| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability of a soldered part by chamfering many holes formed on a tube sheet to be fitted with the end parts of many hole tubes, so as to form recessed parts of triangular section outside the tube sheet at inserting the tubes, and soldering so as to bury recessed parts. SOLUTION: Tube sheets 2 are arranged on the inside of both ends of a cylindrical main body 1 of an EGR cooler, and the outer circumferences are fixedly fitted to the inner circumference of the main body 1. Tubes 3 are respectively inserted into many holes 4 drilled on the tube sheet 2, and they are fixedly fitted by soldering. In this case, on the gas passage side of the holes 4 drilled on the tube sheet 2, chamfering parts 2a are formed so as to form recessed parts of triangular section by the tube sheet 2 and the tubes 3 inserted in the respective holes 4, and soldering is executed so as to bury the recessed parts to fix the tubes 3. Hereby, solder is prevented from penetrating the water side of the tube sheet 2, and reliability of the soldered part is improved.
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