The Detection And Study On Ion Current In A Gas Engine

ABSTRACT:In this paper, the mechanism of charged particles in reaction stage and high-temperature stage in cylinder is researched, and the causes of ion currents are studied form the theory. The significance of research is that ion current method could be used to monitor the engine running and optimize engine control, etc.In this paper, a current detection module which is placed at high voltage side of the ignition is developed, and ion current measurement is achieved based the module. The acquisition system software is developed based LabVIEW. Two kinds of cache are used to ensure high-speed data acquisition in the data acquisition unit, and data is processed by one-click in the data processing unit. Sources of interference signals are analyzed, and the origin signal is reduced noise by wavelet transform.The experimental studies of cyclic variation, ion current characteristics and affecting factors of ion current are carried out.The results of studies show that ion currents are sensitive to cyclic variation of the engine. It is advantage that cyclic variation could be studied based on ion current than the pressure in some respects. The polarity of spark plug has great impaction on the intensity of ion current. If center electrode polarity of spark plug is positive, ion current intensity is much greater. Ion current increases if the area of positive electrode increases, but there is little effect on the area of negative electrode. If the excess air coefficient is high, a lean fuel will affect the temperature and pressure in cylinder, and the ion current intensity will decrease. There is little effect on engine speed on ion current.