2018 Volume 49 Issue 3 Pages 72-79
Water hydraulic systems are an outstanding driving source because they have no risk of environmental pollution and fire hazard. However, conventional water hydraulic systems, as well as oil hydraulic systems, have larger energy loss for pressure loss through mainly control valves. Here, there are two solutions to achieve the energy-saving: reducing the restriction loss through control valves, and applying the energy recovery module with an accumulator. In oil hydraulic systems, the independent metering system which includes two control valves for one actuator to reduce the restriction loss through valves has been proposed. This system applies a variable displacement pump to control the pump supply flow. However, variable displacement pumps have been still at the stage of research and development in the field of water hydraulics because of the internal leakage and the difficulty of selecting materials on sliding parts. In contrast, the energy recovery module can reduce the energy consumption and be applied to water hydraulic systems.
This paper proposes two circuits which achieve each energy-saving solution for water hydraulic motor systems with a fixed displacement pump and compares the control and energy performances of these circuits. According to the experimental results, the pump supply energy of the proposed circuit which reduces the restriction loss could be reduced 40% of that of the conventional system. In contrast, the pump supply energy of the proposed circuit which applies the energy recovery module could be reduced 10% of that of the conventional system.