US2586224A - Fuel burner system - Google Patents

Description

Feb. 19, 1952 HARRls ETAL 2,586,224

FUEL BURNER SYSTEM Filed May 17, 1948 2 SHEETSSHEET l 54 FIE E 6\ INVENTOR5 U K) fier/A flaw/15 Marcus [0/6790 1952 R. L. HARRIS ET AL 2,586,224

FUEL BURNER SYSTEM Filed May 17, 1948 2 SHEETS-SHEET 2 Patented Feb. 19, 1952 Robert. L. Harr s Calif assignors to;

and. Marcus. Lo hitonal i erk leyt Yuba. Manufacturing. Com.-

pany. San Francisco, Calif-31a corporation of California 1s Claim 1 Qur invention relates to: means especially use:

fut-in. hand-lingliquid fuel atomizedhin an air stream.

O r inv io p rt ins o hurnersi-n which the amount. of fuel burned varies from; time. to. time over a, relatively wide range and particularly. to burners utilizing pressure atomization, tobreak p liquid fuel into readily combustible droplets. As: an example, it. an be. a sumed .that.a m nium; atom zation pressu e i one. hundred. p unds.

per qu rein h and thatfithe. amount of; fuel rangesfrorn a gredetermined minimum amount.

to. a maximum eight times that. amount. The prop rtion l increa in fu l discharged iroin a. nozzle is equal. to theseuare root: of the pro.-

portional increase in pressure. So, fora. quantity.

range of eight the pressure must be increased sixtyfour fold. The hundred-pound. per, square inch minimum pressure necessary for atomiza= tion must be raisedto 64400 pounds. pen square inch. In. any ordinary,v commercial sense. the pressure required" proliiloitive.

As an alternative. to. building the; system to. stand. this pressure,v the. maximum amount. of. oil or fuel can be pumpedand allbutthe amount in: stantly utilized-tan be. bypassed. Eiehtetimes the amount of fuelcburnedf must. necessarily be pumped even it onlya minimumfire isrequiredt.

Another alternativeisto provide-a n zzle. operat-. ing at. substantially a uniform. pressure, but nary? m automaticallyin area. Such. nozzles aretheoe retioally possible. butialte Practically either. 12 10.9, hibitively expensive or arev not name-11y work-J able. under th usual. r ugh. conditions of op:- eration.

It is therefore, an object of our'inventionto, provide. a fuel burning, system in.whioh...the. neoessary atomizationv pressure. is sustained; the, range in amount of fuel dischargedlisreletivflly Wide and in which a relatively simple nozzleand' moderate pressures, are. utilized.

Another object of the invention is. tn provide. a. means for metering. fuel over. a relatively wide.

quantity range.

An additional obj ect. of the invention isto. provide a fuel burning system .quicklyresponsilve to. variations in demand.

Another object of the invention is. o ptovidea fuel burning system which meters theiuelaw curately yet requires only a. simple regulatingmechanism.

A further object of the inventioni t0 DIQY a fuel burning. system capable ofsusfiained consistent operation. I

An additional objeot of the invention is to. pro.-

adcl tional oln'eot of t e. invention. isto pro-H vide: a. fuel. burning-system readily adjustable when installed on when in. use, to. vary thechar eteristiosoi-the.sysiie nascdesired.-

A till. furthenobgectoil the invention to pigouide: a fuel burning; syst m .oapahle. oil meet ns. closely the requirements. for comb stion. of wi y vary quantities of iiel Other .Qbifiolfls together. with th ioregoing. ar attained inthe. embodimentofi theinvention (le cribed:- in the aooompanyina description andiilflustratedl in the accompanying drawin s in. which Figure. 1. is an isometric .tiew in .diaerainm t o form. or a fuellhurning. system construoted, aoordence without invention... porti ns liningbro-v n waytodisclose interior:oonstruotion.

Ei'gurez a cross:se tionthtoush a .fuel' m t.- ering valve utilized in our system. the planeof ection generally being a median, vertioalplane.

Y Eie re 3 a cross-section similar to'Figure 2 ut. taken. on the. planes indication. he lines. 3-301 E 'gurez;

Figure. 4' a. oross=section generally on. a me iam longitudinalplane. through. a iuel nozzle utilized in connection with ourfuel burning sys-- mm.

