中文摘要：

为解决瞬时转速方法在诊断多缸中高速V型机发生失火故障时,存在的特征参数难以提取、诊断精度不高等问题,以发火间隔角不均匀的某V12柴油机为对象,进行了基于集总经验模态分解（EEMD）和极坐标表示的诊断方法研究。结果表明：构成本征模态函数IMF6分量的主频率为8.3Hz（0.5谐次）,经过EEMD分解提取了0.5谐次成分,其幅值可作为判别单缸失火故障的特征值;将0.5谐次相位及其变化规律与极坐标表示结合,能够直观准确地定位故障。

英文摘要：

In order to extract the time domain characteristic parameters and guarantee the diagnosis accuracy in high speed V-engine with high number of cylinders,the fault diagnosis method of IAS was studied by taking V12 diesel engine with unequal firing angel as object based on EEMD and polar representation.Results show that intrinsic mode function 6（IMF6）has a main frequency component of 8.3Hz（0.5harmonic order）.The 0.5harmonic order components are extracted effectively by EEMD and its amplitude may be used as an characteristic value of misfire faults.The misfire cylinder may be located accurately through the combination of polar representation,0.5harmonic order phases and its change rules.