Patent ID: 6076488
Filing Date: 2000-06-20
Classification: F01P

Abstract:
A cooling device for a construction machine, the construction machine having an engine, and a hydraulic circuit in which hydraulic oil circulates, the cooling device including:a radiator for cooling an engine coolant flow,an oil cooler for cooling the hydraulic oil circulating in the hydraulic circuit,a cooling fan for blowing air onto said radiator and said oil cooler, the radiator and oil cooler being in line one with another and disposed in an air passage located separately from the engine and such that with respect to air blowing in a first direction in the air passage, the radiator is downstream of the oil cooler, and with respect to air blowing in an opposite direction in said air passage, the radiator is upstream of said oil cooler,said cooling fan having a forward rotation operation mode in which air is blown therewith in the first direction, a reverse rotation operation mode in which air is blown therewith in said opposite direction, and a further operation mode in which said cooling fan is stopped,an oil operated motor for driving the cooling fan,a control device comprising a three position change valve for effecting cut off and feed of oil to the oil operated motor, a first change valve position corresponding to cooling fan forward operation mode, a second change valve position corresponding to cooling fan reverse rotation operation mode, and a third position corresponding to said cooling fan further operation mode,a controller for controlling shifting of said three position change valve responsive to sensed respective ones of conditions of outside air temperature, engine coolant temperature, and hydraulic circuit hydraulic oil temperature, anda respective plurality of separate sensors connected to the controller for detecting the said respective ones of outside air temperature, engine coolant temperature, and hydraulic circuit hydraulic oil temperature conditions,said controller, on a start of the engine and where outside air temperature, engine coolant temperature, and hydraulic circuit hydraulic oil temperature are, respectively, lower than a given temperature of each, is effective to maintain the change valve in third position until engine coolant is warmed by engine operation to and above the given engine coolant temperature whereupon said controller further is effective to shift the change valve to second position for operating the cooling fan in reverse rotation operation mode so that cooling air warmed on passing the radiator is used to warm hydraulic circuit hydraulic oil in the oil cooler and to remove any debris lodged in the radiator and oil cooler.