The Design And Optimization Of Powertrain Mounting System

After considerable development, auto industry began to pay more close attention to the quality of the car especially the riding comfort. NVH(Noise Vibration and Harshness) issues becomes one of the most important indicator of a car brand under such a circumstance. Research shows that mounting system is a key factor of the NVH. By optimum design of the powertrain mounting system, the vibration transmitted from the engine to the vehicle body can be effectively reduced, which is benefit to improve the NVH performance of the vehicle.Firstly, the theory and design method of V-type engine mounting system which is mainly used in the longitudinal engine are presented. The sources and frequency components of the excitation force from the powertrain are analyzed. Taking the V-type engine mounting system as an object, the application of torque shaft decoupling theory in the design of V-type engine mounting system is presented. An optimization model of V-type engine mounting system is established. Taking the natural frequency and decoupling rate as objective, the stiffness and the installation angle of the mounts are optimized. A case of an optimization to a longitudinally four-cylinder engine’s mounting system is presented.Secondly, the actual design process and methods of the mounting system are introduced and analyzed with the actual case. In the part of design of the linear stiffness of the mounts, the actual design program is presented. In the part of design of the nonlinear stiffness and position limit of the mounts, the actual design results of 28 kinds of working conditions are presented. In the part of design of the structure of the mount bracket, the strength finite element analysis method is presented as while as an actual analysis example.Finally, to evaluate the effect of the design method, an actual mounting system design case is presented as while as the actual test result. The mainly test method is elaborated. And the equipment used and the common test conditions are introduced. The main evaluation index and its meaning in the test is analyzed. Based on the test vehicle, different stiffness programs are evaluated with the test results compared and analyzed.