Dynamo-Electric Machine Stator Core Magnetic Flux Interference
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Solution Overview
Problem
In small-sized dynamo-electric machines, magnetic flux interference between the main magnetic pole part and the detection magnetic pole part affects detection accuracy, and modifying the shapes of the rotor and stator cores to mitigate this interference often results in a decrease in output.
Innovation Solution
The dynamo-electric machine incorporates a stator core made of a particulate material with a dust core configuration, where the stator coils are wound around teeth with flange portions extending between the stator coil and the detection magnet, and the rotor core has a field magnet on its outer periphery, with the detection target portion located inward, to minimize magnetic flux interference and prevent eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between the main magnetic pole part and the detection magnetic pole part is reduced to achieve a smaller motor size, then the motor size decreases, but magnetic flux interference increases and detection accuracy decreases
Solution Approach 1:
A magnetic flux shielding structure is introduced as an intermediary element positioned between the main magnetic pole part and the detection magnetic pole part. This shielding structure selectively blocks magnetic flux from the main magnetic pole part while allowing magnetic flux from the detection magnetic pole part to reach the magnetic sensor, thereby eliminating interference and maintaining detection accuracy in a compact motor design
2Measurement precision
If the shapes of the rotor core and stator core are changed to avoid magnetic flux interference, then detection accuracy improves, but the output of the dynamo-electric machine decreases
Solution Approach 1:
Instead of modifying the shapes of the rotor and stator cores, a magnetic flux shielding structure is introduced as a mediator that selectively blocks harmful magnetic flux while preserving the original core shapes, thereby maintaining both detection accuracy and motor output
3Measurement precision
If a magnetic flux shielding structure is added to block magnetic flux from the main magnetic pole part, then detection accuracy improves, but the device complexity increases
Solution Approach 1:
The magnetic flux shielding structure is designed with local quality by creating circumferential differences in magnetic permeability within the rotor core. The shielding portions are strategically positioned to block magnetic flux only in specific directions where interference occurs, while maintaining magnetic flux pathways in other directions, thereby achieving effective shielding with minimal structural 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 configuration effectively suppresses magnetic flux interference, maintaining detection accuracy while increasing the output of the dynamo-electric machine without increasing its axial dimension.
Implementation Method 1
magnetic fluxes generated by magnetic poles of the detection magnetic pole part are detected by the magnetic sensor
Implementation Method 2
magnetic fluxes generated by the main magnetic pole part and currents flowing in the winding can interfere with magnetic fluxes generated by the detection magnetic pole part
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A motor 1 includes a stator 2, a rotor 3, and a detection unit 4. The stator 2 includes a stator core 11 including a yoke 21 and teeth 22. The stator core 11 is a dust core including particles of a magnetic material. The rotor 3 includes a rotor core 31 and a field magnet 32. The detection unit 4 includes a detection target portion 41 and a detection portion 42. Suppose an axial direction of the stator core 11 is a top-bottom direction, front ends of the teeth 22 are provided with flange portions 22b extending upward. The rotor core 31 includes a body portion 31b and a cylinder portion 31c extending upward from an outer peripheral portion of the body portion 31b. The detection target portion 41 is located inward of the cylinder portion 31c in a radial direction of the yoke 21 and is located at an upper side of the body portion 31b in the top-bottom direction. A lower end of the detection target portion 41 is located below an upper end of the cylinder portion 31c and upper ends of the flange portions 22b.