The Study And Optimization Of Dynamic Seal Of Screw Vacuum Pump Based On Tribology

The seal structure of screw vacuum pump was taken as the research object. This paper mainly focused on sealing pump at the end near the pump's vent. The dynamic characteristics of dynamic seal and its influencing factors were studied. A type of mechanical seal with micro-pores face was proposed to be used in screw vacuum pump. Based on tribology principle, the mechanical seal on the outlet side has been optimized by using surface texture technology to improve the lubrication and friction properties of the mechanical seal surface.By combining the relevant theoretical knowledge of hydrodynamics and surface texture technology, theoretical analysis model of mechanical seals with micro-pores face was established. The dynamic characteristics and the film thickness of the lubricating fluid of dynamic seal were studied. The impact of texture parameters, including the depth and density of the hole, on the friction characteristics and sealing performance of the mechanical seal was analyzed. The calculation methods of leakage, friction power, end face temperature and other performance parameters of the textured dynamic seal were proposed and the optimized design scheme of dynamic seal at the end near the pump's vent was given.The sealing performance of mechanical seal with different geometric shapes of micro-pores face was studied. The results showed that the sealing effect of cylindrical porous mechanical seal is the best. In comparison to mechanical seal with smooth face, the friction power consumption and temperature rise are greatly reduced. The improved seal can meet the seal require of screw vacuum pump and has application value.The influence of the rotor's temperature at the exhaust end on sealing performance was studied. A new screw vacuum pump with seal water cooling structure was designed and the three-dimensional finite element model of screw rotor with local cooling system was established. Temperature of seal shaft section was obtained by analyzing the temperature distribution of rotors. The results showed that the operating temperature of the seal assembly at the discharge end was significantly reduced. It can meet the temperature requirements of seal performance of screw vacuum pump. The study can provide a reference for the design of screw pump rotor and seal structure.