Research On The Characteristics Of The Plunger Pair Of The All Water Lubricated Axial Piston Pump Under High Static Pressure

Deep sea exploration can not be separated from the support of deep sea hydraulic equipment.The hydraulic plunger pump with compact structure and high efficiency is an important component of the deep sea hydraulic equipment system.The performance of pump directly affects the reliability of hydraulic equipment.In the water lubricated plunger pump,the plunger pair should not only ensure the tightness,but also reduce the movement stagnation and wear,which ensures the precise sealing clearance of the plunger pair.However,in the high static pressure environment,the radial deformation of the plunger sleeve is serious because of the deep sea seepage pressure.Under the action of complex alternating load,the precision seal clearance is deformed and misaligned,which makes the clearance smaller or even disappear,causes the plunger pair to be stuck,aggravates the wear,and even causes the plunger pump to be stuck.At the same time,in the high static pressure environment,the O-ring of the plunger assembly is continuously squeezed and occluded during the working process,which frequently leads to the seal failure.Therefore,it is very important to study the deep sea pressure permeability characteristics,the sticking characteristics and the failure characteristics of O-ring seal of the plunger pair of the all water lubricated axial piston pump under the high static pressure environment.In this paper,three characteristics of plunger pair and its components are studied.First of all,the penetration characteristics of the deep sea pressure of the plunger sleeve / cylinder are analyzed,and the penetration characteristics of the deep sea pressure of the plunger sleeve are obtained,which provides the basis for the research of the piston pair’s stuck characteristics.Secondly,the characteristics of piston pair’s stagnation under high static pressure are studied: according to different sea depth and different water injection and drainage conditions,the dynamic curves of contact stress,equivalent stress and PV value of plunger sleeve and plunger under different conditions are calculated by fluid structure coupling simulation model,which provides theoretical basis for the phenomenon of piston pair’s stagnation and wear.At last,the main reason of the failure of O-ring is determined according to the research of the dynamic extrusion and engagement failure characteristics of the O-ring.Through this study,it is found that when the single side interference between the plunger sleeve and the cylinder block hole is 0.01 mm,and the sea depth is more than 300 m,the sea depth pressure penetration occurs on the plunger sleeve / cylinder block interference fitting surface,which changes the load state on the outer surface of the plunger sleeve.To ensure that when the working sea depth of the plunger pump is 1500 m,the interference fitting surface will not have sea depth pressure penetration,and the single side interference should not be less than 0.05 mm.At the same time,when the single side interference is 0.01 mm and the sea depth is more than 600 m,when the plunger pump carries out water injection and the plunger is located in the water pressure area,the PV value of the plunger pair has exceeded the allowable value.In addition,through the analysis of the failure of Oring of the plunger assembly,it is found that the equivalent stress increases with the increase of the swing clearance,which proves that the excessive swing clearance is the main reason for the failure of O-ring.