INTAKE MANIFOLD FOR IN-LINE FOUR-CYLINDERED INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To miniaturize an intake manifold for an in-line four-cylindered internal combustion engine as well as ensure its uniform and sufficient charging efficiency to the cylinders. SOLUTION: An intake device for a four-cylindered internal combustion engine, which divides an straight-type four-cylindered internal combustion engine into two cylinder groups of which intake strokes do not occur in succession in the respective groups, comprises a first to a fourth independent intake passage 21, 22, 23 and 24, a first and a second resonance chamber 31 and 32 where the independent intake passages converge for the two cylinder groups, a first and a second resonance passage 41 and 42 extending upstream from the first and the second resonance chambers respectively, and a converging chamber 50 where the first and the second resonance passages converge. The arrangement and form of the first and the second resonance chambers, the downstream orientation of the first and the second resonance passages, and the arrangement of all the first to the fourth independent intake passages having proper curvatures which are not excessively small are made compact to ensure uniform and sufficient charging efficiency to the cylinders.