Analysis And Optimization Of Rattle Noise In Dual-Clutch Transmission

As people gradually raise for car comfort requirements,NVH(Noise,Vibration and Harshness)problem of the car has attracted more and more attention.Among them,the transmission rattle has obvious broadband and noise level jump phenomenon,which can easily be ear recognition,has become the main noise source of automobile transmission system in the low speed region,need reasonable solutions.In this paper,an automotive transmission system was selected,which is equipped with a wet dual clutch transmission,as the research object,using bench testing and simulation to analyze the rattle of the transmission.In this paper,the rattle threshold of the non-loaded gear is predicted and the influence factors of the rattle noise are analyzed by the simulation model.The main work and contributions of this paper are as follows:(a)The simulation model of wet dual clutch transmission is established by using AMESim software.The model includes input motor,dual mass flywheel,clutch,gearbox(gear pair,synchronizer,shaft and bearing etc.),the main reducer,differential,axle,wheel,PID control system and shift control system.In this paper,the method of establishing the dynamic model of the shafting system is studied,and this method is used to simplify the automobile transmission system.In this paper,the modeling method of the main parts are described in detail,at the same time,the rationality of the main part and the calculation ability of the whole model are verified.(b)Then,the dual clutch transmission rattle tests have been done on experimental bench.The experimental data show that the non-working shaft gear pair cannot contribute to the overall noise of the gearbox,and the AMESim simulation model is accurate.While being analyzed,the excitation frequency has great effect on gear rattle,and with the increase of the excitation frequency,rattle strength decreased;the influence of the oil temperature on the gear rattle is the second,and with the increase of the lubricating oil temperature,the rattle noise increases;the average torque has little influence on the gear rattle.The analysis shows that can optimize gear rattle by increasing the excitation frequency,improving the cooling effect of the lubricating oil and reducing the lubricating oil temperature.(c)Experiments and simulation results are used to predict the rattle thresholds of the gear pair that may have rattle noise.In this paper,two different prediction methods are used in the experiment and simulation,respectively.The results of the two methods are compared,and the advantages and disadvantages of the two methods are compared.(d)Using the AMESim simulation model,the main parameters of the transmission system were analyzed by sensitivity analysis,and the rattle evaluation index was used to determine the rattle degree of the parameters.Through analysis,the dynamic torque fluctuation and the drag torque are the most influential to the gear rattle.The inertia of the first flywheel and the loose gear has a great influence on the gear rattle.The inertia of the second flywheel,the flywheel stiffness and the backlash have a moderate effect on the gear rattle,and the inertia of the vehicle,the inertia of the axle,the meshing stiffness of the working gear and the non-working gear have little effect on gear rattle.At the same time,according to the analysis results,an effective method to optimize the transmission rattle noise problem is put forward.