Rotor Bridge Inflection Points for Stress Mitigation
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Solution Overview
Problem
Rotors of rotary electrical machines face stress concentration issues in magnet insertion holes, limiting high-speed rotation due to mechanical strength constraints against centrifugal forces.
Innovation Solution
Incorporating a bridge portion with two inflection points on the outer circumference between adjacent magnet insertion holes in the rotor core to distribute stress and enhance mechanical strength, allowing for higher rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotor is designed for high-speed rotation, then the rotation speed increases, but stress concentration occurs in the magnet insertion holes limiting mechanical strength
Solution Approach 1:
The bridge portion is divided into multiple segments by introducing inflection points, which segment the stress distribution path. This segmentation allows the stress to be distributed across multiple regions rather than concentrated at single critical points, enabling the rotor to withstand higher centrifugal forces at high rotation speeds
Solution Approach 2:
The bridge portion is designed with non-uniform cross-sectional area, being thicker at the inflection points and thinner in between. This local quality variation optimizes the stress distribution, providing enhanced strength at critical locations while reducing material usage in less critical areas, thus improving overall mechanical strength against centrifugal force
Data Source
AI summary
Provided are a rotor of a rotary electrical machine, a rotary electrical machine, and a vehicle, which enable mitigation of stress concentration generated in a magnet insertion hole of a rotor core and high-speed rotation. A rotor 250 of a rotary electrical machine includes: a rotor core 252 including a plurality of magnet insertion holes 253 for each magnetic pole; and permanent magnets 254 inserted into the magnet insertion holes, in which a bridge portion 260, which mechanically connects a rotor core portion 256 on the outer circumferential side of the magnet insertion holes 253 and a rotor core portion 263 on the inner circumferential side of the magnet insertion holes 253, is provided between the adjacent magnet insertion holes, and the bridge portion 260 has two inflection points 266a and 266b on the outer circumferential side of the bridge portion 260.