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 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 torque motor for a servovalve, said torque motor comprising a set of pole pieces comprising a first pole piece and a second pole piece. An armature is also provided between the first pole piece and the second pole piece, said armature configured to provide air gaps (AG1-AG4) between the armature and the first pole piece, and the armature and the second pole piece. The armature is configured to rotate about a centre point (CP). The set of pole pieces is also adapted to rotate around the centre point (CP) such that the air gaps (AG1-AG4) can be adjusted.

There is provided a pole-piece for a torque motor, the pole-piece comprising a first section formed separate from a second section, wherein the first section is held in position with respect to the second section using one or more rigid members.

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. The jet pipe terminates at one end in a nozzle and at the other end being in fluid flow engagement with and fixedly connected to a fluid supply torsion tube arranged to receive fluid from a fluid source. Movement of the valve spool is caused by fluid flowing from the nozzle to engage with the valve 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.

There is provided a method of manufacturing a torsion spring, comprising providing a section of sheet metal, and forming the torsion spring from the section of sheet metal.

In a closed loop control method for an electropneumatic field device, an electronic target value input of a command variable corresponding to a target value of a control center is received by the open loop and/or closed loop control electronics, an electronic output for a manipulating variable to pilot the electropneumatic converter is generated by the open loop and/or closed loop control electronics; and, in a predetermined operating condition of the field device, the manipulating variable is determined by a closed loop control algorithm based on the command variable and on another controlled variable different from an actual control member position measurement value.

The disclosure discloses a servo-valve that controls a fluid discharged from a discharge port of a nozzle by displacing the nozzle and drives an actuator. The servo-valve includes a receiver that includes an inflow surface provided with a first inflow port and a second inflow port into which the fluid discharged from the discharge port flows. The nozzle includes a force generation portion that includes an end surface provided with the discharge port and an outer circumferential surface formed in the periphery of the end surface. When the nozzle is displaced from a neutral position toward the first inflow port, the fluid inside the second inflow port is blown out toward the nozzle. The force generation portion collides with the fluid blown out from the second inflow port and causes an assisting force in a direction matching a nozzle displacement direction toward the first inflow port. The nozzle easily moves by the assisting force generated in the force generation portion and thus a response speed is improved.

A torque motor assembly comprising two or more pole piece pairs, each pair comprising two opposing pole pieces each having an end facing an end of the opposite pole piece, the ends separated by a gap; and a magnetic plate extending between the pole piece pairs and located in the gap, the magnetic plate having surface portions facing the respective pole piece ends; wherein the surface portions of the magnetic plate and the respective pole piece ends are non-parallel with respect to each other.