Metallic Foil Shield Rotor for High-Frequency Field Filtering
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Solution Overview
Problem
In electric machines, carbon fiber sleeves fail to filter high frequency fields and conduct heat effectively, leading to heat build-up in permanent magnets, which limits rotational speed and increases costs due to material selection and processing requirements.
Innovation Solution
A rotor design featuring a metallic shield made of non-magnetic metallic foil wrapped around permanent magnets, with a carbon fiber sleeve retaining the magnets to the hub, effectively filtering high frequency fields and conducting heat away from the magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If carbon fiber sleeve is used to retain permanent magnets, then weight is reduced and rotational speed is enabled, but heat conduction capability is lost and high frequency field filtering is lost
Solution Approach 1:
The patent employs a composite structure combining carbon fiber sleeve with metallic foil layers. The carbon fiber provides weight reduction and mechanical retention, while the metallic foil layers provide thermal conduction and electromagnetic field filtering. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The retaining structure is segmented into multiple functional layers: an inner metallic foil layer for heat conduction and field filtering, and an outer carbon fiber sleeve for mechanical retention and weight reduction. Each layer performs its specific function, allowing the system to achieve both light weight and effective heat management.
2Speed
If carbon fiber sleeve is used to retain permanent magnets, then rotational speed capability is improved, but high frequency field filtering is lost
Solution Approach 1:
The composite structure combines carbon fiber's high strength-to-weight ratio (enabling high rotational speeds) with metallic foil's electromagnetic shielding properties (filtering high frequency fields). The metallic layer acts as a barrier to harmful electromagnetic harmonics while the carbon fiber enables high-speed rotation.
Solution Approach 2:
The metallic foil acts as an intermediary layer between the permanent magnets and the external environment. It filters high frequency electromagnetic fields before they can affect the magnets, while the carbon fiber sleeve provides the mechanical structure for high-speed rotation.
3Temperature
If metallic sleeve is used instead of carbon fiber, then heat conduction and field filtering are improved, but weight increases
Solution Approach 1:
The patent uses thin metallic foil layers instead of thick metallic sleeves. The foil provides sufficient thermal conduction and electromagnetic filtering in a thin, lightweight configuration. This approach maintains the beneficial thermal and electromagnetic properties of metal while minimizing the weight penalty.
Solution Approach 2:
The composite structure uses thin metallic foil layers combined with carbon fiber to achieve effective heat conduction and field filtering with minimal weight increase. The carbon fiber compensates for the weight of the metallic components while maintaining structural integrity.
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 enhances heat management and reduces weight and inertia, allowing for higher rotational speeds while maintaining cost efficiency by using less material and filtering high frequency fields, thus improving the performance and efficiency of electric machines.
Implementation Method 1
losses generate heat in the system... high frequency fields that enter the permanent magnets generate heat... metallic shield is constructed from a metallic foil... filtering high frequency fields
Implementation Method 2
carbon fiber is ineffective at conducting the resulting heat away from the permanent magnets... metallic shield... conducting heat away from the permanent magnets
Implementation Method 3
carbon fiber retaining sleeve surrounds an outward facing surface of the metallic shield... configured to retain the magnets to the central hub during operation
Implementation Method 4
permanent magnet carrier defines a plurality of permanent magnet receptacles... interference fit over a rotor core... retain the magnets to the central hub during operation
Data Source
AI summary
A rotor for an electric machine has a permanent magnet carrier that defines a plurality of permanent magnet receptacles. A plurality of permanent magnets are received in the receptacles. The magnets are arranged to define at least two magnetic poles of the rotor. A metallic shield surrounds an outward facing surface of the permanent magnets to shield the magnets from high frequency magnetic fields that would cause eddy currents, and thus magnet heating. The metallic shield is constructed from a metallic foil. A carbon fiber retaining sleeve surrounds an outward facing surface of the metallic shield. The carbon fiber sleeve is configured to retain the magnets to the permanent magnet carrier during operation of the electric machine. The permanent magnet carrier is interference fit over a rotor core.