conductive material, which facilitate direct contact with coolant for enhanced cooling and provide electrical insulation, while using seals and press fits for chamber separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hydraulic fluid flows directly around the windings to increase power density, then cooling efficiency is improved, but electrical insulation reliability deteriorates
Solution Approach 1:
The patent introduces an electrically insulating layer as an intermediary between the hydraulic fluid and the conductors. This layer allows the hydraulic fluid to flow directly around the windings for efficient cooling while preventing electrical contact between the conductive fluid and the conductors, thus maintaining insulation reliability.
Solution Approach 2:
The patent applies different properties to different parts of the conductor structure. The conductors have an electrically insulating coating on their surface, allowing the bulk conductor to remain conductive for electrical function while the surface provides insulation where it contacts the hydraulic fluid, enabling local differentiation of electrical properties.
2Temperature
If complex cooling structures like separate cooling channels are introduced into the stator, then cooling performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The hydraulic connection elements serve multiple functions simultaneously: they connect hydraulic chambers, provide cooling fluid flow paths, and offer electrical insulation. This multi-functionality eliminates the need for separate dedicated cooling channels, simplifying the overall structure while maintaining effective cooling performance.
Solution Approach 2:
The patent merges the cooling function with the existing hydraulic connection elements that link the hydraulic chambers. By integrating cooling fluid flow through these existing structural components rather than adding separate cooling channels, the design achieves effective cooling while minimizing manufacturing complexity.
3Ease of manufacture
If traditional cooling methods like jacket cooling are used, then manufacturing simplicity is maintained, but cooling efficiency is insufficient for high power density
Solution Approach 1:
The patent employs hydraulic fluid flowing directly around the windings in the hydraulic chambers to achieve superior cooling efficiency. This hydraulic cooling approach, utilizing the existing hydraulic connection elements and fluid system, provides much higher cooling efficiency than traditional jacket cooling while maintaining manufacturing simplicity through the integration with existing hydraulic components.
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 achieves high power density, efficient cooling, and cost-effective assembly, supporting vehicle speeds over 50 km/h with outputs exceeding 30 KW, particularly suitable for hybrid and fully electric vehicles.
Implementation Method 1
the heat transfer takes place directly on the conductors outside the stator laminations in the region of the winding heads into the fluid
Implementation Method 2
hydraulic connection elements made of electrically non-conductive material, which facilitate direct contact with coolant for enhanced cooling and provide electrical insulation
Data Source
AI summary
An electric machine for an electric drive train in a motor vehicle including a rotor that is rotatably mounted relative to a stator, the rotor having a rotor shaft with at least one first rotor member which is non-slidably arranged on the rotor shaft for conjoint rotation therewith, the stator having a first stator member and a second stator member which are spaced apart from one another; the first stator member has a first stator winding, and the second stator member has a second stator winding, the first stator winding being arranged within a first hydraulic chamber, and the second stator winding being arranged within a second hydraulic chamber, at least part of the stator windings being able to come into contact with a hydraulic fluid in the hydraulic chambers. The electric machine further including a hydraulic connection element which hydraulically connects the first hydraulic chamber to the second hydraulic chamber; at least one electric conductor of the first stator winding and/or of the second stator winding is arranged within the hydraulic connection element.