抄録
The effect of lubricant viscosity on the temperature and thickness in oil film on a piston ring in a diesel engine was analyzed by using unsteady state thermohydrodynamic lubrication model. The oil film viscosity was then estimated by using the temperature and the shear rate for multi grade oil. Under low temperature condition, the viscosity becomes lower due to viscous heating and shear rate, and under higher temperature condition, the viscosity affected by the shear rate becomes lower. The oil film thickness between the ring and liner decreases with decrease of the oil viscosity, and it is the thinnest that the oil film thickness is calculated by using the viscosity estimated from both the shear rate and the oil film temperature.
