Rotor Cooling Channels With Fluid Injection for Electric Machines
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Solution Overview
Problem
Electrical machines in electrified vehicles face significant thermal power loss and efficiency reduction due to heat generation, especially under high loads, which can cause permanent magnet demagnetization in synchronous machines at elevated temperatures, necessitating an optimized cooling solution without compromising performance or power density.
Innovation Solution
An electrical machine design featuring a rotor with axial end faces, lateral surfaces, and cooling channels that extend from injection openings, utilizing injection nozzles to spray cooling fluid during rotation, minimizing recirculation and leveraging centrifugal force and Bernoulli effect for efficient fluid flow and distribution, along with integrated sensors for temperature and imbalance monitoring to adjust cooling fluid injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power and high load operation is implemented, then power output is improved, but thermal power loss and heat development increase causing efficiency reduction and potential permanent magnet demagnetization
Solution Approach 1:
The patent employs a hydraulic cooling system where cooling fluid is injected through nozzles into cooling channels within the rotor. This hydraulic approach enables direct cooling of the rotor structure, effectively removing thermal power loss and preventing overheating during high power operation, thus resolving the contradiction between power output and thermal losses
2Temperature
If conventional cooling systems are added, then thermal management is improved, but device complexity and power density are compromised
Solution Approach 1:
The cooling channels are integrated directly into the rotor structure, merging the cooling system with the motor structure. This eliminates the need for separate cooling components and reduces overall system complexity while maintaining effective thermal management during high power operation
3Temperature
If cooling fluid is continuously sprayed, then cooling effectiveness is improved, but fluid usage efficiency decreases due to recirculation and waste
Solution Approach 1:
The injection nozzles are configured to spray cooling fluid dynamically synchronized with rotor rotation. The nozzles are positioned to inject fluid at optimal moments during rotor rotation, ensuring cooling effectiveness while minimizing fluid recirculation and waste through precise timing and directional control
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 ensures reliable, efficient cooling of electrical machines with a simple mechanical structure, reducing thermal losses and maintaining performance by optimizing cooling fluid distribution and usage, thus enhancing the efficiency and power density of electrical machines.
Implementation Method 1
leveraging centrifugal force and Bernoulli effect for efficient fluid flow and distribution
Implementation Method 2
cooling channels each extend into the rotor from an injection opening... spray a fluid into the injection opening of the cooling channels
Implementation Method 3
leveraging centrifugal force and Bernoulli effect for efficient fluid flow and distribution
Data Source
AI summary
Methods and systems are provided for an electrical machine including a shaft configured to rotate about an axis of rotation, a rotor coupled to the shaft and a stator, wherein the rotor includes a first axial end face, a second axial end face, a lateral surface, and at least two cooling channels, wherein the cooling channels each extend into the rotor from an injection opening in the first axial end face, and at least one injection nozzle configured to spray a fluid into the injection opening of the cooling channels when the rotor is rotating.