对某V型12缸柴油机缸盖振动燃烧段信号进行分析,研究了针阀落座、缸内爆发响应信号的时域特点及频域特点.利用数字积分法由加速度信号获得速度信号,通过峰值速度表征最大压力升高率,峰值速度位置表征最大压力升高率出现时刻,峰值前拐点位置表征燃烧始点.利用动态双阈值进行针阀落座信号时间检验,落座信号开始点表征落座时刻,峰值加速度表征针阀落座强度.在转速n≤1400 r/min,负荷240～1350 N·m工况下利用振动信号提取的特征可以正确反映柴油机喷油及燃烧信息,能够对柴油机喷油及燃烧异常状态进行分析诊断.%The combustion stage signals of cylinder head vibration for a V-typed 12-cylinder diesel engine were analyzed. The time domain and frequency domain characteristics of injector needle valve seating and in-cylinder combustion response signal were studied. With the digital integration, the acceleration signal was transformed into the velocity signal. In the velocity signal, the peak, the peak position and the knee point before peak indicated the maximum pressure rise rate, the moment of maximum pressure rise rate and the combustion timing respectively. Inspecting the needle valve seating signal with the dynamic dual-threshold value method, it was found that the beginning point of seating signal indicated the seating moment and that the peak acceleration indicated the seating strength. In the conditions of no more than 1 400 r/min and 240-1 350 N · m, the extracted characteristics of vibration signal reflected injection and combustion information accurately and can be used to diagnose abnormal injection and combustion.
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