Chamfered Insulating Retaining Rings for Permanent Magnet Rotors
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Solution Overview
Problem
Existing permanent magnet rotating electric machines face issues with eddy current loss and centrifugal scattering during high-speed rotation and fluctuating torque, due to the absence of insulating materials on rotor surfaces and complex manufacturing processes involving shrink-fitting of retaining rings, which increase costs and reduce performance.
Innovation Solution
The implementation of chamfered surfaces with insulating coatings on both magnet parts and annular members, forming communication spaces that function as electrically insulating layers, reduces eddy current loss and improves centrifugal endurance by press-fitting anti-scattering rings, eliminating the need for jigs and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If insulating members are used to block eddy current paths, then eddy current loss is reduced, but the structure complexity increases and manufacturing cost increases
Solution Approach 1:
The patent combines the insulating member and the retaining ring into a single integrated component. The retaining ring itself is made of insulating material, eliminating the need for separate insulating members while still blocking eddy current paths between adjacent permanent magnets, thus reducing eddy current loss without increasing structure complexity
Solution Approach 2:
The retaining ring serves multiple functions: it mechanically retains the permanent magnets in place, provides electrical insulation between adjacent magnets to block eddy currents, and maintains the radial position of magnets during rotation. This multi-functionality eliminates the need for additional dedicated insulating components
2Reliability
If retaining rings are shrink-fitted on permanent magnets, then centrifugal endurance is improved, but manufacturing complexity and cost increase due to heating and temperature control
Solution Approach 1:
The patent replaces the thermal shrink-fitting process with a mechanical press-fit process. The retaining ring is pressed onto the permanent magnets using mechanical pressure instead of thermal expansion and contraction, eliminating the need for heating equipment and temperature control systems while still achieving a secure fit that provides centrifugal endurance
Solution Approach 2:
The patent changes the installation method from thermal parameters (heating temperature, cooling contraction) to mechanical parameters (press-fit force, interference fit dimensions). This parameter change simplifies the manufacturing process by eliminating thermal control requirements while maintaining the reliability needed for centrifugal endurance
3Loss of energy
If clearances are formed in permanent magnets to block eddy currents, then eddy current loss is reduced, but magnet torque decreases due to shorter axial length
Solution Approach 1:
The patent extracts the eddy current blocking function from the permanent magnets themselves and relocates it to the retaining ring. By removing insulating clearances from the magnets and placing the insulating retaining ring externally, the full axial length of the magnets can be utilized for torque generation while eddy currents are still blocked by the retaining ring
Solution Approach 2:
The retaining ring acts as an intermediary component that blocks eddy currents between adjacent magnets without requiring modifications to the magnets themselves. The insulating retaining ring mediates the electrical isolation function, allowing the magnets to maintain their full axial length and magnetic properties for optimal torque production
4Loss of energy
If jigs are used to form clearances during manufacturing, then eddy current paths are blocked, but manufacturing cost increases
Solution Approach 1:
The patent merges the eddy current blocking function with the retaining ring structure itself. The insulating retaining ring is manufactured as a standard component without requiring additional specialized jigs or tools, eliminating the need for expensive clearance-forming equipment while still effectively blocking eddy current paths
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 effectively reduces eddy current loss and enhances the rotor's ability to handle high-speed rotation and fluctuating torque, while lowering manufacturing costs and improving thermal control, thus improving the overall performance and reliability of the permanent magnet rotating electric machine.
Implementation Method 1
during high-speed rotation or when fluctuating torque is generated, eddy current loss occurs in permanent magnets 5. Thus, insulating members 8b are used to block eddy current paths.
Implementation Method 2
During high-speed rotation or when fluctuating torque is generated, the permanent magnets 5 may possibly be scattered radially by the centrifugal force.
Data Source
AI summary
A permanent magnet rotating electric machine is provided with: a magnet portion comprising a plurality of permanent magnets forming a plurality of sets each of which is attached annularly and which are disposed along an axial direction of a rotor; and a plurality of anti-scattering rings press-fitted along the axial direction around the outer circumference of the magnet portion forming the plurality of sets. The anti-scattering rings each have: an insulation coating provided on both side surfaces contacting adjacent, other anti-scattering rings; a chamfer provided between the outer circumferential surface and one side surface; and an insulation coating provided on the chamfer.