| 摘要 |
PROBLEM TO BE SOLVED: To precisely diagnose the abnormality of a flow regulating valve capable of adjusting the flow rate (bypass flow rate) of cooling water carried bypassing a radiator. SOLUTION: During the warming-up of an engine 11, the opening of the flow regulating valve 18 is controlled so that the radiator flow rate B is 0, and the bypass flow rate A is smaller than the bypass flow rate A after completion of warming. Accordingly, the bypass flow rate is minimized to minimize the circulating flow rate of the cooling water in a state where the heat radiation of the cooling water by the radiator 13 is almost eliminated, whereby the cooling efficiency (the radiation efficiency of cooling water) of the engine 11 is reduced to raise the rising rate of cooling water temperature. During the warming-up of the engine 11, the cooling water temperature is estimated based on a parameter related to the heating value of the engine 1 and a parameter related to the radiation quantity of the cooling water, and the estimated cooling water temperature is compared with the actual cooling water temperature detected by a water temperature sensor 19 to diagnose the abnormality of the flow regulating valve 18. COPYRIGHT: (C)2004,JPO
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