Sources Analysis And Features Recognition Of Noice In The Cab Of Wheel Loader

Energy and the environment are two important issues of this century, Noise is animportant aspect of environmental pollution.When the development of constructionmachinery moves toward complexcity,large-scale and high speed,its noise and vibrationproblems become more and more prominent and have direct adverse impact on the qualityof life and human health. This thesis on the ground of college-enterprise cooperatedproject Research on the key technology of noise control of wheel loader.the thesisconcentrate on analysis noise source in cab of wheel loader and its feature recognition.Asthe noise source diagnosis and study on the contribution rate is the premise of noisecontrol, it is of great theoretical value and important engineering applications to Researchon the wheel loader indoor noise source and character recognition,and it points out thedirection for Reduce the noise of wheel loader.This paper tested the loader cab noise,the noise of the engine and the vibration ofrelated components through test method.To explore the method that combine componentanalysis,wavelet transform and empirical mode decomposition,and identificate the mainsource of loder cab noise and transmission path by this method.using the Partial coherenceanalysis method examined the coherence between the cab noise and cab structurevibration,and proposed measures to reduce the noise in cabin.the results of research isdescribed as follows:1. the noise sound pressure level of Tested wheel loader driver position is87.4dB(A).the number Meet the national standard of "people’s Republic of China national standardof earthmoving machinery noise limit" the first stage limits (89dB (A)), But can not meetthe second stage limits that will be implemented in2015,(86dB (A)).the junction of eachside in the cab and many through holes for the control mechanism on the floor is the mainpath to transmit noise.2. through The analog signal mixing and unmixing process, verified the independentcomponent analysis and empirical mode decomposition fusion technology for mixed signalseparation ability, Proved the feasibility of combination of ICA and EEMD method forinentify the loader cab noise source characteristics.3. introduced the principal of EEMD-ICA and its application in blind source separation of a loader under different conditions,and obtained a series of independentcomponent. Using Fourier transform and wavelet transform technology to each componentfeatures analysis to identify the independent component and corresponding relation ofinternal combustion engine noise.combining time-frequency analysis results and priorknowledge,identify the main noise source of the cab include exhaust noise,cooling fannoise and combustion noise and the contribution of noise was obtained.4. Using partial coherence analysis method to analyze the correlation of indoor noiseand cab structure vibration. the main noise source control measure were put forward such asprevent noise transfer from outdoor to indoor, improve the sound insulation performance ofcab structure, recommend measures to lower the floor vibrationa, etc.Based on the EEMD+ICA modal,effective identification of noise sourcecharacteristics in wheel loader cab could be achieved in relatively simple test condition.atthe same time,this modal was put forward as foundation and technical method support forengineering machinery noise control.