LAUSR

Abstract Tightening of emission rules and a desire to improve energy efficiency pushes even further the need for hybridization of non-road mobile machinery (NRMM). Consequently, this paper illustrates potential of the application of directly driven hydraulic drive (DDH) for NRMM from an energy efficiency point of view. The control of the DDH system was implemented directly with a servomotor driving a pump without conventional hydraulic control valves. Angular speed of the servomotor, in-coming oil flow from the pump, and out-going flow to the hydraulic motor determined the velocity of the double-acting cylinder piston. An earlier study by the authors presented that the hydro-mechanical losses were dominant in the original DDH setup. Resulting theoretical investigation indicated that the best scenario efficiency for DDH was estimated to be 76.7%. Therefore, this paper provides a detailed analysis based on Sankey diagrams of various powertrain topologies with DDH. This study of powertrains illustrated that DDH has the highest impact with 174% efficiency improvement with an electric NRMM powered by batteries instead of a conventional topology.