Device for heating and/or cooling a metal object
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Solution Overview
Problem
Existing induction cooktops face challenges in precisely measuring the temperature of the vessel, leading to inefficiencies in cooking and potential damage to the vessel due to excessive temperatures.
Innovation Solution
The device incorporates a distinct measuring sensor with a plurality of measuring coils connected in series, which magnetically couple to the metal portion of the vessel. This sensor supplies an alternating voltage at a predefined frequency to measure the resistance and/or inductance of the electrical circuit, allowing for precise temperature estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the heating coil is used as a temperature sensor, then the device complexity is reduced, but the measurement precision deteriorates and the heating uniformity is compromised due to timed control requirements
Solution Approach 1:
The patent divides the temperature sensing function from the heating function by introducing a separate measuring coil distinct from the heating coil. This segmentation allows each component to perform its dedicated function optimally - the heating coil for uniform heating and the measuring coil for precise temperature measurement without interference between the two functions
Solution Approach 2:
The patent introduces an intermediary measuring coil that magnetically couples to the vessel bottom to sense temperature. This intermediary component transfers temperature information from the vessel to the measurement circuit without requiring direct contact or interruption of the heating process, thereby maintaining both heating continuity and measurement accuracy
2Stability of the object's composition
If a measuring coil is positioned at the centre of the heating coil, then the heating uniformity is improved, but the measurement precision deteriorates due to insufficient accuracy in temperature detection
Solution Approach 1:
The patent employs parameter changes by utilizing the frequency-dependent electrical characteristics (impedance, inductance, resistance) of the measuring coil circuit. By measuring these electrical parameters at specific frequencies and comparing them against pre-stored reference values corresponding to different temperatures, the system achieves precise temperature detection through electrical parameter analysis rather than direct thermal measurement
3Measurement precision
If the voltage supplied to the heating coil is interrupted for temperature detection, then the measurement can be performed, but the productivity deteriorates due to discontinuous heating and increased time consumption
Solution Approach 1:
The patent implements periodic action by supplying the measuring coil with an alternating voltage at a predefined frequency during the temperature measurement process. This periodic electrical excitation enables continuous non-contact measurement of the vessel temperature without interrupting the DC or low-frequency heating process, allowing simultaneous heating and monitoring
Solution Approach 2:
The measuring coil acts as an intermediary that enables temperature measurement through magnetic coupling with the vessel bottom. This intermediary mechanism allows the system to obtain temperature data continuously without needing to interrupt the heating coil's power supply, thereby maintaining heating productivity while achieving measurement objectives
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 enables more precise temperature measurement of the metal object compared to prior art, reducing errors caused by non-uniform vessel materials or shapes, and allowing for improved cooking efficiency and vessel protection.
Implementation Method 1
The electromagnetic field generates induced currents in the ferromagnetic bottom portion of the vessel which produce heat due to the Joule effect
Implementation Method 2
The power supply supplies the heating coil with an alternating voltage having a frequency that is usually between 20 kHz and 70 kHz, in such a way that the heating coil generates a variable electromagnetic field
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Device (1) for heating a metal object, such as a vessel (2) having a metal portion, which comprises: a resting portion for supporting the metal object; heating means (5); a measuring sensor (8) for estimating a temperature of the metal object, comprising at least one measuring coil (9) and an electronic device (10). The measuring coil (9) is part of an electrical circuit. The electronic device (10) is connected to the electrical circuit to supply it with an alternating voltage at a predefined frequency that is between 100 kHz and 500 kHz and to measure a resistance of the electrical circuit supplied in this way.