Abstract: A method of producing a tube which has a tube body portion constituting an outer hull of flow passages, and flow passage dividers for dividing the flow passages, comprising a roll forming process to form the tube, a cutting process to cut the tube to a predetermined length after the roll forming process, and a brazing process to braze the tube contact portions of the flow passage dividers to the inner surface of the tube body portion after the cutting process. The cutting process forms a slit in the tube, and so as to concentrate a stress on the slit, thereby to cut the tube starting from the slit. The slit is formed in only the tube body portion between the tube body portion and the flow passage dividers or formed ranging from the tube body portion to the tube contact portions of the flow passage dividers.

Abstract: In a tube (4) for a heat exchanger comprising a flat pipe (16) whose both ends are opened and in which a flow path (15) for a heat exchanging medium is formed, and an inner fin (17) arranged in the flow path (15), wherein said flat pipe (16) is constituted of a sheet of material for a flat pipe, the inner fin is constituted of two opposing flat plate portions (17b, 17c) connected along one of side edges of said flat pipe (16) and formed in a flat plate shape so as to be in contact with an inner surface of the said flat pipe (16), and projection portions (17d) which are projected from at least one of the flat plate portions (17b, 17c) and whose tops are in contact with the other opposing flat plate portion (17b, 17c). It is preferred that the projection portions (17d) are projected from both of the flat plate portions (17b, 17c) toward the opposing flat plate portion, and the opposing tops are made come in contact with each other.

Abstract: In a tube (4) for a heat exchanger comprising a flat pipe (16) whose both ends are opened and in which a flow path (15) for a heat exchanging medium is formed, and an inner fin (17) arranged in the flow path (15), wherein said flat pipe (16) is constituted of a sheet of material for a flat pipe, the inner fin is constituted of two opposing flat plate portions (17b, 17c) connected along one of side edges of said flat pipe (16) and formed in a flat plate shape so as to be in contact with an inner surface of the said flat pipe (16), and projection portions (17d) which are projected from at least one of the flat plate portions (17b, 17c) and whose tops are in contact with the other opposing flat plate portion (17b, 17c). It is preferred that the projection portions (17d) are projected from both of the flat plate portions (17b, 17c) toward the opposing flat plate portion, and the opposing tops are made come in contact with each other.

Abstract: A heat exchanger having tubes 21 for flowing a medium and tanks 3 each formed of an end plate 32 having tube insertion holes 5 for connection of the tubes and a tank plate 31 connected to the end plate, which are assembled and brazed in a heating furnace, wherein the tank plate 31 is formed of a plate provided with brazing materials R1, R2, and at least one of the tank plate 31 and the end plate 32 is provided with separator portions 311, 321 not provided with the brazing material for prevention of the brazing material from outflowing. The tank 3 has partition plates 7 for dividing the interior, the inner surface of at least one of the tank plate 31 and the end plate 32 is clad with the brazing material, and the partition plates 7 are formed of a bare material not clad with a brazing material.

Abstract: A heat exchanger is comprising a core which is consisting of tubes provided with medium passages and fins fitted to the tubes, and tanks to which ends of the tubes are connected, wherein the tube (2) is formed to have a flat cross-sectional shape by joining ends of one or two plates, the ends of the plates have a contact portion which is formed by bending at least one of the plate ends a plurality of times and overlaying the one end on the other end, and the contact portion is provided with a joint portion (2c) which is formed by placing a part (2e) of the contact portion on the top or bottom flat surface and mutually engaging the both ends of the plate.