Heatable Tube Conductors With PTC Sheathing Against Overheating

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Solution Overview

Problem

Existing heatable hollow bodies, such as hoses, are prone to overheating due to high input voltages, lacking effective protection mechanisms to regulate electrical heating.

Innovation Solution

Incorporating PTC thermistor sheathing on electrical conductors to self-regulate current flow and heating, reducing overheating risks by increasing electrical resistance with temperature, thus limiting further heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high input voltage is applied to the electrically conductive inner layer for effective heating, then heating efficiency is improved, but overheating risk increases

Engineering Contradiction:
Improveheating efficiencyVSAvoidoverheating risk
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The PTC thermistor sheathing provides automatic feedback control by increasing its electrical resistance when the temperature rises, which automatically reduces the current flow and heating power without requiring external control systems. This self-regulating mechanism ensures that the heating element cannot overheat while maintaining efficient heating at lower temperatures.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The electrical resistance of the PTC thermistor sheathing changes dramatically with temperature - remaining low at operating temperatures for efficient current flow, then increasing sharply when temperature exceeds a threshold. This parameter change automatically limits the maximum heating power and prevents overheating while allowing efficient heating during normal operation.

Inventive Principle:
Principle #35Parameter changes

2Power

If the electrically conductive inner layer is designed to conduct sufficient current at constant voltage, then heating performance is improved, but resistance stability over temperature range becomes problematic

Engineering Contradiction:
Improveheating powerVSAvoidresistance stability
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The PTC thermistor sheathing acts as an intermediary between the power supply and the heating element. It allows sufficient current flow at operating temperatures for effective heating, but automatically limits current when temperature rises by increasing its resistance, thus protecting the system without requiring complex control electronics.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If simple heating structure is used without complex control electronics, then device complexity is reduced, but protection against overheating becomes insufficient

Engineering Contradiction:
Improvecontrol electronics complexityVSAvoidoverheating protection
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The PTC thermistor sheathing makes the heating system self-regulating - it automatically monitors its own temperature through resistance changes and adjusts the current flow accordingly. This eliminates the need for external temperature sensors, control circuits, or protective devices while ensuring reliable overheating protection.

Inventive Principle:
Principle #25Self-service

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 enables self-regulating electrical heating, preventing overheating and ensuring safe operation of heatable hollow bodies, maintaining efficient heating while protecting against excessive temperatures.

Implementation Method 1

at least the sheathing of one of the two electrical conductors and preferably the sheathing of both electrical conductors is designed as a PTC thermistor. This sheathing is designed in such a way that the current can flow from the respective electrical conductor through its sheathing into the electrically conductive layer and vice versa. As the temperature of the heatable layer rises, the temperature of the casing or casings also rises. This increases the electrical resistance of the casing or casings, so that the flow of current between the two electrical conductors via the heatable layer is reduced.

Methodology Applied
Scientific EffectPTC thermistor effect: Thermistor

Implementation Method 2

the inner layer can be heated by means of electricity-heat losses and this heat can be given off as directly as possible to a fluid inside the hose. The electrical heating of the electrically conductive layer can be maintained as before.

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3321553B1Heatable hollow body, in particular heatable tube
Publication Date: 2021.01.27 CONTITECH SCHLAUGH GMBH
  • EP3321553B1 patent drawingFigure 1~2
  • EP3321553B1 patent drawingFigure 3~4

AI summary

The present invention relates to a heatable hollow body (1) for transporting and/or storing liquid, gaseous and/or pasty media, having at least one heatable layer (11) which has an electrically conductive material, a first electrical conductor (13), which is electrically conductively connected to the heatable layer (11), and a second electrical conductor (14) which is electrically conductively connected to the heatable layer (11). The heatable hollow body (1) is characterized in that the first electrical conductor (13) and/or the second electrical conductor (14) has/have a casing (15, 16) at least in sections, preferably completely, which is/are electrically conductive and PTC thermistor is formed / are.