Measurements and Simulations to Evaluate Strategies for Improved Energy Efficiency of a Reach Stacker, Forwarder and Wheel Loader

Abstract

As the boom on for example a conventional reach stacker, a forwarder or a wheel loader is retracted and lowered, the entire potential energy of the boom and the load is wasted and converted into fluid heat in the control valves. To reduce the energy consumption and power installation requirements, one possible solution is to compensate for the empty weight, for example by utilising a spring or gas accumulator. By integrating a gas accumulator into the piston rod of the boom cylinder, it is possible to improve the energy efficiency on existing equipment just by changing the boom cylinder. This solution can be used in conventional hydraulic systems but it also has potential to reduce power consumption in more complex electric or hydraulic potential energy recuperation solutions. A number of load handling sequences have been simulated in SimulationX software using a conventional hydraulic reach stacker load handling simulation model and simulation results have been compared to measurements. The simulation results show a good overall compliance with reality. The simulation model can provide detailed information about how large the losses are in different components of the system. By modifying the model and utilise the measured data to get a relevant loading cycle, it is possible to evaluate strategies for improved energy efficiency. Performed simulations indicate that it is possible to further improve the energy efficiency of the system by adding a cylinder and accumulator to recuperate energy when lowering the boom. That also enables the possibility to downsize and reduce the cost for hybrid solutions.