Rotary Electric Machine Bobbin Positioning for Damage-Free Assembly

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Solution Overview

Problem

The positioning of bobbins in rotary electric machines is prone to misalignment, leading to decreased workability and reliability due to potential damage and increased assembly complexity, particularly when using segment coils.

Innovation Solution

The use of protrusions on the stator core projections and flanges on the bobbin ends, which engage in a radial and axial direction to securely fix the bobbin position, ensuring accurate alignment and reducing the risk of damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the projection of the bobbin is fitted into the concave portion at a large angle, then the positioning capability is improved, but the force required for press-fitting increases and the risk of damage to the bobbin increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidbobbin strength
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The invention changes the fitting angle parameter from a large angle to substantially 0 degrees (perpendicular approach), reducing the press-fitting force and risk of damage while maintaining positioning accuracy through the engagement geometry of the projection and recess

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the projection is fitted at an angled position, then positioning is achieved, but damage to the projection may occur and it becomes difficult to check the location after assembly

Engineering Contradiction:
Improvepositioning accuracyVSAvoiddamage detection difficulty
Core Design Contradiction:
Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The invention performs preliminary visual inspection of the projection before assembly to detect any pre-existing damage, and the perpendicular fitting approach prevents additional damage during assembly, making it easier to identify damaged components before they are installed

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If the bobbin is positioned without proper alignment features, then the assembly process is simpler, but the bobbin may move in radial or axial direction and be misaligned

Engineering Contradiction:
Improveassembly structure complexityVSAvoidbobbin alignment precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The projection and recess engagement structure provides self-positioning and self-alignment of the bobbin during assembly, automatically ensuring correct radial and axial positioning without requiring complex external alignment fixtures or procedures

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4611225A1Rotary electric machine
Publication Date: 2025.09.03 HITACHI IND EQUIP SYST CO LTD
  • EP4611225A1 patent drawingFigure 1A
  • EP4611225A1 patent drawingFigure 1B
  • EP4611225A1 patent drawingFigure 2A

AI summary

A stator includes a stator iron core including a plurality of slots, and bobbins fitted into the slots. Each of the bobbins includes flanges provided at both respective ends of the stator in an axial direction, and protrusions provided on the respective flanges. The stator iron core includes projections protruding from inner surfaces of the slots. The bobbins are positioned by engaging the protrusions and the projections to each other.