| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique for increasing drive efficiency of parts forming a cooling device such as a water pump, an electronic thermostat and an electric fan and for improving fuel consumption. SOLUTION: A plurality of electric water pumps are provided and at least one electric water pump among them is formed to have a different rating from ratings of the other electric water pumps. In the case where the two electric water pumps different in rating are provided, the pump of the smaller rating is driven when a demand circulation flow rate of cooling water required according to operation condition of the internal combustion engine is smaller than a first predetermined rate, when the demand circulation flow rate is larger than the first predetermined rate and smaller than a second predetermined rate, the pump of the larger rating is driven and when the demand circulation rate is larger than the second predetermined rate, the two pumps are driven together. COPYRIGHT: (C)2006,JPO&NCIPI
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