US2872784A

US2872784A - Liquid fuel control means for jet engines

Info

Publication number: US2872784A
Application number: US345940A
Authority: US
Inventors: Lawrence Owen Napier
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1953-03-31
Filing date: 1953-03-31
Publication date: 1959-02-10
Anticipated expiration: 1976-02-10

Description

Feb. 10, 1959 o. N. LAWRENCE 2,872,784

LIQUID FUEL CONTROL MEANS FOR JET ENGINES Filed Maich 31, ,1953

FIG.

2 Sheets-Sheet 1 Zzz v ezztor O. MLaw elzce Feb. 10, 1959 o. N. LAWRENCE 2,872,784

LIQUID FUEL CONTROL MEANS FOR JET ENGINES Filed March 31, 1953 2 Sheets-Sheet 2 Event/0D jjZLa w c C? United States Patent 6 moon) FUEL corzrnor MEANS FOR JET ENGINES Application March 31, 1953, Serial No. 345,946

7 C a m (1 fil 39 8) This invention relates to liquid fuel control means for jet engines of the kind in which the air is supplied to the combustion chamber by a turbine-driven blower, the liquid fuel being supplied by a pump.

When the attendant moves the fuel control means for increasing the speed of the engine, the proper air-fuel ratio may be temporarily disturbed during the acceleration period by excess of fuel, and the object of the present invention is to enable this condition to be obviated or minimized.

The invention comprises means adapted to control a liquid-operated servo-mechanism which controls the rate of supply of fuel to the engine, and means operable by fluid pressure vdifierences associated with the air blower and turbine for actuating the said servo-mechanism control means.

In the accompanying drawings:

Figures 1, 2' and 3 respectively illustrate diagrammatically three typical embodiments of the invention.

Figure 4 is a section taken on the line 44 of Figure 3.

Referring to Figure l, a hollow body part a includes two chambers b, c. The chamber b is divided into two compartments by a diaphragm (or equivalent piston) a, and the chamber is likewise divided into two compartments bya diaphragm (or piston) e.

In the partitionwall between the two chambers is pivoted a lever j which extends into the adjacent compartments of the two chambers. The diaphragm d acts on the adjacent end ,of the lever through a stern g, alever h and a ball or roller 1', the latter being carried by an arm j pivotally attached to an adjusting screw k. :By adjustment of the position of the arm 1', the position at which the force exerted on the lever by the diaphragm can be varied to suit ditierent conditions.

i The other diaphragm e is connected by a stem m to theadjacent eud of the lever Also the lever is adapted as shown to actuate another lever 11 pivoted in a partition wall which separates ,the chamber 0 from a third chamber .9. In the latter chamber is provided a valve seating p with which cooperates a closure member q on the lever 11, the latter being lightly spring-loaded it required for normally holding the saidclosure member on the seating. The chamber 0 is provided with a drain outlet at r, and the seating p is connected by a pipe s to the liquid operated servo-mechanism.

The servo-mechanism may be .of any convenient form, and serves to control the rate of fuel supply to the combustion chamber of the turbine. In the form shown, the said mechanism comprises a piston t loaded by a spring u and slidable in a cylinder 11. The two ends of the cylinder are in communication with each other through a restricted orifice w, and oneend of the cylinder is connected by the pipe s to the valve seating p in the chamber 0 above mentioned. The other end of the cylinder is supplied with motive liquid (which may be the liquid fuel) at x. A rod 9* extending from the piston serves to actuate the out t sn msa 9 hezf e Puma a t e m ans to seasonin s-h rate o fu l u ply t t e pmf 2,872,784 Patented Feb. 10, 1959 ice bustion chamber of the turbine. When the vent valve q is closed the piston is moved by the spring u to the right for increasing the rate of fuel supply. When the valve is opened, the preponderating liquid pressure acting on the piston moves the latter to the left for reducing the rate of fuel supply.

in Figure 1, the combustion chamber of .the engine is of annular form, and is represented diagrammatically at 2. The fuel burner nozzles are indicated by 3. 'Within the space bounded by the inner wall of the combustion chamber is mounted a spindle 4 which at one end carries the turbine rotor 5, and which at the other end carries the blower impeller 6. Air is supplied to the blower from the atmosphere by a duct 7 and is discharged from the blower into the combustion chamber. After the combustion products have passed through the turbine they are discharged into the jet pipe 8 of the engine. Further, in Figure 1 liquid fuel is supplied to the burners 3 through a pipe 21 from a variable delivery pump of the swash plate type. This pump comprises a rotor 22 having bores 23 containing reciprocatory plungers 24 which cooperate with an an ularly adjustable swash plate 25 in known manner. Fuel is supplied to the pump through an inlet 26, and is delivered by the pump through an outlet 27 which communicates with the pipe 21 leading to the burners 3, and also communicates at x with the cylinder v of the servo mechanism.

