Abstract: Air is aspirated by cylinders of cylinder rows (11, 12) via branch pipes (23,24) from two intake collectors (21,22) of a V type multi-cylinder internal combustion engine. An auxiliary chamber (31, 32) is formed using the space between adjacent branch pipes (23,24). A communication port (25, 26) to the intake collector (21,22) of the auxiliary chamber (31,32) is formed between the openings (23A,24A) to the intake collector (21,22) of two adjacent branch pipes (23,24). Since the effective volume of the intake collector (21,22) increases due to the auxiliary chamber (31,32), residual resonance in the intake collector (21, 22) decreases. The auxiliary chamber (31,32) increases an intake inertia effect by increasing the flow rate of the branch pipes (23,24) in the second half of the intake stroke relative to the flow rate in the first half of the intake stroke. Engine volume efficiency is thereby improved using a limited space.

Abstract: An intake manifold (1) of a multi-cylinder internal combustion engine comprises a single pipe portion (4), a collector (5) connected to the pipe portion (4), and a plurality of branch pipes (6) branching from the collector (5) to each cylinder. The pipe portion (4) and the collector (5) divided into a plurality of spaces (1a, 1b) by a partitioning member (12). Blow-by gas is equally distributed to each cylinder using a simple structure comprising a discharge vent (3) for blow-by gas in the pipe portion (4) extending over the partitioning member (12) and being equal to the two spaces (1a, 1b). It is preferred that a notch (8) is formed facing the discharge vent (3) on the partitioning member (12).

Abstract: Air is aspirated by cylinders of cylinder rows (11, 12) via branch pipes (23,24) from two intake collectors (21,22) of a V type multi-cylinder internal combustion engine. An auxiliary chamber (31, 32) is formed using the space between adjacent branch pipes (23,24). A communication port (25, 26) to the intake collector (21,22) of the auxiliary chamber (31,32) is formed between the openings (23A,24A) to the intake collector (21,22) of two adjacent branch pipes (23,24). Since the effective volume of the intake collector (21,22) increases due to the auxiliary chamber (31,32), residual resonance in the intake collector (21, 22) decreases. The auxiliary chamber (31,32) increases an intake inertia effect by increasing the flow rate of the branch pipes (23,24) in the second half of the intake stroke relative to the flow rate in the first half of the intake stroke. Engine volume efficiency is thereby improved using a limited space.

Abstract: An intake manifold (1) of a multi-cylinder internal combustion engine comprises a single pipe portion (4), a collector (5) connected to the pipe portion (4), and a plurality of branch pipes (6) branching from the collector (5) to each cylinder. The pipe portion (4) and the collector (5) divided into a plurality of spaces (1a, 1b) by a partitioning member (12). Blow-by gas is equally distributed to each cylinder using a simple structure comprising a discharge vent (3) for blow-by gas in the pipe portion (4) extending over the partitioning member (12) and being equal to the two spaces (1a, 1b). It is preferred that a notch (8) is formed facing the discharge vent (3) on the partitioning member (12).