COOLING FAN DRIVING DEVICE AND FAN ROTATION NUMBER CONTROL METHOD

摘要

The invention provides a cooling fan driving device and the a fan rotational speed control method using the device capable of reducing uneconomical waste of flow volume of pressurized oil discharged from a hydraulic pump when the rotational speed of a cooling fan is increased to the target rotational speed. The target rotational speed of the cooling fan is set at a target rotational speed setting portion 22 of a controller 7 based on temperature of refrigerant and hydraulic oil and the rotational speed of an engine. An acceleration pattern for increasing the rotational speed of the cooling fan to the target rotational speed is set at an acceleration pattern setting portion 23 based on the rotational speed of the cooling fan, the target rotational speed set at the target rotational speed setting portion 22, and magnitude of force due to inertia of the cooling fan and the hydraulic motor which drives the cooling fan. The rotational speed command value calculation portion 24 performs control so that pressurized oil is supplied to the hydraulic motor at a flow rate required when the hydraulic motor is controlled to be accelerated based on the acceleration pattern. Thus, it is possible to reduce relief flow volume to be wasted without being consumed for the acceleration control of the hydraulic motor.