United Technologies Corporation

Other

Hamilton Sundstrand Corporation

Charles F Stearns

Robert H Perkinson

Gerald J Gorneault

Gerald P Dyer

Brian G Donnelly

Herbert W Tutherly

Kermit I Harner

Kenneth P Hansen

Lawrence S Smith

Kenneth F Vosseller

David L Chapski

Rene F Belanger

William W Hixson

Michael A Spadafora

A backup governing system for a variable pitch propeller, carried by the propeller hub which is hydraulically interposed between a main control for the propeller and a propeller blade moving, double acting piston, the backup governing system comprising a spool valve including a spool movable between a plurality of metering positions along with first and second opposing springs applying oppositely directed biasing forces to the valve member. A flyweight assembly is connected to the spool and applies a speed dependent valve positioning force to the spool in opposition to a first of the springs and in addition to the second of the springs. A piston valve is operatively associated with the second spring and operable to change the bias applied by the second spring to the spool.

Backup governing system for a variable pitch propeller

A fluid pumping system that maintains the temperature rise at a minimum value of the fluid being recirculated in the pumps during a given operating condition in the pumping system's operating envelope be disclosed. A pair of positive displacement pumps judiciously sized at different capacities are driven by a differential pumping or gearing system that is driven by a single source and cooperates with a fluid circuit delivering flow to a receiver so that the relationship of the pressure in the fluid circuit bears a given relationship to the flow capacity produced by each pump at given operating points in the operating envelope. The circuit includes a resistance in one line leading to and from one of the pumps that exhibit different resistance to the flow when flowing in one direction as opposed to the flow in the reverse direction and a valve, responding to a control for attaining the demands placed on said receiver, in another flow line in the circuit controls the capacity of each of the pumps and hence the flow being delivered to the receiver. The system is particularly efficacious for controlling fuel flow to the combustor of a gas turbine engine used in aircraft or industrial applications.

Fixed geometry variable displacement pump system

An apparatus for correcting the weight flow of fluid passing through a fuel control is shown. A bimetallic probe is placed within a metering spool to sense temperature variation of the fuel passing therethrough. A feedback mechanism senses changes in the probe and nulls the spool. The spool cooperates with specially shaped windows in a sleeve so that a percentage change in temperature allows a corresponding percentage change in fuel flow thereby offsetting changes in fuel density (and weight flow) caused by temperature changes. The probe is comprised of a rod and a perforated shell.

Metering valve temperature compensation

Fuel is directed to the stages of an afterburner by metering flow to the stages with a single metering valve and by controlling the flow to each stage by means of an integral shutoff and regulating valve. Each shutoff valve opens and closes the fuel flow to a stage as required. Each regulating valve, which is housed within a respective shutoff valve, regulates flow to each segment as a function of the pressure drop across the metering valve so that a constant weight flow to the segment is achieved.

Shutoff and pressure regulating valve

A hybrid fuel metering system has a first circuit (46, 62, 70, 76) to position a valve (18) to direct fuel to a metering valve (20), a second circuit (64, 76) to position the valve (18) to correct engine overspeed and a third circuit (78, 82, 70, 76) to position the valve (18) so that the valve (18) may be manipulated to meter fuel to the engine.

Hybrid fuel metering system

A hybrid fuel metering system incorporating a multi-function control valve (18) is shown. The valve has a sleeve (96), a piston (98) mounted for translational movement within the sleeve and a spool (100) mounted for translational movement in the piston. The piston has three positions for cooperating with the sleeve; a variable first position for metering fuel to an engine (12), a second position for directing fuel to a metering valve (20) and a third position for shutting off flow to the metering valve and to the engine to correct engine overspeed. The spool has two positions a first position to shut off flow to the engine and to the metering valve to shut off the engine and a variable second position to position the piston to meter flow to the engine.

Multi-function fuel metering valve

A pressure regulator (75) of a flow control system includes a pair of orifices (140 and 145), the effective areas of which are controlled by a pair of flexible closures (150 and 155) unidirectionally stiffened against fluid flow thereagainst. The closures remain flexible in an opposite direction so that when one of the closures is fouled with contaminants, it does not impede the operation of the remaining closure.

Pressure regulator

Sensed pressures are applied to a differential pressure sensor such that one-half the sensed pressure drop is applied to each of a pair of redundant pistons. Failure of one of a pair of bellows which seal opposite faces of the pistons from one another effects application of the entire pressure drop across the piston associated with the remaining, operable bellows for fail-safe operation of the sensor.

Differential pressure sensor

Variations in pressure drop set by an inline pressure regulating valve (70) are minimized by a spring (97) having a rate which is a select function of certain characteristics of the geometry of the flow controller and the fluid flows required to be handled thereby.

Minimization of pressure drop variation in flow controllers

The basic gas turbine engine hydromechanical fuel control is adaptable to different engine configurations such as turbofan, turboprop and turboshaft engines by incorporating in the main housing those elements having a commonality to all engine configurations and providing a removable block for each configuration having the necessary control elements and flow passages required for that particular configuration. That is to say, a block with the elements peculiar to a turbofan engine could be replaced by a mating block that includes those elements peculiar to a turboshaft engine in adapting the control for a turboshaft configuration. Similarly another block with those elements peculiar to a turboprop engine could replace any of the other blocks in adapting the control to a turboprop configuration. Obviously the basic control has the necessary flow passages terminating at the interface with the block and these flow passages mate with corresponding passages in the block.

Fuel control for gas turbine engines

The fuel flow for a turboprop or turboshaft engine is provided by a plurality of parallel circuits each of which supplies a portion of the fuel to the engine with different valves controlling the flow through each of the separate circuits. In the turboprop engine there is imposed on the parallel flow circuits a sensing device that determines the pressures in certain of the circuits and selects the appropriate pressure for signalling a pressure regulating valve whereby to vary the pressure drop through the fuel control.

Fuel circuits for fuel controls

A flapper valve having a negative rate characteristic is variably opened by an external force and controls fluid pressure to a piston which moves, in response to this pressure, in order to return the valve to a null position. A positive rate flapper valve applies force to the negative rate flapper valve and balances the fluid pressure in the negative rate flapper valve, thus providing high sensitivity negative flapper valve operation in the null position region and a negative rate in the region to overcome piston friction, without instability.

Negative rate compensated hydraulic servo system

Fuel flow to a gas turbine engine is controlled in response to power lever position and CDP. Fuel is supplied to the engine through three fuel flow regulating circuits which are in parallel. In one of these circuits there is a valve which establishes a minimum fuel flow which decreases with increasing power lever advance. In a second circuit there is a valve which modifies fuel flow in response to CDP. In a third circuit there is a valve which modifies fuel flow in response to CDP and receives fuel from a valve which opens with increasing power lever advance. The fuel control system includes a low power sensitive torque motor which may be activated to increase the pressure drop across the three circuits whose flow thus increases proportionally. Normal engine operation is obtainable without the use of the torque motor which provides an interface to an electronic control unit which senses various engine and ambient parameters and activates the torque motor in order to modify fuel flow accordingly.

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East Longmeadow, MA, United States of America

Charles F Stearns