Structure Design And Optimization Of Variable Pitch Screw Vacuum Pump

In this paper,the 180L/s variable pitch screw vacuum pump is taken as the research object,and its structure design and optimization are studied.From the view of thermodynamics were studied on the structure of the gap value of the thermal deformation,from the point of view of dynamics and analyzes the influence of different rotor structure of screw vacuum pump dynamic balance performance,and provide a theoretical basis for the design of a series of variable pitch screw vacuum pump,and provide a theoretical basis for the design of screw pump rotor parameters.The main contents are as follows:(1)Using the related theory of thermodynamics,fluid mechanics,analysis of the thermodynamic process of variable pitch screw vacuum pump rotor,established the finite element of four kinds of different structure of rotor model with third kinds of thermal boundary conditions,the simulation analysis of temperature field and thermal deformation.The distribution of temperature field and the distribution of thermal deformation of the equal pitch and variable pitch rotor are compared,and the distribution of thermal deformation of four kinds of structures is described.(2)Considering the thermal deformation of the rotor and the pump cavity distribution,influence of thermal deformation of the rotor and the pump cavity five gap value,the gap structure optimized.The thermal deformation analysis of rotor with different pumping speed and variable pitch screw pump is carried out.The variation rule of rotor size and thermal deformation is studied,and the formula for calculating the gap structure value is concluded.(3)Based on the theory of dynamics,a dynamic analysis model of active rotor and driven rotor is established.The critical speed of the model is obtained through first order modal analysis,and the dynamic balancing design of rigid rotor can be determined by dynamic equilibrium theory.By calculating the rotor's unbalance and adopting the method of increasing the mass at the end of the model,the effective dynamic balance is achieved.The 1-4 order modal analysis of the rotor before and after the dynamic balance design is given,and the influence of different rotor structure on the dynamic balancing performance of the screw vacuum pump is studied.(4)According to the research results,the structure of the rotor,the pump cavity,the gap structure,the shaft system,the cooling structure,the intake and exhaust port and other important components are optimized,and the structure design of the 180L/s variable pitch screw vacuum pump is completed.