During on-site maintenance, we will encounter that the
solenoid valve does not convert and the cylinder does not move. What should we do then? First of all, it is necessary to determine whether there is a power supply. Generally, the rated voltage of the solenoid valve is AC 220v or DC 24v. Then, when using DC power to drive the solenoid valve, the positive and negative poles must be connected correctly, and the power indicator will not light up when connected incorrectly. If the different voltage levels are connected incorrectly, the light-emitting diode will be burned, and the coil will be seriously burned.
Measure whether there is a power supply. If the power supply is normal, it means that there is no problem with the control circuit. The problem is on the side of the solenoid valve and the cylinder. Next, you need to measure the resistance value of the coil, first measure its on-off with a multimeter, and the resistance value approaches zero or infinity, which means that the coil is short-circuited or open-circuited. If the resistance value of the measuring coil is within the normal range (different solenoid valve models, the normal coil resistance value is different, some are tens of ohms, and some are hundreds of ohms; if you are not sure what the normal resistance value is, you can make it different from other nearby ones. The same type of solenoid valve compares the lower resistance value), and the power is magnetic, it can be judged that the coil is good, and the problem lies in the solenoid valve spool or cylinder.
Because the compressed gas provided by some factories contains moisture and many other impurities, the pneumatic triplet does not have the desired effect, and the solenoid valve will inevitably be stuck by impurities for a long time. As a result, the solenoid valve is stuck and cannot be converted. Generally, we can judge that we can use a small word to poke the manual button of the solenoid valve. The manual design is for easy debugging. After pressing it, it will The toggle spool (the main spool of the direct-acting solenoid valve, the pilot spool of the pilot valve) achieves the same effect as the solenoid valve coil energizing the toggle spool. Experiment to see if the solenoid valve is stuck or not. If the solenoid valve is stuck, we can clean the solenoid valve cavity and clean the solenoid valve spool. If the spool is damaged and other serious problems, the spool or solenoid valve can be replaced. Finally, power on to test whether it is good or not.
Another type of fault is the blow-by gas inside the solenoid valve. How to judge whether it is the blow-by gas of the solenoid valve or the blow-by gas of the cylinder. Let’s briefly talk about their working principle. Take the two-position, five-way solenoid valve as an example. Two-position means that its spool has two positions. Two outlet holes 2 and 4, two exhaust holes 3 and 5. The working principle of the solenoid valve is the initial state, 1, 2 intake; 4, 5 exhaust; when the coil is energized, the static iron core generates electromagnetic force, which makes the pilot valve act, and the compressed air enters the valve pilot piston through the air path to start the piston. , In the middle of the piston, the sealing circular surface opens the channel, 1, 4 intake, 2, 3 exhaust; when the power is cut off, the pilot valve is reset under the action of the spring and returns to its original state. The blow-by of the solenoid valve is caused by the poor sealing of the spool sealing ring inside, which causes air to come out of the 4 and 2 air outlets, so the phenomenon of the solenoid valve blow-by is that the cylinder cannot reach the position or move.
The working principle of the cylinder is simpler. We introduce the double-acting cylinder: the two sides of the cylinder piston are connected to the 2 and 4 holes of the solenoid valve to provide pressure to achieve forward or backward action. When two sides of the piston alternately have compressed air entering from 1, 4 and discharging from 2, 3 or 2, 3 entering 1, 4 and discharging, the piston moves in two directions, and the speed of movement in both directions can be controlled by adjusting the air pressure . Generally, we choose the exhaust adjustment speed. The cylinder is composed of cylinder barrel, end cover, piston, piston rod, and sealing ring. Generally, the blow-by gas of the cylinder is the damage of the sealing ring in the cylinder. The left and right cavities blow-by gas each other, which causes the piston to have no pressure. Discharge from 2 and 3. You can feel the gas in 3 places until the gas comes out. When the cylinder seal is in good condition, the gas 1 and 4 enter the left chamber of the cylinder, and the left and right cavities are sealed without blowing gas. Its fault phenomenon is very similar to the blow-by gas of the solenoid valve. The difference is that the blow-by gas of the solenoid valve is discharged from the 4 and 2 air outlets at the same time, while the blow-by gas of the cylinder is always discharged from the cylinder.
Some maintenance is worth noting, some of our solenoid valves with a base need to check the sealing ring of the base, and the sealing ring will age for a long time. Aging seals can cause air leakage and blow-by in the solenoid valve. At the same time, some solenoid valve end caps are connected to the pressure regulating valve, and sometimes the pressure regulating valve is closed or blocked, which will result in the inability to exhaust gas and no action. Some moving mechanical components such as the armature of the solenoid valve head and the spring will also be damaged over time.
