内燃机的瞬时转速包含着各个缸燃烧状态的重要信息,可以用于分析各个缸做功状态,诊断缸体点火相关故障,如燃料泄漏、气门泄漏和点火异常等故障.通过模型建立从理论上分析瞬时转速与气体压力扭矩、往复惯性力扭矩和阻力矩之间的关系,提出4个特征参数表征瞬时转速波动率波形及谐波特征,并通过仿真数据和实测故障数据证明瞬时转速波动率对于分析诊断内燃机点火故障的有效性,实现内燃机点火状态的早期预警.%Instantaneous angular speed fluctuation ratio (IASFR) of a diesel engine contains a lot of information about gas pressure in cylinders, which can be used to diagnose combustion-related faults and other kinds of faults affecting the gas pressure, such as fuel leakage in fuel system, valve leakage, ignition fault, etc. A dynamic model was presented, and the relationships between the instantaneous angular speed and the gas pressure torque, inertia torque and load torque were analyzed theoretically. Four time domain parameters were proposed to describe the features of IASFR waveform and the characteristics of its harmonics. The effectiveness of the method presented was verified by a set of simulation data and a fault instance regarding the diesel engine ignition problem. An early warning method for diesel engine ignition condition was further provided.
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