Heating Device Porous Insulation Moisture Sealing

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Solution Overview

Problem

Existing heating devices for household appliances face challenges in maintaining effective electrical insulation at high humidity levels, particularly when exposed to fluids like water or steam, due to moisture absorption by the insulation layers, which can compromise their performance and longevity.

Innovation Solution

A heating device design featuring a porous insulating layer with sealed micropores using a moisture-impermeable coating applied via a sol-gel process, eliminating the need for encapsulation of the heating conductor and ensuring permanent electrical insulation properties, even in humid conditions. The insulating layer is preferably made of ceramic materials like aluminum oxide, and the heating conductor is made from corrosion-resistant CrNi or FeCr steel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a porous insulating layer is used in heating devices, then thermal insulation performance is improved, but moisture absorption increases at high humidity levels

Engineering Contradiction:
Improvethermal insulation performanceVSAvoidelectrical insulation reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent employs a porous insulating layer made of ceramic materials to provide effective thermal insulation while managing moisture interaction. The porous structure allows for controlled moisture absorption characteristics that prevent electrical conductivity issues.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent uses composite material structures combining ceramic insulating layers with specific pore configurations. This composite approach maintains thermal insulation performance while the ceramic material's inherent properties prevent moisture-induced electrical conductivity, resolving the contradiction between thermal performance and electrical reliability.

Inventive Principle:
Principle #40Composite materials

2Reliability

If the heating conductor is encapsulated to prevent moisture contact, then electrical insulation is improved, but device complexity increases

Engineering Contradiction:
Improveelectrical insulationVSAvoidencapsulation structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the moisture protection function from a separate encapsulation layer and integrates it into the porous insulating layer itself. The insulating layer is designed to inherently resist moisture absorption, eliminating the need for additional encapsulation layers and simplifying the overall device structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The insulating layer serves multiple functions simultaneously: thermal insulation, electrical insulation, and moisture protection. This multi-functional design eliminates the need for separate encapsulation structures, reducing device complexity while maintaining all necessary protection functions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If silicon-based compounds are used to impregnate the insulating layer, then moisture resistance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvemoisture resistanceVSAvoidimpregnation process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the chemical composition parameters of the ceramic insulating layer during manufacturing to inherently provide moisture resistance. By adjusting the ceramic material's chemical properties during the firing process, moisture resistance is achieved without requiring separate impregnation steps, simplifying manufacturing.

Inventive Principle:
Principle #35Parameter changes

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 solution effectively prevents moisture absorption, maintaining the insulating properties of the layer at high humidity levels and enhancing the operational reliability of the heating device by ensuring the heating conductor remains unencapsulated and uncoated, thus improving the device's durability and efficiency.

Implementation Method 1

the moisture-impermeable coating being applied to the respective wall of the cavities in a sol-gel process

Methodology Applied
Scientific EffectSol-gel process: Sol

Data Source

PatentEP3127397B1Heating device, domestic appliance, and method
Publication Date: 2020.08.19 BOSCH SIEMENS HAUSGERATE GMBH
  • EP3127397B1 patent drawingFigure 1
  • EP3127397B1 patent drawingFigure 2~3
  • EP3127397B1 patent drawingFigure 4

AI summary

The invention relates to a heating device (11) for a domestic appliance (1), comprising a substrate (7 - 10), which has a first side (12) facing a fluid (14) to be heated and a second side (13) facing away from the fluid (14) to be heated, a planar heating conductor (15), and an insulating layer (17), which is arranged between the second side (13) of the substrate (7 - 10) and the planar heating conductor (15) and which has pores (18), which are sealed by means of a moisture-impermeable coating (20).