Hydraulic oil pump and Oil motor Difficulties will inevitably occur in the operation link, which can be divided into sudden and abrasive problems. Among them, the problem of abrasiveness mostly occurs at the end of the system operation, mainly due to the natural damage of parts, and the damage to the system is mostly reflected in the ineffectiveness of the sealing materials, the gradual decrease of the movement speed of the actuator and other hazards; However, sudden problems often occur in the early stage of system operation and the middle and late stage of system operation, mainly because managers fail to follow the operation requirements and procedures during operation and maintenance. Most of the damage to the system is reflected in the serious accidents such as burning of oil pump cylinder, creeping of oil motor, damage of hydraulic parts, and rupture of hydraulic pipeline. The frequency of these problems is closely related to the quality of regular operation and maintenance. In order to keep its stable operation state and long service life for a long time, in addition to establishing and improving the necessary regular maintenance mechanism to reduce the wear problems at the end of the period, it should also largely avoid the early and mid late emergencies.
1. Ensure the normal working state of the system hydraulic oil
The problem of hydraulic oil has always been regarded as the culprit of hydraulic equipment failure. In view of the word limit, I will not explain it too much here, but only give some detailed descriptions of some typical problems.
1.1 The viscosity of hydraulic oil shall meet the requirements
For example, ZB type oil pump is recommended to use hydraulic oil whose viscosity changes little with temperature. Its viscosity range is within 20~100cst. When the operating temperature is above 15'C, it is recommended to use 40 # - 2 #, 30 # machine oil and 30 # machine tool hydraulic oil. When the operating temperature is below 25 ° C, it is recommended to use YH-10 aviation hydraulic oil; 20 # machine oil is recommended for domestic a-type and CB-4 type gear pumps and YB type vane pumps.
1.2 Keep the hydraulic oil clean and maintain a constant oil filtering precision
1) The end clearance of the axial piston pump can be self compensated, the clearance is small, the oil film is thin, and the requirements for oil filtering precision of hydraulic oil are extremely high.
2) The oil filtering precision of tilting disc axial piston pump is 10~15 μ m。
3) The destruction of solid impurities, the decrease of capacity and efficiency cause the blocking and jamming of through-hole, variable mechanism, parts, etc.
4) Once the hydraulic oil is polluted, it should be completely replaced and cleaned with clean oil.
1.3 Proper operating temperature
1) - The general operating temperature shall be 10~50C, the extremely high temperature shall be less than 6SC, and the local short-time temperature shall also be less than 90C.
2) Start with light load or no load at low temperature, and resume normal operation after normal temperature-- When the normal intermediate temperature is lower than 10C, it can 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 load can be loaded when the temperature rises above 15'C; Startup is not allowed below - 15C.
3) During operation, it is forbidden to fill cold oil into hot components or hot oil into cold components to prevent excessive temperature difference, rising or collapsing and biting. In winter or severe cold area, if electric heating device is selected to warm the hydraulic oil in the oil tank, since the pump and motor are still cold and easy to get stuck, special attention shall be paid during operation.
2. Ensure normal operating preconditions
2.1 Normal suction conditions
Although all hydraulic oil pumps are positive displacement pumps with a fixed self-priming level, there are many friction sealing surfaces inside the mercury, and the self-priming capacity is limited. Especially, the internal flow channels of the pump are complex. Generally, the oil removal height (from the oil tank to the pump center) is low, about 12~50cm. Some mercury, such as the ZB227 type, is clearly specified that white suction is not allowed, so its suction conditions should be considered, Minimize suction friction resistance:
1) The suction pipe shall not be equipped with a filter, otherwise the negative suction high pressure or auxiliary pump shall be used for oil supply;
2) It is recommended to make the oil tank above the suction port of the pump, or select the auxiliary pump for oil supply. For example, ZB type oil pumps (except ZB227 type) are allowed to self-priming when running below the rated rotation speed (1500r/min), but this will reduce the capacity and number rate by about 5%, and will inevitably interfere with their service life. The manufacturer generally does not recommend this kind of operation method; Most manufacturers recommend that the auxiliary pump be used for oil supply, and the working pressure should be 0.7MPa. When CY type oil mercury operates at the rated rotation speed, it is allowed to self-priming, with the degreasing height ≤ 50mm. When the oil removal pipeline is small, it is allowed to select the flow column height, with the degreasing height of 300-500mm. When the pipeline friction resistance is large, the pump must select auxiliary mercury oil supply, with the oil supply working pressure ≤ 0.4Mpa|
3) The oil suction pipe should be short and straight, and the pipe diameter should be slightly larger than the pump inlet.
