| The crttent trend is that high-pumping-speed vaccum pumps are greatly needed in those fields, such as space technology,new material and new energy. It means that high-pumping-speed two-stage sliding valve vaccum pumps need to be studied at stake. However, high-pumping-speed two-stage sliding valve vaccum pumps also,like one-stage sliding valve pumps, have the problem of large vibration and high noise.The vibration and noise are higher further speed. That has a crippling effect on the stability of the performance of the pump and cause serious pollution to the environment. Therefore,it is extremely important to study vibration and noise of the high-pumping-peed two-stage sliding valve vaccum pumps.In this paper,vibration and noise of that 2H-150 high-pumping-peed two-stage sliding valve vaccum pumps is studied, The main causes of vibration and noise of sliding valve pumps are analyzed. The model of motor system of rotary piston pump is established to calculate accurately the dynamic force of piston pumps, The research of dynamic incentive simulation of multibody dynamics of motor system of rotary piston pump, dynamic response analysis, noise radiation analysis of acoustic boundary element,sound intensity testing and noise source identification of exhaust chamber of rotary piston pump are described. The main research contents in this paper are as follows:(1) The noise and vibration generating mechanisms of high-pumping-peed two-stage sliding valve vaccum pumps is analyzed. The experiments show that the motion of the rotor system is the primary source of vibration, and the motion system of sliding valve pump is a non-linear system of vibration which produces wave-vibration.(2) Based on the theory of kinematics and dynamics of mechanical system, kinematics model of mechanical system of sliding valve pumpis established, the equations of the velocity and acceleration of the slide valve rod are analyzed to calculate its inertia force for the subsequent accurate calculation of two-stage rotary piston pump.(3) Based on the least square method, space force and torque of two-cylinder pump are analyzed to obtain the key parameters of balance weight at all levels, the author puts forward the concept of multistage balance. The two-stage dynamic balance of rotary piston vacuum pump is accurately calculated.(4) Based on computational dynamics of multibody systems to establish multi-rigid-body dynamics model of the two-stage sliding valve pump, the simulation and vibration response are analyzed. Through the simulation the forces of the two-stage rotary piston pump system are analyzed to get the displacement and amplitude of vibration, which means the accurate and reliable response of vibration have been gotten.(5) Based on the acoustic theory and resistant muffler, the acoustic model of exhaust cavity structure is established. The expression of the transferring power coefficient and transmission loss of the acoustic mode 1 of are deduced, for providing the theory basis for the noise reduction of two-stage rotary piston pump.(6) The method of large eddy simulation and acoustic analogy is used to predict and calculate noise of evacuation system of two-stage rotary piston vacuum pump. The model of flow field and acoustic field on variable cross-section exhaust pipe cavity is established to get the sound pressure and determine the radiation directivity of aerodynamic noise, which providing the reference data for engineering experiment.(7) As the reference body, the evacuation of the two-stage rotary piston pump is tested through testing the sound pressure, which help to ananlysis its sound pressure and sound intensity and the radiation directivity of aerodynamic noise. By means of processing the acoustic pressure data, the noise power spectrum and the radiation directivity distribution are analyzed to analyze and identify the main noise frequency components of evacuation system of two-stage rotary piston pump. |
PDF Full Text Request