Air precleaner for internal combustion engine

Claim 1

In an air precleaner for installation upstream of the air filter on the air intake side of an internal combustion engine, in which the precleaner includes an upright outer cylindrical casing with a top air intake opening, an inner clean air discharge tube centered within said casing and extending into said casing a substantial distance with a clean air discharge opening at the upper end thereof to define an air chamber between the sidewalls of the casing and tube and being spaced below said top intake opening, air spinning means positioned within said casing between said top air intake opening and said clean air discharge opening for imparting a downward centrifugal spinning motion to air entering said casing, whereby dirt-laden air follows a downwardly spiraling path between the sidewalls of the casing and the tube, the improvement comprising an inverted generally frusto-conical bottom wall closure for said casing in surrounding relationship to said discharge tube and a substantial distance below said clean air discharge opening, said bottom wall defining one only generally radially extending slot opening therethrough with the upstream edge of the slot offset below the downstream edge of said slot and said slot discharging to atmosphere, whereby clean air is discharged from said casing centrally through said discharge tube and dirt-laden air is discharged from said casing to atmosphere through said slot, said air chamber within said casing between said bottom wall and said air spinning means being unobstructed so that said downward centrifugal spinning motion within said chamber continues unimpeded to said bottom wall.