Graphite Intermediate Layer Cookware for Induction Heating Uniformity

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Solution Overview

Problem

Existing cookware technologies, such as high ferritic stainless steel and glass/ceramic types, lack efficient thermal responsiveness and uniformity across various heating methods, leading to suboptimal cooking performance and material limitations in induction cooking.

Innovation Solution

Incorporating a graphite intermediate layer with specific properties, such as density, water pick-up, Taber stiffness, and sulfur content, which couples effectively with a magnetic field to generate heat and provide thermal uniformity, combined with optional insulative materials and metal films to tailor thermal response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high ferritic stainless steel is used for induction cooking, then magnetic field coupling is improved, but thermal responsiveness and uniformity deteriorate

Engineering Contradiction:

Improvemagnetic field coupling efficiencyVSAvoidthermal responsiveness and uniformity

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The invention uses a composite structure with a non-magnetic substrate (aluminum or stainless steel) combined with a graphite intermediate layer. The substrate provides structural support and thermal conductivity, while the graphite layer provides magnetic field coupling for induction heating. This composite approach allows the cookware to respond effectively to magnetic fields while maintaining excellent thermal responsiveness and uniformity, resolving the contradiction between magnetic coupling efficiency and thermal performance.

Inventive Principle:

Principle #40Composite materials

2Temperature

If regular stainless steel is used for conductive heating, then thermal conductivity is improved, but magnetic field coupling deteriorates

Engineering Contradiction:

Improvethermal conductivityVSAvoidmagnetic field coupling

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The invention employs a composite structure where a non-magnetic, thermally conductive substrate (aluminum or stainless steel) is combined with a graphite intermediate layer. The substrate ensures excellent thermal conductivity for even heat distribution, while the graphite layer provides the necessary magnetic field coupling for induction cooking. This resolves the contradiction between thermal conductivity and magnetic field coupling by assigning each function to the material best suited for it.

Inventive Principle:

Principle #40Composite materials

3Temperature

If graphite layer density is increased to improve thermal mass, then thermal uniformity is improved, but water pick-up increases

Engineering Contradiction:

Improvethermal uniformityVSAvoidwater pick-up

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The invention specifies precise parameter ranges for the graphite layer, including density of 0.6-1.8 g/cm³ and sulfur content of 10-500 ppm. By controlling these parameters, the graphite layer achieves optimal thermal uniformity while maintaining appropriate porosity to limit water absorption to less than 30% by weight after 2.5 hours of soaking. This parameter optimization resolves the contradiction between thermal mass and water resistance.

Inventive Principle:

Principle #35Parameter changes

4Productivity

If graphite layer thickness is increased to improve thermal responsiveness, then heating efficiency is improved, but weight increases

Engineering Contradiction:

Improveheating efficiencyVSAvoidcookware weight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

The invention optimizes the graphite layer thickness to a specific range (0.05-5.0 mm) to achieve the best balance between thermal responsiveness and weight. Within this optimized thickness range, the graphite layer provides sufficient thermal mass for efficient and uniform heating while keeping the overall cookware weight manageable. This parameter optimization resolves the contradiction between heating efficiency and weight.

Inventive Principle:

Principle #35Parameter changes

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 graphite intermediate layer enables lightweight, thermally responsive, and uniformly heated cookware suitable for all cooking technologies, reducing hot spots, weight, and material costs while improving cooking efficiency and reducing noise and discoloration.

Implementation Method 1

the graphite layer may have such properties that the graphite layer couples with a magnetic field to generate heat

Methodology Applied

Scientific EffectInduction heating: Induction Heating

Implementation Method 2

provide thermal uniformity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10772463B2Graphite containing article

Publication Date: 2020.09.15 NEOGRAF SOLUTIONS LLC

AI summary

Cookware and other heating articles are included herein. The article may have a substrate forming a bottom surface of the cookware. The article may also have a graphite intermediate layer and cooking/heating surface disposed above the intermediate layers. The graphite layer may have one or more of the following properties: (1) a density of at least 0.64 g/cm3; (2) a water pick-up of a less than 30% by weight after a 2.5 hour soak in water at ambient conditions; (3) a Taber stiffness in the machine direction at least 25% higher than in the transverse direction; and (4) a sulfur content of less than 350 ppm and any combination thereof.