In accordance with the arrangement shown in Figure 1, air is admitted at atmospheric pressure to one of the compartments of the chamber b of the apparatus above described by a pipe 9, and air at blower outlet pressure is admitted to the other compartment by a pipe 10. Gas is conducted from the combustion chamber at the inlet side of the turbine to one of the compartments of the chamber c by a pipe ll, which may include a restricted orifice l2, and gas from the exit side of the turbine is conducted to the other compartment by the pipe 13. The diaphragm d is thus subject to the difference of blower inlet and outlet pressures, and the diaphragm e is subject to the difference of gas pressure at the inlet and outlet side of the turbine, me turbine inlet gas pressure being substantially the same as that of the blower delivery pressure.

The apparatus above described is so adjusted that during normal running conditions, the pressures acting on the diaphragm d, e (or pistons) hold the vent valve q closed. But if, during acceleration of the jet engine the balance of pressures is disturbed in such a way that the pressure rise in the blower is greater than the pressure drop in the turbine, the said valve is caused to open in order to maintain as nearly as possible the desired ratio of fuel and air supplied to the combustion chamber. When the desired increased speed is attained and the balance of pressures is restored the valve is ,reclosed.

In the modification shown in Figure 2, the body parta is shaped to provide two compartments b, c which are separated from a common compartment containing one part of the valve actuating lever f by diaphragms d, e (or pistons). The diaphragm d is connected by a stem g'to the adjacent end of the lever f, and the diaphragm e is adapted to exert a force on an intermediate part of the lever by a stem m. The lever extends through a wall oi the body part (where it is pivoted) into a chamber 0 containing the servo control valve q, the latter cooperating with a seating p;

In this arrangement, air at blower in at pressure is admitted to the compartment b at 5, and air at blower delivery pressure is admitted to the compartment 0 at Ell. Gas at turbine outlet pressureis admitted to the said common compartment at 13. The servo-mechanism is connected to the chamber 0 at s. Drainage from the ham e 0 is sfi st d at .In the examp e show n fi r .2 he diaphragm id r 3 is subject to the difference of atmospheric air pressure and turbine outlet pressure, and the diaphragm e is subject to the difference of turbine outlet pressure and blower delivery pressure. The mode of action of the arrangement shown in Figure 2 is essentially similar to that of Figure 1.

In the further modification shown in Fig. 3, the body part a is divided into three compartments by two flexible diaphragms (or pistons) d, e. In the compartment be tween the diaphragms is arranged a duct 15 terminating at its inner end in an annular valve seating 16. With this seating co-operates a closure member 17 which is attached by a yoke 18 to the diaphragm d. This compartment is provided with an outlet 19 containing a restricted orifice 20. In the compartment is contained a lever f which extends into a chamber 0 and carries the closure member q which co-operates with the vent seating p, the latter being connected at s to the servo-mechanism as above described. The lever f is pivoted in the partition between the regions c, 0 and the chamber 0 is provided with a drain outlet r.

In this example gas at turbine outlet pressure is ad mitted to the compartment 0 at 13. Air at atmospheric pressure is admitted to the compartment b at 9. Air

at blower air outlet pressure is admitted to the duct at 10. Air from the duct 15 is admitted to the compartment between the diaphragms past the closure member 17, and the latter is moved by the difference of pressures acting on the diaphragm d for maintaining in the intermediate chamber a pressure which is at all times proportional to the blower outlet pressure. vThe diaphragm d is thus subjected to a pressure corresponding to the difference at atmospheric pressure and a pressure proportional to blower outlet pressure, and the diaphragm e is subject to the difference of a pressure proportional to blower outlet pressure and the pressure of the gas at the discharge side of the turbine.

From the foregoing examples it will be seen that the control of the vent valve of the servo-mechanism can be effected by a variety of pairs of pressure difierences associated with inlet and outlet sides of the blower and turbine.

