Research On Design Method Of Tuned Frequency Band-gap

Using intake muffler was one of the most effective methods to control the intakenoise. Intake mufflers designed for model machine usually can not reach the expectedsilencing effect due to differences of engines’ noise spectrums and manufacturing andassembling deviations of intake system when used for volume production. In this paper,the design method of tuned frequency band-gap was researched, applied to an excavatorfor controlling intake noise and used for optimizing the intake system.Firstly, the intake system was tested and simulated. Noise spectrums were tested andanalyzed. Transmission loss of the intake muffler was tested using three-point method.Transmission loss and flow field characteristics were simulated based on finite elementmethod. The results showed that the largest contribution of intake noise was the noisesource near200Hz.The generation mechanism and controlling methods of intake noise were summarystudied. The design requirements, evaluation criterion and common elements wereintroduced. Especially, soundproofing theory and modifier formula of resonator werediscussed in detail. Models with different draw ratio were established and simulated forverification.The design process of tuned frequency band-gap was divided into four parts,determining the design goal, structure design, simulation analysis and experimentalverification, and respectively summary researched. Especially, frequency modulationand its performance analysis were close studied. The design method of tuned frequencyband-gap was used to improve intake system of the excavator. The simulation resultsshowed that the design meets the design objective. The regulation of200Hz±10Hzrange was realized. The transmission loss of original intake system was improved bynearly45dB,when resonance frequency is tuned to200Hz.