BLDC Motor Rotor Core Magnet Insertion Hole Design
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Solution Overview
Problem
In BLDC motors, magnet insertion holes that do not match the shape of the magnets can cause horizontal position scattering over time, leading to unstable cogging torque and deteriorated control characteristics due to reduced adhesive force.
Innovation Solution
A rotor core design with magnet insertion holes that form a pocket at the upper surface, allowing for insulating paper insertion and featuring a magnet fixing rib to secure both ends of the magnet, preventing horizontal movement and maintaining consistent magnetic force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the magnet insertion hole is formed with a shape different from that of the magnet, then the magnet can be inserted easily, but the magnet may move or rotate inside the magnet insertion hole to generate horizontal position scattering
Solution Approach 1:
The magnet insertion hole is designed with different local geometries: an upper portion with a first cross-sectional area that matches the magnet shape for precise positioning, and a lower portion with a second cross-sectional area that facilitates insertion. This local differentiation allows the magnet to be easily inserted while preventing horizontal movement and rotation, thereby resolving the contradiction between insertion ease and position precision.
2Device complexity
If the magnet is secured by adhesive only, then the assembly process is simple, but the adhesive force decreases in long term use leading to position scattering
Solution Approach 1:
The magnet insertion hole is pre-formed with specific geometric features (different cross-sectional areas at upper and lower portions) that create mechanical interference fit with the magnet. This preliminary structural design provides inherent mechanical retention that prevents magnet movement over time, supplementing the adhesive force and ensuring long-term position stability without significantly increasing assembly complexity.
3Ease of operation
If the magnet can move horizontally in the magnet insertion hole, then the assembly process is flexible, but the cogging torque becomes unstable due to inconsistent magnetic force maintenance
Solution Approach 1:
The magnet insertion hole employs local geometric differentiation where the upper portion provides precise horizontal positioning through matched cross-sectional dimensions, while the lower portion allows insertion flexibility. This local quality variation ensures that once inserted, the magnet maintains consistent horizontal position and magnetic force, thereby stabilizing cogging torque while preserving assembly ease.
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
The design stabilizes cogging torque, improving motor control characteristics by ensuring precise magnet positioning and preventing long-term position scattering.
Implementation Method 1
a shaft press-fitted into the shaft hole
Implementation Method 2
a magnet insertion holes penetratively formed at a position near to a periphery of the rotor core member for inserted coupling by a magnet; and a magnet fixing unit formed by stacking the rotor core members each at a predetermined height
Data Source
AI summary
Provided is a rotor core of a motor, the rotor core, the rotor core including a thin disk-shaped rotor core member, a shaft hole penetratively formed at a center of the rotor core member, a shaft press-fitted into the shaft hole, a plurality of magnet insertion holes penetratively formed at a position near to a periphery of the rotor core member for inserted coupling by a magnet, and a magnet fixing unit formed by stacking the rotor core members each at a predetermined height, and press-fitting the shaft into the shaft hole, wherein the rotor core members are stacked at a predetermined height, and the shaft is inserted into the shaft hole.