The Stability Of Roots Vacuum Pump Rotor System

Roots vacuum pump can be widely used because of its high pumping speed.At present,there is a larger vibration problem of roots vacuum pump.But 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 about the asymmetric roots rotor,gyroscopic effect and rotor-gear system 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)The dynamic model of roots rotor is constructed,and the dynamic equation is also established by Newton Euler method.The perturbation analysis is used to analyze the stability of the boundary equation.The stability boundary diagram of the system is obtained by boundary equations.Finally,the influence on the stability of different rotor parameters such as profile and length is studied in order to optimize the parameters of the rotor.(2)The influence on the stability of asymmetric roots rotor of gyroscopic is considered.The stability analysis of system equation is discussed by Floquet theory.The Newmark-P is used to verify correctness of equation.The influence of damping on stability is also verified by Newmark-?.(3)The asymmetric rotor is simplified as an asymmetric Euler beam model.The dynamic model and stability analysis of system is constructed.The stability boundary is acquired in the beam model and the gyroscopic is also considered.Finally,the unstable speed range of system is calculated with different gyroscopic moment.(4)The rotor-gear of the roots vacuum pump is constructed considering the influence on the stability of the time-varying stiffness.The dynamics equation is established by using Newton Euler model.The stability of the equation boundary equation of the system is acquired by using multiple scale method.The stability boundary of the system is obtained by using known parameters.The dynamic model and equation are established based on the asymmetric roots rotor,asymmetric Euler beam model,rotor-gear system.The stability boundary of system is acquired and the unstable speed range is calculated.The research results can provide theoretical reference for the working roots vacuum pump.