Corona Discharge Ignition Combustion Start Detection
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Solution Overview
Problem
Existing methods for identifying the start of combustion in internal combustion engines using corona discharge ignition devices lack accuracy in determining the precise timing of combustion onset due to noise and interfering signals, affecting motor control and efficiency.
Innovation Solution
A method that evaluates extrema in electrical variables such as resonance frequency, impedance, or phase between current and voltage to identify the start of combustion, utilizing predefined intervals and derivatives to distinguish genuine combustion extrema from noise, and calculates a sliding average for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical variables of the resonant circuit are used to identify combustion start, then information about combustion chamber conditions can be obtained, but noise and interfering signals reduce measurement accuracy
Solution Approach 1:
The evaluation of electrical variables is segmented into specific crankshaft angle intervals. The method divides the combustion cycle into predefined intervals (e.g., before TDC, around TDC, after TDC) and evaluates extrema only within relevant intervals, thereby isolating genuine combustion signals from noise occurring at other times.
Solution Approach 2:
Different evaluation criteria are applied to different crankshaft angle intervals. The method assigns different weights and evaluation thresholds to extrema occurring at different positions in the combustion cycle, allowing more reliable intervals to have greater influence on the final combustion start determination.
Solution Approach 3:
The method performs preliminary evaluation of multiple electrical variables (resonance frequency, impedance, phase) across multiple crankshaft angle intervals before making the final combustion start determination. This preliminary analysis of derivatives and extrema positions allows filtering of false signals before final interpretation.
2Reliability
If multiple electrical variables are evaluated to improve detection reliability, then measurement accuracy increases, but device complexity increases
Solution Approach 1:
The resonant circuit serves multiple functions: it provides the corona discharge ignition function while simultaneously acting as a sensor for combustion detection. The same electrical variables (resonance frequency, impedance, phase) used for ignition control are also evaluated for combustion start identification, eliminating the need for separate sensing hardware.
Solution Approach 2:
The corona discharge device itself generates the measurement signals through its interaction with the combustion chamber environment. The electrical variables of the resonant circuit automatically reflect combustion chamber conditions (temperature, pressure, composition) without requiring external sensors, allowing the system to monitor its own operational state.
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
Accurately determines the start of combustion, reducing fluctuations and measurement errors, and provides reliable information for engine control by identifying global extrema and their derivatives, enhancing combustion timing precision and engine performance.
Implementation Method 1
a fuel/air mixture is ignited by a corona discharge
Implementation Method 2
an electrical resonant circuit, in which an ignition electrode that is electrically insulated with respect to combustion chamber walls constitutes a capacitor together with the combustion chamber walls
Data Source
AI summary
The invention relates to a method for detecting the start of combustion in a cyclically operating internal combustion engine in which a fuel/air mixture is ignited by means of a corona discharge, wherein, to generate the corona discharge, an electrical resonant circuit is excited, in which an ignition electrode that is electrically insulated with respect to combustion chamber walls constitutes a capacitor together with the combustion chamber walls, and, to identify the start of combustion, an electrical variable of the resonant circuit is evaluated. The position of an extremum is evaluated, the extremum occurring in the course of the electrical variable after ignition of the corona discharge and before extinguishment thereof, or the course of the electrical variable is compared with a reference course, wherein a threshold value is predefined and fuel combustion is concluded on the basis of a deviation by more than the threshold value.