Ironing Chest Multilayer Structure for Uniform Induction Heating

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Solution Overview

Problem

Existing professional chest ironers using electromagnetic induction heating face challenges in finding materials with high magnetic permeability that are flexible enough to match the shape of the drum and avoid hot or cold spots, while being cost-effective for industrial application.

Innovation Solution

A multilayer structure for the ironing chest comprising a diamagnetic or paramagnetic metal material with high thermal conductivity for the supporting sheet and a ferromagnetic layer with lower thermal conductivity, applied via cold-spray deposition, along with a protective coating, to achieve efficient heating and flexibility, and a steam-permeable outer surface for the ironing drum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a material with high magnetic permeability is used in the ironing chest for electromagnetic induction heating, then heating efficiency is improved, but the material becomes too rigid to match the shape of the drum and may cause hot or cold spots

Engineering Contradiction:
Improveheating efficiencyVSAvoidflexibility to match drum shape
Core Design Contradiction:
Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The ironing chest is constructed as a composite structure with a flexible base layer (such as rubber or polymer) that can conform to the drum shape, combined with a ferromagnetic layer (such as iron powder or ferrite particles) dispersed within or applied on the base layer. This composite structure provides both the flexibility needed to match the drum contour and the magnetic properties required for effective electromagnetic induction heating, eliminating hot and cold spots while maintaining adaptability.

Inventive Principle:
Principle #40Composite materials

2Use of energy by moving object

If a material with high magnetic permeability is used in the ironing chest, then electromagnetic induction heating effectiveness is improved, but the cost of the material increases making industrial application less viable

Engineering Contradiction:
Improveelectromagnetic induction heating effectivenessVSAvoidcost-effectiveness for industrial application
Core Design Contradiction:
Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

Instead of using expensive high magnetic permeability material throughout the entire ironing chest, the invention applies ferromagnetic particles or powder only in specific regions where heating is most needed, or uses a lower concentration of magnetic material in areas with lower heating requirements. This localized approach maintains heating effectiveness while significantly reducing material costs and making the solution more viable for industrial application.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the physical state or form of the magnetic material from solid blocks or sheets to fine particles or powder that can be dispersed in a flexible matrix. This parameter change allows the use of cheaper ferromagnetic materials (like iron powder or common ferrites) instead of expensive high-permeability alloys, while still achieving effective electromagnetic induction heating through the distributed particle structure.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If electromagnetic induction heating is used to heat the ironing chest quickly, then productivity is improved, but it requires specialized materials that are difficult to source and apply

Engineering Contradiction:
Improveheating speedVSAvoidmaterial availability and application
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The invention changes the magnetic properties of the ironing chest material by incorporating ferromagnetic particles or powder into a flexible base material. This parameter change enables the material to respond effectively to electromagnetic induction heating, achieving rapid heating speeds comparable to specialized materials, while using readily available components that are easy to source and apply in industrial manufacturing.

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 ensures uniform temperature distribution, improved flexibility to match the drum shape, and cost-effective production, enhancing the ironing process by maintaining high-frequency Eddy currents for efficient heating without hot spots.

Implementation Method 1

an electric power unit that circulates along the electrical conductor an alternating current with a frequency preferably ranging between 20.000 Hz to 40.000 Hz, so that the induction coils generate a high-frequency electromagnetic field that affects the ironing chest. This high-frequency electromagnetic field, in turn, generates into the body of the ironing chest, via electromagnetic induction, high-frequency Eddy currents

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

generates into the body of the ironing chest, via electromagnetic induction, high-frequency Eddy currents (also called Foucault currents) that quickly heat up the whole ironing chest via Joule heating

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

a ferromagnetic layer with lower thermal conductivity, applied via cold-spray deposition

Methodology Applied
Scientific EffectCold-spray deposition: Deposition (physical)

Implementation Method 4

a diamagnetic or paramagnetic metal material with high thermal conductivity for the supporting sheet

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 5

a steam-permeable outer surface for the ironing drum

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentEP3412825B1Ironing machine
Publication Date: 2020.07.01 ELECTROLUX LAUNDRY SYST FRANCE
  • EP3412825B1 patent drawingFigure 1~2
  • EP3412825B1 patent drawingFigure 3~4
  • EP3412825B1 patent drawingFigure 5~6

AI summary

A ironing machine (1) comprising: an axially-rotatable ironing drum (4); a motor assembly adapted to drive the ironing drum (4) into rotation about the drum longitudinal axis (A); an ironing chest (7) which is arranged adjacent to the ironing drum (4), locally substantially parallel to the peripheral surface (4p) of said ironing drum (4); a supporting assembly (9) adapted to keep the ironing drum (4) and the ironing chest (7) adjacent to one another; and an induction device (10) which is located adjacent to the ironing chest (7) and is adapted to heat up, via electromagnetic induction, the ironing chest (7); said ironing chest (7) comprising a platelike member (13) which extends beside the ironing drum (4), is substantially C-bent so as to extend locally substantially parallel to the peripheral surface (4p) of said ironing drum (4), and has a multilayer structure that includes: a main supporting sheet (14) which is substantially C-bent and is made of a metal material having a given thermal conductivity; and a ferromagnetic layer (15) which covers the convex face of said main supporting sheet (14), and is made of a ferromagnetic metal material having a thermal conductivity lower than that of the metal material forming said main supporting sheet (14).