Ion Current Signal Segmentation for Combustion Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for monitoring combustion processes in internal combustion engines face challenges such as cylinder air/fuel ratio imbalances, sensitivity to auxiliary parameters, stochastic ion current fluctuations, and noise in ion current measurements, which affect the accuracy of air/fuel ratio estimation and engine control.
Innovation Solution
A method that divides the ion current signal into crank angle subintervals, calculates the area of ion current in these subintervals, and computes dimensionless features using relative measures to reduce amplification impact, enabling robust combustion parameter estimation and adaptation to varying engine conditions, while integrating electronic circuits close to the ion current measurement source to mitigate noise and temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If ion current measurements are used to detect combustion parameters, then combustion monitoring capability is improved, but sensitivity to auxiliary parameters (air humidity, fuel quality, temperature) causes measurement precision to deteriorate
Solution Approach 1:
The ion current signal is divided into multiple crank angle subintervals, with different intervals capturing different combustion phase information. By segmenting the signal and analyzing specific intervals (e.g., chemi phase vs. thermo phase), the method isolates combustion-related features from auxiliary parameter effects, improving measurement precision while maintaining detection capability.
Solution Approach 2:
The patent transforms the ion current signal by computing derivatives with respect to crank angle and applying dimensional analysis to create dimensionless parameters. These transformed parameters exhibit reduced sensitivity to auxiliary parameters like temperature and humidity, while preserving combustion state information, thereby resolving the precision issue.
2Device complexity
If global lambda sensor is used to measure average air/fuel ratio, then device complexity is reduced, but cylinder imbalance detection capability deteriorates
Solution Approach 1:
The spark plug ion current serves as an intermediary measurement that provides cylinder-specific combustion information without requiring individual lambda sensors for each cylinder. The ion current signal acts as a mediator that translates combustion chamber conditions into measurable electrical signals, enabling precise cylinder-level monitoring while maintaining system simplicity.
3Reliability
If ion current signal amplitude is increased for better signal-to-noise ratio, then detection reliability is improved, but sensitivity to amplification variations causes measurement precision to deteriorate
Solution Approach 1:
The patent applies dimensional analysis to transform the ion current signal into dimensionless parameters by dividing by characteristic values (e.g., maximum ion current, crank angle intervals). This parameter transformation eliminates dependence on absolute signal amplitude and amplification variations, maintaining precision while allowing reliable noise-filtered measurements.
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 provides stable and reliable combustion parameter estimation, enabling effective balancing of cylinder processes, detection of fuel quality changes, and adaptation to different engine operating conditions, improving engine performance and reducing emissions.
Implementation Method 1
The current will be inversely proportional to the resistance of the gas in the cylinder, which in turn depends on cylinder pressure, temperature, fuel additives, and air humidity as well as other factors.
Implementation Method 2
The ion current is extracted by applying a voltage over the electrodes of the spark plug and then measure the current resulting from the voltage.
Implementation Method 3
combustion processes in a combustion engine
Data Source
AI summary
A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; 5 ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are 10 retrieved and used in combination.