Rotor Core Injection Gate Positioning for Bonded Magnet Stress Reduction

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Solution Overview

Problem

The injection of bonded magnet material into a skewed laminated core can exert unwanted stress on the core members, potentially breaking them due to the exposure of lamination planes in magnet slots during the injection process.

Innovation Solution

A method involving a molding die with strategically positioned gates that reduce the likelihood of the bonded magnet material hitting the exposed lamination planes, using a magnetic field to orient the magnet material and ensuring the gates align with regions that minimize exposure, thereby reducing stress on the core members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the bonded magnet material is injected into the magnet slots of the skewed laminated core, then the bonded magnets are formed, but unwanted stress is exerted on the core members which may break them

Engineering Contradiction:
Improvebonded magnet formationVSAvoidcore member strength
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent applies preliminary action by pre-positioning the gates in the molding die at specific locations that correspond to regions ensuring a view from one opening to the other opening of the magnet slot along the axial center. This preliminary positioning of the gates before injection ensures that the bonded magnet material is poured in a direction that avoids the exposed lamination planes, thereby preventing stress-induced breakage of core members while still achieving complete filling of the magnet slots

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses the gate positioning as an intermediary mechanism between the injection process and the core members. By strategically locating the gates at positions corresponding to region A, the gate acts as an intermediary that directs the flow of bonded magnet material away from the vulnerable exposed lamination planes, thereby mediating the interaction between the injection process and the core members to prevent harmful stress concentration

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the lamination plane is exposed in the magnet slots to allow material injection, then the bonded magnet material can be injected, but the exposed surface is vulnerable to being hit by the injected material causing breakage

Engineering Contradiction:
Improvematerial injectionVSAvoidcore member integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by differentiating the functional requirements of different regions within the magnet slot. Region A is specifically identified as the area that ensures a view from one opening to the other opening along the axial center, and the gates are positioned to correspond to this specific region. This localized approach allows the exposed lamination plane to remain accessible for material injection while directing the flow away from the vulnerable areas, thereby maintaining both ease of manufacture and core member integrity

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 approach effectively reduces the stress on core members during bonded magnet formation, minimizing the risk of core member breakage and improving magnetic orientation by ensuring uniform spreading of the magnet material.

Implementation Method 1

generating a magnetic field in the cavity (43) of the molding die (40) to magnetically polarize the bond magnet material (26a)

Methodology Applied
Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 2

generating a magnetic field in the cavity (43) of the molding die (40) to magnetically polarize the bond magnet material (26a)

Methodology Applied
Scientific EffectMagnetic polarization: Magnetism

Data Source

PatentEP3309937B1Rotor manufacturing method and rotor
Publication Date: 2020.11.11 DAIKIN INDUSTRIES LTD
  • EP3309937B1 patent drawingFigure 1
  • EP3309937B1 patent drawingFigure 2
  • EP3309937B1 patent drawingFigure 3

AI summary

Disclosed herein is a method for manufacturing a rotor, the method including an injection process of injecting a bonded magnet material (26a) into a cavity (43) of a molding die (40) generating a magnetic field in the cavity (43) so that the bonded magnet material (26a) is poured into each of the magnet slots (24) in the rotor core (21) set in the cavity (43) through one of openings (24a) of each magnet slot (24), wherein the molding die (40) used in the injection process has gates (48) which respectively open at positions corresponding to regions (A), each of which ensures a view from the one of openings (24a) to the other opening (24b) of the magnet slot (24) along an axial center (O) of the rotor core (21).