In. itspref rred; form our; iueljhuming. system comprises a clifterential' pressure, no zl connect.- e iibu. a conduit. to a iiuel. puma driven at a speed variableg ubstantialiy. inaecprtlancewith. the olemend upon .theifuelburning, systems The con.-

duit is provided" withia m ans. for releasing $1.1 1".

plus fu lactuated;automaticallyto vary the presu e upon the nozzle til-provide the req uisiteoutput; Jitter a predetermined rate 01? dischar e as the. amou tof. discharge ncr ases with; the

pressure on. a ll' f. the nozzlesbeine oon urn ntiyregulated;

Whileiour fuel burning; systemis. susc ptible to f rmu ation. in. many diiferent la ely. see p ndentupon the particular insta lation. it .h s

beensuec ssfully embodied-as. shown. herein. It." isil ustratedl by an. xample utilizing, a m nimum atom ine pr ssure of ne hundred; pounds per square inch. on fuel; oil of approximately new two .degreesigravity' and? with a. i i. mtiti''' 28386 f om a. min mum ftour gallons perhoui: to a;

maximum of thirty-two gallons per hour. This mechanism is utilized in connection with the steam power plant disclosed more completely in our co-pendingapplication entitled Steam Power Plant, filed May 1, 1948, Serial No. 24,656. In that power plant, an internal combustion engine drives not only an air blower but also a fuel pump for expelling the fuel through a nozzl to mix with the air.

In the present illustration, the speed of the driving mechanism 6 is regulated by a mannually controlled handle I so that the speed of the driven blower (not shown) is correspondingly controlled. The engine 6 also is effective through a drive shaft 8 to impel a positive displacement fuel pump 9, the speed of which corresponds to that of the engine. The inlet ofthe pump is joined by a conduit H to an atmosphericpressure tank |2 containing a body l3 of fuel such as oil. The pump discharges the fuel through a conduit l4 at any pressure within the capacity of the pump, a range of several hundred pounds. The discharged fuel flows into a valve l6 effective in one position to divert the fuel through a return conduit H to the tank l2. In this valve position, the pump 9 merely recirculates the fuel oil. The valve l6, in another position, directs the pumped fuel into a conducting line l9 leading to a fuel oil valve generally designated 2|. Within the valve 2| the fuel is regulated and distributed, any excess being returned to the tank |2.

The valve 2| is comprised ofa casing 22 in cluding a block 23 secured by fastenings 24 to a base 26. The block 23 is provided with a transverse bore 21 into which the line |9 extends. The bore 21 is therefore supplied with fuel under pressure from the pump 9 whenever the valve a is so directed. Oil supplied to the bore 21 is free to enter a vertical passage 28 and from it to enter a cross bore 29 from which a conduit 3| extends to a first nozzle 32.

The nozzle 32 includes a body 33 having a bore 34 communicating with the conduit 3|. The bore also merges with a passage 36 terminating in an annular groove 31 concentric with the axis 38 of the nozzle. In an enlarged bore 39 is disposed a plug 4| firmly clamping a flexible diaphragm 42 in position overlying the groove 31. The diaphragm also overlies an axial bore 43 extending to a, receptacle 44 in which a standard nozzle tip 46 is screwed. The nozzle tip is of the sort usually available for oil burners and in'- cludes not only a filterscreen but also passageways for tangentially directing the fuel into an internal chamber from which'the fuelspins out through a central discharge orifice 41 in a fine spray. The nozzle tip 46 is rated to discharge a set amount of fuel, say four gallons per hour, at astandard atomizing pressure of one hundred pounds per square inch.

"When pressure is exerted by fuelin the annulus .31 upon the diaphragm 42,, the diaphragm is'fdisplacedtoward the left in Fgure 4, andthe fuel fiows from the annulus into the central'passage 43. When the diaphragm is "displaced it is unseated from an annular seat 48 and its effective area is suddenly increased. The pressure, effective upon a suddenly augmented area,

abruptly lifts the diaphragm fromits sealing po sition and opens the passage 43. Thus, while an increase in pressure against the diaphragm 42 may be relatively gradual, as soon as it barely unseats the diaphragm, it quickly accomplishes the remaining diaphragm movement so that the fiow of fuel to the'nozzle tip under full pressure is initiated abruptly. correspondingly, even though the pressure of the supplied fuel in the passageway 36 decreases gradually, as soon as the diaphragm 42 begins to seat, the area available to the pressure is abruptly reduced so that the diaphragm then quickly blocks the passageway 43. The fuel still under a moderately high pressure a little below the opening pressure is'retained within the conduit 3| while the fuel remaining within the passage 43 and the chamber of the nozzle tip 46 falls to atmospheric pressure.

