Abstract: An active electromagnetic interference filter comprising an adjustable shunt impedance circuit, the adjustable shunt impedance circuit comprising a noise sensing branch that senses input noise and provides a noise voltage representative of the sensed noise, and an operational amplifier stage configured to generate, at an injection branch, an injection current based on the noise voltage.

Abstract: There is provided herein a method of advancing phase of a DQ reference frame in a Field Oriented Control, FOC, algorithm for a permanent magnet motor. The method comprises: monitoring a component of the stator voltage demand of the permanent magnet motor, when the component of the stator voltage demand surpasses a threshold, calculating a phase advance angle, ?adv, based on a gain multiplied by the difference between the component of stator voltage demand and the threshold; and advancing phase of the DQ reference frame in the FOC algorithm based on the calculated phase advance angle, up to a maximum phase advance angle when motor speed is positive, or down to a minimum phase angle when motor speed is negative.

Abstract: A positioning arrangement for positioning a rotor relative to a shaft includes a collar provided with a formation cooperable with a corresponding formation provided upon the shaft to resist relative angular movement between the collar and the shaft, the collar being provided with an external, generally axially extending rib cooperable with a part of the rotor to deform the said part of the rotor to resist relative rotation between the collar and the rotor.

Abstract: A fuel staging system comprises a splitter valve arranged to split an input fuel stream into a pilot fuel stream and a main fuel stream, the splitter valve comprising a spool slidable within a bore, the spool and bore together defining first and second control chambers, the fluid pressures in which determine the position occupied by the spool, the system further comprising a control line which, in use, controls fuel delivery through a plurality of main burners, the fluid pressure in the control line being a combination of the fluid pressures in the first and second control chambers.

Abstract: A fuel system comprises a first, variable displacement fuel pump operable to supply fuel through a metering valve to an engine, a control servo operable to control the operation of the first pump, a pressure drop control valve (PDCV) responsive to a pressure drop across the metering valve, a second fuel pump, and a spill valve movable between an open position in which substantially all of the fuel supplied by the second fuel pump is returned to an inlet side thereof, and a closed position, or partially closed position, wherein a proportion of the fuel supplied by the second pump is delivered to the engine.

Abstract: A rectifier comprising an electrically conductive support 32, a first plurality of rectifier components 24 carried by the support 32 and having their anodes connected to a first bus bar 26, a second plurality of rectifier components 28 carried by the support 32 and having their cathodes connected to a second bus bar 30, the cathode of each of the first rectifier components 24 being connected to the anode of an associated one of the second rectifier components 28, and first and second resistance paths 40, 42 between the first and second bus bars 26, 30 and the support 32.

Abstract: A system comprises a pressure raising valve having a valve member movable within a bore between a closed position and an open position in which fuel supplied to the pressure raising valve from a metering valve, in use, is delivered to an engine manifold, the valve member being urged towards its closed position by the fuel pressure within a control chamber, the pressure raising valve including a low pressure port which communicates with the control chamber when the valve member is in its closed position, the valve member closing the low pressure port upon movement thereof away from its closed position beyond a predetermined distance.

Abstract: A rotary electric machine comprises a rotor rotatable within a stator assembly, the stator assembly comprising a stator body defining a plurality of stator slots accommodating electrical conductors, a slot liner being provided within each slot to provide electrical insulation between the stator body and the electrical conductors, wherein each slot liner protrudes from an end of the stator slot and carries an armor element to protect the slot liner and associated conductors from erosion while permitting efficient cooling.

Abstract: A fuel system is described that comprises a pressure raising and shut-off valve (PRSOV), and a control valve arrangement operable to control a fuel pressure applied to a part of the PRSOV urging the PRSOV towards a closed position, wherein the control valve arrangement is supplied with fuel at a pressure controlled by a variable fluid pressure potentiometer network including a variable flow restrictor which is variable in response to changes in the position occupied by the PRSOV.

Abstract: A method is described for controlling the operation of a metering valve driven by a stepper motor, a position sensor normally providing position information to allow control over the metering valve in a closed loop manner. The method comprises the steps of: performing a calibration operation to derive a relationship between stepper motor position and metering valve position; controlling the operation of the metering valve in a closed loop manner; and controlling the operation of the metering valve in an open loop manner in the event that the position sensor output is thought to be unreliable; wherein, when operating in the open loop manner, the metering valve is moved to a desired angular position by using the relationship derived in the calibration operation to determine the stepper motor position associated with the desired metering valve position and moving the stepper motor to the determined stepper motor position.

