Hydraulic oil pump and Oil motor There will be more or less failures in use, which can be divided into sudden and abrasive problems. Among them, the abrasion problem often occurs at the end of the system work, which may be caused by the natural destruction of components. The destruction of the system is mostly reflected in the failure of seals, the gradual reduction of the movement speed of the actuator and other small effects; However, sudden problems often occur in the early stage of system operation and the middle stage of system work, which may be caused by the manager's failure to follow the operating standards and specifications when using and maintaining the system. Most of the damage to the system is reflected in vicious accidents such as burning of oil pump cylinder, creeping of oil motor, damage of hydraulic parts, cracking of hydraulic pipes, etc., which are extremely harmful. The frequency of such equipment failures is closely related to the quality of daily operation, maintenance and repair. In order to keep its long-term good operation status and relatively long service life, in addition to establishing and improving the necessary daily maintenance mechanism, so as to reduce the subsequent wear problems, it should also be more effective to avoid early and medium-term emergencies.
1. Ensure the stable state of the system hydraulic oil
The problem of hydraulic oil has always been regarded as the originator of the abnormality of hydraulic system. In view of space limitations, I will not say more here, but only give a detailed description of some typical cases.
1.1 The viscosity of hydraulic oil shall meet the requirements
For example, ZB oil pump is recommended to use hydraulic oil whose viscosity changes very little with temperature. Its viscosity range is within 20~100cst. When the ambient temperature is above 15C, it is recommended to use thickened 40-2 and 30 machine oil and 30 machine tool hydraulic oil. When the ambient temperature is below 25 "C, it is recommended to use YH-10 aviation hydraulic oil; 20 machine oil is strongly recommended for domestic a and CB-4 gear pumps and YB vane pumps.
1.2 Ensure that the hydraulic oil is clean and maintain the corresponding oil filtering accuracy
1) The end clearance of the axial piston pump can be automatically compensated, the clearance is small, the oil film is thin, and the filtering accuracy of the hydraulic oil is high.
2) The oil filtering accuracy of tilting disc axial piston pump is 10~15 μ m。
3) Solid impurities lead to destruction, and volume efficiency decreases, resulting in blocking and blocking of through-hole, variable mechanism, parts, etc.
4) Once the hydraulic oil is polluted, it should be completely replaced and cleaned with cleaning oil.
1.3 Moderate operating temperature
1) - The general operating temperature should be 10~50 "C, the higher temperature should be less than 65" C, and some short-term temperatures should also be less than 90 "C.
2) Light load or no-load operation shall be carried out at low temperature, and normal operation shall be resumed after the temperature is normal-- Generally, when the temperature is less than 10C, it can only be loaded after no-load operation for more than 20min: if the temperature is below 0 ° C or above 35C, it should be heated or cooled; During regional or winter startup, the temperature should rise above 15 'C before loading; Cannot run below - 15C.
3) During operation, it is forbidden to fill cold oil into hot elements or hot oil into cold elements to avoid excessive temperature difference, differential expansion or contraction and seizure. In winter or
In severe cold areas, if electric heating device is used to heat the hydraulic oil in the oil tank, the pump and motor are still frozen and easy to get stuck, so special attention should be paid during operation.
2. Ensure normal working environment
2.1 Suction standard under normal condition
Although all hydraulic oil pumps are positive displacement pumps with certain self-priming capacity, there are many internal friction sealing surfaces in mercury and the self-priming level is limited, especially the internal structure of the pump through the flow passage
Miscellaneous. Generally, the oil absorption height (from the oil level of the oil tank to the pump core) is relatively low, about 12~50cm. Some mercury is explicitly required not to be sucked in white, such as ZB227,
Therefore, it is necessary to consider the suction standard and minimize the suction friction resistance:
1) The suction pipe shall not be equipped with a filter device, otherwise negative suction or auxiliary pump shall be used for oil supply;
2) Try to make the oil tank above the pump suction inlet, or use the auxiliary pump to supply oil. For example, ZB oil pumps (except ZB227) are allowed to self-priming when running at rated speed (| 500r/mim), but this often results in a reduction of capacity and number rate of about 5%, which will inevitably affect the service life. The manufacturer generally does not recommend this kind of operation method; Most manufacturers recommend that the auxiliary pump should be used for oil supply, with a constant pressure of about 0.7MPa. When CY type oil mercury operates at rated speed, the allowable self-priming oil suction height is ≤ 500mm. When the oil suction pipeline is small, the allowable self-priming oil suction height is 300-500mm. When the pipeline resistance is large, the pump must use auxiliary mercury oil supply, and the oil supply pressure is ≤ 0.4Mpa|
3) The oil suction pipe shall be short and straight, and the pipe diameter shall be slightly larger than the pump inlet.
