中文摘要：

为了探究多缸机瞬时转速多谐次相位实用诊断方法，以内燃机扭振理论为基础，建立了瞬时转速的谐次诊断模型，从理论上分析了故障态下瞬时转速谐次幅值和相位的变化规律，并结合4120SG型柴油机单缸与多缸故障试验研究，提出了基于瞬时转速多谐次相位分析法的柴油机定位诊断技术，并提取了以谐次幅值和谐次相位为主的缸内做功故障诊断指标，确定了单缸与双缸故障态下瞬时转速的谐次诊断规则，并应用于实船12缸柴油机的故障诊断，取得了很好的效果。

英文摘要：

In order to explore the diagnosis of IAS multi-harmonic and phase technology, the instantaneous speed harmonic diagnosis model has been established based on the torsional vibration theory of the IC engine. The changes of the IAS （ instantaneous angular speed） harmonic amplitudes and phases were analyzed from the theory＇s point of view. When comparing the theory analysis with the research on the 4120SG diesel engine fault experiments, the fault diagnosis technology based on the instantaneous speed harmonic phase method was proposed and the diagnostic indexes were extracted in order to diagnosis the single-cylinder and multi-cylinder power faults. Finally, the harmonic ohase method was aoolied to diagnose the 12-cylinder marine diesel engine with zood results achieved.