Internal Combustion Engine Ion Current Detection Circuit
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Solution Overview
Problem
Conventional internal combustion engine combustion state detecting apparatuses face difficulties in accurately detecting combustion states across a wide operation region due to interference from spark discharging and high-speed combustion conditions, which hinder the detection of ion currents.
Innovation Solution
The apparatus includes an ignition plug with a circulation unit that short-circuits the primary winding during spark discharge, forming a circulation path and using a circulation current control unit to manage the circulation current, thereby controlling the changing electric current and ensuring accurate ion current detection across various operation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spark discharging is used for ignition, then combustion is initiated in the combustion chamber, but the electric current from spark discharging interferes with ion current detection
Solution Approach 1:
The patent segments the detection process into two distinct phases: spark discharging phase and ion current detection phase. By controlling the ignition apparatus to stop spark discharging before the ion current detection period begins, the system separates the interfering spark current from the detection period, enabling accurate ion current measurement while maintaining reliable ignition.
2Productivity
If combustion speed is increased for high-load operation, then power output is improved, but the ion current generation period becomes shorter and is embedded in the spark discharging period
Solution Approach 1:
The patent implements dynamic control of the ignition apparatus based on engine operating conditions. The control unit adjusts the spark discharging stop timing relative to the ion current detection period according to the detected engine state (such as rotation speed and load). This dynamic adjustment ensures that even under high-load conditions where combustion speed increases, the spark discharging is stopped early enough to allow clear ion current detection.
3Measurement precision
If spark discharging time is shortened to enable ion current detection, then ion current can be detected, but ignition energy may be insufficient
Solution Approach 1:
The patent employs periodic action by delivering full ignition energy in an initial spark discharging phase, then stopping the spark discharging to enter a detection phase where ion current is measured. This periodic pattern of ignition-discharge-detection ensures that sufficient ignition energy is provided during the active discharge phase while enabling accurate combustion state measurement during the subsequent detection phase.
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 configuration allows for stable and accurate detection of combustion states by minimizing interference from spark discharging and high-speed combustion, enabling effective ion current detection even under high-rotation-speed conditions.
Implementation Method 1
an ignition winding including a primary winding and a secondary winding magnetically coupled with the primary winding
Implementation Method 2
molecules of mixed gas in a combustion chamber of the internal combustion engine are ionized as the mixed gas in the combustion chamber combusts
Data Source
AI summary
An internal-combustion-engine combustion state detecting apparatus is configured in such a way as to include a circulation unit that short-circuits a primary winding so as to form a circulation path including the primary winding, while a spark discharge is produced in an ignition plug, and a circulation current control unit that controls a circulation current flowing in the circulation path and in such a way that based on an ion current detected by an ion current detection apparatus, the combustion state of an inflammable fuel-air mixture is detected.