An electro-hydraulic circuit includes a supply line that connects between a hydraulic supply device that supplies hydraulic fluid and a driving part to be driven by a hydraulic pressure of the hydraulic fluid; a switching valve disposed in the supply line to switch between switching lines for the hydraulic fluid supplied to the driving part; a pilot hydraulic line connected to the switching valve to supply the hydraulic fluid for switching between the switching lines; a check valve disposed in the pilot hydraulic line; a solenoid valve disposed in the pilot hydraulic line to change a supply state of the hydraulic fluid to the switching valve; a sealing material disposed in the switching valve to seal the hydraulic fluid; and a relief valve disposed in the pilot hydraulic line to release the pilot hydraulic pressure

A switching valve includes a sleeve on which a plurality of ports are disposed; a spool that is disposed inside the sleeve to move in an axial direction by a pilot hydraulic pressure to switch between switching lines each serving as a flow channel for hydraulic fluid that is formed by a combination of the ports; a first energizing unit that energizes the spool against the pilot hydraulic pressure; a relief hole that is disposed on the spool to discharge the hydraulic fluid with the pilot hydraulic pressure; a valve body that closes the relief hole; and a second energizing unit that energizes the valve body toward the relief hole of the spool against the pilot hydraulic pressure, and when the pilot hydraulic pressure exceeds a predetermined value, opens the relief hole.

Method for controlling and damping the motion of a hydraulic actuator in an electro hydrostatic actuator (EHA) system comprising an electric motor, a hydraulic pump and a hydraulic fluid circuit connecting the hydraulic pump and the hydraulic actuator includes comprising: energising the electric motor to drive the hydraulic pump to supply hydraulic fluid to the hydraulic actuator through the hydraulic fluid circuit in an active mode of operation; providing a flow path between the hydraulic actuator and the hydraulic pump in a damping mode of operation such that hydraulic fluid can flow via the flow path through the hydraulic pump when the hydraulic actuator is driven by an external force; and determining a desired amount of damping to be applied to the hydraulic actuator in the damping mode of operation and providing the electric motor with one or more energy consuming means configured to provide the desired amount of damping.

A cooling system of an electromechanical actuator is provided. The cooling system includes a housing and a stator located within the housing and defining a central bore. A first body including a sleeve portion is configured to extend into the central bore of the stator, with the first body defining a first chamber including a first cavity within the sleeve portion and a second cavity fluidly connected to the first cavity. A heat sink is provided in thermal communication with the second cavity.

A force fight mitigation system comprising: control means configured to provide a position command to each of two or more actuators arranged to position a surface, the position command indicative of a desired position of the actuator relative to the surface; means to detect the actual position of the actuator relative to the surface in response to the position command; and means to determine an offset between the desired position and the actual position and to store a rigging correction based on the offset; wherein, for each actuator, an offset is determined for each of three or more desired positions.

A hydraulic system of an aircraft may include a system pump configured to provide hydraulic fluid to the hydraulic system at a first working pressure. The hydraulic system may further include a booster pump configured to supply hydraulic fluid to at least one boostable actuator at a second working pressure higher than the first working pressure. The boostable actuator may be operatively coupled to and configured to actuate at least one flight control surface of an aircraft.

The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

A system and method for controlling two or more actuators acting together to move a component or surface includes Two or more actuators engaged with the component or surface to be moved. Each actuator is displaceable to move the component or surface in response to a component or surface position command. Each actuator has an associated actuator controller to receive the position command and to output an actuator displacement command. The system also includes force fight control means configured to determine a force differential from forces, or a pressure differential from pressures measured at each actuator and to derive a speed and/or a current offset signal, and to provide the offset signal to the actuator controllers to modify the actuator displacement commands.

An accumulator assembly for providing hydraulic fluid to an actuator. That assembly includes an accumulator for containing a supply of hydraulic fluid, the accumulator having an exit port via which hydraulic fluid can flow, in use, to the actuator. The assembly also includes a coupling comprising a first coupling part configured to be located at an inlet port of the actuator and a second coupling part arranged at the exit port of the accumulator. The first and second coupling parts are configured to matingly engage to form an open passage for flow of the fluid-between the accumulator and the actuator, and to close the first coupling part when the first second coupling parts are not engaged, so as to prevent flow from the actuator and to prevent air and pollution ingress the actuator.

The disclosure relates to a flight control system comprising at least one hydraulic servo actuator, wherein the servo actuator includes a two-stage electrohydraulic servo valve, wherein the servo valve comprises a pilot stage in which the control current is translated into a hydraulic control pressure, and a power stage in which a valve slide is moved in response to the control pressure in order to adjust the throughflow direction and throughflow cross-section of the valve. The disclosure furthermore relates to an aircraft comprising such a flight control system.