Solid Fixing Resin for Rotor Magnets

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Solution Overview

Problem

Existing rotor fixing resin compositions using liquid resins face limitations in mechanical strength and efficacy, particularly when attempting to fix permanent magnets, and struggle with filling high concentrations of inorganic fillers like silica, which affects the resin's filling properties and mechanical properties.

Innovation Solution

A fixing resin composition comprising a thermosetting resin with a cresol novolac type epoxy resin, a phenolic resin-based curing agent, and a high content of inorganic filler, optimized for insert molding to achieve a solid state with improved mechanical strength and filling capabilities, including up to 65% to 90% inorganic filler content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a liquid resin is used to fix the permanent magnet, then the resin can be easily filled into the hole portion, but the mechanical strength of the resin is insufficient

Engineering Contradiction:
Improvefilling easeVSAvoidmechanical strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the physical state parameter of the resin from liquid to solid. The solid resin is heated to melt it, then injected into the hole portion, and finally cooled to solidify. This parameter change allows the resin to exhibit both ease of filling (when molten) and high mechanical strength (when solidified), resolving the contradiction between filling ease and mechanical strength.

Inventive Principle:
Principle #35Parameter changes

2Strength

If a high concentration of inorganic filler like silica is added to improve mechanical strength, then the mechanical strength increases, but the filling properties of the resin deteriorate

Engineering Contradiction:
Improvemechanical strengthVSAvoidfilling properties
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent utilizes the parameter change of heating the solid resin to melt it, which significantly reduces the viscosity of the resin. This allows the resin with high inorganic filler content (65-90 mass%) to be easily injected into the hole portion. Upon cooling, the resin solidifies and maintains its high filler content, thus achieving both good filling properties and high mechanical strength.

Inventive Principle:
Principle #35Parameter changes

3Strength

If the resin is in solid state to provide mechanical strength, then the mechanical strength is sufficient, but the resin cannot be filled into the hole portion

Engineering Contradiction:
Improvemechanical strengthVSAvoidfilling capability
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent employs phase transition of the resin between solid and liquid states. The solid resin is heated to undergo melting transition, becoming a molten state that can be easily injected. After injection, the resin cools and undergoes solidification transition, achieving the desired solid state with mechanical strength. This phase transition approach resolves the contradiction between mechanical strength and filling capability.

Inventive Principle:
Principle #36Phase transitions

4Strength

If an epoxy resin with high silica content is used, then the mechanical strength improves, but the resin becomes difficult to process and fill

Engineering Contradiction:
Improvemechanical strengthVSAvoidprocessing complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent simplifies the processing of high-silica epoxy resin by utilizing temperature parameter changes. The solid resin is heated to melt it, reducing viscosity and enabling easy injection. The process avoids complex liquid resin handling while maintaining high filler content, thus reducing processing complexity while achieving high mechanical strength.

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

The composition provides a rotor with enhanced mechanical strength, improved filling properties, and reduced linear expansion differences with electromagnetic steel plates, ensuring durability and reliability under varying temperatures.

Implementation Method 1

a thermosetting resin (A) containing an epoxy resin (A1)... a curing agent (B)

Methodology Applied
Scientific EffectCuring reaction: Chemical Bonding

Data Source

PatentEP3859944B1Fixing resin composition for use in rotor
Publication Date: 2023.06.28 SUMITOMO BAKELITE CO LTD
  • EP3859944B1 patent drawingFigure 1
  • EP3859944B1 patent drawingFigure 2
  • EP3859944B1 patent drawingFigure 3

AI summary

A fixing resin composition used for forming a fixing member in a rotor provided with a rotor core fixed and installed on a rotating shaft, in which a plurality of hole portions arranged along the peripheral portion of the rotating shaft are formed, a magnet inserted in the hole portion, and the fixing member provided in a separation portion between the hole portion and the magnet. The fixing resin composition includes a thermosetting resin (A) containing an epoxy resin (Al), a curing agent (B), and an inorganic filler (C). The content of the inorganic filler (C) is equal to or more than 50% by mass and equal to or less than 93% by mass, based on 100% by mass of the total content of the fixing resin composition. The fixing resin composition is in a solid state.