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 piezoelectric actuator configured to vary the flow of fluid to respective ends of the valve spool in response to the control signal.

A valve assembly that provides reliable opening and closing valves at specified times despite changing performance characteristics of the valve is disclosed. The valve assembly includes a controllable valve selectively actuatable to control flow of a fluid therethrough, with the controllable valve having a variable valve open/close response time. The valve assembly also includes a plurality of sensors configured to measure current operational parameters of the controllable valve and/or the fluid and a valve controller programmed to process valve timing control instructions generated by an external source, process inputs from the plurality of sensors regarding the measured operational parameters of the controllable valve and/or the fluid, and provide an actuation signal to the controllable valve based on the valve timing control instructions and the inputs from the plurality of sensors, so as to control a timing of an actuation of the controllable valve.

A servo valve comprises a valve housing, a cavity formed in the valve housing and a member disposed in the cavity and axially-moveable therein. The servo valve further comprises a piezoelectric actuator configured to axially move the member, relative to the valve housing, between first and second axial positions.

A servo valve comprising: a fluid transfer valve assembly comprising a supply port and a control port (P.sub.A, P.sub.B); 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

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 pressure control valve has: a passageway having a flow opening; an member displaceable relative to the opening for obstructing the opening by differing amounts; a piezo actuator; and a linkage mechanism adapted to amplify a dimensional change in the piezo actuator and to use the amplified dimensional change to displace the member relative to the opening, wherein the linkage mechanism comprises a frame attached to a wall and fixed at a first end in relation to the passageway, a portion of the frame moveable in a first direction while being substantially restrained in a second direction orthogonal to the first direction, the piezo actuator extending between the wall and the movable portion such that an expansion of the piezo actuator results in movement of the movable portion in the first direction by an amount greater than the expansion of the piezo actuator, the moveable portion connected to the member.

In accordance with at least one aspect of this disclosure, a system can include, a moveable component configured to move between one or more positions, a biasing member operatively connected on a first side to bias the moveable component to a respective one of the one or more positions, and a preload member operatively connected to provide a force to a second side of the biasing member. An actuator can be operatively connected to move the preload member in response to a signal from a controller.

In an optical sorter that includes an optical detection unit to detect a to-be-sorted material at a detection position, a determining unit to determine a to-be-sorted material to be removed, based on a detection result by the optical detection unit, and an air-jetting unit to blow off and remove the to-be-sorted material to be removed using jet air of a compressed gas, based on a determination result by the determining unit, the air-jetting unit includes a piezoelectric valve to perform valve opening and closing by driving a valve disc utilizing displacement of a piezoelectric element, and a valve driving unit to apply a drive voltage to the piezoelectric element, and the valve driving unit controls the drive voltage applied to the piezoelectric element in accordance with the to-be-sorted material to be removed to thus control a jet-air pressure of the compressed gas for removing the to-be-sorted material.

A servo valve including a piezo-electric actuator, a flexible linkage, and control valves. The piezo-electric actuator is actuatable along a piezo stack axis. The flexible linkage is coupled to the piezo-electric actuator at opposite axial ends of the actuator. Control valves are disposed at laterally opposite sides of the piezo stack axis and include respective valve stems coupled to the flexible linkage. The flexible linkage may be configured to transfer motion of the piezo-electric actuator along the piezo stack axis to a motion of the valve stems along an amplification axis that is transverse to the piezo stack axis to open and close the control valves. A symmetric actuation element incorporating the piezo-electric actuator, or a different actuator, may have first and second chambers at laterally opposite sides thereof, and be electrically actuatable along an actuation axis to open and close supply and return ports to control fluid communication with respective first and second work ports of respective first and second chambers.

A linear valve drive for connection to a valve body which has a valve seat is described, wherein said linear valve drive comprises a drive housing, a valve closure element and a piezoelectric actuator which is arranged within said drive housing. Said valve closure element is displaceable in the axial direction between an open position and a closed position by means of said piezoelectric actuator and an interposed actuating device. Said piezoelectric actuator is supported on said actuating device via its side directed towards the valve closure element. Said linear valve drive comprises an adjusting device which is configured such that an idle stroke of said linear valve drive is adjustable. A valve is also described.