Heating Device Ionization Electrode Recalibration
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Solution Overview
Problem
Existing methods for recalibrating combustion control systems in heaters require significant effort and can lead to temporary carbon monoxide production and electrode damage due to the need to operate at suboptimal lambda values during calibration.
Innovation Solution
A method utilizing a second ionization signal from an ignition electrode to correct the calibration data of the first ionization signal, allowing for recalibration without moving the combustion to lambda = 1, using a second measuring system that measures ionization signals independently to detect and correct for changes in the ionization electrode and its electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If recalibration is performed using conventional methods that operate at lambda values of 1 or below, then recalibration can be completed, but carbon monoxide is temporarily produced and flame temperatures become excessively high which can damage the ionization electrode
Solution Approach 1:
The patent uses a second ionization electrode as an intermediary measuring device to obtain reference measurements during recalibration. This mediator allows the system to perform calibration without requiring the primary ionization electrode to operate in harmful conditions, as the second electrode provides alternative measurement data for comparison and calibration correction.
Solution Approach 2:
The patent changes the operational parameters during recalibration by maintaining lambda values above 1 (specifically lambda > 1.1), avoiding the dangerous range of lambda = 1 or below. This parameter change ensures that flame temperatures remain controlled and carbon monoxide production is minimized while still enabling calibration through comparison with the second electrode's measurements.
2Measurement precision
If a second ionization electrode is installed for mutual calibration, then calibration drift can be detected, but installation effort and device complexity increase
Solution Approach 1:
The patent makes the second ionization electrode multi-functional by using it both for flame monitoring (its original function) and for recalibration purposes (new function). This universal use of the second electrode eliminates the need for additional dedicated calibration equipment, reducing installation effort and device complexity while still enabling drift detection.
Solution Approach 2:
The system performs self-calibration by comparing measurements from the first and second ionization electrodes. The recalibration process is automated and does not require external intervention or specialized calibration equipment, allowing the system to correct its own calibration drift using resources already present in the device.
3Measurement precision
If recalibration is performed frequently to maintain accuracy, then measurement precision is maintained, but time loss and operational interruption increase
Solution Approach 1:
The patent enables continuous or near-continuous operation during recalibration by maintaining productive combustion (lambda > 1.1) throughout the process. The system does not need to shut down or operate in non-productive modes during calibration, as the second ionization electrode allows measurements to be taken while the heater continues to function normally, minimizing time loss and operational interruption.
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 quick and low-expenditure recalibration of the control system, maintaining optimal lambda values and reducing the risk of carbon monoxide production and electrode damage, by using existing flame monitoring systems for recalibration purposes.
Implementation Method 1
an ionization measurement is performed in a flame region... An alternating voltage is applied to the ionization electrode. The flame region, which is ionized in the presence of flames, has a rectifying effect, so that an ionization signal flows primarily only during one half-wave of the alternating current.
Implementation Method 2
the recalibration is carried out by means of an ignition electrode present in the heater for igniting the combustion, which ignition electrode is operated to generate a second ionization signal
Data Source
Figure 1~2
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Figure 5
AI summary
The invention relates to a method for recalibrating calibration data of a first measuring system (S1) for measuring a first ionization signal in a flame area (2) of a heating appliance (1) operated with combustion air and fuel gas, wherein the first measuring system (S1) measures an ionization signal (I1) which is derived from a first ion current flowing from an ionization electrode (8) to a counter electrode (9) through the flame area (2), and from this determines and controls the ratio of combustion air to fuel gas (lambda) during combustion in the heating appliance (1) on the basis of calibration data, wherein the first measuring system (S1) is recalibrated at least according to predefinable criteria or at predefinable time intervals, and wherein the recalibration is carried out by means of an ignition electrode (7) present in the heating appliance (1) for igniting the combustion, which is operated to generate a second ionization signal (I2).The invention also relates to a device, in particular for carrying out the method according to one of the preceding claims, with a combustion chamber (1) having an air supply (3) and a fuel gas supply (4) which are controlled by a control unit (17), and with a first measuring system (S1) comprising an ionization electrode (8), a counter electrode (9), a first alternating current source (11) and a first evaluation electronics (13) for determining a first ionization signal (I1) which can be supplied to the control unit (17), wherein a second measuring system (S2) is provided for measuring a second ionization signal (I2) which can be generated by the second measuring system (S2) between an ignition electrode (7) provided for igniting a combustion and the counter electrode (9), and wherein the first (S1) and the second (S2) system are each configured to determine a lambda value.