Patent ID: 7798206

Claim:
A heat exchanger comprising: a pair of header tanks spaced apart from each other; a plurality of flat heat exchange tubes which are disposed between the two header tanks at predetermined intervals along a longitudinal direction of the header tanks with their width direction coinciding with an air flow direction and whose opposite end portions are connected to the corresponding header tanks; and a plurality of fins each disposed between the adjacent heat exchange tubes, wherein each header tank includes a box-shaped tank body which opens toward the other header tank, and a header plate joined to an open end portion of the tank body and closing the opening of the tank body; the tank body and the header plate are each formed by means of bending a metal blank; the tank body includes a rectangular top wall, a pair of first side walls extending from one pair of parallel sides of the top wall, and a pair of second side walls extending from the other pair of parallel sides of the top wall; of each pair of the first and second side walls of the tank body located adjacent to each other, the first side wall has a joining portion which is formed integrally with the first side wall via a rounded connection portion and which extends along the inner surface of the second side wall; the header plate includes a rectangular closure wall having a plurality of tube insertion holes, a pair of first side walls extending from one pair of parallel sides of the closure wall and extending along the outer surfaces of opening-side end portions of the first side walls of the tank body, and a pair of second side walls extending from the other pair of parallel sides of the closure wall and extending along the outer surfaces of opening-side end portions of the second side walls of the tank body; opposite end portions of the heat exchange tubes are inserted into the tube insertion holes of the header plate and are joined to the header plate; a first-side-wall-side end portion of each second side wall of the tank body is curved along an outer surface of the corresponding rounded connection portion to thereby form a first bent portion; a first-side-wall-side end portion of each second side wall of the header plate is curved along the first bent portion of the tank body to thereby form a second bent portion; and the first side walls of the header plate have respective deformation portions which enter recesses formed between the outer surfaces of the rounded connection portions of the tank body and tip end surfaces of the first bent portions.