Mechanical Turbocharger Rotor Dynamic Characteristics Of The Study

Small size and high speed have become the main trends in the development of supercharger. To the scraping question of high rotational speed of supercharger, the dynamic behavior of the geared rotor system is researched, and this can offer theoretical basis for the design of supercharger. Geared rotor system is the most complex and key part in supercharger and its dynamic behavior directly determines the dynamic characteristics of supercharger. With the purpose of improving its stability of rotation and the dynamic behavior,some research is done based on supercharger matching with the 0.8L engine of Chery .In this paper, the whole system of model of the finite element theory are established by software ANSYS 11.0. The major works are as follows:The first, the contents and the methods of geared rotor dynamics are introduced in the paper, and the finite element method is also introduced briefly.The second, the model of finite element method of supercharger is established and by using Block Lanczos algorithm in order to get the first eight inherent frequency and inherent vibration figure of the system, and find that the first inherent frequency is in the normal rotational speed of supercharger, which is the main reason of vibration.Through the comparation of inherent frequency between coupling rotor system and the separate geared rotor,the action of coupling is revealed.The influence of bearing conditions, gear mesh stiffness and rotor length is studied to reduce the vibration and noise of supercharger .The third, on the basis of model computation, forced harmonic vibration analysis is finished by using ANSYS 11.0, then came to the system's frequency dynamic response curve.The displacement response curve of the key nodes on the surface of supercharger are computed. The maximum displacement of the system is 4.72×10^-3 mm at the rolling bearing 16003.The fourth, the influence of the gear meshing rigidity to the geared rotor system is analysed. With the variation of gear meshing rigidity, the low order inherent frequencys are microvariation, but the high order inherent frequencys are sharply.Increase the gear meshing rigidity could improve the system's inherent frequencys and reduce the vibration displacement.Besides, the meshing frequency of the geared rotor and the meshing frequency of gear pair is studied, and find that except the first order frequency and the second order frequency is not in the meshing frequency, other high order frequency is almost in it, this is another reason for the vibration of the geard rotor system. Without the pneumatic effect,the influence of gear excitation to the system is studied.The displacement of the axis of gear rotor is increased when the speed the supercharger up is revealed .Through simulation the maximun axial displacement that the gear excitation primary influenced is 7um,Last, an analysis about the experiments of supercharger's dynamics characteristics is also necessary. Through the amplitude—time response and the spectrum curve of the tested point on the surface of the supercharger ,the reason to the vibration and noisy of supercharger is found. The experimental result and the theoretically computed result are basically identical, so the established model is proved correctly.