Reverse-Air-Cycle Cooling for Compact Electric Machines
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Solution Overview
Problem
Existing fluid cooling systems for electric machines are often bulky and complex, making them less desirable for efficient heat management.
Innovation Solution
The proposed solution involves an air-cooled electric machine system that includes a turbine, an electric machine with air passages for cooling, and a compressor, which work together in a reverse air cycle to efficiently extract heat from the electric machine using air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oil cooling systems are used for electric machines, then cooling effectiveness is improved, but system complexity and bulk increase
Solution Approach 1:
The patent applies pneumatic cooling by using air instead of oil as the cooling medium. The system includes a turbine that expands air to produce cold air, which then flows through the electric machine to absorb heat, and a compressor that re-compresses the warmed air. This pneumatic approach eliminates the complexity of oil cooling systems while maintaining effective cooling through the reverse air cycle process.
2Temperature
If oil cooling systems are used for electric machines, then cooling effectiveness is improved, but system weight increases
Solution Approach 1:
The patent replaces heavy oil cooling infrastructure with a lightweight pneumatic system using air as the cooling medium. The reverse air cycle system with turbine and compressor components is significantly lighter than traditional oil cooling systems, reducing overall system weight while maintaining cooling effectiveness through the expansion and compression of air.
3Device complexity
If air cooling is used for electric machines, then system simplicity is improved, but cooling effectiveness may worsen
Solution Approach 1:
The patent employs parameter changes by utilizing the thermodynamic properties of air through expansion and compression. The turbine expands air to dramatically lower its temperature (cooling it to -40°F or lower), and the compressor raises its temperature and pressure. This parameter manipulation enables air to become an effective cooling medium, matching or exceeding oil cooling effectiveness while maintaining system simplicity.
Solution Approach 2:
The system exploits phase transitions and thermodynamic state changes of air. During turbine expansion, air undergoes adiabatic cooling to very low temperatures. During compressor operation, air is heated and pressurized. These reversible phase/state transitions enable the air to efficiently absorb and reject heat, providing effective cooling through a simple pneumatic 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
This system provides a compact, low-weight, and simple cooling solution for electric machines, minimizing internal windage losses and maintaining aircraft engine performance with minimal impact.
Implementation Method 1
expanding and cooling air from the flow of air using a turbine
Implementation Method 2
conveying the flow of air from the turbine through the electric machine to extract heat from the electric machine using the flow of air
Implementation Method 3
drawing the flow of air through the electric machine using an air mover
Data Source
AI summary
Systems and methods for cooling electric machines are provided. A method for cooling an electric machine includes receiving a flow of air, expanding and cooling the air from the flow of air using a turbine, conveying the flow of air from the turbine through the electric machine to extract heat from the electric machine using the flow of air, and drawing the flow of air through the electric machine using an air mover.