Crane multi directional valve control strategy teaching

For the truck crane, excavator, loader and so on, the hydraulic cylinder in the whole working process, the load direction remains unchanged. Therefore, in the process of crane operation, the crane multi directional valve control is particularly important, then how to carry out the control of multi directional valve of the crane well? Don't worry, little book presents bora.

Two basic control strategies of double spool multi directional valve. Because of the flexibility of the two spool control of the dual valve of the reversing valve, the flow control, pressure control or flow pressure control can be adopted for the two oil ports respectively. Two simple control strategies are introduced.

1, multi directional valve load direction changes in the work process

In this case, the "oil inlet side pressure control, the oil side flow control", in the hydraulic cylinder with the side of the rod cavity pressure control, no rod side flow control.

If the load direction is constant, the flow control of the oil outlet is adopted, and the bidirectional balance valve can be replaced by a hydraulic check valve, so as to improve the stability of the system. The pressure controller is used to maintain a lower reference pressure on the inlet side. On the one hand, the efficiency of the system is improved; on the other hand, no cavitation occurs in the system.

Multi valve in order to change the direction of the load of working mechanism can be well controlled, another PI controller will be applied to the rod chamber of the pressure controller, when the load direction changes, the rodless cavity pressure will be reduced; if still rod chamber to maintain a very low pressure, when the load is large, the hydraulic cylinder will be the opposite direction.

At this time we can change PI controller to monitor the increase in non rod chamber pressure, when the PI controller to detect rodless cavity pressure is lower than the reference value, multi valve will increase the cavity pressure control rod set pressure, thus ensuring the normal operation of the system.

2. The load direction of the multi directional control valve remains unchanged during the whole working process

Crane luffing cylinder in the process of its force, the load direction remains unchanged, so we can take the hydraulic cylinder with rod control pressure control, no rod cavity flow control strategy.

No flow control rod through the test chamber connected to the non rod side chamber before and after both sides of the differential pressure valve, and then according to the required flow into or out of the number, the calculated valve opening size; rod side by side pressure control, which maintain a low pressure, making more energy efficient.

Since the flow control is adopted in the rodless cavity, the balance valve used in the original control system can be replaced by a hydraulic check valve. This can eliminate the system instability caused by the balance valve, so as to improve the system stability.