At present, China’s mining hoist braking device mostly uses a hydraulic disc brake device. This device consists of a hydraulic station, a disc brake, and an electronic control system. The hydraulic power unit with a gear pump drives the dynamic system and regulates the pressure mechanism. The stable and reliable operation of this hydraulic power unit is essential for mine safety lifting. Its performance and quality directly affect both equipment and personnel safety. The use of the hydraulic station demonstrates constant deceleration control. During emergency braking, it adjusts the average braking torque according to load changes. This capability achieves constant deceleration control and meets the hoisting system’s requirements for constant deceleration. However, the hydraulic braking system and control system are more complex. Improper use and maintenance can lead to issues such as excessive braking deceleration and insufficient braking torque. These failures can result in serious consequences.
The role of the hydraulic power unit with gear pump of the hoist
The hydraulic power unit with a gear pump in the hoist provides pressure oil at different values. This oil helps achieve various braking torques. Additionally, the unit serves as a disc brake. Under accident conditions, the system can make the brake oil pressure drop rapidly to a pre-set value. After a delay time, the brake oil pressure will return to zero quickly. This process ensures that the brake reaches a full braking condition. Supply the pressure oil needed for the rope adjusting device of single rope double drum hoist.
Elevator hydraulic power unit with gear pump common failure analysis and treatment methods
Oil leakage and oil pressure instability After long-term use, the safety brake device may experience leaks. These leaks can occur between various oil collection points. It can also leak between the valve and the oil collection. These leaks can lead to oil pressure drops and cause the valve to loosen. The cause is usually loose screws, which we can tighten to resolve the issue. Oil pressure instability may result from air mixing in the hydraulic system, so we should remove the air. Additionally, if the electro-hydraulic pressure regulator coil has poor filtering and causes up-and-down vibrations, adding electrolytic capacitors to enhance the filter can help stabilize the oil pressure.
Oil pressure value can not be guaranteed Because there is air intake in the system, the oil in the tank has a lot of foam, or relief valve, electromagnetic reversing valve leakage, treatment: check the oil pump suction port leakage; oil pump suction pipe joints at the tightening of oil suction; suction filter screws are tightened; check the suction filter to the oil pump suction port in the pipeline is not leakage; check whether the oil pump end cap screws are tightened; clean the relief valve! Valve spool, if the spool in the valve body activities are not flexible, you can hold the spool in the body back and forth grinding; cleaning solenoid valve spool, the requirements of the spool in the body of the valve movement is flexible to ensure that the work of the spool in place.
Zero oil pressure brake does not release the brake system does not have the pressure of the reason: the oil pump rotation direction is reversed or the oil pump does not have the output fluid; electro-hydraulic proportional device on the relief valve spool jammed, blocked damping holes; oil pump suction port is not smooth, suction filter clogging; pressure valve dirt, cone valve can not be closed. Treatment: To rule out oil pump failure, correct the pump’s direction of rotation. Disassemble the relief valve and clean it, ensuring the spool moves flexibly within the valve body, and blow through the damping holes with compressed air. Clean the filter cartridge and check the suction pipeline for clogs. Dismantle the pressure valve and remove the cone valve core for cleaning.
Residual pressure is too large Residual pressure is too large to make the brake lose its effect, the main reason is: electro-hydraulic pressure regulating device on the control lever gear plate from the nozzle distance is too small; relief valve throttle hole is too large. Treatment: adjust or replace the gear plate on the control lever; replace the throttle hole of the relief valve with a smaller diameter throttle hole.
Failure of secondary brake oil pressure holding performance Produce secondary brake oil pressure value pressure failure reasons are: oil block on the big relief valve dirt stuck so that the spool shut off; one-way throttle valve opening is too large, a large amount of oil leakage; solenoid reversing valve dirt, internal leakage is too large. For this type of failure can first remove the valve core cleaning, remove the dirt, so that the valve core in place, and then adjust the one-way throttle shut-off valve, so that the opening as small as possible, to play the role of throttling and replenishment of oil.
Hydraulic power unit with gear pump should pay attention to the use of the process
During the processing, transport, and installation of the hydraulic power unit with gear pump components and pipelines, various debris like iron filings, abrasives, and dust may enter the system. To prevent this, we must thoroughly clean all the valves, tubes, and tanks before using the hydraulic station for the first time. The tubes should be cleaned using the pickling method. During the working process, we should frequently check the wear and tear of various valves, pumps and other components, and regularly replace the seals, which should not have burrs or flying edges. Oil temperature should be controlled within 65 ℃. Regularly replace the oil in the hydraulic power unit with a gear pump. If you notice a large number of bubbles on the oil surface or the oil appears very dirty during use, replace it immediately.
