Study On Friction And Wear Characteristics And Internal Leakage Of High Pressure Double External Gear Pump Based On Clearance Compensation

Gear pump as a widely used energy supply components in many fields of hydraulic system,has the advantages of simple structure,oil insensitivity and good self-suction.The problems of gear pump such as internal leakage,oil trap and wear limit its application in high pressure system.Therefore,it is of great significance to study the internal leakage law of the gear pump and the friction and wear characteristics of the material to improve its working pressure and service life.In this paper,the theoretical analysis of the optimal end face clearance,the simulation analysis of the internal flow field and experimental verification,the automatic compensation method of the axial clearance,the balance analysis of the floating bushing and the research on the friction and wear of materials are carried out based on the high pressure dual external gear pump.Firstly,the paper introduces the structure and working principle of the high pressure double external gear pump,and analyzes the ways of the internal leakage of the gear pump and its influencing factors.A simplified model of end face clearance leakage flow is established to derive the calculation formula of internal leakage flow,and the optimal axial clearance was solved with the goal of minimizing the total power loss.The theoretical geometric displacement,instantaneous flow,flow pulsation rate and volumetric efficiency of the gear pump are analyzed.The simplified model of the flow field in the gear pump is simulated and the whole process of the pressure balance in the gear pump and the change of the pressure and velocity after the balance in one cycle are analyzed.The simulation results show that the optimal end clearance of the gear pump is 0.0032 mm,and the maximum volumetric efficiency is 82.89 %.The experimental results of the gear pump under different working conditions were compared with the simulation results,so as to verify the feasibility of the simulation method and the reliability of the simulation results.Based on the principle of automatic compensation of axial clearance,the structure and material of each part of the floating bushing are analyzed.A simplified model is established to discuss the stress of the floating bushing,and then the variation of the axial force of the floating bushing with time is obtained based on the simulation method.Simulation results show that the axial compression ratio of the floating bushing is about 1.17,which verifies the rationality of the balance design of the floating bushing.The tribological studies of gear-gear,gear-pump body and gear-floating bushing under oil lubrication were carried out on carburized 30 Cr Mo A gear material,6082 pump body material and Sn-Cu aluminum alloy floating bushing material.The results show that in a certain load range,the wear of the material increases with the increase of load.The friction coefficient of gear pair line contact decreases with the increase of load,which is mainly caused by abrasive wear.The friction coefficient of the linear contact between the gear and the pump body decreases with the increase of the load,and the wear mainly occurs in the pump body material and is abrasive wear and adhesive wear.The friction coefficient between the gear and the bushing surface increases with the increase of the load,and the wear mainly occurs in the bushing material and is adhesion wear.