Nonsymmetrical Flow Compensation Using Hydraulic Accumulator in Direct Driven Differential Cylinder Application

This paper presents a novel hydraulic setup, direct driven hydraulics (DDH), which consists of two pumps on a common axis driven by a servomotor. These pumps are directly connected to each chamber of a differential hydraulic cylinder. The pumps are dimensioned so that the respective nominal sizes corresponds to the expected flows of each cylinder chamber. However, the dimensioning of the pumps are slightly off, leading to an excess rise of pressure in the B-chamber. This paper investigates if the implementation of a hydraulic accumulator can mitigate this mismatch problem. A Matlab/Simulink model was created and utilized for simulating the optimal accumulator parameters for energy efficiency. The optimal alternative was implemented to the research setup and energy efficiency measurements are performed with various loads and different ambient temperatures. The results shows that this solution was a viable alternative and that the energy efficiency of this setup was improved.