Rotor Vane Cooling for Compact Permanent Magnet Machines
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Solution Overview
Problem
Existing electrical machines, particularly in unmanned aerial vehicles (UAVs), face overheating issues due to the heat generated by components like windings, electrical steel laminations, and magnets, which conventional cooling methods, such as external fans, occupy valuable space and are not suitable for weight and size-constrained applications.
Innovation Solution
An electrical machine design featuring a rotor with radially extending arms equipped with vanes that generate axial airflow over the windings and a heatsink, integrated with a stator, to provide cooling without additional space-consuming components, and a method of mounting the rotor and stator directly to the engine components, eliminating the need for a bearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods like external fans are used, then cooling effectiveness is improved, but device size and weight increase
Solution Approach 1:
The cooling function is merged with the rotor structure by integrating vanes directly into the rotor arms. This combines the rotational component with the cooling component, eliminating the need for separate external fans and reducing overall device weight while maintaining effective cooling through axial airflow generation.
Solution Approach 2:
The rotor serves multiple functions: it generates the magnetic field through permanent magnets and simultaneously provides cooling through integrated vanes that create axial airflow. This multi-functionality reduces the need for additional dedicated cooling components, thereby reducing device weight.
2Temperature
If conventional cooling methods like external fans are used, then cooling effectiveness is improved, but device volume increases
Solution Approach 1:
The cooling function is merged with the rotor structure by integrating vanes directly into the rotor arms. This combines the rotational component with the cooling component, eliminating the need for separate external fans and reducing overall device volume while maintaining effective cooling through axial airflow generation.
Solution Approach 2:
The cooling vanes are nested within the rotor structure itself, with vanes integrated into the rotor arms. This nesting approach allows the cooling function to be embedded within the existing rotational component volume, avoiding additional external space requirements.
3Temperature
If heat is dissipated through casing fins, then cooling is achieved, but device complexity increases
Solution Approach 1:
The cooling function is extracted from the stationary casing structure and transferred to the rotating rotor. By removing the need for external casing fins and replacing them with integrated rotor vanes, the overall cooling system complexity is reduced while maintaining effective heat dissipation through airflow generation.
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
Effectively cools the machine components by axial airflow, maintaining operational temperatures without increasing size or weight, and allows for efficient integration with internal combustion engines.
Implementation Method 1
at least one of the arms comprising a vane which causes an axial airflow as the rotor rotates
Implementation Method 2
a heatsink being disposed inside the yoke and thermally connected thereto
Implementation Method 3
the or each vane being arranged to cause an airflow over the heatsink along passageways which extend between the heatsink and the yoke
Data Source
Figure 1
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Figure 3
AI summary
An electrical machine comprises a stator (11) having a plurality of windings (25) and a rotor (19) having a plurality of permanent magnets (26) arranged to rotate around the windings (25), the magnets (25) being mounted to an outer portion (23) of a rotor body (20), the rotor body (20) further having an inner hub portion (21) and a plurality of circumferentially-spaced arms (22) which extend radially from the hub portion (21) to the outer portion (23) of the body (20), at least one of the arms (22) comprising a vane (24) which causes an axial airflow as the rotor rotates.The axial airflow flows over the windings (25) and helps to prevent overheating without the need for any additional cooling. Since the cooling is conveniently provided by part of the rotor, the machine the machine is simple and compact.