Kinematics And Friction Lubrication Analysis In The External Return Mechanism Of Piston Pump/Motor

The external return mechanism is an important mechanism of the balanced double-row axial piston pump and the dual-driving axial piston motor.Its dynamic characteristics and frictional lubrication characteristics have a great influence on the working performance of the pump/motor’s slipper pair,plunger pair and flow distribution pair,and it is also a key factor affecting the service life,performance and vibration noise of the piston pump/motor.Therefore,the external return mechanism the paper is the research object,and the mathematical model of kinematics and friction lubrication characteristics is established,and the relative motion relationship,friction loss and dynamic lubrication mechanism are analyzed.It lays a foundation for the analysis of the energy dissipation law,wear characteristics and mechanical properties of the axial piston pump with external compaction structure and the dual-driving axial piston motor.The main work is as follows:The research background and significance of the balanced double-row axial piston pump/motor external return mechanism and the technical difficulties of the research are expounded.The research status of the friction and wear and lubrication characteristics of the key friction pair and return mechanism of the axial piston pump are reviewed.The structural advantages and development prospects of the external backhaul mechanism are analyzed.The source of the project,the research purpose,and the research content are summarized.The theoretical model of the external backhaul mechanism is established.Based on the external compaction return mechanism of a balanced double-row axial piston pump and the vector coordinate transformation principle,a mathematical model of the relative motion relation within the external return spherical bearing pair was built.The influence of slant inclination of the external swash plate and of pump shaft rotating speed and eccentricity on the relative motion trail,movement speed and acceleration was analyzed.The relative motion velocity and acceleration between external retainer plate and external spherical hinge were discussed.Based on the kinematics of the external return mechanism,the force analysis of the external return,calculate the return force of the external return mechanism and the minimum preload of the compression spring,establish a mathematical model of the frictional power consumption between the external retainer plate and the external spherical hinge,and the spring force of the compression spring,the influence of the pump shaft speed,the incline angle of the external swash plate inclination,and the eccentricity on the frictional power consumption were analyzed.Based on the spatial relative motion characteristics of the external return mechanism,combined with the geometric characteristics and relative motion relationship of the external spherical hinge,the velocity boundary of the lubricating oil film based on the spherical coordinate system is determined.Based on the fluid dynamic pressure lubrication theory,the external return mechanism is derived in the spherical coordinate system.The Reynolds equation and the film thickness equation are used to establish a numerical solution method.