US3000436A

US3000436A - Liquid fuel supply system for aerial bodies

Info

Publication number: US3000436A
Authority: US
Inventors: Lawrence Owen Napier
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1958-03-18
Filing date: 1958-03-18
Publication date: 1961-09-19
Anticipated expiration: 1978-09-19

Description

TO ATMOSPHERE O. N. LAWRENCE 2 Sheets-Sheet 1 RAM All? i 37 HERE 34 i} BURNERS 3/ e To 42 ATMOSF TO M BURNERS PILOT INLET TO ATMOSPHERE L C2 TO PILOT BURNERS To BURNERSL 21261272210 .1 K2 .Lawpczzce TO ATMOSPHERE RAM AIR L PUM P h Oh Sept. 19, 1961 LIQUID FUEL SUPPLY SYSTEM FOR AERIAL BODIES Filed March 18, 1958 WW Uvv TO ATMOSPHERE d 8 29 T0 BURNERS PUMP INLET l 362 72 8 /0 TO BURNERS TO PILOT TO PlLOT PuMP INLET BURNERS BURNERS P 1961 o. N. LAWRENCE 3,000,436

LIQUID FUEL SUPPLY SYSTEM FOR AERIAL BODIES Filed March 18, 1958 2 Sheets-Sheet 2 Fl G .3

b3 3 6 a J v FUEL FUEL INLET V INLET d i U T0 BURNERS L PILOT & BURNERS T0 PILOT BURNERS -ZI21) 6122601- vflLau/rezzce United States Patent Of ice land Filed Mar. 18, 1958, Ser. No. 722,321 4 Claims. (Cl. 158-363) This invention relates to the liquid fuel supply system of a ram jet aerial body of the type in which the fuel is supplied to burners through a pair of separate pipes each of which is provided with a fuel pump.

The object of the invention is to provide such a system in a form in which a balanced control of the fuel supply in the two pipes is obtained in a simple and reliable manner.

A system in accordance with the invention comprises the combination of a pair of centrifugal fuel pumps, an air turbine operable by ram air for actuating the pumps, a fuel supply pipe extending from each pump, a servoactuated throttle in each pipe and a servo control means in association with each of the throttles, one of the said means being responsive at least in part to ram air pressure, and the other being responsive to the fuel pressure in the duct controlled by the first mentioned means.

The invention also includes in combination with a system as defined in the preceding paragraph, pilot fuel pipes provided with fuel control means as hereinafter described.

In the accompanying drawings, FIGURES l, 2 and 3 respectively illustrate in diagrammatic form three typical embodiments of the invention.

Referring to FIGURE 1, a pair of centrifugal pumps [1, b are provided for supplying liquid fuel to separate burners (not shown) through pipes c, Both pumps are driven by a common air turbine e, the motive air for the turbine being derived from a ram air duct in the aerial body. For regulating the air supply to the turbine, there may be provided on the air supply pipe 1 an air bypass 5; leading to the atmosphere. In the by-pass is contained a throttle h which is actuated by a servo-mechanism. The latter may comprise a cylinder i containing a piston j loaded by a spring k, the piston being operatively connected to the said throttle, and both ends of the cylinder being interconnected through a restricted orifice m in the piston, or in a passage in the cylinder wall. The end of the cylinder remote from the spring is supplied with motive liquid from the fuel pipe c, through a pipe 11. The end of the cylinder containing the spring is connected by a passage 0 to a vent valve p, the closure member of which is carried by a lever q pivoted between and extending into two chambers r, s. At one end the lever 17 is loaded by a spring 2 and at the other end by an evacuated elastic capsule u, the action of the latter being opposed by the pressure of ram air which is admitted to the chamber s through a passage .9 and acts onone side of a diaphragm v which is connected to the lever by a stem s. The chamber r is connected by a passage w to the inlet side of the pump a, and the part of the chamber s containing the capsule u is open to atmosphere through a passage u Further the part of the lever q extending into the chamber r is acted on by a piston 2: contained in a cylinder y which is connected to the fuel pipe 0 by a pipe z. The arrangement is such that the ram-air pressure acting on the diaphragm v tends to hold the vent valve p closed. In this condition the spring k acting on the piston 1' moves the latter in the direction for moving the throttle h to its closed position. When the fuel pressure in the pipe c exceeds a predetermined amount this pressure by its action on the piston x and lever q opens the vent valve, and the fuel pressure then acting on the pistonj moves the latter in the direction for opening the throttle h.

