Created on:2021-09-01 14:12

Port equipment_ Maintenance of car dumper -- problems and improvement of respiratory system in hydraulic station

Port equipment_ Maintenance of car dumper -- problems and improvement of respiratory system in hydraulic station

During the use, the following main problems were found.

① A large amount of oil is mixed with air for a long time, resulting in unstable action of hydraulic cylinder and accelerating oil aging. When the hydraulic cylinder acts, the internal volume of the oil tank changes through the breathing of the built-in respirator connected with the main oil tank. The respirator is directly connected with the oil tank, the internal air and oil are in direct contact for a long time, and the hydraulic station frequently reverses with the dumper. The air and oil are in a dynamic reciprocating mixing state, and a large amount of air dissolves into the oil, accelerating the oxidation and deterioration of the oil, and causing the unstable action of the hydraulic cylinder.

② There is a large amount of intake air in the system. When the pressure is too high, air and oil are frequently ejected from the preloaded air filter. When the hydraulic cylinder is extended, the oil in the oil tank is reduced and air supplement is required, the air in the respirator cannot be supplemented in time due to the opening of the change-over valve and the insufficient design flow of the pipeline. The system frequently supplements air to the oil tank through the air filter to make a large amount of air intake in the oil tank; When the hydraulic cylinder retracts and the oil in the oil tank returns and needs to be vented, the air cannot return to the respirator in time, resulting in too high internal pressure of the oil return in the oil tank, the exhaust check valve of the air filter opens, and the oil and gas eject at the same time, resulting in a large loss of oil.

Therefore, the following improvements are made to the respiratory system of the hydraulic station.

① The breathing mode of the system is changed from oil-gas mixing type to oil-gas isolation type. An auxiliary oil tank is added at the upper part of the main oil tank, as shown in Figure B. two rubber breathing airbags are installed in the auxiliary oil tank. The volume of the airbags is calculated as 40L according to the maximum oil consumption of each actuator action. A sliding check valve is installed at the mouth of the airbags. When the turnover of the car dumper is greater than 90 °, it is closed to avoid hydraulic oil overflow when the airbags are damaged. The breathing air bag is communicated with the outside atmosphere through a sliding check valve and a breathing cap. When the hydraulic cylinder retracts, a large amount of oil returns to the oil tank, the pressure in the oil tank increases, the breathing airbag in the auxiliary oil tank exhausts to the atmosphere through the breathing cap, and the airbag shrinks to make room for the returned oil; When the hydraulic cylinder extends, a large amount of oil enters the working chamber of the hydraulic cylinder, a negative pressure is formed in the oil tank, and the external air enters the air bag through the breathing cap. The air bag expands to compensate for the volume loss after the oil in the oil tank is reduced. The oil-gas isolated breathing mode has the following characteristics: A. avoid direct contact and mixing of air and oil; b. It can effectively control the air entering the oil tank. Since the breathing air bag is located in the auxiliary oil tank, the air bag port is tightly connected with the auxiliary oil tank in a plane, which avoids air inlet at the breathing port, and the auxiliary oil tank itself is a closed structure.

② An air inlet and exhaust safety valve is set on the auxiliary oil tank. Add inlet safety valve and exhaust safety valve with appropriate pressure. When the internal pressure of the system is too high and exceeds the set pressure of the exhaust safety valve, the exhaust safety valve acts in time to release the excess pressure in the system and prevent damage to system components due to too high pressure; When the system accidentally runs out of oil, negative pressure will be generated in the system. When the pressure is lower than the set value of the air inlet safety valve, the safety valve will be opened to supplement air to the oil tank to prevent the airbag and auxiliary oil tank from being damaged due to excessive expansion.

The above improvement avoids the mixing of oil and gas, ensures the cleanness of oil, and fundamentally eliminates the problems of unstable action of hydraulic cylinder and oil aging, as well as the simultaneous ejection of oil and gas from the exhaust check valve caused by too high pressure in the oil tank. After improvement, the hydraulic system runs stably.

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