A fluid system has a fluid actuator that receives a fluid to cause movement of a component. A valve selectively controls the flow of fluid to the fluid actuator. A motor for the valve is provided with an electric voltage or current. A control applies a pulse width modulation variation to the supplied voltage or current. The control is operable to vary the pulse width modulation of the voltage or the current based upon conditions of the system. A mechanical system and a method are also disclosed.

There is disclosed a flow control nozzle for controlling the flow of an incompressible fluid, the flow control nozzle having a flow area and comprising a deformable element comprising a shaped memory alloy (SMA) material wherein within a range of operating temperatures the SMA material is configured to reduce the flow area of the flow control nozzle as the operating temperature increases. The flow control nozzle is thus able to dynamically compensate for changes in operating temperature in order to maintain a constant flow.

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 spool assembly for a second stage of a servo valve comprises a spool having an axis (L) and an opening for a feedback member provided in a central region of the spool extending perpendicular to the axis. An adjustable joint is provided within the spool for securing a feedback member relative to the spool, comprising first and second jaw arms being displaceable relative to each other along the axis of the spool. The jaw arms have opposing clamping surfaces, wherein the clamping surfaces are arranged to be drawn towards each other as the jaw arms are drawn away from each other, such that a feedback member can be clamped between the opposed clamping surfaces of the jaw arms and thereby secured relative to 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.

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.

Servo-valve that drives an actuator by using a fluid. The servo-valve includes a nozzle having a discharge edge forming an outline of a discharge port from which the fluid is discharged and a tapered inner wall growing narrower toward the discharge edge, and a receiver that is provided with a flow path into which the fluid discharged from the discharge port flows. The nozzle is displaced in a direction different from the fluid discharge direction. The flow path extension direction is inclined with respect to a direction orthogonal to an inflow surface facing the nozzle by an angle . A taper angle determined by the tapered inner wall is larger than twice the angle . With such a configuration, the component of flow force exerted from the fluid on the tapered inner wall decreases. Since the nozzle can be quickly displaced, response speed of the actuator is improved.

An electrohydraulic servo valve (EHSV) includes a housing assembly, a spool valve, an armature, a control mechanism, and a feedback spring. The spool valve is movably disposed within the housing assembly. The armature is rotationally mounted on the housing assembly. The control mechanism is coupled to the armature and is rotatable therewith. The feedback spring is coupled between the control mechanism and the spool valve, and includes a helical coil that is disposed on and engages the control mechanism, and a cantilever portion that extends from the helical portion to a terminus that engages the spool valve.

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 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.