| The powertrain mounting system (PMS) is one of the most important subsystems in avehicle. The design ability of a PMS is directly related to the level of a car’s noise, vibrationand harshness. This paper gives a very elaborate details for the transversely mountedpowertrain system, including the layout design of a PMS, the optimization of rigid bodymodes, and the method of calculating displacements. The contents of this paper are:(1) The layout design for the transversely mounted powertrain system is discussed indetails and the position of mounts are fixed based on the torque roll axis. Then theoptimization model of rigid body modes for a PMS is built. The object function and theconstraints in the optimization are set up. After the stiffness of mounts are optimized, therobustness of the PMS is analyzed based on the theory of probability.(2) Based on the optimization of a single PMS, a calculation method for designing PMSwith multi-powertrains is presented. One powertrain is classified as a basic powertrain and theremaining powertrains are defined as extended powertrains. An optimization method forselecting mount stiffness and location based on the requirement for natural frequenciesplacement and energy distributions for each PMS is developed. Then the method of designingforce versus displacement relation for each mount based on motion control of powertrains isproposed.(3) A method for calculating powertrain and mount displacements in a PMS with torquestruts is presented. A new mount model that is simplified as three linear and three torsionalstiffness in three perpendicular directions is built and used in calculating displacements in thispaper. Also the torque strut is a generic construction and is regarded as a rigid body with twomounts or bushings in its two ends. The method is verified with examples and can be used todesign force versus displacement of mounts more accurately in a PMS with torque struts.(4) Under the road excitation, the model including the tire, unsprung mass, suspension,body and PMS are built in this paper. This model has13degree of freedoms. The vibrationequations of this model is derived. Therefore the mass matrix, damping matrix and stiffnessmatrix are obtained. The model is used to verify that the hydraulic engine mount can controlthe vibration of powertrain and body efficiently due to the road excitation.The methods and theories described in this paper for transversely mounted powertrainsystem can provide a useful reference for the design of a PMS. |
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