Wigner-Ville时频分布在内燃机故障诊断中的应用

Applications of Wigner-Ville Time-frequency Distribution in Internal Combustion Engine(ICE) Fault Diagnosis

针对内燃机瞬时转速信号的非平稳性特点 ,将时频分布理论用于转速信号的故障特征提取。使用动力学仿真方法得到了正常状态和微弱单缸减油状态下的瞬时转速 ,对比计算它们的Winger -Ville分布 ,发现时频分布图对功率不平衡性故障具有非常直观的可诊断性 ;这里Winger -Ville分布的交叉项起到了放大微弱故障信息的作用 ,极大地提高了对故障的敏感程度 ,在仿真中可侦测单缸减油仅 4%的模拟故障 ;使用实测的瞬时转速进行时频分布计算 ,经降噪处理后的时频分布图表现出了清晰的故障特征 ,证明是一种有效的基于瞬时转速故障特征提取的新方法。

A new method of extracting fault features based on transient speed signals was developed in which the time-frequency distribution theory was employed. The transient speed data was acquired while a decrease of injection oil mass for one cylinder at 6-135 type Diesel was evaluated by dynamic simulation. Then we calculated the Winger-Ville distributions of speed data, in which we faund the intercross item component of specific frequency that could indicate the existence of very weak fault. The intercross item is very sensitive to weak nonuniformities fault, could amplify the weak fault information greatly. At last the experimental transient speed signals were used to validate the method and the time-frequency distribution could show fault characteristics clearly also, then it was proved that the new method has good effects on fault diagnosis based on transient speed signals.