| External gear pump is a kind of hydrostatic power component,it is widely used in mechanical engineering,vehicle transportation,petrochemical industry and other fields with the advantages of simple structure,strong antipollution ability,well self-priming ability and low cost.With the development of machining and producing technology,the disadvantages of external gear pump have been improved,which plays a more important role in the aircraft hydraulic system,so more stringent performance requirements such as high-speed,lightweight and so on will be put forward for gear pumps.In this paper,the purpose is to develop a miniature external gear pump.According to the performance index given by the subject,the corresponding measures are put forward.Based on this,the parameter calculation,structural design,static characteristics analysis of the parts,the theoretical analysis and simulation research of the friction performance and flow field characteristics of the friction pair are carried out,and the performance test of the prototype is carried out.The involute theory is used to get the gear tooth profile equation and meshing curve.According to the performance requirements,the basic parameters of the gear are determined and the tooth shape is modified.The meshing situation of the gear is analyzed,and the influence of the mechanical efficiency and the outlet pressure on the maximum contact stress of the gear meshing is obtained.For the structural design of floating shaft sleeve of important parts,the measures to solve cavitation,balance radial force and bearing lubrication are put forward.The 3D models of gear pair,pump body and floating shaft sleeve of gear pump are established by Solid Works software,and the static analysis,strength check and modal analysis are carried out by ANSYS Workbench software.Four main friction pairs in gear pump are studied.Based on the principle of hydrodynamic lubrication,this paper analyzes the influence of the speed and load of gear pair on the state parameters,obtains the elastohydrodynamic lubrication state and oil film thickness of gear mesh under rated working condition;obtains the best radial clearance and axial clearance according to the power loss caused by leakage,selects the material with better friction performance through the friction and wear test comparison;selects the bearing type and Check the bearing capacity of sliding bearing under different lubrication conditions.The three-dimensional model assembly of gear pump is established and interference inspection is carried out to obtain the three-dimensional model of internal flow channel of gear pump.By using the software of pumplinx to analyze the flow passage,the effects of inlet size,axial clearance,rotating speed and outlet pressure on the flow field pressure distribution,flow rate,volumetric efficiency,liquid pressure and cavitation degree of the pump are studied.The micro external gear pump prototype test is carried out,the parts are processed and assembled,the gear pump performance test-bed is designed and built,the feasibility of theoretical design and software simulation is verified,the gear pump prototype can meet the performance requirements,and the actual working performance of the gear pump is obtained. |
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