Suction pipe system for multicylinder internal combustion engine

Claim 1

An intake system for a multicylinder internal combustion engine having first and second angularly disposed banks of cylinders with a certain firing order, comprising: (a) a monolithically formed intake manifold which extends longitudinally between said banks and has a longitudinal center plane, said manifold comprising a central, essentially straight tubular cavity extending the whole length of said manifold and having an inlet end and an outlet end on respective spaced ends of the cavity; first and second flanges extending in parallel to said tubular cavity and arranged on either side of said longitudinal center plane, and first and second individual suction pipes leading to the cylinders of the first and second cylinder bank, respectively, the first suction pipes extending from one end from the first flange adjacent to the second cylinder bank in a clockwise direction around said tubular cavity crossing said longitudinal center plane, and the second suction pipes extending from one end from the second flange adjacent to the first cylinder bank in an anticlockwise direction around said tubular cavity crossing said longitudinal center, wherein the first and second suction pipes are arranged side-by-side longitudinally of the intake manifold with a first pipe alternating with a second pipe, (b) a plenum chamber mounted by an intermediate flange on flanges formed on opposite ends of said first and second individual suction pipes extending in parallel to said tubular cavity and arranged on either side of said longitudinal center plane and having an internal cavity divided by a separation wall into two compartments, each compartment being in communication with an equal number of suction pipes of such cylinders of the first and second cylinder bank which follow each other in firing order and have a common ignition distance, (c) a part containing a throttle valve and connected to one end of said intake manifold and communicating the outlet end of said tubular cavity with the internal cavity of said plenum chamber, and (d) an air flow meter for a fuel injection system disposed in said central tubular cavity.