The hydraulic pump station is the power component of the hydraulic system, which is driven by the engine or the motor, inhales oil from the hydraulic tank, forms a pressure oil discharge, and sends it to the actuator. Hydraulic pump station is divided into gear pump, plunger pump, vane pump and screw pump according to structure.
hydraulic pump station failure do not know where to start? Just look at this!
One of the problems often encountered in the maintenance of hydraulic pump stations is that the pressure of the hydraulic system is abnormal, and the pressure does not go up or down.
Pressure is one of the two most basic parameters of hydraulic system, which determines the performance of hydraulic system to a large extent. This failure is manifested as: when the pressure adjustment of the hydraulic system is performed, the adjustment failure of the system pressure can not be established, the pressure is insufficient,or there is no pressure at all, or the pressure can not be adjusted down, or it falls down after rising, and the adjusted pressure is unstable and the pressure fluctuations are large.
1. Causes of stress disorders
① hydraulic pump station caused by no flow output or output flow is not enough:
A hydraulic pump station steering wrong, there is no pressure oil output, the system pressure does not go up at all;
B Because the motor speed is too low, the power is insufficient, or the hydraulic pump station has been used for a long time, the internal wear is inside, the leakage is large, and the volume efficiency is low, resulting in insufficient output flow of the hydraulic pump station and insufficient system pressure.
②The inlet and outlet of the hydraulic pump station are reversed, and the pump is a non-reversible pump, which can not only fill the oil, but also destroy the oil seal of thepump shaft.
D Other reasons, such as the pump suction pipe is too small, the suction pipe seal is poor and air leakage, the oil viscosity is too high, the oil filter is blocked by impurities and dirt, resulting in large pump suction resistance and suction phenomenon, so that the output flow of the pump is not enough, the system pressure does not go up.
Pressure regulating valve such as relief valve is faulty.
③For example, the spool of the relief valve is stuck in the large opening position, and the pressure oil output from the hydraulic pump station flows back to the tank through the relief valve, that is, the pressure oil is short-connected with the return oil circuit; It may also be that the damping hole of the pressure control valve is blocked, or the pressure regulator spring is broken and other reasons cause the system to have no pressure. On the contrary, when the spool of the relief valve is stuck in the position of the closing valve port, the system pressure does not come. In the working process, it is found that the pressure does not rise or the pressure does not come, it is likely that the reversing valve fails, resulting in the system unloading or closing; Or due to serious internal leakage between the spool and the valve body hole.
④ The unloading valve is stuck in the unloading position, the system is always unloading, and the pressure does not go up.
⑤ Internal and external leakage of the system.
⑥ There is a position in the valve mounting plate (integrated block) where the pressure oil channel is in collusion with the oil return channel.
⑦The spool of the reversing valve is not reversed in place, resulting in the channeling of the pressure oil chamber and the return oil chamber.
⑧ The locking nut connected with the hydraulic cylinder piston and the piston rod is loose, and the piston runs out from the piston rod, so that the two cavities of the hydraulic cylinder are interconnected.
2. The influence of stress disorder
① The actuator (such as hydraulic cylinder, hydraulic motor) does not move or although it moves, the load stops or is weak, and the load cannot be overcome and the work is done;
②The hydraulic system cannot achieve the correct working cycle, especially in the sequential action circuit of pressure control
③ Some valves that rely on pressure control can not work, such as hydraulic direction reversal valves, hydraulic control check valves, cartridge valves, pressure relays, etc., which also lead to hydraulic pressure
The system is not working properly:
④ The speed of the actuator is not enough because the load flow rate is not enough, so that the movement speed is reduced
⑤Failure caused by uncontrolled pressure regulation, including safety accidents,
3, the elimination of pressure disorders
① Replace the motor wiring, correct the rotation direction of the hydraulic pump station, and replace the motor with the matching power.
② Correct the direction of the inlet and outlet of the hydraulic pump station, especially for non-reversible pumps.
③ Appropriate coarse pump suction pipe size, suction pipe joint to strengthen the seal, clean the oil filter, etc
④ Remove the fault of the direction valve. If the unloading valve is equipped, remove the fault of the unloading valve.
⑤ Identify the specific location of internal leakage and external leakage, and eliminate internal and external leakage faults
⑥ Check the hydraulic cylinder;
hydraulic pump station failure do not know where to start? Just look at this!
hydraulic pump station maintenance often encountered two problems, hydraulic pump station, hydraulic system leakage:
1. Classification of leakage
There are two kinds of leakage: internal leakage and external leakage. According to the degree of leakage, there are many forms of oil film scraping, leakage, drip and spray leakage. Oil film scraping occurs between relative moving parts, such as the sliding pair of the rotary body, reciprocating movement (such as the piston rod of the hydraulic cylinder, the spool extension part of the manual reversing valve, etc.); Leakage occurs in the joint of the end cap valve plate. Dripping occurs in pipe joints and other places; Leakage occurs in the pipe rupture leakage sealing and so on.
2. The harm of oil leakage
External leakage causes work environment pollution waste resources, internal leakage causes temperature rise, efficiency decline, work pressure can not go up,system weakness, slow down the movement speed and other failures.
3. Causes of oil leakage
(1) The seal quality is not good, the assembly is not correct and damaged, the use of long aging deterioration, and the working medium is incompatible with the source caused by the seal failure;
(2) The wear of the relative moving pair causes the matching gap to increase, the internal leakage to increase, or the matching surface is strained and the internal and external leakage is generated;
(3) the oil temperature is too high;
(4) The system use pressure is too high;
(5) The size of the sealing part is not correctly designed, the processing accuracy is poor, and the assembly is not good to produce internal and external leakage.
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