A vehicle, in which cooling water is circulated in an engine using an electric water pump to keep the engine at a suitable temperature while the engine is driven to run the vehicle has been known. When the engine stops and the electric water pump is stopped simultaneously, it follows that the cooling water circulation stops while the engine is not sufficiently cooled yet. Therefore, the cooling water may possibly be overheated and boiled. If the electric water pump is operated after the engine stops in order to prevent boiling of cooling water, power consumption undesirably increases and load to the battery also increases. A solution to such a problem is disclosed, for example, in Japanese Patent Laying-Open No, 2005-90236 (Patent Document 1).
The cooling device for an internal combustion engine disclosed in Japanese patent Laying-Open No. 2005-90236 includes: an electric water pump for circulating cooling water, of which circulation flow rate is variable, in the internal combustion engine and in a heat exchanger; a detecting unit detecting information related to cooling water temperature; and a control unit controlling the flow rate of cooling water circulated by the electric water pump, based on the information related to cooling water temperature detected by the detecting unit, after the internal combustion engine is stopped.
By the cooling device for an internal combustion engine disclosed in Japanese Patent Laying-Open No. 2005-90236, the flow rate of cooling water circulated by the electric water pump is controlled even after the internal combustion engine is stopped. Therefore, boiling of cooling water after the stop of internal combustion engine can be prevented. Further, since the flow rate of cooling water circulated by the electric water pump is controlled based on the information related to cooling water temperature, the time and amount of operation of electric water pump can be minimized. As a result, the power consumed by electric water pump can be reduced, and the load to the battery can also be reduced.    Patent Document 1: Japanese Patent Laying-Open No. 2005-90236