Thompson, B., Yoon, H., Kim, J., and Lee, J., "Swing Energy Recuperation Scheme for Hydraulic Excavators," SAE Technical Paper 2014-01-2402, 2014, doi:10.4271/2014-01-2402.
Due to the high demand of fuel efficient construction equipment, significant research effort has been dedicated to improving excavator efficiency. Among various possibilities, methods to recuperate energy during cab swing motion have been widely examined. Electric and hydraulic hybrids designs have shown to greatly improve fuel efficiency but require drastic design changes. The redesigned systems thus require many hours of operation to offset the manufacturing costs with fuel savings. In this research, a relatively simple swing energy recuperation system is presented using an additional accumulator, fixed displacement hydraulic motor, and control valves. With the system, hydraulic fluid is stored in an accumulator, and a simple controller opens a valve to allow the stored energy to assist the engine in running the main pumps. Using various accumulator capacity and hydraulic motor displacement combinations, the recuperation system was simulated for six cycles of a digging and dumping operation. The simulation results show that an optimum configuration reduces the swing energy consumption by 48% and the total excavator energy by 17% during digging and dumping operations.