Abstract: A single-stage servo valve using direct piezoelectric actuator drive is proposed. It takes advantages of the higher bandwidth and resolution. The structure of the valve is compact and the antipollution capability is perfect. The large stroke multilayer piezoelectric actuator is served as the drive element that drives the power-stage spool directly. Bidirectional control of the spool is realized by the spring plate mechanism and single multilayer piezoelectric actuator. The displacement of the spool is measured by strain gauge which is bonded to the spring plate mechanism. The spring plate is analyzed by finite element method. Piezoelectric direct drive servo valve prototype is trial-manufactured and tested. The results show that the bandwidth is up to 1 kHz. The new servo valve can be applied to many high response occasions such as high frequency vibration experimental bed, durability test bed. It will enhance the response characteristic of these systems.

Key words: Direct drive, Electro-hydraulic servo valve, Piezoelectric actuation, Spring plate mechanism