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What are the common faults of vane pump?

Update:20-12-2019
Summary:

1、 Determination of common faults of vane pump: 1. Grin […]

1、 Determination of common faults of vane pump:
1. Grinding pump (burning plate): cause: the oil is too dirty, improper installation, water enters the oil, and there are iron chips in the oil (new machine market occurs).
2. High oil temperature or insufficient parts manufacturing accuracy.
3. High noise of vane pump: especially large
a. Air leaks at the oil inlet. (O-ring seal failure, screw too long or flange too thin)
b. The filter is blocked and the oil flow is insufficient.
c. The viscosity of the oil is too high. (too cold or wrong brand)
d. Assembly error. (when changing the direction and position of the inlet and outlet, the method and essentials are improper, or the sealing ring is not installed properly, and the pump core positioning pin is not inserted into the air of the back cover, etc.).
When it is relatively large
a. The above situation is even.
b. The product quality is not good.
3. No pressure in the system:
a. Overflow valve fails. (to be cleaned or replaced)
b. Pressure reducing valve fails. (to be cleaned or replaced)
4. When the internal curve of the stator is in the form of washboard ripple: it is caused by poor oil absorption. The phenomenon is that the pressure is unstable, the pressure is too low, the noise is too high, there is obvious metal knocking sound, and the crackling sound caused by compressed air intake. The reasons are as follows:
a. The oil is too viscous and the oil absorption is insufficient.
b. The oil suction filter is blocked or too small, and the oil suction area is not enough.
c. The oil level is too low and the oil is not in place.
4. If the pressure of the system exceeds the rated standard, the following conditions will occur:
a. The housing is broken.
b. The stator is broken.
c. Shaft fracture.
d. Broken screw.
e. Shorter life.
Cause: the oil in the tank is too dirty or the overflow valve and other functional valves are stuck after entering the scrap iron. It will lead to infinite pressure rise. If the "safety protection" design of the system is unreasonable or the "safety factor" is too low, the instantaneous pressure will also exceed the standard. When the system pressure exceeds the rated standard, the internal parts of the pump core can not bear the high pressure, resulting in the fracture of a part or the rapid shortening of the service life.
Check the pressure: connect the pressure gauge at the oil inlet and outlet of the oil pump, and observe the pressure under normal working conditions.

2、 Improper use of vane pump:
1. Incorrect installation method:
a. Too tight coupling: due to the small or no clearance between the coupling and the shaft, the bearing will be injured when it is knocked hard, leading to early damage of the bearing and affecting the life of the whole pump core.
b. Axial force on shaft head: since there is no certain axial clearance when installing the coupling, the hardware installation will damage the bearing and the bearing retainer ring, and even the whole pump core.
c. Coaxiality out of tolerance: if the coaxiality exceeds the specified value during installation, the bearing and the whole pump core will be eccentric and early damaged. Generally, it is better to control the coaxiality ≤ 0.1mm.
2. Poor system environment:
a. Oil is too dirty: because the mailbox is not sealed, the surrounding dust and iron mixed into the oil can cause early damage to the oil pump.
b. Temperature is too high: since no cooling device is installed, the oil temperature will continue to rise during continuous use of the machine. If the oil temperature is over 70 ℃ for a long time, the service life of the oil pump will be greatly shortened, and generally it will be damaged (sometimes shorter) in half a year to a year.
c. Water in the oil: in the water cooling device, due to the poor sealing of the water pipe, the water enters the oil, which causes the rust, locking and the blade can not be thrown out of the pump core parts.
3. Error when rotating port direction:
a. The pump core Xiao Zi did not go into the Xiao hole (or was pulled out during rotation), which was caused by the reduction of the oil suction port space of the oil pump, the oil suction was blocked and the oil suction was not smooth, which was shown as: the noise was very large, the pressure swung, the long-term use would make the oil temperature rise too fast, and the life of the stator after the internal curve impact into a corrugated shape would be shortened.
b. Oil leakage occurs when the sealing ring is cut or the screw is tightened unevenly during rotation.
3、 Technical identification after serious damage of oil pump: after the damage of oil pump, first check the appearance, internal and relevant phenomena. When the following phenomena occur, the corresponding causes can be determined:
1. Bearing damage: when the pump core is seriously damaged and more damage occurs, any bearing damage shall be deemed as improper installation. (because the bearing is damaged first, and when the bearing is damaged, the shaft will swing, which tells that the swing will not cause damage to other parts.)
2. Embroidered inner liner: when the pump core is seriously damaged by many damages, as long as there is rust. It is always considered as the result of water entering the oil. (because when the oil is normal, there will never be rust)
3. Poor oil quality: when the pump core is seriously damaged. As long as there are dirt, foreign matters in the oil or the oil has turned black, it shall be regarded as the result of dirty oil and poor oil quality.
4. New shaft fracture: try to check the fracture position. If the material or heat treatment is not good, its damage point should be the weakest link, i.e. the place with the smallest diameter or the place with the knuckles. If the fracture is not at the weakest place, it should be considered as improper installation and the coaxiality deviation is too large.
5. In the inspection of materials, the composition, metallographic structure, hardness, etc. of materials shall be inspected, and the sequence and causal relationship of damaged parts shall be analyzed to find out the cause finally.
4、 The following are quality problems in the manufacture of vane pump products:
1. High noise: as long as other reasons are eliminated, it should be a quality problem.
2. Part scratch: it is relative to the scratch of the side plate after turning. The phenomenon of diagonal scratch should be a quality problem.
3. Shaft fracture: when the fracture is at the weakest place and other parts are in good condition, it is the quality problem of the shaft.
4. Rotor fracture: other parts are not broken, only the rotor is broken, which is a quality problem.
5. Blade fracture: no other parts are broken, only blade fragments, it is a quality problem.

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