Railway engineering equipment_ Hydraulic switch oil circuit fault
Railway engineering equipment_ Hydraulic switch oil circuit fault
With the increase of running speed and rail type, the switching force of turnout increases. In order to meet this requirement, ZY series switch machines have been replaced in a certain section since 1990, and now there are 264 sets. ZY series electro-hydraulic switch machine adopts closed oil circuit internal locking structure, which cancels ZD6 series gear strip, extrusion pin, reducer and other parts, and has reliable conversion force and close bonding effect. In more than ten years of use, many parts have failed in varying degrees due to the aging and wear of seals. In recent years, most of the fault parts of the hydraulic switch machine in use are concentrated in the oil circuit system, which directly affects the operation quality of the turnout.
The electro-hydraulic switch machine is mainly composed of hydraulic station (power mechanism), switch machine and SH type conversion lock. The common electro-hydraulic switch oil circuit system adopts closed oil circuit, as shown in Figure H (taking ZY4 as an example). As can be seen from figure h, the oil circuit system is mainly composed of oil tank, (main and auxiliary), manual short-circuit valve, oil circuit flow regulating valve, starting hydraulic cylinder and other parts, which are connected by many connecting pipe fittings. The working process is as follows. The motor rotates counterclockwise with the hydraulic pump.
The pump sucks oil from the right cavity of the hydraulic cylinder and auxiliary hydraulic cylinder. The pumped high-pressure oil makes the left cavity of the hydraulic cylinder and auxiliary hydraulic cylinder a high-pressure cavity, and the hydraulic cylinder and auxiliary hydraulic cylinder move to the left. When the hydraulic cylinder reaches the extreme position and stops working, the pump sucks oil from the check valve on the right, and the pumped high-pressure oil returns to the oil tank through the oil filter and overflow valve on the left. When the motor rotates in the reverse direction, the flow direction of pressure oil is opposite to the above direction.
The direction of the pressure difference between the left and right cavities of the hydraulic cylinder and the auxiliary hydraulic cylinder is changed, and the action direction of the hydraulic cylinder and the auxiliary hydraulic cylinder is opposite to the above. The starting hydraulic cylinder in the oil circuit is used to improve the characteristics of the motor. The manual short-circuit valve is used to short-circuit the oil circuit when it is manually operated, so that the hydraulic pump does not play the role of transmission. The oil volume regulating valve can improve the synchronous action of the hydraulic cylinders of the main engine and auxiliary engine when switching turnouts.
From the perspective of structure, the main causes of oil circuit failure are oil circuit blockage and poor sealing of oil circuit system, resulting in local oil leakage. In recent years, there are few oil circuit blockage faults. This fault can be avoided as long as the oil circuit system is clean and free of sundries during the assembly and installation of turnout, that is, the oil circuit fault is mainly oil leakage fault. The oil leakage fault is divided into internal leakage and external leakage. The internal oil leakage mainly occurs in the hydraulic cylinder or the one-way valve and overflow valve are not tightly closed, and the external oil leakage mainly occurs in each connector, hydraulic pump and end covers on both sides of the hydraulic cylinder. The above fault phenomena, causes and treatment methods are listed in the table below.
