Improving performance of pump-controlled hydraulic circuits for single-rod actuators: conceptual study

Abstract

Abstract Pump-controlled hydraulic circuits are more efficient than conventional valve-controlled ones. Pump-controlled hydraulic circuits for double rod cylinders are well developed and, presently, implemented in many applications including aviation. Nevertheless, current pump-controlled hydraulic circuits for single-rod cylinders encounter performance issues during specific operating conditions. Pressure and actuator velocity oscillations are encountered when operating in this critical zone. Different concepts, techniques and designs are proposed by researchers to overcome such vibration issues. In this research, three different concepts to overcome the reported oscillation problem in these circuits are presented; namely: (1) shifting of critical zone into lower loading ranges, (2) applying selective leakage, and (3) applying selective throttling. Simulation studies indicated that the new concepts alleviated the oscillation issue of the common pump-controlled circuits, and improved their performances. The second and third concepts, in particular, were capable of eliminating the whole critical zone. The first concept reduced the area of the critical zone in the load-velocity plane and lessened undesirable effect of oscillations. Simulation studies further proved the enhanced performance of circuits that applies these concepts as compared to previously-designed circuits.