Research On Flow Pulsation Characteristics Of Straight Line Conjugate Internal Meshing Gear Pump

The instantaneous flow pulsation of the gear pump is its inherent property.The combination of flow pulsation and system loop impedance will cause system pressure pulsation and even system vibration,which not only affects the stationarity and performance of the operating units,but also haves fatigue and destructive effects on the components that make up the hydraulic system.Simultaneously flow pulsation is still the main source of fluid noise.In view of the problems caused by the flow pulsation of gear pump,this paper first introduces the purpose and significance of the research,and analyzes the research status of internal gear pump and straight line conjugate internal meshing gear pump and the development trend of straight line conjugate internal meshing gear pump.The flow pulsation of the actuators,control elements and auxiliary components in the hydraulic system and the suppression method of the flow pulsation of the hydraulic pump are explored.Secondly,the instantaneous flow analysis method and flow quality evaluation standard of hydraulic pump are introduced.Based on the volume change method,a general mathematical model of the theoretical instantaneous flow rate with the position of the meshing point and the change of the gear angle is established.The maximum instantaneous flow rate is analyzed by the digital combination method.The expressions of the gear transmission’s coincidence degree,theoretical flow rate and flow non-uniformity coefficient are derived.Thirdly,a straight line conjugate internal meshing gear pump produced by Bucher Company is taken as the research object.Based on MATLAB software,the influence of coincidence degree on the theoretical instantaneous flow rate is analyzed.The change laws of structural parameters of the gear pair on the theoretical instantaneous flow rate and flow non-uniformity coefficient are studied.In addition,the main physical and chemical properties of the hydraulic working medium are introduced and the influence of pressure and temperature on it is analyzed.Integrating with the main performance parameters of the research object and the related factors limiting the working pressure and speed of the hydraulic pump,the spindle speed and the range value of working pressure are determined.In addition,the instantaneous flow curves corresponding to different oil properties and operating parameters were calculated without considering the gap leakage.The law of change the maximum flow rate,average flow rate and flow pulsation rate with the viscosity grade,initial gas content,spindle speed,working pressure are compared.Finally,the gap leakage path of Straight line conjugate internal meshing gear pump is analyzed.Considering the combination of axial leakage gap,axial and radial leakageclearance,the instantaneous flow curves corresponding to different gap values are calculated,respectively.The law of change of maximum flow rate,average flow and flow pulsation rate,volumetric efficiency with different gap values are compared.