Conductive Yarn Stability via Composite Filament Structure

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Solution Overview

Problem

Existing electrically conductive yarns lack stability and uniform resistance, leading to unreliable heat emission and comfort issues in products like actively heated clothing, as they are prone to resistance variations due to contact point shifts and material degradation.

Innovation Solution

A composite yarn is created by twisting textile fibers with an electrically conductive filament yarn that has a core of multiple filaments and a surface layer of conductive material, providing stable resistance and flexibility, allowing for predictable conductivity and comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If yarns consisting of a mix of natural and/or synthetic fibers and electrically conductive fibers are used, then the yarn can conduct electricity, but the resistance is unstable and varies over time

Engineering Contradiction:
Improveresistance stabilityVSAvoidcontact point stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses a composite yarn structure combining non-conductive textile fibers with conductive fibers (such as metal or conductive polymer-coated fibers) to create a yarn that maintains stable electrical resistance. The composite structure ensures consistent contact between conductive fibers, preventing resistance variations over time while maintaining textile properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent controls the physical and chemical parameters of the conductive fibers, including their diameter, conductivity, and surface properties, to optimize resistance stability. By carefully selecting and controlling these parameters, the yarn achieves reliable and consistent electrical resistance for heating applications.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the yarn is made strong and abrasion resistant, then the product becomes durable, but the yarn may become less flexible and harder to handle in knitting machines

Engineering Contradiction:
Improveyarn strengthVSAvoidyarn flexibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent applies different properties to different parts of the yarn structure. The core provides strength and durability, while the outer surface maintains flexibility and softness for comfortable wear. This local differentiation allows the yarn to be both strong and easy to handle in textile machinery.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

By combining fibers with different properties in a composite structure, the yarn achieves both high strength for durability and sufficient flexibility for machine handling. The non-conductive textile fibers provide structural integrity while the conductive fibers are distributed to maintain electrical properties without compromising flexibility.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the yarn has suitable resistance for heat emission, then heat can be controlled reliably, but the yarn may become less comfortable against the body

Engineering Contradiction:
Improveheat emission controlVSAvoidcomfort
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The conductive fibers are distributed throughout the yarn structure rather than concentrated on the surface, allowing the outer surface to remain soft and comfortable against the skin while the internal structure provides the necessary electrical conductivity for reliable heat emission control.

Inventive Principle:
Principle #3Local quality

4Reliability

If filament yarn with metal filaments is used for conductivity, then electrical current can be conducted, but the yarn cannot be handled by conventional textile machines and lacks user comfort

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmachine compatibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent combines conventional textile fibers with conductive fibers in a composite yarn that maintains the handling properties and machine compatibility of traditional textiles while providing reliable electrical conductivity. The conductive fibers are integrated into the yarn structure rather than used as separate metal filaments, enabling compatibility with conventional textile machinery and maintaining user comfort.

Inventive Principle:
Principle #40Composite materials

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

The solution achieves stable and reliable heat emission, improved durability, and enhanced comfort by stabilizing conductivity and maintaining performance over time, even under mechanical stress.

Implementation Method 1

an electrically conductive yarn, i.e. a yarn being capable of conducting electrical current

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

heating elements that generates heat as a supplement to the user's body heat

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3394332B1Electrically conductive yarn and a product including the yarn
Publication Date: 2021.04.14 INUHEAT AB
  • EP3394332B1 patent drawingFigure 1~4
  • EP3394332B1 patent drawingFigure 5~7
  • EP3394332B1 patent drawingFigure 8

AI summary

An electrically conductive yarn comprises a fiber yarn (1) which includes textile fibers (2) and electrically conductive fibers (3). The fiber yarn is twisted with a filament yarn (10) which is electrically conductive at least at its surface. The electrically conductive yarn can be used in different products in order to, for instance, create areas for heat emission and conductors for current to and from such areas and other components.