Stator Lamination Press-Fit Locking in Electric Motor Housings

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Solution Overview

Problem

Existing methods for manufacturing electric motors face challenges in creating a robust and efficient connection between the stator lamination stack and the stator housing, particularly in ensuring a positive locking mechanism without complex assembly processes.

Innovation Solution

The method involves using a punch part to press the stator lamination stack into the stator housing, where the individual laminations deflect radially, creating depressions in the housing material, thereby forming a positive-locking connection in the circumferential direction through axial insertion, facilitated by a tool with small contact areas and journals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the stator lamination stack is inserted into the stator housing using conventional methods, then the assembly process is simple, but the connection between the stator lamination stack and stator housing is not robust

Engineering Contradiction:
Improveconnection strengthVSAvoidassembly process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The stator lamination stack performs the locking action itself during insertion. The frustoconical pressing surfaces cause radial expansion of the lamination stack, which automatically creates the positive locking effect in the circumferential direction without requiring additional locking mechanisms or complex assembly steps

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The solution transforms the connection mechanism from a single-dimensional axial insertion to a multi-dimensional effect. The frustoconical pressing surfaces convert axial pressing force into radial expansion, creating circumferential locking through geometric transformation rather than additional circumferential fastening elements

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

2Reliability

If a complex assembly process is used to create a positive locking connection, then the connection between stator components is robust, but the manufacturing process becomes more complex and costly

Engineering Contradiction:
Improveassembly reliabilityVSAvoidmanufacturing ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The insertion and locking functions are merged into a single operation. The frustoconical pressing surfaces enable the stator lamination stack to be inserted and positively locked in the circumferential direction simultaneously, eliminating the need for separate locking steps or additional components

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The stator lamination stack self-locks during insertion through its own radial expansion caused by the frustoconical pressing surfaces. This self-service mechanism ensures reliable circumferential locking without requiring external locking devices or complex assembly procedures

Inventive Principle:
Principle #25Self-service

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 approach allows for a simple, cost-effective manufacturing process that achieves a robust and secure connection between the stator lamination stack and the stator housing, ensuring precise alignment and ease of assembly.

Implementation Method 1

material areas of at least one of the individual laminations of the stator lamination stack extend radially outwards and create depressions in the wall of the receiving bore, in particular in the bore wall of the receiving bore, during pressing

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

the stator lamination stack is positively locked in the circumferential direction by means of the depressions

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

These deflected sections then scratch the stator housing's receiving bore as the stack is moved axially, creating axially extending depressions. These depressions can be described, for example, as grooves or channels. This results in a positive-locking connection between the stator lamination stack and the stator housing in the circumferential direction.

Methodology Applied
Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentEP4150740B1Method for producing an electric motor, and electric motor produced according to the method
Publication Date: 2026.03.25 SEW EURODRIVE GMBH & CO KG
  • EP4150740B1 patent drawingFigure 1
  • EP4150740B1 patent drawingFigure 2

AI summary

The invention relates to a method for producing an electric motor and to an electric motor produced according to the method. The electric motor has a stator laminated core and a stator housing with a receiving bore for receiving the stator laminated core, said stator laminated core having individual laminations. The invention is characterized in that the stator laminated core is inserted into the receiving bore by being pressed in using a punch part, in particular during a pressing-in process, wherein material regions of at least one first individual lamination of the individual laminations of the stator laminated core extend radially outwards, and depressions are produced in the wall of the receiving bore, in particular in the bore wall of the receiving bore, during the pressing-in process. The stator laminated core is held in the circumferential direction in a form-fitting manner by means of the depressions, in particular by the depressions extending radially outwards.