发动机振动信号不对称现象分析

某柴油机振动信号出现不对称现象,其最大值与最小值差异较大。该信号的频谱特性表明:在0-100 Hz频段内,存在发动机转速的2阶、4阶、6阶分量,其中2、4阶分量之间存在某种微妙的相位关系,导致其在时域叠加后出现不对称现象。本文进一步研究了2阶、4阶分量在800~3 000 r/min整个转速范围内的振动位移,发现低转速时比高转速时大87.5%以上。根据发动机力学模型认为这是由发动机倾覆力矩引起的,指明了改进方向,为该发动机的改进方案提供了检验依据。

Analysis of the Signal＇ s Asymmetry Based on the Engine Vibration

During a vibration measurement on diesel engine,found one of the signals was dissymmetrical, for its absolute values on maximum and minimum were different with each other distinctly. In the band of 0-100 Hz, there has been the 2nd, 4th and 6th orders of the engine rotation, and the frequency spectrum showed that the phase relationship between 2nd and 4th order was critical for the phenomenon. Then, this paper made a further research on the displacement of the 2nd and 4th orders in the engine scanning mode, from 800 to 3 000 r/min, found that the displacement in the low RPM speed was 87.5% larger than in high RPM speed. The model study indicated that it was caused by the engine overturning moment, and then this paper provided some improvement methods finally.