Permanent Magnet Rotor Groove Retention System
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Solution Overview
Problem
Existing permanent magnet rotors in electric machines face bonding issues due to adhesive failures, especially under high RPM conditions and environmental factors like temperature and humidity, leading to unreliable magnet retention.
Innovation Solution
A method and design where permanent magnets with features on each side are positioned around a rotor core with grooves, and a molded material is applied to engage both the magnets and the core, forming a robust retention system that counters centrifugal forces without using adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is used to bond permanent magnets to rotor core, then magnet retention is achieved, but bonding reliability deteriorates under high RPM and environmental conditions
Solution Approach 1:
The patent replaces the chemical bonding system (adhesive) with a mechanical retention system. Grooves are formed in the rotor core and magnets are positioned within these grooves, creating a mechanical interlock that physically retains the magnets without relying on adhesive bonds. This mechanical system is inherently more resistant to environmental degradation.
Solution Approach 2:
The rotor core is segmented with grooves that divide the magnet retention areas into discrete sections. Each groove acts as an independent retention feature, and the magnets are segmented to fit within these grooves. This segmentation allows for localized retention without requiring continuous adhesive coverage, improving overall reliability.
2Ease of manufacture
If adhesive bonding process is used, then magnet attachment is achieved, but manufacturing process control complexity increases
Solution Approach 1:
The complex chemical process control requirements for adhesive application (surface preparation, adhesive mixing, application timing, curing conditions) are replaced with a simpler mechanical process. The grooves are formed during rotor core manufacturing, and magnets are simply positioned within these grooves, eliminating the need for complex adhesive process control.
Solution Approach 2:
The grooves are formed in the rotor core during the initial manufacturing process, before magnet assembly. This preliminary action ensures that the retention features are already in place and properly positioned, simplifying the subsequent magnet attachment process and eliminating the need for complex process control during assembly.
3Reliability
If retaining ring is used to secure magnets, then magnet retention is achieved, but device complexity increases
Solution Approach 1:
The retention function is merged into the rotor core structure itself through the formation of grooves. Instead of adding a separate retaining ring component, the rotor core is designed with integrated grooves that provide both structural support and magnet retention. This merging eliminates additional components and simplifies the overall device structure.
Solution Approach 2:
The rotor core and magnets form a composite structure where the grooves in the rotor core material work together with the magnet geometry to create a unified retention system. This composite approach eliminates the need for separate retaining components while maintaining strong retention capability.
Data Source
AI summary
A method for securing a plurality of permanent magnets about a perimeter of a rotor core is described that includes positioning the plurality of magnets with respect to the rotor core, the magnets including at least one feature formed at each side thereof, each feature opposing a feature formed in an adjacent magnet, and applying a material between the magnets that engages the features formed in the magnets to form a molded material, the material extending into a groove formed within the rotor core such that the molded material operates to engage the rotor core, the engagement of the molded material with the rotor core and the engagement of the molded material with the magnets operative to maintain a position of the magnets with respect to the rotor core.