外部激励下增压器轴系振动规律研究

Vibration Law of Turbocharger Shafting under External Excitation

车辆行驶过程中路谱激励通过车轮和车身传递到发动机,加之发动机本身运作时产生的振动激励,最终传递到涡轮增压器上,统称为外部激励。外部激励作用在涡轮增压器壳体和轴承体上,经由两个浮环轴承传递到轴上,影响增压器轴系运动的稳定性。通过采用有限元的分析方法,建立了涡轮增压器总成多体动力学模型,在此基础上模拟增压器总成受到来自发动机的外部激励时轴系的振动响应。在激振试验台上模拟增压器总成受到外部激励时的响应情况,分别施加原始振动信号和该信号缩小至原来的0.5倍、0.25倍和0.125倍后的振动信号,轴系的振动响应也呈现出对应的线性规律,采用4种振动信号求得的传递函数也基本一致。通过激振台试验验证有限元模型仿真结果的准确性,发现在0~800 Hz频率段轴系振动的试验值与仿真值基本吻合,验证了有限元方法用于计算轴系振动响应的可行性,为解决增压器轴系振动问题提供了新的解决办法。

The excitation of uneven road will transfer to the engine through the vehicle wheel and body during the driving,which mixes with the generated vibration excitation of engine operation and ultimately transfers to the turbocharger.These excitations are collectively referred to as external excitation.External excitation acts on the turbocharger housing and bearing body and then transfers to the shaft through two floating-ring bearings,which affects the stability of the turbocharger shaft system.In order to solve the problem,the finite element analysis method was used to establish a multi-body dynamic model of turbocharger assembly.The vibration response of shaft system was then simulated on the vibration test bench when the turbocharger assembly was subjected to external excitation from the engine.The 0.5 times,0.25 times,and 0.125 times of original signal and itself were applied respectively.The vibration response of shaft system showed a corresponding linear pattern.The transfer functions obtained by four vibration signals were basically consistent.The simulation accuracy of finite element model was verified through the vibration test bench experiment.The experimental results were consistent with the simulation results in 0-800 Hz frequency range,which verified the feasibility of using the finite element method to calculate the vibration response of shaft system.Accordingly,a new solution was provided to solve the vibration problem of turbocharger shaft system.