Matching And Optimization Design For Powertrain Mounting System Of Heavy-duty Commercial Truck

With the development of automotive industry automotive and increasing comfort requirements,good NVH (Noise Vibration Harshness) characteristic is a major sign of modern vehicles. Loading vehicles with the purpose of delivering goods, even though the main focus of the methods and ideas of solving NVH problems is to protecting the goods in the past,however, in recent years to ensure that the requirements of crew comfort, such as NVH have become an important evaluation content of the commercial trucks,particularly in the countries whose automotive industry is more developed,people are more willing to select a truck with better comfort,so any manufacturers dare not take it lightly of the occupant's comfort.The excitation source caused vibration of motor vehicles including the road roughness and the imbalance of force moment of engine at the time of work. With the improvement of road conditions and the improvement of the suspension damping system's design, the incentive for the car engine vibration becomes more prominent, reasonably match the powertrain mounting system can reduce the transmission of vibration to the cab so as to improve vehicle ride quality and comfort. Therefore, research on the influence of the vehicle powertrain vibration is very significant.This article is a combination of country "863" research and development projects: " integrated development of advanced technologies of heavy-duty commercial vehicle (2006AA110105)", to study the vibration isolation performance of heavy-duty commercial truck's powertrain mounting system .Main content of this thesis is as follows: First of all, based on a lot of reading at home and abroad, a systematic summary of the development process of suspension components, as well as the domestic and foreign scholars research methods and research results for powertrain mounting system was did. We described the function of powertrain mounting system, analyzed the principle of vibration isolation of powertrain mounting system, gave the rate of vibration's transmission of the powertrain mounting system and the formula for calculating the vibration decoupling, described the significance of vibration decoupling, and compared the advantages and disadvantages of various methods of decoupling. On this basis, using the MSC. ADAMS/View modules and finite element software Hyper Mesh to set up six freedom degrees rigid body model and coupled model of rigid body and elastomer. Then using ADAMS/Vibration module to simulate and analysis the mode of the power system which has been set up, to calculate the natural frequencies, mode shapes and modal coupling of the powertrain model, and to compare those two types of models in the natural frequencies, mode shapes and modal coupling, finally described the importance of the foundation of coupled model between the power train and chassis.Then,optimize the coupled models between the powertrain system and chassis. We did the analysis and calculation with the goal of the powertrain mounting system's decoupling and using the stiffness of the parts comprised of the powertrain mounting system as the design variable. The results show that apart from the decoupling rate of the vibration along the Y-axis slightly decreased, the vibration of the other direction have markedly improved the rate of decoupling, among them,the three main direction roll, pitch and vertical's vibration decoupling rate increased from 60.43% 40.75%, 49.08% before decoupling, to 82.94%,83.62%,71.99% after decoupling,and the system's vibration transmission rate also reduced 9.76%,the performance the isolation of the mount has also improved and achieved good results in optimization.Finally,according to the orthogonal experimental design (DOE) approach, for the target of get the minimum transfer rate of the power device assembly in the direction of roll, select orthogonal array L9(34)to do the powertrain mounting system's optimal design, using the stiffness of the front and rear suspension as the factor. The optimization results show that the program 4 has the smallest vibration transmission rate in the roll direction, when it meets the premise of the three main decoupling rate. So set the suspension parameters of program 4 as the parameters of powertrain. At this parameter, plot the displacement curve of the center of mass on power assembly at three directions of X, Y, Z to verify the amount of its maximum displacement to meet the displacement constraints in, and to compare the acceleration and vibration transmission rate at the Z direction before and after the tests. It shows the feasibility and reasonableness of the determination of make program 4's stiffness as the final parameters of the power assembly.