Advanced Energy Management of a Novel Independent Metering Meter-Out Control System: A Case Study of an Excavator

An independent metering (IM) system is a promising alternative to the conventional loadsensing (LS) system. However, the common meter-in control method has impeded further improvement in energy efficiency and investment costs. This paper presents a novel energy management algorithm that combines meter-out (MO) valve control with pressure/flow hybrid pump control. First, the energy-saving performance and dynamic characteristics are analyzed. Then, by designing a coordinate control between the pump and valves, the system has mode switching, MO flow/pressure control, flow distribution, anti-flow saturation, and electronic overload protection capabilities. Compared with the general IM control coupling with a LS system, the proposed method has fewer throttling losses, better dynamic control, and higher application adaptability. This study is applied to a hydraulic-mechanical coupling model of a 2-ton mini excavator to compare the proposed control system with an LS system. Typical continuous actions, such as digging and dumping, are conducted to analyze energy efficiency and controllability, and some special operating conditions, such as flow saturation and pressure/power overload, are also studied.