Thick layer heating element and kitchen appliance comprising such a heating element
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Solution Overview
Problem
Current heating elements in kitchen appliances suffer from inefficiencies such as poor heat transfer, high inertia, and susceptibility to moisture, leading to non-uniform heating and reduced lifespan due to differential thermal expansions and the use of sensitive materials like mica.
Innovation Solution
A thick layer heating element with a planar substrate coated with a resistive layer, featuring thermal expansion slots and a metallic substrate to ensure adhesion and efficient heat distribution, along with a protective insulating layer to prevent moisture exposure, allowing for uniform and adaptable heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a thick cooking wall is used to ensure good temperature uniformity, then temperature uniformity is improved, but thermal inertia increases
Solution Approach 1:
The heating system is segmented into distinct functional layers: a thin cooking wall for rapid thermal response, a thermal interface layer for heat distribution, and a heating element for energy conversion. This segmentation allows each component to perform its function optimally without the drawbacks of a thick monolithic structure.
Solution Approach 2:
The system uses composite material structures including a multilayer heating element with substrate, resistive layer, and protective coating, combined with a thermal interface material between the cooking wall and heating element. This composite approach achieves both rapid response and uniform heat distribution.
2Loss of energy
If shielded resistors are used in direct contact with oil for efficient heating, then heating efficiency is improved, but cleaning difficulty increases
Solution Approach 1:
The heating element is extracted from direct contact with the cooking medium (oil or food). The resistive heating layer is positioned on the opposite side of the thin cooking wall, eliminating the need for post-heating cleaning while maintaining efficient heat transfer through the wall.
Solution Approach 2:
The thin cooking wall acts as an intermediary between the heating element and the cooking medium. It efficiently conducts heat from the resistors to the food or oil while preventing direct contact, thus solving both the efficiency and cleaning issues.
3Force
If pressure plate is used to hold heating element against cooking wall, then contact pressure is improved, but gap formation due to thermal expansion increases
Solution Approach 1:
The design explicitly accounts for thermal expansion by selecting materials with compatible expansion coefficients and providing expansion compensation mechanisms. The flexible mounting structure allows the heating element to expand and contract with temperature changes while maintaining consistent contact pressure.
Solution Approach 2:
The mounting system transitions from a rigid fixed-position structure to a dynamic flexible structure that can adapt to thermal expansion. The flexible mounting maintains optimal contact pressure across varying temperature conditions, preventing gap formation.
4Strength
If thick substrate is used for heating element to ensure structural stability, then mechanical strength is improved, but heat transfer efficiency decreases
Solution Approach 1:
The substrate thickness is optimized to a thin profile that balances mechanical strength with thermal conductivity. The thickness parameter is specifically selected to minimize thermal resistance while maintaining sufficient structural integrity for handling and installation.
Solution Approach 2:
The heating element uses composite construction where the thin substrate is reinforced with structural support elements or coated with high-strength materials. This allows the substrate to remain thin for efficient heat transfer while composite reinforcement provides the necessary mechanical strength.
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 optimal energy transmission, low thermal inertia, and uniform temperature regulation, ensuring efficient and durable heating performance across various kitchen appliances.
Implementation Method 1
a planar substrate coated on one of its faces with at least one electrically resistive layer commonly called 'thick' layer in the technical field concerned
Implementation Method 2
this layer being linked to at least one electrical contact area
Data Source
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.