Abstract: A variable displacement vane pump includes a pump housing having a cylindrical interior chamber, a cylindrical rotor member mounted for rotational movement within the interior chamber of the pump housing, a cam member mounted for pivotal movement within the interior chamber of the pump housing about a fulcrum aligned with the vertical centerline of the interior chamber, the cam member defining a cam body having a circular bore extending therethrough for receiving the rotor member, the cam body having lateral sealing lands formed thereon, the sealing lands having arcuate sealing surfaces defining segments of a cam arc through which the cam member pivots, and static cam seals supported within the interior chamber of the pump housing and oriented on each end of a chord of the cam arc, each cam seal biased into a continuous contact position with an adjacent sealing surface of the cam member.

Abstract: A fuel metering unit including a pump having a rotor with a plurality of slots. The pump also includes a pivotally movable cam ring coaxially arranged with respect to the rotor. Vanes are slideably disposed in the slots for maintaining contact with the cam ring during movement thereof. A servovalve has a motor and nozzles operatively connected to the pump such that increased flow through the first nozzle pivots the ring of the pump toward maximum while increased flow through the second nozzle pivots the ring toward minimum. An arm extends between the nozzles for varying fluid flow therethrough. The arm couples to the motor such that the motor moves the arm. A flow meter connects to the pump and an end of the arm for applying a force against the arm to assist in maintaining position of the arm.

Abstract: A variable displacement vane pump is disclosed which includes a pump housing having a cylindrical interior chamber, a cylindrical rotor member mounted for rotational movement within the interior chamber of the pump housing, a cam member mounted for pivotal movement within the interior chamber of the pump housing about a fulcrum aligned with the vertical centerline of the interior chamber, the cam member defining a cam body having a circular bore extending therethrough for receiving the rotor member, the cam body having lateral sealing lands formed thereon, the sealing lands having arcuate sealing surfaces defining segments of a cam arc through which the cam member pivots, and static cam seals supported within the interior chamber of the pump housing and oriented on each end of a chord of the cam arc, each cam seal biased into a continuous contact position with an adjacent sealing surface of the cam member.

Abstract: A bearing for supporting a rotating shaft receiving a transverse load, wherein the bearing supports the shaft along a load line and wherein the bearing is closest to the rotating shaft at a running line. The bearing includes a circumferential inner surface, and a lubricant bay defined in the inner surface. The lubricant bay is axially and circumferentially offset from the load line such that a resulting pressure pad of lubricant within the bay provides a hydrostatic force that forces the running line to a location substantially perpendicular to the load line. Load capabilities of a bearing according to the present disclosure, therefore, are substantially insensitive to shaft bending and do not deteriorate in response to the shaft bending.

Abstract: Variable-displacement, single-acting vane pumps in which the cylindrical cam member is adjustably supported within an outer annular cam housing to enable the cam member to be adjustably-rotated relative to the housing to adjust the geometric center of the cam chamber relative to the center of the rotor member and thereby adjust the displacement capacity of the pump between zero-flow maximum flow values. The annular housing for the cam member comprises a roller bearing assembly between its inner race surface and the cylindrical outer surface of the cam member, which minimizes the friction when the cam member is rotated during adjustment and enables the adjustment to be actuated remotely, such as by means of a small motor gear assembly.

Abstract: A variable displacement vane pump comprising a durable rotor member having journal ends at each side of a larger diameter central vane section comprising vane slots having well areas which slidably-engage a mating vane element. The present vane pump comprises an outer cylindrical cam enclosure or spacer loaded against ring seal elements to support the faces of the seal elements closely spaced from the cam faces and reduce the actuation force required for adjustment of the displacement capacity of the pump. The cam faces include a biased segment seal in the high pressure discharge arc area. The seal elements include first fuel inlet passages in the inlet arc segment thereof, and fuel discharge passages in the discharge arc segment thereof, both of said passages being open to the vane slot extensions and to the cam chamber for the continuous supply and pressure discharge of fuel.

Abstract: A variable displacement vane pump having a vaned rotor adjustably contained within a cam member for rotation between fuel inlet and fuel discharge arcs. Adjacent vanes form enclosed fuel bucket areas which are expanded and axially-supplied with fuel in the fuel inlet arc and are contracted and axially-discharge the fuel in the fuel discharge arc. Fuel circulation is improved by providing a central recess at each vane tip and/or a central groove in the cam surface to prevent trapping, stagnation and overheating of fuel at the centerpoints of the bucket areas, which overheating can result in expansion of the vane tips, scoring of the cam surface and pump failure.

Abstract: This invention relates generally to fuel control systems for combustion engines such as gas turbines used in helicopters and the like, and more specifically relates to a fuel control transfer system which permits the substitution of one fuel control device for another which is supplying fuel to an operating combustion engine, without interruption of, or adverse effect on continued operation of the engine.

Abstract: The power required for a helicopter to hover is generated (14, 82) as the ratio of current operating power in forward flight (12, 77) determined (10, 73) from data relating operating power in forward flight to power required for hover for the aircraft. The power required to hover is compared (18, 83) with the maximum power available developed (16, FIG. 2; FIG. 3) by an engine model algorithm utilizing actual engine parameters. The comparison of maximum power to power required for hover is utilized to provide an indication (22) to the pilot. The viability of the indication is indicated by a "ready" indication (26).