Patented Sept. 19, 1961 In the fuel pipe 0 is contained a fuel-controlling throttle 4, and in the fuel pipe d is contained a similar throttle 5. The throttle 4 is operated by a servo mechanism similar to that which operates the above described air by-pass throttle h and comprises a cylinder 6, piston 7, spring 8 and restricted orifice 9. The end of the cylinder containing the spring is connected by a passage 10 to a vent valve 11 the closure member of which is carried by a lever 12 extending into two chambers 13, 14. The chamber 14 is divided into three compartments by a pair of diaphragms 15 of different diameters, these diaphragms being connected together and to the lever 12. Two of the compartments communicate with a passage 16 which at one end receives air at ram pressure and at the other end is open to atmosphere. In this passage are contained two restrictions 16 as shown one of which determines the ratio of the two air pressures acting on the diaphragms, and the other of which serves to maintain be-' tween the two restrictions a pressure higher than that of the atmosphere, the restriction adjacent to the discharge end of the passage 16 preferably being such that the air velocity therethrough is not less than sonic velocity. The other compartment is open to atmosphere through a passage 14 The chamber 13 is connected by a balancing pipe 17 with the control means of the servo mechanism which acts on the throttle 5.

In the above mentioned passage 10 is contained a transversely movable and normally open piston valve 18, the ends of which are attached to

diaphragrns

19, 20 of diiferent diameters contained in

chambers

21, 22. One end of the chamber 22 is connected by a passage 23 to the fuel pipe 0 at the outlet side of the throttle 4. The corresponding end of the chamber 21, is connected by a passage 21 to the fuel pipe 0 at the inlet side of the throttle 4. The adjacent ends of the

chambers

21, 22 are in communication with each other by way of a passage 24, and one of these ends is connected to the inlet side of the pump a by a passage 25. Further the end of the chamber 22 which is connected to the fuel pipe 0 is also connected by a passage 26 with the above mentioned chamber 13 containing the vent valve 11.

The above described control means associated with the fuel throttle 4 is such that so long as ratio of the ram air and atmospheric air pressures (as determined by the restrictions 16 in the passage 16) does not exceed a given amount, the vent valve 11 remains closed, and the fuel throttle 4 is then held in its fully open position by the spring 8 of the servo mechanism. An increase of the said air pressure ratio allows the vent valve to open. The fuel pressure acting on the piston 7 then moves the throttle 4 to a position in which it restricts the fuel flow through the throttle. In the event of an excessive restriction the dominating fuel pressure then acting on the diaphragm 19, moves the piston valve 18 to a position in which it closes the vent passage and so causes the fuel flow through the throttle to be increased.

The fuel throttle 5 is acted on by a servo mechanism which is similar to that which acts on the throttle 4, and which comprises a cylinder 6 piston 7 spring 8 restricted orifice 9 and vent valve 27. The vent valve 27 is carried by a diaphragm 28 which divides a chamber 29 into two compartments, one of which is connected to the balancing pipe 17, and the other of which is connected to the part of the fuel pipe d at the outlet side of the throttle 5 by a passage 30.

So long as the fuel pressures acting on opposite ends of the diaphragm 28 are equal the vent valve 27 is open and the fuel pressure acting on the piston of the associated servo mechanism moves the throttle 5 to a position in which the flow at the outlet side of the throttle 5 is the same as that through the throttle 4, but in the event of a diminished flow in the pipe d the pressure of the fuel in the balancing pipe 17 acting on the diaphragm 28 causes the latter to close the vent valve 27, whereupon the spring acting on the servo piston moves the throttle 5 in the direction for increasing the extent of opening of the throttle until the fuel flows in the pipes c, d are equalised.

Preferably there are also provided in parallel with the fuel pipes c, d by-

pass fuel pipes

31, 32 as shown for conveying a relatively small amount of fuel to pilot burners.

