An intake duct for an internal combustion engine includes a pipe-shaped shell. The shell includes a first molded product and a second molded product. The first molded product is formed by a plastic molded product and includes an opening extending through the first molded product in the thickness direction. The second molded product is formed by a fiber molded product produced through compression molding. The second molded product includes an air-permeable fitting projection fitted into the opening, and the second molded product is joined with an outer surface of the first molded product.

An intake duct for an internal combustion engine includes a pipe-shaped shell. The shell includes a first molded product and a second molded product. The first molded product is formed by a plastic molded product and includes an opening extending through the first molded product in the thickness direction. The second molded product is formed by a fiber molded product produced through compression molding. The second molded product includes an air-permeable fitting projection fitted into the opening, and the second molded product is joined with an outer surface of the first molded product.

This multi-cylinder engine intake structure is provided with a fresh air distribution chamber into which a plurality of fresh air distribution openings communicating with the individual intake ports are opened, and a gas collection chamber. The gas collection chamber includes a communication region into which a first communication opening communicating with the fresh air distribution chamber is opened, a first mixture region into which an air inlet and an EGR gas inlet are opened and which is positioned upstream of the communication region in a flow direction of a mixture gas of air and EGR gas, and a second mixture region positioned downstream of the communication region in the flow direction of the mixture gas.

This multi-cylinder engine intake structure is provided with a fresh air distribution chamber into which a plurality of fresh air distribution openings communicating with the individual intake ports are opened, and a gas collection chamber. The gas collection chamber includes a communication region into which a first communication opening communicating with the fresh air distribution chamber is opened, a first mixture region into which an air inlet and an EGR gas inlet are opened and which is positioned upstream of the communication region in a flow direction of a mixture gas of air and EGR gas, and a second mixture region positioned downstream of the communication region in the flow direction of the mixture gas.

A charge air line of an internal combustion engine for supplying multiple cylinders of a cylinder bank of the internal combustion engine arranged in-line with charge air, has multiple charge air line sections. Emanating from each charge air line section a branch leads to a cylinder, the branch screwable to a cylinder head of the respective cylinder. The charge air line has an upstream end, via which charge air is feedable to the charge air line, and a downstream end, which is closed by an end cap. At the downstream end, the charge air line has a larger flow cross section than at the downstream end.

A charge air line of an internal combustion engine for supplying multiple cylinders of a cylinder bank of the internal combustion engine arranged in-line with charge air, has multiple charge air line sections. Emanating from each charge air line section a branch leads to a cylinder, the branch screwable to a cylinder head of the respective cylinder. The charge air line has an upstream end, via which charge air is feedable to the charge air line, and a downstream end, which is closed by an end cap. At the downstream end, the charge air line has a larger flow cross section than at the downstream end.

An engine system may include: an engine including cylinders that generate a driving torque by combusting fuel; a first intake manifold connected to an intake line through which flows intake air into some of the plurality of cylinders; a second intake manifold supplying the intake air to the other cylinders of the plurality of cylinders through the first intake manifold; a first exhaust manifold connected to some cylinders that are connected to the first intake manifold; a second exhaust manifold connected to some other cylinders that are connected to the second intake manifold; a recirculation line branched from the second exhaust manifold to be coupled to the second intake manifold; a recirculation inlet valve disposed at a point at which the recirculation line and the second exhaust manifold are joined; and a manifold connection valve disposed on an intake line between the first intake manifold and the second intake manifold.

An engine system may include: an engine including cylinders that generate a driving torque by combusting fuel; a first intake manifold connected to an intake line through which flows intake air into some of the plurality of cylinders; a second intake manifold supplying the intake air to the other cylinders of the plurality of cylinders through the first intake manifold; a first exhaust manifold connected to some cylinders that are connected to the first intake manifold; a second exhaust manifold connected to some other cylinders that are connected to the second intake manifold; a recirculation line branched from the second exhaust manifold to be coupled to the second intake manifold; a recirculation inlet valve disposed at a point at which the recirculation line and the second exhaust manifold are joined; and a manifold connection valve disposed on an intake line between the first intake manifold and the second intake manifold.

The engine includes a cylinder head provided over a cylinder row, an intercooler provided on one end side of the cylinder head in a row direction of the cylinder row, an air supply manifold to introduce air from the intercooler to the cylinder head, and a cooling piping connected to the intercooler, where the cylinder head, air supply manifold, and cooling piping are arranged in a width direction intersecting the row direction of the cylinder row in stated order of the cylinder head, air supply manifold, and cooling piping, and in a cross section of the air supply manifold taken along a line intersecting the row direction, a length along the width direction is shorter than a length along a direction intersecting both the row direction and the width direction.

The engine includes a cylinder head provided over a cylinder row, an intercooler provided on one end side of the cylinder head in a row direction of the cylinder row, an air supply manifold to introduce air from the intercooler to the cylinder head, and a cooling piping connected to the intercooler, where the cylinder head, air supply manifold, and cooling piping are arranged in a width direction intersecting the row direction of the cylinder row in stated order of the cylinder head, air supply manifold, and cooling piping, and in a cross section of the air supply manifold taken along a line intersecting the row direction, a length along the width direction is shorter than a length along a direction intersecting both the row direction and the width direction.