Muffler with reverse flow passages

A sound attenuating muffler for exhaust gas or the like comprising an elongated tubular housing of round cross section having an inlet at one end and an outlet at the other end and a frame inside the housing constructed and arranged to act with the housing to provide a retroverted path for gas to flow in flowing from the inlet to the outlet, said frame comprising a first transverse partition and a second transverse partition, said transverse partitions extending diametrically across and fitting inside of the housing, said first partition having a substantially imperforate wall with an opening for gas to flow through it, said second partition having a substantially imperforate wall with an opening for gas to flow through it, a first longitudinal partition secured to said first and second transverse partitions, said first partition being substantially trough-shaped with the base of the trough being located substantially adjacent and parallel to the longitudinal axis of the housing, said first longitudinal partition having one end aligned with the opening in the first transverse partition and the other end aligned with the wall of the second transverse partition, a second longitudinal partition secured to said first and second transverse partitions, said second longitudinal partition being substantially trough-shaped with the base of the trough being located substantially adjacent and parallel to the longitudinal axis of the housing, the trough shape of said first longitudinal partition defining a first longitudinal gas passage, the trough shape of said second longitudinal partition defining a second longitudinal gas passage, the space in said housing between said first and second transverse partitions and outside of said trough-shaped first and second longitudinal partitions defining a third longitudinal gas passage, one of said second and third longitudinal gas passages being connected at one end with the opening in said second transverse partition, and gas flow openings located between the first and second transverse partitions providing for transverse gas flow from the downstream end of one longitudinal gas passage to the upstream end of another longitudinal passage whereby said first, second, and third longitudinal gas passages provide said retroverted path for gas to follow in flowing from the inlet to the outlet.