For such faults, generally speaking, the internal analysis outside the hydraulic system should be the first. The internal reason is mainly caused by unreasonable system design. Such as unreasonable matching between components, too thin pipeline channel, many elbows, small bending radius, insufficient oil tank volume and other factors.
< 1) heating of hydraulic system caused by external causes
For example, the engine of the hydraulic pump of Volvo ec210b excavator is connected through the damping damper in the damping box. When dealing with the heating fault of the hydraulic system of an excavator, it was found that the oil level in the damping box was much higher than the observation oil level screw (generally about 1.5L), and these excessive oil generated a lot of heat and transferred to the hydraulic pump during the rotation of the damping damper, resulting in the heating of the system.
At this time, the fault can be eliminated after the oil in the damping box is drained to the standard oil level. There are two reasons for the high oil level in the damping box: first, the operator refuels blindly; Second, the oil seal at the shaft end of the hydraulic pump is aging, resulting in the leakage of hydraulic oil. The latter should remove the bolt and replace the oil seal of the hydraulic pump.
< 2) the oil temperature is too high due to poor heat dissipation performance of radiator
The main forms of poor heat dissipation performance of radiator are: deformation or blockage of external heat dissipation fins, poor cooling effect; Insufficient cooling fan; The internal pipe of hydraulic oil radiator is blocked. In addition to visual judgment, the first two can also be known from the small change in the temperature difference between the upper and lower tubes of the radiator. At this time, the heat sink should be cleaned and the fan belt should be fastened. To judge the blockage of the internal pipeline of the hydraulic oil radiator, install a pressure gauge at the inlet and outlet of the radiator to check the pressure difference between them. The oil temperature is about 450C, and the pressure difference below 0.12mpa is normal. If it is higher than 0.12mpa, it indicates that the oil pipe is seriously blocked, and the upper and lower covers of the radiator should be removed to dredge the pipeline.
< 3) hydraulic oil overheating caused by failure of check valve of hydraulic return oil filter element
It can be seen from the schematic diagram of the hydraulic system that the check valve of the oil return filter element of the hydraulic system and the hydraulic oil radiator are connected to the outlet of the oil return filter element (see the schematic diagram of Volvo ec210b hydraulic system). Its function is to automatically open when the pressure difference of the oil return radiator is more than 0.185mpa, and short-circuit the radiator to form an oil return path. In actual work, because the valve is installed at the bottom of the oil return filter element, it is difficult to check and maintain. In addition, some operators choose the hydraulic oil improperly, do not change the oil for a long time and disrepair for a long time, resulting in serious oil pollution, resulting in the valve stuck in the normally open position (others remove the valve without authorization). Therefore, the oil return radiator does not play the role of heat dissipation, which is bound to cause excessive oil temperature. Check whether the valve is stuck every time you change the hydraulic oil.
