| 摘要 |
PROBLEM TO BE SOLVED: To provide an EGR gas cooling system which prevents degradation of its cooling performance by reducing accumulation quantity of condensed water generated by cooling EGR gas. SOLUTION: This EGR gas cooling system comprises an upstream EGR gas chamber, a downstream EGR gas chamber, multiple heat-transfer tubes which connect the internal space of both EGR gas chambers and in which EGR gas flows, and cooling water passage formed around the heat-transfer tubes. The EGR gas chambers are so formed that the maximum level of condensed water which may accumulate in the EGR gas chambers is flush with the lowest point of the peripheral edge inside the water-surface side opening end of the heat-transfer tube located vertically lowest among all the heat transfer tubes, or the maximum level of condensed water which may accumulate in the EGR gas chambers is located vertically below the lowest point of the peripheral edge inside the water-surface side opening end of the heat-transfer tube located vertically lowest among all the heat transfer tubes when the EGR gas cooling system is mounted on a vehicle.
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