Gas appliance and control method thereof
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Solution Overview
Problem
Conventional gas appliances face challenges in quickly detecting successful ignition and promptly interrupting fuel gas supply when a flame is extinguished, leading to potential safety hazards due to prolonged gas leakage and increased risk of accidental ignition.
Innovation Solution
A control method for a gas appliance that uses a thermocouple to generate detected voltages, where the gas valve remains open upon reaching a first voltage value indicating successful ignition and closes when the voltage falls below a second, higher value indicating flame extinguishment, thereby speeding up ignition detection and quickly stopping fuel gas supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thermocouple is used to detect flame and generate detected voltage, then the electromagnetic valve can be kept open after successful ignition, but the detected voltage increases gradually and takes a long time to reach the predetermined voltage value, causing delayed ignition detection
Solution Approach 1:
The patent applies preliminary action by using the igniter to preheat the thermocouple before actual ignition detection. The thermocouple is heated in advance during a preheating period, so when ignition occurs, the voltage generation response is significantly accelerated, reducing the detection time while ensuring reliable electromagnetic valve operation.
Solution Approach 2:
The patent implements periodic action through staged ignition detection periods. The ignition detection is divided into multiple stages: a preheating period where the thermocouple is heated, an ignition detection period where voltage is monitored, and a confirmation period. This periodic approach allows the system to balance fast detection with reliable verification of successful ignition.
2Reliability
If the thermocouple detects flame extinction by voltage drop, then the electromagnetic valve can close to prevent gas leakage, but the detected voltage decreases slowly and takes more than one minute to fall below the predetermined value, causing delayed gas shut-off
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the detected voltage during operation, not just during ignition. The system maintains the thermocouple in a ready state and continuously tracks voltage levels, enabling immediate detection of flame extinction events and rapid electromagnetic valve response to prevent gas leakage.
Solution Approach 2:
The patent implements feedback by continuously monitoring the detected voltage from the thermocouple and using this real-time information to control the electromagnetic valve. When the voltage drops below the predetermined threshold indicating flame extinction, the system immediately responds by closing the valve, creating a fast feedback loop that prioritizes safety over gradual response.
3Reliability
If the user keeps pressing the knob during ignition procedure, then the electromagnetic valve remains open for sufficient thermocouple heating, but the user cannot determine when to stop pressing based on clear indicators, causing operational inconvenience
Solution Approach 1:
The patent applies the color changes principle by using different display colors to indicate ignition status. The display shows different colors during the preheating period, successful ignition, and flame extinction states. This visual feedback provides clear indicators to users about when to release the knob, eliminating the need to rely on experience or guesswork.
Solution Approach 2:
The patent implements feedback by providing real-time visual information to the user through the display device. The system continuously communicates the current ignition state and expected duration to the user, enabling informed operation decisions rather than requiring users to press the knob for an indeterminate period based on experience.
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 method reduces ignition time, minimizes power consumption during ignition, and enhances safety by quickly interrupting fuel gas supply when a flame is accidentally extinguished, preventing prolonged leakage and potential hazards.
Implementation Method 1
The thermocouple 18 is adjacent to the burner 10, is electronically connected to the electromagnetic valve in the valve body 122, and is adapted to detect the flame to generate a detected voltage.
Data Source
AI summary
A gas appliance includes a burner, a gas valve, an igniter, a thermocouple, and a control device. The control device is adapted to execute a control method comprising the following steps: controlling the igniter to ignite and controlling the gas valve to open; receiving a detected voltage output from the thermocouple; controlling the igniter to stop igniting and keeping the gas valve open when the detected voltage reaches a first voltage value; receiving the detected voltage output from the thermocouple continuously, and controlling the gas valve to close the gas pipe when the detected voltage above a second voltage falls below the second voltage. The second voltage value is higher than the first voltage value. As such, an ignition procedure may be speeded up and the supply of the fuel gas may be interrupted more quickly when the flame is extinguished.