Analysis of oil leakage fault of switch machine
|
type |
project position |
Fault phenomenon |
Cause of failure |
processing method |
|
within Department leak oil |
Hydraulic pump |
The pressure in the system is not enough, the turnout cannot be switched normally, the overflow current is low, and there is abnormal sound during rotation |
The internal wear of the hydraulic pump is large, and the amount of high-pressure oil discharged during rotation is insufficient, which flows back to the low-pressure chamber |
Replace the hydraulic pump |
|
Check valve |
When the pressure in the system is insufficient and the turnout cannot be switched normally, when the hydraulic station can switch the turnout, there is oil injection sound in the oil tank and the motor operates normally |
① The steel ball is not closed tightly and the valve core has burrs; ② Loose closing due to sundries stuck in the one-way valve core; ③ The connection between the valve and the oil circuit board is not sealed |
① Replace the steel ball valve core; ② Disassemble the check valve to remove sundries or tap the nut above the check valve to reverse the motor and overflow to make the oil circuit unblocked; ③ The valve can be loosened and tightened. If the seal is not tight, replace the O-ring |
|
|
Relief valve |
The turnout cannot be switched normally, the overflow pressure cannot be adjusted, and the motor operates normally |
① Loose closing due to sundries blocking; ② The valve seat and oil circuit plate are not sealed; ③ The O-ring on the sealing surface of valve core and valve seat is damaged; ④ The spring elasticity decreases; ⑤ The sealing at the adjusting rod is not tight; ⑥ The filter element installed in the valve is poorly fastened or not sealed |
① Open and remove sundries; ② Fasten and replace the O-ring seal; ③ Replace the O-ring seal; ④ Replace the spring; ⑤ Replace the O-ring; ⑥ Tighten the loose part and replace the O-ring if the seal is poor |
|
|
Hydraulic cylinder |
The motor operates normally, the hydraulic cylinder cannot be in place, and the overflow current cannot be adjusted |
① The upper hole of the piston rod in the hydraulic cylinder is damaged by YX shaped sealing ring ② the cylinder barrel of the hydraulic cylinder is strained |
① Replace the sealing ring or directly replace the hydraulic cylinder; ② Replace the cylinder barrel or directly replace the hydraulic cylinder as a whole |
|
|
Outside Department leak oil |
Manual valve |
The turnout cannot be switched normally, and there is oil injection sound there |
The conical valve core and valve seat are not tightly closed, and the valve core surface is not worn smoothly |
Replace the manual valve |
|
Hydraulic pump |
During normal conversion, oil seeps out during rotation |
The external connection of the hydraulic pump to the motor shaft is not sealed |
Replace the hydraulic pump and replace the O-ring after removal |
|
|
各连接头处 |
由于松动，转换道岔时有油渗出，用手摸有油，且油箱内油量减少明显 |
①松动；②连接处密封件封闭不严 |
①拧紧松动部位；②更换该密封件 |
|
|
液压缸 |
转换道岔时，活塞杆上有油带出，机内有油渗出 |
①端盖上轴用YX形密封圈损坏不密封；②端盖上O形圈不密封 |
①更换该处YX形密封圈；②更换该处O形圈 |
|
|
活塞杆 |
机内有油渗出 |
①活塞杆变形；②活塞杆腐蚀 |
更换活塞杆或整体更换液压缸 |
|
|
手动阀 |
该处有油渗出 |
①阀芯杆上O形圈损坏，封闭不严；②阀芯压帽处组合垫坏 |
①更换该密封圈；②更换该处组合垫 |
|
|
油箱 |
液压站内有渗油现象 |
油箱在加工过程中有砂眼或焊接不严 |
更换油箱 |
It can be seen from the above table that most oil leakage faults can be handled without switching the turnout, while it takes a long time to replace the hydraulic pump, oil tank and hydraulic cylinder. Full preparations should be made when dealing with such faults. After replacing the seals of the connecting parts at the oil leakage position, the loading and pressurization test must be carried out. The specific method is: clamp 4mm pieces at the switch rail to operate the turnout. When the turnout is not locked, the motor rotates to increase the pressure in the system, and then check whether there is oil leakage at the replaced seals.
The following points shall be noted during routine maintenance:
① When the oil tank is short of oil, be sure to use the oiler to add oil.
② When replacing the oil pipe and connector, ensure that the connector is clean and free of sundries. When tightening the connector, it is better to tighten it properly without excessive force.
③ During daily maintenance, it is important to check whether there is oil leakage at the connection by hand and eye.
④ The overflow pressure shall be strictly adjusted within the specified range and shall not be too large, so as not to cause poor operation of the oil circuit system.
⑤ Apply lubricating grease to each mechanical moving part every year.
In this way, the application quality of hydraulic switch machine can be improved and improved to ensure the safe application of turnout.
