Cooling water circuit system

摘要

A cooling water circuit system for an engine includes a radiator bypass passage through which cooling water of the engine bypasses a radiator, a heat exchanger disposed in the radiator bypass circuit to perform heat exchange between the cooling water and lubricant oil of an automatic transmission, and a radiator downstream passage through which the cooling water from the radiator flows into the heat exchanger. Further, a flow adjusting unit is disposed at a join portion where the radiator bypass passage and the radiator downstream passage are joined, to adjust a flow ratio between the cooling water flowing from the radiator downstream passage to the heat exchanger and the cooling water flowing from the radiator bypass passage to the heat exchanger. The flow adjusting unit is controlled by a control unit in accordance with the temperature detected by the temperature detection unit.