Electrohydrostatic actuator and method of controlling and damping hydraulic actuator

摘要

An electro hydrostatic actuator (EHA) (102) comprises a hydraulic pump (106) and an electric motor (104) driving the hydraulic pump (106) to supply hydraulic fluid to a hydraulic actuator (112). The hydraulic pump (106) comprises an inlet and an outlet for hydraulic fluid and an active fluid flow path arranged therebetween such that, in an active mode of operation when the pump (106) is driven by the electric motor (104), hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The hydraulic pump (106) further comprises a bypass flow path arranged between the pump inlet and outlet, such that, in a damping mode of operation, hydraulic fluid is able to freely flow between the inlet and outlet in either direction. The electric motor (104) comprises a moveable member (148) arranged to move within the motor (104) such that, when the motor (104) is energised so as to drive the pump (106) in the active mode of operation, the member (148) has a blocking position that acts to block the bypass flow path, and when the motor (104) is not energised the member (148) moves within the motor (104) to open the bypass flow path in the damping mode of operation.