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In recent years, although experiment technologies on real engines and simulation technologies has been improved rapidly, the tribology contributing factors have not been quantitatively well evaluated to reveal critical lubrication failure mechanisms. In this study the oil film thickness of the main bearings in multicylinder diesel engines was measured, and the data was analyzed using response surface methodology, which is a statistical analysis methods used to quantitatively derive the factors affecting oil film thickness and the extent of their contribution. We found that the factor with the strongest effect on minimum oil film thickness is oil pressure. Lastly, as a verification test, bearing wear on the main bearings was compared under various oil pressure conditions. Clear differences in bearing wear were identified.

The effects of CO2 and N2 mixing and the effect of O2 concentration on intermittent spray combustion were examined experimentally under the same condition of ambient temperature and pressure, and the same injection pressure. Through the systematic experiments, it was confirmed that the O2 concentration is the dominant factor affecting ignition delay and combustion duration. The flame temperature becomes lower with the decrease of O2 concentration mainly due to the dilution effect. The decrease of flame temperature due to the dilution effect and that due to the thermal/chemical effect of CO2 was quantified. Concerning the soot production, with the decrease of O2 concentration, it is suppressed during the early stage of combustion, however it becomes higher in the middle to later stage of combustion.

In order to study the effects of EGR on diesel combustion fundamentally, the effects of CO2 and N2 mixing into ambient air on intermittent spray combustion were examined experimentally. Under the same condition of ambient temperature and pressure, and the same injection pressure, the rates of CO2 or N2 mixing were changed from 0 to 15% and the combustion characteristics of diesel spray were examined. Through the systematic experiments, it was explored that the ignition delay and the combustion period became longer with the increase of CO2 and N2 mixing, and the effect was larger in the case of CO2 mixing. The flame temperature became lower with the N2 mixing mainly due to the dilution effect. In the case of CO2 mixing, the flame temperature decreased notably, and the flame region with higher temperature became very small. The reason of this tendency was attributed to the dilution effect, the higher heat capacity of CO2 and the chemical effect of CO2.

The New U.S. Evaporative Emission Regulations, which set forth the level of hydrocarbon evaporation generated from vehicles, have been applied in the industry since 1994. In order to meet the Regulations, the filler hose is required to be made for a one tenth of the gasoline permeability of that for conventional filler hose, without design change. The fuel filler hose must also provide a flexible configuration, such as a bellowed or a complicatedly curved shape In order to cope with the problems above, the Author, et al, have successfully developed A LOW PERMEATION FUEL FILLER HOSE which has a high freedom of configuration. During the first stage of development, the Author, et al, developed a hose of 2-layer structure using FKM rubber for inner layer as the permeation barrier, which is applicable in the bellow shape, by means of a unique molding technique.