Intake manifold structure

Abstract

Provided is an intake manifold structure for an internal combustion engine including an intake manifold defining a plurality of branch passages () communicating with corresponding intake ports () of the internal combustion engine () arranged in a cylinder row direction thereof, and provided with additional gas introduction ports () communicating with the respective branch passages, and an additional gas introduction passage forming member () attached to the intake manifold, and defining an additional gas inlet () and additional gas introduction passages () communicating the additional gas inlet with the corresponding additional gas introduction ports, wherein the additional gas introduction passage forming member extends across the branch passages, and is provided with a guide wall () for defining the additional gas introduction passages in cooperation with an outer surface of the intake manifold and an inner surface of the additional gas introduction passage forming member.