Servo valve failure reasons and exclusion
Servo valve failure often in the electro-hydraulic servo system debugging or working under abnormal circumstances found. So here are sometimes system problems, including amplifiers, feedback agencies, implementing agencies and other failures, and sometimes it is indeed a servo valve problem. Therefore, we must first figure out the system problems, or servo valve problem. Common way to solve this problem is: First, the conditional removal of the valve, the test bench to test what you can. Second, in most cases no such conditions, then a simple method is to open the system, stand-alone independent DC power supply, the multimeter to the servo valve for positive and negative different magnitude of current output from the valve to determine whether the valve Problems, what is wrong. For example, if the internal leakage of the actuator is too large, it will cause the system to slow down, the hysteresis is serious, or even unable to work; the feedback signal is open or malfunctioning, etc., the amplifier problem has the distortion of the output signal or Not working, system problems ominous talk here, the following mainly talk about valve failure. (1) the valve does not work for a number of reasons: motor coil disconnected, desoldering; there is also into the oil or out of the oil port reversed. Then there may be pre-stage blockage, making the spool just stuck in the middle of the dead zone, spool stuck in the middle position, of course, less likely. The motor windings are connected in series or in parallel, and the magnetic force formed by the two coils just cancels out. (2) The valve has a fixed output but is out of control Cause: The pre-stage nozzle is blocked, the spool is stuck by the booty and the valve body is stuck causing deformation, etc., or the internal protection filter is blocked by the booty. To replace the filter, the factory cleaning, repair. (3) The valve is unresponsive and the response is slow. The reason is that the pressure of the system oil supply is reduced and the filter is partially blocked. Some valve zeroing mechanisms are loosened and the other parts of the motor are loosened or the moving coil of the moving coil valve and the control valve core Between loose. System implementation of power components within the leak, is another reason. In addition the oil is too dirty, poor valve resolution, widening hysteresis is one of the reasons. (4) High frequency of vibration and noise in the system Cause: The amount of air mixed in the oil is too large and the oil is too dirty. The system gain is too high, power supply noise from the amplifier, servo valve coil and valve housing and ground Line insulation is not good, is not through, flutter signal is too large or with the system frequency caused by the resonance phenomenon, and then the system is relatively low and chose too high frequency servo valve. (5) The valve output suddenly neglect, can not be continuous control, into a "switch" control. Cause: Servo valve feedback mechanism failure, or system feedback off, otherwise there is some positive feedback phenomenon. (6) oil spill causes: mount surface processing quality is not good, can not seal. Valve port seal quality problems, valves and other seals at the plug damage. If the oil leaks between the motor cap and the valve body, the spring tube may rupture and the internal tubing ruptures. Servo valve troubleshooting, and some can be ruled out, but many failures to the valve to the production plant, the test bench on the rework debugging, and again: Do not disassemble the valve, it is very easy to damage the servo valve components. Servo valve with more units can be equipped with a simple test bed to determine whether it is a system problem or valve problems, the valve has any problems, can we use.
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