Electric Motor Rotor Cooling via Radial and Axial Fluid Channels
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Solution Overview
Problem
Conventional cooling methods for electric motor rotors are not effective in efficiently removing heat, which can lead to damage from high temperatures and limit power density in smaller motor designs.
Innovation Solution
The proposed solution involves a rotor design with radially oriented cavities and fluid channels that connect to a shaft passageway, allowing fluid to flow axially and radially to effectively cool the rotor, enhancing heat removal through a serpentine pathway and multiple fluid exits for uniform cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods (convective air or oil circulation, heat pipes, simple cooling holes) are used, then the rotor can be cooled, but the cooling effectiveness is insufficient to adequately remove heat and protect magnets from damage
Solution Approach 1:
The rotor cooling system is segmented into multiple independent flow passages (first radial flow passage, second radial flow passage, axial flow passage) that can be designed and optimized separately. Each passage serves a specific cooling function, allowing for targeted thermal management of different rotor regions while maintaining overall cooling effectiveness.
Solution Approach 2:
The cooling system transitions from simple radial cooling holes to a three-dimensional network of flow passages including radial passages extending from the shaft and an axial passage connecting them. This multi-dimensional arrangement increases the cooling surface area and improves heat removal efficiency by utilizing both radial and axial flow directions.
2Power
If the motor size is reduced to achieve higher power density, then more power can be obtained from a smaller motor, but heat removal becomes more difficult and magnets are more susceptible to thermal damage
Solution Approach 1:
By introducing axial flow passages that connect radial flow passages, the system creates a three-dimensional cooling network that maximizes heat removal within the limited space of a compact motor. This multi-directional approach increases the effective cooling surface area without proportionally increasing the motor volume.
Solution Approach 2:
The cooling system provides localized cooling zones with flow passages positioned to cool specific high-heat-generation areas in the rotor, such as regions near the magnets. This targeted approach ensures efficient heat removal from critical components while maintaining compact overall dimensions.
3Temperature
If cooling flow passages are added to improve cooling effectiveness, then heat removal improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The rotor shaft serves multiple functions: it supports the rotor mechanically and simultaneously houses the cooling flow passages. This integration reduces the need for separate cooling components, simplifying the overall structure while maintaining effective cooling. The shaft becomes a multi-functional element combining structural and thermal management roles.
Solution Approach 2:
The cooling flow passages are merged with the rotor shaft structure, eliminating the need for separate cooling housings or external cooling mechanisms. The radial and axial passages are integrated into the shaft itself, reducing part count and assembly complexity while achieving superior cooling performance.
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 method provides efficient and cost-effective cooling of electric motor rotors, effectively managing heat and increasing power density by ensuring consistent fluid flow and heat dissipation, even at higher motor speeds.
Implementation Method 1
The fluid channel extends in a generally axial direction and is fluidically connecting the first radially oriented cavity to the second radially oriented cavity
Implementation Method 2
Heat is generated in the rotor due to the changing magnetic fields, which are present in the rotor causing the temperature to rise in the rotor. It is desirable to cool the rotor to protect the magnets or electromagnets from damage
Data Source
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AI summary
An electric motor coupled to a driven device of a vehicle. The electric motor 16 includes a rotor 26 and a shaft 24 coupled to the rotor 26. The rotor 26 has at least one radially oriented cavity 32, 34 and at least one fluid channel 36. The fluid channel 36 extends in a generally axial direction 38. The fluid channel 36 is fluidly connected to the at least one radially oriented cavity 32, 34. The shaft 24 has a fluid passageway 30 therein. The at least one radially oriented cavity 32, 34 has a fluid connection to the fluid passageway 30 of the shaft 24. The at least one radially oriented cavity 32, 34 leads to a radial exit 40, 42 from the rotor 26 for a flow of fluid 22 therefrom.