4) The suction stop valve shall be opened. Otherwise, cavitation will occur, which will reduce the capacity and efficiency and seriously lead to loss of suction control; In addition, the axial piston pump is forced to pull the plunger out of the cylinder by the ball joint during the suction stroke, which is easy to damage the ring joint.
2.2 Ensure that the oil pump and oil motor drain lines are smooth, and generally do not connect back pressure
1) The oil drain pipe of the motor shall return to the oil tank alone, and shall not be connected with the oil return port.
2) The external drain pipe must ensure that the housing of the parking pump and oil motor is filled with hydraulic oil to prevent the hydraulic oil in the housing from returning to the oil tank after shutdown, such as making the drain port higher than the housing.
3) Generally, the oil drain port is not connected with back pressure. If back pressure is required, the value cannot exceed 0.16-0.20MPa, otherwise the oil pressure will break through the low-pressure seal, such as shaft seal.
2.3 Guarantee Low speed high torque motor Sufficient oil return back pressure
1) Pay special attention to the internal curve oil motor. Generally, the oil return back pressure should be 0.3~1.0MPa. The higher the rotation speed is, the greater the oil return back pressure should be. Otherwise, rolling will occur
The wheel breaks away from the curved surface of the stator guide rail, resulting in collision, vibration and noise, which may lead to damage in serious cases.
2) The plunger pump used as an oil motor shall have sufficient oil supply pressure. If the oil drain port becomes an oil motor when the regenerative speed limited winch is in reduced working condition
The return port of the.
3. Proper assembly
1) Shaft - It shall be elastically connected with the motor, and the axis coaxiality deviation shall not exceed 0.1mm, and the inclination angle shall be ≤ 10 °. Most hydraulic oil pumps and Oil pressure motor The rotation is unstable, the coaxiality deviation of the cover is unqualified during assembly, or the housing pressure is too large, or the compression force is uneven. Therefore, if the installation method is adjusted properly during installation, the positioning pin or ground bolt should be installed.
2) When the plunger type hydraulic oil pump is connected to the shaft of the oil pressure motor, the pulley and gear cannot be assembled to prevent additional radial load, or support must be attached.
3) The hose installed between the hydraulic oil pump and the connecting pipe of the pressure oil pipeline for shock isolation shall not rotate, and corresponding slack shall be reserved.
4. Standard use and maintenance
1) The hydraulic oil pump produced or disassembled for the first time shall be filled with oil before starting to ensure lubrication.
2) Before starting, the deviation shall be checked, and the deviation pump shall not be reversed. When auxiliary oil supply is adopted, the auxiliary pump shall be started first and then the main pump. When stopping, the main pump shall be stopped first and then the auxiliary pump shall be stopped to ensure that there is oil in the pump.
3) It cannot be fully closed (close the discharge valve) to start.
4) Do not exceed the pressure of larger work:
(1) On the nameplate of ZB hydraulic oil pump: not only the standard pressure (21MPa), but also the working pressure knife (28MPa) of FJ is marked.
(2) CY type pump only requires standard pressure, which is in fact higher pressure.
(3) All models Radial hydraulic motor The label is marked with both standard pressure and high working pressure.
(4) Generally, the working pressure shall be selected according to the working system of higher pressure: the duration of one continuous T operation of higher pressure shall not exceed 1min, and the cumulative operating time of higher pressure within 1h shall not exceed 10%, that is, 6min
(5) The rated speed shall not be exceeded: for example, the larger speed rl=1500r/min of ZB hydraulic oil pump is the allowable speed of the main pump for auxiliary pump mooring or the oil pressure motor; Crank connecting rod radial Hydraulic motor Creeping will occur when the speed is less than 10r/min.
(6) It is not suitable to operate at zero position (Q-O) for a long time, or there may be no oil discharge, which will lead to the deterioration of smell, lubrication, cooling and sealing.
(7) During maintenance, it is necessary to prevent the mismatch of each coupling part, and prevent the parts from being hammered and pried with force (the parts have high hardness and have been researched and adjusted). The parts should be cleaned and dried with volatile detergent before assembly, and it is forbidden to use cotton textile for cleaning.
