| 摘要 |
PROBLEM TO BE SOLVED: To provide a cooler of an engine by which the exhaust can be cooled with a simple structure in the high load of the engine. SOLUTION: This cooler comprises a by pass passage 20 passing around an exhaust port, a communicating path 30 for communicating the engine inlet side 26 of a coolant circulation path and the bypass passage 20, and a communicating path valve 32 for opening and closing the communicating path 30. In the warming-up operation, the coolant is not passed through a radiator 18, but passed through the bypass passage 20 to rapidly terminate the warming-up. On this occasion, the coolant is warmed by the exhaust flowing in the exhaust port to accelerate the rise of temperature of the coolant. After the warming-up, the bypass passage 20 is closed, and the coolant is made to flow into the radiator 18. Further in the high load operation, the communicating path valve 32 is opened, and the coolant is made to flow into both of a path 12 in the engine body 10 and the by-pass passage 20. The exhaust flowing in the exhaust port is cooled by the coolant flowing in the by pass passage 20.
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