Study On Torsional Vibration Damping And Modeling Of Vehicle Powertrain Based On Unit Analysis

The vehicle powertrain which consists of engine, clutch, transmission and drivingwheels and so on, is a nonlinear coupling and complex system that contains bothcontinuous mass and concentrated mass, the resonance which intensifies torsionalvibration response of the system, will generate when the input excitation frequency isclose or equal to the inherent frequency of system, the introducing of dual massflywheel between the engine and transmission will be beneficial to solve the torsionalvibration phenomenon of the system.To explore the influence of kinetic parameters on dynamic response of the vehiclepowertrain, and realize the reasonable matching of the dual mass flywheel to achievethe purpose of reducing vibration, the current development status and trend of dual massflywheel and torsional vibration of the vehicle powertrain are systematically researched,detailed study and analysis on the units such as engine, dual mass flywheel, thetransmission and the drive wheels and so on of the vehicle system are carried out basedon the joint research with the enterprise, and the torsional vibration modeling of vehicledriveline based on unit analysis, the calculated results of systematic inherentcharacteristics show that the systematic inherent frequency range can effectively beadjusted by introducing dual mass flywheel to the vehicle powertrain, and the sensitivityof the kinetic parameters to the systematic inherent characteristics is analyzed in detail,and has revealed the internal relation between parameters and inherent characteristics ofsystem, that provides design foundation and theoretical guidance for new dual massflywheel torsional vibration damper and the reasonable matching and optimation ofsystematic kinetic parameters, the forced vibration simulation proceeded in ADAMSverifies that the torsional vibration response of the input excitation torque caneffectively be attenuated with the introduction of dual mass flywheel. The main researchwork includes the following several aspects：①The vehicle system is broken down into different subunits such as engine, dualmass flywheel torsional vibration damper, transmission, etc. based on its structure andfunction, and corresponding equivalent torsional vibration mechanical models ofsubunits are established, then the subunits are combined into torsional vibrationdamping analysis model of vehicle system through a certain criterion, thus the model ofvehicle powertrain based on unit analysis is obtained. For the subunit of engine, the dynamic model of single cylinder crank-link and its equivalent mechanical model arefirstly established, then the output characteristic of multi-cylinder engine can beobtained after phase combination, and be the input excitation to analyze the dynamicresponse of the system.②The corresponding free torsional vibration equation is established based on thetorsional vibration model of vehicle system, the calculated results of systematic inherentfrequency show that the first order resonance speed is below the engine idle speed, andthe second order resonance speed exceeds the highest engine speed, thus the resonancespeed of system can be isolated from the engine working speed, the influence of theparameters such as equivalent moment of inertia and the equivalent torsional rigidity onthe systematic inherent characteristics is discussed in detail, and has revealed theinternal relation between parameters and inherent characteristics of system.③The virtual prototype of the torsional vibration damping model of vehiclesystem is established in ADAMS, and the forced vibration simulation is proceeded, withintroducing the damping parameters and loading the excitation torque expression, theresults shows that the dual mass flywheel can preferably attenuate the torsionalvibration response of angular velocity produced by the input excitation torque.