基于轴系扭振的青藏线机车柴油机故障诊断方法及机理研究

The Qinghai-Tibet Railway has strategic significance on China’s economy and national defense. However, the unique geographical environment and climatic conditions will worsen working process, working state instability and system parameters nonlinearization of locomotive diesel engine, which will cause serious engine problems such as engine power drop, non-uniformity working of each cylinder and transmission parts damages, resulting in unsafe running of the railway line. Aimed at its operating and faults characteristics, this project intends to study the torsional vibration diagnosis method and mechanism of locomotive diesel engine in non-stationary condition on the Qinghai-Tibet Railway. Based on the research of shafting torsional vibration characteristics of diesel engine in non-stationary condition, by applying the vibration analysis method in arbitrary excitation, while considering nonlinear characteristics of system stiffness and damping parameters, the shafting dynamics nature of diesel engine power online monitoring, power uniformity diagnosis of each cylinder and shafting components fault diagnosis will be revealed, and a systematic fault diagnosis method based on torsional vibration for locomotive diesel engine working on the Qinghai-Tibet Railway will eventually be developed. The related research work meets the needs of national development strategy of mechanical equipment health monitoring in extreme environments, and its results will not only form a theoretical basis for the development of locomotive diesel engine condition monitoring and fault diagnosis system, which is urgently needed on the Qinghai-Tibet Railway today, but also become a general guidance to the fault diagnosis of internal combustion engine in non-stationary condition.

青藏铁路对我国经济、国防有着重要战略意义，但其特殊的地理环境和气候条件使机车柴油机工作过程恶化，运行工况不稳定性和系统参数非线性化加剧，极易造成柴油机功率下降、各缸做功不均匀、传动部件损坏等问题，直接影响铁路安全运行。针对青藏线机车柴油机的运行特性和故障特点，项目拟开展青藏线机车柴油机非稳定工况扭振诊断方法及机理研究。在研究柴油机非稳定工况轴系扭振特性的基础上，采用任意激励下的振动分析方法，并考虑系统刚度和阻尼等参数的非线性变化特性，揭示柴油机功率在线监测、各缸作功均匀性诊断和轴系部件故障诊断的轴系动力学机理，进而提出一套基于扭振信号的青藏线机车柴油机故障诊断方法。相关研究工作符合极端环境下机械装备健康监测这一国家发展战略需求，其成果不仅可为青藏线急需的机车柴油机状态监测与故障诊断系统开发奠定理论基础，而且对非稳定工况内燃机故障诊断具有普遍指导意义。

针对青藏线高原机车柴油机经常处于非稳定运行工况，极易造成柴油机功率下降、各缸作功不均匀和传动部件损坏等问题，项目开展了内燃机非稳态工况下轴系扭振动力学分析及故障诊断研究。研究了内燃机非稳态工况下的非周期性气缸激振力矩特性，推导了基于扭振单位脉冲响应的内燃机非稳态工况轴系扭振计算方法；研究了气体激振力矩和往复惯性力矩对曲轴测点处角位移幅值的影响，研究了轴系测点的某单谐次角振动位移幅值与内燃机输出功率的关系，提出了基于曲轴角振动单谐次幅值在线监测内燃机输出功率的方法；深入研究了过渡工况下基于轴系扭纵耦合振动的航空发动机扭振减振器故障失效机理；研究了轴系部件（弹联、扭振减振器）故障与柴油机轴系扭振模态参数之间的关系，并实现了基于代理模型的轴系部件故障诊断；同时进行了内燃机非稳态工况扭振分析、柴油机功率在线监测和轴系部件故障诊断的实验研究。研究结果可为青藏线急需的机车柴油机状态监测与故障诊断系统开发奠定理论基础，而且对内燃机非稳态工况的故障诊断具有普遍的指导意义。