| 摘要 |
PROBLEM TO BE SOLVED: To restrain promotion of deterioration of a catalyst in a purifying device by providing a bypass passage for bypassing a heat exchanger on a cooling water circulation circuit, providing a three-way selector valve on either two connecting parts of the cooling water circulation circuit and the bypass passage, and switching the valve according to the detected result of the exhaust gas temperature. SOLUTION: A lubricating oil cooler 1 is provided with a piping 1a for recovering lubricating oil which has lubricated a sliding part of an engine, and lubricating oil cooled in it is distributed from a piping 1b to respective sliding parts. In this case a temperature detecting unit 6 is arranged on the piping 1b, and a detected signal is input to a comparator 12 and compared with the specified temperature. A temperature detecting unit 8 is provided upstream of a purifying device 5 and on an exhaust pipe 7 connected to a supercharger 4, and a detected signal is input to a comparator 13 and compared with the specified temperature. The switching state and the opening of a three-way selector valve 9 provided on one end of a bypass pipe 20 detouring a heat exchanger 3 in a cooling water circulation circuit 90 is controlled according to the compared results of respective comparators 12, 13, and the exhaust gas temperature is maintained to the specified temperature.
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