A Study of Vibration Reducing Effect on Vehicle Dynamics by Hydraulic Damper on Body Structure

This research investigated the mechanism of the effects of hydraulic dampers, which are attached to vehicle body structures and are known by experience to suppress vehicle body vibration and enhance ride comfort and steering stability. In investigating the mechanism, we employed quantitative data from riding tests, and analytical data from simplified vibration models. In our assessment of ride comfort in riding tests using vehicles equipped with hydraulic dampers, we confirmed effects reducing body floor vibration in the low-frequency range. We also confirmed vibration reduction in unsprung suspension parts to be a notable mechanical characteristic which merits close attention in all cases. To investigate the mechanism of the vibration reduction effect in unsprung parts, we considered a simplified vibration model, in which the engine and unsprung parts, which are rigid, are linked to the vehicle body, which is an elastic body equipped with hydraulic dampers. Simulation analysis results revealed that vibration in unsprung parts is reduced by coupling the rigid vibration of the engine and unsprung parts with the elastic vibration of a vehicle body, equipped with hydraulic dampers, in the low-frequency range. The above raises the prospect of achieving optimum specification study of hydraulic dampers by using the simplified vibration model of this research in the initial design stage of vehicle development.