Induction Hob Temperature Sensing with Magnetic Field Shielding
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Solution Overview
Problem
Existing cooking devices with automatic functions face challenges in accurately detecting cooking parameters, particularly temperature, especially when using different cookware materials like copper and stainless steel, leading to issues with reproducibility and accuracy, and existing solutions either restrict user movement or can be accidentally covered by other objects.
Innovation Solution
A cooking device with a sensor system that includes a magnetic shielding device to prevent interfering magnetic fields, an optical shielding device for thermal radiation, and a thermal compensation system, allowing for precise non-contact temperature measurement of cooking vessels without overheating the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is integrated in the cooking container, then temperature detection is possible, but the user cannot use previous cookware and the sensor may be accidentally eaten
Solution Approach 1:
The patent introduces an intermediary solution by placing a temperature sensor in the hob plate rather than in the cooking container. This intermediate position allows the sensor to detect temperature through the bottom of the container without being in direct contact with the food or requiring modification of the cookware, thus maintaining cookware compatibility while achieving temperature detection
Solution Approach 2:
The patent replaces direct mechanical contact sensing (inserting a sensor into the container or food) with non-contact or indirect sensing through the hob plate. This substitution eliminates the need for modified cookware and prevents the sensor from being accidentally eaten while still enabling accurate temperature measurement
2Measurement precision
If a hob sensor is arranged above the hob to determine temperature without contact, then temperature detection is possible, but other objects must not stand in the way and user freedom of movement is restricted
Solution Approach 1:
The patent inverts the conventional approach by placing the temperature sensor below the hob plate instead of above it. This inverted arrangement allows the sensor to detect temperature through the bottom of the cooking container without protruding into the cooking space, thereby eliminating obstacles for user movement and object placement while maintaining temperature detection capability
3Ease of operation
If a thermal sensor below the hob plate is used to detect thermal radiation, then user freedom of movement is not restricted, but measurement accuracy and reproducibility are insufficient for automatic functions
Solution Approach 1:
The patent converts the harmful magnetic fields generated by the induction heating device into a beneficial shielding mechanism. By introducing magnetic shielding elements, the system directs and contains the magnetic fields in a controlled manner, preventing them from interfering with the temperature sensor while allowing the sensor to accurately detect thermal radiation from the cooking container
Solution Approach 2:
The patent introduces magnetic shielding elements as intermediaries between the induction heating device and the temperature sensor. These shielding elements act as a buffer that manages the interaction between magnetic fields and the sensor, protecting the sensor from field interference while allowing thermal radiation detection to proceed accurately
4Device complexity
If no magnetic shielding is provided, then the device structure is simpler, but interfering magnetic fields reduce measurement accuracy and reproducibility
Solution Approach 1:
The patent transforms the harmful magnetic field interference into a manageable aspect of the system by introducing magnetic shielding elements. These elements convert the chaotic interfering fields into a controlled magnetic environment, improving measurement accuracy while adding only minimal structural complexity
Solution Approach 2:
The patent modifies the magnetic field parameters in the sensor region by introducing shielding elements with specific magnetic properties. This changes the magnetic field distribution and intensity in the vicinity of the sensor, creating optimal conditions for accurate temperature detection while maintaining overall system simplicity
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 solution significantly enhances measurement accuracy and reproducibility by shielding electromagnetic interactions and thermal radiation, ensuring reliable detection of cooking parameters across various cookware materials, improving user safety and convenience.
Implementation Method 1
WO 2008/148 529 A1 provides a thermal sensor below the hob plate, which detects thermal radiation and uses this to determine a temperature
Implementation Method 2
The sensor device has at least one magnetic shielding device. The magnetic shielding device is designed and suitable in particular for shielding from electromagnetic interactions and in particular for shielding from the electromagnetic field of the induction device
Data Source
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AI summary
The cooking device (1) has a cooking area (11) provided with a cooking point (21). A heating device (2) is provided for heating a cooking region (31). A sensor device (3) is provided for detecting a physical variable for the detection of the state of the cooking region. The sensor device is provided with magnetic shielding equipment which is provided for shielding of the electromagnetic field of an induction unit (12). An independent claim is included for a method for operating a cooking device.