| 摘要 |
PURPOSE:To enhance safety of an engine, by letting abnormal pressure in a cooling system escape to the outside of the system when pressure in the cooling system is abnormally raised. CONSTITUTION:When an engine is operated at low speeds and under high load, or an electric fan 8 is reduced in its performance, pressure in a cooling system and wall temperature are raised. The pressure in the cooling system and the wall temperature are detected, a reducing valve 13 is closed by a control circuit 10B according to a signal from a pressure sensor 11, thereby letting the pressure in the cooling system escape into an exhaust pipe 5. Accordingly, it is possible to prevent thermal deformation of a cylinder head 2 and a cylinder bore due to increase in the wall temperature, and also prevent breakage of a radiator 6. |
