Induction Heating Coil Structure for Thermal Expansion Stability

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Solution Overview

Problem

Existing induction cooking devices face limitations in mechanical stability and efficiency due to thermal expansion issues and the risk of electrical short circuits, particularly with enamel-insulated induction heating lines that operate at low temperatures.

Innovation Solution

The design incorporates induction heating line elements wound azimuthally and radially, with sections made predominantly of metal edge material to compensate for thermal expansion and reduce the likelihood of short circuits, allowing for higher operating temperatures and improved mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If enamel insulation is used in induction heating line elements, then electrical insulation is provided, but the operating temperature is limited to maximum 200°C

Engineering Contradiction:
Improveoperating temperatureVSAvoidelectrical insulation reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent removes the enamel insulation layer from the induction heating line elements, extracting the limiting factor that constrained operating temperature. By eliminating this insulation material, the heating elements can operate at temperatures exceeding 200°C without risking insulation breakdown or electrical short circuits.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an air gap as an intermediary between adjacent induction heating line elements. This air space serves as the electrical insulation medium, replacing the enamel coating while allowing high-temperature operation. The air gap effectively mediates between the need for electrical isolation and the requirement for high operating temperatures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If conventional winding methods are used, then assembly is simple, but thermal expansion causes mechanical instability

Engineering Contradiction:
Improvemechanical stabilityVSAvoidwinding structure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent implements azimuthal and radial winding patterns that create localized structural characteristics throughout the coil. This non-uniform local arrangement of wire segments compensates for thermal expansion effects in different directions, maintaining overall mechanical stability while preserving relatively simple conventional winding processes.

Inventive Principle:
Principle #3Local quality

3Reliability

If edge regions are made of metal material, then thermal expansion is compensated and short circuit risk is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveshort circuit preventionVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent makes the entire induction heating line element consist of metal material, giving it multiple functions simultaneously: it provides structural integrity, compensates for thermal expansion, and eliminates the need for separate insulation components. This universal metal construction prevents short circuits through proper spacing while simplifying manufacturing by using a single material type throughout.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enhances mechanical stability, reduces electrical short circuit risks, and enables efficient heating with higher operating temperatures, leading to improved performance and cost-effectiveness compared to conventional designs.

Implementation Method 1

Each of the induction heating cable elements has a core material formed from a metal and, in an operating state, provides an alternating electromagnetic field

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Due to the azimuthal and radial winding of the induction heating cable elements in the longitudinal direction of the induction heating cable, thermal expansion of the induction heating cable elements in the longitudinal direction of the induction heating cable elements can be at least partially compensated

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3811732B1Induction cooking device
Publication Date: 2024.02.14 BSH HAUSGERATE GMBH
  • EP3811732B1 patent drawingFigure 1~2
  • EP3811732B1 patent drawingFigure 3~4
  • EP3811732B1 patent drawingFigure 5

AI summary

The invention relates to an induction cooking device (10a-b), in particular an induction oven device, comprising at least one induction heating unit (12a-b), which has at least one induction heating line (14a-b) with a plurality of induction heating line elements (16a-b) that are wound in the longitudinal direction (18a-b) of the induction heating line (14a-b) in an azimuthal and radial manner. The aim of the invention is to provide a generic device with improved properties with respect to its structure. This is achieved in that at least the majority of at least one of the induction heating line elements (16a-b) consists at least partly of at least one edge material that has at least one metal in at least one edge region (20a-b) of the induction heating line element (16a-b).