Vibration Analysis For A Certain Type Roots Vacuum Pump

Roots vacuum pump can be widely used because of its high pumping speed.At present,the roots vacuum pump that is running smoothly and low noises is needed urgently with the increasing environmental requirements.Therefore,the roots vacuum pump vibration analysis is a very important research topic.This paper is mainly analysis the effect of asymmetric roots rotor,material resistance,gear stiffness fluctuation and clearance to the vibration of roots vacuum pump.The dynamic model and stability analysis of system is constructed.The stability boundary is determined.The main contents of this paper include the following aspects:(1)Continuous asymmetric rotor dynamics model is established,using the Lagrange principle to establish the dynamic equation of the model.Using multi-scale method solve the equation.Then analysis the asymmetric rotor’s influence on vibration.It was found as a result of the existence of asymmetric rotor,the rotor in some cases can appear vibration instability.it is concluded that the stability boundary equations of the system.The stability boundary curve is drawn according to the stability boundary equation of the system.In order to consider the influence of the rotor resistance,establish the dynamics equations model considering the rotor resistance based on the original equation of continuous rotor dynamics model,and the method of multiple scales is used for the solution,it is concluded that the stability of the system boundary equation.The influence of asymmetry stiffness and internal resistance on rotor vibration stability is analyzed.(2)Considering the gear mesh stiffness fluctuation,the gear tooth surface meshing damping and the friction influence the transmission system,established gear system dynamics model.then through multi-scale analysis method,got the stability boundary curve of the system when considering wave stiffness of gear.The influence of different gear meshing damping and tooth surface friction coefficient on vibration stability of gear system is analyzed.(3)The model of the roz vacuum pump is simplified as a rotor-gear-bearing system model,and the motion differential equation including gear meshing and stiffness fluctuation of rolling bearing is established.Longge kuta method is used to solve dynamic equations.Then plot bifurcation diagram changing some factor.Plot the response of the graph,the poincare section,phase plan and the spectrum diagram,and analysis the tooth clearance and bearing clearance influence on the system vibration.Based on the asymmetric roots rotor,taking into account the damping force in a shaft,gear meshing fluctuation and clearance,eatablished the nonlinear motion differential equations.Then analysis different nonlinear factors influence on the vibration of the roots vacuum pump.The results of this study can provide theoretical reference for the design of rotz vacuum pump.