New semi-active muffler system based on the H-Q tube concept

Abstract

For a fixed bandwidth noise, the appropriate control device is used to change the internal structure of the semi-active muffler to get the large amount of noise reduction. This paper analyzes the principle of Hershcel-Quincke tube, then according to the principle of the Hershcel-Quincke tube, a semi-active silencing device is presented here, which can effectively control the noise. Then a test bench basing on the design is built. The control system which includes the control of the valves and the stepping motor is studied here. In the conditions without flow, the acoustic characteristic testing has been done using the control systems. It shows that the valves and the stepping motor have a rapid response, meanwhile, the testing results are identical with the theoretical control state, which achieves the control of the semi-active muffler. According to the analysis of the testing results, the muffler has a good noise reduction effect to low frequency noise and the harmonic frequency noise corresponding to the low frequency. It shows an average noise reduction of 10dB as well as the maximum noise reduction approaching to 35dB, which reveals the excellent noise reduction characteristic of the muffler.