Research And Application On Loaders Noise Control Strategy Based On CE Authentication

In recent years,the earthwork machinery has been widely used in many aspects of production process and engineering machinery because of its high strength,so it is in the process of production.Wheel loaders are mainly used for shoveling and short distance transportation of loose materials.They are widely used in railways,highways,wharves,mines,water conservancy projects and urban construction.It is one of the fastest growing parts of the earthwork machinery,and has the most demands in production and sales in the earthwork machinery.But earthwork machinery,including loaders,will cause great noise during walking and working.It will seriously pollute the environment,disturb people's normal life,study and work,and even endanger people's physical and mental health.Therefore,the noise problem of earthwork machinery has aroused general concern of the society.And noise reduction has become an important factor to improve product quality in the earthwork machinery industry.The low noise design and optimization of loader can enhance its competitive advantage in the market.In order to obtain the low noise wheel loaders and enhance market competitive of wheel loaders,this paper takes the wheeled engine produced by a domestic engineering machinery group as the research object;optimize components and structures of wheel loaders by use the method of test,theory analysis and finite element simulation.A low noise wheel loader is expected to meet the requirements of CE authentication to the noise instruction,thus providing a pass for the European and American market,and ultimately improving the international market competitiveness of the domestic loaders.Through the structural analysis of wheel loaders,this paper expounded the mechan ism and frequency of noise sources of loaders theoretically and designed orthogonal test to optimize the parameters of acoustic sponge.According to the test basis of the loader noise test and the requirements of CE authentication,the theoretical method system of the test,analysis,noise reduction methods and measures of the loader's whole machine noise control is put forward,which provides the theoretical basis for the noise control of loader.According to the sound absorption mechanism of the sponge,orthogonal design method is used.The three types of sound absorption sponges are regarded as the level,and the orthogonal test of external radiation noise is designed by sticking to the bottom of the cab,the top of the hood,the bottom plate of the frame and the side of the hood.The optimum selection of the sponge is as follows:the chassis floor and the cab paste 2#sponge,which is EPDM rubber plastic material sponge.The top side of the hood and hood paste 1#LE sponge sponge.The external radiation noise and the driver's position noise are tested.The noise of the driver's ear is 81.5dB(A)and the external radiation noise 110.3dB(A)of the whole machine is obtained.Compared with the sponge sound absorption measure,0.6 dB and 1.2 dB are reduced before the sound absorption measures are not used.The noise test test rig of the loader's working pump is designed,and the noise test of the loader's working pump is carried out.The noise signal is separated by the ICA algorithm,and the time domain signal of the gear pump noise and its decibels are obtained.The noise generated by pulsating flow and gear meshing can be reduced by increasing the number of gears and gear modification.In the test,the number of gear teeth was increased from 9 teeth to 12 teeth,and the tooth shape was fixed to drum shape,and the size deviation was controlled in 0.01-0.02mm.It was obtained that the rate of flow and pressure pulsation decreased by 5.7%under the rated working condition of the gear pump,and the tooth surface meshing force between gears was also reduced by about 30%.The noise ratio test was carried out on the test bench,and the gear pump was found in the test bench.The upper running noise power radiation noise is reduced from original 100.6dB(A)to 95.9dB(A),decreasing 4.7dB.By comparing the external radiation noise test of the machine after loading,the sound power level of the external radiation can be reduced from 110.3 dB(A)to 109.3dB(A)after the optimization of the sponge test.This measure can reduce the external radiation of the machine 1dB.The exhaust pressure of the original muffler is calculated by using the flow field analysis module AcuSolve in CAE software HyperWork.The actual exhaust back pressure is measured on the original machine,and the back pressure of the engine is 3.9kPa.The acoustic transmission loss of the muffler is analyzed.The transmission loss curve of the muffler is obtained by using the Virtual.Lab in the LMS software.By increasing the exhaust resistance to reduced noise,considering the existing structure and the limitation of the installation space,the number of perforated tubes in the exhaust muffler is reduced,and the 110.3dB(A)of the external radiation sound power level is reduced to 106.8dB(A)after the test of the sponge noise reduction measure,and the sound pressure level of the driver is reduced from 81.5 dB(A)to 77.7dB(A).The CE certification requirement of noise is less than 107 dB(A)outside the radiation power level,and 78 dB(A)for the driver's position sound pressure level.Through noise reduction measures,the noise level of loaders is improved to meet the directive requirements of EU CE certification,and has been certified by the third party certification bodies.