Abstract: A rectifier comprising an electrically conductive support 32, a first plurality of rectifier components 24 carried by the support 32 and having their anodes connected to a first bus bar 26, a second plurality of rectifier components 28 carried by the support 32 and having their cathodes connected to a second bus bar 30, the cathode of each of the first rectifier components 24 being connected to the anode of an associated one of the second rectifier components 28, and first and second resistance paths 40, 42 between the first and second bus bars 26. 30 and the support 32.

Abstract: A drive arrangement comprising a drive shaft, a clutch arrangement operable, upon axial movement of the drive shaft occurring, to interrupt drive to the drive shaft, an axially movable interrupt shaft, a gear arrangement whereby the interrupt shaft is driven for rotation by the drive shaft at a speed slower than the rotary speed of the drive shaft, a disconnect device operable to cause axial movement of the interrupt shaft, and a transmission device for transmitting axial movement of the interrupt shaft to the drive shaft.

Abstract: A drive disconnect device for releasably connecting an electrical generator to a drive shaft, the drive disconnect device comprising an output shaft and at least one drive transfer element movable from a first position where it drivingly connects the drive shaft and the output shaft to a second position where the driving connection is removed, wherein operation of the disconnect device causes the electrical generator to become electrically isolated or excitation for the generator to be inhibited.

Abstract: A fuel pumping system comprises a high pressure pump having a drive input, a drive gear driven for rotation, in use, by the drive input, an idler gear driven by the drive gear, and an output gear driven by the idler gear, wherein the output gear is arranged to drive a rotor of an electrical generator and the idler gear is arranged to drive a rotor of a low pressure pump.

Abstract: A fuel system comprises a pressure raising valve operable to control communication between a fuel delivery line and an engine manifold line, and an ecology valve comprising a piston movable within a bore, the piston and bore together defining a control chamber and an ecology chamber, the ecology chamber communicating with the engine manifold line, the pressure within the control chamber being controllable to control the position occupied by the piston, the ecology valve further comprising seal means whereby, when the piston occupies a first position in which it engages the seal means, only a first, relatively small, effective area of the piston is exposed to a fuel pressure within the engine manifold line, a second, larger, effective area being exposed to the fuel pressure within the engine manifold line when the piston occupies a position in which it does not engage the seal. An ecology valve for use in the fuel system is also described.

Abstract: A rotor assembly comprises a rotor body defining a pole, a winding encircling the pole, a compression member located radially inwards of the winding, and compression means located between the compression member and the rotor body and operable to urge the compression member in an outward direction to apply a compressive load to the winding. A method of assembly of the rotor is also disclosed.

Abstract: A piezoelectric perovskite mixed oxide compound has the general formula (BiFeO3)x—(PbTiO3)1-x and contains up to 5 at % lanthanum or other rare earth substitution, in which x has a value in the range 0.5 to 0.9. Such compounds are capable of withstanding gas turbine operating temperatures and are suitable for use in sensing and actuation functions in aerospace and other applications.

Abstract: A fuel control system for a gas turbine engine reheat system has a plurality of fuel metering devices for controlling fuel flow to respective ones of the reheat burners, and a plurality of throttle valves in series with the respective metering devices. One of the throttle valves regulates a pressure difference across its associated metering device and the remaining throttle valves maintain the pressure difference across their respective metering devices equal to that controlled by the aforesaid one throttle valve. The system may include a fuel supply valve which is responsive to a pressure signal controlled by two of the metering devices so that fuel supply from a pump is provided only when both of the two metering devices are open. The pump may include a delivery pressure regulating arrangement responsive to pump delivery pressure and to the highest of the pressures downstream of the metering devices, for regulating pump delivery pressure so as to maintain the metering pressure differences constant.

Abstract: A method is described for controlling the operation of a metering valve driven by a stepper motor, a position sensor normally providing position information to allow control over the metering valve in a closed loop manner. The method comprises the steps of: performing a calibration operation to derive a relationship between stepper motor position and metering valve position; controlling the operation of the metering valve in a closed loop manner; and controlling the operation of the metering valve in an open loop manner in the event that the position sensor output is thought to be unreliable; wherein, when operating in the open loop manner, the metering valve is moved to a desired angular position by using the relationship derived in the calibration operation to determine the stepper motor position associated with the desired metering valve position and moving the stepper motor to the determined stepper motor position.

Abstract: A rotary metering valve arrangement comprises a rotary metering valve arranged to control the supply of fuel to a Pressure Raising and Shut-Off Valve (PRSOV), the metering valve comprising a valve plate provided with first and second latching ports and an angularly movable valve element provided with a recess registrable, in use, with the first and second latching ports to control communication therebetween, the PRSOV comprising a valve member slidable within a bore provided with third and fourth latching ports the valve member being provided with a recess registrable, in use, with the third and fourth latching ports to control communication therebetween, the second and third latching ports communicating with one another.