Heat Retaining Container With Anisotropic Wall Conductivity

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Solution Overview

Problem

Existing heat retaining containers with high thermal conductivity are cooled by heat storage media, leading to reduced cold retention time and temperature irregularities due to external heat conduction, while lowering conductivity results in non-uniform temperature distribution.

Innovation Solution

The heat retaining container design features walls with higher conductivity in the surface direction than in the thickness direction, utilizing thermally conductive fillers with anisotropic shapes and electrical insulation properties, and a laminated structure to enhance temperature uniformity and retention time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the heat conductivity of the inner container is increased to improve cooling efficiency, then the cooling effect is enhanced, but the cold reserving time is reduced due to external heat conduction

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcold reserving time
Core Design Contradiction:
Use of energy by moving objectVSDuration of action of moving object

Solution Approach 1:

The patent applies different heat conductivity characteristics to different directions of the same wall structure. The wall has high heat conductivity in the surface direction (parallel to the inner surface) to distribute heat uniformly, while maintaining low heat conductivity in the thickness direction (perpendicular to the inner surface) to prevent external heat penetration. This directional differentiation resolves the contradiction by optimizing heat transfer locally in each direction.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The wall is constructed as a composite structure with thermally conductive fillers dispersed in a resin matrix. The conductive fillers (such as metal particles or carbon materials) provide high in-plane heat conductivity for uniform temperature distribution, while the resin matrix maintains low through-thickness heat conductivity. This composite material approach enables simultaneous achievement of efficient cooling and extended cold retention.

Inventive Principle:
Principle #40Composite materials

2Duration of action of moving object

If the heat conductivity of the inner container is decreased to reduce external heat conduction, then the cold reserving time is extended, but temperature uniformity in the accommodating space deteriorates

Engineering Contradiction:
Improvecold reserving timeVSAvoidtemperature uniformity
Core Design Contradiction:
Duration of action of moving objectVSTemperature

Solution Approach 1:

The wall structure exhibits anisotropic thermal conductivity with high conductivity in the surface direction and low conductivity in the thickness direction. This local quality differentiation allows the wall to efficiently distribute heat laterally across the surface (improving temperature uniformity) while maintaining resistance to heat penetration from outside (extending cold retention).

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The composite wall structure combines thermally conductive fillers arranged to provide lateral heat distribution with a low-conductivity matrix material. The conductive filler network in the plane direction ensures uniform heat distribution, while the overall composite structure maintains low through-thickness conductivity, simultaneously achieving temperature uniformity and extended cold storage.

Inventive Principle:
Principle #40Composite materials

3Temperature

If high thermal conductivity material is used for the inner container, then the cooling uniformity is improved, but the heat insulation performance deteriorates

Engineering Contradiction:
Improvecooling uniformityVSAvoidheat insulation performance
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The wall employs a composite material system where thermally conductive fillers (metal particles, carbon black, graphite) are dispersed in a resin matrix. This composite structure provides high in-plane heat conductivity for uniform cooling distribution while maintaining low through-thickness heat conductivity for effective heat insulation, resolving the contradiction between cooling uniformity and energy loss.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The thermal conductivity of the wall is optimized locally in different directions: high conductivity in the surface direction for uniform heat distribution and low conductivity in the thickness direction for heat insulation. This directional quality differentiation allows the same wall structure to simultaneously achieve both cooling uniformity and energy conservation.

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

This configuration achieves uniform temperature distribution and extended heat retention by minimizing external heat conduction and maintaining consistent cooling through the use of anisotropic fillers and a laminated wall structure.

Implementation Method 1

heat conductivity of each wall in a surface direction is higher than heat conductivity of the wall in a thickness direction orthogonal to the inner surface of the wall

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

heat conductivity of the wall in the thickness direction is low, the heat conduction from the outside of the heat retaining container to the accommodating space is suppressed

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP4332017B1Heat retaining container
Publication Date: 2026.02.18 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP4332017B1 patent drawingFigure 1
  • EP4332017B1 patent drawingFigure 2
  • EP4332017B1 patent drawingFigure 3

AI summary

A heat retaining container (70) includes: an accommodating space (71); and walls (72) including inner surfaces surrounding the accommodating space (71). Heat conductivity of each wall (72) in a surface direction is higher than heat conductivity of the wall (72) in a thickness direction orthogonal to the inner surface of the wall, the surface direction being orthogonal to the thickness direction and extending along the inner surface of the wall.