Design method for a powertrain mounting system to decrease the vehicle key on/off vibrations

Five dynamic response evaluation indices from the viewpoint of the powertrain mount system and the vehicle system during the vehicle key on/off periods (i.e. the engine start and stop) are proposed. By analysis using different methods to minimize the powertrain vibration, it was found that an increase in the mount system damping can decrease the vehicle key on and key off vibration. For this reason, in this paper a semi-active hydraulic damping strut is designed and made which can provide high damping for a mount system when the vehicle key on/off but switches to lower damping to isolate high-frequency vibrations under normal conditions. The calculated longitudinal acceleration of the powertrain, the jerk of the powertrain, the dynamic force of the mount and the vibration dose value for a vehicle with the semi-active hydraulic damping strut and without the semi-active hydraulic damping strut are compared on the basis of the excitation force identified for the powertrain using a 13-degree-of-freedom vehicle model. Experiments were carried out, and the results show that the use of the semi-active hydraulic damping strut can decrease the engine start and stop vibrations to a large extent. Finally, the experimental results are compared with the calculated values from the 13-degree-of-freedom vehicle model.