Heat-Insulating Wall with Layered Cladding to Resist Thermal Stress

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Solution Overview

Problem

Household refrigeration appliances face issues with thermal stress-induced deformation, leading to poor insulation and increased energy consumption, as the thermal expansion coefficients of cladding elements and the heat-insulating core differ, causing warping or buckling of the walls, which can result in inefficient sealing and energy loss.

Innovation Solution

The use of superimposed flat material layers on the narrow sides of the heat-insulating wall, bonded to the core and edge areas, provides dimensional stability without forming thermal bridges, and the layers are connected via buckling zones or welding to enhance rigidity, allowing for a form-fitting enclosure of the core without visible stiffening installations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the wall thickness of the cladding elements is increased to withstand thermal stress, then the resistance to deformation is improved, but the material costs increase significantly

Engineering Contradiction:
Improveresistance to thermal stressVSAvoidmaterial cost
Core Design Contradiction:
StrengthVSQuantity of substance

Solution Approach 1:

The invention uses a composite structure combining a foam core (heat-insulating material) with thin cladding elements. The foam core provides thermal insulation while the cladding elements provide structural strength. This composite approach allows thin cladding to achieve the strength of thick material by relying on the core for insulation and the cladding for structural integrity, thereby reducing material costs while maintaining resistance to thermal stress.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention introduces a third dimension by adding a foam core between the cladding elements. Instead of increasing the thickness of individual cladding layers, the solution creates a multi-layered structure where the foam core adds depth and structural support, allowing thin cladding to withstand thermal stresses through the distributed strength of the entire wall assembly.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If stiffening rails are mounted inside the wall to prevent deformation, then the dimensional stability is improved, but the installation becomes labor intensive and thermal bridges are formed

Engineering Contradiction:
Improvedimensional stabilityVSAvoidinstallation complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The foam core serves a dual function: it provides thermal insulation and simultaneously acts as a stiffening element that prevents deformation. The foam's inherent structural properties eliminate the need for separate stiffening rails, making the wall structure self-supporting. This reduces installation complexity while maintaining dimensional stability, as the foam core inherently resists thermal stress-induced deformation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The foam core performs multiple functions: thermal insulation, structural stiffening, and deformation prevention. By making the core multi-functional, the invention eliminates the need for separate stiffening rails, thereby reducing installation complexity and avoiding thermal bridges that would be created by metal stiffening elements.

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

3Strength

If stiffening rails extend across the major surfaces of the wall to be effective, then the resistance to deformation is improved, but thermal bridges are formed that increase energy requirements

Engineering Contradiction:
Improveresistance to deformationVSAvoidenergy requirement
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The foam core, being a poor thermal conductor, provides structural stiffening without creating thermal bridges. Unlike metal stiffening rails that conduct heat across the wall, the foam core maintains thermal insulation while providing the necessary rigidity to prevent deformation, thereby reducing energy loss.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The foam core inherently provides both insulation and stiffening functions, eliminating the need for separate metal stiffening elements that would create thermal bridges. The foam's cellular structure naturally resists deformation while maintaining thermal break, thus preventing energy loss without additional components.

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

This solution enhances the resistance to thermal stresses, maintains energy efficiency, and reduces material costs by eliminating the need for extensive stiffening installations, while maintaining aesthetic and functional integrity.

Implementation Method 1

a heat-insulating wall

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

The thermal expansion coefficients of the cladding elements differ from each other and from the thermal expansion coefficient of the core

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2705313B1Heat-insulating wall
Publication Date: 2021.06.09 BSH HAUSGERATE GMBH
  • EP2705313B1 patent drawingFigure 1~3
  • EP2705313B1 patent drawingFigure 4~7

AI summary

The invention relates to a heat-insulating wall (21; 51), in particular for a refrigeration device, comprising a heat-insulating core (22), which has first and second main surfaces (25; 27) that lie opposite of one another and at least one narrow side (26) that connects the main surfaces (25; 27), and a covering element (23) formed from a cut of flat material. The covering element extends on at least the first main surface (25) and the narrow side (26) and has several layers (35, 36, 37) of the flat material lying one over the other at least locally on the narrow side (26).