Too high oil temperature is a common fault of hydraulic system of excavators. The reasons are complex and often difficult to handle. In view of the excessive oil temperature of the XEM220LC hydraulic excavator, the following analysis can be made and solutions are put forward.
(1) the heat sink efficiency of the radiator is low.
The heat sink area can be increased by 8cm2, and the temperature difference between the inlet and outlet of the radiator can be increased from 7 C to 10 C, and the effect is very obvious.
(2) the one-way valve on the hot return oil road is out of order.
The oil return pressure of the existing system is 0.3MPa and the oil cooler protection pressure is 0.2MPa. In principle, the back pressure of the oil return should be as low as possible when meeting the requirements of the back pressure of the system. The oil temperature is too high, which may be: the resistance of the radiator is greater than the protection pressure, so that the hot oil of the return oil road is not directly back to the tank by the radiator; the system cleanliness is poor, the one-way valve is stuck with the dirt, the valve core is in a constant position, the radiator does not play a role, and the opening pressure of the one-way valve can not be guaranteed. Under the premise of meeting the back pressure of the system, the one-way valve of 0.30MPa can be changed to the one-way valve of 0.15MPa, and the protection pressure of the oil cooler will be increased to 0.35MPa.
(3) the air duct arrangement of the engine is not reasonable.
The irrationality of the existing wind tunnel is:
(1) the air intake of the radiator is not enough. A long slot can be opened on the side door to increase intake air volume.
There is a gap between the radiator and the engine, and no effective seal is carried out, and the front of the weight block is concave and the hot air is formed to form eddy current, resulting in poor heat dissipation. The sponge can be glued between the radiator and the engine for sealing, and the front surface of the counterweight block is changed from a concave surface to a plane.
(3) the main pump of the hydraulic system is short of heat insulation plates, causing the hot air from the engine to blow directly to the rear side wall of the hydraulic oil tank, causing the oil temperature in the fuel tank to rise. It can be improved by adding heat insulation board.
(4) the heat dissipation of the radiator's air duct or the blockage of the oil passage cause the wind resistance to increase and the heat dissipation effect to be poor.
We should adjust the lodging fins in time and clean up the blockage of the air duct. We must regularly wash the water with certain pressure to ensure that the air passage is unblocked.
(5) improper selection of hydraulic oil brand or poor oil quality.
The low viscosity of hydraulic oil will increase the internal leakage, reduce the efficiency and produce heat; the viscosity is too high and the loss of fluid pressure increases, which can produce a large amount of heat and cause the oil temperature to be too high. At the same time, poor oil quality is easy to emulsify, which can aggravate the damage of hydraulic components.
After being improved, the temperature difference between inside and outside walls of the fuel tank dropped from 8 degrees C to 1-2 degrees C.
