Rotor Magnetization for Deep Embedded Bent-Back Permanent Magnets
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Solution Overview
Problem
Magnetization of permanent magnets embedded in rotor cores with a bent-back shape protruding radially inward is challenging due to difficulty in reaching the bent portion and its vicinity with sufficient magnetic force, especially when the embedding depth exceeds the magnetic pole pitch, leading to inadequate magnetization.
Innovation Solution
An apparatus and method using a magnetizer with a first yoke portion, a second yoke portion, and a magnetization coil to apply a magnetizing magnetic flux through the rotor between the opposing portion of the first yoke and the insertion part or rotary shaft, ensuring sufficient magnetization of the embedded permanent magnets, even in deeply bent shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If permanent magnets are embedded deeply in the rotor core with bent-back shape, then the rotor core strength and magnetic pole structure are improved, but the magnetization of the bent portion becomes insufficient
Solution Approach 1:
A magnetic flux introduction part (second yoke portion) is introduced as an intermediary component to guide magnetic flux into the shaft insertion hole and reach the deeply embedded bent portion of permanent magnets. This mediator enables effective magnetization of areas that would otherwise be inaccessible to conventional external magnetization methods.
Solution Approach 2:
The magnetization approach transitions from purely external radial magnetization to a multi-dimensional approach by introducing magnetic flux through the axial direction via the shaft insertion hole. This allows magnetic flux to reach the bent portion of permanent magnets from both radial and axial directions, ensuring complete magnetization.
2Power
If the embedding depth of permanent magnets exceeds the magnetic pole pitch, then the rotor performance is enhanced, but conventional magnetization methods cannot reach the bent portion with sufficient magnetic force
Solution Approach 1:
The magnetization process is segmented into multiple paths: external radial magnetization through the rotor core, and internal axial magnetization through the shaft insertion hole. This segmentation allows different regions of the deeply embedded permanent magnets to be magnetized through optimal pathways, ensuring complete coverage even when embedding depth exceeds magnetic pole pitch.
Solution Approach 2:
The second yoke portion acts as a magnetic flux mediator that channels flux through the shaft insertion hole to the bent portion of permanent magnets. This intermediary structure enables access to deeply embedded magnets without requiring direct external access to the bent portion.
3Productivity
If a deep folded shape of permanent magnet is used, then the magnetic pole pitch is optimized, but the bent portion becomes difficult to magnetize with conventional methods
Solution Approach 1:
The magnetization system adds an axial dimension to the traditional radial magnetization approach. By introducing magnetic flux through the shaft insertion hole from the axial direction, the system can effectively magnetize the bent portion of deep folded permanent magnets that are inaccessible to purely radial magnetization methods.
Solution Approach 2:
The second yoke portion is pre-installed in the shaft insertion hole before the rotary shaft is inserted. This preliminary action ensures that the magnetic flux path is already in place during the magnetization process, enabling effective magnetization of the bent portion before final assembly is completed.
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 solution effectively magnetizes the entire permanent magnet with a magnetic field strength exceeding the desired lower limit, with more than 90% of the magnetized region achieving sufficient magnetic force, even in deeply folded shapes where conventional methods fail.
Implementation Method 1
The magnetization coil is disposed on the magnetic path of the first and second yoke portions. The magnetizer is configured to magnetize the permanent magnet in an embedded state by energizing the magnetization coil to apply a magnetizing magnetic flux
Data Source
AI summary
An apparatus for manufacturing a rotor includes a magnetizer. The magnetizer is configured to magnetize a permanent magnet in a rotor from outside the rotor. The rotor includes a rotor core having a magnet insertion hole. The permanent magnet is provided in an embedded state in the magnet insertion hole and has a bent-back shape protruding radially inward. The magnetizer includes a first yoke portion, a second yoke portion, and a magnetization coil. The first yoke portion has an opposing portion facing an outer peripheral surface of the rotor. The second yoke portion forms a magnetic path together with the first yoke portion. The magnetization coil is disposed on the magnetic path of the first and second yoke portions. The magnetizer magnetizes the permanent magnet by energizing the magnetization coil to apply a magnetizing magnetic flux at least through the rotor between the first yoke portion and the second yoke portion, which are located opposed to each other in a radial direction of the rotor.