Research On Excavator Cab Structure-borne Noise With Operational Transfer Path Analysis

The NVH performance of a excavator has a direct impact on the driver's physical and mental health,and it's the core competitiveness of excavator products.More and more engineers and technicians have pay their attention to improve the excavators' NVH performance.Cab noise is one of the important indexes of the excavators' NVH performance,and to reduce the noise as much as possible is the key to improve the NVH performance.Therefore,the study on the noise in the cab of the excavator has certain theoretical significance and engineering application value to explore the principle of noise generation and put forward effective improvement measures.Based on the method of operational transfer path analysis(OTPA),relying on the engineering practise program of "the noise control research on XX type excavator",this paper studies the structure-borne noise in the cab of a certain type of hydraulic excavator,and put forward the improvement measures.Firstly,based on the OTPA method,the calculation method of the transfer function and the path noise contribution is derived.And two improved measures are put forward to overcome the shortcomings of this method:(1)By comparing the spectrum of synthetic signials to that of measured signals,determine whether the important paths are missing;(2)By applying the S VD technique to process test data,improve the accuracy of the OTPA model.Secondly,through the analysis of cab noise sources and its mode of transmission,an OTPA model,which takes engine vibration as system input and cab noise of driver's right ear as system output,is established in this paper.And then the experiment is designed to build and verify the OTPA model.The test data that under the speed of 1140r/min,1254r/min,1430r/min,1650r/min,1765r/min and 1870r/min is used to calculate the system transfer function and path contribution;and the test data that under the speed of 950r/min,1545r/min and 2100r/min is used to verify the OTPA model.By comparing the spectrum of synthetic signials to that of measured signals,the OTPA model is proved to be effective and can be used for subsequent analysis.Finally,by applying the improved OTPA method to process the test data,and by analysing the transfer function and path noise contribution of the OTPA model under the analysis speed,the important transfer paths,which need to be improved,and thesensitive frequency position are identified.The analysis results show that the the performance of the left rear position absorber and the structural resonance frequency should be improved.Aiming at the structural resonance problem,and based on the modal analysis method,the rectification and optimization of the excavator frame structure is carried out,and the improvement effect is verified.The research shows that it is feasible to apply the OTPA method to the transfer characteristics analysis between the engine vibration and the cab structure noise of the hydraulic excavator.The OTPA method not only can effectively identify the noise source,but also can locate the path which has a greater impact on the targetnoise,and provides a reliable theoretical guidance to solve the cab noise problem.