Analysis of Faults in the Speed Control Valve of the Hydraulic Station System

In this article, Dalan Hydraulic willze the fault issues of the throttle valve in the hydraulic station system. When adjusting the throttling section, if the flow rate in the outlet chamber does not change, the main reae the radial jamming of the spool and the failure of the throttling section. If the pressure reducing spool or the throttling spool jams radially in the fully closn, adjusting the opening of the throttling port will not change the flow rate in the outlet chamber. When the throttling adjustment section fails, the adjusting screw cannot move axially,ing the flow rate in the outlet chamber to remain unchanged. When spool jamming or throttling adjustment section failure occurs, cleaning and repair should be performed.

For throttling adjustment type sntrol valves, after the throttling port is adjusted and locked, flow instability sometimes occurs, especially at the minimum stable flow rate. The main reasons are loose locking devices, partialckage of the throttling port, increased oil temperature, too low minimum pressure difference between the inlet and outlet chambers, and reversed inlet and outlet connections.

1. To ensure the control accof the speed control valve on flow (i.e., the speed of the actuator cylinder), a certain pressure difference (minimum pressure difference between inlet and outlet chambers, referring to the pressurence between the valve inlet and outlet chambers when the throttling port is fully open and passing the nominal flow) must be guaranteed. For ordinary speed control valves, the pressure difference s not be less than 0.5 MPa. For high-precision speed control valves, the pressure difference can reach 1 MPa. Additionally, when the ambient temperature changes signtly, a speed control valve with temperature compensation should be selected. Note: If the pressure difference is too low, the pressure reducing section cannot work normally, cannot effectively pressure compensate the throtg valve, and thus affects the stability of the flow in the hydraulic station system.

2. If the actual flow rate through the valve is determined to be too small, it will lead toting a valve specification (capacity) that is too small, causing excessive local pressure loss in the valve, high oil temperature, and other drawbacks; in severe cases, it can cause the hydraation system to fail to work normally. The actual flow rate through the valve (not the pump flow rate) should be used as one of the main parameters for valve selecthe operating pressure and flow rate of the control valve should not exceed its rated values. If the operating pressure and flow rate of a flow control valve exceed its rated values, iasy to cause hydraulic jamming and liquid dynamic forces, which have a negative impact on the working quality of the control valve.

4. Note that ordinary speed control valves exhibit flow jumping duing startup, which affects the smoothness of the actuator cylinder speed. Therefore, corresponding measures should be taken.