Abstract: Damping of a helicopter rotor drive train, the drive train including the free turbines of a gas turbine engine propulsion system, the aircraft main and tail rotors, and associated shafts and gears, is accomplished through active modulation of the fuel flow to the engine gas generator. The fuel flow is varied such that a transient torque will be developed by the free turbines which is opposite in phase to drive train resonances.

Abstract: A fuel control (23) for an aircraft engine (10) employs super contingency logic (76) in response to low rotor speed of a helicopter (130) engine failure (131) or entry into an avoid region of a flight regime following engine failure (133) to alter (161, 166-169) limits on the gas generator (30) of a free turbine gas engine (10), whereby following engine failure or in periods of extreme power need, risk of stressing an engine to its failure point is undertaken in favor of acquiring enough power to avoid a certain crash.

Abstract: The blade angle controlling pitch beam servo (26) of a helicopter tail rotor (22) is responsive to a signal manifestation (76) indicative of free turbine engine (20) gas generator speed (78) to provide torque compensation so that the helicopter airframe will not counter-rotate under the main rotor (10) of a helicopter as a consequence of the torque provided thereto by the airframe-mounted engine (20), or in the absence thereof. A trimming embodiment (FIG. 2) provides only sufficient blade angle command (82a) to compensate for that provided by fixed, collective/tail mixing (110-114). Torque compensation tail rotor blade angle commands may be applied through existing stability and autopilot actuators (30-32) or through an additional torque servo (120, FIG. 3).

Abstract: A digital fuel control (53) for a helicopter engine (20) controls fuel flow (52) to the engine in response to a turbine reference speed (62) determined in a normal mode (FIG. 5) to be a rated speed, in a fade-in mode (FIG. 6) to be incremented (117, 120) to an estimated optimum minimum speed (114, 115, 125), in an optimizer mode (FIG. 7) to be incremented (138) in a direction (137) leading to least fuel consumption (135), and in a fade-out mode (FIG. 8) to be incremented (151, 153) back to rated speed (154). The invention provides an engine reference speed which results in minimum fuel consumption during cruise flight.

Abstract: The speed (54, 56) of the free turbine (40) of a helicopter engine (20) is compared (103) with the speed (105, 106) of the helicopter rotor (10) to indicate (101, 102) autorotation, and the deceleration (108) of the rotor above a threshold magnitude (110) is utilized (81, 68, 69) to increase fuel flow (72) to the engine in anticipation of rotor speed droop which would otherwise occur during recovery from the autorotation maneuver.

Abstract: The failure of a gas turbine engine, particularly flame-out or output drive train breakage, is immediately detected and a warning signal generated. Engine flame-out is defined as an unacceptably fast gas turbine deceleration rate while output shaft failure is determined by sensing a mismatch between the engine output shaft speed and load speed.

Abstract: Damping of a helicopter rotor drive train, the drive train including the free turbines of a gas turbine engine propulsion system, the aircraft main and tail rotors, and associated shafts and gears, is accomplished through active modulation of the fuel flow to the engine gas generator. The fuel flow is varied such that a transient torque will be developed by the free turbines which is opposite in phase to drive train resonances.

Abstract: The difference in the speed (54, 56) of a helicopter gas engine (20), free turbine (40) from a reference speed (62, 64) generates (80) a desired acceleration signal (81). The difference (82) in actual turbine acceleration (84, 86) from desired acceleration is integrated (100) to provide an engine fuel command signal (67-73) whenever (88) the speed error signal exceeds (90) a predetermined threshold magnitude.

Abstract: A fuel control for a gas turbine engine has a positive displacement pump (10) which directs fuel to a constant flow regulator (14) which generates a constant or fixed rate flow of fuel. A flow diverter (16) includes a dividing device which divides the constant flow of fuel between a discharge conduit (18) connected to the burner nozzles of the engine and a bypass conduit (20) connected to the inlet side of the pump. A computer (22) which is adapted to sense various engine parameters; and calculate fuel flow controls the flow dividing device in order to apportion the flow so that the calculated fuel flow is delivered to the engine.

Abstract: A method of controlling fuel flow to a gas turbine engine includes computing the compressor discharge pressure from signals indicative of engine inlet temperature, engine speed and the computed scheduled fuel flow. The method permits accurate scheduling of fuel flow without employing a compressor discharge pressure sensor or continued engine operation in the event of sensor failure.

Abstract: A fuel control for a gas turbine engine has a fuel flow limiting valve located in series flow relationship with a main fuel metering valve, which is manually operable, to prevent engine overspeed and overtemperature conditions. A pulse-modulated solenoid valve, responsive to error signals indicative of engine overspeeds or overtemperature conditions, modulates the pressure in an actuation cylinder which positions the flow-limiting valve so that it limits flow in accordance with the magnitude of the error signals. The solenoid valve is pulsed by a redundant analog control so that, during manual operation of the main fuel metering valve, overspeed and overtemperature protection is provided to the engine. An indicator is furnished to apprise the operator of overspeed or overtemperature conditions.