Rotor Permanent Magnet Retention Spring Effect
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Solution Overview
Problem
Electrical rotors with permanent magnets suffer from magnetic flux leakage and mechanical stress issues due to production tolerances, leading to reduced efficiency and increased production costs.
Innovation Solution
Incorporating recesses between receptacles on a trajectory connecting projecting portions of the rotor, combined with a retention device that provides a spring effect to secure the magnets axially and radially, and using arc-shaped contours to refine the thickness of the rotor body, thereby reducing magnetic flux leakage and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reduced geometric tolerances are applied to retain the magnet axially in the receptacle, then the magnet retention is improved, but the production costs increase and manufacturing difficulty increases
Solution Approach 1:
The retention device is pre-assembled in the receptacle before the magnet is installed. This preliminary action ensures proper positioning and retention geometry is established in advance, allowing standard tolerances to be used during magnet installation while still achieving reliable retention. The retention device acts as a pre-positioned guide that compensates for tolerance variations.
2Loss of energy
If the thickness of the rotor body between receptacle and recess is reduced to minimize magnetic flux leakage, then magnetic flux leakage is reduced, but mechanical strength decreases
Solution Approach 1:
The rotor body exhibits non-uniform thickness distribution: thin sections (1-3mm) are strategically positioned between receptacles and recesses to minimize magnetic flux leakage paths, while thicker sections are maintained in load-bearing regions to ensure mechanical strength. This local variation in thickness optimizes both magnetic performance and structural integrity simultaneously.
3Ease of manufacture
If standard geometric tolerances are used in rotor production, then manufacturing is easier and costs are lower, but magnets may be badly placed inside receptacles leading to centrifugal force issues
Solution Approach 1:
The retention device serves as an intermediary element between the magnet and the receptacle. It compensates for positioning errors caused by standard tolerances by providing a mechanical constraint system that ensures proper magnet placement and retention. The retention device absorbs the tolerance variations and maintains reliable magnet positioning despite standard manufacturing tolerances.
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 arrangement effectively minimizes magnetic flux leakage while maintaining mechanical strength, ensuring the rotor's durability and ease of production, and allows for a homogeneous distribution of magnetic flux and stress distribution, improving the rotor's overall performance and service life.
Implementation Method 1
This retention device advantageously has a spring effect in order to retain the magnets when it is placed in one of the receptacles
Implementation Method 2
it has been found that part of the magnetic flux created by the winding of the rotor passed via leakage paths instead of being channelled into the body of the stator
Implementation Method 3
it has been found that part of the magnetic flux created by the winding of the rotor passed via leakage paths instead of being channelled into the body of the stator
Data Source
AI summary
A rotor with permanent magnets comprising: a stack of laminations forming the core of the rotor having an axis, housings spaced evenly apart on the circumference of the rotor and located in the core of the rotor, some of which receive at least one element in the form of a permanent magnet held radially and axially inside the housing between an inner axial part of the housing and an outer axial part, the inner axial part of the housing comprising two concave portions and a protruding portion extending axially according to the axis, the protruding portion being radially closer to the inner axial face of the magnet than the two concave portions. Moreover, recesses are provided in the core and positioned between the housings on a trajectory successively linking the protruding portions of consecutive housings.