Abstract
We investigated the influence of main-bearing asperity contact on combustion-induced vibration of a diesel engine by simulation. Main findings are as follows: As the viscosity of engine oil is increased, the asperity-contact pressure for a main bearing decreases and thus both vibration-transmission efficiency and decay rate decrease. The contribution of vibration-transmission efficiency to the engine outer-surface vibration is bigger than that of decay rate and thus the engine outer-surface vibration becomes small. Both asperity-contact pressure and oil-film pressure become small if the partial contact to the main bearing by crank-shaft elastic deformation is reduced by properly changing the main-bearing angle. As in the case of an increase in the oil viscosity, both vibration transmission efficiency and decay rate become low, leading to a decrease in the engine outer-surface vibration.
