Combination catalytic converter and muffler for an exhaust system

A combination muffler and catalytic converter for an exhaust system, comprising a housing, inlet conduit means for introducing exhaust gas into said housing, outlet means for discharging gas from said housing, a catalytic conversion unit disposed within the housing between said inlet conduit means and outlet conduit means and being spaced therefrom, the portion of the housing located upstream of the catalytic conversion unit defining a mixing chamber, a venturi including a converging inlet section connected to and communicating with said inlet conduit means, an outlet section disposed within the mixing chamber and spaced from the catalytic unit and a throat section located between the inlet and outlet sections, at least a portion of the length of said outlet section diverging outwardly, air inlet means establishing communication between said throat section and the atmosphere, whereby air is drawn to said throat section by an aspirating action, flow restricting means adjacent the downstream end of said diverging section for restricting the flow of gas therefrom, said outlet section having a plurality of perforations disposed upstream of said flow restricting means and providing communication between the interior of the outlet section and the mixing chamber, the gases from said outlet section being discharged through said perforations into the mixing chamber, said flow restricting means enhancing the flow of gas through said perforations and into the mixing chamber to obtain improved blending of the air and exhaust gas in said chamber, the mixture of air and exhaust gas then passing through the catalytic conversion unit and being discharged through said outlet conduit means.