Research On Sealing And Lubrication Performance Of Plunger In High Pressure Common Rail Pump

Plunger matching parts is one of the precise coupled parts of high pressure common rail system.Under the mutual influence of the plunger cavity fuel pressure,spring force and CAM radial force interaction,plunger produces deformation that leads to the change of its fuel leakage and lubrication performance,causing the decreasing sealing and lubrication performance and the wear and tear of plunger matching parts.Plunger matching parts is the source of the high pressure common rail system's pressure,so its Sealing and Lubrication Performance has an important influence on improving the injection pressure of high pressure common rail injection system.On the basis of introducing the operation characteristics of high pressure common rail fuel injection pump,such as working principle,sufferance force and movement,and with combining the fluid lubrication and tribology theory,this paper analyses the mechanism of sealing and lubrication of the plunger matching parts,and acquiring characteristics of sealing and lubrication of the plunger matching parts.With simulation of the clearance oil film by Fluent software,this paper analyses the influence of the seal characteristics of the plunger matching parts and parameters of pump working characteristics and the characteristics of fuel.Heat-fluid-solid coupling simulation of the plunger matching parts used by ANSYS Workbench indicates that the thermal load on the plunger matching parts clearance has great influence on characteristics of plunger matching parts.Simulation analysis of the change rule of oil film distribution gap under the different fuel temperature,found that the higher the temperature,the greater impact on the deformation of clearance.At the same time,the simulation analyses the deformation of the oil film thickness influenced by radial stress under different pressure,and determines the wear position of the plunger matching parts by the oil film thickness deformation.In purpose to improving the characteristics of seal and lubrication of plunger matching parts,this paper puts forward four methods on machining cylindrical compensation hole in the top of plunger end.With analysis,comparison and simulation results,we found that inserting compensation hole in top of plunger end and replacing plunger's material to ceramic can improve the sealing and lubrication of the plunger matching parts performance.Electron microscopy(sem)observations found that the wear parts of the plunger matching parts is relatively concentrated,mainly in the upper part and the bottom of plunger sleeve which is 2mm far from the top surface and 2.5mm far from the bottom surface ofplunger,these locations exactly concentrated when plunger on the top and bottom stop position,the contact position between the plunger end face and the plunger sleeve surface,and the position of the plunger end face and the plunger surface.And the most serious wear part is nearly the top face of plunger,and there are traces of adhesive wear.The study of parameters affecting the lubrication characteristics of plunger pump has indicated that the biggest influence on the plunger's lubrication characteristic parameter is the working pressure of fuel injection pump,the followed is the fuel injection pump rotation speed and the amount of oil pump have little impact.Combining simulation and test,found that machining compensation hole and replacement of ceramic material is useful to improve sealing and lubrication characteristics of the plunger matching parts.