Research On Torsional Vibration Of The Powetrrain And The Influence To The Vibration Of The Mini-bus

In recent years, the auto industry of China has developed rapidly. China's auto productionand sales has been ranked first in the world from2009to2011for three consecutive years.Mini-bus has got the good development opportunities and played an important role inChina's car market by the positive national policy, the growth rate of urbanization processand so on. With the lighter structural of the vehicle and continuous increase of the velocity ofthe vehicle, the torsional vibration of the powertrain of the vehicle becomes more and morecrucial. It will affect the power performance, fuel economy, ride comfort, driving safety ofthe vehicle adversely. It is necessary to research torsional vibration characteristics of thepowertrain.Engine is not only the main excitation of the torsional vibration of the powertrain, but also isan important factor of the vibration of the vehicle. During the actual driving, the driveroperates the throttle pedal and the clutch pedal according to the traffic environment. Itchanges the engine torque and causes the torsional vibration of the powertrain and thevibration of the whole vehicle.The former researches of the torsional vibration of the powertrain were focused on the steadyconditions of the vehicle.This paper is based on the project "the study of the transientvibration of the vehicle", which is the cooperation between the study team and ChongQingChangAn Automobile Company Limited. The mini-bus virtual prototype model wasestablished by the multi-body dynamics software ADAMS/Driveline. The engine speedlinear increase condition, constant torque condition, constant throttle condition, impulsetorque condtion, starting process condtion, speeding up condtion, acceleration anddeceleration transition condtion were simulated. And relative analysis of the simulations wasput forward. The main contents of this paper are as follows:(1) Construction of the mini-bus virtual prototyping modelBased on the original data given by the enterprise, the modeling parameters, modelingcoordinate system, the modeling unit system and the modeling process was elaborated in thefirst place. The mini-bus virtual prototyping model was established by ADAMS/Drivelineincluding the powertrain subsystem, macpherson suspension subsystem, double wishbonesuspension subsystem, steering subsystem, braking subsystem and body subsystem. Theconstruction procedure of the powertrain subsystem, which including engine, clutch, gearbox,transmission shaft, final drive, differential, drive shaft, tire and so on, were described indetail. The construction procedure of other subsystems of the virtual prototype was described in general.(2) Simulation and validation of the mini-bus virtual prototyping model in typical conditionsBased on the mini-bus virtual prototyping model, the speed scanning simulation wasexecuted by ADAMS/Driveline and obtained the simulation value of the correspondingtransmission output shaft speed, driving wheel speed in certain engine speed. By comparingthe simulation value of the transmission output shaft speed, the driving wheel speed and theirrespective theoretical calculation, the rationality of the mini-bus virtual prototyping modelwas validated preliminary from simulation and theory angle.Based on the original data given by the enterprise, the mini-bus model was established byCarSim software. By setting the same simulation conditions in CarSim and ADAMS, threekinds of simulations were executed. The engine torque was constant in one simulation. Theengine torque changed based on the engine speed characteristic curve in the other simulation.The engine torque was the shack pulse form in another simulation. By comparing the twosoftware simulation curves of the torque and the revolving speed of the powertrain,automobile vehicle velocity and longitudinal acceleration in the same simulation, therationality of the mini-bus virtual prototyping model was further validated from two differentsoftware contrast angle.(3) Simulation of the mini-bus virtual prototyping model in unsteady conditionsBased on the mini-bus virtual prototyping model, the simulations of the normal starting andthe fast starting condition, the speeding up condition, the acceleration and decelerationtransition condition were realized by the standard simulation of ADAMS/Driveline. Thestarting simulation and the speeding up simulation were validated by CarSim. Theacceleration and deceleration transition simulation was realized by the bench test simulationof ADAMS/Driveline. For every kind of the unsteady condition simulation, the acutenessdegree of the torsional vibration of the powertrain and the influence degree of thelongitudinal vibration and the vertical vibration of the vehicle were analyzed. From theanalysis of the simulation, there are some conclusions. The influence degree of thelongitudinal vibration of the vehicle caused by the torsional vibration of the powertrain isrelatively large and the influence degree of the vertical vibration of the vehicle caused by thetorsional vibration of the powertrain is relatively little.Based on the project which is mentioned above, this paper constructed the mini-bus virtualprototyping model including the complete powertrain subsystem, which is advantageous tothe dynamic tracking of the pressure and the motion state of the powertrain system and isconvenient for the study of the torsional vibration of the powertrain. The rationality of the mini-bus virtual prototyping model was validated through two methods. The one issimulation and theory comparison validation, the other one is different software simulationcomparison validation. The validation methods that mentioned above can provide referenceto the validation of other models. The starting condition, the speeding up condition, theacceleration and the deceleration transition condition were realized by ADAMS/Driveline.The qualitative analysis of the torsional vibration of powertrain and the longitudinalvibration, the vertical vibration of the vehicle of these three kinds of unsteady conditionsimulations can be a foundation to the further study of reducing the vibration and improvingthe ride comfort and executing other simulations.