Thick-Layer Heating Element With Expansion Slots for Stable Contact

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Solution Overview

Problem

Current kitchen appliances with thick layer heating elements face issues such as poor heat transfer efficiency, thermal expansion mismatches, and difficulty in cleaning due to thick, conductive materials and moisture sensitivity, leading to uneven heating and reduced lifespan.

Innovation Solution

A planar substrate with a thick resistive layer and thermal expansion slots, where the substrate is made of stainless steel to ensure adhesion and energy distribution, and the resistive layer is protected from moisture, with deformable portions around electrical contact areas to accommodate thermal expansion and maintain uniform contact with the cooking wall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a thick layer heating element is pressed onto the cooking wall, then heat transfer efficiency is improved, but thermal expansion mismatch causes separation and reduces reliability

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidcontact stability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The heating element incorporates a deformable portion that can dynamically adjust its shape in response to thermal expansion, maintaining continuous contact with the cooking wall throughout heating and cooling cycles

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The heating element is designed with varying thickness, creating a deformable portion that can undergo dimensional changes during thermal cycling to accommodate expansion and contraction while maintaining contact pressure

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the cooking wall is made thick and conductive, then temperature uniformity is improved, but thermal inertia increases and efficiency decreases

Engineering Contradiction:
Improvetemperature uniformityVSAvoidheating efficiency
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The heating element features a deformable portion with localized flexibility that concentrates thermal energy transfer at the contact interface with the cooking wall, achieving uniform heating without requiring excessive wall thickness

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The heating element combines materials with different thermal and mechanical properties, creating a composite structure that provides both thermal conductivity for efficient transfer and mechanical compliance for maintaining contact

Inventive Principle:
Principle #40Composite materials

3Reliability

If mica sheet is used for insulation, then electrical insulation is improved, but moisture sensitivity reduces lifespan

Engineering Contradiction:
Improveelectrical insulationVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention replaces moisture-sensitive mica with a moisture-resistant alternative material that, while potentially less expensive, provides equivalent electrical insulation without the lifespan limitation imposed by moisture degradation

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The heating element uses a composite insulating material that combines electrical insulation properties with moisture resistance, eliminating the vulnerability to moisture that plagues traditional mica-based solutions

Inventive Principle:
Principle #40Composite materials

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 solution provides efficient heat transfer, low thermal inertia, and adaptability to different appliances, ensuring uniform heating and extending the lifespan of the heating element by managing thermal expansion and maintaining continuous contact with the cooking wall.

Implementation Method 1

at least one electrically resistive layer commonly called 'thick' layer in the technical field concerned

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

at least one heat expansion slot, said at least one slot defining deformable portions of the heating element

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

efficient heat transfer, low thermal inertia

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3056062B1Thick layer heating element and kitchen appliance comprising such a heating element
Publication Date: 2018.07.04 ILLINOIS TOOL WORKS INC
  • EP3056062B1 patent drawingFigure 1~2
  • EP3056062B1 patent drawingFigure 3~6
  • EP3056062B1 patent drawingFigure 7

AI summary

A thick layer heating element (10), in particular for heating a kitchen appliance (100), comprising a planar substrate (24) coated on one of its faces (28) with at least one electrically resistive track (26) which is linked to at least one area of electrical contact, characterized in that it comprises at least one thermal expansion slot (38), said at least one slot (38) defining deformable portions of the heating element, which each comprise a part of the resistive track (26) and which are distributed around said at least one area of electrical contact.