Abstract: An electrically driven variable displacement servo pump is designed to meet the requirement of dual-variable control to adjust the motor speed and pump displacement synchronously in integrated electro-hydrostatic actuator(EHA). The electrically driven variable displacement mechanism is designed to replace the hydraulic servo mechanism of the conventional servo pump. The driving force of variable displacement mechanism of the servo pump is analyzed, and a DC servo motor is selected as the executive unit of the variable displacement mechanism, which drives the swashplate directly with a reducing mechanism and a segment gear. The swivel angle of the swashplate is adjusted to change the displacement. The mathematical model is created and the simulation result shows that the displacement of the designed servo pump can be adjusted rapidly without overshoot, the adjusting time and the frequency response under small-signal can meet the system’s requirement.

Key words: DC servo motor, Electrically driven variable displacement, Electro-hydrostatic-actuator(EHA), mechanism, Servo pump