Patent ID: 7293627
Filing Date: 2007-11-13
Classification: F01N

Abstract:
1. An active exhaust muffler for an exhaust system of an internal combustion engine, said muffler comprising: a pipe system, adapted to be permeable for airborne sound in a first space; a housing through which said pipe system passes; a partition having a wall opening, said partition separating a second space from a third space; an antisound generator situated in said second space and acting upon said third space with antisound through said wall opening during operation; a sound outlet to transmit airborne sound, said first space in communication with said third space through said sound outlet; and a labyrinth provided in said third space blocking a direct path between said sound outlet and said wall opening for the propagation of airborne sound and supplying at least one indirect bypass for the propagation of airborne sound between said sound outlet and said wall opening.