| 主权项 |
1. A heat exchanger comprising:
a plurality of flat heat exchange tubes disposed at predetermined intervals in a thickness direction of the tubes in such a manner that their longitudinal directions coincide with one another and their width directions coincide with an air-flow direction; and two header tanks disposed at opposite longitudinal ends of the heat exchange tubes in such a manner that their longitudinal directions coincide with a direction in which the heat exchange tubes are juxtaposed, opposite end portions of the heat exchange tubes being connected to the corresponding header tanks, each of the header tanks being composed of a tubular tank body which has openings at opposite ends thereof, and closing members which are brazed to the opposite ends of the tank body so as to close the openings, the tank body having a plurality of tube insertion holes which are formed at predetermined intervals in a longitudinal direction of the tank body and each of which is an elongated hole whose longitudinal direction coincides with the air-flow direction, protrusion portions which project toward an inner space of the tank body being formed along edges of each tube insertion hole which are located on opposite sides in a width direction of the tube insertion hole and which face each other, and an end portion of each heat exchange tube being inserted into the corresponding tube insertion hole and being brazed to a portion of the tank body around the tube insertion hole and the protrusion portions, wherein each heat exchange tube is formed of a first brazing sheet having a core material and a brazing material covering an outer surface of the core material; the tank body of each header tank is formed of a second brazing sheet having a core material and a brazing material covering an outer surface of the core material and being lower in flowability than the brazing material of the first brazing sheet used to form the heat exchange tube; each of the protrusion portions has a projection height equal to or greater than a thickness of a circumferential wall of the tank body and has a thickness which decreases gradually toward a projecting end thereof; in a region of a surface of each protrusion portion facing the corresponding heat exchange tube, the region having a predetermined width as measured from the projecting end, the core material of the second brazing sheet is brazed to the core material of the first brazing sheet by means of the brazing material covering the outer surface of the first brazing sheet; in a region of the surface of each protrusion portion facing the corresponding heat exchange tube, the region remaining after exclusion of the brazed portion, a distance between the core material of the second brazing sheet and the core material of the first brazing sheet increases gradually from a side closer to the brazed portion toward the outside of the tank body, and a brazing material accumulation space is formed between the core materials of the two brazing sheets; and portions of the core materials of the two brazing sheets which form the brazing material accumulation space are brazed to each other by means of a fillet formed in the brazing material accumulation space, the fillet being formed of a mixture of the brazing material covering the outer surface of the first brazing sheet and the brazing material covering the outer surface of the second brazing sheet. |
