Rotor Lamination Stack with Retaining Tabs for Magnet Fixation
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Solution Overview
Problem
Existing laminated rotor cores with open peripheral receiving pockets for permanent magnets face challenges in securely holding magnets due to centrifugal forces during rotation, requiring complex assembly and potential twisting of individual sheets, while closed pockets bury magnets too deeply from the air gap.
Innovation Solution
A laminated rotor core design featuring two types of individual laminations with alternating radial projections, where one type provides supporting projections and the other type has retaining projections with flexible tabs for a form-fit and non-positive joint connection, ensuring reliable magnet holding without twisting, and maintaining magnets close to the air gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial projections are made flexible to enable azimuthal deformation for magnet fixation, then magnet holding reliability improves, but the risk of undesired bending or twisting of the projections increases
Solution Approach 1:
The rotor core is divided into multiple individual laminations, each with its own radial projections. This segmentation allows each projection to be independently designed with specific flexibility characteristics, enabling reliable magnet fixation while controlling unwanted deformation through precise lamination-level design.
Solution Approach 2:
The radial projections are designed with non-uniform cross-sections along their length, creating local variations in flexibility. The projections have greater flexibility at specific locations to enable necessary azimuthal deformation for magnet fixation, while maintaining rigidity in other regions to prevent undesired bending or twisting.
2Reliability
If individual laminations are twisted relative to each other to create clamping effect, then magnet fixation improves, but assembly complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of twisting the laminations to create clamping effect, the invention inverts the approach by making the radial projections themselves flexible and capable of azimuthal deformation. This allows the projections to naturally clamp the magnets during assembly without requiring complex lamination twisting, thereby simplifying the manufacturing process while maintaining reliable magnet fixation.
3Strength
If radial projections are made rigid to maintain structural stability, then rotor structural integrity improves, but the ability to deform azimuthally for magnet fixation decreases
Solution Approach 1:
The radial projections are designed with non-uniform cross-sections that create local flexibility zones. These projections maintain overall structural rigidity for rotor integrity while having specific regions with reduced stiffness that enable the necessary azimuthal deformation for magnet fixation, thus balancing strength and adaptability.
Solution Approach 2:
The rotor core combines multiple laminations with strategically designed projection geometries, creating a composite structure that exhibits both rigidity for structural integrity and localized flexibility for deformation. The alternating patterns of different lamination types create a composite system that achieves both contradictory requirements simultaneously.
4Reliability
If alternating lamination types are used with different projection patterns, then magnet clamping effectiveness improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention combines multiple lamination types with different projection patterns into an alternating sequence, where each type complements the other. The first lamination type provides initial projection support while the second type provides enhanced clamping through different projection geometries, achieving effective magnet clamping through the combined action of alternating patterns.
Solution Approach 2:
The invention varies geometric parameters of the radial projections between alternating lamination types, such as projection height, thickness, or azimuthal position. These parameter changes create complementary clamping effects that improve overall magnet fixation while the systematic alternating pattern helps maintain alignment precision during manufacturing.
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 securely holds magnets in place without undesired bonding, simplifies assembly, and maintains a close magnet-air gap arrangement, providing a reliable and efficient clamping mechanism that compensates for manufacturing tolerances.
Implementation Method 1
The retaining tabs of the second lamination type can elastically deform in the stacking direction, in particular in the insertion direction of the magnets, viewed from the front of the air gap
Implementation Method 2
Existing laminated rotor cores with open peripheral receiving pockets for permanent magnets face challenges in securely holding magnets due to centrifugal forces during rotation
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a rotor lamination stack (3), particularly for an electric motor, comprising individual laminations (4, 5) arranged one above the other in the stacking direction (A), each lamination having a number of recesses (9) formed between radial projections (14, 15) which are aligned with each other in the lamination stack and form circumferentially open receiving pockets (10) for permanent magnets (6). A first type of individual lamination (4) has a number of radial support projections (14) and a second type of individual lamination (5) has a corresponding number of radial retaining projections (15) with retaining tabs (15c) extending in the circumferential direction (11), wherein in the lamination stack the support projections (14) are aligned with the retaining projections (15) and their retaining tabs (15c) project beyond the respective support projection (14) in the circumferential direction (11).