| 摘要 |
PROBLEM TO BE SOLVED: To prevent a cooling medium from being boiled and at the same time to increase the amount of heat exchange of an EGR gas by providing a plurality of cooling zones of the EGR gas, and at the same time introducing the cooling medium with a different temperature to each cooling zone. SOLUTION: The both end parts of a group of heat transfer pipes 2 are fixed to a sheet metal tube sheet 3 inside a conduct 1, and the tube sheet 3 is arranged by sealing an outer periphery onto the inner wall of the conduit 1. Then a partition board 5 is fixed at the both end parts of the inside of the conduit 1, the inlet side of an EGR gas of the inside of the conduit 1, a center part, and the outlet side of the EGR gas are set as a first cooling zone 1-1, a second cooling zone 1-2, and a third cooling zone 1-3, respectively, at the same time, the first cooling zone 1-1 is connected to the third cooling zone 1-3 by a tie piping 6, and an inlet 1-1a of a low-temperature cooling medium, an outlet 1-3b of the low-temperature cooling medium, and an inlet 1-2a and an outlet 1-2b of an engine coolant are provided in the first cooling zone 1-1, the third cooling zone 1-3, and the second cooling zone 1-2, respectively.
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