As the energy device of the hydraulic system, the hydraulic pump plays a vital role in the hydraulic system. If the hydraulic pump fails, it will affect the normal operation of the whole hydraulic system. There are two reasons and solutions for insufficient oil supply of excavator hydraulic pump.
1. The air intrudes into the working chamber of the plunger pump, causing the displacement to decrease
1) Ensure that there is no leakage at the connections of all oil inlet pipelines. In order to ensure good sealing, tighten all pipe joints; The plunger pump must have a tight sealing device
2) Avoid flattening and cracking of the oil suction hose. The flow rate of the liquid at the oil suction port shall be controlled as much as possible (for the oil suction hose, the liquid flow rate shall generally not exceed 3-5M / s), so as to prevent the vacuum formed by the pressure at each point of the oil suction pipeline lower than the atmospheric pressure, resulting in flattening, air leakage and air intrusion of the rubber hose
3) Control the oil level height of the oil tank. Generally, the vertical distance between the lowest oil level of the oil tank and the oil suction port shall be less than 0.5m; If the system allows, the oil level in the oil tank shall be higher than the oil suction port of the pump, and the end of the oil return pipe of the hydraulic system shall always be below the oil level, so as to avoid bubbles
4) Regularly check and clean the oil suction filter to prevent the oil suction filter from being blocked, otherwise it creates conditions for the entry of air and may lead to hydraulic air suction
5) If there are a lot of bubbles in the oil tank, it shall be eliminated in time. If there is a considerable amount of air in the oil, loosen the pipe joint at the outlet of the plunger pump to discharge the air in the pump
2. The technical state of the plunger pump itself deteriorates, the structure of the oil suction pipe is unreasonable or the oil quality is poor
1) Optimize the structure of oil suction pipe. The length of oil suction pipe shall be shortened as far as possible, the diameter of oil pipe shall not be too small, and serious bending shall be avoided. Generally, the diameter of oil suction pipe shall be greater than that of oil discharge pipe, because the oil passing capacity of oil suction filter must be greater than the maximum flow of pump.
2) Strictly control the oil pollution and ensure the cleanliness of the hydraulic system. A closed oil tank can be used, and an air filter with certain accuracy shall be installed at the inlet of the oil tank: the new pump and pipeline must be strictly cleaned before use; the oil must be filtered before use to ensure the initial cleanliness of the oil, so as to ensure that the initial oil meets the requirements of the system and components.
3) During operation, it is ideal to control the oil temperature at about 50 ℃, and generally it should be limited to below 80 ℃. In addition to the high ambient temperature and large system pressure loss, the continuous rise of oil temperature is mainly caused by the increase of leakage and the decrease of pump volumetric efficiency, which is bound to lead to insufficient oil discharge.
4) Take measures to ensure that the oil is clean. Pay attention to the following aspects: the steel plate surface in the oil tank shall be treated with oil spray or steel brush for rust removal; When machining hydraulic components, flash and burr shall be removed; If acid pickling is used in the pipeline, it shall be neutralized and washed to ensure the cleanness of the oil, and the oil added to the oil tank shall be precipitated.
5) The viscosity of the selected oil shall be appropriate. If the oil viscosity is too large, the flow resistance in the pipeline will increase, making it difficult for the pump to absorb oil; If the viscosity is too small, the leakage will increase, the lubrication performance will deteriorate, and the wear of moving parts will increase.
