Study On Noise Control Of A Commercial Vehicle Cab Considering Intake Pipe Optimization

As the front end device of the intake system of commercial vehicle,the main engine provides clean and sufficient air for the engine,which ensures the power of the engine.In recent years,with the development of NVH technology and the application of various new materials,the overall NVH performance of the automobile has been greatly improved.Especially in the noise control of engine body,it is found that the noise of all kinds of automobile engine body in the market is effectively controlled,but the noise of the intake is second large noise sources,whose frequency components are complex and change,can easily contribute to the noise of cab if they are not effectively improved.In this paper,the big roar phenomenon in the cab of a commercial vehicle under the exhaust brake condition is controlled and improved.According to the actual car test,the analysis data is found from the pipe,the roar frequency is in the 80-315 Hz,and the first 8 orders of the air duct are found with the imitation true analysis.There is a coincidence phenomenon between the frequency and the frequency of the roar,because the structural design of the air duct is unreasonable,which causes the roar of the cab in the exhaust brake.Finally,the noise of the cab is eliminated by designing a parallel resonant cavity in the air duct,and the noise of the driving cab is reduced by 5dB as a whole.The research contents of this article are as follows:(1)The main sources and frequency components of the roar are found by using LMS equipment to find out the main sources and frequency components of the roar.The main components of the problem are found through the first test data.(2)Using the CAE analysis method,the geometric model of the trachea is first established by CATIA software.Secondly,the modal parameters of the air duct are calculated by using the Hyper Mesh software,and the structural performance of the pipe is analyzed.(3)In order to verify the reliability of the simulation model established above,the modal test of the Impact Testing module in LMS is used to carry out the modal test on the real car tube,and the structural response is obtained by the way of the moving force hammer knocking the structural vibration of the tube,so as to calculate the test modal parameters of the pipe,and through the simulation and the test reference.The comparison of numbers to verify the established simulation model of the intake pipe has research value.(4)The design muffler includes the 1/4 wavelength tube and the cavity to eliminate the roar,among which the effect of the 1/4 wavelength tube is not obvious.Therefore,a parallel resonant cavity is designed at the upper end of the tube to eliminate the roar frequency,and the experiment proves that the method is feasible and the improvement is achieved.