Rotor Magnetizing Method Reducing Shaft Holding Force
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Solution Overview
Problem
In motor systems with permanent magnet embedded rotors, the second magnetization step requires a strong force to hold the rotor due to attractive or repulsive forces generated by the interaction between the permanent magnet and magnetization flux, making the magnetization process cumbersome and requiring significant jig strength.
Innovation Solution
A magnetizing method involving a rotor with a rotor core and permanent magnet, where the rotor is rotated in a first direction by a first angle and then in a second direction opposite to the first, with the second angle being smaller than the first, to align the magnetization flux and easy magnetization direction more closely, reducing the force required to hold the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotor is rotated by a large angle in the second magnetization step to align magnetization flux with easy magnetization direction, then magnetization efficiency is improved, but the force required to hold the shaft increases due to interaction between permanent magnet and magnetization flux
Solution Approach 1:
The patent changes the rotational angle parameter from a large angle (conventional approach) to a small angle (less than 90 degrees) in the second magnetization step. This parameter change reduces the interaction force between the permanent magnet and magnetization flux while still achieving effective magnetization alignment, thereby resolving the contradiction between magnetization efficiency and shaft holding force requirements
Solution Approach 2:
The patent employs a two-step dynamic magnetization process where the rotor is first rotated to a preliminary position and then to a final position. This dynamic approach allows the magnetization flux to be applied in stages, reducing peak forces on the shaft while ensuring complete magnetization coverage through sequential angular adjustments
2Reliability
If a strong holding force is applied to the shaft during the second magnetization step, then the magnetization process can be completed, but the jig strength and complexity must be increased
Solution Approach 1:
By changing the rotational angle parameter to a small angle in the second magnetization step, the patent reduces the interaction forces that would otherwise require strong jig structures. This allows the use of simpler, weaker holding jigs while still achieving reliable magnetization completion
Solution Approach 2:
The magnetization process is segmented into two distinct steps with different angular positions. The first step establishes preliminary magnetization alignment, while the second step completes the process with minimal force requirements. This segmentation allows each step to be optimized independently, reducing overall system complexity
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 method reduces the force needed to hold the rotor's shaft during magnetization, simplifies the magnetization process, and decreases the magnetization current required, while maintaining efficient magnetization of the permanent magnet.
Implementation Method 1
electric current is supplied to a winding of the stator or the magnetization yoke to generate magnetization flux so that the magnetic member is magnetized
Data Source
AI summary
A magnetizing method includes the steps of preparing a rotor comprising a rotor core having a magnet insertion hole and a permanent magnet provided in the magnet insertion hole, placing the rotor so as to face a tooth around which a winding is wound, rotating the rotor in a first rotating direction by a first angle θ1 from a rotational position where a center of the magnet insertion hole in a circumferential direction of the rotor core faces a middle portion between both ends of the winding in the circumferential direction and supplying electric current to the winding, and rotating the rotor in a second rotating direction opposite to the first rotating direction by a second angle θ2 from the rotational position direction and supplying electric current to the winding. The second angle θ2 is smaller than the first angle θ1.