Internal combustion engine having two-stage exhaust-driven supercharger and charge air cooling between low pressure and high pressure compressors

1. An internal combustion engine with a two-stage exhaust gas turbocharger having a low pressure stage and a high pressure stage, the combustion engine comprising:

a connection duct disposed between a compressor of the low pressure stage and a compressor of the high pressure stage;

a charge air intercooler comprising a section of the connection duct and a cooling insert positioned in the section of the connection duct, wherein a coolant flows through the cooling insert;

wherein a wall of the section of the connection duct forms a housing part of the charge air intercooler and defines a flow rate volume that is sufficient for effectively cooling charge air while flowing in the section of the connection duct around the cooling insert;

wherein the section of the connection duct is formed as a substantially straight intercooler area that is open at at least one first axial end and has laterally deviating elbows on respective end regions or each axial end for supplying or conducting away the charge air, and

wherein the cooling insert is configured as a pre-assembled cartridge comprising a base plate and a plurality of cooling pipes provided exteriorly with a plurality of cooling ribs, wherein the cooling pipes fit into bores formed in the base plate and communicate with a coolant distribution channel configured in the base plate.

2. The internal combustion engine of claim 1 , wherein each cooling pipe of said cartridge is provided with a cylindrical band at one end, wherein each of said cooling pipes is installed by pressing, welding, or soldering with said band into a blind-hole bore in said base plate in a position perpendicular to said base plate, and wherein each cooling pipe, at another end, is provided with a sealing sleeve on a cylindrical band, wherein each cooling pipe communicates with a respective inner bore with the coolant distribution channel in the base plate.

3. The internal combustion engine of claim 1 , wherein the cartridge is insertable into an interior of the section of the connection duct through the at least one first axial end that is open and with the sealing sleeves on the cooling pipes, protrudes into holding bores provide at a second, opposite axial end of the section of the connection duct, wherein the cartridge, with its base plate, can be detachably flanged onto the at least one first axial end in a leakage-free manner, and wherein the second, opposite axial end of the section of the connection duct is closed by a cover fastened to said second, opposite axial end, wherein said second, opposite axial end is adjacent to the sealing sleeves, and wherein said cover is provided internally with a coolant distribution duct that is supplied externally with a coolant and communicates with a first portion of the cooling pipes, wherein said cover further includes a return duct connected with an external coolant return pipe that communicates with a second portion of the cooling pipes.

4. The internal combustion engine of claim 3 , wherein the cooling insert formed as a cartridge includes three cooling pipes arranged parallel to one another in one plane and having the same length and structure, wherein coolant flows through two of said three cooling pipes parallel in a first direction and wherein in one of said three cooling pipes, coolant flows in a second, opposite direction and forms a quasi-cooling-insert-internal return pipe for the coolant.

5. The internal combustion engine of claim 3 , wherein the wall of the section of the connection duct surrounds the cooling insert at a distance that is smaller than a diameter of the cooling pipes.