Exhaust muffler including venturi tube

Claim 1

A muffler for an internal combustion engine comprising: a housing defining an inlet end and an outlet end; an inlet tube passing through the inlet end of the housing; a venturi section disposed within said housing and axially spaced from said inlet tube, defining a passage for gases substantially smaller in cross-section than said housing and aligned generally axially with respect to said outlet end, comprising: a reducing bell forming the inlet of said venturi section communicating with said inlet tube for reducing the effective cross-sectional area of said passage to at most about half its original size; a straight section of tube of invariant cross-section coupled to the outlet end of said reducing bell; a gradual diffusing tube connected to the outlet end of said straight section and increasing the effective diameter of said passage to substantially the original inlet diameter of said reducing bell; a perforate section of tube axially connecting said diffusing tube with the outlet defined by said housing, wherein substantially all said gases pass through said venturi section; and a plurality of imperforate baffles interposed between said housing and said inlet tube, said venturi section, and said perforate tube, dividing the interior of said muffler into a plurality of sealed chambers, the end of said inlet tube in said muffler and the inlet of said venturi section both being disposed in the same one of said chambers.