在定容燃烧弹上,利用离子电流法,通过测量燃烧过程中的离子电流信号,对不正常点火进行了检测,即通过调整两对点火电极之间的间隙和点火时间,来模拟发动机火花塞和排气门附近的早火和后火等不正常点火情况.结果发现:不正常点火时,离子电流波形在形状及幅值上与正常点火时存在较大的差异,即火花塞电极附近发生早火时,离子电流波形在主点火信号之前出现了离子电流；排气门附近发生早火或后火时,离子电流波形出现了2个峰值,该离子电流第1峰值大于正常点火时的第1峰值,第2峰值小于正常点火时的第2峰值.该结果可为发动机不正常点火检测提供依据,且方法简单、易行.%With the ionic current method, the ionic current signal was detected during the combustion process on a constant volume combustion bomb for the detection of the abnormal ignition. Abnormal ignition such as pre-ignition and ignition after the main ignition was simulated by adjusting the distance and the ignition time between two electrodes. The results show that there were large differences between ionic current signals of abnormal ignition and normal ignition signals in the shape and amplitude when the abnormal ignition occurred. When the pre-ignition occurred near the spark plug, the ionic current already appeared before the main ignition signal; when the abnormal ignition occurred near the exhaust valves, the ionic current waveform had two peaks, and the first peak of the ionic current was larger than that at normal ignition and the second peak was lower than that at normal ignition. The results can provide the basis for the detection of abnormal ignition in engines, and the present method is simple and practicable.
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