Axial-Gap Stator Tooth Assembly for Magnetic Flux Contact

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Solution Overview

Problem

Existing axial-gap-dynamoelectric machines face challenges in enhancing magnetic flux density and assemblability of teeth to the base yoke, as the gap between teeth and the base yoke hinders magnetic flux flow and complicates assembly due to the difference in materials and shapes.

Innovation Solution

The configuration includes a stator core with pressed powder teeth and resin bobbins, where the teeth are shaped to increase the space factor of coils and positioned using protrusions to minimize friction and gaps, allowing efficient magnetic flux flow while enhancing assemblability by using resin bobbins to press the teeth against the base yoke.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the teeth are shaped to increase the space factor of coils (trapezoidal shape with larger outer-end circumference), then the magnetic flux density is enhanced, but the assemblability of teeth to the base yoke deteriorates due to increased friction and contact during insertion

Engineering Contradiction:
Improvespace factor of coilsVSAvoidassemblability of teeth to base yoke
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

A resin bobbin is introduced as an intermediary component between the tooth and the base yoke. The resin bobbin has a cylindrical shape that fits within the tooth hole, and its outer surface is coated with a low-friction material (such as PTFE) to reduce friction during tooth insertion. This intermediary structure allows the tooth to be inserted smoothly into the base yoke while maintaining the desired trapezoidal shape for high space factor, thereby resolving the contradiction between enhanced magnetic flux density and improved assemblability

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If a gap is formed between the teeth and the base yoke to prevent shaving during assembly, then the assemblability is improved, but the magnetic flux flow from teeth to base yoke is hindered

Engineering Contradiction:
Improveassemblability of teeth to base yokeVSAvoidmagnetic flux flow efficiency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The resin bobbin serves as a mediator that fills the gap between the tooth and the base yoke. The resin material is magnetically permeable and provides a smooth, low-friction surface that prevents shaving during assembly while maintaining continuous magnetic flux paths. The resin bobbin's presence eliminates the need for intentional gaps, allowing the tooth to be in direct contact with the base yoke through the resin medium, thus ensuring both easy assembly and efficient magnetic flux flow

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If the teeth are made of pressed powder iron core material, then the manufacturing flexibility and shape precision are improved, but the fragility increases making careful handling necessary during assembly

Engineering Contradiction:
Improveshape precision of teethVSAvoidfragility of teeth
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The resin bobbin is installed in the tooth hole beforehand to provide cushioning and protection during the tooth insertion process. The resin material acts as a shock-absorbing medium that prevents direct impact and mechanical stress on the fragile pressed powder tooth during assembly. This beforehand cushioning allows the precise pressed powder teeth to be assembled without risk of damage, maintaining both shape precision and structural integrity

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 enhances magnetic flux density and assemblability by increasing the space factor of coils and reducing friction during assembly, ensuring efficient magnetic flux flow between the teeth and base yoke.

Implementation Method 1

reducing friction during assembly

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

ensuring efficient magnetic flux flow between the teeth and base yoke

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentEP4071978B1Axial-gap-dynamoelectric machine
Publication Date: 2023.11.29 YAMAHA MOTOR CO LTD
  • EP4071978B1 patent drawingFigure 1
  • EP4071978B1 patent drawingFigure 2
  • EP4071978B1 patent drawingFigure 3

AI summary

An axial-gap-dynamoelectric machine that allows magnetic fluxes to flow efficiently while enhancing assemblability of pressed powder teeth to a base yoke is provided. An axial-gap-dynamoelectric machine X includes resin bobbins 9 having positioning protrusions 9c, and a base yoke 5 having a plurality of tooth holes 6 and positioning holes 5a. In each tooth hole 6, a circumferential length of a tooth-hole-radial-direction-outer-end surface 6c is larger than a circumferential length of a tooth-hole-radial-direction-inner-end surface 6a. Each of the plurality of pressed powder teeth 8 has a columnar shape in which a circumferential length of a pressed-powder-tooth-upper surface 8b is larger than a circumferential length of a pressed-powder-tooth-bottom surface 8a. The positioning protrusions 9c are inserted in the positioning holes 5a, and press the pressed powder teeth 8 against the base yoke 5 inward in the radial direction of a stator core 7 such that the pressed-powder-tooth-bottom surface 8a is brought into contact with the tooth-hole-radial-direction-inner-end surface 6a and the pressed-powder-tooth-oblique surface 8c is brought into contact with the tooth-hole-circumferential-direction-end surface 6c.