Design and Verification of a New Energy Saving Electric Excavator

The aim of this paper is to propose a new type of excavator - electric excavator (ELEX) - with energy saving capacity using six quasi independent electro-hydraulic actuators (EHAs). The quasi-independent configuration minimizes hydraulic interferences among the actuators and losses which occur in traditional hydraulic excavators (HYEXs). In addition, the boom/arm/or bucket cylinder is driven by a closed EHA system, so that potential energy accumulated at "up" positions can be recuperated and converted into electricity via the EHA generator when the boom/arm/or bucket goes down, respectively. Kinetic energy of the upper slewing body also can be recovered and converted into electricity when a slewing stop happens. A 5-ton excavator using a hybrid boom system (HBS) was analyzed, developed as an experimental ELEX (EELEX) for evaluating the proposed ELEX. A control strategy for the 5-ton EELEX was built to operate the machine to follow desired performances. Higher working efficiency and less energy consumption of the EELEX have been clearly verified through simulations and experiments in comparison with the conventional 5-ton HYEX.