Rotor Core Rolling Direction Offset for Magnetic Imbalance
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Solution Overview
Problem
Existing rotor designs for electric rotating machines suffer from magnetic imbalance due to variations in the direction of rolling of magnetic steel sheets, which cannot be effectively addressed by existing techniques without using multiple types of steel sheets or rotating the sheets relative to each other.
Innovation Solution
The rotor core is formed by laminating annular steel sheets with their directions of rolling offset from imaginary lines X and Y by predetermined angles, allowing for mirror imaging and circumferential positioning without rotating the sheets, thereby reducing magnetic imbalance without using multiple types of steel sheets or rotating them relative to each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the directions of rolling of magnetic steel sheets are offset circumferentially to reduce magnetic imbalance, then magnetic imbalance is reduced, but the circumferential positions of positioning portions become different requiring multiple keyways
Solution Approach 1:
The invention introduces asymmetry by offsetting the direction of rolling from the imaginary line X (which bisects the positioning portion) by a predetermined angle. This asymmetric arrangement allows the rolling direction to vary while maintaining a consistent circumferential position of the positioning portion, thereby reducing magnetic imbalance without requiring multiple keyways.
Solution Approach 2:
Instead of rotating the steel sheets circumferentially to change their rolling direction (which would move the positioning portions), the invention inverts the approach by keeping the positioning portions at fixed circumferential positions and offsetting the rolling direction from the reference line. This inversion allows independent control of positioning and rolling direction.
2Object-affected harmful factors
If steel sheets are rotated relative to each other to reduce magnetic imbalance, then magnetic imbalance is reduced, but additional rotation-stopping mechanisms are required
Solution Approach 1:
The invention performs preliminary action by offsetting the rolling direction from the imaginary line X during the manufacturing of each steel sheet. This pre-established angular offset ensures that when sheets are stacked, their rolling directions are naturally varied without requiring post-assembly rotation or additional stopping mechanisms, thereby reducing magnetic imbalance while maintaining structural simplicity.
3Object-affected harmful factors
If multiple types of magnetic steel sheets are used to reduce magnetic imbalance, then magnetic imbalance is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the parameter of rolling direction angle relative to the imaginary line X, offsetting it by a predetermined angle. This parameter change allows the use of a single type of magnetic steel sheet while achieving varied rolling directions through angular offset, thereby reducing magnetic imbalance without increasing manufacturing complexity or requiring multiple sheet types.
Data Source
AI summary
A rotor includes a rotor core comprised of steel sheets that are laminated in the axial direction of the rotor core and a rotating component configured to rotate together with the rotor core. Each of the steel sheets has a positioning portion for circumferentially positioning the steel sheet with respect to the rotating component and is formed of a rolled steel material. For each of the steel sheets, the direction of rolling of the steel sheet is circumferentially offset from both imaginary lines X and Y by predetermined angles. Each of the steel sheets is shaped so that the circumferential position of the positioning portion thereof remains unchanged when the steel sheet is front-back inverted about the imaginary line X. When viewed along the axial direction, at least one of the steel sheets is front-back inverted with respect to and thus forms a mirror image of the other steel sheets.