The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental ...The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental verification are studied.First,considering the stick-slip phenomenon in the clutch engagement process,a detailed 9-degrees-of-freedom(DOF)model including the body,each cylinder of the engine,clutch and friction lining,torsional damper,transmission and other driveline parts is established,and the calculation formula of friction torque in the clutch engagement process is determined.Second,the influence of the friction gradient characteristics on the amplification or attenuation of the automobile friction judder is analyzed,and the corresponding stability analysis and the numerical simulation of different friction gradient values are carried out with MATLAB/Simulink software.Finally,judder bench test equipment and a corresponding damping test program are developed,and the relationship between the friction coefficient gradient characteristics and the system damping is analyzed.After a large number of tests,the evaluation basis of the test is determined.The research results show that the friction lining with negative gradient characteristics of the friction coefficient will have a judder signal.When the friction gradient value is less than-0.005 s/m,the judder signal of the measured clutch cannot be completely attenuated,and the judder phenomenon occurs.When the friction gradient is greater than-0.005 s/m,the judder signal can be significantly suppressed and the system connection tends to be stable.展开更多
High temperatures are generated due to the sliding contacts between the rubbing surfaces of the friction clutch system.In this work,by considering the effective thermal contact conductance under sliding conditions,a s...High temperatures are generated due to the sliding contacts between the rubbing surfaces of the friction clutch system.In this work,by considering the effective thermal contact conductance under sliding conditions,a simulation model of a two-dimensional transient temperature field of the clutch disc was developed.A numerical solution to obtain the surface temperature at different radii was presented based on the finite difference method.Compared with the experimental data,the proposed model for estimating the surface temperature is more accurate than the conventional prediction method.The results showed that the errors of the calculated temperatures at radii of 114 and 106 mm have obviously reduced by 12.98%and 12.60%,respectively.In addition,the influences of pressure and relative speed on the surface temperature were investigated.The temperature increases with the increase of the relative speed and pressure during the sliding period,and there is an interaction effect between pressure and speed on the surface temperature rise.展开更多
基金Supported by National Natural Science Foundation of China (Grant No.51775249)。
文摘The friction judder characteristics during clutch engagement have a significant influence on the NVH of a driveline.In this research,the judder characteristics of automobile clutch friction materials and experimental verification are studied.First,considering the stick-slip phenomenon in the clutch engagement process,a detailed 9-degrees-of-freedom(DOF)model including the body,each cylinder of the engine,clutch and friction lining,torsional damper,transmission and other driveline parts is established,and the calculation formula of friction torque in the clutch engagement process is determined.Second,the influence of the friction gradient characteristics on the amplification or attenuation of the automobile friction judder is analyzed,and the corresponding stability analysis and the numerical simulation of different friction gradient values are carried out with MATLAB/Simulink software.Finally,judder bench test equipment and a corresponding damping test program are developed,and the relationship between the friction coefficient gradient characteristics and the system damping is analyzed.After a large number of tests,the evaluation basis of the test is determined.The research results show that the friction lining with negative gradient characteristics of the friction coefficient will have a judder signal.When the friction gradient value is less than-0.005 s/m,the judder signal of the measured clutch cannot be completely attenuated,and the judder phenomenon occurs.When the friction gradient is greater than-0.005 s/m,the judder signal can be significantly suppressed and the system connection tends to be stable.
基金This work was supported by the National Natural Science Foundation of China(Grant No.52105232)the Fundamental Research Funds for the Central Universities(Grant No.2022YQJD02).
文摘High temperatures are generated due to the sliding contacts between the rubbing surfaces of the friction clutch system.In this work,by considering the effective thermal contact conductance under sliding conditions,a simulation model of a two-dimensional transient temperature field of the clutch disc was developed.A numerical solution to obtain the surface temperature at different radii was presented based on the finite difference method.Compared with the experimental data,the proposed model for estimating the surface temperature is more accurate than the conventional prediction method.The results showed that the errors of the calculated temperatures at radii of 114 and 106 mm have obviously reduced by 12.98%and 12.60%,respectively.In addition,the influences of pressure and relative speed on the surface temperature were investigated.The temperature increases with the increase of the relative speed and pressure during the sliding period,and there is an interaction effect between pressure and speed on the surface temperature rise.
