Egelja, A., Blum, D., and Patel, K., "Hydraulic Hybrid Excavator System Development and Optimization Based on Energy Flow Analysis and its Performance Results," SAE Technical Paper 2015-01-2851, 2015, doi:10.4271/2015-01-2851.
Many off-highway machines, including hydraulic excavators, perform cyclical motion in their everyday activities where there is significant acceleration, deceleration, load lifting and hydraulic implement lowering. During that time in conventional off-highway machinery, most of the potential or kinetic energy is dissipated as heat instead of being captured and reused. When these opportunities are well understood and consequently machine systems are designed and integrated properly, fuel efficiency improvements could reach double digit values. It should be noted that the mentioned machine efficiency improvements will still vary depending on the machine size, its application and the characteristics of machine system(s) being applied.An approach for excavator energy flow analysis, coupled with rapid machine control design changes directed to minimization of energy losses is discussed. This paper describes technologies that are applied on the 30 ton hydraulic excavator, which help conserve, optimize, capture and reuse machine energy in a variety of machine applications. Virtual product development tools not only helped narrow initial design options, but also greatly reduced time needed to develop machine controls that resulted in excellent machine performance (efficiency, productivity, and controllability). The applied development process illustrates ability to achieve both, good machine performance prediction in the early stage of the development and to shorten machine development time. Machine productivity study results and data obtained from various customer machines confirmed double digit fuel efficiency improvements.