车用柴油机湿式气缸套振动特性分析

Vibration Characteristics of Wet Cylinder Liner of Vehicle Diesel Engine

目的通过对柴油机湿式气缸套振动特性的计算分析,研究气缸套失效的主要原因,以提高柴油机结构的可靠性。方法基于16V280ZJ型柴油机气缸套的结构参数,采用有限元法建立气缸套有限元分析模型,对其进行模态分析,包括自由模态以及约束模态,分析气缸套的固有振动特性。然后基于16V280ZJ型柴油机的性能参数,计算气体力与惯性力,从而计算得到气缸套承受的交变侧压力。通过时-频转化将交变侧压力谱转化为频域谱,以分析气缸套承受的激励特性。结果气缸套的模态振型主要为径向弯曲振动,说明径向刚度小于轴向刚度。气缸套承受的交变侧压力的频率低于气缸套的固有频率。结论柴油机湿式气缸套受活塞侧向激振力不会发生共振,缸套的径向刚度较小,导致激振力传递给冷却水后缸套会发生穴蚀。

Objective To study the main reasons for the cylinder liner failure through calculation and analysis of the vibration characteristics of the diesel engine wet cylinder liner,to improve the reliability of the diesel engine structure.Methods Based on the structural parameters of the cylinder liner of 16 V280 ZJ diesel engine,the finite element analysis model of cylinder liner was established by finite element method,and the modal analysis was carried out,including the free mode and the constrained mode.The inherent vibration characteristics of the cylinder liner were analyzed.Then,based on the performance parameters of the 16 V280 ZJ diesel engine,the gas force and the inertial force were calculated,and the alternating side pressure of the cylinder liner was calculated.The alternating side pressure spectrum was converted into a frequency domain spectrum by time-frequency conversion to analyze the excitation characteristics of the cylinder liner.Results The mode shape of the cylinder liner was mainly radial bending vibration,indicating that the radial stiffness was less than the axial stiffness.The frequency of the alternating side pressure experienced by the cylinder liner was lower than the natural frequency of the cylinder liner.Conclusion The wet cylinder liner of the diesel engine is not resonated by the lateral excitation force of the piston,and the radial rigidity of the cylinder liner is small,which causes cavitation of the cylinder liner after the excitation force is transmitted to the cooling water.