Rotor Iron Core Rib Layout for Press-Fit Stress Distribution
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Solution Overview
Problem
The existing rotors for rotating electric machines face a challenge in weight reduction, as expanding the shaft press-fitting hole increases stress on the inner circumference of the rotor iron core, which is concentrated on the outer area housing the magnet, affecting the magnetic characteristics.
Innovation Solution
A rotor design featuring a rib portion with a through-hole forming portion, bridge portions, and a bent portion that connects the inner and outer edge portions, distributing the stress applied by the shaft press-fitting and reducing axial deformation, thereby alleviating stress concentration on the outer edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the shaft press-fitting hole is expanded to reduce weight, then the weight of the rotor is reduced, but the stress on the inner circumference of the rotor iron core increases and concentrates on the outer area housing the magnet
Solution Approach 1:
The rib portion is segmented into multiple bridge portions (first bridge portion and second bridge portion) connected by bent portions. This segmentation divides the stress transmission path into multiple segments, preventing stress concentration at any single location and reducing the overall stress on the outer area housing the magnet.
Solution Approach 2:
Bent portions are introduced to connect the first and second bridge portions, creating curved stress transmission paths instead of straight lines. These curved paths distribute stress more evenly throughout the rib portion, reducing stress concentration on the outer area while maintaining structural integrity.
2Weight of moving object
If the shaft press-fitting hole is expanded to reduce weight, then the weight of the rotor is reduced, but the magnetic characteristics of the rotating electric machine are affected by the concentrated stress
Solution Approach 1:
By segmenting the rib portion into multiple bridge portions connected by bent portions, the stress that would otherwise concentrate on the magnet housing area is distributed throughout the entire rib structure. This prevents stress-induced changes in magnetic characteristics while achieving weight reduction through the lightening hole.
Solution Approach 2:
The bent portions create curved stress paths that redirect and distribute stress away from the magnet housing area. This curvature-based stress distribution protects the magnetic characteristics from stress-induced degradation while maintaining the weight reduction benefit.
3Stress or pressure
If rib portions are added to distribute stress, then stress concentration is reduced, but the weight of the rotor increases
Solution Approach 1:
The lightening hole is strategically positioned and sized to remove material primarily from non-critical areas of the rotor iron core, while the rib portions with bridge structures are maintained in areas requiring stress distribution. This localized material removal approach reduces weight while preserving stress distribution capabilities.
Solution Approach 2:
The rib portion is divided into multiple bridge portions rather than using a solid continuous structure. This segmentation removes unnecessary material to reduce weight while the distributed bridge portions maintain the stress distribution function across the rotor structure.
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 design effectively reduces stress on the outer edge portion by compressing the rib portion, minimizing its impact on the magnetic characteristics and achieving a weight reduction in the rotor.
Implementation Method 1
stress applied to the inner edge portion due to press-fitting of the shaft compresses the rib portion connecting the inner edge portion and the outer edge portion and suppresses an axial deformation of the rib portion
Implementation Method 2
compresses the rib portion connecting the inner edge portion and the outer edge portion and suppresses an axial deformation of the rib portion
Data Source
AI summary
An object of the present invention is to reduce stress caused by press-fitting of a shaft on an outer edge portion side of a rotor. A rotor for a rotating electric machine includes a shaft and a rotor iron core, the shaft coupled to the rotor iron core. The rotor iron core includes: an outer edge portion housing a magnet; an inner edge portion coupled to the shaft; and a rib portion having a lightening portion that is formed inside between the outer edge portion and the inner edge portion. The rib portion includes: a through-hole forming portion connected to the outer edge portion and having a through-hole inside; and a bridge portion connecting the through-hole forming portion and the inner edge portion. The bridge portion includes: a second bridge portion connected to the through-hole forming portion and protruding outward; and a first bridge portion having one end connected to the inner edge portion and another end connected to the second bridge portion. A bent portion is provided at a position connecting the first bridge portion and the second bridge portion.