Noise Analysis Of A Diesel Engine High Pressure Oil Pump Based On Transfer Path

As the important vibration source of the vehicle,the NVH level of the engine directly affects the NVH level of the vehicle,so it is necessary to control engine noise.In this paper,two different transfer paths are analyzed according to the actual engine noise problem of a certain automobile enterprise,and the transfer paths are optimized to reduce vibration and noise.This paper mainly reduces the transmission of vibration by optimizing the transmission path of high-pressure oil pump vibration,thereby reducing noise.The engine noise on the timing side is analyzed,and the high pressure oil pump is determined as the driving source.It is found that the stiffness of pump housing,the tensioning force of timing gear train and the stiffness of timing cover all have an effect on the transmission of vibration.Therefore,the tensioning force and timing cover of the pump housing and timing gear train are optimized to achieve the purpose of reducing vibration and noise.Design test and analysis of engine top noise are carried out,the wavelet analysis technology of noise is used to determine the high pressure oil pump as the noise source.Vibration of high pressure oil pump is transmitted through high pressure oil pipe,which forms engine top radiation noise.Through the test of transfer function and the modal test of high pressure oil pipe and high pressure oil pump,it is found that the high pressure oil pipe has the modal near the noise frequency.The actual excitation at the high pressure oil pump and high pressure oil pipe is collected,and the forced response of cylinder block,cylinder cover,high pressure oil pipe and high pressure oil rail is calculated.The noise cloud map on the top of the engine is consistent with the noise source location map.In order to increase the stiffness of the high-pressure oil pipe,make the resonance frequency of itself away from the excitation frequency,and increase the mass block to change the constraint state of the high-pressure oil pipe.Design optimization scheme optimizes the transmission path of high pressure oil pump vibration,and finally reduces the engine timing side and top noise by 12.3db(A)and 7.4dB(A),respectively.