Ionizing Current Waveform Analysis for Humidity Detection
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Solution Overview
Problem
In internal combustion engines, the measurement of ionizing currents can mistakenly identify advanced ignition as humidity, leading to incorrect spark advance corrections, which cause overheating of exhaust valves and after-treatment devices, especially in turbocharged engines with significant air humidity.
Innovation Solution
A method to detect humidity in the combustion chamber by recognizing a stepped waveform in ionizing currents, inhibiting any corrective actions on spark advance and fuel injection when humidity is present, using an electric signal acquisition system that analyzes ionizing currents to differentiate between normal and humid conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ionizing current measurement is used to detect combustion conditions, then combustion analysis capability is improved, but measurement precision deteriorates due to false identification of humidity as advanced ignition
Solution Approach 1:
The patent applies waveform shape analysis to distinguish between different combustion conditions. The ionizing current waveform exhibits characteristic shapes: a first maximum for normal combustion, a second maximum for advanced ignition, and a stepped waveform for humidity presence. By analyzing the temporal pattern and shape characteristics of the ionizing current signal rather than relying solely on amplitude thresholds, the system can reliably differentiate humidity from advanced ignition conditions, resolving the measurement precision vs. reliability contradiction.
2Productivity
If spark advance correction is applied based on ionizing current analysis, then combustion efficiency is improved, but harmful factors increase due to overheating of exhaust valves and after-treatment devices
Solution Approach 1:
The patent implements a feedback control mechanism where the ionizing current waveform is continuously monitored and analyzed. When a stepped waveform indicating humidity is detected, the system provides feedback to inhibit spark advance correction, preventing the harmful effect of exhaust valve overheating. This closed-loop feedback ensures that combustion efficiency improvements are only applied when safe, resolving the contradiction between productivity and harmful factors.
3Ease of operation
If corrective actions are taken on spark advance, then combustion control is improved, but device complexity increases due to additional humidity detection requirements
Solution Approach 1:
The patent makes the existing ionizing current measurement system multi-functional by programming the control unit to perform both combustion analysis and humidity detection using the same sensor and processing hardware. The control unit analyzes waveform characteristics to determine both combustion efficiency and humidity presence, eliminating the need for separate detection devices. This universal approach improves combustion control while avoiding additional device complexity.
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
Prevents incorrect spark and fuel injection corrections, maintaining nominal engine operating parameters by accurately identifying humidity through ionizing current analysis, thus avoiding overheating issues in internal combustion engines.
Implementation Method 1
measurement of ionizing currents inside the combustion chamber of an internal combustion engine
Data Source
AI summary
A method for ignition control in a combustion chamber of an internal combustion engine by means of acquiring an electric signal relating to ionizing currents emitted in said combustion chamber, comprising a step of detecting a substantially stepped trend of said electric signal and a consequent step of inhibiting a corrective action of an ignition advance and/or of a fuel injection limitation curve in the combustion chamber.