Foamed Dielectric Cable Core with Uniform Cell Structure

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Solution Overview

Problem

Existing foamed coaxial cables face challenges in maintaining electrical characteristics while reducing diameter, as increased foaming rates lead to nonuniform foamed cell diameters, affecting durability, insulation, and mechanical strength.

Innovation Solution

A foamed coaxial cable configuration with a foaming rate of 80% or more, average foamed cell diameter of 10 µm or less, and standard deviation of 2.5 or less, utilizing a fluororesin-based foamed dielectric and a thin solid resin skin layer, is employed to maintain electrical characteristics and reduce cable diameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the foaming rate of the foamed dielectric is increased to reduce the dielectric constant and cable diameter, then the cable diameter is reduced, but the foamed cell diameter becomes nonuniform and enlarged, affecting cable characteristics and durability

Engineering Contradiction:
Improvecable diameterVSAvoidfoamed cell diameter uniformity
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the foaming rate (80% or more), average foamed cell diameter (10 μm or less), and standard deviation of foamed cell diameter (2.5 or less) to achieve both cable diameter reduction and foamed cell uniformity. This involves optimizing the foaming process parameters including temperature, pressure, and foaming agent concentration to maintain cell structure integrity while reducing overall cable size.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining fluororesin as the base material with a foaming agent to create the foamed dielectric. This composite structure allows the dielectric to achieve both low dielectric constant (through high foaming rate) and uniform cell structure (through controlled foaming process), resolving the contradiction between cable size reduction and manufacturing precision.

Inventive Principle:
Principle #40Composite materials

2Reliability

If the foamed cell diameter is reduced to maintain electrical characteristics during cable diameter reduction, then electrical characteristics are maintained, but the foaming rate must be increased significantly, causing foamed cells to aggregate and become nonuniform

Engineering Contradiction:
Improveelectrical characteristicsVSAvoidfoamed cell diameter distribution
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes physical parameters by maintaining average foamed cell diameter at 10 μm or less with standard deviation of 2.5 or less, while achieving foaming rate of 80% or more. This precise parameter control ensures that electrical characteristics are maintained through sufficient foaming, while the foamed cell size remains small and uniform enough to prevent aggregation and maintain compositional stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a foaming agent as an intermediary substance that enables controlled cell formation within the fluororesin matrix. This intermediary allows the dielectric to achieve high foaming rate while maintaining uniform cell distribution, as the foaming agent provides nucleation sites that prevent random cell aggregation and ensure consistent cell size throughout the material.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 results in a cable with excellent electrical characteristics and a reduced diameter, achieving stable transmission performance and mechanical strength, while preventing irregularities and fluctuations in characteristic impedance.

Implementation Method 1

a foamed coaxial cable formed by constituting a dielectric, provided around a center conductor, by a foamed body has a small dielectric constant of the dielectric and enables high-speed transmission of a signal

Methodology Applied
Scientific EffectFoaming: Foam

Data Source

PatentEP3340256B1Cable core and transmission cable
Publication Date: 2020.06.24 JUNKOSHA
  • EP3340256B1 patent drawingFigure 1A~1B
  • EP3340256B1 patent drawingFigure 2
  • EP3340256B1 patent drawingFigure 3~4B

AI summary

[Problem] To provide a technique available for maintaining electrical characteristics while achieving a reduction in the diameter of a cable core. [Means for Solving] A cable core includes: an internal conductor; a foamed dielectric that includes a fluororesin and is formed on the internal conductor by extrusion molding; and a skin layer that covers the foamed dielectric, and is configured such that a foaming rate of the foamed dielectric is 80% or more, an average foamed cell diameter of the foamed dielectric is 10 µm or less, and a standard deviation of a foamed cell diameter of the foamed dielectric is 2.5 or less.