Rotor Bending Part Reduces Magnetic Flux Leakage in Direct Drive Motors
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Solution Overview
Problem
Existing motors suffer from efficiency degradation due to leaked magnetic flux and increased cogging torque, leading to vibration and noise, particularly in direct drive type washing machines, where the magnetic flux from permanent magnets leaks through the rotor's side wall and base parts, and the square wave magnetizing form contributes to torque ripple.
Innovation Solution
The motor design includes a rotor with a base part and side wall formed from a magnetic material, where the permanent magnet is positioned with a larger spacing distance from the base part and a curved surface to minimize magnetic flux leakage and cogging torque, featuring a curvature radius that reduces radial thickness from the center to the circumference, and a bending part to reinforce intensity, allowing precise magnet fixation without a step for reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the permanent magnet is positioned closer to the stator to increase magnetic interaction, then the motor efficiency is improved, but the magnetic flux leakage through the rotor base part and bending part increases
Solution Approach 1:
The patent introduces a new spatial dimension by adding a bending part that extends in the radial direction, creating a three-dimensional magnetic flux path structure. This allows the magnetic flux to be guided through a curved path from the permanent magnet, through the bending part, to the stator, effectively separating the flux path from the rotor base part and reducing leakage while maintaining strong magnetic interaction.
Solution Approach 2:
The bending part acts as an intermediary magnetic conductor between the permanent magnet and the stator. It provides a dedicated magnetic flux path that mediates the magnetic interaction, allowing efficient flux transfer while preventing flux leakage through the rotor base part by directing flux through this intermediate structure.
2Power
If the permanent magnet height is increased to strengthen magnetic field, then the motor power is improved, but the magnetic flux leakage through the rotor base part increases
Solution Approach 1:
The bending part creates a vertical magnetic flux path structure that accommodates taller permanent magnets. By extending the magnetic flux path in the radial direction through the bending part, the design can utilize higher permanent magnets for increased power output while the curved geometry naturally guides the flux away from the rotor base part, preventing leakage.
3Ease of manufacture
If the rotor structure is simplified for ease of manufacture, then the manufacturing cost is reduced, but the magnetic flux leakage increases
Solution Approach 1:
The bending part is integrated with the rotor base part as a single molded structure, combining two functional elements into one manufacturing step. This merging maintains manufacturing simplicity while the bent geometry provides the necessary magnetic flux guidance to reduce leakage, achieving both ease of manufacture and reduced energy loss.
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 design minimizes magnetic flux leakage, reduces cogging torque, and decreases vibration and noise, enhancing motor efficiency and manufacturing simplicity, while allowing for precise magnet fixation and reduced material costs.
Implementation Method 1
a rotating magnetic field is generated between the coil wound on the stator and a permanent magnet of the rotor, thereby rotating the rotor
Implementation Method 2
the magnetic flux from the permanent magnet 28 of the rotor 20 does not enter the stator 10 but enters an adjacent rotor 20, thereby generating a leaked magnetic flux
Data Source
AI summary
The present invention relates to a motor. A motor including a stator and a rotor that is rotatably provided at an outer side in a radial direction of the stator, the rotor comprising: a base part; a side wall part that is integrally formed with the base part and vertically extended with respect to the base part; and a permanent magnet that is provided at an inner side of the side wall part, wherein a spacing distance from an inner side surface of the base part to a lower end of the permanent magnet is formed to be larger than a radial thickness of the permanent magnet.