The active noise control (ANC) method employing secondary acoustic sources is effective at low frequencies and is suitable for lowering the exhaust backpressure, thus offering the possibility of increasing the engine power output and fuel consumption efficiency of the vehicle. To apply the ANC method to the exhaust noise control of a vehicle, the secondary sound sources must be protected from the heat of exhaust gas and a satisfactory level of ANC trackability and stability must be achieved during accelerated running. In this study, a practial ANC system (active muffler) for the exhaust noise was developed. According to the analytical data obtained from a medium-duty diesel truck during accelerated running, this active muffler was designed to protect its speakers from thermal influence and was aimed specifically at reducing the harmonic components of exhaust noise at low frequencies. To avoid the thermal influence of exhaust gas, the exhaust pipe portion that comes in contact with the active muffler was given a double-pipe structure for heat insulation. In addition the active muffler was shaped so as to receive the maximum cooling effect from the ambient air during driving. To verify the heat insulation effects, chassis dynamometer tests were conducted using a test vehicle equipment with the active muffler. The time base synchronized filtered-X algorithm (SFX-TB method) simplifies the calculation of reference signals by assuming the input of a pulse train synchronous with the fundamental frequency of input signals and has faster convergence performance. The experimental active muffler was mounted on a medium duty diesel truck to examine the trackability and stability performance of the ANC system on the condition of accelerated running. The effectiveness of the proposed scheme for attenuating the thermal influence on the active muffler was verified by the vehicle test.
An active muffler for medium-duty diesel vehicles considering acceleration characteristics
ANC (active noise control) in einem Nutzfahrzeug bei Beschleunigung
JSAE Review ; 21 , 4 ; 576-578
2000
3 Seiten, 5 Bilder, 5 Quellen
Aufsatz (Zeitschrift)
Englisch
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