Ionic Current Convexity Detection for Preignition in Engines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing combustion state detection methods for internal combustion engines struggle to accurately detect preignition and its premonitory phenomenon, especially when smoldering occurs, as the characteristics of leak current and ionic current overlap, leading to erroneous detection and difficulty in grasping the appearance position of the ionic current based on combustion.
Innovation Solution
A combustion state detection apparatus with electrodes in the combustion chamber, voltage application means, ionic current detection means, data extraction means for setting detection intervals, convexity detection means to identify upwardly convex domains in ionic current changes, and preignition decision means that includes leak current judgment to distinguish between leak and ionic currents, allowing precise detection of preignition even with smoldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple ionic current detection is used to detect preignition, then detection simplicity is maintained, but detection precision deteriorates due to overlap with leak current during smoldering
Solution Approach 1:
The detection method is segmented into multiple processing stages: leak current detection in the primary current conduction period, ionic current detection in the combustion period, and differentiated analysis based on timing. This segmentation allows the system to handle leak current and ionic current separately, resolving the overlap problem while maintaining reliable preignition detection
Solution Approach 2:
The control unit acts as an intermediary that processes the raw ionic current signal through multiple analysis stages. It first detects leak current characteristics, then identifies true ionic current based on timing and convexity analysis, effectively mediating between the noisy signal and the final detection decision
2Measurement precision
If detection threshold is lowered to detect early ionic current, then detection sensitivity improves, but false detection increases due to leak current
Solution Approach 1:
The system performs preliminary detection of leak current during the primary current conduction period before combustion occurs. By identifying and characterizing leak current in advance, the system can set appropriate detection thresholds for the subsequent combustion period, improving sensitivity without increasing false detections
Solution Approach 2:
The system uses feedback from the detected ionic current characteristics (timing, magnitude, convexity) to adjust detection parameters. The control unit continuously monitors the ionic current and compares it against dynamically adjusted thresholds based on engine operating conditions and detected leak current patterns
3Speed
If conventional ionic current detection is used, then detection speed is maintained, but detection accuracy deteriorates when smoldering occurs
Solution Approach 1:
The detection process is segmented into distinct time periods: primary current conduction period for leak current detection, and combustion period for ionic current detection. This temporal segmentation enables simultaneous fast detection and high accuracy by processing different current types in their respective optimal windows
Solution Approach 2:
The detection system dynamically adjusts its analysis based on real-time signal characteristics. The control unit identifies the start of ionic current based on convexity changes and timing relative to ignition signal fall, adapting the detection criteria to each combustion event while maintaining consistent detection speed
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 reliable detection of preignition and its premonitory phenomenon, even in cases where a leak current is present due to smoldering, enhancing detection precision and preventing erroneous suppression control.
Implementation Method 1
detect an ionic current which appears in a case where a mixture combusts within the combustion chamber
Implementation Method 2
applying a voltage across the electrodes in order to detect an ionic current
Data Source
AI summary
A combustion state detection apparatus for an internal combustion engine, includes convexity detection means (30) for detecting that domain within the detection interval in which the change shape of the ionic current is upwardly convex, on the basis of the ionic current data extracted by data extraction means (20), and preignition decision means (40) including comparison setting means for setting a comparison value with which the upwardly convex domain is compared, and functioning to decide the occurrence of the preignition or the premonitory phenomenon thereof when the upwardly convex domain lies at a timing earlier than the comparison value, wherein the convexity detection means (30) includes leak current judgment means for judging the appearance of a leak current across electrodes, and it enables the detection of the upwardly convex domain when the appearance of the leak current has been judged.