Optimization Methods to Enhance Performance of a Powertrain Mounting System at Key on and Key off

To enhance the transient vibration performance of the vehicle at key on and key off, a method for optimizing mount parameters of a powertrain mounting system (PMS) is proposed. Uncertainties of mount parameters widely exist in a PMS, so a method for optimizing mount parameters of a PMS, which treats the mount parameters of a PMS as uncertain, is also proposed in this paper. Firstly, a 13 degrees of freedom (DOFs) model including car body with 3 DOFs, a PMS with 6 DOFs and unsprung mass with 4 DOFs is established, and the acceleration of the active side of mounts is calculated. An experiment is carried out to measure the accelerations located at active and passive sides of each mount and the accelerations of seat track. A comparison is made between the measured and estimated accelerations, and the proposed model is validated. Two optimization methods for the PMS are proposed based on the developed 13 DOFs model. One method treats mount parameters as deterministic variables, while another one treats them as interval variables. Vibration dose value (VDV) of longitudinal acceleration of a powertrain is defined as one of optimization objectives, and natural frequencies (NFs) placement and energy distributions of a powertrain in different directions are also defined as optimization objectives. The ranges of powertrain uncertain responses are obtained through the perturbation center difference method (PCDM) and are validated using the Monte Carlo method (MCM). The optimized upper and lower bounds of powertrain responses are also given. Finally, key on/off experiments with optimized mount parameters are carried out to validate the proposed methods.