基于曲轴扭振信息识别的柴油机失火气缸判别方法

为解决柴油发动机在高转速、低负荷工况下难以准确判断出发生失火故障的气缸的问题,提出了通过检测曲轴转速信号中的扭振信号起始点来判定失火气缸的故障诊断方法。该方法首先通过分析单缸失火时的转速信号以确定曲轴扭振的自由频率,然后基于该频率构造正弦检测信号,将该检测信号与各缸做功转角范围内的转速信号做内积运算,并得到的内积值作为失火气缸的指示特征。在6缸柴油机上的失火试验证明该方法能够在高转速低负荷情况下准确识别发动机的单缸失火和两缸失火,弥补了传统失火诊断方法工况覆盖率低的不足。

Judgment of Diesel Engine Misfire Cylinders Based on Crankshaft Torsional Vibration Detection

To handle the difficulty of judging fault cylinders in diesel engine misfire failures under high speed and low load conditions, a method that discerns fault cylinders by detecting the start points of crankshaft torsional vibration in rotation speed signal was proposed. With analyzing the rotation speed signal pattern in single-cylinder failure, this method first determined the natural frequency of crankshaft torsional vibration, through which a sine vibration detection signal was built. Then, the inner product of the detection signal and speed signal during the working strokes of cylinders were calculated, which were used as indicators of fault cylinders. As the misfire experiment on a six-cylinder diesel engine indicated, the proposed method can diagnose single-cylinder and double-cylinder misfire faults with high accuracy under high speed and low load conditions, which makes up for the deficiency of conventional diagnosis methods as low working condition coverage ratio.