Flame Ionization Current Detection Circuit with Dynamic Sensitivity Control
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Solution Overview
Problem
Existing flame detection circuits for ionization current measurement in combustion management systems are complex and expensive, making them inefficient for detecting a wide range of ionization currents, particularly in controlled combustion systems where lambda value 1 and CO peak determination are critical.
Innovation Solution
A device with a bypass circuit using a resistor and capacitor, employing a pulse-width-modulated signal to regulate the amplifier's input sensitivity independently of the ionization current, allowing for a high range of current detection with a simple and cost-effective design, and utilizing optocouplers for efficient signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex two-stage amplifiers or logarithmic amplifiers are used to detect a large range of ionization current, then measurement precision is improved, but device complexity increases and cost increases
Solution Approach 1:
The patent applies dynamics by making the amplifier's input sensitivity adjustable rather than fixed. A control device dynamically adapts the input sensitivity of the amplifier to match the actual ionization current level, allowing a single amplifier to effectively handle a wide range of current values without requiring complex multi-stage or logarithmic circuitry. This dynamic adaptation resolves the contradiction by providing high measurement precision across ranges while maintaining simple device architecture.
Solution Approach 2:
The patent changes the parameter of input sensitivity of the amplifier from a fixed value to an adjustable value controlled by a control device. By modifying this key parameter based on the ionization current level, the system achieves accurate detection across a large current range using a simple single-stage amplifier, thereby resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If high input sensitivity amplifiers are used to detect small ionization currents, then measurement precision is improved, but the amplifier saturates with large ionization currents
Solution Approach 1:
The control device dynamically adjusts the amplifier's input sensitivity based on the detected ionization current level. When ionization current is small, the amplifier operates at high sensitivity for precise detection. When ionization current becomes large, the control device reduces the input sensitivity to prevent saturation. This dynamic adjustment enables the amplifier to handle the full range of ionization currents effectively.
Solution Approach 2:
The system employs feedback through a control device that monitors the ionization current and adjusts the amplifier's input sensitivity accordingly. This feedback mechanism ensures the amplifier operates within its optimal range, preventing saturation while maintaining high precision for small currents, thus resolving the contradiction between measurement precision and adaptability.
3Device complexity
If simple circuits are used for ionization current detection, then device complexity is reduced and cost is reduced, but measurement precision deteriorates
Solution Approach 1:
The simple amplifier circuit serves itself by having its input sensitivity automatically adjusted by the control device based on the ionization current level. This self-adaptation enables a simple circuit to achieve measurement precision previously only attainable with complex circuits, resolving the contradiction between device simplicity and measurement accuracy.
Solution Approach 2:
By making the input sensitivity parameter adjustable, the simple amplifier circuit gains the capability to adapt to different ionization current levels, achieving high measurement precision without requiring complex circuit architecture. This parameter change transforms a simple circuit into a versatile, precise measurement device.
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 precise detection of ionization currents across a large range, providing real-time information for flame size inference and automatic burner control, effectively capturing subtle CO concentration peaks, thus meeting the requirements of controlled combustion systems with a simplified and cost-effective solution.
Implementation Method 1
an amplifier device (10) with an input (E) and an output (A), wherein an electrical voltage drop corresponding to an ionization current of the flame is generated at the input (E) of the amplifier device (10)
Implementation Method 2
A device with a bypass circuit using a resistor and capacitor, employing a pulse-width-modulated signal to regulate the amplifier's input sensitivity independently of the ionization current
Implementation Method 3
utilizing optocouplers for efficient signal processing
Data Source
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AI summary
Device (100) for determining an ionization current (I1) of a flame (40), comprising: - an amplifier device (10); and - a control device (20); - wherein the flame (40) is electrically connected to an input (E) of the amplifier device (10); - wherein, by means of the control device (20), an input sensitivity of the amplifier device (10) can be adjusted to a maximum value essentially independently of the ionization current (I1); - wherein a quantity of the ionization current (I1) can be determined from a control variable of the control device (20).