Simulation And Experimental Study On Starting Vibration Of Friction Clutch Automobile

Judder and shuffle is the two kinds of common vibration during the engine start process.Seriously affect the driving experience of the driver and passengers.Judder phenomenon is common in the clutch engagement process,mainly for the longitudinal vibration of the vehicle body,low frequency.Shuffle is commonly seen when the engagement has just been completed,the same vibration pattern as judder,but the frequency is lower and the amplitude is higher.The two kinds of starting process vibration are both closely related to the friction clutch:The negative gradient of clutch friction coefficient will lead to self-excited vibration,the misalignment of driving and driven part of clutch will cause the axial force fluctuation,leading to forced vibration,when these two vibrations transmit to the wheels and body through the driveline,judder appears.The impact of the clutch or the sudden change in the load of the driveline after the completion of cluth engagement will cause the low frequency resonance of the driveline,resulting in shuffle phenomenon.The multi-stage torsional damper located on the clutch driven plate assembly has the important effect of attenuating the torsional vibration of the vehicle drive system.The wave plate which also located on the driven disc assembly can play a role in buffering the clutch engagement.Therefore,a good match of clutch and driveline is critical to restrain the starting vibration.At present,domestic manufacturers due to the lack of understanding of the parameters clutch jitter,so there is a certain blindness in the clutch and transmission system matching,not only spend a lot of time and energy and are often difficult to achieve the desired effect.Therefore,the study of friction clutch on judder and shuffle,for the prevention and improvement of vehicle starting vibration is of great significance.In this paper,based on a new model which in the clutch matching stage,the following modeling and simulation studies and real vehicle tests are carried out:(1)Modeling and analysis of the starting vibration,the results show that the excitation form of the judder is divided into the self-excited vibration caused by the negative gradient of the friction coefficient and the forced vibration caused by the misalignment leaded axial force fluctuation.The vibration frequency of the former is the natural frequency of the driveline,the vibration frequency of the latter is the fluctuation frequency of the axial force and the amplitude of vibration increases with the amplitude of the axial force fluctuation.Shuffle is low frequency reasonance of driveline caused by the engagement of the clutch,the change of the load or the change of the throttle opening and its essence is also a kind of forced vibration.(2)The six-degree-of-freedom dynamic model of the automobile driveline is established by using the centralized quality modeling method.The engagement process of the clutch is simulated and analyzed.In the process of modeling,the three nonlinear characteristics of the clutch are considered:multi-stage torsional nonlinearity,axial nonlinearity and friction nonlinearity.(3)The dynamic response calculation and frequency domain analysis are carried out by substituting the driveline parameters into the established six-degree-of-freedom model.The accuracy of the modeling is verified by comparing the simulation of the shaft speed curve and the longitudinal acceleration curve of the gearbox.The frequency analysis results show that the frequency of judder is the first order nonzero natural frequency before completion of clutch engagement,and the frequency of shuffle is the first order nonzero natural frequency after the completion of clutch engagement.The nonlinear characteristic parameters of clutch driven disc are analyzed under the single variable simulation,and the effects of the parameters on the starting vibration are obtained.(4)The experimental study of the starting vibration of the vehicle is carried out,and the test method and evaluation standard of judder and shuffle are put forward.According to the influence of the parameters of the clutch driven plate on the starting vibration,the parameters of the clutch driven plate are adjusted.After adjustments the simulation and real car test are carried out again,results show that judder and shuffle are improved,which proves the correctness of analysis of influence parameters of the driven disc,it also verified that the theories,simulation and test methods have certain practical significance in the engineering.