Ferrite Disk Recess for Induction Hob Heat Homogeneity

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Solution Overview

Problem

Existing induction heating devices for induction hobs result in inhomogeneous heating of cookware due to 'hot rings' caused by non-uniform magnetic field focusing, leading to uneven power density distribution.

Innovation Solution

A ferrite disk with a recess is used to modify the magnetic field focusing over the induction heating coil, reducing power density maxima and achieving a more even heat distribution by altering the geometry of the ferrite arrangement, specifically with a reduced wall thickness in the recess area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a ferrite arrangement with constant wall thickness is used for magnetic field focusing, then the magnetic field is focused over the induction heating coil, but hot rings form with significantly higher power density compared to neighboring areas

Engineering Contradiction:
Improvepower density distributionVSAvoidhomogeneity of heat distribution
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

The ferrite arrangement features variable wall thickness with different thicknesses in different regions (first region vs second region). This local variation in geometry creates different magnetic field focusing characteristics in different areas, specifically reducing the power density maxima in the first region while maintaining adequate focusing in the second region, thereby achieving more homogeneous heat distribution across the cookware surface.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the geometric parameter (wall thickness) of the ferrite arrangement from constant to variable. By modifying the wall thickness parameter across different regions of the ferrite arrangement, the magnetic field distribution and resulting power density are optimized to eliminate hot rings while maintaining overall heating effectiveness.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the ferrite arrangement has variable wall thickness, then power density maxima are reduced and heat distribution is homogenized, but the manufacturing complexity increases

Engineering Contradiction:
Improvehomogeneity of heat distributionVSAvoidferrite arrangement geometry
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The ferrite arrangement features variable wall thickness with different thicknesses in different regions (first region vs second region). This local variation in geometry creates different magnetic field focusing characteristics in different areas, specifically reducing the power density maxima in the first region while maintaining adequate focusing in the second region, thereby achieving more homogeneous heat distribution across the cookware surface.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the geometric parameter (wall thickness) of the ferrite arrangement from constant to variable. By modifying the wall thickness parameter across different regions of the ferrite arrangement, the magnetic field distribution and resulting power density are optimized to eliminate hot rings while maintaining overall heating effectiveness.

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

This design ensures a homogeneous current and heat distribution across the cookware surface, reducing disruptive power density maxima and enhancing cooking performance by allowing adjustable temperature settings and locations.

Implementation Method 1

an induction heating coil (1) for generating a magnetic field

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a base (40) of the cookware made of a ferromagnetic material into which a current or power density is induced

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

a base (40) of the cookware made of a ferromagnetic material into which a current or power density is induced

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 4

a ferrite arrangement (2) for focusing a magnetic field generated by the induction heating coil (1)

Methodology Applied
Scientific EffectMagnetic field focusing: Magnetic Field

Implementation Method 5

a ferrite arrangement (2) for focusing a magnetic field

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP4255114A1Induction heating device and induction hob assembly
Publication Date: 2023.10.04 HOCHSCHULE BIELEFELD UNIV OF APPL SCI & ARTS
  • EP4255114A1 patent drawingFigure 1~2
  • EP4255114A1 patent drawingFigure 3~4
  • EP4255114A1 patent drawingFigure 5~6

AI summary

The invention relates to an induction heating device for an induction hob with an induction heating coil, with a ferrite arrangement for focusing a magnetic field generated by the induction heating coil and with a support unit for supporting the induction heating coil and/or the ferrite arrangement, wherein the ferrite arrangement is designed as a ferrite disk covering the induction heating coil and having a recess.