An electrohydraulic spool valve, comprising: a spool, axially movable within a manifold; a position feedback system provided at a first end of the spool; and an end cap provided on said first end so as to form a first high pressure reservoir between the end cap and the first end of the spool. The end cap provided on the end of the spool partly defines the high pressure reservoir by containing the high pressure fluid in the vicinity of the spool end.

A driving stage of a servo valve, including a hydraulic ejector and a hydraulic receiver able to be moved relative to each other, one of the two hydraulic units being integral with a mobile unit, movable relative to a body of the servo valve through actuation means, characterized in that the actuation means comprise two piezoelectric actuators connected in series. Control device comprising a servo valve comprising such a driving stage.

A servovalve includes a supply port and a control port; a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow; wherein the drive assembly comprises a first fluid channel providing a flow path for fluid from the supply port to a first end of the spool and provided with a first flow control orifice. The assembly also includes a second fluid channel providing a rotating element provided with a cam profile located between the first flow control orifice and the second flow control orifice. The assembly also includes drive means arranged to rotate the rotating element.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port, a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal, and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The drive assembly includes a steerable member moveable by an amount determined by the control signal to cause corresponding movement of the valve spool. The drive assembly further includes piezoelectric actuator means configured to move said steerable member in response to the control signal.

Servo-valve that controls fluid discharged from a nozzle discharge port by displacing the nozzle, and that drives an actuator. The servo-valve includes a receiver provided with a first inflow port into which the fluid discharged from the discharge port flows. At least either the discharge port or the inflow port is a non-circular opening formed such that the amount of change in the area of overlap of the discharge and inflow ports occurring when the nozzle is displaced from the initial position is larger than in cases where the discharge port and the inflow port are of circular form of the same area. The increased amount whereby the area of overlap between the discharge and inflow ports changes when the nozzle is displaced from the initial position lets the fluid flow into the inflow port more quickly, improving the response speed of the actuator.

A hydraulic servo valve comprising a pair of opposing receiving ports, a piston disposed between the pair of opposing receiving ports and an actuator in contact with the piston. The actuator is configured to provide axial movement of the piston in response to being actuated. The piston comprises a pair of opposed openings that are in operable fluid communication with a respective one of each of the receiving ports, and the axial movement of the piston is configured to vary the amount of a fluid pressure communicated between a respective one of the openings and receiving ports.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal; and a jet pipe assembly configured to direct fluid to the ends of the spool to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The jet pipe assembly includes a jet pipe and a connector header fluidly connecting the jet pipe to a nozzle via which fluid is directed to the spool ends. One or more openings is provided in the spool such that fluid from the supply port flows into the interior of the spool and into the jet pipe and to the nozzle via the connector header.

There is provided a method of assembling a torque motor. The method comprises fastening the torque motor to a support such that any magnetic elements of the torque motor are substantially fixed in position with respect to the support, but without securing an armature to the torque motor, locating the armature of the torque motor around a fixed element of the torque motor such that the armature is able to move with respect to the fixed element, moving the armature with respect to the fixed element whilst the magnetic elements of the torque motor are substantially fixed in position with respect to the support, so as to position the armature in an in use orientation or position, and then attaching the armature to the fixed element in the in use orientation or position.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port; a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal; and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The drive assembly comprises a steerable jet pipe moveable by an amount determined by the control signal to cause corresponding movement of the valve spool and the jet pipe terminates at one end in a nozzle and at the other end being in fluid flow engagement with a fluid supply pipe. Movement of the valve spool is caused by fluid flowing from the nozzle to engage with the valve spool.

The disclosure provides a method of securing a feedback spring relative to a spool of a servovalve, the method comprising inserting the feedback spring at least partially into an internal cavity of the spool, inserting two fixing members into the internal cavity such that they each oppose a portion of the feedback spring, bringing the fixing members into respective set positions, such that the fixing members clamp the feedback spring and prevent relative movement between the feedback spring and the spool, and securing the fixing members in their respective set positions, such that the fixing members remain in their clamping positions and prevent relative movement between the feedback spring and the spool.