Patent ID: 7681629

Claim:
An exhaust gas heat exchanger for a liquid cooled internal combustion engine, in which heat exchange between exhaust gas and liquid coolant is performed, the exhaust gas heat exchanger comprising: a heat exchange core having a plurality of flat tubes laminated in a thickness direction, each flat tube defining an exhaust gas passage in which the exhaust gas flows; and a plurality of coolant flow pass holes formed in each of the flat tubes, each of the coolant flow pass holes penetrating the flat tube in the thickness direction, wherein the plurality of the flat tubes are laminated in the thickness direction in such a manner that no space is left between adjacent flat tubes, wherein the coolant flow pass holes of each flat tube are connected with the coolant flow pass holes of the other flat tubes, in order to respectively form a plurality of coolant flow passages through which liquid coolant flows, wherein the coolant flow pass holes of each of the coolant flow passages communicate with each other in the thickness direction, so that the coolant flow passages are formed to be perpendicular to the exhaust gas passages, and wherein the exhaust gas heat exchanger further comprises: a first tank plate laminated on a top end of the heat exchange core in a laminated direction of the flat tubes to form an inlet side tank portion in communication with one end of a first group of the coolant flow passages so as to distribute the liquid coolant into the first group of the coolant flow passages, and to form an outlet side tank portion in communication with one end of a second group of the coolant flow passages so as to collect the liquid coolant from the second group of the coolant flow passages, and, a second tank plate laminated on a bottom end of the heat exchange core in the laminated direction to form a distributing tank portion in communication with other ends of the first and second groups of the coolant flow passages so as to collect the liquid coolant from the first group of the coolant flow passages and to distribute the collected coolant into the second group of the coolant flow passages.