When the rotor of the vane pump rotates, under the action of centrifugal force and pressure oil, the tip of the vane is tightly attached to the inner surface of the stator. In this way, the working volume formed by the inner surfaces of the two blades, the rotor and the stator, first sucks oil from small to large, and then discharges oil from large to small. When the blades rotate for one revolution, oil absorption and oil discharge are completed twice.
1. Working principle of single-acting vane pump
The pump is composed of rotor 1, stator 2, blades 3, oil distribution plate and end cover.
The inner surface of the stator is a cylindrical hole. There is an eccentricity between the rotor and the stator. The blades can slide flexibly in the slots of the rotor. Under the action of the centrifugal force when the rotor rotates and the pressure oil at the root of the blade, the top of the blade is attached to the inner surface of the stator, so two adjacent blades, the oil distribution plate, the stator and the rotor Formed a sealed working cavity in between. When the rotor rotates in a counterclockwise direction, the blades on the right side of the figure extend outward, the volume of the sealed working chamber gradually increases, and a vacuum is generated, so the oil is sucked in through the oil suction port 6 and the upper window of the oil distribution plate 5. And on the left side of the picture. The blades are retracted inward, the volume of the sealed cavity is gradually reduced, and the oil in the sealed cavity is pressed out through another window of the oil distribution plate and the oil pressure port 1 to be output to the system. This kind of pump sucks oil and pressurizes oil once during the process of one revolution of the rotor, so it is called single-acting pump. The rotor is subjected to radial hydraulic unbalanced force, so it is also called unbalanced pump, and its bearing load is relatively large. The displacement of the pump can be changed by changing the eccentricity between the stator and the rotor, so this type of pump is a variable pump.
Second, the working principle of the double-acting vane pump
Its principle of action is similar to that of a single-acting vane pump. The difference is that the stator surface is composed of eight parts with two long radius arcs, two short radius arcs and four transition curves, and the stator and rotor are concentric. . In the case that the rotor rotates clockwise in the figure, the volume of the sealed working chamber gradually increases at the upper left and lower right corners, which is the oil suction area, and gradually decreases at the lower left and upper right corners, which is the oil pressure area; the oil suction area There is a section of oil sealing area between the oil pressure area and the oil pressure area to separate them. Each time the rotor of this pump rotates, each sealed working chamber completes oil suction and oil pressure twice, so it is called a double-acting vane pump. The two suction zones and two pressure zones of the pump are radially symmetrical, and the hydraulic pressure acting on the rotor is radially balanced, so it is also called a balanced vane pump.
The instantaneous flow of the double-acting vane pump is pulsating, and the pulsation rate is small when the number of vanes is a multiple of 4. For this reason, the number of blades of a double-acting vane pump is generally 12 or 16.
Three, matters needing attention
In addition to preventing dry rotation and overload, preventing air suction and excessive suction vacuum, the management points of vane pumps should also be noted:
1. If the pump steering changes, the suction and discharge direction will also change. The vane pump has a prescribed steering, and the reverse is not allowed. Because the rotor blade groove is inclined, the blade is chamfered, the bottom of the blade is connected to the oil discharge cavity, and the throttle groove and suction and discharge ports on the oil distribution plate are designed according to the established steering. Reversible vane pumps must be specially designed.
2. The vane pump assembly oil distribution plate and stator are correctly positioned with positioning pins. The vanes, rotor, and oil distribution plate must not be installed in reverse. The suction area on the inner surface of the stator is most easily worn. If necessary, it can be turned over and installed to change the original suction area. Continue to use for the discharge zone.
3. Disassembly and assembly Pay attention to the clean working surface, and the oil should be well filtered during work.
4. If the gap of the blade in the blade groove is too large, the leakage will increase, and if it is too small, the blade cannot expand and contract freely, which will cause malfunction.
5. The axial clearance of the vane pump has a great influence on ηv.
1) Small pump -0.015～0.03mm
2) Medium-sized pump-0.02～0.045mm
6. The temperature and viscosity of the oil should generally not exceed 55°C, and the viscosity should be between 17 and 37 mm2/s. If the viscosity is too large, it will be difficult to absorb oil; if the viscosity is too small, the leakage will be serious.
As a pump product, the vane pump refers more to the sliding vane pump. As long as you are interested in searching on Baidu, vane pumps almost all refer to sliding vane pumps.
4 Frequently Asked Questions
What are the common faults and troubleshooting methods of vane pumps?
(1) Insufficient flow. The reasons for the insufficient flow of the vane pump and the troubleshooting methods are shown in Table 1-6.
Table 1-6 Causes of insufficient flow of vane pumps and troubleshooting methods
Common faults and their causes
Method of exclusion
The screws at the top cover are loose, the axial clearance increases, and the volumetric efficiency decreases
Tighten the screws properly to ensure the gap is uniform and appropriate (the gap is 0.04～0.07 mm)
The sliding of individual blades is not flexible
Clean. If it is still inflexible after cleaning, it should be deployed in a single slot to make the blades
The inner surface of the stator is worn, and the blades cannot make good contact with the inner surface of the stator
Wear of the inner surface of the stator is generally at the oil suction cavity
Severe wear on the end face of the valve plate
replace
Blades and rotors are reversed
Make the blade pitch direction consistent with the rotation direction of the rotor
Large system leakage
Check for leaks one by one, and check whether the pressure gauge is blocked by dirt
(2) The oil cannot be sucked up. See Table 1-7 for the reasons and troubleshooting methods of vane pump oil failure.
Table 1-7 Causes and troubleshooting methods of vane pump oil failure
Common faults and their causes
Method of exclusion
The oil level is too low and the oil cannot be sucked up
Check and fill to the specified oil mark line
The oil viscosity is too large, so that the blades will not slide in the rotor groove.
flexible
Generally use 20# hydraulic oil or 22# turbine oil
The end face of the oil distribution plate is in poor contact with the inner plane of the shell, and the high and low pressure chambers are in collusion
Refurbish the end face of the oil pan
There are blisters inside the pump body, and the high and low pressure chambers are in collusion
replace
The electric motor turns in the wrong direction
correct
(3) The noise of the pump is too loud. The reasons for the excessive noise of the pump and the elimination methods are shown in Table 1-8.
Table 1-8 Reasons for excessive noise of the pump and troubleshooting methods
Common faults and their causes
Method of exclusion
The oil filter is clogged and the oil is not sucked smoothly
Wash
Air leakage at the suction side
Use butter to check the joints of the oil suction pipe one by one. If the noise is reduced, the joints should be tightened. Or directly observe whether air bubbles appear at the oil return port.
Pump end seal wear
Grease the oil seal at the shaft end, if the noise is reduced, replace the oil seal
Pump cover screws are loose due to vibration
Apply butter to the screw connection, if the noise is low, tighten the screw
Pump and motor shafts are not concentric
Readjust to make it concentric
The two sides of the blade groove of the rotor are not perpendicular to the two ends
Replace the rotor
The unloading triangle groove of the oil distribution pan is too short
Use assorted files to modify appropriately, so that when the previous blade passes through the unloading groove, the latter blade has been separated from the oil suction cavity
The seal at the shaft end of the spline groove is too tight (hands are hot)
Adjust and replace appropriately
The pump speed is too high
Use according to the specified speed
Insufficient oil suction of oil pump
Check the oil level
Serious hydraulic oil pollution
Remove the oil filter, check whether the oil filter is damaged, whether there is more solid adsorption, replace the oil filter and hydraulic oil
Pressure runout
Check the wear of the pump core total pressure valve spool
