The Design And Analysis Of Caned Motor Used On Ultra Clean And Corrosion-Resistant Scroll Vacuum Pump

At present,the vortex vacuum shield pump is infrequent in our country relatively.The pump and the motor of traditional structure are sealed with bearing mechanically,so the leakage rate is higher.When the scroll vacuum pump is used to transport toxic and harmful media,it is easy to pollute the working environment.Firstly,the design features of the canned motor for 4L scroll vacuum pump are summarized.Based on the Ansoft software aided design,this paper presents the electromagnetic design procedure of canned motor.Two sets of electromagnetic schemes are designed for the Sus321 shielding sleeve and the Sus430 shielding sleeve.The similarities and differences between the two kinds of shielding materials used in the electromagnetic design of the motor,and the influence of the shielding material on the working performance of the motor are analysed.Secondly,the modeling and analysis of temperature field of this two sets of electromagnetic scheme was made with Solidworks and Ansys Workbench,assuming that the air gap is a absolute vacuum approximately,considering the effect of thermal radiation shielding inner surface and the outer surface of the rotor sleeve.The temperature distribution of each part of the motor is simulated.The winding temperature of this two sets are both slightly higher than the design requirements.The overall temperature of Sus430 shielding sleeve scheme is smaller than that of Sus321 shielding scheme.After the forced convection is adopted,the temperature of each part of the motors meets the design requirements.Then,the stress field is calculated by the coupling of the calculation results of the steady temperature,obtaining the thermal deformation and thermal stress distribution characteristics of the two kinds of schemes.Combining the above analysis results,this two sets of design scheme can meet the design requirements,the armature current,starting torque,maximum torque,efficiency,power factor and temperature performance of Sus430 shielding scheme is better,Sus321 shielding scheme is more suitable for the transmission of strong corrosive mediaFinally,a simplified model of the shielding motor is established,and the two kinds of heat transfer in the air gap,the thermal radiation and heat conduction of rarefied gas are analyzed.The simplified model analysis shows that he first heat radiation plays a major role with the vacuum changing from by close to absolute vacuum to a standard atmospheric pressure.With the air pressure increasing,the thermal conductivity increases.The heat flux caused by air heat conduction increases,and heat flux caused by thermal radiation decreases.The variation of total heat flux increases,and the temperature difference of two surface decreases.In the analysis of the temperature field of vacuum canned motor,when the inner surface of the shield is used as the adiabatic surface,the heat transfer between the inner surface and the outer surface of the rotor core is relatively large,the heat transfer in the air gap should be considered.