Effect Of Cylinder Liner Deformation On Diesel Engine Piston Dynamics, Oil Consumption And Leakage

As one of the most important friction pairs, the performance of the liner/piston/piston ring system relates with the emission and noise of the internal combustion engine. The study on influence of liner deformation on the dynamic characteristic of piston group can provide some guidance for the optimization design of the friction pair.A naturally aspirated diesel engine was chosen as the research object. The research contents of this paper are as follows. Build up piston group dynamic characteristic model and compare the simulation result with the experiment one. Study on the influence factors of cylinder liner deformation and give the law of the liner deformation. Study the variation laws of dynamic characteristic of piston group, lubrication oil consumption and blow-by with different liner deformation.The results show that:(1) In the process of diesel design, thickness of cylinder liner, positioning shoulder end angle of cylinder liner and bolt-hole depth are chosen properly for reducing deformation of cylinder liner. Bolt pretightening force of cylinder head, combustion pressure and thermal load all contribute to liner deformation, and thermal load is the most influential one.Along cylinder axis, variation laws of radial deformation on characteristic line at angle of0°、90°、180°、270°were concluded. The research shows that the expansion deformation appears in characteristic line at angle of0°,180°,270°and the contraction deformation appears in characteristic line at angle of90°(2) For piston radial displacement, the cylinder liner deformation in the distance range of10mm from cylinder top surface has little influence on the piston displacement peak. With the increase of the range, the effect on piston radial displacement peak increases gradually. And whether the design is3-order deformation or4-order deformation, it will not affect the position of displacement peak.The influence of the4-order deformation design on piston titling angle peak is bigger than that of3-order deformation on the piston titling angle peak. And the effect increases as the deformation design range is better, but it has a little effect on the piston inclination angle displacement peak position. It can say that in the design equal range, the increasing deformation order can cause the piston titling angle peak increases.(3)The design has big effect on the oil consumption when the liner deformation is designed as3-order deformation at a distance about20mm from cylinder top surface or as4-order deformation at a distance in the range of10mm-20mm from cylinder top surface, it has the biggest effect on oil consumption. In the same range from cylinder top surface, the gas flowing in the crank case and the friction loss in the cylinder/piston/piston ring friction pair shows increasing trend with the deformation order increases.