Bi-Metallic Susceptor Cookware for Self-Regulating Induction Heating
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Solution Overview
Problem
Induction heating systems face challenges with overheating, underheating, and uneven heating due to the high Curie temperature of ferromagnetic materials, which require complex control systems and significant operator interaction, while non-ferromagnetic materials like copper and aluminum are not effectively heated by induction coils.
Innovation Solution
A bi-metallic assembly in cookware with a magnetic susceptor layer and a non-magnetic base layer, where the susceptor layer is magnetic at room temperature and becomes non-magnetic at a Curie temperature, and the base layer is an electrical and thermal conductor, allowing for controlled heating and even temperature distribution across the cooking surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrous materials are used in induction cookware, then magnetic coupling with induction coil is achieved, but overheating occurs due to high Curie temperature
Solution Approach 1:
The patent applies composite materials by combining a ferrous susceptor layer with a non-ferrous base layer (copper, aluminum, or copper-nickel alloy). This composite structure enables magnetic coupling through the ferrous layer while the non-ferrous base layer provides superior thermal conduction and lower operating temperature, resolving the contradiction between achieving magnetic coupling and preventing overheating.
2Temperature
If non-ferrous materials like copper and aluminum are used, then thermal conduction is improved, but magnetic coupling with induction coil is lost
Solution Approach 1:
The patent segments the cookware into two distinct functional layers: a ferrous susceptor layer that provides magnetic coupling with the induction coil, and a non-ferrous base layer that provides superior thermal conduction. This segmentation allows each material to perform its optimal function without compromising the other, resolving the contradiction between thermal conduction efficiency and magnetic coupling effectiveness.
3Productivity
If ferrous materials are used in induction cookware, then induction heating is enabled, but complex control systems are required to prevent overheating
Solution Approach 1:
The patent enables self-service by designing the bi-metallic structure to inherently self-regulate temperature through the Curie effect. When the ferrous susceptor layer reaches its Curie temperature, it loses magnetic properties and stops generating heat, automatically preventing overheating without requiring complex external control systems or operator intervention.
4Temperature
If ferrous materials are used in induction cookware, then heating is achieved, but uneven heating and significant operator interaction are required
Solution Approach 1:
The bi-metallic structure provides self-service temperature regulation where the ferrous susceptor layer automatically stops heating at its Curie temperature by losing magnetic properties. This self-regulating mechanism eliminates the need for continuous operator monitoring and interaction, significantly improving ease of operation while maintaining effective heating capability.
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 bi-metallic assembly enables more even heating across the cooking surface, reduces overheating, and allows for lower Curie temperatures compatible with food preparation, maintaining optimal cooking temperatures without requiring expensive induction cooktop replacements.
Implementation Method 1
The variable electromagnetic field induces an electromagnetic field in the container, which causes eddy currents within the container that results in heating of the susceptor
Implementation Method 2
The variable electromagnetic field induces an electromagnetic field in the container, which causes eddy currents within the container that results in heating of the susceptor
Implementation Method 3
Induction heating systems employ an electromagnetic field to generate heat
Implementation Method 4
The susceptor layer is magnetic at room temperature and has a Curie temperature at which the susceptor layer is non-magnetic
Implementation Method 5
The base layer is non-magnetic at the room temperature, an electrical conductor, a thermal conductor, and in thermal communication with the susceptor layer
Data Source
AI summary
Cookware, and an induction cooking system including the cookware, include a container, a base layer, and a susceptor layer. The container and the base layer are non-magnetic at room temperature, while the susceptor layer is magnetic at room temperature and has a Curie temperature at which the susceptor layer becomes non-magnetic. During heating of a material within the container, the base layer functions as a passive heat exchange to transfer heat across the susceptor layer. Further, during the heating, the base layer conducts an electric current when the susceptor layer approaches a leveling temperature and/or the Curie temperature of the susceptor layer, thereby decreasing an amount of heat produced and resulting in a more even heating of the material.