A positioner according to the present invention includes: an electro-pneumatic converter that converts an input electric signal into a pneumatic signal and controls the valve opening of a regulating valve by driving an operational unit in accordance with the pneumatic signal; an operating-point searching unit that changes the electric signal by performing open loop control to search for an operating point indicating a target valve-opening value of the regulating valve when an output air pressure of the pneumatic signal starts to change; and a PST executing unit that executes a PST on the regulating valve by using the operating point found by the operating-point searching unit. The operating-point searching unit sets the operating point based on a value of the electric signal when the output air pressure matches a first reference value.

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 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.

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.

A system is described for positioning and locking in place a nozzle within a cylindrical bore of a body, and a method for positioning and locking in place a nozzle within a cylindrical bore of a body is also described. The system has a nozzle having a tubular shape extending between a first end and a second end with an outer cylindrical surface and an inner surface, said inner surface comprising a thread. The system also has a locking member provided within said nozzle and comprising an outer circumferential surface having a thread that corresponds to the thread of the inner surface of the nozzle. The system also has means for providing torque to said locking member to screw said locking member into and within said nozzle via said threaded surfaces to thereby create a press-fit between said outer cylindrical surface and an inner surface of said cylindrical bore.

A system is described for positioning and locking in place a nozzle within a cylindrical bore of a body, and a method for positioning and locking in place a nozzle within a cylindrical bore of a body is also described. The system has a nozzle having a tubular shape extending between a first end and a second end with an outer cylindrical surface and an inner surface, said inner surface comprising a thread. The system also has a locking member provided within said nozzle and comprising an outer circumferential surface having a thread that corresponds to the thread of the inner surface of the nozzle. The system also has means for providing torque to said locking member to screw said locking member into and within said nozzle via said threaded surfaces to thereby create a press-fit between said outer cylindrical surface and an inner surface of said cylindrical bore.

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 axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The spool includes a tubular body defining a path for fluid flow, the tubular body closed at each end by a respective end cap having openings via which, in use, fluid enters the interior of the spool. The end caps extend within the tubular body at least to an extent that they overlap the openings, and wherein the end caps are provided with filter means for filtering the fluid from the openings as it enters the spool.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port and a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal. The servovalve also includes 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 comprises a jet pipe a connector header fluidly connecting the jet pipe to a nozzle. The spool has one or more openings 28 is provided in the spool such that fluid from the supply port flows into the interior of the spool and into the jet pipe.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port and a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal. The servovalve also includes 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 comprises a jet pipe a connector header fluidly connecting the jet pipe to a nozzle. The spool has one or more openings 28 is provided in the spool such that fluid from the supply port flows into the interior of the spool and into the jet pipe.

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.