提出了利用转速波动信号诊断内燃机失火故障的 3种方法 ,包括诊断模型方法 (1 )、波形分析方法(2 )和多特征综合方法 (3)。本文介绍了诊断模型方法。通过分析曲轴飞轮系统的动力学特性 ,建立了简明实用的瞬时转速诊断模型 ,揭示了瞬时转速波动信号与气体力扭矩及各缸气体压力之间的本质联系 ;进而将模型方程转换到频域内处理 ,定义了 4种诊断失火故障的无量纲特征参数 ,给出了这些参数的快速提取算法和故障识别方法。最后通过试验研究 ,验证了该方法的可行性和有效性 Three methods for diagnosing the misfiring of internal combustion engine based on rotational speed fluctuation signal are proposed, including diagnostic model method (1), waveform analysis method (2) and multi-feature synthesis method (3). This article describes the diagnostic model approach. By analyzing the dynamic characteristics of the crankshaft flywheel system, a concise and practical diagnostic model of instantaneous speed is established, and the essential relationship between the instantaneous speed fluctuation signal and the gas torque and gas pressure of each cylinder is revealed. Then, the model equations are transformed into the frequency domain processing , Defines four dimensionless characteristic parameters for diagnosing misfiring faults, and provides a fast algorithm for extracting these parameters and a method for fault identification. Finally, the experimental study shows that the method is feasible and effective