Additionally, choose the viscosity of the hydraulic oil based on actual needs, ensuring it is neither too high nor too low. Viscosity is too large, internal friction resistance, mobility is small, poor heat dissipation, start-up difficulties, power consumption, but also accelerate wear and tear, easy to cause system heating; viscosity is too small, leakage will occur and reduce the working pressure.In practice, you should select the appropriate viscosity of the oil based on the type of oil pump you choose. Follow the recommended viscosity of hydraulic oil for the oil pump.
The presence of air in the hydraulic system will affect the normal operation of the system. Air should not be present in the oil pipe and brake cylinder connected from the hydraulic station to the disc brake. When filling the brake cylinder with oil for the first time after installation, the oil pressure should not be too high. Before filling the oil, ensure that the exhaust screws on all cylinders are ready for operation for a certain period of time. A small amount of air may intrude, so if you notice that the brake takes a long time to release, exhaust the system. Hydraulic station all stop working, and then restart work, should first open the oil pump motor, and then make the safety.
Energize the valve solenoid; otherwise, the system will force air into the cylinder.
How to deal with high-frequency oscillations generated by system pressure
Because the high-pressure device in the hydraulic system is a flexible component, in which the cross spring, relief valve in the small spring, have their own self-oscillation frequency, when the oil pump oil pressure pulsation frequency (independent of the power supply voltage) and other self-oscillation frequency is equal or similar, then it will produce high-frequency oscillation.
Due to the uneven air gap within the magnet, the force on the moving coil and control lever is unbalanced. Under the action of the pulsating oil pressure from the oil pump, high-frequency oscillations may occur.
Treatment: A. Adjust the current, strengthen the filter, so that it is stable in the required range. B. Adjust the magnet gap to make it even. C. The cross spring to be fixed. D. Proportional regulator to check the proportional valve whether there is air, if necessary, open the open air screw plug bleed.
What if the current in the T-coil rises but the pressure following is slow
Mainly KT coil by external forces into an ellipse, up and down is not free, such as can be repaired that can be used, such as repair is not good, can only replace the new KT coil. One side of the control rod touches a small hole in the middle of the cross spring. This contact causes friction up and down, creating resistance and affecting the followability. To fix this, loosen the cross spring nut to adjust the position of the control rod and the small hole. Ensure that the control rod is centered in the small hole.
Electro-hydraulic regulator type hydraulic station main pressure is not on pressure how to do
Clean all the small holes in the electro-hydraulic pressure regulator with paraffin or petrol, and clean all the guides and valve bodies of the relief valve. This allows us to pressurize it. If the nozzle, control rod end surface is not flat also affects the upper pressure. Screw an M12 standard ring gauge onto the nozzle, and ensure the end face slightly protrudes above the plane of the ring gauge. Then, smooth the end face with a fine oil stone. Find the correct alignment of the end face of the control rod on the lathe using a percentage table. Ensure that the original end face is perpendicular to the shaft. Then, use the lathe to repair the end face.
How to deal with unstable and fluctuating system pressure
Air has mixed into the system. To resolve this, open the disc brake bleeder valve, release the air, and then tighten the valve to restore normal operation. Air mixes with the oil in the tank, creating many bubbles. The system can only operate normally after allowing the oil to stand until the bubbles disappear.
Failure to tighten the oil pump end cap allows air to enter the system. Additionally, if the pipe fitting on the pipe is not tightened, it can also let air into the system. As a result, the system’s oil pressure becomes unstable. As long as the oil pump pipe seal is intact, tighten the pump end cap screws or pipe fitting nuts. The oil pump should ensure a certain clearance between the oil pump rotor and the oil distribution disc. This clearance is necessary to prevent the rotor from wearing out the distribution disc. This clearance prevents the rotor from wearing out on the disc.
It is also possible that the KT coil through the signal current filtering is not good, with AC components, causing pressure fluctuations, increase the capacitance, strengthen the filter so that the signal current does not have AC components can be.
What are the most important factors to ensure the proper functioning of a hydraulic power unit with gear pump?
All pipes undergo pickling and neutralization with lime water. We ensure that we no longer weld the treated pipes. Additionally, we prevent the PTFE raw material tape used at the joint threads from being screwed into the piping.
Clean the inside of the tank with paraffin. Then use flour to make a dough and stick it to the dirt to remove it from the tank.
Filter the oil with a 20μm filter before adding it to the tank. Avoid adding the oil directly to the tank.
Regularly change the hydraulic oil, and test the incoming oil before replacing it.
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