Patent ID: 7341099

Claim:
A flat tube comprising: first and second flat walls opposing each other; first and second side walls connecting opposite side edges of the first and second flat walls; and a plurality of reinforcing walls connecting the first and second flat walls and extending in a longitudinal direction of the first and second flat walls, the reinforcing walls forming a plurality of fluid channels between the first and second flat walls, wherein the first side wall comprises a joint portion connecting the first and second flat walls and forming a hairpin shape with the first and second flat walls, the second side wall comprises a side wall forming portion projecting from the first flat wall and a side wall forming portion projecting from the second flat wall, respectively, and the side wall forming portion in the first flat wall is intimately fitted with the side wall forming portion in the second flat wall, the reinforcing walls comprise reinforcing wall forming portions projecting from the first flat wall and reinforcing wall forming portions projecting from the second flat wall, respectively, the reinforcing wall forming portions in the first and second flat walls have engaging portions, respectively, the engaging portions are configured to be intimately fitted with each other when the reinforcing wall forming portions in the first flat wall are butted against the reinforcing wall forming portions in the second flat wall, the reinforcing wall forming portions in the first flat wall are brazed to the reinforcing wall forming portions in the second flat wall, and the first and second flat wall forming portions, the side wall forming portions and the reinforcing wall forming portions comprise a metal plate comprising an aluminum brazing sheet, the side wall forming portions and the reinforcing wall forming portions are formed on a brazing material bearing surface of the aluminum brazing sheet, and the side wall forming portions and the reinforcing wall forming portions include brazing material layers, respectively.