Since such fuel is usually gassy, it foams and expands and continues to discharge from the orifice 41 while its pressure is reducing. The abrupt seating of the diaphragm traps all of the oil in the line I9 under a moderately high pressure, no matter how long the line nor the amount of oil, and leaves so little expanding fuel within theremaining passageways that little if any fuel dribbles from the nozzle tip 46. Thus the nozzle both at starting and at stopping so quickly discharges either not at all or at substantially one hundred pounds per square inch pressure that all of the ejected fuel is appropriately atomized and there is little or no intermediate pressure operation with resulting poor atomization and dribbling of the fuel.

To assist the diaphragm 42 in its operations and to provide an appropriate setting or adjustment for the pressure response of the diaphragm, the plug 4| carries a piston 5| abutting and pressed by a spring 52 against the diaphragm. A cap 53 open to the atmosphere by means of a hole 54 engages the plug 4| and is screwed to a position so that the spring provides an appropriate opening pressure and a corresponding closing pressure. Since the opening and closing pressures are different because of the different areas of the diaphragm available at the opening and closing events, the nozzle 32 as a whole is characterized as a differential pressure nozzle.

As the fuel from the engine driven pump fiows in through the bore 21 and the connecting passageways 28 and 29 to the nozzle 32, the nozzle opens at, say, one hundred pounds per square inch pressure and supplies fuel to the air stream from the engine driven blower. Though the oil pump and the air pump are simultaneously driven, the amount of fuel which issues from the nozzle is correctly proportioned to the air only at one particular condition or speed of operation. To avoid pumping many times the required amount but to makev sure that there is no deficiency of fuel, we drive the pump 9 to provide a small excess capacity, and then by-pass the small amount of excess fuel. This affords compensation for any possible long term drop in efficiency of the fuel pump 9 or in other leakages or discrepancies v in the system.

As part of the by-pass mechanism, there is screwed into the block 23 to form a continuation shunt path from the nozzle 32, but when the valve 58 is unseated, fuel can escape through it from the passageway 29 and so by-pass the nozzle 32 By-passed fuel fiows through apertures 62 in the shield into a central chamber 63 of the housing base 26 from which itpasses through a chan- 7 d'nel' 64 into a cam chamber 66 and from that chamber through a drain pipe 81 at substantially atmospheric pressure back to the tank l 2;. By regulatingthe; pressure exerted by the spring. 6!, the valve 5;" is correspondingly pressed tightly or loosely against-its seat 59 and: either precludes the by-pass flow of fuel from the nozzle passage 29' or regulates the amount of fuel by passed and correspondingly the remaining amount of fuel ex polled from the nozzle.

To operate the" by-pass spring 6 I, there is pro: vided an adjusting screw-68 engaging the lower end of the spring and held by a lock nut69 in ad, justed positiondn a cam follower H operable in a. cylinder lz in the base 26 between the chamber '63 and the. chamber 66. The follower H. is pres vented from-rotating by a set screw l3fihut is freely reciprocable in accordance with the con tour of a first cam 14 disposedwithin the camchamber. 86 and held on an operating shaft why a set screw IT. The shaft 16- is mounted in: bear, lugs 18 and 19*in'the base 26 and is rotatableby an external lever 80. Oil leakage from the housing chamberfifi ispreclud'ed by a shaft seal 81' and by av cap- 82'. A rod 83 pivotally joins. the. lever 80 and the operating lever i. I

The operating lever, being effective to. control the general operation of the driving motor 6 and correspondingly the speed-of the air blower and of the pump 9, is-likewiseeffective almost simul.-. taneouslyto rotate the shaft 76 and to-revolve the first cam 14. The cam is provided with an actu. ating surface 84,-the portion having anangu-lar extent between a center line 85'and a center line 86- constituting what is termed a first range. When the cam follower is-in the position shown in Figure 3, the screw 68 isadjustedandlocked in a positiorr'such that the pressure of the. spring Bl permits suflicient'fuel to by-passthe valve 58 so that the remaining amount of fuel discharges from the first nozzle-32 at one hundred pounds per square inch. This afiords the minimum quantity of four gallons per hour. As the lever I is operated to increase the speed of the engine 6 and of the pump 9 and of the air blower, the output of the pump 9 is not necessarily increased in proportion tothe output of the air blower. Normally, the relationship is not-a simple pro portion. To obtain the proper fuel-air propore tions at different speeds, difierent amounts of fuel must be bypassed by the valve 58 atdifferent speeds.

