舶用エンジンのシリンダとピストンリング間の潤滑

抄録

Internal combustion engines have been strongly required to have greater fuel economy and lower exhaust emissions. The thermal efficiency of an engine can be improved by reducing the mechanical friction loss. The friction loss of piston assembly accounts for about 40% of total friction loss. A theoretical analysis is presented of the mixed lubrication between the cylinder and piston ring pack in a small size 4-stroke cycle diesel engine. The analysis comprises Patir and Cheng’s average flow model and Lee and Ren’s asperity contact model. The former decides the hydrodynamic film pressures and the latter estimates the contact pressure and the real contact pressure. Influencing factors such as surface roughness, lubricant viscosity, ring tension and sliding surface profile of top ring on the characteristics of film thickness, friction and lubricant transport are discussed.