Insulating Ceramic Cooling Cap for Stator Winding Heat Dissipation
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Solution Overview
Problem
Existing cooling solutions for electric machine stators in motor vehicles, such as liquid cooling and casting compounds, often restrict heat dissipation to outer regions and can lead to thermal insulation of inner winding conductors, limiting the effectiveness of cooling and potentially causing overheating.
Innovation Solution
A cooling cap formed from highly thermally conductive, electrically insulating materials like technical ceramic or aluminum oxide is placed onto the winding head, providing efficient passive cooling through convection and allowing for heat dissipation from both accessible and inaccessible regions without the need for casting compounds, thus preventing thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If casting compound is used to encapsulate winding heads for electrical insulation, then electrical insulation is improved, but thermal conductivity deteriorates causing thermal insulation of inner winding conductors
Solution Approach 1:
The invention divides the cooling system into two functional parts: a casting compound layer for electrical insulation and a separate cooling cap for thermal management. The cooling cap is segmented into an outer cooling cap portion and an inner cooling insert that fits into the casting compound, allowing each component to perform its specialized function without compromising the other.
Solution Approach 2:
The inner cooling insert acts as an intermediary element between the winding heads and the outer cooling cap. It provides a thermally conductive pathway through the electrically insulating casting compound, enabling heat to be extracted from inner winding conductors that would otherwise be thermally isolated by the casting material.
2Temperature
If liquid cooling means with cooling ducts in end shields is used, then cooling of electric machine is improved, but cooling effectiveness deteriorates due to restricted heat dissipation to outer regions only
Solution Approach 1:
The invention merges multiple cooling functions into a single integrated cooling cap assembly. The cooling cap combines convective cooling surfaces, conductive heat transfer paths through the cooling insert, and radiative cooling capabilities into one compact component that can be mounted directly on the winding heads, eliminating the need for separate liquid cooling ducts in end shields.
Solution Approach 2:
The cooling cap is designed to utilize ambient air and natural convection currents for cooling, requiring no external liquid cooling system. The structure allows air to flow through and around the cooling cap, creating self-sustaining convective currents that dissipate heat without requiring pumps, ducts, or complex fluid distribution systems.
3Temperature
If cooling cap is placed onto winding head for heat dissipation, then heat dissipation is improved, but electrical insulation deteriorates without proper insulating material
Solution Approach 1:
The invention applies different material properties to different regions of the cooling system. The casting compound provides electrical insulation where needed (around the winding heads), while the cooling cap and insert provide thermal conduction where needed (in contact with winding heads). This localized application of material properties allows both electrical insulation and heat dissipation to function simultaneously.
Solution Approach 2:
The cooling system uses composite construction combining electrically insulating materials (casting compound, ceramic coating) with thermally conductive materials (cooling cap, cooling insert). This composite structure allows the system to simultaneously achieve electrical insulation and thermal management functions that would be contradictory in a single-material system.
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 cooling cap effectively dissipates waste heat from the winding head to the surroundings, enhancing cooling efficiency while maintaining electrical insulation and avoiding the complexity of casting processes, thereby preventing overheating and improving the performance and reliability of electric machine stators.
Implementation Method 1
providing efficient passive cooling through convection
Implementation Method 2
The cooling cap is formed at least in regions from an electric insulation material... formed from highly thermally conductive, electrically insulating materials
Data Source
AI summary
A cooling cap for a stator of an electrical machine of a motor vehicle is provided. The cooling cap can be fitted onto an end winding of electrical windings of the stator which project beyond an axial end of a laminated core of the stator and which cooling cap is designed as a heat sink for cooling the end winding, wherein the cooling cap is formed, at least in regions, from an electrical insulating material. A stator and a motor vehicle including the cooling cap are also provided.