Powerplant Mount System Vibration Isolation Study

With the developing of science and technology,people's requirement on the riding comfort of automobiles is increasing,and nicer smoothness and low noise are an important symbol of present-day automobiles.Powerplant is one of main vibrations which often result in passenger's uncomfortable.The optimal capability of designing a mount system of powerplant has directly an influence on automobile's smoothness and reducing noise.Hydraulic mount can connect the engine with the chassis of vehicle,it's primary function is to support the weight of the engine;More important function is to isolate the driver and passenger from both vibration and noise generated by the engine.In order to prevent the powerplant from damaging,the mount should keep the engine at the design location in the condition of car driving on uneven road,speeding up and down suddenly and swerving.So it's valuable to design high performance hydraulic mount.This dissertation takes the powertrain of light bus Transit and its hydraulic damped mounting(HDM) system for the study.Firstly,based on the analysis of hydraulic mount's structure,ideal dynamic characteristics and the testing results of dynamic characteristics,its diesel engine was figured out through experiment,and than using Matlab/Simulink calculates the dynamics characteristic of the hydraulic mount system.Comparing the testing results,the simulation model is accurate.Through experiments,the engine mounting system's quantity,coordinates of center of mass,moments of inertia and mount stiffness are measured.With these parameters,the natural characteristics are worked out by program.Studying these data, it can be concluded that bigger vibration coupling still exist.All of these cause the vibration of system to turn worse.In order to improve the decoupling level and the degree of vibration,we properly adjust the system parameters by the energy theory.Finally,we take the evaluation of the vibration isolation,with an experimental study on the engine mounting system,vibration isolation performance between hydraulic and rubber mounting system was further analyzed,and we get a satisfaction result from the objective evaluation of the two mounting systems.