Refrigerator comprising a plastic inner lining
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Solution Overview
Problem
Existing refrigerator designs face issues with polyurethane distribution homogeneity, leading to pocket formation and subsequent collapses on the body walls, which are costly to address using netting and corona processes.
Innovation Solution
A three-layered inner lining structure with a glossy polystyrene upper layer, a chemical-resistant interlayer, and a lower layer with increased surface roughness achieved by adding a chemical foaming agent to the polystyrene-based material, facilitating improved polyurethane adherence and homogeneous distribution without the need for netting or corona processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyurethane is injected into the insulation volume, then insulation is provided, but pockets form inside the polyurethane leading to collapses on the body walls
Solution Approach 1:
The inner lining surface is pre-treated with increased roughness before polyurethane injection. This preliminary surface modification ensures better polyurethane distribution and adhesion during the injection process, preventing pocket formation and subsequent structural collapses.
Solution Approach 2:
The inner lining is designed with differentiated surface properties: the lower layer has increased roughness specifically at the surface contacting the insulation volume to improve polyurethane adhesion, while the upper layer maintains a glossy finish for aesthetic purposes. This localized quality change addresses the distribution issue without compromising overall design.
2Manufacturing precision
If netting is placed on the inner lining surface to improve polyurethane distribution, then homogeneous distribution is achieved, but production costs increase significantly
Solution Approach 1:
The netting component is completely removed from the system. Instead of using a separate netting layer to achieve homogeneous polyurethane distribution, the invention integrates the distribution-enhancing function directly into the inner lining material through increased surface roughness, eliminating the need for additional components and reducing production costs.
Solution Approach 2:
The polyurethane distribution enhancement function is merged with the inner lining structure itself. The increased surface roughness of the inner lining performs dual functions: maintaining structural integrity and ensuring homogeneous polyurethane distribution, thereby combining multiple functions into a single component.
3Manufacturing precision
If corona process is applied to adapt the inner lining with polyurethane, then homogeneous distribution is improved, but production costs increase
Solution Approach 1:
The corona discharge process (a complex electrical/chemical treatment) is replaced with a simpler mechanical solution: increasing the surface roughness of the inner lining through material formulation with foaming agents. This substitution eliminates the need for expensive post-processing equipment and operations while achieving the same adhesion improvement.
Solution Approach 2:
The surface roughness parameter of the inner lining is modified by changing the material composition (adding foaming agents). This parameter change directly improves polyurethane adhesion and distribution homogeneity without requiring additional processing steps, thereby reducing production costs.
4Strength
If inner lining surface roughness is increased to improve polyurethane adherence, then adhesion is enhanced, but material weight increases
Solution Approach 1:
A foaming agent is incorporated into the inner lining material that undergoes phase transition during processing, creating a cellular structure with increased surface roughness. This phase transition approach achieves the desired surface morphology improvement while the cellular structure inherently reduces material density and weight compared to solid material.
Solution Approach 2:
The inner lining is designed with a porous cellular structure created by the foaming agent. This porous structure increases surface roughness for better polyurethane adhesion while simultaneously reducing the overall material density and weight of the inner lining component.
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 ensures cost-effective, homogeneous polyurethane distribution within the insulation volume, preventing collapses and reducing raw material usage while enhancing adherence, thus lowering production costs and improving structural integrity.
Implementation Method 1
the foaming agent added during production of the inner lining to the polystyrene based main material of the lower layer is transitioned to the gaseous phase on the surface of the lower layer contacting the polyurethane
Implementation Method 2
the roughness of its surface contacting the polyurethane is increased by adding a chemical foaming agent to the polystyrene based main material. The foaming agent added during production of the inner lining to the polystyrene based main material of the lower layer is transitioned to the gaseous phase
Data Source
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AI summary
The present invention relates to a refrigerator (1) comprising a body (2), at least one door (3), at least one cooler/freezer compartment (4) in which the food products and beverages are placed, an inner lining (5) made of plastic material by way of extrusion, forming the inner surfaces of the body (2) and the doors (3) facing the compartments (4), an outer wall (6) forming the outer side of the body (2) and the doors (3), and an insulation volume (7) provided between the inner lining (5) and the outer wall (6), into which polyurethane (PU) is injected.