Internal combustion engine exhaust manifold with cylindrical built-in catalyst container

Claim 1

An internal combustion engine exhaust manifold having a built-in catalyst container of a cylindrical shape, wherein said exhaust manifold comprises: upper and lower casings, a heat shielding liner of heat resistant material provided inwardly of and spaced from said upper and lower casings, and an air injection port provided within said exhaust manifold at a position adjacent a cylindrical catalyst container for injecting secondary air thereto during operation of an engine, said secondary air being fed from a secondary air pump which is separately mounted on said engine, said cylindrical catalyst container being filled with a catalyst suitable for cleaning the engine exhaust, and comprising concentric inner and outer cylinders having a radius differential of 20 to 30 mm., and annular lids fitting at opposite ends of said inner and outer cylinders to define therebetween an annular volume filled with said catalyst, said inner and outer cylinders having an upper wall portion with no perforations over a predetermined distance from the upper ends thereof and a lower wall portion containing multiple perforations which extend contiguously from said upper wall portion down to the lower ends of the cylinders such that the engine exhaust gas is introduced into said annular volume through perforations in said outer cylinder to undergo the cleaning reactions and then is discharged to the outlet of said exhaust manifold through the perforations in the inner cylinder of said cylindrical catalyst container, the cylindrical catalyst container being replaceably mounted through said heat shielding liner and having in the upper portion thereof a cover member to be fitted in said upper casing and a lower portion disposed in alignment with the outlet of said exhaust manifold.