An Approach to Combine an Independent Metering System with an Electro-Hydraulic Flow-on-Demand Hybrid-System

Abstract

By combining an electro-hydraulic flow-on-demand system with an independent metering of the actuators in- and outlet, a higher efficiency and a better controllability compared to conventional hydraulic-mechanic load sensing systems can be reached. It also enables the integration of a hydraulic accumulator to recuperate energy due to active loads. This paper presents an alternative control strategy for this kind of hydraulic propulsion systems. Con- nected with the pump and during passive loads the meter-in flow controls the velocity of the actuator. Otherwise the velocity control is achieved by the meter-out flow while the oil flows into the accumulator or tank. Exemplary this system is simulated for a mobile forestry crane. Further steps are building up a test bench for optimization and validation as well as an imple- mentation into a real machine for testing the suitability in use.