Ion Sensor Voltage Control for Combustion Monitoring
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Solution Overview
Problem
Ionization signals in internal combustion engines weaken with increased exhaust gas recirculation or lean air/fuel mixtures, making it difficult to obtain a useful signal under varying engine conditions.
Innovation Solution
A method and controller implementation that supply a low voltage at the beginning of a combustion cycle to prevent premature ignition, followed by a high voltage based on crankshaft angle to increase the ion sensor current above a threshold, with the high voltage exceeding 400 volts and being discontinued at a specific crankshaft angle to enhance ionization sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage is supplied to the ion sensor continuously, then the ion sensor current is maintained above threshold, but premature ignition of fuel occurs in the combustion chamber
Solution Approach 1:
The patent applies periodic action by supplying high voltage to the ion sensor only during specific crankshaft angle windows rather than continuously. The controller activates high voltage during defined intervals (e.g., 10-25 degrees after top dead center) and deactivates it outside these windows, creating a periodic on/off pattern that prevents premature ignition while maintaining measurement precision during active periods.
Solution Approach 2:
The patent implements preliminary action by supplying low voltage to the ion sensor before the high voltage window begins. This preliminary low voltage supply prepares the sensor and prevents any potential premature ignition that might occur during the transition to high voltage, ensuring safe operation before the measurement window opens.
2Productivity
If exhaust gas recirculation or lean air/fuel mixtures are increased, then engine efficiency is improved, but the ionization signal weakens making it difficult to obtain useful signal
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage supplied to the ion sensor based on detected ionization signal strength. When the signal weakens due to high EGR or lean mixtures, the controller increases the voltage magnitude during the ionization window to compensate and maintain the current above threshold, effectively counteracting the weakening effect of the altered combustion parameters.
Solution Approach 2:
The patent implements dynamics by making the voltage supply to the ion sensor adaptive rather than fixed. The controller continuously monitors the ionization signal and adjusts the voltage parameters (magnitude and timing) in real-time based on combustion conditions, allowing the system to maintain measurement precision across varying engine operating conditions including high EGR and lean mixtures.
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 approach effectively increases the ion sensor current above a threshold, improving combustion characteristics monitoring and overcoming signal weakness issues due to exhaust gas recirculation or lean air/fuel mixtures.
Implementation Method 1
Ionized particles may conduct electricity across an electrical gap formed between two contacts, thereby closing an electrical circuit and allowing current to flow through the gap
Implementation Method 2
supplying, to an ion sensor fluidly coupled to a combustion chamber of the engine a low voltage at a beginning of a combustion cycle to generate an ion sensor current and a high voltage during an ionization voltage window
Data Source
AI summary
An internal combustion engine, a method of operating the internal combustion engine, and a controller are disclosed. The method may be implemented in part by the controller and comprises determining a shaft angle of an engine shaft; supplying, to an ion sensor fluidly coupled to a combustion chamber of the engine a low voltage at a beginning of a combustion cycle to generate an ion sensor current and a high voltage during an ionization voltage window based at least in part on the shaft angle, wherein the low voltage is configured to prevent premature ignition of fuel in the combustion chamber and the high voltage exceeds the low voltage and is configured to increase the ion sensor current above a current threshold.