4) The suction stop valve shall be fully opened.
Otherwise, cavitation will occur, resulting in reduction of capacity and efficiency, and serious loss of suction control; In addition, the axial piston pump is forced to pull out the plunger from 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 oil drain pipeline are unblocked and generally not connected with back pressure
1) The oil drain pipe of the motor shall be independent of the oil return tank and cannot be connected with the oil return port.
2) The external drain pipe shall 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 when parking, such as making the drain port higher than the housing.
3) - General oil drain port is not connected with back pressure. If back pressure is required, its value shall not exceed 0.16~0.20MPa, or the oil pressure will break the low-pressure seal, such as shaft seal.
2.3 Ensure that Low speed high torque motor Sufficient oil return back pressure
1) Pay special attention to the internal curve type 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, the roller will break away from the stator guide rail surface and cause collision, vibration, noise, and damage in serious cases.
2) The plunger pump, which is also used as an oil motor, should have sufficient oil supply working pressure. For example, when the operating condition of the conveyor limited by the regeneration speed is reduced, the oil drain port is changed into the oil return port of the oil motor.
3. Reasonably assemble
1) The axis and motor shall be elastically connected. The coaxiality deviation of the axis shall not exceed 0.1mm, and the inclination angle shall be ≤ 10 °. Most of the oil pumps and motors run unstably, and the cover is caused by unqualified coaxiality deviation during installation, or the housing working pressure is too large, or the compression force is uneven. Therefore, once the assembly position is adjusted during assembly, it is necessary to install the positioning pin or ground bolt.
2) When the plunger type oil pump is connected to the shaft of the oil motor, the belt pulley and gear cannot be assembled to prevent the excessive radial load from increasing, otherwise additional support will be required.
3) The plastic hose installed between the hydraulic oil pump and the connecting pipe in the hydraulic pipeline for shock isolation shall be free from twisting and a certain amount of slack shall be reserved.
4. Proper application and maintenance
1) The hydraulic oil pump that has been used or disassembled for the first time shall be filled with oil before operation to ensure lubrication.
2) Before operation, the steering gear shall be inspected. It is required that the pump of the steering gear cannot be reversed. When auxiliary mercury oil supply is adopted, the auxiliary pump shall be started first and then the main pump. When parking, 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) Unable to close (close discharge valve) start
4) Do not exceed the maximum operating pressure:
(1) On the nameplate of ZB type hydraulic oil pump, the rated operating pressure (21MPa) and the maximum operating pressure knife (28MPa) are marked.
(2) CY pump only requires rated operating pressure, which is in fact extreme operating pressure.
(3) All specifications Radial hydraulic motor The nameplate is marked with both rated operating pressure and extreme operating pressure.
(4) Generally, the operating pressure is clearly applied according to the working mechanism of extreme operating pressure: the duration of one time of extreme operating pressure is not more than 1min, and the cumulative operating time of extreme operating pressure within 1h is not more than 10%, that is, 6 minutes
(5) The rotation speed shall not exceed the rated value: for example, the maximum rotation speed of the ZB hydraulic oil pump rl=1500 r/min is the allowable rotation speed of the main pump for auxiliary pump mooring or oil motor for Sichuan; Crank connecting rod radial Hydraulic motor Creeping occurs when the rotation speed is less than 10r/min.
(6) It is not suitable to operate at the origin (Q=O) for a long time, otherwise, there will be serious damage to the intercalation, cooling and sealing due to no oil leakage.
(7) During disassembly and inspection, it is necessary to prevent the valve blocks from being misallocated, and to avoid excessive hammering and prying (the parts have high strength and have been prepared). Before installation, the parts should be cleaned and dried with volatile detergent, and cotton textile cleaning is prohibited.
