Adhesive-Laminated Stator Core Filler Design for Flatness Stability

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Solution Overview

Problem

Existing adhesively laminated cores in motors suffer from poor flatness and space factor, leading to instability and deterioration of magnetic properties.

Innovation Solution

Incorporating an inorganic filler with controlled particle sizes in the adhesive layer to suppress expansion and contraction, improving the flatness and space factor of the laminated core.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a plurality of thin electrical steel sheets are stacked and integrated by an adhesive, then the core can be formed as a laminated structure, but it becomes difficult to maintain flatness as the number of stacked sheets increases

Engineering Contradiction:
Improvenumber of stacked electrical steel sheetsVSAvoidflatness of laminated core
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent changes the physical and chemical parameters of the adhesive by specifying precise compositional ratios (isocyanate component 5-20 parts, polyester resin 75-85 parts, extender 0-10 parts, pigment 0-5 parts by mass) to optimize the adhesive's bonding strength and flatness-maintaining properties, enabling stable lamination of multiple steel sheets

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite adhesive material consisting of multiple components (isocyanate, polyester resin, extender, and pigment) that work together to provide both strong bonding and flatness maintenance, resolving the contradiction between stacking quantity and flatness precision

Inventive Principle:
Principle #40Composite materials

2Strength

If adhesive is applied to bond electrical steel sheets, then the sheets are integrated into a laminated core, but the accuracy of film thickness and stability of core accuracy deteriorate

Engineering Contradiction:
Improveadhesion strength between steel sheetsVSAvoidaccuracy of film thickness and core stability
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent optimizes the adhesive composition parameters, specifically using polyester resin with number-average molecular weight 1,000-10,000 and acid value 10-50 mg KOH/g, to achieve the right balance between adhesion strength and film thickness control, ensuring stable and accurate lamination

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the adhesively laminated core has poor flatness, then manufacturing is possible, but the core cannot stand upright, becomes tilted, and magnetic properties deteriorate

Engineering Contradiction:
Improvemanufacturability of laminated coreVSAvoidstability and magnetic properties of core
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent adjusts the adhesive formulation parameters including the ratio of isocyanate to polyester resin (5-20:75-85 by mass) and adds extenders and pigments in controlled amounts to achieve optimal bonding strength that ensures both ease of manufacture and reliable upright stability with excellent magnetic properties

Inventive Principle:
Principle #35Parameter changes

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

Enhances the core's ability to maintain flatness and increase the density of magnetic field lines, thereby improving magnetic properties and stability.

Implementation Method 1

the expansion or contraction of the adhesion portion can be suppressed when an inorganic filler is blended with the adhesion portion for adhering the electrical steel sheets to each other

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3902106B1Adhesively laminated core for stator, method of manufacturing the same, and electric motor
Publication Date: 2025.10.29 NIPPON STEEL CORPORATION
  • EP3902106B1 patent drawingFigure 1
  • EP3902106B1 patent drawingFigure 2
  • EP3902106B1 patent drawingFigure 3

AI summary

An adhesively-laminated core includes: a plurality of electrical steel sheets which are stacked on each other and of which both surfaces are coated with an insulation coating; and an adhesion part which is provided between the electrical steel sheets adjacent to each other in a stacking direction and adheres the electrical steel sheets to each other, wherein an adhesive forming the adhesion part contains an organic resin and an inorganic filler, wherein a 50% particle size of the inorganic filler is 0.2 to 3.5 µm, wherein a 90% particle size of the inorganic filler is 10.0 µm or less, and wherein an amount of the inorganic filler is 5 to 50 parts by mass with respect to 100 parts by mass of the organic resin.