Rotary Electric Machine Rotor Core Asymmetric Stacking
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Solution Overview
Problem
Rotors of rotary electric machines face issues with thickness deviation and stress concentration during production, leading to potential eccentricity and noise when used in liquid cooling environments due to overlapping through holes and concentrated stress, which existing solutions attempt to address through complex configurations and increased thickness requirements.
Innovation Solution
The rotor core is designed with steel plates stacked at rotational angles corresponding to the least common multiple of first and second circumferential intervals, creating a configuration where magnet and through holes are in communication, reducing stress concentration and allowing even refrigerant flow, while maintaining production efficiency by avoiding the need for plate turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If steel plates are stacked with through hole pieces at the same circumferential intervals as magnet insertion hole pieces, then the production process is simplified, but stress concentrates on the inner connecting section and the rotor core requires increased thickness
Solution Approach 1:
The patent applies asymmetry by setting the circumferential interval of through hole pieces (30°) different from that of magnet insertion hole pieces (45°). This asymmetric arrangement prevents the through holes from aligning directly with magnet insertion holes, distributing stress more evenly across the inner connecting sections and reducing stress concentration points.
2Ease of manufacture
If through hole pieces are arranged at the same circumferential intervals as magnet insertion hole pieces, then manufacturing is easier, but oil accumulates in through holes causing eccentricity and noise
Solution Approach 1:
By arranging through hole pieces at 30° circumferential intervals and magnet insertion hole pieces at 45° intervals, the patent creates an asymmetric configuration where through holes do not align with magnet insertion holes. This prevents oil accumulation in through holes that would cause eccentricity and noise during rotation.
Solution Approach 2:
The patent addresses the oil accumulation problem by considering the axial dimension - through holes extend through the stacked steel plates in the axial direction. By offsetting the circumferential positions of through holes from magnet insertion holes, the patent ensures that oil flowing through the rotor core does not pool in the through holes, eliminating the source of eccentricity and noise.
3Strength
If the rotor core thickness is increased to compensate for stress concentration, then structural strength is improved, but the rotor size increases
Solution Approach 1:
The asymmetric arrangement of through hole pieces (30° interval) relative to magnet insertion hole pieces (45° interval) distributes stress more uniformly across the inner connecting sections. This reduces peak stress concentrations, allowing the rotor core to maintain sufficient structural strength without increasing the overall thickness.
Data Source
AI summary
A rotor of a rotary electric machine includes a rotor core. The rotor core has magnet insertion holes which are arranged at first circumferential intervals and in which permanent magnets are disposed. The rotor core includes steel plates, a first core block, and a second core block. The steel plates are stacked in an axial direction of the rotor. The first core block includes first steel plates among the steel plates stacked with rotational stacking at a rotational stacking angle corresponding to a common multiple of a first circumferential interval among the first circumferential intervals and a second circumferential interval among second circumferential intervals. The second core block includes second steel plates among the steel plates stacked with the rotational stacking at the rotational stacking angle from a position shifted by an angle corresponding to the first circumferential interval relative to the first core block.