Improving the Response of an Electrohydrostatic Actuation (EHA) System Using a High-Pressure Accumulator

Abstract

This paper proposes an (EHA) system driven in three modes to improve the low reactivity of the existing EHA system. By using a small high-pressure accumulator, servo valve, and mode switching valve, the circuits can be changed so that they are suitable for each mode according to the driving conditions. Each of the three modes consists of the EHA mode, the hybrid mode, and the charging mode, and the EHA mode operates on the same principle as the existing EHA system. The hybrid mode is activated when high-speed position control is performed, and with the help of an add-on servo valve controller, the control volume of the hydraulic cylinder can be stiffened quickly while minimizing the use of high-pressure fluids. The charge mode serves to periodically charge the accumulator under motionless conditions in applications that allow piston holding. Simulations and experiments confirm that the responsiveness of the proposed system is much improved compared to that of the existing EHA system.