| Dry vacuum pump design and development originated in the semiconductor microelectronics industry,mature in medical,machinery,coal equipment,industrial dust removal rust and other industries.Although China has made progress in the vacuum pump industry in recent years,the whole vacuum pump industry is still in the stage of learning from foreign countries.The development trend of the vacuum pump industry in the future is definitely inclined to oil-free clean vacuum pump,oil-free clean vacuum pump has a broad market and demand.However,the oil-free and clean vacuum pump produced in China is of average quality and mediocre reliability,which limits the development of domestic vacuum pump industry to a certain extent.In order to improve the reliability of dry vacuum pump,the structure optimization design and flow field dynamic characteristics of claw dry vacuum pump were studied.Firstly,based on the overall structural design and working principle of the claw vacuum pump,the limit vacuum degree and its influencing factors had been analyzed.From the point of view of sealing and vacuum degree,a claw vacuum pump with motor shaft directly connected rotor had been designed,which completely eliminates the dynamic sealing structure between the pump and the outside atmosphere,and had improved the vacuum degree,reliability and stability of the claw vacuum pump.Starting from the theoretical profile of the rotor,by analyzed the influence of the parameters such as the shape coefficient of the top of the claw,the angle of the center and the meshing clearance on the performance of the rotor and the pump,various parameters had been optimized,and finally a new type of spiral straight claw rotor had been constructed.Secondly,the formula for calculating the compression ratio of claw vacuum pump had been deduced,and the influence of screw rotor on the compression ratio of claw vacuum pump was explored.Combined with the theoretical basis of pump fluid dynamics and rotary positive displacement pump,the theoretical ultimate pressure and practical limit of the claw vacuumpump have been analyzed.Based on the theoretical knowledge of fluid mechanics,the influence of helical straight claw rotor on the flow field had been analyzed,and its superiority has been confirmed.Thirdly,based on the theoretical basis of numerical calculation of the flow field,the governing equation of the internal flow of the claw vacuum pump was selected,and an appropriate turbulence model was selected for the numerical simulation of the flow field of the claw vacuum pump.The flow field of the vacuum cavity was solved by using CFX analysis module.The pressure field characteristics,flow field streamline characteristics and flow field eddy characteristics of the two flow fields were compared in detail,and the beneficial influence of the spiral rotor on the flow field of the claw vacuum pump had been explored.Through the above three aspects of work,the structure of the claw type dry vacuum pump had been optimized.The sealing had been improved,the geometrical parameters had been optimized,the dynamic characteristics of the flow field had been analyzed,and the reliability of the pump had been improved. |
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