A Research On Design Of Powertrain-subframe Mounting System

The powertrain-subframe mounting system(PSMS)is one of the most important subsystems in a vehicle,including powertrain,powertrain-body mount,powertrain-subframe mount,subframe and subframe-body mount,The design ability of a PSMS is directly related to the level of a car’s noise,vibration and harshness(NVH).This paper gives an elaborate details for the PSMS,including the optimization of rigid body modes,the method of design of motion control,and the method of calculating dynamic displacements.The contents of this paper are:(1)Based on trifilar torsional pendulum measurement,the center of gravity and the inertia tensor of the powertrain are acquired.The parameters of the subframe are identified by the 3D software,then the center of gravity and the inertia tensor of the subframe are obtained.Those measurement results are the input paramenters of the design and optimization of the PSMS in later chapters.(2)A new 12 degree of freedom(DOF)calculation model which can calculate the displacement of the center of gravity(CG)and rigid mode for the PSMS is established.Then the displacements of the powertrain’ s CG and the displacements of the subframe’s CG and the displacements and forces of the mounts under many quasi-static loads in the PSMS are calculated using this model.The theoretical calculation model is verified by ADAMS model.The calculation results of the 6 DOF powertrain mounting system(PMS)and the 12 DOF PSMS are compared and analyzed,it shows that the necessity of establishing the 12 DOF PSMS model.(3)A dynamic performance calculating model for a PSMS is established.Calculation methods for determining the dynamic displacements of a powertrain’s CG,the dynamic displacements of a subframe’s CG and the dynamic reaction forces of each mount in a PSMS under ground and motor shake excitation are developed in this chapter.Based on this calculation model,an optimization model for the dynamic characteristics of the mounting system is established,the mount dynamic reaction force is the optimization objective function,the mount stiffness is the constraint condition.It provides a useful reference for the development of the PSMS.