Research On Modification Of Transmission Shaft For Passenger Car Based On NVH And Transmission Performance Lifting

In this paper,a kind of cross-boundary vehicle was used as the research object,and the efficiency of the transmission shaft and the VNH were promoted.The Birfield joint drive scheme was proposed.The performances of the two transmission shafts were analyzed by theoretical research and virtual prototype simulation.The performance improvement requirements of the improved design of the drive shaft were determined and verified by the relevant experiments.The specific analysis processes were as follows:(1)Firstly,the output characteristics of the Kinematics and Dynamics of a single Hook universal joint were obtained based on the Cross-shaft Kinematics and Dynamics Theory;the formation and the regular pattern of the additional bending moment were analyzed without considering the friction moments.Next,the output of the double Hook universal joints system with 0°and 90°phase were analyzed and the most concise equal velocity output conditions were revealed.The Kinematics responds of the double Hook universal joints system with any phase were obtained.Finally,the output characteristics of the Kinematics and Dynamics of the Birfield joint were analyzed.Compared with the Hook universal joints,the Kinematics and Dynamics output of the Birfield joint are equal with input,and the additional bending moments are steady without fluctuation.(2)The kinematic differential equations of the cross shaft universal joint were established by using the Centralized quality method and the equivalent of the mass and the moment of inertia of the drive shaft of the typical triad arrangement.The non-damped state output responses were solved.The differential equations of the Birfield joint drive shaft were established to solve the output response in the non-damped state.In contrast to the two drive shafts,the Birfield joint drive shaft can weaken the torsional vibration of the shaft tube;the smooth operations of the transmission trains were facilitated.(3)The equivalent concentration of the additional bending moments on the intermediate support of the three – Hook universal joint were analyzed,and the mathematical description of the exciting force of the intermediate support horizontal X and the vertical direction Y at any angle were obtained.The mathematical formulations of the excitation force in direction X and direction Y were obtained under the arbitrary rotation angles of the Birfield joint transmission shaft,and the actual vehicle installation parameters and the drive shaft parameters were used to calculated the excitation forceunder the actual working conditions.Compared with the two kinds of transmission shafts,the additional bending moments of the Birfield joint transmission shaft stabilize the intermediate support excitation,which are helpful to reduce the vibration that the transmission shaft transfer to car body.(4)In the ADAMS virtual prototype,the dynamic response of the two kinds of transmission shafts under actual operating conditions,the vertical acceleration of the intermediate support and the transmission efficiency of the drive shaft were simulated with the actual vehicle installation parameters.The simulation results showed that the acceleration,dynamic fluctuation and transfer efficiency of the intermediate support vibration of the Hook universal joint transmission shaft were greatly affected by the driving bridge beating,while the Birfield joint transmission shaft had good adaptability.The intermediate support accelerations were small and stable,the fluctuation amplitudes of the dynamics fluctuated slowly and the transmission efficiency were stable.(5)The two kinds of transmission shafts were respectively carried out on the bench efficiency experiment,vehicle fuel consumption experiment and vehicle road experiment.The bench experiment results showed that the Birfield joint transmission shaft had higher transfer efficiency at low and medium speeds,and the results were confirmed in the vehicle fuel consumption experiment.The vehicle fuel consumption experiments showed that the use of Birfield universal transmission shaft had lower vehicle integrated fuel consumption,which achieved the goal of vehicle fuel consumption;vehicle road experiments showed that the Birfield joint transmission shaft could reduce the vehicle middle row and back row passengers' ear noises effectively,while the main reducer meshing noise also had a certain improvement and achieved vehicle NVH upgrade target.