Abstract: A muffler construction having improved sound attenuation characteristics. A tapered tubular metal screen is disposed within the outlet conduit of a muffler and has a axis concentric with the axis of the conduit. The screen has a closed end preferably facing in a downstream direction with respect to gas flow, and the opposite open end of the screen is attached to the conduit. The screen acts to reduce the sound levels without increasing the overall size of the muffler and with a minimum increase of weight.

Abstract: A particulate trap exhaust muffler for use with a diesel engine and comprising a casing having an internal wall dividing the casing into an inlet chamber and an outlet chamber. The wall is formed with a plurality of openings and a plurality of generally parallel tubes are disposed within the outlet chamber with one end of each tube being mounted within one of the openings in the divider wall, while the other end of each tube is closed. At least a portion of the length of each tube is formed with perforations or holes. A cylindrical particulate trap is spaced concentrically outward of each tube to provide an annular chamber therebetween. Exhaust gas entering the inlet chamber flows into the tubes and through the perforations into the respective annular chambers to decrease the sound energy, and then passes outwardly through the cylindrical traps where particulate material is trapped and burned off. The exhaust gas then is discharged from the outlet chamber through an outlet.