US2938341A - Valves for controlling re-heat fuel on air-craft - Google Patents

Description

May 31, 1950 D, T. A. MILLER 2,938,341

HEAT FUEL oN AIR-CRAFT VALVES FOR CONTROLLING RE Filed Jan. 18, 1957 Etam,

enf-Cof .D TJMzLZ/Lef *UNI ILl VALVES FOR CONTROLLING RE-I-IEAT FUEL N AIR-CRAFT David Thomas Anthony Miller, Don Mills, Ontario, Canada, assignor to `loseph Lucas (Industries) Limited,

Birmingham, England Filed nm. 1s, 1957, ser. No. 634,981

s claims. (ci. `sti- 119.223)

This invention relates to means for controlling the supply of liquid fuel to an aircraft re-heat system which comprises a plurality of individually operable burners.

The object of the-invention is to provide a convenient and reliable arrangement of valves adapted so to operate that when an additional burner is bronghtinto action, temporary impoverishment of the supply to a burner or burners already in action is obviated.

`A valve arrangement in accordance with the invention comprises the combination of a plurality of main fuel control valves corresponding in number to the' number of burners, each such valve being movable to its open position by fuel or other iiuid pressure in a common supply pipe, an additional valve movable to its'open position by fuel or other uid pressure'in association with each of the first mentioned valves excepting one, the additional valve serving to control the flow of liquid fuel from a branch supply pipe and being operable prior to its associated main Valve for effecting preliminary iilling of -the associated burner supply pipe, and a plurality of independently operable control valves under the'y control of the pilot for controlling the lfuel operable valves.

The accompanying drawing illustrates diagrammatically a typical embodiment of the invention.

f Referring to the drawing, the re-heat fuel is supplied by a pump to a common feed pipe a through automatic control means which are shown in the left hand portion of the drawing and will be described later. rPhe pipe a isy connected by a series of branches as a1, 12, va3 and a4 to the valves forming the principal subject of the invention, and from these valves the fuel can iiow'through other branchesas b1, b2, b3 and b4 to the re-heat burners. The branch pipe a1 leads to a valve box c1. In this is contained a closure member d1 which cooperates with a seating e1 in communication with the outlet branch b1. The closure member is secured to one end of a bellows f1 and is loaded by a spring g1 which (when the system is inactive) serevs to Ahold the closure member in contact with its seating. In the closure member are formed passages as shown which include a restricted orifice 'h1 through which fuel can flow through the bellows and a pipe il to a control valve box jl. The latter contains a closure member k1 which is normally held on a seating m1 by a spring n1 and is retractable lfrom its seating by an electromagnet o1 under the control of the pilot. When the closure member is moved off itsv seat-ing, fuel can flow from the valve box to a pipe p1 leading to a sump.

The arrangement is such that when the pilot desires to bring the first re-heat fuel burner into action he actuates a switch (as described later) for bringing the solenoid ol into action. The associated `closure member k1 is thereby moved away from its seating, and fuel can then flow from the interior of the bellows jl and through the pipes i1 land p1 to the sump. The resulting drop of pressure within the bellows enables the pressure of the fuel in the branch al to move the closure member d1 away from its seating and so allow fuel to iiow through the branch b1 to the burner.

2,938,341 Patented May 31, 1960 Vi ce A similar valve to that above described serves to oontrol the supply of fuel to the second re-heat burner. It comprises a valve box c2, a closure member d2, for controlling the flow to the branch b2, a bellows f2 and spring g2. But before this valve is opened it is necessary to ensure that the pipe b2 leading to the associated burner shall be tilled with fuel. To satisfy this requirement a second valve is provided in the valve box c2. The second valve comprises a closure member dx controlling a seating at the entrance to a passage bX leading to b2 and a bellows fx loaded by a spring gx. Fuel can enter the bellows through a restricted oriice hX and can. pass from the bellows through an orifice g3 to a pipe iz leading to the valve box j2. This latter contains a similarpilot-controlled valve to that contained in the valve boxjl. Fuel is supplied to the bellows jX by `a bypass pipe. ax connected to main passage a, and can iiow from the` valve box i2 to a sump through the above mentioned pipe` p1 which is common to all the valve boxes jl, jg, j3 and j4,

Fuel can also flow from the bellows f2 through an ori-- tice q2 situated adjacent to the orifice qa, and the flowv through these orifices is controlled by a lever r carryingn a pair of closure members s which can close either of the said orifices. Thelever extends through a seal to a compartment which is connected at t to the part of t-hev aircraft containing the re-heat burner, for example, the propulsion duct or jet pipe of the engine. rThe said cham-1 ber also contains a bellows u which is loaded by an adjustable spring v, the lever r being connected to a. stem yl interconnecting the spring and bellows. The interiorof the bellows' is open to one end of a passage z which at its other end is connected to the end of the fuel pipe b2 at a position adjacent to the burner supplied by this pipe.

