Permanent Magnet Division Surface Coercivity via Groove Diffusion
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Solution Overview
Problem
Permanent magnets divided into multiple parts often experience demagnetization when exposed to strong alternating fields due to lack of diffused highly coercive metal in the interior, leading to reduced performance in rotating electrical machines.
Innovation Solution
A permanent magnet manufacturing method involving the diffusion of a metal with higher coercive force into the interior of the magnet matrix, with cut-out parts such as indentations or grooves to ensure deeper penetration of the coercive metal at division surfaces, thereby maintaining high coercivity across all surfaces, including division surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a permanent magnet is divided into multiple parts, then the magnet can be used in rotating electrical machines with reduced eddy current losses, but the division surfaces expose interior regions lacking diffused highly coercive metal, causing demagnetization risk
Solution Approach 1:
The patent applies preliminary action by forming cut-out parts (grooves or indentations) on the surface of the permanent magnet matrix before dividing it into multiple parts. These cut-out parts are strategically positioned so that when the magnet is divided, the division surfaces coincide with regions that have already been treated with diffused highly coercive metal, thereby ensuring these surfaces maintain high resistance to demagnetization despite being exposed to alternating magnetic fields in rotating electrical machines
2Reliability
If highly coercive metal is diffused from the surface towards the interior of the permanent magnet, then the surface coercivity is increased, but the diffusion depth is limited to a certain range, leaving the interior insufficiently protected
Solution Approach 1:
The patent applies segmentation by creating cut-out parts (grooves or indentations) on the surface of the permanent magnet matrix. These cut-out parts divide the surface into multiple regions, allowing the highly coercive metal to be diffused into specific targeted areas. When the magnet is subsequently divided into multiple parts, the division surfaces coincide with these pre-treated regions, ensuring that even though diffusion depth is limited, the critical division surfaces have sufficient coercivity protection
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 approach enhances the resistance to demagnetization and maintains the performance of rotating electrical machines by ensuring that the division surfaces also have increased coercivity, reducing the likelihood of demagnetization and maintaining torque characteristics over time.
Implementation Method 1
a metal with higher coercive force than a matrix of the permanent magnet is diffused from a surface towards the interior of the permanent magnet
Data Source
AI summary
In permanent magnets formed by division, a cut-out part is provided in a straight line in the matrix of the permanent magnets, a metal increasing the coercive force the permanent magnet matrix is diffused into the interior of the matrix from a surface that includes the surface of the cut-out part of the permanent magnet matrix, and the permanent magnet matrix is divided into multiple permanent magnet parts along the straight cut-out part to form the permanent magnets. An Nd—Fe—B sintered magnet may be used as the permanent magnet matrix, and dysprosium (Dy) may be used as the metal increasing the coercive force of the permanent magnet. Multiple indentations disposed in a straight line may be used as the cut-out parts, or a straight groove may also be used.