Abstract: A servo valve includes: a fluid transfer valve assembly comprising a supply port and a control port (PA, PB); 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 means 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 means comprises an elongate member arranged to rotate in response to the control signal. The elongate member has a cam profile in the fluid flow path such as to vary the pressure acting on the ends of the spool as the cam profile rotates.

Abstract: A servo valve comprising: a fluid transfer valve assembly comprising a supply port and a control port (PA, PB); 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 means 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 means comprises a piezo actuator element mounted within and axially movable with the valve spool, the piezo actuator configured to extend axially in response to the control signal to cause corresponding axially movement of the spool.

Abstract: 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.

Abstract: A check valve has a valve housing defining a first valve opening and a second valve opening. A first flapper is pivotably mounted around a first axis for rotation relative to the housing between an open position at which it permits fluid flow through the first valve opening and a closed position at which it prevents fluid flow through the first valve opening. A second flapper is pivotably mounted around a second axis for rotation relative to the housing between an open position at which it permits fluid flow through the second valve opening and a closed position at which it prevents fluid flow through the second valve opening. The first axis is spaced laterally from the second axis. A method is also disclosed.

Abstract: 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.

Abstract: A check valve comprises an annular housing defining a generally circular opening. A plurality of radially extending arms extend across the circular opening from the centre of the valve housing to respective nodes at the periphery of the valve housing. A plurality of cross arms extend between circumferentially adjacent nodes, thereby dividing the circular opening into a plurality of primary, generally triangular radially inner openings and a plurality of secondary, generally segment shaped radially outer openings. A plurality of primary, generally triangular flapper elements close the primary openings and a plurality of secondary, generally segment shaped flapper elements close the secondary openings. Respective mounting posts are arranged at a respective node and a respective hinge pin is mounted between respective circumferentially adjacent mounting posts.

Abstract: A servo valve includes first and second nozzles spaced apart from each other, an elongate control member positioned between the nozzles, and a solenoid assembly surrounding at least a portion of the control member. The elongate control member has a first end and an opposing second end. The control member is configured to translate in response to the solenoid assembly being energised, such that the first end is moved towards the first nozzle and the second end is moved away from the second nozzle or the first end is moved away from the first nozzle and the second end is moved towards the second nozzle.

Abstract: A stop pin for a check valve includes a first end and a second end and extending from the first end to the second end in a longitudinal direction along a longitudinal axis. The stop pin also includes at least one slot therein extending in said longitudinal direction, said at least one slot defining a respective at least one flexible, cantilevered tongue having a free end and a connected end connected to said stop pin.

Abstract: A check valve comprises a valve housing defining a valve opening; and a flapper element. The flapper element has a proximal end, and is pivotally mounted to the valve housing adjacent the periphery of the valve opening at its proximal end for pivotal movement between a closed position, in which it blocks the flow of fluid through the valve opening and a fully open position in which it permits the flow of fluid through the valve opening. At least one spring damping element is located between the flapper element and the valve housing for providing a damping force resisting the pivotal movement of the flapper element towards its open position. The at least one spring damping element being operable to produce a damping force only over a final range of the pivotal movement of the flapper element as it approaches its fully open position.

Abstract: A damping valve for a hydraulic damper comprises a valve housing comprising an inlet chamber and an outlet chamber. A valve seat is arranged between the inlet chamber and the outlet chamber. A valve element having a cylindrical first portion is slidably received in a cylindrical bore of the valve housing. A second portion of the valve element has a valve surface for selectively engaging and disengaging the valve seat to allow passage of hydraulic fluid between the inlet chamber and the outlet chamber. A spring element is mounted within the valve housing for biasing the valve element into engagement with the valve seat.

Abstract: A servo valve comprising first and second nozzles and first and second piezoelectric actuators arranged to control fluid flow through the first and second nozzles respectively. A first fluid flow path is defined between the first nozzle and the first piezoelectric actuator and a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator. The first and second piezoelectric actuators are arranged such that applying a voltage to the first and second piezoelectric actuators causes a change in dimension thereof, which acts to open or restrict said first and second fluid flow paths respectively.

Abstract: A check valve including a valve housing defining a pair of valve openings; a pair of flappers pivotably mounted for rotation relative to the housing between an open position in which they permit fluid flow through the respective valve openings and a closed position in which they prevent fluid flow through the valve openings; and a stop element arranged such that the flappers will contact the stop element in their open positions. Each flapper includes a primary flapper element pivotally mounted to a hinge pin that extends across the valve, and a secondary flapper element. The primary flapper element further includes at least one flapper opening formed therethrough. The secondary flapper element is pivotally mounted such that it may rotate relative to the primary flapper element for opening and closing the at least one flapper opening in the primary flapper element.

Abstract: 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.