Induction Cooktop Temperature Sensing Despite Panel Dirt
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cooktop control methods inaccurately determine the temperature of cooking utensils due to variations in the emissivity of the utensil's bottom and the transmittance of the cooktop panel, especially when the panel becomes dirty, leading to errors in heat output control.
Innovation Solution
A method that includes heat sensor units beneath the cooktop panel to measure heat flow, a light source for emissivity determination via reflection measurement, and an auxiliary heater to maintain a desired temperature, allowing for accurate calculation of the utensil's temperature by accounting for emissivity and transmittance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reflection measurement is performed to determine emissivity of the cooking utensil bottom, then temperature measurement accuracy is improved, but measurement errors occur when the cooktop panel becomes dirty
Solution Approach 1:
The patent introduces an auxiliary heater as an intermediary device that heats the cooktop panel to a predetermined temperature before performing reflection measurements. This intermediary heating step ensures consistent thermal conditions during measurement, compensating for the variable transmittance caused by dirt accumulation on the panel surface.
Solution Approach 2:
The patent applies preliminary action by pre-heating the cooktop panel to a predetermined temperature before conducting the reflection measurement to determine emissivity. This preliminary thermal conditioning ensures that the panel is in a known thermal state, which improves the reliability of subsequent temperature measurements even when the panel is dirty.
2Device complexity
If the cooktop panel transmittance varies due to dirt accumulation, then temperature determination accuracy deteriorates, but the basic measurement system remains simple
Solution Approach 1:
The patent implements feedback by measuring the actual temperature of the cooktop panel using a heat sensor unit and using this information to correct the temperature determination of the cooking utensil. The control system continuously monitors panel temperature and adjusts the calculation of utensil temperature based on the measured panel conditions, compensating for dirt-related transmittance variations.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the measurement approach based on the thermal state of the cooktop panel. By heating the panel to a predetermined temperature and using this known thermal parameter as a reference, the system compensates for variable transmittance conditions caused by dirt accumulation.
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 approach provides improved accuracy in determining the actual temperature of the cooking utensil's bottom, enabling precise control of the induction heating device and reducing errors caused by dirt accumulation on the cooktop panel.
Implementation Method 1
at least one cooking zone (2) which can be heated by an induction heating device (3)
Implementation Method 2
the first heat sensor unit (4.1) measures a heat flow emanating downward substantially only from the cooktop panel (1)
Implementation Method 3
further including a light source for performing a reflection measurement to determine an emissivity
Data Source
AI summary
A method and cooktop include a cooktop panel, a cooking zone, and an induction heating device disposed below the cooktop panel. First, second and third heat sensor units are disposed beneath the cooktop panel in a region of a measuring spot. The first heat sensor unit is configured to measure heat flow from substantially only the cooktop panel. The second and third heat sensor units are configured to measure heat flow from the cooktop panel and a cooking utensil disposed thereon. A light source is provided for measuring an emissivity of the bottom of the cooking utensil. An auxiliary heater heats the region of the measuring spot. An electrical control system calculates a ratio from signals of the second and third heat sensor units and determines an actual temperature of the bottom of the cooking utensil from the ratio by using a temperature of a lower surface of the cooktop panel measured by the first sensor unit and a value of the emissivity of the cooking utensil bottom.