Abstract: A generator controller for controlling a permanent magnet generator where each phase of the generator is connectable to a DC link via electrically controllable switches, the controller characterised by a data processor adapted to receive a measurement of generator current output and a demand current, and to form a current error between the demanded value and the measured generator current; derive a target voltage as a function of the current error; and form control signals for the electrically controllable switches as a function of the target voltage.

Abstract: A disconnect mechanism is provided which, upon a suitable trigger event, such as excess temperature causes a camming element 40 having a tapered head 52 to move under the urging of a compression spring 60 such that the tapered head 52 becomes trapped between a rotating element 32 and a support 42. This gives rise to frictional inter-engagement which prevents further rotation of the rotating element 32 and thereby locks the rotating machine against further rotation. This is turn causes the shear region to fail thereby drivingly disconnecting the machine from its prime mover.

Abstract: A fuel supply system for a gas turbine engine including first and second positive displacement pumps operated simultaneously to supply fuel under pressure from a low pressure source, a combining spill valve controlling the output flows from the first and second pumps to combine the outputs of the first and second pumps for supply to a metering valve of the system, or to spill some or all of the output of one or both pumps back to the low pressure supply, a pressure raising and shut off valve arrangement downstream of the metering valve for isolating the fuel system from an associated engine until the fuel pressure upstream of the pressure raising and shut off valve arrangement exceeds a predetermined pressure, and, a control system dependent upon the position of the combining spill valve for reducing said predetermined pressure at which said pressure raising and shut off valve arrangement opens.

Abstract: An aircraft gas turbine engine fuel metering unit incorporating a memory device for storing data relevant to that unit, and an electrical connection arrangement whereby data can be read from and/or written to said memory device by an associated electronic engine controller, said stored data including data relating to at least one of the performance, the identification, the health, and the service life of that fuel metering unit. The invention further resides in an aircraft gas turbine engine fuel supply system and a method of operating such a system.

Abstract: A drive disconnect device is provided in which a drive transfer element (12) is axially movable with respect to input and output shafts (2, 14) so as to selectively disconnect them. A collar (50) is disposed in spaced apart configuration around the drive transfer element so that they do not touch except when the disconnect device is operated to disconnect the drive. When the disconnect operation is initiated, force is provided from a resilient element (56) to move the drive transfer element.

Abstract: A pressure regulator includes a housing, a metering spool, a first pressure chamber at a reference pressure to which one end of the metering spool is exposed, a spring within the first pressure chamber acting against the one end of the metering spool, a second pressure chamber containing hydraulic fluid at the regulated pressure acting against the opposite end of the metering spool, wherein the position of the metering spool relative to the housing is a position of equilibrium that changes to maintain a predetermined pressure difference between the reference pressure and the regulated pressure. An abutment against which the opposite end of the spring reacts is provided and a third pressure chamber at a control pressure acts on the abutment, such that the control pressure can be changed to adjust the position of the abutment to change the pre-load of the spring to adjust the value the predetermined pressure difference.

Abstract: An AC to DC converter with harmonic suppression is provided. The harmonic suppression is provided by forcing an instantaneous current conflict between series connected rectifier bridges 54, 80, such that a voltage waveform at 6 times the AC supply frequency of the AC supply is automatically generated. This waveform is then injected via a injection circuit to give harmonic cancellation.

Abstract: A fuel control system for a staged combustion engine comprising, a fuel metering unit including a fuel metering valve having a fuel metering orifice the opening of which is varied to meter the flow of fuel through the metering valve in use, a fuel staging unit receiving fuel from the metering valve of the fuel metering unit and incorporating a staging valve for dividing the flow of fuel from the fuel metering unit to pilot burner and main burner output lines, a connection between a fuel pressure region of said fuel metering unit and a port of said staging valve, and, overthrust detection means causing said staging valve, in response to overthrust detection, to connect said port of said staging valve to low pressure, whereby to drain fuel under pressure from said pressure zone of said fuel metering unit to low pressure to limit or reduce the fuel supplied from the fuel metering unit to the fuel staging unit and thus to the engine in use.

Abstract: A fuel control system as claimed in claim 1 wherein, the pressure raising valve includes: a pressure raising valve member exposed to fuel pressure within a reference chamber, an inlet to which fuel at supply pressure is supplied, wherein the pressure raising valve member is movable against a force due to pressure within the reference chamber by means of fuel at supply pressure, an outlet through which fuel at delivery pressure is supplied to the engine, and feedback means for permitting fuel at delivery pressure to flow to the reference chamber. There is also disclosed a pressure raising valve for use in such a system.