By this invention temporary disturbance of the desired ratio of fuel and air supplied to the engine during acceleration of the speed of the engine can be minimized or obviated in a simple and reliable manner.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. For use with a jet engine to which air is supplied by a turbine-driven blower, and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servomechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a lever for actuating the valve, a pair of differentially movable members operable by fluid pressure differences associated with the air blower and turbine, means operable by the said members for controlling movement of the lever whilst enabling at least one of the said members to act on and impart movement to the lever, and means divided by the said members into compartments for enabling each of the said members to be subjected at opposite sides respectively to opposed fluid pressures derived from two of the fluid pressures created at the blower inlet and outlet and the turbine inlet and outlet.

2. For use with a jet engine to which air is supplied by a turbine-driven blower, and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servomechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a lever for actuating the valve, a pair'of differentially movable members operable by fluid pressure differences associated with the airblower and turbine, and arranged to co-operate with each other for controlling movement of the lever, at least one of the said members being arranged to act on and impart movement to the lever, means for subjecting one of the said members at one side to the blower inlet pressure, and .at the opposite side to the blower outlet pressure, and means for subjecting the other of the said members at one side to the turbine inlet pressure, and at the opposite side to the turbine outlet pressure.

3. For use with a jet engine to which air is supplied by a turbine-driven blower, and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servomechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a lever for actuating the valve, a pair of differentially movable members operable by fluid pressure differences associated with the air blower and turbine, and arranged to cooperate with each other for controlling movement of the lever, at least one of the said members being arranged to act on and impart movement to the lever, means for subjecting one of the said members at one side to the blower inlet pressure, means for subjecting the other of the said members at one side' to the blower outlet pressure, and means for subjecting the opposite sides of the said members to the turbine outlet pressure.

4. For use with a jet engine to which air is supplied by a turbine-driven blower, and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servo-mechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a lever for actuating the valve, a pair of differentially movable members operable by fluid pressure differences associated with the air blower and turbine, and arranged to cooperate with each other for controlling movement of the lever, at least one of the said members being arranged to act on and impart movement to the lever, means for subjecting one of the said members at one side to the blower inlet pressure, means for subjecting the other of the said members at one side to the turbine outlet pressure, and means for subjecting the opposite sides of the said members to a pressure proportional to the blower outlet pressure.

5. For use with a jet engine to which air is supplied by a turbine-driven blower and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servomechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a lever for actuating the valve, a pair of differentially movable members operable by fluid pressure differences associated with the air blower and turbine and arranged to co-operate with each other for controlling movement of the lever, a hollow body part divided by the said members into four compartments having inlets through which fluids at blower inlet and outlet pressures are admissible to the compartments at opposite sides respectively of one of the said members, and fluids at turbine inlet and outlet pressures are admissible to the compartments at opposite sides respectively of the other of. the said'members, both of the said members being arranged to act on the valve-actuating lever.

6. For use with a jet engine to which air is supplied by a turbine-driven blower, and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servomechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a

lever for actuating the valve, a pair of differentially movable members operable by fluid pressure differences associated with the air blower and turbine, and arranged to co-operate with each other for controlling movement of the lever, a hollow body part divided by the said members into three compartments having inlets through which fluids at blower inlet and outlet pressures are admissible to two of the compartments respectively, and fiuid at turbine outlet pressure is admissible to the other compartment, both of the said members being arranged to act on the valve-actuating lever.

7. For use with a jet engine to which air is supplied by a turbine-driven blower, and fuel is supplied by a pump, apparatus for preventing a temporary excess supply of fuel to the engine during acceleration thereof, comprising in combination with a liquid-operated servo mechanism for controlling the rate of fuel supply to the engine, a valve for controlling the servo-mechanism, a lever for actuating the valve, 21 pair of diiferentially movable members operable by fluid pressure differences associated with the air blower and turbine, and arranged to co-operate with each other for controlling movement of the lever, a hollow body part divided by the said members into three compartments one of which is situated between the said members, and is provided with a restricted outlet, a second valve in the last mentioned compartment, the second valve and the lever for actuating the first mentioned valve being operatively connected to the said members respectively, inlets through which fluids at blower inlet pressure and turbine outlet pressure are admissible respectively to the two compartments at the outer sides of the said members, and another inlet through which fluid at a pressure proportionately related to the blower outlet pressure by the second valve is admissible to the intermediate compartment.

References Cited in the tile of this patent UNITED STATES PATENTS 2,503,048 Ifield Apr. 4, 1950 2,570,591 Price Oct. 9, 1951 2,622,393 Edwards et a1. Dec. 23, 1952 2,638,742 Carey May 19, 1953 2,643,513 Lee June 30, 1953 2,652,813 Reuter et a1. Sept. 22, 1953 2,683,349 Lawrence July 13, 1954 2,778,191 Thompson Jan. 22. 1957