Flat Wire Stator Connections With Partial Stripping for Laser Welding

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Solution Overview

Problem

Existing methods for connecting flat wire ends in stators of electrical machines face challenges in achieving a minimal axial height while meeting electrical specifications, particularly due to thermal damage from laser welding and insufficient clearance and creepage distance.

Innovation Solution

A method for partially stripping insulation on three sides of flat wire ends, leaving one side intact, and connecting them using a laser without filler material, ensuring a precise and efficient electrical connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the winding overhang height is reduced to minimize axial length, then the axial installation space is optimized, but thermal damage to insulation material occurs during laser welding

Engineering Contradiction:
Improveaxial length of statorVSAvoidthermal damage to insulation material
Core Design Contradiction:
Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The insulation material is selectively removed only from specific regions where electrical connection is required, while retaining insulation in other regions. This local differentiation allows laser welding to be performed without thermal damage to insulation, enabling reduced axial length while protecting insulation integrity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The insulation material is removed in advance from the regions where laser welding will occur, before the actual connection process. This preliminary preparation allows the laser to weld the conductor ends without inadvertently heating and damaging the insulation material, thus enabling shorter axial dimensions while protecting insulation.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If more insulation material is removed to facilitate laser connection, then connection efficiency is improved, but electrical insulation between adjacent wires deteriorates

Engineering Contradiction:
Improveconnection efficiencyVSAvoidelectrical insulation between adjacent wires
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The insulation removal is performed selectively only in the regions where electrical connection is required between adjacent conductors. The insulation is retained in all other regions to maintain electrical insulation. This localized approach enables efficient laser connection while preserving the necessary electrical insulation between adjacent wires.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If complete stripping of insulation is performed on all sides, then manufacturing simplicity is improved, but time consumption and material loss increase

Engineering Contradiction:
Improvestripping process simplicityVSAvoidstripping time
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

Instead of completely stripping insulation from all sides of the conductor ends, the method selectively removes insulation only from the specific regions where electrical connection is required. This localized stripping approach reduces both the time consumption and material loss associated with the stripping process, while still achieving the necessary connection quality.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The insulation stripping is performed partially rather than completely - only the necessary portions are removed to enable connection. This partial action approach reduces the overall time and material required for stripping while still achieving sufficient connection quality for laser welding.

Inventive Principle:
Principle #16Partial or excessive action

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 method reduces stripping time, improves insulation, and maintains electrical specifications, allowing for a higher fill factor and efficient use of axial space in stators.

Implementation Method 1

connecting them using a laser

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

connecting them using a laser without filler material

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3529877B1Method for connecting flat wire ends and stator produced in such a way
Publication Date: 2025.10.22 ROBERT BOSCH GMBH
  • EP3529877B1 patent drawingFigure 1
  • EP3529877B1 patent drawingFigure 2~5
  • EP3529877B1 patent drawingFigure 6~7

AI summary

The invention relates to a method for connecting free flat wire ends (4, 5) with a substantially rectangular cross section with four sides (41, 42, 43, 44) of a stator of an electrical machine, comprising the steps of: stripping a first flat wire end (4), sheathed with an insulation material, such that partial stripping is carried out at least on three sides (41, 42, 43) and such that the insulation material remains complete on a fourth side (44) of the first flat wire end (4), and electrically connecting the stripped first flat wire end (4) on the completely stripped side (43) to a second flat wire end (5).