| 摘要 |
PROBLEM TO BE SOLVED: To perform both of cooling and warming of working fluid, obtain a high warming effect, and prevent operation of a hydraulic actuator from being hindered during warming.SOLUTION: A hydraulic circuit of a construction machine includes: a hydraulic actuator circuit A having a main pump 1 as a hydraulic power source; a fan motor circuit B having a pump 3 for a fan as a hydraulic power source and configured to drive a fan motor 4; a working fluid tank 5 shared in the circuits A, B; a relief valve 10 provided in the fan motor circuit B and used as a warming valve; and a selector valve 12 configured to change over a circuit state. The hydraulic circuit, by change over the selector valve 12 with a controller 13 among a cooling position a, an intermediate position b and a warming position c, changes over to a cooling state of cooling an oil cooler 9 while rotating a fan 8, a state of not performing cooling and warming, or a warming state of operating the relief valve 10.SELECTED DRAWING: Figure 1 |
