Cooking apparatus
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Solution Overview
Problem
Conventional cooking apparatuses face challenges in accurately detecting the temperature of cooking utensils without damaging temperature sensors, which are expensive and occupy significant space, and require additional cooling due to high temperatures.
Innovation Solution
A cooking apparatus that uses a working coil, an inverter with switching elements, a phase detector, and a controller to calculate the temperature of a target object by detecting the phase difference between the resonant current and voltage, allowing for precise temperature measurement without a separate temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to detect the temperature of the cooking utensil, then the temperature can be measured, but the temperature sensor is expensive and occupies a large volume of space
Solution Approach 1:
The cooking apparatus uses its own working coil and circuit parameters to detect temperature, rather than requiring an external temperature sensor. The system serves itself by monitoring changes in the working coil's impedance and resonant frequency, which naturally vary with temperature, thereby eliminating the need for separate sensing components.
Solution Approach 2:
The patent replaces the physical temperature sensor (mechanical/thermal contact method) with an electrical measurement method. By measuring the phase difference between voltage and current in the working coil, the system indirectly determines temperature without physical contact, thus avoiding the need for expensive and space-consuming temperature sensors.
2Measurement precision
If the temperature sensor is disposed near the cooking utensil to accurately detect temperature, then the temperature measurement accuracy is improved, but the temperature sensor is highly prone to damage due to high temperature
Solution Approach 1:
The patent introduces the working coil's electrical parameters (impedance, resonant frequency, phase difference) as an intermediary to measure temperature. Instead of placing a temperature sensor directly near the hot cooking utensil, the system uses the working coil's electrical characteristics, which change predictably with temperature, to indirectly determine the temperature without exposing any sensor to high heat.
Solution Approach 2:
The system creates an electrical copy or model of the thermal state by measuring the working coil's impedance and resonant frequency changes. These electrical parameters serve as a proxy for temperature, allowing the controller to determine the cooking utensil's temperature without any physical sensor being exposed to the high-temperature environment.
3Reliability
If a separate cooling device is added to protect the temperature sensor from high temperature damage, then the temperature sensor reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature sensing function from the main cooking system and integrates it into the control circuitry by monitoring the working coil's electrical parameters. By taking out the need for a separate temperature sensor and its associated cooling protection, the system simplifies the overall design while maintaining temperature detection capability through phase difference measurement of the working coil.
4Measurement precision
If conventional temperature sensors are used, then temperature can be detected, but the temperature sensor occupies a large volume of space within the cooking apparatus
Solution Approach 1:
The working coil serves multiple functions: it generates the magnetic field for induction heating and simultaneously acts as a temperature sensor through its impedance and resonant frequency characteristics. This multi-functionality eliminates the need for separate temperature sensing components, thereby reducing the overall space required in the cooking apparatus.
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
Enables accurate temperature detection of cooking utensils without the need for additional sensors, reducing costs and improving reliability by using the apparatus's existing components to calculate temperature based on phase differences, thus enhancing user safety and satisfaction.
Implementation Method 1
an induction range that uses an electromagnetic field for heating by electromagnetic induction
Implementation Method 2
an eddy current is formed in the cooking utensil, and heat is generated by the eddy current flowing in the cooking utensil
Implementation Method 3
a phase detector configured to detect a phase difference between the resonant current and a voltage applied to an output terminal of the inverter
Data Source
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AI summary
A cooking apparatus includes: a working coil, an inverter including a plurality of switching elements and configured to apply, by operating the plurality of switching elements, a resonant current of a predetermined frequency to the working coil, a phase detector configured to detect a phase difference between the resonant current and a voltage applied to an output terminal of the inverter, and a controller configured to calculate, based on the detected phase difference, a temperature of a target object that is placed above the working coil.