Low Voltage DC Heating Device with RC Temperature Control
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Solution Overview
Problem
Existing heating devices, such as electric heating blankets, require high voltage electric current for effective heating, posing a risk of electric shock and are inconvenient to use outdoors or in vehicles, where alternative current may not be readily available.
Innovation Solution
A heating device using a microprocessor to control an RC circuit with an NTC element, where a duty cycle square wave is used to charge/discharge the circuit, allowing the device to operate with low voltage direct-current power and automatically adjust heating based on changing RC time constants to maintain a predetermined temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage electric current is used for heating, then heating effectiveness is improved, but safety risk of electric shock increases
Solution Approach 1:
The patent changes the voltage parameter from high voltage (100V+) to low voltage (12V DC), fundamentally altering the electrical operating conditions to eliminate electric shock hazards while maintaining heating effectiveness through optimized low-voltage heating elements and current control
2Power
If high voltage electric current is used for heating, then heating effectiveness is improved, but device complexity increases due to need for protective circuits and power inverters
Solution Approach 1:
The patent eliminates the need for power inverters and complex protective circuits by changing the operating voltage parameter to low voltage DC, which can be directly supplied by battery packs or DC power sources, thereby simplifying the overall device architecture
Solution Approach 2:
The patent extracts and removes the unnecessary components (power inverters, complex protective circuits) that are required only for high-voltage AC operation, resulting in a simplified device that operates efficiently on low-voltage DC
3Power
If power inverter is added to convert DC to AC for heating, then heating capability is improved, but device volume increases
Solution Approach 1:
The patent removes the power inverter component entirely by designing the heating system to operate natively on low-voltage DC, eliminating the volume occupation and weight of the inverter while maintaining full heating capability
Solution Approach 2:
The patent changes the electrical operating parameters from AC to DC and from high voltage to low voltage, allowing the use of compact DC-powered heating elements that do not require bulky power conversion equipment
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 safe and convenient heating with low voltage direct-current power, effectively controlling temperature within a predetermined range, reducing the risk of electric shock and improving usability in various environments.
Implementation Method 1
an RC circuit including an NTC (negative temperature coefficient) element can make an RC time constant change during the heating process because of the characteristic of the NTC element
Implementation Method 2
by heating of a direct-current electric power source
Data Source
AI summary
A heating device and its temperature control method, wherein an NTC element envelops a core member, a sensing wire is wound around an outside periphery of the NTC element for making parallel connection of the core member with the sensing wire; further, a capacitor, the sensing wire and an electric resistor are connected in series to form an RC circuit, the RC circuit is connected with a microprocessor and a switch. Thereby when the microprocessor outputs a control signal containing at least a duty cycle square wave in a predetermined time to control the switch to make a direct-current electric power source electrically charge/discharge for the RC circuit; meanwhile, the microprocessor measures RC time constant of the RC circuit, and when it detects changing of the RC time constant reaches a preset state, it outputs a control signal to make the heat emitting line and the direct-current electric power source in a state of circuit turning on or off, such that the heat emitting device is kept at a predetermined working temperature.