Resin Holder Radial Pressing for Rotor Magnet Positioning
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Solution Overview
Problem
Existing inner rotor motors face challenges in accurately positioning and securing magnets within the rotor core, leading to variations in magnetic characteristics and issues such as cogging and torque ripple due to the lack of effective holding mechanisms for the magnets during manufacturing.
Innovation Solution
A resin holder with specific inner pressing portions is used to position and secure magnets radially within the rotor core, ensuring accurate placement and reducing variations by molding the holder around the magnets and rotor core during the manufacturing process, which includes arranging magnets with radially inner and outer surfaces covered by the rotor core and using grooves to guide the resin for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnets are arranged in the rotor core without a holder mechanism, then the manufacturing process is simple, but the positioning accuracy of magnets deteriorates leading to variations in magnetic characteristics
Solution Approach 1:
A resin holder is introduced as an intermediary component between the magnets and the rotor core. The holder includes pressing portions that radially press the magnets against the rotor core, ensuring accurate positioning and preventing magnet displacement during operation. This mediator structure resolves the positioning accuracy issue without requiring complex mechanical assembly mechanisms.
Solution Approach 2:
The holder is molded in advance together with the magnets and rotor core in a single injection molding process. The pressing portions are formed preliminarily during manufacturing, so that when the rotor is assembled, the magnets are already pre-positioned and pre-pressed by the holder structure, eliminating the need for separate positioning operations.
2Reliability
If magnets are secured with a holding mechanism, then positioning accuracy is improved, but the device complexity increases
Solution Approach 1:
The holder structure merges multiple functions into a single component: it provides radial pressing force to secure magnets, prevents axial displacement through end surfaces, and integrates with the rotor core through the molding process. This consolidation improves reliability while avoiding the complexity of multiple separate securing mechanisms.
Solution Approach 2:
The holder utilizes the resin material's properties and the molding process parameters to achieve magnet securing. By controlling the resin's curing characteristics and molding pressure, the holder naturally develops the required pressing force and structural integrity, eliminating the need for additional mechanical fastening parameters or adjustment mechanisms.
3Manufacturing precision
If resin is poured into grooves to position magnets, then positioning accuracy is enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The resin performs dual functions: it fills the grooves to provide precise positioning references for the magnets, and simultaneously cures to form the holder structure with pressing portions. The resin's own curing process and flow characteristics are utilized to achieve positioning, eliminating the need for separate positioning fixtures or complex assembly operations.
Solution Approach 2:
The grooves are formed preliminarily on the rotor core surface before magnet placement. The resin is then poured into these pre-formed grooves, where it naturally flows to fill the spaces and creates precise positioning features. This preliminary groove formation simplifies the overall process compared to creating complex positioning mechanisms after assembly.
Data Source
AI summary
A rotor includes a rotor core, a first magnet, a second magnet, and a holder made of resin. Both a radially inner surface and a radially outer surface of the first magnet are covered with the rotor core. The second magnet includes a radially inner surface covered with the rotor core, and a radially outer surface exposed from the rotor core. The holder includes a first inner pressing portion and a second inner pressing portion. The first inner pressing portion presses the first magnet radially outward from a radially inner side of the first magnet. The second inner pressing portion presses the second magnet radially outward from a radially inner side of the second magnet. Accordingly, the first magnet and the second magnet are accurately positioned for the rotor core.