Abstract: A method for determining the status of a plurality of in a circuit, each switch having first switching arrangement for controlling the supply of a wetting current to the respective switch, and a second switching arrangement, whereby closure of the second switching arrangement enables the status of the respective switch to be determined, the method including the steps of closing the first switching arrangement associated with each of the switches so as to supply a wetting current to each of the switches and, when each one of the first switching arrangements is closed, closing the second switching arrangement associated with the same switch in order to determine the switch status. The invention also relates to an apparatus for determining the status of a plurality of switches.

Abstract: A vehicle braking system of the type in which a stored volume of fluid is used to apply the wheel brakes of the vehicle under the control of an electronic unit, the stored volume being held in an accumulator arranged to be replenished by pumping additional working fluid using a pump driven by an electric motor. The speed of the pump electric motor is arranged to be controlled in dependence upon whether or not any vehicle dynamic intervention, such as ABS, TC and VSC, is active. If it is deduced that one or more vehicle dynamic functions is active, then the pump is arranged to be run at high/full, and relatively noisy, speed, but if it is concluded that only base braking is being applied with no vehicle dynamic function being active, then the pump is arranged to be operated at a relative slower and hence quieter speed.

Abstract: A monitoring apparatus for monitoring operation of a no-back device of an actuator assembly driven by a motor, the apparatus comprising sensor device operable to sense an operating parameter of the motor for determining when the motor's output drive is in a direction opposite to a selected direction of motor output drive.

Abstract: A fuel control system for an engine, laving a pup operable to supply an output flow of fuel, engine fuel flow regulation means operable to regulate the pump output flow, and pump control means operable to vary an output rate of the pump according to an operational condition of the engine fuel flow regulation means.

Abstract: A contactor includes a switching circuit for switching a load between one or more electrical supplies, a current detector for detecting the current flowing through the load, a trip circuit for tripping the current after an interval of time which depends upon how much the current flowing through the load exceeds a predetermined amount, and a pre-trip circuit for providing an indication during said time interval that the current exceeds said predetermined amount for providing ‘pre-trip’ or ‘near-trip’ information.

Abstract: An actuator comprising, a first, rotatable member arranged to be driven by a motor, a sleeve, said first member cooperating with said sleeve such that rotation of the first member at a given speed relative to said sleeve causes the sleeve to be translated axially at a first speed through a predetermined distance, stop means limiting axial translation of the sleeve reative to the first member whereafter during continued rotation of the first member the sleeve rotates with the first member, a second, non-rotatable, member, said sleeve cooperating with said second member whereby rotation of the sleeve at said given speed causes axial translation of the second member relative to said sleeve at a second speed and, a brake arrangement applying a braking force to the sleeve, the braking force resisting rotation of the sleeve but not significantly affecting translation of the sleeve.

Abstract: Disclosed is a control system for a variable frequency generator including a main stator winding for providing a generator output, excited by a main rotor winding, and a main exciter rotor winding for energizing the main rotor winding, excited by a main exciter field winding. The control system includes: a plurality of inputs adapted to receive respective signals corresponding to respective generator operating parameters; an output adapted to drive the main exciter field winding; and a plurality of negative feedback loops between the output and the inputs. Each loop includes a respective stability compensation network operable to process a feedback signal corresponding to one of the generator operating parameters.

Abstract: In a solenoid-controlled valve assembly a biasing means (21) is adapted to apply a resisting force to a spool (22) in a direction opposite to the direction substantially of a force applied by an armature (14), and engagement between at least one of the spool and the biasing means and the spool and the armature is through an engagement means defining a single point of contact. The spool (22) may be provided with at least one land adapted to connect and disconnect two flow passages (6, 8), and the first ends of the two passages are spaced apart in a direction parallel to the axis of the bore by a smaller distance than the spacing between the second ends of the passages.

Abstract: An apparatus for supplying and controlling electrical power having a power source for supplying electrical power to a primary load and a secondary load, a capacitor connected to an input to the secondary load and control means operable to cause an operating condition of the apparatus to temporarily change from, a operating condition in which power from the power source is supplied to the primary and secondary loads to an alternative operating condition in which power from the power source is supplied to the primary load but is supplied to the secondary load thereby increasing the minimum voltage the capacitor can maintain at the input to the secondary load.

