Patent ID: 7219720

Claim:
A fluid passing flat hollow body comprising: an upper flat plate and a lower flat plate elongated laterally and spaced apart as positioned one above the other; and a channel forming body interposed between and brazed to the upper and lower flat plates, the channel forming body comprising two straight side bars extending laterally and arranged between the upper and lower flat plates respectively at front and rear opposite side edges thereof, an intermediate bar extending laterally and disposed between and spaced apart from the two side bars, two heat transfer area increasing portions each interconnecting the intermediate bar and each of the side bars integrally therewith and positioned at an intermediate portion of the height of the bars, and plural end bars extending forwardly or rearwardly inward from right ends of the respective side bars integrally therewith and having respective inner ends butting on and brazed to front and rear opposite side faces of a right end of the intermediate bar, wherein the intermediate bar has a left end portion cut out therefrom, the two heat transfer area increasing portions have respective right end portions cut out therefrom, each of the upper and lower flat plates has holes formed in a right end portion thereof respectively on front and rear opposite sides of the intermediate bar, the upper and lower flat plates provide upper and lower walls, respectively, a left end portion of each of the upper and lower flat plates is bent toward the other flat plate, with the bent portions lapped over and brazed to each other, to thereby provide a left wall portion of a peripheral wall, the side bars of the channel forming body providing respective front and rear opposite side wall portions of the peripheral wall, the end bars of the channel forming body providing a right wall portion of the peripheral wall, the peripheral wall interconnects peripheral edges of the upper and lower walls, the intermediate bar provides a partition wall dividing the interior of the peripheral wall into front and rear two channels extending laterally, each of the upper and lower walls has the two holes formed in the right end portion thereof respectively on front and rear opposite sides of the partition wall and spaced apart transversely of the upper or lower wall for causing the respective channels to communicate with the outside therethrough, and the left end portion of the partition wall is cut out to hold the two channels in communication with each other.