Patent ID: 7661415

Claim:
An EGR cooler comprising: a core having a flat first flow passage and a second flow passage alternately arranged side by side; a casing fitted to an outer periphery of the core; header portions for an exhaust gas arranged at both ends of the casing in a longitudinal direction coincident with flow or the exhaust gas; a bypass duct formed between an inner surface of a bypass duct portion of the casing and a side of the core, said bypass duct portion of said casing being bent to have a cross section in an arc; said bypass duct portion of said casing having a heat stress absorbing portion including ribs configured as at least one of inner ribs or outer ribs, the ribs being arranged side by side in the longitudinal direction and extending in a circumferential direction of the arc while being separated from each other in the longitudinal direction; the first flow passage of the core accepting cooling water and the header portions directing the exhaust gas to and from the second flow passage; and a switch configured for switching and guiding the exhaust gas to either of the core or the bypass duct.