Abstract: A generator controller (4) is provided which is able to detect and respond to failure of a generator output voltage sensor, whilst being able to distinguish voltage sensor failure from output voltage collapse due to the presence of an overload or short circuit condition. The presence of a voltage sensor failure is indicated by the measured output voltage being below a first voltage threshold whilst the output current is also below a current threshold.

Abstract: A fuel control system for controlling the supply of fuel to an engine, the control system comprising: pump means for providing a flow of fuel to said engine; first and second drive means for driving said pump means; and, control means for controlling said first and second drive means; wherein, said control means is arranged to control said first and second drive means such that in the event of failure of one of said first and second drive means, said pump means is driven by the other of said first and second drive means.

Abstract: A compensation circuit is provided for use in a drive arrangement for an isolation transformer in series with a capacitor. The compensation circuit applies a compensation voltage to the capacitor such that the voltage across the capacitor remains substantially invariant.

Abstract: An unpressurised aeronautical generator (2), is provided which includes a two stage oil pump (6) comprising a centrifugal pump (8) and a gerotor pump (26). The centrifugal punp draws oil through openings (18) in a manifold, pressurises it and supplies it to the gerotor pump. The gerotor pump then pumps the pressurised oil throughout the generator. A small gerotor pump is used, which is still sufficient to operate at low pressures and high altitudes.

Abstract: A rotor assembly for a dynamo electric machine, the rotor assembly comprising a rotor core incorporating radially extending rotor poles, rotor windings encircling respective rotor poles, circumferentially extending pole tips at the outer end of each pole respectively, said tips overlying the rotor winding encircling the respective pole, a plurality of rotor slot closure members, each closure member spanning the gap between a pair of adjacent poles, and including lateral flanges interposed between the respective rotor windings and the associated pole tips, a spacer member positioned beneath each closure member and engaging the radially extending faces of the adjacent windings, and, a locking wedge assembly comprising a pair of locking wedges extending axially of the rotor assembly between each closure member and the associated spacer, the locking wedges extending with their tapers in opposite directions so that moving the wedges longitudinally towards one another increases the radial dimension of the combinati

Abstract: An AC to DC converter with harmonic suppression is provided. The harmonic suppression is provided by forcing an instantaneous current conflict between series connected rectifier bridges 54, 80, such that a voltage waveform at 6 times the AC supply frequency of the AC supply is automatically generated. This waveform is then injected via a injection circuit to give harmonic cancellation.

Abstract: A drive disconnect device is provided in which a drive transfer element (12) is axially movable with respect to input and output shafts (2, 14) so as to selectively disconnect them. A collar (50) is disposed in spaced apart configuration around the drive transfer element so that they do not touch except when the disconnect device is operated to disconnect the drive. When the disconnect operation is initiated, force is provided from a resilient element (56) to move the drive transfer element.

Abstract: According to the present invention there is provided a fuel injection system for a combustion engine, comprising: a fuel metering unit for providing a metered supply of pressurized fuel, at least one first fuel injector, at least one second fuel injector, a fuel supply passage arrangement for supplying fuel from the fuel metering unit to the at least one first fuel injector and the at least one second fuel injector. The fuel supply passage arrangement including a first valve for controlling the flow of fuel from the fuel metering unit to the at least one second fuel injector. The first valve having a fuel inlet communicating with the fuel metering unit, a fuel supply outlet communicating with the at least one second injector.

Abstract: A fuel system for a gas turbine engine having a main burner fuel supply line and a pilot burner fuel supply line, a high pressure pump supplying fuel to the main and pilot burner supply lines in use, a throttle valve controlling the flow of fuel in the main burner supply line, a metering valve controlling the flow of fuel in the pilot burner supply line, and a pressure raising valve between the pilot burners and the metering valve, the pressure raising valve serving to maintain the upstream fuel pressure to a pre-determined amount in excess of the pressure of fuel supplied from the throttle valve to the main burners.

Abstract: A data flow controller comprises two buffers 20 and 22 and a control element 24 for checking for predefined temporal constraints between items of data and for only allowing items of data to be transferred from the first buffer to the second buffer when the data items satisfy the temporal constraints.

Abstract: A switching circuit controls at least one semiconductor switch TR1 using drive signals generated from logic circuitry 4 that generates complementary drive signals on an upper and lower drive path. Validation circuitry is provided between the logic circuitry and the semiconductor switch that inhibits any uncontrolled switching of the semiconductor switch TR1 due to noise, such as lightning strike, appearing at the load.