Method to create vacuum insulated cabinets for refrigerators
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Solution Overview
Problem
Current refrigerator cabinet insulation methods lack an effective impermeable barrier, leading to insufficient thermal insulation due to the use of single-layer plastic and conventional polyurethane foam in vacuum insulated cabinets.
Innovation Solution
A method involving two layers of materials, where the first layer is partially permeable to nitrogen and oxygen, and the second layer is substantially impermeable, with a thermoplastic material being thermoformed to create an annular space and filled with a porous, thermally insulating material like fumed silica to form a vacuum insulated cabinet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer plastic sheet is used for insulation, then the manufacturing process is simple, but the thermal insulation performance is insufficient
Solution Approach 1:
The patent applies composite materials by combining a plastic liner layer with a vacuum insulation layer. The plastic sheet provides structural containment while the vacuum layer provides superior thermal insulation, creating a composite structure that achieves both manufacturing feasibility and high insulation performance.
Solution Approach 2:
The patent uses porous insulating material (such as fumed silica or other vacuum insulation materials) within the annular space. These porous materials provide exceptional thermal insulation properties when placed under vacuum, dramatically reducing heat transfer compared to conventional solid foam insulation.
2Ease of manufacture
If conventional polyurethane foam is used for insulation, then the insulation fills the cavity easily, but the impermeability barrier is insufficient
Solution Approach 1:
The patent employs a plastic liner sheet as a flexible barrier layer that lines the interior cavity. This thin film structure provides an impermeable barrier to moisture vapor and gases, addressing the reliability issue of conventional foam insulation while maintaining ease of installation through its flexible nature.
Solution Approach 2:
The patent creates a composite insulation system combining the plastic liner barrier layer with vacuum insulation material. This composite approach provides both the impermeability function of the plastic layer and the superior thermal insulation of the vacuum layer, overcoming the limitations of using either material alone.
3Ease of manufacture
If a vacuum insulated cabinet is created without an impermeable layer, then the vacuum formation is simpler, but the thermal insulation is insufficient
Solution Approach 1:
The patent uses the plastic liner as a flexible shell that forms the inner boundary of the vacuum space. This thin film structure is easily sealed to create the vacuum enclosure while providing the necessary impermeability to maintain vacuum integrity and provide additional thermal insulation through its low thermal conductivity.
Solution Approach 2:
The patent incorporates porous insulating material within the vacuum space to enhance thermal insulation. The porous structure of materials like fumed silica provides exceptional insulation properties when evacuated, dramatically reducing heat transfer while maintaining vacuum integrity through the plastic liner barrier.
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 approach enhances thermal insulation properties by creating a vacuum-sealed space with superior insulation materials, effectively addressing the impermeability and insulation efficiency issues in existing refrigerator cabinet designs.
Implementation Method 1
At least a portion of the first sheet of material is heated to a temperature at which the first sheet of material can be plastically deformed
Implementation Method 2
A first forming tool is utilized to deform the first sheet of material and form a first intermediate structure
Implementation Method 3
A second forming tool is provided having sidewall portions defining four generally rectangular outwardly facing surfaces
Implementation Method 4
A vacuum is formed in the annular space with an appropriate porous, thermally insulating material such as fumed silica compacted and placed in the annular space to withstand atmospheric pressure
Implementation Method 5
an appropriate porous, thermally insulating material such as fumed silica compacted and placed in the annular space to withstand atmospheric pressure and to provide superior thermal insulation properties
Data Source
Figure 1A~1C
Figure 2A~2F
Figure 3A~4
AI summary
A method of forming a vacuum insulated refrigerator cabinet, the method comprising providing first and second sheets of material. The first sheet of material is thermoformed over a first forming tool forming a first intermediate structure. The first intermediate structure is then thermoformed over a second forming mold to create a second intermediate structure. The second sheet of material is then sealing connected with the second intermediate structure forming an annular space. A vacuum is created in the annular space creating a vacuum insulated cabinet.