Potential Energy Recovery System of Hydraulic Hybrid Excavator

For existing hydraulic hybrid excavators, the loss of energy is still too large and the energy recovery efficiency is not high enough. Concerning these issues, a new hydraulic hybrid excavator potential energy recovery system is proposed within this paper. The energy recovery system uses three-chamber cylinders (TCCs) and accumulators to recover the potential energy of mechanical arms and load of the excavator. The TCC consists of three chambers, including chamber with piston rod, chamber without piston rod and counterweight chamber. The counterweight chamber is connected to an accumulator, which provides average load force. The chamber with piston rod and the chamber without piston rod are connected to inlet and outlet of a variable pump respectively, constituting a pump controlled system together. The mathematical models of load, engine, pump, TCC and accumulator were established in this study. According to the mathematical model, the dynamic response was simulated and the dynamic characteristics of each components were analyzed. The parameter matching of accumulator was proposed as well. Besides, the simulation model was built and the simulation result was carried out. From the simulation, the dissipated energy of each cylinder was obtained and compared with the dissipated energy without potential energy recovery system. According to the comparison, the potential energy recovery system can reduce the dissipated energy of variable pumps by around 30∼60%, and reduce the dissipated energy of engine by around 50%.