In the example shown in FIGURE 2, in which parts similar or analogous to those shown in FIGURE 1 are indicated by the same reference characters suflixed by 2, the above described action of the throttle 4 is reversed and the air operated means for controlling the piston 7 of the associated servo mechanism comprises a pair of

diaphragms

34, 35 of different diameters which divide a chamber 36 into three compartments. Two of these communicate with a passage 37 containing a pair of restrictions 37 as shown and as described with reference to the passage 16 in FIGURE 1, ram air being admitted at one end of this passage and discharged at atmosphere at the other end. The third compartment is open to atmosphere through a passage 36 One of the compartments contains one end of a vent valve lever 40 which is connected to the

diaphragms

34, 35. The other end of the lever extends into a chamber 41 and carries the vent valve 42 which controls the action of the associated servo mechanism acting on the throttle 4 The chamber 41 is also connected by a passage 43, with the part of the fuel pipe at the discharge side of the throttle. With the vent valve open the servo mechanism moves the throttle towards the fully opened position. When the ratio of the air pressures acting on the diaphragm 35 exceeds a given amount the vent valve is closed causing the servo mechanism to move the throttle to a fuel restricting position. To prevent an excessive diminution of fuel flow to the burner a by-pass 38 containing a springloaded valve 38' may be provided as shown, to ensure that at least a given minimum of fuel shall pass to the burner.

The other throttle 5 operates in a like manner to the corresponding throttle shown in FIGURE 1, in response to the control of the fuel pressure in the balancing pipe 17 Thus, the throttle '5 is operable by a servo mechanism comprising a cylinder 6 piston 7 spring 8 and restricted orifice 9 and the end of the cylinder containing the spring is connected by a passage 10 to a vent valve 27 having its closure member carried by :1 diaphragm 28 which divides a chamber 29 into two'compartments, one of these compartments being connected to the balancing pipe 17 and the other being connected bya passage 30 to the part of the fuel pipe d at the outlet side of the throttle 5 Further in each of the fuel pipes c d at positions between the throttles 4 5 and the discharge sides of the pumps a 1) are arranged

additional throttles

45, 46 operable by servo mechanisms similar to those above described. Thus, the servo mechanisms of the

throttles

45, 46 each comprise a cylinder 6a, piston 7a, spring 8a, and restricted orifice 9a, and the end of the cylinder containing the spring is connected by a passage 10a to a vent valve, the vent valve of the servo mechanism for operating the throttle 45 being indicated by 47, and the vent valve of the servo mechanism for operating the throttle 46 being indicated by 51. The vent valve 47 is responsive to the opposed actions of the fuel pressures in the pipes c d acting on opposite sides of a diaphragm 48 which carries the vent valve and is contained in a chamber 49 which is connected at its ends to the pipes 0 11?, by passages 49a and 49b. The servo mechanism for operating the throttle 46 is controlled in part by ram air pressure and inpart by fuel pressure derived from the pipe d as shown. Thus, the vent valve 51 of this servo mechanism is carried by a lever 52 the ends of which extend

intotwo chambers

53, 54. One end of the lever is-actedon by an evacuated elastic capsule 55 contained in the chamber 54 to which air at ram pressure is admitted. The other end of the lever is acted on by a spring 56 and also by an opposing piston 57 contained in a cylinder in connection with the passage 49b leading to the pipe d as shown.

The arrangement is such that in the event of inequalities occurring in the flow in the pipes 0 d the throttle control means will operate for restoring the desired equality. Thus, if the flow through the pipe 0 exceeds the flow through the pipe d the vent valve 27 will close and the throttle 5 will be actuated to increase the flow through the pipe d until the rate of this flow equalises that through the pipe 0 In addition the rate of flow through the pipe d is controlled by the rain air pressure acting on the capsule 55, and if this flow exceeds that through the pipe c the vent valve 47 will close and the throttle 45 will be actuated to increase the flow through the pipe 0 In the example shown in FIGURE 3, in which parts similar or analogous to those shown in FIGURE 1 are indicated by the same reference characters suflixed by 3, the servo mechanism which actuates the throttle 4 is under the joint control of ram air pressure, and the fuel pressure in the pipe 0 at the discharge side of the throttle. The vent valve 59 of this servo mechanism is carried by a lever 60 the arms of which extend into

