Vacuum insulation structures with multiple insulators

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Solution Overview

Problem

Current refrigerator insulation methods fail to effectively maintain low pressure within the vacuum space, leading to thermal bridging and potential deformation or rupture of the inner and external liners due to atmospheric pressure, which compromises the insulating efficiency and structural integrity.

Innovation Solution

A refrigerator cabinet design featuring an inner liner and external wrapper with a gap filled with first and second insulators, where the pressure within the gap is maintained below 506 mbar, using materials like fumed silica and precipitated silica to resist thermal conductivity and atmospheric pressure, and strategically positioning insulators to prevent thermal bridging and deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If vacuum insulation is used to improve thermal insulation efficiency, then thermal insulation performance is improved, but structural integrity deteriorates due to atmospheric pressure causing deformation or rupture

Engineering Contradiction:

Improvethermal insulation efficiencyVSAvoidstructural integrity

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The patent applies different insulator types in different locations: a first insulator (rigid foam board) is positioned at the front flange area where structural support is needed to resist atmospheric pressure, while a second insulator (loose-fill material) is used in other areas for thermal insulation. This local differentiation resolves the contradiction by providing both structural integrity and thermal insulation efficiency.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a composite insulation system combining two different insulator materials with complementary properties. The rigid foam board provides structural strength to prevent deformation, while the loose-fill insulator provides superior thermal insulation. This composite approach resolves the contradiction between maintaining structural integrity and achieving high thermal insulation efficiency.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If multiple insulators are positioned in the gap to improve thermal insulation, then thermal insulation performance is improved, but device complexity increases

Engineering Contradiction:

Improvethermal insulation performanceVSAvoidinsulator arrangement complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The insulation gap is segmented into different zones with different insulator types. The first insulator is positioned specifically at the front flange area, while the second insulator fills the remaining gap space. This segmentation allows each insulator type to perform its specialized function while maintaining a relatively simple overall structure that is easier to manufacture and assemble.

Inventive Principle:

Principle #1Segmentation

3Loss of energy

If expensive insulators are used in critical areas to improve insulation efficiency, then thermal insulation performance is improved, but manufacturing cost increases

Engineering Contradiction:

Improveinsulating efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies the more expensive rigid foam board insulator only at the front flange area where it is most needed for both structural support and thermal insulation. Less expensive loose-fill insulator material is used in the remaining gap areas. This local quality approach optimizes the balance between insulating efficiency and manufacturing cost by strategically placing expensive materials only where critical performance is required.

Inventive Principle:

Principle #3Local quality

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 enhances thermal insulation, reduces the size and weight of the refrigerator while maintaining structural integrity, and provides cost savings by using more expensive insulators in critical areas and less expensive ones elsewhere, effectively addressing thermal bridging and pressure-related issues over the service life.

Implementation Method 1

A first insulator is positioned within the gap and a second insulator is positioned within the gap. The insulators are configured to have low thermal conductivity.

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

the pressure within the gap is maintained below 506 mbar, using materials like fumed silica and precipitated silica to resist thermal conductivity and atmospheric pressure

Methodology Applied

Scientific EffectPressure differential resistance: Pressure Gradient

Data Source

PatentEP3387351B1Vacuum insulation structures with multiple insulators

Publication Date: 2021.10.13 WHIRLPOOL CORP

Figure 1A~1B
Figure 1C
Figure 2A

AI summary

A refrigerator cabinet is provided. The refrigerator cabinet includes an inner liner and an external wrapper. The inner liner is positioned within the external wrapper such that a gap is defined between the external wrapper and inner liner. A first insulator is positioned within the gap, and a second insulator is positioned within the gap. A pressure within the gap is below about 1000 Pa.