Air rush silencer

Claim 1

A muffler for attenuating air rush noise in an exhaust gas system for an internal combustion engine, said system including an outlet, comprising a housing having a reduced size inlet for attachment to said outlet, a straight through gas flow tube supported in the housing to receive all gas from said inlet, said tube and housing defining an annular passage surrounding the tube, said tube and said annular passage having transversely separated outlets inside said housing with the annular passage outlet surrounding the tube outlet and both outlets spaced axially upstream from the downstream end of the housing, said tube having a reduced cross section portion therein providing a restriction to gas flow through the tube, said tube having a perforated wall upstream of the restriction and the restriction forcing some gas to flow through the perforations in said wall into the annular passage whereby the gas flows in two separate parallel streams in said housing, said housing having an open downstream end extending across substantially the full and largest cross section of the housing and a curved wall portion axially aligned with and spaced downstream from the outlet of the tube whereby gas in said separate streams impinges upon said curved wall portion prior to passing out of said open downstream end.