Research And Improvement On The Noise Attenuation Characteristics Of Internal Combustion Forklift Intake System

The intake system is main noise source of internal combustion forklift,thus,it is significant to research the intake system and reduce the noisy of it.Main parts of intake system include intake system,intake muffler and air inlet piping,the noise eliminating performance of the whole intake system is the total reflection of all these parts.This paper research the noise eliminating performance of some forklift intake system and provide some improvements to reduce the noise of intake system,The main work include the followings.First,analyze the generation mechanism and evaluation index of system noise,and extend the evaluation index based on insertion loss and sound pressure level,the new index is more suitable to the noise experiment of intake system.Second,analyze the noise eliminating performance of dissipative muffler,expanded muffler,Helmholtz resonant muffler and perforated panel structure,elaborate the design and calculation methods of noise eliminating performance about these structures,and study the influence to transmission loss of noise eliminating structures.Find reasonable method to establish a good acoustic finite element model of air cleaner and perforated panel structure though acoustic finite element theory.Third,test the noise of forklift intake system.Provide 15 combination projects to improve the noise eliminating performance of intake system based on the test data gotten,analyze the 15 different projects by acoustic finite element simulation software Virtual Lab,and estimate the efforts of improvements.Finally,test the noise on the 15 different improved projects,find out the one with best noise attenuation performance of these improvements,and the best solution reached,and the expected target;vehicle noise also has a well reduction effect.