Electric Motor Rotor Air Cooling Cavities
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Solution Overview
Problem
Existing electric motor rotor systems face challenges in efficiently cooling the rotor while minimizing friction losses, which affects motor performance and the driving range of electric vehicles.
Innovation Solution
A rotor system with an air circulation cooling system that includes a rotor core with internal cavities and end rings with entry and exit openings, allowing air to circulate through the cavities and around the rotor, thereby inhibiting liquid from entering the air gap and reducing friction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling liquid is supplied around the rotor, then cooling effect is improved, but friction loss increases due to spin losses
Solution Approach 1:
Air is introduced as an intermediary cooling medium between the rotor and the external environment. The air circulates through internal cavities within the rotor core, absorbing heat internally without requiring external liquid cooling that would contact the rotating rotor and cause friction losses.
Solution Approach 2:
The patent employs pneumatic cooling by circulating air through the rotor's internal cavity system. This replaces hydraulic cooling (liquid) with pneumatic cooling (gas), eliminating the friction and spin losses associated with liquid cooling while maintaining effective heat removal from the rotor.
2Loss of energy
If air circulation cooling is implemented through internal cavities, then friction loss is reduced, but device complexity increases
Solution Approach 1:
The internal cavities serve multiple functions simultaneously: they act as flux barriers for magnetic field management and as cooling channels for thermal management. This multi-functionality reduces the need for separate dedicated cooling structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The cooling cavities are nested within the existing rotor core structure, utilizing the internal space already present for magnetic flux management. This nesting approach allows the cooling system to be integrated into the existing rotor design without requiring additional external components or significantly increasing overall structural complexity.
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 air circulation cooling system effectively manages thermal issues within the rotor, enhancing motor performance and longevity while maintaining low friction losses, thus improving the driving range of electric vehicles.
Implementation Method 1
The rotor core operates to circulate an air flow through the cavity by rotation of the rotor core
Implementation Method 2
Removing the heat from the motor to avoid high operating temperatures is desirable
Data Source
AI summary
A rotor for an electric machine includes an air circulation cooling system. The rotor includes a rotor core having cavities internal to the rotor core. The rotor core extends longitudinally between two ends. The cavities are defined by the rotor core. The cavities extend through the rotor core and open through at least one of the ends. The rotor core operates to circulate air through the cavities by rotation of the rotor core.