.4100 Match The Acoustic Characteristics Of The Qb Engine Exhaust Muffler System Analysis And Experimental Research

It is the main measure that by means of exhaust system to control the noise of automobile. Also it is an important issue to design the muffler which has good performances and little effect on power of engine in automobile's noise controlling field. The variability of muffler's volume and dimensional structure parameters of exhaust pipe in exhaust system has some effect on the noise controlling performance. If the two aspects can be matched reasonably, doing research on muffler performance by means of system improvement, the optimum plans or methods will be obtained, having important significances on noise controlling, and muffler designing. Therefore these two aspects are taken as the main research content and object in this paper.Based on many kinds of technology parameters of 4100QB engine, the main research has been done. By means of designing and theoretical knowledge of muffler, the theoretical structure parameters of muffler were determined according to designing flow, then the three dimensional modules for a series of mufflers of different volumes and many kinds of exhaust pipes of different dimensional parameters which matching with each other to form a number of exhaust systems were established. And numerical analysis and calculation of three dimensional FEM have been done for each module by means of SYSNOISE, obtaining the distribution graphs of transmission loss and sound pressure level at each frequency, comparing out the muffler performance, and finally the comparison and verifying of analysis results and noise spectrum which obtained by accelerating noise testing have been done.The results indicate that muffler effect of the A muffler whose diameter of cross section is 150mm is stronger in low frequency range while muffler effect of the D muffler whose diameter of cross section is 220mm is stronger in frequency range after 2500Hz, and muffler effect of the E muffler whose diameter of cross section is 260mm is the weakest, not being adopted. The smaller the pipe diameter of exhaust pipe, the more transmission loss can be achieved, muffler effect being better, and the comparison of muffler effect is more remarkable when pipe diameters have great differences.The muffler effect of bend pipe is better than that of straight pipe in low and middle frequency range and in part of high frequency range while muffler effect of straight pipe is better in high frequency range after 2100Hz. From the testing results, analysis and calculation, the conclusion can be drawn that the exhaust system matched with C muffler whose diameter of cross section is 180mm has better muffler effect in low and middle frequency range and part of high frequency range, and its peak of sound pressure level is the lowest, muffler frequency spectrum being much wider. Generally speaking, the system of that C muffler whose diameter of cross section is 180mm matched with 1 bend pipe whose pipe diameter is 42mm is the best exhaust muffler system.From analysis results and testing, the conclusion can be drawn that if the stronger muffler effect can be achieved in low and middle frequency range, the exhaust pipe of bend pipe should be adopted. On the contrary, if the stronger muffler effect can be achieved in high frequency range and under the conditions of automobile chassis space allowing, the exhaust pipe of straight pipe can be applied for matching, and that its pipe diameter is smaller than that of muffler inlet is better. Big volume muffler should not be adopted, and it is better to match with exhaust pipe to achieve the aim of controlling noise.