Ion Current Detection System With Isolated Terminals
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Solution Overview
Problem
Conventional ion current detection systems in internal combustion engines face challenges in accurately detecting ion current due to limited space around the cylinder head and the small amount of ions generated, leading to difficulties with simple detection circuits.
Innovation Solution
An ion current detection system utilizing an ignition assist device with heat-generating-element terminal portions positioned to avoid contact with the engine, allowing for accurate detection of ion current without electrical interference from the heat-generating-element circuit, using a glow plug with a ceramic member, heat-generating resistor, and ion detection electrode embedded in a ceramic composition, and a grounding cutoff switch to disconnect the heat-generating resistor from the cylinder head during detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an ion detection electrode is incorporated in a glow plug to save space, then the detection system can be installed in limited space around the cylinder head, but the small amount of ions generated during combustion results in small detectable current that cannot be accurately detected by simple detection circuits
Solution Approach 1:
The patent combines the ion detection electrode and heat-generating element into a single glow plug assembly, integrating two functions (ignition assistance and ion detection) into one component. This merging allows space utilization while enabling accurate ion current detection through the integrated structure's isolated terminal portions.
Solution Approach 2:
The patent introduces an intermediary structure (the glow plug body with isolated terminal portions) that separates the ion detection circuit from the heat-generating element circuit. This intermediary arrangement prevents electrical interference and allows accurate detection of small ion currents despite the presence of the heat-generating element.
2Reliability
If the heat-generating element is electrically connected to the cylinder head for grounding, then the glow plug can function properly for ignition, but the ion detection circuit becomes electrically affected and cannot accurately detect ion current
Solution Approach 1:
The patent segments the glow plug into distinct terminal portions: one for ion detection and another for heat-generating element connection. This segmentation electrically isolates the ion detection circuit from the heat-generating element circuit, allowing the glow plug to maintain its ignition function while enabling accurate ion current detection without electrical interference.
Solution Approach 2:
The patent divides the electrical connection paths into separate segments, with the ion detection electrode having its own independent terminal portion that does not come into contact with the cylinder head. This segmentation prevents the heat-generating element's electrical connection from interfering with ion current detection.
3Measurement precision
If terminal portions are positioned to avoid contact with the engine for isolation, then electrical interference is prevented, but connection to the terminal portions becomes more difficult
Solution Approach 1:
The proximal end portion of the glow plug serves multiple functions: it provides electrical isolation from the cylinder head for accurate ion current detection, and simultaneously serves as the location for all electrical connections (ion detection terminal and heat-generating element terminals). This multi-functional design maintains detection accuracy while facilitating connection ease.
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 accurate detection of ion current generated during combustion, improving combustion efficiency and exhaust gas component control by isolating the ion detection circuit from the heat-generating-element circuit, preventing leak currents and allowing clear identification of ion current waveforms.
Implementation Method 1
heat-generating resistor... adapted to supply electricity to the heat-generating element
Implementation Method 2
the amount of ions generated as a result of combustion in the internal combustion engine... detects the amount of generated ions in the form of the magnitude of ion current
Data Source
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AI summary
[Objective] To accurately detect ion current generated as a result of combustion in an internal combustion engine. [Means for Solution] An ignition assist device 10 includes a housing 12; a ceramic member 11 disposed in the housing 12 and having a distal end portion 11a exposed from the housing 12; and a heat-generating element 20 and an ion detection electrode 30 which are embedded in the ceramic member 11 in such a manner as to be electrically insulated from each other. The ignition assist device 10 further includes an ion detection terminal portion 31 for applying an ion detection voltage to the ion detection electrode 30, and two heat-generating-element terminal portions 21 and 22 disposed at such positions as to not come into contact with the internal combustion engine and adapted to supply electricity to the heat-generating element 20.