| 摘要 |
PURPOSE:To prevent the local rise in temperature of a cylinder block and prevent overheating, etc. by providing a means of allowing a cooling water to flow through a cooling water passage which passes through said cylinder block, in response to the high output zone operation of an engine. CONSTITUTION:A first cooling water passage 3 which passes through a cylinder block 2 and a second cooling water passage 5 which passes through a cylinder head 4 are provided in an engine body 1. Cooling water from a water pump 6 passes through each of the cooling water passages 3, 5, and are confluent in a confluent passage 7, to reach a radiator 8. In this construction, a passage 12 which bypasses a second thermostat valve 11, is provided on the first cooling water passage 3, and a valve 13 is provided in this passage 12. This valve 13 is driven by a control unit 15 based on a signal from a sensor 14 which detects an intake-pipe negative pressure, etc. Thereby, when the operation of an engine is shifted to a high output zone operation, the valve 13 is opened to cool the cylinder block 2. |
