I.c. engine EGR system with by-passable EGR cooler to reduce condensation

摘要

An EGR system for a turbocharged compression-ignition i.c. engine comprises a two-pass full flow EGR cooler 142 and a bypass valve 151 downstream of the EGR valve 134 and upstream of the EGR cooler 142 to reduce EGR condensation. The two-pass EGR cooler 142 maintains a higher EGR mass flow velocity resulting from a smaller cross-sectional area so that EGR flows more easily and fouling is reduced.