Analysis And Optimization Of Cab Noise For Large Tractor

Generally,the tractors work on the poor road and have long working time,the noise becomes serious at this point,especially for a large horsepower tractor.As the driving speed becomes faster,and the requirements on the ride comfort and healthy of the driver becomes higher,how to effectively reduce the parotic noise is a hot research topic in the field of agricultural machinery.The parotic noise is not only associated with the performance of the dampers,but also related to the acoustic characteristics of the cab.Therefore,the parotic noise can be an index to evaluate the performance of the damper,and a useful guidance on how to decorate the cab using acoustic materials.Taking DongFeng 1204 large tractor as the prototype,firstly,we theoretical analyzed the source of the parotic noise and its mechanism,to get the components of the parotic noise which were air noise ? reverberation sound and solid noise.Then,using the method of the elimination,covering and surface acceleration testing to verify.On the one hand,to properly identify the level of noise,and the contribution of parotic noise,so that we can verify the theoretical analysis of parotic noise;On the other hand,with the help of parotic noise spectrum analysis results,the parotic noise was divided into two parts,the medium-high frequencies and low frequencies.The noise with medium-high frequencies comes from air noise and reverberation sound,which can be reduced by using the optimized combination that combines several acoustic packaging materials in sequence.The experimental results showed that the parotic noise was reduced by a 12.1 dB sound pressure level by the optimized combination.The noise with low frequencies comes from the imbalance of the inertia force of the engine during the second order reciprocating motion,which is hard to be reduced by optimizing the packaging materials.Both the stiffness and damping of the damper should be optimized to reduce the multi-axis vibration,this way cut off the transmission of the noise to the cab.At this time,Firstly,RecurDyn,the multibody dynamics analysis software was used to create model of the damper and cab.Experimental test data was used to verify the accuracy of the model.After that,the Meta optimization method was used to optimize the stiffness and damping.After optimization,the experimental results showed that the rate of isolation of the cab was improved effectively,which means the noise with low frequencies was reduced,and the ride comfort was improved.Finally,the paper summarized the methods that reduce the parotic noise of a large horsepower tractor,especially,the optimization of the combination and the optimization of the damper,which reduce the parotic noise with the medium-high frequencies and low frequencies,respectively.The final results showed these methods achieved expected affects in the noise reduction so that the prototype met the industrial standard about the parotic noise.