Tribology Design Of High Power Diesel Engine Piston

The piston in engines bears great mechanical and thermal loads under extremely strictenvironment, and it is one of the most key fits which affects the durability and efficiency ofengines. Nowadays the frictional design of pistons faces higher requirement than before dueto the deterioration of its working condition with engine intensified incessantly. Therefore,it is very of necessity and significance for engine performance to accurately predict themixed lubrication, on which new piston design standard could be based. In this paper thefrictional design of piston was studied, with the main contents listed as follow.1. Piston thermal expansion was accurately predicted with infrared telemeasurementand finite element analysis.2. Piston second-order movement was studied considering both thermal and elasticexpansion, and curve design standard for piston head was suggested. Meanwhile, pistonsecond-order movement in engine with pin offset was studied, showing that pin offset willincrease piston swing, although the lateral force was reduced, and it will also elevate the oilconsumption.3. Piston second-order movement and mixed lubrication under different configurationof piston skirt curves was studied with methods couping kinetics ofdeformable multi-bodywith mixed lubrication. In addition, evaluation standard for piston skirt curves wasestablished with weighted coefficient method, and the optimization design method was putforward based on orthogonal design technique. In our evaluation model, the wear of pistonring groove, hydrodynamical lubrication and firtional wear, piston swing, and pistonsidewise velocity and acceleration were all taken into account, and last the effect ofdifferent configuration of skirt curves towards piston second-order movement and mixedlubrication was summaried.4. The influence of different surface morphology to piston mixed lubrication wasinvestigated, and morphology from turning and electrolysis was especially considered. Itwas shown that minus skewed character contributed to the mixed lubrication.5. The optimization design method author suggested was applied to design the piston for highly intensified engines. Experiments showed our newly designed piston outlived500hours in endurability test, validating our new design method in this paper. It was alsoshown from the test that deformation of piston skirt occurred in the long term application,resulting in deterioration of mixed lubrication.6. The application of titanium alloy in piston was studied, including its advantage,bottleneck, and solutions. Solutions towards anti-wear of titanium alloy were suggested,and the wear life prediction model was established for piston ring groove. The wear life oftitanium alloy piston coated by ECC film was evaluated with our new model and wear test.