Research On Analysis And Control Of Tractor Driver's Ear-side Noise

NVH(Noise,Vibration,Harshness)is a key indicator of vehicle performance.Tractors are the most commonly used agricultural machinery,which NVH performance has been increasing attention.At present,when the tractor is working,the sound pressure level of driver's ear-side noise is high,and how to effectively decrease the tractor noise based on the control of costs is the main task.However,there is not any complete set of control systems for decreasing the noise level of the tractor driver's ear-side noise.Therefore,in this paper,a type of tractor as the object of study,to reduce the main noise source as the basic principle,in reducing the tractor driver's ear noise on the basis of the aim of establishing a set of general tractors for the complete driver's ear Noise control scheme.In this paper,aiming at the problem that the driver' s ear-side noise is higher than the standard,the research is carried out with the cab as the object of research based on the independent component analysis and the finite element simulation.Using the independent component analysis algorithm studies the contribution of the driver's ear-side noise,and the finite element method is used to study the contribution of panel sound pressure to driver's ear-side noise in the simulation of panel acoustic contribution analysis.Firstly,in view of the application of independent component analysis on the limit of the test channel and the requirement of the test location,the appropriate application method of independent component analysis for tractor is given.In the ICA study on cab noise,considering that the number of air noise sources of direct wheeled tractors is relatively small and the transmission system is relatively simple,the study object is attributed to one structural noise source,and the muffler,air filter,engine,Fan four air noise sources.In the study,it is assumed that the driver's ear-side noise signal is linearly superimposed by the above five noise sources,and the feasibility of this hypothesis is discussed through the simulation signal,which greatly reduces the limitation of the test channel and test position.So the problem of underdetermine mixture blind source is transformed into positive definite blind source.Based on this,the mixing matrix is obtained by using the independent component analysis algorithm,and the energy calculation factor is introduced to obtain the contribution of these five noise sources to the driver's ear-side noise.Secondly,considering the problem that structure noise dominates driver' s ear-side noise,finite element simulation is studied to improve the control of noise.It is found that the edge and the bottom plate,which are the main structural parts of the tractor and the vibration characteristics are obvious,can decrease the vibration of the plate by modal matching and frequency response,and,however,cannot significantly reduce the ear-side noise level of the tractor driver.Therefore,using the panel acoustic contribution analysis directly changes the normal sound pressure of the panel to the driver's ear-side,and change the cab's existing reverberation state,from the root to decrease the driver's ear-side noise.The study shows that the panel acoustic contribution analysis based on sound pressure,and the corresponding rectification,can effectively reduce the structure noise of the tractor cab,and thus can effectively reduce the driver ear noise.In this paper,through independent component analysis and other relevant analysis,the quantitative analysis that accurately calculates the proportion of structure noise in tractor cab noise from the qualitative analysis that structure noise dominates tractors cab noise is realized.Through modal matching,frequency response and panel acoustic contribution method to analyze the structure noise in the cab,the qualitative analysis that the structure noise that coursed by the air noise to the panel resulting in panel vibration,rather than the vibration that caused by engine,dominates the whole structure noise in cab noise is realized.Based on the above theory,the driver's ear-side noise control scheme suitable for general tractor is put forward,which is applied to a kind of tractor prototype,which reduces the driver's ear-side noise.