Research On Torsional Vibration Performance Of CVT Matched Flywheel Damper System

Compared with the traditional geared stepped transmission,the metal belt CVT performs well in terms of fuel economy,driving comfort and riding comfort,especially in the current environment of energy saving and emission reduction,it is more sought after by car manufacturers and drivers.When the metal belt CVT is used as the transmission device in the power transmission system,the torsional vibration of the entire transmission system is inevitably considered.As a kind of flywheel vibration reduction system,dual-mass flywheel is also the most effective torsional vibration reduction device.It is widely used in automobiles and has very good effects in changing the natural frequency of the power transmission system and eliminating noise.As people's requirements for fuel economy,driving comfort and riding comfort are further improved,vehicles equipped with DMF-CVT power transmission systems will become mainstream.At present,there is no systematic research on the matching and damping of DMF-CVT power transmission system.Therefore,based on the principle of DMF damping and the working principle of metal belt CVT,this paper studies the torsional vibration performance of DMF-CVT power transmission system.Firstly,according to the calculation method of the transmission system's rotational inertia and torsional stiffness,and based on the principle of bond graph modeling,a sub-model of the bond graph of the engine,dual mass flywheel,VT3 type metal belt CVT,reduction gear shaft,differential,drive wheel,automotive body,etc.were established,and each subsystem model was coupled to the vehicle model;according to the system causality and power flow direction to get the relationship between the state variables,and finally derive the vehicle dynamics model.Secondly,MATLAB/Simulink is used to perform dynamic simulation on the DMF-CVT power transmission system to obtain the angular acceleration fluctuation curve of the dual-mass flywheel primary and secondary flywheels under idling and driving conditions,and then the reduction of the dual-mass flywheel is analyzed.Vibration effect;The torsional stiffness of the dual-mass flywheel and the inertia ratio of the primary and secondary flywheels are optimized and analyzed,and the optimization results are obtained,and the optimization results are analyzed through simulation.Finally,taking a Dongfeng SUV as the test object,the vehicle road test was carried out under idling conditions and driving conditions to verify the correctness of the built simulation model and the actual vibration reduction effect of the dual-mass flywheel;The torsional stiffness of the mass flywheel is improved,and the road test of the improved dual-mass flywheel is carried out.The test results obtained are compared with the test results before the improvement to verify the correctness of the optimization direction.Provide reference value for the matching and optimization design of DMF-CVT power transmission system.