Bendable Vacuum Insulation Core Structure for Curved Heat Retention
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Solution Overview
Problem
Vacuum thermal insulators with fibers oriented in the thickness direction due to processing methods, such as clamping or compression-molding, lead to increased heat conduction and deterioration of insulation performance when bent, as creases form and fibers are misaligned, affecting both flat and curved surface attachments.
Innovation Solution
A vacuum thermal insulator with a core formed of a single fiber sheet or lamination of sheets, where thickness-direction fibers intersect plane-direction fibers, and fiber recesses are created by needle-punching, ensuring the relationship t / Px ≤ 1, where t is the thickness and Px is the interval between thickness-direction fibers, to maintain insulation performance during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a vacuum heat-insulating panel is used, then heat insulation performance is improved, but brittle fracture occurs due to low-temperature embrittlement
Solution Approach 1:
The patent uses a composite structure consisting of a foam core layer and a skin layer. The skin layer is made of a polymer composition containing a specific rubber component (30-70 mass% of the polymer composition) that maintains flexibility at low temperatures. This composite structure combines the insulating properties of the foam core with the impact resistance and low-temperature flexibility of the rubber-containing skin layer, resolving the contradiction between heat insulation and impact resistance.
Solution Approach 2:
The patent modifies the chemical composition parameters of the skin layer by specifying precise ranges of rubber content (30-70 mass%), glass transition temperature (-50°C to 0°C), and molecular weight (10,000 to 1,000,000). These parameter changes ensure the skin layer maintains adequate impact resistance and flexibility at low temperatures while working in conjunction with the vacuum heat-insulating core, thereby preventing brittle fracture.
2Strength
If conventional insulation materials are used, then impact resistance is maintained, but heat insulation performance is insufficient
Solution Approach 1:
The insulation structure is segmented into two distinct functional layers: a vacuum heat-insulating core layer for maximum thermal insulation performance, and a skin layer with rubber-containing polymer composition for providing impact resistance and flexibility. This segmentation allows each layer to optimize its specific function, with the core providing superior heat insulation and the skin providing mechanical durability.
3Strength
If the rubber component content is increased to improve low-temperature flexibility, then impact resistance is improved, but processing difficulty increases
Solution Approach 1:
The patent specifies precise parameter ranges for the rubber component including glass transition temperature (-50°C to 0°C), molecular weight (10,000 to 1,000,000), and content (30-70 mass%). These controlled parameter changes balance low-temperature flexibility with processing feasibility, avoiding both excessive rubber content that would cause processing difficulties and insufficient content that would fail to provide adequate impact resistance.
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 allows for easy bending of vacuum thermal insulators while preventing heat insulation fibers from shifting into the thickness direction, thereby maintaining or improving insulation performance, even when formed in curved shapes, by restricting fiber movement and reducing gas heat conduction.
Implementation Method 1
a vacuum heat-insulating core
Implementation Method 2
heat-insulating performance
Implementation Method 3
impact resistance
Implementation Method 4
glass transition temperature
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A vacuum thermal insulator includes a core (3) that is formed of a single fiber sheet comprising heat insulation fibers (5) extending in a plane direction or of a plurality of such fiber sheets laminated; and an enclosure (4) that accommodates the core (3). At least a part of the vacuum thermal insulator can be bent in a curved shape, and the fiber sheet includes a plurality of thickness-direction fibers (6), which are formed by causing some of the heat insulation fibers (5) to extend in a thickness direction of the fiber sheet, and has a plurality of fiber recesses provided in at least one surface thereof.