The arrangement is such that when the valve in the valve box jl is closed, both of the closure members dZ and dX are in their closed positions. When the pilot opens the valve in j2, fuel can flow from the pipe ax, through the bellows fx, oriiice g3, and passage i2 to the lvalve box, and thence along p1 to the sump. The elfect of this is to cause the closure member oX to be moved off its seating, so allowing fuel to iiow along bX to the branch b2, and so cause the pipe leading to the associated burner to be filled. When lled, the fuel pressure in the pipe is transmitted along the passage z to the interior of the bellows u. The effect of this is to move the lever r in the direction for closing the orifice g3 and opening the oriiice q2. Fuel can now liow from 4the bellows f2, through q2 to the valve box i2, and thence to the sump, so causing the closure member d2 to be" moved oi its seating, and allowing fuel to flow to the second re-heat burner from a2 to b2. Y

For controlling the supply of fuel successively tol the other burner supply pipes b3 and b4, there is provided for each a control means similar to that associated with the burner b2, the said means being contained in valve boxes c3 and c4 and controlled by electromagnetically operable Valves i3 and i4.

It will be evidentthat itis also desirable to be able to control the rate of supply of fuel to the valves above described from the supply pump, so that the fuel vshall be supplied at an equal rate to all the reheat burners when two or more are in action, and so that the rate shall alsobe Variable with the speed of the blower which supplies the air for combustion of the fuel. For this purpose control means as shown in the left hand side l of the drawing may be employed.

assenti end 'is connected nto a lever'7 through a tension spring 8. Also the lever is loaded by an additional and adjustl' able tension spring 9. The end of the cylinder remote from thethrottle is open to the fuel.A pipe a. by. wayof a litteredV orie 10.' Also it bohrnmnicatest'witn a vent .Sage lil which is controlled bya closure mei-ober 112 on oneend of thelever 7. When the vent "passage is closed, both V sides rof Athe piston are subject to the fuel pressure. But when the said passage yis open, a lpre'ponderating fuel pressure acts on theunder side of 'the' 'piston causing the latter to move upwardly forincreasing the passage between the throttle and throat. Control of the lever 7 is effected by 'the action of blower 'air pressure on an elastic evacuated bellows 13 contained in a chamber 14, one end of the bellows being connected to theend of the lever remote from the vent passage by arod which passes through a seal, 16. The arrangement is such that with increase of blower speed, and consequent increase of blower air pressure, the lever 7V is moved in theA direction for openingthe 'vent passa-ge 411k, so causing the throttle 4to be moved in the direction foi-.increasing the rate of flow of fuel past the throttle. In the example illustrated the action of theblower is also controllable by the pilot through a valve 17. valve includes a closure member 18 which is loaded by a `spring 19. Blower air is admitted at 20 through a restricted orifice 21 and can flow to atmosphere through a vent 22, at a rate determined by the position of the closure member. The said member is operable by a cam 2,3k on a spindle 24 which can be actuated by the 'pilot throughga handle 25'.V Also there are mounted on the spindle 24a series of earns 26, for actuating -`swtitcll1es-27 arranged to control 'the circuits containing the solenoids the 'valve boxes jl, i2, i? and i4. When all thevalve's inthesaid boxes are closed the closure member 18 occupiesi'ts vfully open position. vOn bringing the rstreheat burner into action by 4actuation of the handle 2 5, the camr23r, will impart a smallv movement to'the closure rneinbier 18 for diminishing the air ow to the ventf22 and, so increasing the air pressure acting on the bellows 13, thereby causing the throttle 3 to be moved to a position in which adequate fuel caln'passjto the first reheat burner. To bring the second burner'into action a fuither movement is given to the handle 2S, causing the second switch to close the 'circ'uitof thev second solenoid,

the burner being maintained in action. The veEectof movement is tocause the closure member 18 to electl a further restriction of air ow to the vent and donsequently cause, a further. increas'eofair pressure on the bellowsv 13, so causing a further 'inceaseof the throttle opening. A like action occurs when each of other refheat burners is brought into action, so las to. ensure an adequate flow of fuel past the throttle 3 to supply fuel to all 'the burners equally. l l

Passing now to the other additionz'il controlv means shown in the drawing, this servesto regulate the rate of fuel ow to the burners in response tothe fuel pressure difference at the 'entrance and exit sides Vof 4the throttle 3 above described. t Thiscontrolfineans comprises a valve box 28 whichisconnected to the fuel pipe a as shown, and in which is contained a throttle 2`9-coop erating with a throat 30. The throttle isconnected 'to a piston 31 contained in a cylinder 32, the piston being loaded at one side by a compression spring 33.r lower part of. the cylinder containing the said spring lis connected to the `exit side of the throttle through a passage 34 containing a restricted orifice 3S.y 'Ihe upper part of the cylinder communicates with the feed pipe a at the entranceside ofl the throttle 29. Alsofthfe're 'is provided a vent 36 which is controlled by `a closurenjlembed 37,

the latter being carried by fa exiblediaphagm 38 which',

separates twocompartments 39, 40 is loaded byacompression spring-41 arranged 'to' movethe closure member to the position in whichY it closes. the. ventf`36.

cmparmient 40 Cmmusstes with. the entrante side of the throttle Z9 by way of a passage 43; .'lhne ooinpr'nt 39 communicates with the inlet side of the previously mentioned throttle '3 through a pipe 44. The diaphragm 38 is subject to the pressure difference between the inlet and outlet sides of the throttle 3. When this exceeds a given amount, the closure member 37 opens thetventldcausing thepiston 31 to move the throttle -29 in the direction for restricting theY fuel flow pastthis throttle.

