WORKING FLUID COOLING CONTROL SYSTEM OF CONSTRUCTION MACHINE

A working fluid cooling control system for a construction machine is provided which is capable of improving the cooling performance before a rise in temperature of a working fluid, thereby preventing a rise in temperature of the working fluid, making it possible to diminish failures of hydraulic devices and improving machine lives thereof, thus preventing the occurrence of problems such as a worsening of noise and of fuel efficiency. A controller 100 inputs signals from a traveling motor speed pickup 101, a pressure sensor 102, a signal receiving line 103a of an option selecting switch 103 and a temperature sensor 104, then performs predetermined arithmetic processing and controls proportional solenoid valves 105 and 106. The pressures controlled by those solenoid valves are compared with positive control command pressures in shuttle valves 109 and 110 and the higher pressures are conducted to tilt control mechanisms 13 and 14. In this way, in the case of an operation pattern corresponding to a rise in temperature of the working fluid, minimum tilting angles of hydraulic pumps 11 and 12 are increased to increase an average flow rate of the working fluid passing through an oil cooler 40, thereby increasing an average heat discharge amount and reducing an equilibrium temperature of the working fluid.