I would like to ask about the working principle of the air circuit distribution valve and how to diagnose its faults
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This is the pneumatic control system for the pneumatic track ball valve (Figure 1). The rectangular structure in the middle serves as the instrument air duct distribution valve, featuring a one-in-two-out design; the internal piston is controlled by the left and right solenoid valves to enable air flow connection on the left and right sides (Figures 2-3). Currently, after the solenoid valve operates, the distribution valve does not function properly. Upon disassembling the distribution valve, no abnormalities were found inside it. I would like to ask the experts what could be causing this issue with the distribution valve’s operation? .
For a double-acting 2/5-way solenoid valve, you need to determine whether the problem lies with the solenoid valve or the cylinder
It’s a two-way three-port valve; since the valve is quite large, the two sides of the three-port structure are controlled by solenoids that open and close it, with air pressure being used to drive the intermediate shaft – rather than the coil driving the intermediate shaft (as the pipes are too large for the coil to have an effect on them). If the movement is not smooth, check whether there are any problems or damage to the seal that ensures air tightness; remove it and try pushing it manually to see how it performs. Also, check for any air leaks. If nothing happens, check the solenoid valve and for air leaks; you can open some areas to see if air is passing through.
Theoretically, there should be two five-way valves; the image doesn’t show the side of the air valve, but there are likely two exhaust ports on either side of the main air inlet. Exhaust is necessary when pushing back and forth. Poor performance can also be caused by problems with the cylinder; if the cylinder is leaking air, this too can lead to poor performance. An external air supply tube can be connected to conduct a test by supplying air to one side only.
I agree with what was said on the third floor: it’s similar to two two-position three-way solenoid valves, rather than one two-position five-way solenoid valve with dual control, as can be seen from the gas circuit connections. The air supply to the middle channel of the distribution valve is under pressure control; even if the solenoid valve operates, no gas can enter the valve, and it remains in its holding position. If the individual test valve operates normally, then try replacing the distribution valve.
The only way to analyze such faults is through elimination. If the main valve can be opened and closed, a direct connection to the source should be established in order to test whether the valve operates smoothly when venting in both forward and reverse directions. Next is testing the solenoid valve, by applying power and removing power to it respectively, to check whether its operation is normal. After these two tests, a conclusion should be reached. It is more convenient to replace the solenoid valve for testing. If it works properly, it indicates a fault with the solenoid valve; if it does not work properly, testing of the main valve is still required. For reference.
I have no objection; indeed, two two-position three-way solenoid valves are used to control the operation of a two-position five-way pneumatic valve. However, the main air path is a two-position five-way valve, and the exhaust port should be located next to the solenoid valves. A filter-regulator valve is installed on the middle path, and it is not used for pressure control. It’s not clear how to tell if the distribution valve is not working properly; it seems that the valve indeed isn’t functioning correctly, so it’s necessary to determine exactly which part is the problem.
It’s the difference between pilot-operated and direct-acting types, right?