Segmented Stator Core Fracture Surfaces Reduce Magnetic Resistance

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Solution Overview

Problem

Conventional electrical rotating machines face challenges in increasing the number of stator coil turns while minimizing magnetic resistance to enhance magnetic flux density and output torque, as forming the stator core with split components leads to gaps and increased magnetic resistance when trying to increase the number of turns.

Innovation Solution

The stator core is formed using a dust core with particulates of magnetic material, fractured to create irregular fracture surfaces on yoke pieces, allowing for increased contact points and reduced gaps, enabling more turns of the stator coil without increasing magnetic resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the stator core is formed with a plurality of split components to increase the number of stator coil turns, then the ease of coil winding is improved, but the magnetic resistance of the yoke increases due to gaps between contact surfaces

Engineering Contradiction:
Improveease of coil windingVSAvoidmagnetic resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The stator core is divided into a plurality of split components in the circumferential direction, allowing the stator coil to be wound around each tooth more easily. This segmentation enables increased number of coil turns while maintaining manufacturability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The contact surfaces of the split components are formed with curved surfaces instead of flat surfaces. This curvature allows the contact surfaces to fit together more closely, reducing gaps and thereby reducing magnetic resistance while still enabling the split component structure for easier coil winding.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Power

If the number of stator coil turns is increased to increase output torque, then the power output is improved, but the magnetic flux density does not significantly increase due to increased magnetic resistance from split components

Engineering Contradiction:
Improveoutput torqueVSAvoidmagnetic flux density
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

By forming contact surfaces with curved surfaces, the gaps between split components are reduced, which reduces magnetic resistance. This allows the increased number of coil turns to effectively increase magnetic flux density and thereby achieve the desired increase in output torque.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Manufacturing precision

If flat contact surfaces are used between split components, then the manufacturing precision is improved, but the magnetic resistance increases due to gap formation between surfaces

Engineering Contradiction:
Improvecontact surface flatnessVSAvoidmagnetic resistance
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention replaces flat contact surfaces with curved contact surfaces. The curved surfaces allow for better contact between split components, reducing gaps and magnetic resistance, while still being manufacturable with standard precision.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Reliability

If the stator core is formed as an integral structure, then the magnetic resistance is suppressed, but the ease of coil winding is reduced due to narrow intervals between tooth tips

Engineering Contradiction:
Improvemagnetic resistanceVSAvoidease of coil winding
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The stator core is segmented into multiple split components, which increases the interval between tooth tips and allows easier winding of the stator coil while maintaining acceptable magnetic resistance through curved contact surfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The curved contact surfaces of the segmented components reduce gaps and magnetic resistance, compensating for the segmentation and allowing the stator core to behave more like an integral structure magnetically while maintaining the manufacturing advantages of segmentation.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 allows for both an increase in the number of stator coil turns and suppression of magnetic resistance, thereby enhancing the magnetic flux density and output torque of the motor.

Implementation Method 1

A stator core (11) is a dust core that uses particulates including particles of a magnetic material, and includes a plurality of yoke pieces (21a) having fracture surfaces (21b)

Methodology Applied
Scientific EffectFracture Mechanics: Fracture Mechanics

Data Source

PatentEP3145054B1Electrical rotating machine
Publication Date: 2019.08.21 YAMAHA MOTOR CO LTD
  • EP3145054B1 patent drawingFigure 1
  • EP3145054B1 patent drawingFigure 2~3
  • EP3145054B1 patent drawingFigure 4~5

AI summary

Provided is an electrical rotating machine capable of achieving both an increase in the number of turns of a stator coil and a suppression of an increase in the magnetic resistance of a stator core (11). A motor (1) includes a stator (2). The stator (2) includes: a stator core (11) including a cylindrical yoke (21) extending in an axial direction and a plurality of teeth (22) extending inwardly of the yoke (21) from an inner circumferential surface of the yoke (21); and a stator coil (12) wound around the teeth (22). The stator core (11) is a dust core that uses particulates including particles of a magnetic material, and includes a plurality of yoke pieces (21a) having fracture surfaces (21 b) disposed relative to each other along a circumferential direction of the yoke (21). Each of the teeth (22) is provided on each of at least some of the plurality of yoke pieces (21a) having the fracture surfaces (21b). The fracture surfaces (21b) of mutually adjacent yoke pieces (21a) of the plurality of yoke pieces (21a) having the fracture surfaces (21 b) are in contact with each other.