Abstract
Keywords - New concept exhaust system design, volume reduction, weigth-cost improvement, acoustics quality, standard fullfillment.
Abstract - At present, and due to the social pressure against urban noise, the legal Regulations stablished concerning the matter, have the tendency to limit the noise emited by the vehicles, in circumstances where the effectivity of the exhaust systems is essentially valuated.
So much is it, that other noise sources, initially secondary, like the engines noise or the roll noise of the tyres, have become more important in the global noise emited by the vehicles.
In this study it is presented a new concept of the exhaust system, where the acoustic objective is not to ANNUL the noise of the exhaust system, but to filter this noise in order to reach a balance of acoustic energy in the different engine orders, with predominance of the low frequencies and the absence of metallic and of gas flow noises, in a way that, the resulting SOUND will show at the same time the QUALITY, STRENGTH and SPORTINESS of the engine, fulfilling, logically, the Legal Regulations of Exterior Noise.
Additionally to the improvement of the ACOUSTIC IMAGE of the vehicle, these new exhaust systems require a lower volume and weight in comparison with the traditional designs.