Lamellar Stack Magnet Fixing via Elastic Retaining Section

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for fixing permanent magnets in laminated cores of electrical machines often result in damage due to direct contact with punching burrs, leading to asymmetries in magnetic fields and balancing issues, and require additional steps like adhesive coating and burr removal.

Innovation Solution

The use of elastically deformable holding sections with a projection that keeps the contact surface away from the edge area, including a convex shape to prevent contact with punching burrs, allowing for secure and precise magnet fixation without damaging the magnet surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If magnets are fixed directly in the recesses of the laminated core, then the fixation is simple and direct, but the punching burrs on the edge areas damage the magnet surface

Engineering Contradiction:
Improvefixation simplicityVSAvoidmagnet surface damage
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The holding section acts as an intermediary element between the laminated core and the magnet. It provides a contact surface that is spaced away from the punching burrs on the edge area, thereby mediating the fixation process without allowing direct contact between the burrs and the magnet surface. This resolves the contradiction by enabling simple fixation while protecting the magnet.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The holding section extends in the axial direction to create a stepped structure, moving the contact surface away from the plane of the punching burrs. This dimensional change separates the harmful edge areas from the magnet contact area in the axial dimension, allowing fixation without surface damage.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If additional steps like adhesive coating and burr removal are implemented, then magnet surface damage is prevented, but production costs and complexity increase

Engineering Contradiction:
Improvemagnet surface protectionVSAvoidproduction process complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The holding section is designed to automatically provide protection against magnet surface damage through its own geometric structure. The contact surface is inherently spaced away from the punching burrs by the design of the holding section itself, eliminating the need for external protective measures like adhesive coating or burr removal processes. The structure serves its own protective function.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The harmful punching burrs are effectively excluded from the magnet contact area by the holding section's design. The contact surface is extracted from the plane containing the punching burrs, creating a separate zone that does not interact with the magnet. This extraction eliminates the need for additional protective steps.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If the contact surface is close to the edge area for compact design, then the structure is compact, but positioning accuracy and magnetic field symmetry deteriorate

Engineering Contradiction:
Improvestructure compactnessVSAvoidmagnet positioning accuracy
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The holding section creates a localized contact zone with specific geometric properties. The contact surface is positioned at a determined distance from the punching burrs, creating a local quality that ensures accurate magnet positioning. This localized design maintains compactness while achieving the required positioning precision through the specific geometry of the holding section.

Inventive Principle:
Principle #3Local quality

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 solution ensures reliable and precise magnet fixation, reduces production costs, and improves positioning accuracy by avoiding direct contact with punching burrs, thus enhancing the magnetic field symmetry and rotor balancing.

Implementation Method 1

jeweils einen biege- und/oder winkelbaren Haltebereich (5) aufweisend, der eine elastisch verformbare Haltefunktion ausbildet

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3695486B1Electric machine having a lamellar stack for fixing a magnet and a lamellar stack for use in such a machine
Publication Date: 2021.11.10 VOLKSWAGEN AG
  • EP3695486B1 patent drawingFigure 1
  • EP3695486B1 patent drawingFigure 2
  • EP3695486B1 patent drawingFigure 3

AI summary

The invention relates to an electric drive machine having a lamellar stack (1) consisting of a plurality of lamellae (2), stacked one atop the other, and having a plurality of recesses (3), in each of which a magnet (4) is fixed. Each magnet (4) is interlockingly and frictionally fixed in the recess (3) associated therewith, in that individual layered lamellae (2) have a respective protrusion, which has an elastically deformable retaining section, formed by a turn. Said retaining section (5) limits the available cross-sectional area such that the magnet (4) can be inserted into the recess (3) against the elastic reset force of the retaining section (5). In order to prevent possible damage to the magnet (4), the retaining section (5) has a shape projecting in the direction of the recess (3), which is formed by an embossing contour. As a result, a contact surface between the retaining section (5) and the magnet (4) has a distance from a plane, defined by an edge region of the retaining section (5), which is greater than the typical extension of stamping burrs.