Noise Source Identification And Evaluation Technology For Forklift And Its' Application

Forklift truck,as a main mechanical tool in china's modernization construction,has played an important role.However,noise has become one of the most important indicators to evaluate the performance of mechanized equipment as relevant national and international standards are becoming more and more strict.Meanwhile,with the improvement of people's living quality and quality pursuit,much concern has gradu-ally been paid to the acoustic comfort of complete machine.The control method for noise will change from the meeting of limited value to the optimization of acoustic comfort.Therefore,in order to reduce the noise radiation level and improve the acoustic comfort,relevant research on noise reduction and evaluation technique of sound quality were carried out in this paper.Firstly,based on the analysis of noise characteristics for engineering vehicles,the advantages of the sound source scanning positioning system Scan&Paint in the noise source identification of engineering vehicles and its working principle were pointed out.Taking a certain internal combustion counterbalance forklift truck as prototype,noise source tests were respectively done in its idle and rated speed.The result that the main noise source of the forklift truck are engine body and tail pipe was obtained combining the acoustic theory knowledge.Besides,their sound power spectrum con-centrate mainly on the low frequency stage.According to the results of noise source identification test,relevant measures concerning noise control were proposed.Secondly,in order to evaluate the acoustic comfort of the forklift truck,40 noise signals was collected and processed.Taking annoyance as the subjective evaluation indicator,rating score comparison method as the evaluation indicator and its system as the subjective evaluation software,pre-evaluation and comprehensive evaluation were done which provides us with all the annoyance level of samples.At the same jective parameters and analyzing their correlation with annoyance.The result shows that the main objective parameter that influences annoyance is loudness..Finally,according to theoretical research and experimental results,improvement solutions like the reduction of engine speed,sound absorption and isolation were proposed to reduce the exterior radiation noise for the forklift truck.A test was carried out according to the industrial standard and requirement.The results show that the radiation noise of the improved prototype decreased to some extent.Objective calcu-lation was done for the improved noise signal.The result shows that compared with the original subjective evaluation value,the improved prediction value of annoyance decreased.Namely,the expected goals including the reduction of noise and the im-provement of acoustic comfort were achieved.