Realization of direct flow control with load pressure compensation on a load control valve applied in overrunning load hydraulic systems

This paper presents the realization of direct proportional flow control with load pressure compensation feature on a LCV (load control valve). Proportional flow control performance means the flow through the LCV is proportional to the pilot pressure in the control stroke. Proportional flow control decides the overrunning load lowering speed control performance of the whole system. The load pressure compensation feature means when the load pressure is too high, the flow of the LCV can be restricted about the maximum rated flow. The load pressure compensation feature is important to the safety of the system. That is because large flow means undesired fast lowering speed, which will cause accident in applications, especially those large mass overrunning load systems. In this paper, the flow control performance was simulated and the parameter relationship of the orifices was derived, which is the base for the optimizing of the compensation orifice. In addition, load pressure compensation feature was simulated and the compensation orifice size was optimized. Finally, an LCV built according to above methods was tested on a test rig. Experiment data validates the methods presented and the realization of direct flow control with load pressure compensation feature gives guidance for the direct flow control performance development of other valves.