Optimization Design Research And Software Platform Development For Two-Stage Vibration Isolation System Of Powerpack In Diesel Motor Car

As a kind of power machine, the internal combustion engine is widely used in all aspects of life and production because of its strong maneuverability, high output power and good economic performance. However, the internal combustion engine in the running process will produce large imbalance force and torque, causing strong vibration in engine and surrounding equipment. Especially when a high-power diesel engine is used in the diesel motor car, the vibration caused by diesel engine will exacerbate the vibration and noise condition of the vehicle, and seriously affect the stability of working parts and the riding comfort of passengers. So it is necessary to carry out vibration isolation design for the powertrain of the diesel motor car, to prevent the vibration from transferring to surrounding equipment and to reduce the adverse effects of the vibration on the whole system.At present, the most commonly used method for the vibration isolation of the powertrain of the diesel motor car is two-stage vibration isolation system design. Enumeration method is usually applied to the parameter optimization design of vibration isolation system, and the optimization objective is just one vibration isolation performance index of the vibration isolation system. This optimization method, with huge computation load and low efficiency, fails to take into account other vibration isolation performance indexes. Therefore, it is essential to select a new type of optimization algorithm, which can be used in the multi-objective optimization analysis for the two-stage vibration isolation system, thus comprehensively considering the vibration isolation performance of the system. In addition, when using ADAMS, ANSYS and other traditional vibration analysis software, the optimization calculation is cumbersome, resulting in low efficiency and accuracy. So it is necessary to develop the vibration calculation and parameter optimization software, specifically for the powertrain of the diesel motor car to improve the design efficiency for vibration isolation.On the basis of the above discussion, this paper makes a deep research on the optimization design for two-stage vibration isolation system of the powertrain of the diesel motor car.In this paper, the influence of the stiffness parameters of the first and secondary stage isolators of a two-stage vibration isolation system on the system’s vibration characteristics was analyzed, including the influence of the vertical stiffness, the ratio of longitudinal and vertical stiffness, the ratio of lateral and vertical stiffness of the first and secondary stage isolators on the mode frequency, the unit’s vibration intensity and the dynamic reaction force of the isolators. On the basis, main influence factors of these vibration isolation performance indexes and the optimization direction and range of the isolator stiffness parameters are identified, thus providing reasonable variable constraints for the optimization design to improve the computational efficiency and accuracy.A multi-objective optimization mathematical model was established for the two-stage vibration isolation system of the power assembly, and the optimization objective, the optimization variables and the constraint conditions were determined. On the basis, by using the calculation and optimization program, the multi-objective optimization calculation of the stiffness parameters of the isolator was carried out. In the process of optimization calculation, the decoupling degree, the dynamic reaction force of the isolators and the unit’s vibration intensity was taken as the optimization objective and the multi-objective genetic algorithm based on Pareto efficiency was chosen as the optimization algorithm.In order to guide the engineering staff to design the vibration isolation system efficiently and reasonably, a software platform for the analysis and optimization of vibration isolation system was developed, which was named as DVIS. The software platform can carry out the calculation of the excitation characteristics of the internal engine and the generator to determine the vibration isolation design requirements, and the free vibration and forced vibration analysis to evaluate the vibration isolation performance of the system, and the optimization design of vibration isolator stiffness parameters to improve the system’s overall vibration condition. Finally, the software platform was applied in the vibration isolation design of the power assembly of a diesel motor car. The results show that the software platform has the characteristics of complete functions, simple operation, accurate calculation and reliable operation, which can greatly improve the efficiency of vibration isolation calculation and optimization design, and has high engineering application value.In summary, the work of this paper can not only provide design ideas for powertrain vibration isolation design, and provide an efficient and practical engineering application tool and analysis platform for the vibration isolation design, but also has some reference value for the vibration isolation design of other equipment.