chambers

61, 62. The arm in the chamber 61 is acted on by a spring 63 and a piston 64 which is subject to the fuel pressure at the end of the balancing pipe 17 connected to the discharge side of the throttle 4 The arm in the chamber 62, is acted on by an evacuated elastic capsule 65, air at ram pressure being admitted to this chamber from a passage 66 which includes a pair of restrictions 66 orifices as shown. The discharge end of this passage is controlled by a valve 68 carried by a lever 69, the arms of which extend into

chambers

70, 71. In the chamber 71 are contained a pair of

diaphragms

72, 73 of different diameters which are connected to each other and the valve lever and which divide chamber into three compartments. Two of the compartments in this chamber communicate with a passage 74 containing a pair of restrictions 74 as shown. Air at ram pressure is admitted at one end of the passage, the other end being open to atmosphere. The effect of the air pressures acting on the diaphragms is either to hold the valve 68 closed or to move it to the open position and so vary the air pressure which acts on the capsule 65 associated with the vent valve lever 60. When the air pressure in the chamber 62 predominates the vent valve 59 is held closed and the throttle 4 is moved by the associated servo mechanism to the fully open position. When the fuel pressure acting on the piston 64 predominates the vent valve is opened and the throttle then moves to its restricting position. The throttle 5 is controlled in a likemanner to that shown in FIGURE 1 so that in the event of a diminished flow in the pipe d the pressure in the balancing pipe 17 causes the throttle 5 to be moved by the corresponding servo mechanism in the direction for increasing the extent of opening of the throttle until the fuel flows in the pipes c, d are equalised.

Inladditiona control means may be provided in association with the pilot fuel pipes. In the pipe 31 is included a throttle valve 77 which is actuated by a servo mechanism 77 similar to those already described. The

vent valve 78 of this mechanism is carried by adiaphragm 79 contained in a chamber 80 the opposite ends of which are respectively connected to the pipe 31 and .arms of-which extend into chamber 85, 86. 'The arm containedinthe chamber is acted on by an evacuated elastic capsule 87 and ram air pressure is admitted to this chamber. The arm in'the chamber 86 which is connected to the balancing pipe 81 is acted on by a piston 88 which is subject to the opposed actions of the fuel pressure in the balancing pipe 81 and the ram air pressure received from the chamber 85. When the ram air pressure predominates the vent valve is held closed and the throttle 82 is held open, but when the fuel pressure predominates the vent valve is opened and the throttle is moved to its restricting position.

A similar pilot fuel control means to that shown in FIGURE 3, may be provided in either of the systems illustrated by FIGURES 1 and 2.

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

1. A liquid fuel supply system for a ram jet aerial body of the type specified, comprising in combination an air turbine operable by ram air, a pair of centrifugal pumps connected to and operable by the air turbine, a pair of fuel supply pipes connected respectively to the fuel pumps for conducting fuel therefrom, a pair of throttles mounted respectively in the fuel supply pipes, a pair of servo-mechanisms operatively connected respectively to the throttles and provided with separate control valves in response to movements of which the corresponding servo-mechanisms actuate the throttles connected thereto, a balancing pipe having one end in communication with one of the fuel supply pipes at the outlet side of the throttle therein, a first control means having a member responsive to ram air pressure and operatively connected to the control valve of the servomechanism connected to the last mentioned throttle, and

a second-control means having a member responsive to fuel pressure in the balancing pipe and operatively connected to the control valve of the other servo-mechanism.

2.- A liquid fuel supply system according to claim 1, and having a third valve situated between the control valve of the first control means and the corresponding servo-mechanism, the third valve being operable by fuel pressure for rendering the last mentioned control valve ineffective.

3. A liquid fuel supply system according to claim 1, and having in combination a pair of additional throttles mounted respectively in the fuel supply pipes, a pair of additional servo mechanisms operatively connected respectively to the additional throttles, means for controlling one of the additional servo mechanisms in response to the opposed action of fuel pressures derived from the two fuel pipes, and means for controlling the other additional servo mechanism in response to the opposed actions of ram air pressure and a pressure in the fuel pipe containing the additional throttle connected to the last additional servo mechanism.

4. A liquid fuel supply system according to claim 1, in which the said member of the first control means is responsive to both ram air pressure and fuel pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,506,611 Neal et al. May 9', 1950 2,520,967 Schmitt Sept. 5, 1950 2,851,857 Jones Sept. 16, 1958