Studies on Reduction of Total Friction Loss for Diesel Engine(DEPARTMENT OF MECHANICAL ENGINEERING)

In order to prevent the global warming the improvement of fuel economy for internal combustion engines should be more thoroughly done in both technological fields of the combustion and the tribology. In this paper some experimental study results on the reduction of frictional power loss in a practical diesel engine are described. The total friction loss has been measured by the run-out method for fired and braked engines. The total friction mean effective pressures P_tf changing with the engine speed, load rate and cooling water temperature have been examined for following design factors concerned with the piston system and the engine lubricating oil. The effects of the sliding surface roughness or coating of piston components on the reduction of P_tf are evaluated, followed by those of the engine oil properties, namely lowering the viscosity of single grade oils, applying the low viscosity multi-grade oils SAE10W30 and SAE5W30. Also, the influence of the oil deterioration on P_tf has been examined. Further, the diesel engine oils have been refined to be DL-class or DH-class oils lower in sulfated ash, phosphorus and sulfur contents formulated as Low-SAPS oils to protect the diesel particulate filter and the deNOx catalyst. Therefore, the influences of the Low-SAPS oils like DH-1, DH-2 and other newly developed oils less in additives ZnDTP have been examined. Likewise, the effects of lowering the viscosity of the Low-SAPS oils on the reduction of P_tf are evaluated