Laminated Core Adhesive Structure for Lower Hysteresis Loss
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Solution Overview
Problem
The magnetic properties of existing laminated cores are not adequately improved, leading to suboptimal performance in electric motors.
Innovation Solution
A laminated core with electrical steel sheets coated in an insulation layer, where the sheets are adhered using an adhesive with a sea-island structure composed of a first phase containing epoxy resin, acrylic resin, and a curing agent, and a second phase with an elastomer, optimizing the SP values and volume ratios to enhance adhesion strength and mitigate strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesives are used to adhere electrical steel sheets, then the sheets can be bonded together, but the magnetic properties remain suboptimal due to insufficient strain mitigation
Solution Approach 1:
The adhesive is formulated as a composite material containing two distinct phases: a first phase with epoxy resin, acrylic resin, and curing agent (SP value 8.5-10.7), and a second phase with elastomer (SP value 7.5-8.4). This composite structure enables the adhesive to simultaneously provide strong adhesion and effective strain mitigation, thereby improving magnetic properties and reducing hysteresis loss
Solution Approach 2:
The adhesive is designed with non-uniform local properties through the sea-island structure, where the first phase forms the continuous matrix and the second phase forms dispersed islands. This local differentiation allows specific regions of the adhesive to provide different functions: the first phase provides structural integrity and adhesion, while the second phase provides strain absorption, collectively improving magnetic performance
2Strength
If a single-phase adhesive is used, then the formulation is simple, but the adhesion strength and strain mitigation are insufficient
Solution Approach 1:
The adhesive combines two phases with different SP values and properties. The first phase (epoxy resin, acrylic resin, curing agent) provides strong adhesion strength, while the second phase (elastomer) provides strain mitigation. The sea-island structure with the first phase as continuous matrix and second phase as dispersed islands optimizes both adhesion and strain absorption capabilities
Solution Approach 2:
The adhesive formulation carefully controls the SP values of both phases within specific ranges (first phase: 8.5-10.7, second phase: 7.5-8.4) and maintains a volume ratio where the first phase constitutes 50% or more of the total adhesive volume. These parameter optimizations ensure both phases contribute effectively to adhesion strength while maintaining the sea-island structure for strain mitigation
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 configuration reduces hysteresis loss and improves the magnetic properties of the laminated core, making it suitable for high-performance electric motors.
Implementation Method 1
an adhesion part having a sea-island structure of a first phase which is a sea structure portion and a second phase which is an island structure portion
Implementation Method 2
a first phase containing an epoxy resin, an acrylic resin, and a curing agent
Data Source
AI summary
A laminated core includes a plurality of electrical steel sheets which are stacked on each other and of each of which both surfaces are coated with an insulation coating; and an adhesion part which is provided between the electrical steel sheets adjacent in the stacking direction and adheres the electrical steel sheets to each other, wherein an adhesive for forming the adhesion part includes a first phase and a second phase, wherein the adhesion part has a sea-island structure of the first phase which is a sea structure portion and the second phase which is an island structure portion, wherein the first phase contains an epoxy resin, an acrylic resin, and a curing agent, wherein the first phase has an SP value of 8.5 to 10.7 (cal/cm3)1/2, wherein the second phase contains an elastomer, and wherein the second phase has an SP value of 7.5 to 8.4 (cal/cm3)1/2.