| 摘要 |
PURPOSE:To prevent increase in the number of fan revolutions by reducing the number of engine revolutions to reduce a fan noise by controlling a flow control valve to maintain fan control quantity correspondent to the number of engine revolutions before decelerating an engine during its low speed operation. CONSTITUTION:Working liquid discharged from a pump 30 driven by an internal combustion engine 36 is supplied to a hydraulic motor 16, which rotates a cooling fan 10 to cool a radiator 12. The pump 30 is additionally provided with a flow control valve 22 which controls a supply flow rate and a return one in mutually oppose relationship according to the duty ratio of a pulse signal applied to an electromagnetically actuating section to increase or decrease the above-mentioned flow rates. The flow control valve 22 is controlled through a control device 40 on outputs given by a water temperature sensor 42 and a sensor 44 for the number of engine revolutions. In controlling the valve 22, a fan control quantity is determined to maintain the fan control quantity based on the number of engine revolutions before decelerating the engine during its low speed operation to control the valve 22. |
