Patent ID: 7506723

Claim:
A muffler for an exhaust gas system of an internal combustion engine comprising: a housing having at least one exhaust inlet and at least one exhaust outlet; a control device; a silencer system; a first and a second pipe on said exhaust inlet or outlet ends, said first pipe being switchable at least between an open state and a closed state by said control device, and being acoustically coupled to said silencer system such that said silencer system is active when said first pipe is opened as well as when said first pipe is closed, said silencer system having a different damping characteristic when said first pipe is opened than when it is closed, wherein at least one of said first and second pipes is permanently open, and wherein said housing is partitioned into a first, second and a third chamber, said third chamber being between said first and second chambers, and said at least one permanently open pipe passes through said third chamber and is acoustically coupled to said third chamber.