One-Piece Ring Magnet Geometry for Low-Cogging Axial Flux Motors
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Solution Overview
Problem
Existing permanent magnet arrangements for axial flux machines, particularly in door drives, require significant manufacturing effort and space due to the need for multiple individual magnets, which can lead to increased noise, vibration, and reduced efficiency from cogging forces.
Innovation Solution
Designing permanent magnets in one piece using powder metallurgy with controlled polarization and forming a multi-pole ring magnet with obliquely angled edges and a coating to reduce manufacturing effort and space requirements, while minimizing cogging forces through varying helix angles and a protective nickel-copper-nickel coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple individual permanent magnets are aligned and attached to a carrier plate, then the permanent magnet arrangement can be manufactured, but the manufacturing effort and time increase significantly
Solution Approach 1:
Multiple individual permanent magnets are merged into a single integral permanent magnet body. The magnet is manufactured as one piece using powder metallurgy processes, eliminating the need to align and attach multiple separate magnets to a carrier plate, thereby reducing manufacturing effort and time
2Ease of operation
If a carrier plate is used to hold permanent magnets, then the permanent magnets can be assembled, but the installation space requirement increases
Solution Approach 1:
The carrier plate is extracted and removed from the design. The integral permanent magnet is designed to function without requiring a separate carrier plate for assembly, thereby reducing the installation space requirement while maintaining operational functionality
3Ease of manufacture
If permanent magnets have conventional shapes, then manufacturing is straightforward, but cogging forces and vibration increase
Solution Approach 1:
The permanent magnet is designed with an asymmetric shape featuring obliquely angled side surfaces rather than conventional symmetric shapes. This asymmetric geometry reduces cogging forces and vibration during motor operation while remaining manufacturable through powder metallurgy processes
4Object-generated harmful factors
If permanent magnets are designed with varying helix angles, then cogging forces are reduced, but manufacturing complexity increases
Solution Approach 1:
The helix angles of the obliquely angled side surfaces are optimized within specific ranges (15-45 degrees) to reduce cogging forces. These parameter changes are implemented through controlled powder metallurgy processes that can vary material density and magnetic properties across different regions of the magnet, achieving the desired angular characteristics without excessive manufacturing complexity
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 approach reduces manufacturing complexity, minimizes installation space, and significantly decreases cogging forces, leading to improved running properties and efficiency by providing a compact, low-noise axial flux machine design.
Implementation Method 1
a weak magnetic field is applied simultaneously during the pressing of the powdered starting material, thereby prescribing a preferential polarization that is usually defined radially or axially
Implementation Method 2
The blanks produced in this way are then magnetized in a magnetization device by strong magnetic fields of different or opposite polarization in adjacent regions of the blank
Implementation Method 3
magnetic field lines running between the north pole and the south pole within the respective permanent magnet run parallel to the machine axis
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a permanent magnet arrangement (1) for use as a rotor or stator of an axial flux machine (10), in particular an axial flux machine (10) of a door drive. The permanent magnet arrangement (1) comprises several permanent magnets (3) arranged in a ring around a central axis (2) and each magnetized in an axial direction parallel to the central axis (2). Adjacent permanent magnets (3) have opposite polarities. All permanent magnets (3) are integrally formed and constitute a multi-pole-pair ring magnet.