| Permanent magnet synchronous hydraulic motor pump is a new type of electrohydraulic power unit integrating permanent magnet synchronous motor,hollow shaft centrifugal pump,internal gear pump and other components.It has the advantages of wide speed range,high power density,high efficiency,low noise,no external leakage and so on.Heat dissipation is one of the main reasons limiting the miniaturization and high speed of hydraulic motor pump.The internal high temperature environment has a great impact on the life of motor winding insulation material,permanent magnet performance,oil viscosity,bearing and seal reliability.In order to solve the above problems,this paper firstly combined theoretical analysis and fluid-structure coupling heat transfer simulation to obtain the temperature field characteristics of permanent magnet synchronous hydraulic motor pump.Secondly,by measuring the temperature distribution of internal gear pump,the temperature distribution law of oil film in the clearance of friction pair of gear pump was obtained,and the rationality of the simplified method of gear pump model in the simulation of the whole domain temperature field of motor pump was verified.Finally,based on the simulation of fluidstructure coupling heat transfer in the whole temperature field of motor pump,the mechanism of liquid cooling enhanced by hollow shaft centrifugal pump was revealed,the shell structure of motor pump was optimized,and the liquid flow and air flow combined heat dissipation method of motor pump was proposed.The main research contents and conclusions are summarized as follows:(1)Taking the heating parts of the motor and the oil film of the gear pump as the heat source of the motor pump,and taking the electromagnetic loss of the motor,the oil viscous friction and the internal leakage power loss of the gear pump as the heat source,the temperature field characteristics of the permanent magnet synchronous hydraulic motor pump were simulated and analyzed.The results show that the local high temperature position of the permanent magnet synchronous hydraulic motor pump is 33.33℃ higher than the end of the motor winding at the end face of the pinion.The temperature rise of working medium of motor pump is mainly caused by leakage and viscous friction in hydraulic pump.(2)The temperature distribution of the oil film in the end friction pair clearance of the internal gear pump was obtained by using the thermocouple embedded temperature measurement method,and the temperature field of the gear pump was simulated.The results show that the pinion end face temperature is lower than the ring end face;The temperature of pinion and ring tooth end face is lower than that of spoke end face,and the temperature difference between tooth end face and spoke end face increases with the increase of rotational speed,but decreases with the increase of load pressure.The maximum deviation between simulation and test results is 5%,which verifies the rationality of the simplified method of gear pump model in the whole domain temperature field simulation of motor pump.(3)The mechanism and effect of enhancing liquid cooling by hollow shaft centrifugal pump were simulated and analyzed.It is found that under the action of centrifugal pump,the liquid flow in the hollow shaft is spirally flowing to the suction chamber of the hydraulic pump.The higher the centrifugal pump speed is,the larger the axial flow and rotation velocity component of liquid flow is,and the better the cooling effect is.Under rated working conditions,the hollow shaft centrifugal pump can reduce the temperature of the components of permanent magnet synchronous hydraulic motor pump by 9.87℃ at most.(4)The shell of motor pump was optimized,and the liquid flow and air flow combined heat dissipation method of hydraulic motor pump was proposed.The results show that the combined heat dissipation method can reduce the temperature of the components of permanent magnet synchronous hydraulic motor pump by 19.27℃ at most under rated working conditions. |
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