Electric plug valve failure case analysis process

1. Fault phenomenon

     Active oil electric plug valve RDK-64A (Φ62) 1# product in the ground joint test, the valve stops working when the valve works from the fully closed position to the half-open position, and the motor heats up. It is confirmed by on-site power-on inspection that the working current of the product exceeds 3A, and the valve driving torque measured with a torque wrench is 15N m. At the same time, when the 2# product is energized for review, the electric plug-in valve does not work, and the measured valve driving torque is 12N·m. According to the preliminary judgment of the fault phenomenon, due to the excessive driving torque of the electric plug-in valve valve, the motor has been blocked and burned.

     2. Problem location

     The valve of the electric plug-in valve is disassembled, there are scratches on the valve plate, and the valve shell, rocker arm and other parts are intact.

     Use a torque wrench of 0~30N·m to detect the torque of the valve part in the state of no medium and clamping. The maximum driving torque of the valve from opening to closing is 7N·m, and the maximum driving torque from closing to opening is 6N·m m , less than the rated torque of the mechanism 9N·m , that is, when the valve is no-load and clamped, the electric plug-in valve can work normally.

In order to simulate the working condition at the time of failure, the valve part is clamped on the fuel life test bench, and 0.35M Pa RP-3 kerosene is used to test the torque in this state. The maximum driving torque of the valve from opening to closing is: 7N·m , the maximum driving torque from closing to opening is 15N·m , which is greater than the design torque of the mechanism. Gradually increasing the working pressure, the driving torque of the valve from opening to closing remains unchanged, while the driving torque from closing to opening gradually increases.

     3. Find the problem

     After the above analysis of the structure and working principle of the electric plug-in valve and related disassembly inspections, it can be confirmed that the reason for the failure phenomenon that the product does not work is that the driving torque of the valve from closing to opening is too large, and the mechanism is difficult to drive, resulting in excessive current. Big, the motor burned out.