Field Balancing Of Vehicle Transmission Shaft Based On The Influence Coefficient Method

The transmission shaft is one of the most important rotating components and have serious effect on the NVH(Noise,Vibration and Harshness)performance of the vehicle.All sub-components of the transmission assembly have been balanced with special dynamic balancing machines before assemble,but due to the unavoidable assemble error and its multi-stage structure,poor working conditions,etc.,it is easy to generate new unbalance failures under whole vehicle condition,which in turn affects vehicle NVH performance.This research work focuses on balancing the transmission shaft with original unbalance under the condition of whole vehicle.Based on the influence coefficient method,the performance of different vibration signal processing methods to extract unbalance information are explored.Finally,the order analysis method based on zero-crossing oversampling is developed.The dynamic balance of transmission shaft under the whole vehicle state was performed,and the first-order vibration amplitude of the response position of the balanced target vehicle was significantly reduced,which effectively improved the NVH performance of the vehicle.Firstly,the cause and classification of umbalance,and the relating basic conceptions are summarized.The theory of the influence coefficient method is introduced and simulated in detail.Then,it is deduced to the generalized situation of multi-response planes,and the process of real application is summarized.Secondly,to quantify the effect of speed fluctuations on the extraction of unbalanced information,the amplitude normalized unbalance signal is used to simulate signals with different speed fluctuations.Then,the target frequency amplitude and phase error from the fast Fourier transform(FFT)are clearly identified.Subsequently,the applicability of unbalance signal processing based on zero-sampling oversampling,Empirical Mode Decomposition(EMD),and Variational Mode Decomposition(VMD)methods are explored.Simulation and verification experiment results show that,the EMD based method shows poor accuracy and noise stability,and the VMD method shows good noise stability and high accuracy,but it faces difficult parameter selection and low computational efficiency.The zero-oversampling based method has the best overall performance and is suitable for field unbalance signal processing of four-wheel drive vehicle transmission shafts.Finally,based on the theory of influence coefficient,the developed signal processing method was used to perform field balancing of the transmission shaft of the target vehicle.The transmission shaft is simplified as a four-response planes four-correction planes of rotor support model.The balance results show that the vibration amplitude of each measurment plane decrease by 41.6%,6.2%,28.5%,and 53.6%.This method effectively improves the NVH performance of the target vehicle.