Design of a novel energy efficient hydraulic tube bender

Abstract

Generally speaking, hydraulic control systems can be divided into two different driving concepts. The first one is the wellknown valve-controlled system and the second one is the pump-controlled system. The former possesses the feature of fast dynamic response. However, the poor energy-saving performance is its major fault. On the contrary, the pump-controlled hydraulic system has the significant advantage of energy-saving which meets the current demand in modern machine design. In this paper, the simulation analysis using Matlab/Simulink and DSHplus for a newly developed energy-saving hydraulic tube bender is conducted. Instead of the conventional fixed displacement hydraulic pump, the new hydraulic tube bender utilizes an internal gear pump with AC servomotor as its driving power source. In the new energy-saving hydraulic circuit, the use of conventional pressure relief valve is no longer necessary since the demanded flow-rate and pressure output can be precisely obtained by continuously changing the speed of the AC servomotor. In addition, from the simulation results, it is shown that the energy-saving performance of load-sensing control scheme is somewhat better than that of constant pressure control scheme. Furthermore, the simulation results also show that the newly developed hydraulic tube bender can save up to 40 % of energy consumption in a working cycle as compared to the conventional hydraulic tube bender.