Ignition-Coil Ion Current Detection for Single-Cylinder Misfires
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Solution Overview
Problem
Existing misfire detection systems in single cylinder IC engines face challenges due to low mechanical inertia and load disturbances, particularly in ignition coils with common electrical connections, leading to ineffective detection of misfires and increased emissions.
Innovation Solution
A misfire detection system utilizing an ion current measurement circuit with a biasing voltage circuit and signal processor, which measures ion current through a common connection of the primary and secondary windings of the ignition coil, effectively detecting complete and partial misfires by analyzing ion current patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional misfire detection methods (crankshaft acceleration monitoring) are used in single cylinder engines, then the detection system is simple, but the detection accuracy is poor due to low mechanical inertia and load disturbances
Solution Approach 1:
The patent replaces the mechanical crankshaft acceleration monitoring system with an electrical measurement system. Specifically, it uses an ion current measurement circuit connected to the spark plug to detect combustion events electrically, substituting the mechanical inertia-based detection method with an electrical field-based method that is not affected by low mechanical inertia or load disturbances.
Solution Approach 2:
The patent introduces an ion current measurement circuit as an intermediary between the combustion process and the detection system. The circuit measures ion current generated during combustion through the spark plug, providing an intermediate electrical signal that accurately reflects combustion quality without being influenced by mechanical factors.
2Reliability
If ion current measurement circuit is connected to secondary winding only, then the measurement circuit is simple, but it cannot effectively measure ion current in engines with common electrical connections
Solution Approach 1:
The patent segments the electrical connection path by introducing separate connection points on the primary and secondary windings. The ion current measurement circuit is connected to both windings through dedicated terminals, creating distinct measurement paths that prevent interference and enable reliable ion current detection even in engines with common electrical connections.
Solution Approach 2:
The patent adds an additional electrical connection dimension by connecting the measurement circuit to both primary and secondary windings simultaneously. This multi-dimensional electrical connection approach provides redundant measurement paths and enables the circuit to distinguish between ignition signals and ion current signals, improving measurement reliability.
3Object-affected harmful factors
If misfire detection is not implemented accurately, then the system operates simply, but emissions increase and catalyst performance degrades
Solution Approach 1:
The patent implements a feedback mechanism where the ion current measurement circuit continuously monitors combustion quality and provides real-time information about misfire events. This feedback enables the engine control system to detect and respond to misfires promptly, taking corrective actions to reduce emissions and protect the catalyst.
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
Accurate detection of misfires improves engine performance, reduces emissions, enhances vehicle reliability and durability, and provides driver comfort by preventing fuel wastage and catalyst degradation.
Implementation Method 1
measuring an ion current generated from the spark plug after a sparking event
Data Source
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AI summary
A misfire detection system (300) comprising an ignition system (303) including an ignition coil (107), an ion current measurement circuit (302) electrically connected to the ignition coil (107) for measuring an ion current generated from a spark plug (106), and a signal processor (401) for processing and conditioning the ion current measured by the ion current measurement circuit (302) to determine occurrence of a misfire in the IC engine, is disclosed. The ignition coil (107) comprises a primary winding (101) and a secondary winding (103), where a first end (101B) of the primary winding (101) is electrically connected to a first end (103B) of the secondary winding (103). Misfire detection improves reliability and durability of the IC Engine.