ENERGY SAVING SYSTEM FOR OFF-ROAD MACHINES BY THE USE OF THE MOVABLE COUNTERWEIGHT ENERGY RECUPERATION

Abstract

In this paper, concept of energy saving by the use the special recuperation system for hydraulic excavator is studied. This solution is alternative to commercial projects of hybrid systems, which store energy in the hydro pneumatic accumulators or the super capacitors. Suggested solution includes designed system of active counterweight, which cooperates with working mechanism of machine. The hydraulic circuit of active counterweight is connected with the boom standard hydraulic system. The counterweight mechanism is homothetic to working mechanism of the excavator. The homothetic transformation applies to kinematical structure and positions of the centres of gravity. The homothetic transformation provides to static unloading of boom cylinder by the connected counterweight cylinder. The possibility of energy saving by using movable counterweight was estimated during tests. The key parameters of hydraulic system, such as: cylinders velocity, working pressure, oil flow and another were measured on prepared research stand. The comparison of power consumption for standard and modification system during the same work cycles allowed confirms the correctness of the suggested concept for energy saving system. Energy saving ratios for modified hydraulic circuit was calculated for different velocity of boom cylinder and payloads. The active counterweight system for low velocity cylinder of excavator mechanism is ready to application. The hydraulic circuit for higher value of boom cylinder velocity requires resize a few elements for example supply lines.