Food preparation device with PTC resistors in parallel
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Solution Overview
Problem
Existing food preparation devices often lead to local overheating during cooking, resulting in delayed cooking processes and uneven heat distribution, which can cause food to burn or be undercooked.
Innovation Solution
A food preparation device with electrical PTC conductors connected in parallel, where each conductor is connected via bridges, allowing for automatic redistribution of electrical current based on temperature differences, ensuring even heat distribution without additional control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single heating element is used, then the device complexity is low, but local overheating occurs and heat distribution is uneven
Solution Approach 1:
The heating device is segmented into multiple PTC thermistor elements (at least two) connected in parallel, each capable of independent heat generation. This segmentation allows different regions to be heated independently, preventing local overheating while maintaining relatively simple overall device structure.
Solution Approach 2:
Each PTC thermistor element provides localized heating with self-regulating temperature control through its positive temperature coefficient特性. The parallel connection allows current to automatically redistribute to cooler regions, ensuring each local area maintains appropriate temperature quality without requiring complex centralized control.
2Temperature
If heating continues until thermal equilibrium is reached, then even heat distribution is achieved, but cooking time is delayed
Solution Approach 1:
The PTC thermistors provide inherent negative feedback through their positive temperature coefficient特性 - as temperature increases, resistance increases, automatically reducing current and heat generation in already-hot regions. This self-regulating feedback mechanism rapidly achieves thermal equilibrium without requiring external control systems or delaying the cooking process.
Solution Approach 2:
The parallel-connected PTC thermistors dynamically adjust their resistance and current distribution in real-time based on temperature differences. This dynamic response allows the system to quickly adapt to changing thermal conditions and achieve uniform heat distribution faster than static heating systems, reducing overall cooking time.
3Reliability
If PTC thermistors are connected in parallel with electrical bridges, then current redistributes automatically to prevent overheating, but the electrical circuit becomes more complex
Solution Approach 1:
The parallel-connected PTC thermistors with electrical bridges create a self-regulating circuit where current automatically redistributes based on temperature-induced resistance changes. Each thermistor serves itself by adjusting its own resistance, and the electrical bridges facilitate automatic current routing without requiring external control systems, sensors, or complex circuitry.
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 prevents overheating, ensures uniform temperature distribution, and reduces cooking time by dynamically adjusting heat generation to colder areas, thereby achieving quick and reliable cooking results without additional components or technical effort.
Implementation Method 1
electrical PTC thermistors for heating a food in a food preparation space
Implementation Method 2
A PTC thermistor according to the present invention has a positive temperature coefficient. This means that the electrical resistance of the PTC thermistor increases with increasing temperature.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a food preparation appliance 1 with an electric heating element comprising at least two electrical thermistors 5, 6, 7, 8 for heating food in a food preparation chamber, wherein the electrical thermistors 5, 6, 7, 8 are connected in parallel. The parallel-connected thermistors 5, 6, 7, 8 are electrically connected to one another by one or more electrical bridges 11 to 17. The invention prevents localized heating during food preparation.