Rotor Iron Core Rib Configuration for Rotating Electric Machines
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Solution Overview
Problem
Rotating electric machines face challenges in withstanding high-speed rotation while reducing moment of inertia without increasing stress around the internal circumference, and using high-strength materials to address this issue is costly.
Innovation Solution
A rotor design featuring a rotor iron core with a shaft hole, an inner and outer area connected by ribs with a higher number of inner rib joints and portions, which reduces maximum stress and allows for wider interference and larger lightening holes to reduce moment of inertia without the need for high-strength materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the interference of the rotor iron core is widened to withstand high-speed rotation, then the rotational strength is improved, but the stress around the internal circumference increases
Solution Approach 1:
The rotor iron core is segmented into multiple ribs radiating from the inner area to the outer area, creating multiple stress distribution paths. This segmentation allows the stress from wide interference to be distributed across multiple rib structures rather than concentrated in a single continuous structure, reducing the peak stress around the internal circumference while maintaining overall rotational strength.
Solution Approach 2:
Different regions of the rotor iron core are given different structural characteristics - the inner area has a larger cross-sectional area to handle concentrated stress from shaft press-fitting, while the outer area has lighter construction for reduced moment of inertia. The ribs transition between these regions with varying thicknesses, optimizing local stress distribution to accommodate both wide interference and high-speed rotation requirements.
2Speed
If large lightening holes are introduced to reduce moment of inertia, then the rotational speed capability is improved, but the stress around the internal circumference increases
Solution Approach 1:
Large lightening holes are segmented by multiple ribs that radiate through the rotor iron core. These ribs act as structural reinforcements that divide the large holes into smaller effective sections, reducing the moment of inertia while preventing stress concentration around the hole perimeters. The ribs create a lattice structure that maintains strength despite the presence of large voids.
Solution Approach 2:
The lightening holes are designed with asymmetric characteristics - larger in the outer area for maximum moment of inertia reduction, but constrained and reinforced by ribs near the inner area where stress concentration would be most problematic. This asymmetric distribution of hole sizes and shapes allows optimal weight reduction while maintaining structural integrity in high-stress regions.
3Stress or pressure
If high-strength material is used to solve stress issues, then the stress resistance is improved, but the manufacturing cost increases
Solution Approach 1:
Instead of changing the material strength parameter, the invention changes the geometric parameters of the rotor iron core - specifically the rib thickness, rib spacing, and cross-sectional area distribution. By optimizing these geometric parameters, the structure achieves the required stress resistance using conventional materials, avoiding the increased cost associated with high-strength materials while meeting performance requirements.
Data Source
AI summary
A rotor for a rotating electric machine has interference and lightening holes. The rotor includes a shaft and a rotor iron core. The shaft is press fitted in the rotor iron core. The rotor iron core includes a shaft hole, an outer area, an inner area in which the shaft is press fitted, a plurality of ribs connecting the outer area and the inner area. Each of the ribs includes a plurality of outer rib joints adjacent to the outer area, a plurality of outer rib portions adjacent to the outer area, a plurality of inner rib joints adjacent to the inner area, and a plurality of inner rib portions adjacent to the inner area. The outer rib portions are connected to the inner rib portions and the total number of the inner rib joints is larger than that of the outer rib joints.