The joint action of the two control means above described isfsuch that when only the lrst re-heat burner is in action the throttles 3 and 2.9 will takeup positions such as w-ill allow only the Vllow of the fuel required by this burner. When the second burner is brought into action both throttles will move in theA direction for permitting an increased fuel flow. A similar action occurs when each of the other burners is brought into action. The invention is not, however, restricted tothe particular construbctional; detailsY ofthe valves above described minor details may be varied4 Without departing from the essentialv features of the invention. Thus, forY example, instead of electromagnets for controlling the valves in theparts jl, 1217" and i4, any equivalent mechanical means may; be employed, the cams 26A being then arranged to act directly on the stems (as k) in the valve boxes jl, 1?, jiand i4; Also whilst it is convenient to employ the pressure of the fuel for actuating the various fuel control valves, thisl is not essential, as any other pressure iiuid may beg-usedfor this purpose, in which case the valves as d1, d 2, would beconnected to the corresponding fuel valveslocated in thefuel pipes.

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

't l: Means for controlling the supply of fuel to re-het burners onl an aircraft, comprising in combination a plurality of burner supply pipes, main control valves respectively connected to the burner supply pipes for controlling the admission of fuel thereto, actuating devices responsive Lto Vfluid pressure for opening the main control valves, additional control valves respectively connected to all except oneofthe burner supply pipes for controlling theadmissionof fuel to the corresponding burner supply pipesindependently of the main control valves, actuating devices responsive to huid pressure for opening the addi.- tional valves, a pressure-huid supply conduit from which duid under pressure has access to the actuating devices ofthe main and additional control valves, control devices responsive to fuel pressures in the burner supply pipes to which fuelisj admissible under the control of the addi# tional control valves, members movable by the control devices into and out of positions in which they serve toprevQIlt opening movement of either the correspondingmaincontrol valves or the additional control valves, said movable members permitting said main control valves to open when the pressures in the burner supply pipes connected thereto attain a predetermined value, and said movable members permitting said additional control valves to open when the pressure in the burner Y supply pipes connected thereto is below said predetervalue and thereby enable the additional control valvesj to be opened before the corresponding v'riia'in control valves ,as the pressure builds up in said supply pipes` from` below said predetermined value to above said predetermined value, and a plurality of manually controllable and relatively movable valves arranged l`to serve, when closed, for preventing opening movements of the main and additional control valves bythe correspending actuaing devices.

2f. Means for controlling the supply of fuel to resheat burners on anV aircraft, comprising in combination 'a plurality of burner supplyl pipes, main control valves respectively. connected to the burner. supply pipes for` controlling theadmission of fuel thereto, actuating devices responsive. to Huid pressure for opening the main conti-011 valves, additional control valves respectively connected to all except one of the burner supply pipes for controlling the admission of fuel thereto independently of the main control valves, actuating devices responsive to uid pressure for opening the additional valves, a main fuel supply conduit from which fuel under pressure has access to the actuating devices of the main and additional control valves, control devices responsive to fuel pressures in the burner supply pipes to which fuel is admissible under the control of the additional control valves, members movable by the control devices into and out of positions in which they serve to prevent opening movement of either the corresponding main control valves or the additional control valves, said movable members permitting said main control valves to open when the pressures in the burner supply pipes connected thereto attain a predetermined value, and said movable members permitting said additional control valves to open when the pressure in the burner supply pipes connected thereto is below said predetermined value and thereby enable the additional control valves to be opened before the corresponding main control valves as the pressure builds up in said supply pipes from below said predetermined value to above said predetermined value, and a plurality of manually controllable and relatively movable valves arranged to serve, when closed, for preventing opening movements of the main and additional control valves by the corresponding actuating devices, each main control valve comprising a closure member for controlling the ow of fuel to the corresponding burner supply pipe, a spring acting on the closure member in the direction of closing it, a bellows carrying the closure member and contained in a chamber communicating with the main fuel supply conduit, and means for permitting a restricted fuel ow through the bellows under the control of one of the manually controllable valves.

3. Means according to claim 2, and having in combination with the main fuel supply conduit a rst throttle located in said main fuel supply conduit responsive to air pressure, a second throttle located in said main fuel supply conduit which is responsive to a fuel pressure difference created by the throttling of the fuel through the first throttle, and is arranged in series with the first throttle to serve in conjunction therewith for controlling the rate of fuel supply to the main control valves, and manually operable means for varying the air pressure to which the rst throttle is responsive.

References Cited in the file of this patent UNITED STATES PATENTS 2,127,172 Hermitte Aug. 16, 1938

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