Sound-attenuating muffler for exhaust gases

Claim 1

A sound-attenuating muffler for reducing the acoustic energy in an exhaust gas stream, comprising: an elongated muffler housing having a tubular outer wall and an axis, at least three vanes axially extending between a first position adjacent to one end of the housing and a second position adjacent to the other end of the housing, said vanes extending radially between the axis and said wall to define an odd number of axially extending flow passages, at least one axially extending sound-attenuating section defined by three partition plates axially spaced in the downstream direction, said partition plates including an entry partition blocking all said passages but one entry flow passage, a reverse flow partition blocking all said passages but an exit flow channel, and an exit partition blocking all said passages but said exit flow channel, said vanes defining transfer port means including one flow port in at least two of the vanes, the respective positions of the flow ports in the respective vanes alternating from a position adjacent to the flow-reversing partition to a position adjacent to the entry partition to provide a serpentine exhaust gas flow path traversing the sound-attenuating section in alternating directions along each flow passage in sequence from the entry flow channel to the exit flow passage, and a resonator chamber in each said section, positioned between the flow-reversing partition and the exit partition and extending across said flow passages except the exit channel, said resonator chamber being interconnected by open ports defined in each of said vanes not bounding the exit channel, and the resonator chamber communicating with said serpentine flow path via at least one opening into the entry channel.