Inset Magnet Rotor Structure Without Fastener Air-Gap Penalty
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Solution Overview
Problem
Existing permanent magnet electric motors face increased manufacturing effort and costs due to additional process steps and mechanical fasteners, which affect electromagnetic design and reduce magnetic field interaction efficiency.
Innovation Solution
A rotor design with radially extending magnet receiving slots and interlocking profiles, using overmolded plastic material to secure magnets, allowing closer proximity to the stator without intervening structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical fasteners are used to attach magnets to the rotor, then the magnets are securely retained against centrifugal forces, but the manufacturing complexity and costs increase, and the electromagnetic design is affected
Solution Approach 1:
The attachment function is merged with the rotor body structure itself. The rotor body includes radially extending magnet receiving slots with interlocking profiles (recesses and protrusions) that directly retain the magnets without separate fasteners. This integration eliminates additional mechanical components while maintaining secure magnet retention against centrifugal forces.
Solution Approach 2:
Mechanical fasteners are extracted/removed from the system. Instead of using separate clamping straps, spring elements, or other mechanical fasteners, the patent uses the rotor body's own structure with built-in interlocking profiles to retain the magnets, eliminating the need for additional fastening components.
2Reliability
If mechanical fasteners are used to attach magnets to the rotor, then the magnets are securely retained, but the electromagnetic design is affected due to magnetically active materials in fasteners
Solution Approach 1:
Magnetically active mechanical fasteners are extracted/removed from the system. The patent replaces them with non-magnetic structural integration where the rotor body's own material (or non-magnetic overmolded material) forms the retention structure, eliminating sources of electromagnetic interference while maintaining magnet retention.
Solution Approach 2:
A non-magnetic intermediary structure is introduced. The rotor body slots and interlocking profiles serve as a non-magnetic mediation structure that retains the magnets without introducing magnetically active materials that would interfere with the electromagnetic field between the rotor and stator.
3Reliability
If attachment structures are arranged radially outwardly from the magnets to retain them against centrifugal forces, then the magnets are securely retained, but the distance between magnets and stator increases, reducing electromagnetic efficiency
Solution Approach 1:
The retention function is merged into the rotor body structure itself rather than being a separate radially outward component. The magnet receiving slots and interlocking profiles are formed within the rotor body, allowing magnets to be retained without adding radial distance between the magnet outer surface and the stator, thus maintaining electromagnetic efficiency.
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
Reduces manufacturing complexity and maintains electromagnetic efficiency by securely attaching magnets without additional fasteners, enhancing motor performance.
Implementation Method 1
Each magnet receiving slot and each magnet can have interlocking profiles that restrict radial movement of the magnet. The interlocking profiles can include a first structure associated with each magnet receiving slot and a second structure associated with each magnet.
Implementation Method 2
The second structure can include an overmolded material, and the overmolded material can define the second structure. The overmolded material can include a plastic material.
Data Source
AI summary
An electric motor including a stator, and a rotor supported for rotation within the stator. The rotor includes a rotor body having a plurality of radially extending magnet receiving slots opening to an outer circumference of the rotor, and a plurality of magnets received in the magnet receiving slots. An outer circumference of the rotor includes surfaces of the magnets and the rotor body.