Abstract: An aero-engine is provided with an integrated switched reluctance generator permanently connected to the low speed spool of the engine such that “windmilling” of the engine enables the generator to be turned if the engine suffers a flame out. The generator is driven by a step up gearbox so as to provide reasonable electrical output, say 25 kW, during flameout whilst keeping the generator weight down.

Abstract: A skew detection system for use in sensing the occurrence of a skew condition in a system having a plurality of control surfaces located adjacent one another and which, in use, are driven to move simultaneously and at the same speed as one another, the skew detection system comprising a detector arrangement extending over and movable with the surfaces, between a first location on one of the surfaces and a second location on another of the surfaces, at least part of the detector arrangement being arranged to move in the event that one or more of the surfaces becomes skewed, and a sensor arranged to permit a change in the position of the said part of the detector arrangement to be detected. In one embodiment, a skew condition can be sensed using two sensors.

Abstract: A fuel system, for use in supplying pressurised fuel to a combustion space, comprises a fuel source of pressurised fuel and a fluid pressure actuable valve controlling communication between the fuel source and an injection nozzle. The fuel system further comprises a second source of control fluid under pressure and a control valve controlling the application of control fluid under pressure to the fluid pressure actuable valve to control operation of the fluid pressure actuable valve. The invention also relates to a fuel injector for use in such a fuel system, the fuel injector comprising the injection nozzle, the fluid pressure actuable valve and the control valve.

Abstract: A fuel system comprising a low pressure fuel pump having an outlet which is connected to an inlet of a high pressure pump arranged, in use, to supply fuel to an engine. The fuel system her comprises at least one actuator controlled by a servo-valve, wherein the servo-valve has a high pressure connection connected to the high pressure side of the high pressure pump and a low pressure connection connected upstream of the outlet of the low pressure pump.

Abstract: An actuator system comprising a rotary actuator having an input member, a first output and a second output, the first and second outputs being arranged to move at substantially the same regular speed upon rotation of the input member, a drive shaft coupled to the input, and first and second output shafts coupled, respectively, to the first and second outputs. The invention also relates to a rotary actuator for use in the actuator system.

Abstract: In an electro-hydraulic braking system a housing is provided having at least three discrete housing portions (1, 2, 3), a first portion being adapted to contain electrical drive circuitry for said at least one actuator, the second portion being adapted to contain hydraulic flow passages to and from the electrically operated actuator, and the third portion being adapted to house one or more pressure sensors. On assembly of the housing, electrical contacts from the one or more pressure sensors in the third portion provide a connection between the one or more pressure sensors and the electrical circuitry contained in the first portion, and hydraulic passages extending from the pressure sensors in the third portion provide a connection between one or more pressure sensors and fluid passages in the second portion.

Abstract: A printed circuit device comprising, a printed circuit board having an electrically conductive heat plane associated with a surface thereof, the circuit board having an opening formed therein which exposes a ground layer or track of the circuit board, a wall defining the opening being provided with an electrically conductive coating which is electrically connected to the ground layer or track, the heat plane being provided with a cut-out defining a projection which is bent to extend into the opening, the projection being secured to said coating electrically to connect the coating and the ground layer or track to the heat plane. The invention also resides in a method of manufacturing a printed circuit device and in a heat plane for use in such a device.

Abstract: A fuel control system for an engine, having a pump operable to supply an output flow of fuel, engine fuel flow regulation means operable to regulate the pump output flow, and pump control means operable to vary an output rate of the pump according to an operational condition of the engine fuel flow regulation means.

Abstract: An actuator having a piston member slideable within a cylinder, the piston member defining with the cylinder a first chamber and a second chamber, the effective cross-sectional of the piston member exposed to the fluid pressure within the first chamber being greater than that exposed to the fluid pressure within the second chamber. The actuator further has first and second ports through which fluid can be supplied to the first and second chambers, respectively, and a third port located intermediate the first and second ports. The piston member and the third port are cooperable to throttle the rate at which fluid is able to escape from the first and second chambers through the third port, in use.

Abstract: A cruise controller (2) with a set speed and/or acceleration limit reduction facility is provided. If the controlled vehicle becomes slowed due to the presence of a slower moving vehicle in front of it, the set speed and/or acceleration limit is reduced in order to prevent rapid acceleration from occurring if the target vehicle suddenly moves out of the way.

Abstract: Solid state switching devices, such as power IGBT's, are used to switch a load from one AC generator to another. The switching is controlled to occur only when the phase and voltage of the two generator outputs are within acceptable limited, thus minimising voltage and current transients.