Aircraft Electric Drive Cooling Using Rotor Blades as Heat Sinks
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Solution Overview
Problem
Existing electric propulsion systems for aircraft face challenges in achieving high power-to-weight ratio, reliability, and fail-safety due to temperature-induced demagnetization of permanent magnets, which is exacerbated by complex and heavy cooling systems, especially in varying aircraft operational conditions.
Innovation Solution
The electric drive system incorporates rotor blades as thermally conductive heat sinks, directly coupled with the rotor shaft and stator vanes, utilizing airflow for efficient cooling, reducing system complexity and weight, and maintaining efficiency even under high load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If permanent magnets are used in high power electric machines, then efficiency increases, but temperature-induced demagnetization occurs reducing reliability
Solution Approach 1:
A thermal management system with heat sinks and thermally conductive material is introduced as an intermediary between the permanent magnets and the environment. This mediator transfers heat away from the magnets, preventing demagnetization while preserving the high efficiency benefits of permanent magnet usage.
Solution Approach 2:
The patent replaces liquid cooling systems with a passive thermal management approach using heat sinks and thermal conduction. This substitution eliminates complex pumps, hoses, and liquid coolant systems while achieving effective heat removal, thereby improving reliability without sacrificing efficiency.
2Temperature
If liquid cooling systems are implemented, then cooling performance improves, but system complexity and weight increase
Solution Approach 1:
The patent extracts the active cooling components (pumps, hoses, liquid coolant) from the thermal management system and replaces them with passive heat sinks. This extraction simplifies the system architecture while maintaining effective cooling performance through direct thermal conduction and convection.
Solution Approach 2:
The thermal management system operates autonomously using natural convection and radiation from the heat sinks. The system self-regulates temperature without requiring external control systems, sensors, or active components, thereby reducing complexity while maintaining effective cooling.
3Temperature
If cooling air flow is directed to the air gap, then magnet cooling is achieved, but system mass and complexity increase
Solution Approach 1:
The rotor blades serve dual functions: generating thrust and acting as heat sinks for magnet cooling. By making the thrust-generating components also responsible for thermal management, the system avoids adding separate cooling infrastructure, thereby reducing overall system mass while achieving effective magnet cooling.
4Device complexity
If natural convection around magnets is relied upon, then system simplicity is maintained, but power output must be limited
Solution Approach 1:
The patent extends the thermal management approach by attaching heat sinks to the rotor blades, utilizing the blade surface area as an additional heat dissipation dimension. This dimensional extension allows higher power outputs by providing sufficient cooling capacity without complicating the system architecture.
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 solution provides a reliable and efficient cooling system that maintains the power-to-weight ratio similar to non-cooled systems, ensuring long-term reliability and high power density, while being cost-effective and fail-safe across different aircraft operations.
Implementation Method 1
the magnets of the rotor are in good thermal contact with a shaft and the shaft is in good thermal contact with the rotor blades attached thereto
Implementation Method 2
the rotor blades of the aircraft, which are always cooled by incoming air during operation of the propulsion system
Implementation Method 3
the use of the rotor blades of the propulsion system as heat sinks for the magnets of the rotor of the electric machine
Data Source
AI summary
An electric drive with a fan for an aircraft, wherein the electric drive comprises an electric machine, in particular a permanently excited electric machine, with a stator and a rotor, and the propeller comprises a shaft and rotor blades, wherein the rotor blades are attached to the shaft, the rotor comprises a laminated core and magnets, wherein the laminated core forms an annular arrangement around the shaft, and the rotor blades, the shaft, the laminated core and the magnets are connected in a thermally conductive manner so that the rotor blades form a heat sink for the magnets.