Accordinglyf'the contour of the firstrangeof the cam surface 84 is made such that in eachposition of rotation of the cam in response to opera-. tion of the lever l, the pressure of the spring 6! is correspondingly varied to govern the amount.

of fuel by-passed. There is thus left-for dischargev through the first nozzle- 32 an amount of fuel exactly proportional to the amount of air avails. able for combustion. The proportionate amount. of fuel is readily changed, if desired, to. meet-vary ing conditions either loy changing the adjustment of the screw 68', by substituting a spring 6| of diilerent characteristics, by replacing the first cam 14 as a whole,- or by varying the shape of the surface 84 exactly to produce the desired re sults. Since the first nozzle 32 is usually utilized in starting combustion, a somewhat rich mixture, that is, one having a high proportion of fuel. to air,; is initially provided by slightly increasing the radius-of the initial part. of the surface 84.

Asthe spring 6t compressed as the cam'rqtates; the pressure of the fuel suppliedto the. firstv nozzle 321s continually increased until it. reaches a. predetermined. value, say, four hundred pounds fromthenozzle when. supplied at four hundredpounds per square; -inch. pressuresis approximately twice thev amount of .fuel discharged when the supply is..only. at. one. hundred poundsper square inch pressure. .flThat: is rora typical nozzleythe discharge. at .fourhundred pOLlndS per square inch. supply pressure. is approximately: eightgal- Ions-pen hour if the dischargeeatthe standard: onehundredpoundsper square inch supply. press surc'is the rated. four gallons per hour... As four hundred. pounds. per square inch pressure is about as higlraszit. is desired to operatethe system, we provide means-for continuing the increasein' one. put without: exceeding this pressure For: thatreason'a second introduced into the syste The nozzle: 9k is identical with the nozzle '32- .and1is. of a similar rating-.that isv to say, charge at one hundred pounds per square. inch supply pressure. It. is ioined-by a. conduit. 92130- the block 23 of the through an opening 93: This passageway lain-i tersected by a bore. 94

coilspring allure: screweldinto. the.

block 23. Communication between-the. bore-21 and the passage 93 is normally prevented. as the ball 91 is held on the seat partly by the. spring, 98- but largely by the unbalanced fuel pressure exerted thereon, since. the. chamber .63; is: about at atmospheric pressure. To dislodge the ball: and permit communication, the. bore 94 is nar-. rowed and threaded to receive a. sleeve ing' packing H12 andv a packing, mitt-G3 at; its lower .end and providing a very close sliding fit fora rod [04. and extends from therpacking nut; H13 ta-contact an adjusting screw [06 locked-by a. nut. ill-l in position in the cam follower H.

During the fore part of themotion of. the cam, 14 in its first range, there is sufllcient clearance between the upper end of the rod Hi4; ands the ball 91 so that the ball remains seated-and. pres vents fuelfiow into: the passage 93.. However; just before the cam surfacetl: compresses the spring 6!- to produce a discharge pressure ofiapproximately four hundred pounds per: square inch.

for the first nozzle 32, thesame cam surface orsubstantially-the same-contour of the'cam having gradually lifted the rod IM against the. ball-Aft,

i tlnally effective to dislodge. the ballahruptlyr from its seat-member 96'. The. linear. motion. re:

the spring 6 i, there is only a small: change. in the spring controlled pressure as the ball 91: is: dislodged.

The adjustments are made. in such a fashion (preferably by pressure gage in the conduit t4 that at the time the pressure within the nozzle 32 is four hundred pounds per square inch, the ball 91 is dislodged to provide an additionalpath. for

the fuel through the passage 93170 the second", nozzle 91'. The pressure immediately drops to.

approximately one hundred pounds per square inch due to the added outlet and to another by.-

pass regulatorpresent-ly described. Abrupt'ly, the

fuel discharges from two nozzles at. a. supply Pres,- sure of; one. hundred. pounds per square inch. whereas immediately before it hadbeen discharging from one nozzle at. a, upply pressure, oi four hundred pounds per square. inch... Since nozzle 9i isabruptly fourgallons per hour dis,v

fuel' valve, communicatmg prouidedwi-th a valve seat. member 96. On this. is normally di posed a ball in! carry! This terminates near the ball 91.

amazes:

the two nozzles are substantially the' same size and since each of them discharges four gallonsper hourat one hundred pounds pressure whereas the first nozzle discharged eight gallons per hour at four hundred pounds pressure, the total discharge remains eight gallons per hour but the supply pressure is reduced to the originalvalue.

