Dual Ignition Plug Ion Current Detection for Pre-Ignition
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Solution Overview
Problem
Existing internal-combustion-engine combustion condition detection systems struggle to accurately detect pre-ignition and precursor phenomena in multipoint ignition systems, leading to poor driving conditions and potential ignition plug or piston melting due to incomplete combustion ion current detection during ignition discharge.
Innovation Solution
The system employs a dual ignition plug configuration with a second ignition plug spaced apart from the primary plug to detect combustion ion currents independently of the ignition discharge, allowing for accurate pre-ignition detection through ion current analysis and ignition timing adjustments to prevent premature combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single ignition plug is used to ignite the fuel-air mixture, then the ignition system is simple, but pre-ignition detection accuracy is insufficient
Solution Approach 1:
The patent divides the ignition system into multiple independent ignition plugs (first ignition plug and second ignition plug) positioned at different locations within the combustion chamber. Each ignition plug has its own ion current detection capability, allowing independent monitoring of combustion conditions at different zones. This segmentation enables more accurate pre-ignition detection by providing multiple measurement points throughout the combustion chamber.
2Measurement precision
If ion current detection is performed during ignition discharge, then combustion ion current can be detected, but detection accuracy is reduced due to interference from ignition discharge
Solution Approach 1:
The patent performs ion current detection at the second ignition plug before the main combustion process begins. By detecting ion current at this early stage (during the discharge of the second ignition plug but before the first ignition plug completes its discharge), the system can identify pre-ignition conditions and combustion speed without being interfered with by the main ignition discharge of the first ignition plug. This preliminary detection action allows accurate measurement despite the presence of ignition discharge interference.
3Power
If high compression ratio is employed to improve engine efficiency, then power output increases, but pre-ignition occurs more frequently
Solution Approach 1:
The patent implements a feedback mechanism where the ECU continuously monitors ion current from the second ignition plug and compares it against reference values. When ion current indicates pre-ignition conditions (such as when combustion speed exceeds a threshold), the ECU receives feedback signals and automatically adjusts ignition timing or other combustion parameters to prevent actual pre-ignition events. This closed-loop feedback system allows the engine to operate at high compression ratios while preventing harmful pre-ignition through real-time detection and corrective action.
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 enhances the accuracy of combustion condition monitoring and pre-ignition detection, maintaining optimal combustion conditions and preventing engine damage by allowing for timely intervention in pre-ignition events.
Implementation Method 1
when a transistor 36 is controlled by an ECU (Electronic Control Unit) 42 to be turned off, counter electromotive force is produced across a primary coil 31; in response to the occurrence of the counter electromotive force, a negative high voltage is produced across a secondary coil 32, whereby the ignition plug 1 discharges
Implementation Method 2
when a fuel-air mixture in a combustion chamber 33 combusts, an ion-current detection device 41 detects an ion current that is caused by the combustion and flows across the electrodes of the ignition plug 1
Data Source
AI summary
An internal-combustion-engine combustion condition detection apparatus that can accurately comprehend a combustion condition is obtained. The internal-combustion-engine combustion condition detection apparatus includes an ion-current detection device (41) that detects an ion current generated during combustion and ignition devices including a first ignition device (21) having a first ignition plug (11) that causes main combustion in a combustion chamber (33) and a second ignition device (22) having a second ignition plug (12) disposed in the same combustion chamber (33) as and spaced apart from the first ignition plug (11) of the first ignition device (21); the ion-current detection device (41) detects a combustion ion current that is generated in the second ignition device (22) regardless of whether or not ignition is performed by the second ignition device (22), thereby detecting pre-ignition or a precursor phenomenon of pre-ignition.