| 摘要 |
PROBLEM TO BE SOLVED: To utilize cooling water of an internal combustion engine, so that EGR gas can be properly cooled, concurrently prevent deterioration of cooling ability and overcooling of EGR gas in the internal combustion engine. SOLUTION: In an EGR gas cooler 20 provided in an EGR passage, cooling water of an internal combustion engine 1 is circulated through a cooling water passage 26, 28. By a first EGR gas temperature detection means 30, a temperature of EGR gas before passing the EGR gas cooler is detected, by a second EGR gas temperature detection means 32, a temperature of EGR gas after passing the EGR gas cooler is detected, and by a cooling water temperature detection means 42, a temperature of cooling water returned back from the EGR gas cooler to the internal combustion engine is detected. Based on these detection information, an opening of a cooling water control valve 40 is controlled to a proper value. |
