Gas Mixture Sensor and Ionization Sensor Check Method
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Solution Overview
Problem
Existing methods for controlling fuel gas-operated heaters, such as the SCOT process, become unreliable at low burner outputs due to sharp flame signal drops, leading to inaccurate combustion control.
Innovation Solution
A method that involves generating a gas mixture using actuators for gas and fuel gas, with a microthermal gas mixture sensor continuously monitoring and adjusting the mixture to match a target sensor signal, and an ionization sensor detecting flame signals to ensure stoichiometric combustion. The method temporarily changes the gas or fuel gas amounts to check sensor accuracy, comparing resulting changes in sensor signals to detect faulty functions and adjust control processes accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the SCOT method is used to control the gas-air mixture according to burner output, then the control system is simple to implement, but the flame signal drops sharply at low burner outputs making the control unreliable
Solution Approach 1:
The patent changes the control parameter from ionization current (which drops sharply at low outputs) to sensor signal that responds linearly across the entire burner output range. The sensor detects material properties of the gas mixture (thermal conductivity, thermal diffusivity, or speed of sound) which provide a reliable control signal even at low burner outputs, resolving the reliability issue while maintaining control system simplicity.
2Manufacturing precision
If the gas mixture is continuously adjusted using a microthermal gas mixture sensor, then the combustion control precision is improved, but the device complexity increases due to additional sensors and actuators
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a microthermal gas mixture sensor that uses physical property detection (thermal conductivity, thermal diffusivity, or speed of sound). This substitution achieves high combustion control precision through continuous material property measurement while actually reducing device complexity compared to traditional multi-sensor systems, as the sensor integrates multiple detection capabilities in a single device.
3Ease of operation
If the target ionization value is used for combustion control, then the control method is simple, but the control becomes inaccurate when fuel gas composition changes
Solution Approach 1:
The patent enables the control system to automatically adapt to fuel gas composition changes through self-calibration. The microthermal gas mixture sensor continuously monitors the material properties of the gas mixture, and the control unit automatically adjusts the target value based on detected changes in thermal conductivity, thermal diffusivity, or speed of sound. This self-adjusting mechanism maintains control simplicity while achieving high adaptability to different fuel gas compositions.
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 ensures accurate and reliable combustion control by detecting and correcting deviations in sensor signals, maintaining optimal combustion even at low burner outputs, and providing a means to diagnose and address sensor errors, thereby improving the overall efficiency and safety of the heater control process.
Implementation Method 1
The material property of the gas mixture detected by the microthermal gas mixture sensor is preferably its thermal conductivity, thermal diffusivity, or speed of sound
Implementation Method 2
The material property of the gas mixture detected by the microthermal gas mixture sensor is preferably its thermal conductivity, thermal diffusivity, or speed of sound
Implementation Method 3
Another possibility is to use at least one gas mass sensor based on the operating principle of ultrasonic measurement to determine the mass of the gas mixture and the specific speed of sound
Implementation Method 4
A flame signal is measured using an ionization sensor
Implementation Method 5
stoichiometric combustion is set in the heating appliance's burner. An ionization probe detects the burner's flame signal and the corresponding ionization current
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for checking a gas mixture sensor and ionization sensor with respect to their fault-free operation in a fuel-gas-powered heating device, wherein a gas mixture is produced by providing a quantity of gas via a first actuator (4, 107) and a quantity of fuel gas via a second actuator (3, 102) and mixing same, wherein the gas mixture sensor is positioned in the gas mixture for detecting a material property of the gas mixture (9, 105) and continuously transmits a sensor signal, which is dependent on the relevant gas mixture, to a control device (11, 100), wherein a flame signal is detected at a burner (109) of the heating device (200) via the ionization sensor, and an ionization signal is determined therefrom and transmitted to the control device (11, 100), wherein a corresponding ionization signal from the ionization sensor is assigned to the relevant sensor signal from the gas mixture sensor, and, for checking the gas mixture sensor and the ionization sensor, the gas quantity or the fuel gas quantity is temporarily changed in a predefined manipulated variable of the first or second actuator such that the gas mixture changes, and at the same time the resulting change in the sensor signal from the gas mixture sensor and in the ionization signal from the ionization sensor are measured and compared with one another.