Research On The Matching Between Length Of Transmission's Shaft Pipe And NVH Performance Of Crossover

The transmission shaft assembly is an important part of transmission system of vehicle,and its vibration performance directly has an influence on the NVH performance of vehicle during running.One automobile works has been working on improving the quality of its one crossover,and based on the research achievements,the efforts has still been devoted to do related research to improve the quality of crossover,with the hope to realize the energy saving and emission reduction.This paper summarized related research on vibration analysis of transmission shaft and based on the research achievements on the research crossover.This paper has mainly done research on the matching of length of shaft pipe and NVH performance.To get the best NVH performance between length matching and NVH performance of transmission shaft,providing a means to improve the quality of vehicle.So it is significant to do research on the this subject.This paper took one transmission shaft assembly as research goal,and has done some research as below.Combing the corresponding parameters of research crossover,and based on Euler-Bernoulli theory,deducted the critical rotational speed calculation formula of single transmission shaft.Then valuated some data to get the result,and compared it with finite method and empirical formula,verified the accuracy of the beam theory used in this paper.Last,took account of the fuzzy reliability design of vibration,and confirmed the length range of single transmission shaft,which satisfied the vibration reliability,namely,L<1084mm.To describe mathematical relationship between length matching of shaft pipe and vibration response qualitatively,this paper took lumped mass method and combined the Lagrange equation,basic dynamic principles to build 7 degrees of lateral-torsional coupling vibration of transmission shaft,then simplified it and converted it to differential equation related to length of main transmission shaft pipe.As the motivation caused by the engine and rear axle can not be definitely described by math formula.Besides,the external excitation of intermediate support includes several component forces,and it changes dynamically,so it is hard to solve the differential equations directly.Given that the ADAMS software has advantages to solve the multiple body dynamics,and its solving theory is also based on Lagrange equation,mechanics principle and mathematics theory.So the virtual prototype technology has been used to solve the problem,and the rigid-flexible coupling vibration model of different length matching of transmission shaft assembly were built combining the finite technology.Then supplied constraints and drive to the prototype to simulate the acceleration condition of fifth gear to get its vibration response.Used Origin to plot the simulation results and analyzed the curve to finally get the conclusion that when the length of middle transmission shaft pipe and main transmission shaft pipe is 658 mm and 729 mm,the NVH performance is best.Besides,this paper also did research on the installation mode of transmission shaft and the stiffness of intermediate support and got that when the transmission shaft is installed by firstly parallel connection and then series connection,and the stiffness of intermediate support is between 450-550N/mm,the acceleration measured from it was relatively small and fluctuated gentle.Finally,the modal experiment and noise experiment were done on condition that the vehicle was driven at the acceleration of fifth gear.The correctness of simulation analysis was proved.