An electropneumatic solenoid valve for a pneumatically-actuated field device can include air channels, a flapper valve member, an electromagnetic controller, and a spring. An air supply channel, air dispensing channel and air exhaust channel can be mound into an air chamber. The flapper valve member can include a closure element arranged on an axial control direction and be engageable with a delimitation interior wall mouth of one of the air channels such that the flapper valve member is arranged with a circumferential axial distance to the delimitation interior wall. The electromagnetic controller can displace the flapper valve member in the axial control direction to ventilate/exhaust the air dispensing channel. The spring can bias the flapper valve member into a closed position to close closing the one of the air channels. The flapper valve member can be float-mounted in an unguided configuration except for spring within the air chamber.

A system uses a two-stage electrohydraulic servo valve that includes an additional control port that commands a fail-fixed valve to lock the position of a device in the last commanded position. The additional port is modulated by an existing land on the EHSV valve element, adding little to no complexity. Major technical benefits of the disclosed system are that it adds little to no cost, complexity, size, or weight the device being controlled. The disclosed configuration allows for the use of a relatively small and simple fail-fixed valve, and the control ports on the controlled device keep “drift” to a minimum, when transitioning between normal operating mode and fail-fixed operating mode.

A valve controller configured to operate on a Foundation Fieldbus Network and including a spool valve movable between at least an opening position and a closing position, and a flapper nozzle pilot valve arranged to move the spool between the opening position and the closing position.

A nozzle with changeable press fit and a method for calibrating a nozzle is described. The nozzle may be used in a nozzle/flapper type servovalve. The method comprises the steps of providing a nozzle within a cylindrical body defining a cylindrical bore, the nozzle having a tubular shape with an outer cylindrical surface and an inner radial surface., the method further comprises the steps of positioning a first, tubular locking member within the nozzle, and axially moving the first, tubular locking member within the nozzle. The first tubular locking member is configured to cause the nozzle to become positionally fixed at a selected position within the bore in response to the first, tubular locking member being axially moved relative to the nozzle. A nozzle positioning system is also described herein.

The present disclosure provides a heat exchanger system for a servovalve, comprising a base comprising a supply port in fluid communication with a return port, a first passage for fluid connection to a source of cooling fluid, and a second passage in fluid communication with the return port. The system further comprises one or more pipes located over a surface of the base, the one or more pipes fluidly connected between the first passage and the second passage, such that in use cooling fluid may flow from the first passage to the second passage via the network of pipes.

A flapper for use in a servovalve is described, the flapper comprising a first material and a second material, the first material having a first coefficient of thermal expansion and the second material having a second coefficient of thermal expansion and wherein the first and second coefficients of thermal expansion are different to each other. An armature/flapper assembly is also described, which comprises this flapper as well as a plate and a torsion bridge. A method of compensating for alteration of the null of a servovalve due to temperature changes in a servovalve is also described.

A nozzle of or for a servo valve comprises a nozzle element having a fluid outlet at a first axial end and a tubular body extending from the first end to an opposed, second axial end. The nozzle further comprises a plug element mounted in and closing the second axial end of the tubular body, thereby defining an internal cavity within the tubular body. One or more openings are formed through the tubular body to fluidly communicate with the internal cavity. A filter may be mounted across the internal cavity at a position axially intermediate the openings and the fluid outlet.

A hydraulic stage includes a hydraulic element located between and sealing a first and second chamber, wherein the first chamber comprises at least one aperture through which fluid is arranged to flow into or out of the first chamber; and at least one piezoelectric element which is positioned adjacent to the at least one aperture and is arranged to deform in response to an applied potential difference such that it blocks or obstructs the at least one aperture to a varying degree according to the level of deformation, so as to control fluid flow into or out of the first chamber. The level of deformation of the piezoelectric element thus reduces or increases an effective size of the inlet or outlet aperture to which it is adjacent, restricting or permitting an increase in fluid flow accordingly.

An integral flapper and nozzle structure for a servo valve assembly whereby the flapper, orifices and nozzles are formed by sheets of metal formed into a single component.

Systems and methods are provided for controlling hydraulic valves. One embodiment is a method that includes blocking an orifice for a return line of a hydraulic valve via a flapper assembly, initiating a phase change in a Shape Memory Alloy (SMA) at the flapper assembly, and opening the orifice for the return line via the flapper assembly in response to the phase change.