Abstract
In order to study the frictional lubrication characteristics of a piston pump under varying loads and speeds in actual work, mathematical models, such as a cylinder dynamics model, cylinder micro-motion model, and external return spherical bearing pair lubrication model, were established under full working conditions. The influence of different parameters on the lubrication characteristics of the external return mechanism under full working conditions was analyzed. The results show that in a working cycle, when the pump was at low working pressure, the maximum value of the maximum oil film pressure increased with an increase in the cylinder block speed, which is basically consistent with the ideal conditions. With an increase in the working pressure, the maximum value first decreased and then increased with an increase in the cylinder block speed. When the cylinder block speed was constant, the total friction power increased with an increase in the working pressure and the internal as well as external swash plates’ inclination; considering the contact surface roughness of a friction pair under full working conditions, the total friction power increased by 46.8% compared with the ideal working conditions. The axial leakage flow increased with an increase in the external swash plate inclination and remained unchanged with an increase in the internal swash plate inclination. This research is beneficial for improving the lubrication theory of the external return mechanism and lays a foundation for improving its working performance.
Highlights
The return mechanism is an important part of a piston pump; it is the connection device of the three key friction pairs of a piston pump
During the operation of a piston pump, on the one hand, the return mechanism provides the preload of the slipper pair and port pair to ensure that the cylinder block, port pair, and slipper pair are in a floating state, so that the slipper pair and port pair can achieve the best oil film thickness of the hydraulic static balance
Zhang et al [12] constructed a rigid–flexible coupling dynamics model of a piston pump based on ADAMS and ANSYS, and simulated and analyzed the force law of a return plate and the factors affecting the force state
Summary
The return mechanism is an important part of a piston pump; it is the connection device of the three key friction pairs (i.e., slipper pair [1,2], plunger pair [3,4], and port pair [5,6]) of a piston pump. According to the working principle of the external return spherical bearing pair of a balanced double-row axial piston pump, the external return spherical bearing pair is related to the movement of the cylinder block, the pressure fluctuation in the plunger cavity, and its dynamic characteristics. A mathematical model of the external return spherical bearing pair under full working conditions should include a pump motion mmcyoolddineedll,,epcrylbulilnnogdcekerrdcbyhlnoamackmbdiecyrsnomailmopdirceesls,mseuxortdeeermln,oaedlxreteel,truanrnandl rsoepithluefrirnlimcsaptlhhbieecrkaicrnaienlsgbsepeaaqriuirnalgtuiobpnrai.icraltuiobnricmaotidoenl, plunger chamber oil pressure model, and oil film thickness equation. Machines 2022, 10, x FOR PEER REVIEWFormula (5): external rows of the plunger chamber of a balanced double-row axial piston pump are the same, and the change in the oil hydraulic pressure in the plunger chamber is shown in. Where AD is the oil action area of the plunger cavity
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