A High Flow Rate and Fast Response Electrohydraulic Servo Valve Based on a New Spiral Groove Hydraulic Pilot Stage

Abstract

High flow rate electrohydraulic servo valve is widely applied in hydraulic servo systems. Typical high flow rate servo valve is three-stage nozzle flapper pilot structure which is complicated, unreliable, and highly costly. This study proposed a new two-stage structure high flow rate and quick response electrohydraulic spiral pilot servo valve (ESPV) using a novel hydraulic full bridge spiral pilot stage (FBSPS) as hydraulic amplifier. Its structure is simpler than traditional servo valve which could increase reliability. A design parameters optimization method for servo valve is proposed. It is using an optimization objective function which can balance dynamic performance, static performance, and pilot state efficiency for different design objectives. The particle swarm optimization (PSO) method was applied to get the best key design parameters of ESPV. A research prototype was developed based on the optimized parameters for fast response. The experimental results indicated that the frequency bandwidth (−3 dB amplitude attenuation and −90 deg phase lag) of the ESPV is up to 150 Hz at 20% of full range. This frequency response performance is competitive with existing servo valves, and the simpler structure can improve reliability and reduce cost. Thus, it may have great potential in hydraulic servo system with high reliability requirement, such as aircraft hydraulic servo control system.