Cooking vessel bottom

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Solution Overview

Problem

Cooking utensils for induction hobs lack energy efficiency due to suboptimal design of heating layers, leading to excessive eddy current losses and inefficient heat transfer.

Innovation Solution

A layer system comprising a heating layer with high electrical conductivity (≥10^4 S/m) and thermal conductivity (≥15 W/m/K), a magnetic layer with high relative permeability (≥10) adjacent to the heating layer to enhance magnetic flux density, and an insulation layer to minimize heat loss, optimized with specific thicknesses and materials like aluminum, copper, and ferrite to maximize energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a conventional heating layer design is used in cooking utensils for induction hobs, then the structure is simple and easy to manufacture, but energy efficiency is poor due to excessive eddy current losses and inefficient heat transfer

Engineering Contradiction:
Improveeddy current lossesVSAvoidlayer system complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies composite materials by creating a multi-layer bottom structure consisting of a heating layer (with high electrical conductivity ≥10^4 S/m and thermal conductivity ≥15 W/m/K), a magnetic layer (with relative permeability ≥10), and an insulation layer. This composite structure optimizes energy efficiency by minimizing eddy current losses in the heating layer while the magnetic layer enhances magnetic flux density, and the insulation layer reduces thermal losses to the induction hob.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by assigning different material properties to different layers: the heating layer has high electrical conductivity for efficient eddy current generation, the magnetic layer has high relative permeability for magnetic flux concentration, and the insulation layer has low thermal conductivity for heat retention. Each layer is optimized locally for its specific function within the overall system.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If the heating layer thickness is increased to reduce eddy current losses, then energy efficiency improves, but heat transfer to the cooking surface becomes less efficient

Engineering Contradiction:
Improveeddy current lossesVSAvoidheat transfer efficiency
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The patent applies parameter changes by optimizing the heating layer thickness to a specific range (5-20 μm) that balances two competing requirements: sufficient thickness to minimize eddy current losses and improve energy efficiency, while remaining thin enough to ensure efficient heat conduction to the cooking surface. The high thermal conductivity material (≥15 W/m/K) further enables effective heat transfer despite the thin thickness.

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If a magnetic layer with high relative permeability is added to increase magnetic flux density, then energy efficiency improves, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvepower losses in electronic unit and inductor coilVSAvoidmanufacturing complexity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies composite materials by integrating a magnetic layer with high relative permeability (≥10) into the bottom structure. This magnetic layer is positioned between the heating layer and the induction hob, where it concentrates and enhances the magnetic flux density, thereby reducing power losses in the electronic unit and inductor coil of the induction hob.

Inventive Principle:
Principle #40Composite materials

4Loss of energy

If high electrical conductivity materials are used in the heating layer to reduce eddy current losses, then energy efficiency improves, but thermal conductivity may be compromised

Engineering Contradiction:
Improveeddy current lossesVSAvoidthermal conductivity
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The patent applies parameter changes by specifying that the heating layer material must simultaneously satisfy both high electrical conductivity (≥10^4 S/m) to minimize eddy current losses and high thermal conductivity (≥15 W/m/K) to ensure efficient heat transfer. This dual parameter optimization resolves the contradiction between reducing electrical losses and maintaining thermal performance.

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 solution significantly increases energy efficiency by minimizing eddy current losses and ensuring uniform heat distribution, reducing power losses in the induction hob's electronic unit and inductor coil, while also providing thermal and electrical insulation to prevent overheating.

Implementation Method 1

A cooking utensil base (100) for a cooking utensil (200) for an induction hob (300), with a layer system (10) comprising at least one heating layer (12) which is designed to be heated by means of a current flow, in particular an eddy current flow

Methodology Applied
Scientific EffectEddy current heating: Eddy Currents

Implementation Method 2

the layer system (10) comprises at least one magnetic layer (14) with a relative permeability of at least 10, in particular at least 50, preferably at least 100 and particularly advantageously at least 500

Methodology Applied
Scientific EffectMagnetic flux concentration: Ferromagnetism

Implementation Method 3

the layer system should have at least one thermally conductive layer with a thermal conductivity of at least 15 W/m/K, in particular at least 50 W/m/K, preferably at least 100 W/m/K and particularly advantageously at least 200 W/m/K

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

an insulation layer with a thermal conductivity of at most 5 W/m/K, in particular of at most 1 W/m/K, advantageously of at most 0.1 W/m/K and in particular advantageously of a maximum of 0.01 W/m/K

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP2443974B1Cooking vessel bottom
Publication Date: 2019.06.19 BSH HAUSGERATE GMBH
  • EP2443974B1 patent drawingFigure 1~2

AI summary

The invention is based on a cooking utensil base with a layer system (10) which comprises at least one heating layer (12) with an electrical conductivity of at least 104 S/m. In order to provide a generic cooking utensil base with improved energy efficiency when heated on an induction hob, it is proposed that the heating layer be between 5 μm and 20 μm thick.