Rotor Air Cooling Structure for Low-Complexity Thermal Management
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Solution Overview
Problem
In electric machines, such as those in electric or hybrid vehicles, the thermal limitations of rotor magnets and stator windings lead to performance reduction and potential failure due to overheating, necessitating effective cooling solutions that are often complex and costly when using liquid mediums like water or oil.
Innovation Solution
A rotor air cooling system comprising an outer and inner housing with a main rotor body and stator, utilizing axial air flow through cavities and a water jacket for cooling, with a heat exchanger for heat dissipation, allowing for recirculation of cooled air to efficiently manage heat without the complexity and expense of liquid cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid cooling medium (water or oil) is used to cool rotor magnets and stator windings, then cooling effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies pneumatic cooling by using air as the cooling medium instead of liquid cooling. Air is circulated through channels in the rotor and stator components, carrying away heat through convection. This eliminates the need for liquid cooling systems including pumps, radiators, and complex fluid management infrastructure, thereby reducing device complexity while maintaining cooling effectiveness.
Solution Approach 2:
The patent replaces the mechanical liquid cooling system with a simpler air-based cooling mechanism. Instead of using liquid circulation systems with pumps and heat exchangers, the invention uses air flow through structured channels and cavities in the rotor and stator, substituting a complex mechanical system with a simpler thermal convection-based system.
2Loss of energy
If liquid cooling medium is used, then heat dissipation capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses air as the cooling medium, which is freely available and eliminates the need for expensive liquid cooling infrastructure. The air cooling system with its simpler structure requires fewer manufactured components, reducing manufacturing costs while maintaining adequate heat dissipation capability through optimized air flow paths and thermal management geometry.
Solution Approach 2:
The patent changes the cooling medium from liquid to gas (air), fundamentally altering the thermal management approach. This parameter change allows for simpler manufacturing processes, reduced material costs, and elimination of complex cooling system components, thereby reducing overall manufacturing cost while maintaining heat dissipation effectiveness through proper air flow design.
3Device complexity
If air cooling is used instead of liquid cooling, then device complexity is reduced, but cooling effectiveness may deteriorate
Solution Approach 1:
The patent segments the air cooling system into multiple dedicated cooling zones and channels within the rotor and stator structures. By creating separate cooling paths for different components (rotor magnets, stator windings, core), the system ensures adequate cooling effectiveness for each thermal zone while maintaining overall system simplicity. This segmentation allows optimized thermal management without requiring complex liquid cooling infrastructure.
Solution Approach 2:
The patent utilizes three-dimensional cooling channels and cavities integrated into the rotor and stator structures, creating efficient heat transfer paths through the component geometry. By designing cooling passages that extend through the depth and structure of the components, the air cooling system achieves effective heat removal despite the lower heat capacity of air compared to liquid, maintaining cooling effectiveness while preserving system simplicity.
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 system provides an efficient, cost-effective, and less complex cooling solution that effectively manages heat in electric machines, enhancing performance and reliability by using air instead of liquids, thereby preventing overheating and thermal fatigue.
Implementation Method 1
cooling air axially enters the main rotor body in an inlet end, passes through cavities of the main rotor body
Implementation Method 2
a heat exchanger for dissipating heat from the cooling air exiting the main rotor body
Implementation Method 3
a water jacket arranged between the inner housing and the outer housing
Data Source
AI summary
A rotor air cooling system including an outer housing and an inner housing configured to be inserted into the outer housing, the inner housing including an open backend. The system further includes a stator attached to an interior side of the inner housing, a main rotor body included in the inner housing, the main rotor body being arranged around a rotor shaft arranged to extend through the inner housing and the outer housing, wherein cooling air axially enters the main rotor body in an inlet end, passes through cavities of the main rotor body, and exits the main rotor body in an outlet end, and a water jacket arranged between the inner housing and the outer housing. Moreover, the system includes a heat exchanger for dissipating heat from the cooling air exiting the main rotor body.