A Study On The Working Characteristics And Internal Flow Field Of A4VG Axial Piston Pump

Axial piston pump as the power component of the hydraulic system is widely applied in engineering machinery and many other fields.Taking A4 VG series axial piston pump as the research object,analysis of working characteristics of axial piston pump,swash plate-slipper pair local wear and piston pump cavitation phenomenon and its suppression measures with different port pair structure are carried out based on the hydraulic principle.Aiming at improving the pressure flow characteristics of piston pump to deal with the complex requirements of operating performance.For the different port plate pairs between spherical port plate and traditional planar port plate,surface modeling technology is employed to establish the geometric model of whole basin piston pump.On the basis of above,the axial reciprocating motion and rotary motion of the cylinder piston cavity are simulated through the moving grid.Based on the Computational Fluid Dynamics(CFD),the whole basin of the axial piston pump is analyzed on the basis of the full cavitation model,analyzing the spherical port plate and planar port plate in the cavitation,outlet pressure and flow pulsation of piston pump,hydraulic support force and torque changes of lubricating film surface.The conclusion is obtained that spherical port pair in flow process is more stable and the stress condition,pressure as well as flow pulsation rate are better than the plane port pair to a certain extent,while the difference of influence to the degree of cavitation can be neglected.Then,the mathematical model of the oil film thickness between swash plate and slipper is established,mechanism of the slipper local wear and the variation of oil film thickness with the piston cavity pressure changes are analyzed.The results show that the local wear occurs mainly in oil expulsion stage and prevent local wear of slipper is very important,because the slipper local wear slope will increase the degree of inclination and the local wear further accelerate,slipper leakage also increased significantly,which will reduce the volumetric efficiency.Finally,for further study the effects of damping groove on the cavitation cloud,the method of theoretical analysis and simulation verification is employed.The process of cavitation bubbles from growth to collapse is studied numerically and effects of common U-shaped groove and V-shaped groove on the cavitation phenomenon are analyzed.It is shown that the cavitation can be effectively restrained to a certain extent by increasing the number of V-shaped grooves or the aspect ratio of the cross section of a U-shaped groove under the same flow area.On the basis of this,a kind of ?-shaped groove integrating the advantages of the U shaped groove and the V shaped groove is proposed.The analysis results show that the new damping groove can largely reduce the erosion caused by the cavitation,improve the volume efficiency and service life of axial piston pump.