Rotor Punching Sheet with Asymmetric Arcs for Torque Ripple Reduction
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Solution Overview
Problem
Existing motor technologies face challenges in optimizing counter electromotive force waveform and cogging torque simultaneously, resulting in significant torque fluctuations.
Innovation Solution
A punching sheet for manufacturing a rotor with a specific design featuring an axle hole, outer edge arcs with varying radii, mounting grooves, magnetic isolating slots, and crisscross connecting ribs, which creates a nonuniform air gap between the rotor and stator, improving counter electromotive force waveform and reducing cogging torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform air gap is used between rotor and stator, then the motor structure is simple, but the counter electromotive force waveform is poor and cogging torque ripple is large
Solution Approach 1:
The patent applies asymmetry by designing the rotor punching sheet with an outer edge that includes multiple arcs with different radii of curvature. These arcs are centered at different positions relative to the axle hole center, creating a non-uniform air gap between the rotor and stator. This asymmetric geometric design directly addresses the contradiction by sacrificing structural simplicity to achieve improved counter electromotive force waveform quality and reduced cogging torque ripple.
2Manufacturing precision
If arcs with different radii are used in the outer edge, then the counter electromotive force waveform is improved, but the device structure becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the outer edge of the punching sheet into multiple discrete arc segments. Each arc has a specific radius of curvature and is positioned at a determined location relative to the axle hole. This segmented approach allows the complex non-uniform air gap profile to be constructed from simpler arc elements, making the design more manageable while achieving the desired waveform quality.
3Object-generated harmful factors
If the air gap is made nonuniform, then the cogging torque ripple is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying the radii of curvature and center positions of the multiple arcs that form the outer edge. Specific parameter ranges are established (e.g., arc radii between 0.7R1 and 0.9R1 where R1 is the inner radius of the punching sheet). These controlled parameter variations create the non-uniform air gap profile that reduces cogging torque ripple while maintaining manufacturability within defined precision tolerances.
Data Source
AI summary
A punching sheet used for manufacturing a rotor, including an axle hole, an outer edge, and a plurality of mounting grooves for receiving permanent magnets. The axle hole is disposed at the center of the punching sheet, and the plurality of mounting grooves are disposed in the proximity of the outer edge of the punching sheet. The outer edge of the punching sheet includes a plurality of arcs which have equal length and are connected to one another, and a center of a circle corresponding to each arc deviates from the center of the axle hole.