Abstract: A tube 101 is constituted by a pair of plates 111a, 111b which are fitted with each other in such a manner as to put an inner fin 101b between the plate 111a and the plate 111b. Differences in level 111c are formed on the second plate 111b, which fits inside, which differences in level each protrude inwardly by a distance equal to the thickness of the first plate 111a, whereby the outer wall surface of the tube 101 is made substantially level thereover. A gap which is formed between the outer wall surface of the tube 101 and a core plate, when the tube is passed through the core plate, can be as small as possible whereby the brazing properties can be improved.

Abstract: A tube 101 is constituted by a pair of plates 111a, 111b which are fitted with each other in such a manner as to put an inner fin 101b between the plate 111a and the plate 111b. Differences in level 111c are formed on the second plate 111b, which fits inside, which differences in level each protrude inwardly by a distance equal to the thickness of the first plate 111a, whereby the outer wall surface of the tube 101 is made substantially level thereover. A gap which is formed between the outer wall surface of the tube 101 and a core plate, when the tube is passed through the core plate, can be as small as possible whereby the brazing properties can be improved.

Abstract: A tube is constituted by a pair of plates which are fitted with each other in such a manner as to put an inner fin between the plates. Differences in level are formed between the two plates, which differences in level is compensated by either a tapered wall or a stepped wall, whereby the outer wall surface of the tube is made substantially level thereover. A gap which is formed between the outer wall surface of the tube and a core plate, when the tube is passed through the core plate, can be as small as possible whereby the brazing properties can be improved.

Abstract: A tube 101 is constituted by a pair of plates 111a, 111b which are fitted with each other in such a manner as to put an inner fin 101b between the plate 111a and the plate 111b. Differences in level 111c are formed on the second plate 111b, which fits inside, which differences in level each protrude inwardly by a distance equal to the thickness of the first plate 111a, whereby the outer wall surface of the tube 101 is made substantially level thereover. A gap which is formed between the outer wall surface of the tube 101 and a core plate, when the tube is passed through the core plate, can be as small as possible whereby the brazing properties can be improved.

Abstract: A heat exchanger includes fins (111) having a plurality of sets of two louvres (111c) substantially triangular in shape which are formed in such a manner that the distance from a flat plate portion (111a) increases progressively downstream in the gas flow direction. The two louvres (111c) of each set are arranged inwardly slanted along the gas flow direction, so that a vertical swirl is generated to draw the gas flow between the louvres (111c). The gas flowing in the vicinity of the flat plate portion (111a) and the gas flowing in the vicinity of a vertical plate portion (111b) are thus accelerated. As a result, the heat conductivity of the gas and the fins (111) is improved and the particulate matter attached on the surface of the fins (111) can be blown off, thereby preventing the clogging of the fins (111).

Abstract: A tube 101 is constituted by a pair of plates 111a, 111b which are fitted with each other in such a manner as to put an inner fin 101b between the plate 111a and the plate 111b. Differences in level 111c are formed on the second plate 111b, which fits inside, which differences in level each protrude inwardly by a distance equal to the thickness of the first plate 111a, whereby the outer wall surface of the tube 101 is made substantially level thereover. A gap which is formed between the outer wall surface of the tube 101 and a core plate, when the tube is passed through the core plate, can be as small as possible whereby the brazing properties can be improved.

Abstract: A heat exchanger is disclosed, in which a plurality of sets of two louvres (111c) substantially triangular in shape are formed in such a manner that the distance from a flat plate portion (111a) increases progressively downstream in an EGR gas flow. The two louvres (111c) of each set are arranged inwardly slanted along the exhaust gas flow, so that a vertical swirl is generated to draw the EGR gas flow between the louvres (111c). The EGR gas flowing in the vicinity of the flat plate portion (111a) and the EGR gas flowing in the vicinity of a vertical plate portion (111b) are thus accelerated. As a result, the heat conductivity of the EGR gas and the fins (111) are improved and the particulate flatter attached on the surface of the fins (111) can be blown off, thereby preventing the clogging of the fins (111).

Abstract: An exhaust gas heat exchanger includes exhaust gas tubes through which exhaust gas generated by a combustion flows and cooling water tubes through which cooling water for cooling exhaust gas flows. Plural segments of offset fins are disposed within each exhaust gas tube to be arranged staggeringly in a tube longitudinal direction. The cooling water tubes communicate with each other through cooling water communication passages disposed on both end sides of each exhaust gas tube in the tube longitudinal direction at diagonal positions when being viewed from a minor-diameter direction of each exhaust gas tube. The segments are tilted relative to the tube longitudinal direction toward a side opposite to a diagonal line (L1) connecting the cooling water communication passages. Thus, a cross angle between the tilt direction of the segments and a main flow of the exhaust gas becomes smaller, and a pressure loss in the exhaust gas tubes is reduced.