Abstract

An exhaust muffler for a motor vehicle includes a louver tube having an intake end and an exhaust end. An outer tube, consisting of a frustoconical portion and a cylindrical portion, is concentrically arranged around the louver tube. A plurality of louvers and associated louver holes in the louver tube scoop a portion of gasses from the louver tube into the outer tube. An end cap, which includes an exhaust exit hole in its center, fits into an exhaust end of the outer tube. A plurality of end cap holes are arranged so that gasses leaving the outer tube flow through them. A restrictor disk between the end cap and louver tube includes a central hole coaxial with the louver tube and the exhaust exit hole of the end cap. Restrictor disk holes are in the restrictor disk between the central hole and its perimeter so that gasses leaving the louver tube flow through the central hole and the restrictor disk holes as they leave the muffler. A spiral vane defining a helical passage around the louver tube and inside the outer tube extends the path length of the gasses in the outer tube. A series of fins on the spiral vane extend orthogonal to an axis of the louver tube. A series of inner reverse cones are inside the louver tube upstream of its exhaust end. An exhaust system with this muffler is characterized by moderate backpressure at low rpms and little or negative backpressure at high rpms.