DESIGN OF AN ACTIVE NOISE CANCELLATION DEVICE FOR INTERNAL COMBUSTION ENGINES

摘要

An active muffler is developed and constructed to attenuate engine exhaust sound using active control. The muffler consist of an electrically driven valve, in series with a volume. Using the mean flow through the valve and the pressure fluctuations in the volume, the valve regulates the flow to the exhaust outlet in such a way that only the mean flow passes through the exhaust outlet. The fluctuations of the flow are temporally buffered in the volume. To carry out acoustical experiments on an experimental valve, a cold engine simulator is developed, which generates the exhaust sound with the matching gas flow using compressed air. The simulator allows quick and reliable acoustic and fluid dynamic experiments on exhaust prototypes. Comparative experiments and simulations show a good agreement between the behaviour of the engine simulator and a real combustion engine. In the near future, experiments will be carried out with the experimental valve on the cold engine simulator. The results will be evaluated on the basis of the expectations from the simulations.