The Design Theory And Torsional Vibration Control Research Of Magnetorheological Fluid Dual Mass Flywheel

With development of economy and growth of living standard,vehicle has gradually become a necessity of daily life and work.NVH performance is becoming an important factor for passengers.There are plenty of factors effecting vehicle NVH performance and torsional vibration of drivetrain is one of the most effective.Because of the irregularity of engine torque,the drivetrain will generate torsional vibration and noise which influence the vehicle NVH performance.As an effective method to reduce vibration and noise of drivetrain,dual mass flywheel(DMF)is widely used.It not only could damp the engine torque fluctuation in idle and drive conditions,but also could reduce the torsional vibration resonance frequency to the speed below idle.However,this brings a negative effect.The use of DMF leads to the condition in which the drivetrain passes the resonance range when start or stop.This condition will cause big resonance amplitude which effects the vehicle vibration and noise.What's worse,it reduces the lifetime of parts.Although the resonance amplitude could be reduced through increasing damping,it would weak the torsional vibration damping performance in idle and drive conditions.This is to say the traditional DMF,whose damping performance can't be changed,could not satisfy the requirements of drivetrain in different conditions.The research of this paper relies on the Nation Science Foundation project(51205158).To satisfy different requirements in different conditions of drivetrain,magnetorheological fluid dual mass flywheel is designed and manufactured,based on the rheological behavior of magnetorheological fluid(MRF)which could be changed by magnetic field intensity.Damping characteristic of the device could be changed by magnetic field intensity which adjusted by current.Strong damping characteristic is offered to reduce the resonance amplitude in start,stop and other resonance conditions.Weak damping characteristic is offered to isolate engine torque fluctuate in idle and drive conditions.This paper contains six sections as follow.1.Combining the function and type of vehicle drivetrain,the torsional vibration problems and control methods of drivetrain is introduced.Then the function,structure,research status,production and application of DMF are introduced.Further,one of the most effective methods of drivetrain torsional vibration control is also introduced.And then the dominant sectors,rheological behavior,and applications of MRF are introduced to bring in the research object of the paper-magnetorheological fluid dual mass flywheel.2.The research necessity of MRF-DMF is exposed through the vibration isolation theory of vehicle drivetrain and the MRF-DMF is designed through stiffness,damping,magnetic circuit and total structure design.The magnetic FEM is analyzed to get the rule of magnetic flied intensity changing with coil current.Combining the rheological behavior of MRF,damping torque of device is analyzed by deriving the relationship of damping torque changing with structure parameters and coil current.Finally,the design is verified and the MRF-DMF is manufactured.3.According to the structure of magnetorheological fluid dual mass flywheel,the model is built in AMESim and torsional characteristic is analyzed.The static whole torsional characteristic and static partial torsional characteristic in different currents are analyzed and verified by static torsional bench.And then,based on the verified model,the high speed whole torsional characteristic and high speed partial torsional characteristic in different current are analyzed.4.The vehicle drivetrain model which contains engine,starter,magnetorheological fluid dual mass flywheel,transmission,shaft,final drive,differential,axle shaft,wheel and body is built in AMESim.And then the torsional vibration damping characteristic of drivetrain in different current is analyzed in start,stop,idle,constant speed,run-up and slow-down conditions.Finally,the ideal damping characteristic requirements of MRF-DMF in different conditions are gained through the contrast of torsional vibration damping result in different current.5.The torsional vibration damping characteristics in different control strategies are researched through co-simulation using AMESim and Simulink.The vehicle drivetrain model which contains magnetorheological fluid dual mass flywheel is built in AMESim while control system model is built in Simulink and then co-simulation is carried out through co-simulation interface.The torsional vibration damping characteristics of drivetrain are gained in start,stop,idle,constant speed,run-up and slow-down conditions respectively with ON/OFF,Fuzzy and Neural network control strategies.6.The controller of MRF-DMF is designed and manufactured based on the design of hardware circuit,schematic diagram and control system.The MRF-DMF and controller are installed on a light bus to verify the torsional vibration damping characteristics.The speed fluctuation of first mass and second mass of MRF-DMF is tested by using LMS and hall sensors.The torsional vibration damping characteristics of drivetrain with MRF-DMF and controller are gained in start,stop,idle,constant speed,run-up and slow-down conditions.Through the structure design and verification,modeling and test verification of MRF-DMF,modeling of drivetrain,research of control strategy and whole car test,the methods of MRF-DMF design and torsional vibration control are formed which will provide certain reference signification for later research.