The Optimization Research Of Engine Vibration Isolation System

Whether the vehicle engine or bench engine, the imbalance force and torque in the process of its work are the man excitation source of the vehicle vibration or the test stand vibration.In the purpose of reducing the vibration transfer from the engine to the support base, improving the ride comfort of vehicle and the working environment of the laboratory, we should design a engine vibration isolation system with a good performance. Taking the single-layer vibration isolation system of a bench engine and the double-layer vibration isolation system of a combustion vehicle powertrain for the object, the following works have been carried out:1).By searching for lots of relevant literatures, the development of the isolation components and the development in the world of the engine vibration isolation system optimization have been analyzed. Taking the basis of the engine as a rigid body, the modeling for the single-layer and double-layer vibration isolation system of engine by dynamic method has been finished.2).By MATLAB software, engine vibration isolation system optimization program what is called "EVISOD" program has been developed. The "EVISOD" program has been verified by ANSYS software and ADAMS software.2).For an engine single-layer vibration isolation system, the inherent characteristics and dynamic response before and after the optimization have been analyzed by "EVISOD". After the optimization, the decoupling of the system has improved significantly, the vibration intensity of the system has reduced significantly, the vibration transmission ratio within the engine operation frequency range of the system has also improved significantly, the reaction forces of each isolator has also reduced. Based on the Monte Carlo method, the affection of the inherent characteristics and vibration intensity and the reaction forces of each isolator at Z way caused by the stiffness deviation have been researched.4).Against a double-layer vibration isolation system, the vibration characteristics of theoretical stiffness program has been analyzed with "EVISOD". Using enumeration method optimization software and decoupling optimization software, the system has been optimized respectively and found that the result of optimized program is closed with the theoretical optimal program.On base of the theoretical stiffness program, the transmission ratio of the powertrain system with single-layer and double-layer have been analyzed respectively. The result showed that the transmission ratio of the double-layer vibration isolation was much smaller than transmission ratio of the single-layer vibration isolation within the frequency range greater than30Hz.The result confirmed that the double-layer vibration isolation system was very superior in the high frequency excitation system. The variation of the vibration characteristics of the powertrain system caused by the first-layer isolators’stiffness ratio "Kx/Ky" and the second-layer isolators’stiffness ratio "Ky" have been studied respectively, and the results have specified a more clear direction of the system’s further optimization. Finally, based on the Monte Carlo method, this paper has studied the affection of the inherent characteristics and the vibration intensity and the reaction forces of the second-layer isolators at Z way caused by stiffness deviation.5).According to the previous design experience, the general design process and key points of the engine vibration isolation system have been summed up with the aim of guiding non-professionals to design a vibration isolation system with excellent performance based on the process and the key points. And the research has a certain degree of engineering guiding significance.