Because of the substantially similar characteristics of the nozzles, the transition in discharge from one nozzle at a supply pressure of four hundred pounds :per square inch to two nozzles at a suppiypressure of one hundred pounds per square inch is not particularly critical and is rather smoothly made, very little difference being detectable .in' the resulting combustion. While athereis some difference in fineness 'of atomization, still this is always above the minimum satisfactory .value,and turbulence of the air-fuel mixture makes this difference inconsequential.

iWhen. the demand drops and the second nozzle 91 is immediately cut out of operation by thereseating of the valve 9'! as the pin I04 is droppedand the ball 91 reseated due to-return of-the cam I4. The spring 6I being substantially at its previous position, the pressure second range surface I08 is rather abrupt andbecause of the spring pressure against the cam and because of the unbalanced pressure tending to hold the ball 91 seated, the cam does not tend to stay exactly poised between the first range and the second range conditions. Rathen'adjacent the transition point the pressure reacting on the cam changes so abruptly that the cam tends to remain either just on one side of thetransition point in its first range or just on the other side of the transition point in its second range. This property is permitted by a slight play or looseness or elasticity in thelever system especially in the fitting of the rod 83 so that in normal practice either one nozzle or two nozzles are in operation. There is nothing more than an instantaneous and harmless passage of the-system through the intermediate, transition position. The nozzles are not irregularly or unstably cut-into and out of operation.

-When two pass regulator is the cam surface 58 seated below 400 pounds persquare inch pressure while the unseating of the ballSI opens a parallel flow path to the second nozzle 9|. With the additional outlet open, the pressure drops below 400 pounds per square inch pressure and the first regulator closes completely and is therefore ineffective. To regulate the pressure under these conditions, there is provided a seethe leveris reversed-in its movement to reduce the: output,

nozzles are-in circuit, the first byinefi'ective. This is because- IUB holds the by-pass valve 0nd pressure regulator III in construction identical with the first pressure regulator and including a valve like the valve 58. The second regulator III has its own spring II2 supported by a screw I I3 mounted in a second cam follower III reciprocable between the chambers 63 and 66 in the base 26. The follower H4 rides upon "86 bya third earn.

nozzles 32 and 9| when they are both in operation. Their supply pressure is appropriately increased-from one hundred to four; hundred pounds per square inch. Because this surface III is entirely distinct from the surface 84 or from the circular surface I08, the characteristics of discharge of the two nozzles for an intermediate range of operation can be independently coordinated with the requirements of the system as a whole, especially the output of the blower supplying the combustion air. On-both sides of its range of effectiveness, the cam H6 is cir-' cular so that the valve holds its initial or final position. 7 I

The cam follower II I near the upper end of the cams effective range acutates a rod; H9 to unseat a ball valve I2I in the fashion the ball valve 01 is unseated. This permits communication from the bore 21 into a conduit I22 leading to a third nozzle I23 and through a branch conduit I24 to a fourth nozzle I26. The nozzles.

I23 and I28 are identical with the-nozzle 32-.

A single nozzle I23 of substantially double the rating or capacity of the remaining nozzles can be utilized but for interchangeability of partsit is preferred to provide two final The output of nozzles 32 and nozzles; 1

'-by a valve mechanism I2? identical, with that of the regulator valve '58. It is operated by a spring within the base 26 between the chambers 63 and I32 fast on the shaft I6. The efiective regulating surface of the cam; I32 is illustrated-by the dotted line- I38 in Figure 3. Outside this range, the initial portions of the cam I32 are circular.

line I09 and a center line- I34.

The'transition from the second range to the third range is abrupt as previously described. in connection with the transition from the first range to the second range. Either two nozzles are operating at four hundred pounds per square inch pressure or four nozzles are operating at one hundred pounds-persquare inch pressure and the mechanism hesitates imperceptibly between such ranges. -As the lever I is moved to initial one hundred pounds per square inch value to a final value of approximately four hundred pounds per square inch. During this time, the the'regulator H2 are held closed:

valve 58 and 9I --at the final: :supply pressure of four hundred pounds per square inch, the pressure at which the valve I2 opens, is approximately double their initial output or sixteen gallons per hours. If, then,the

I28 responsive through an adjusting screw I28 to a third cam follower I31 reciprocated This cam is not effective a in the first range nor in the second range but is effective in a third range between the center:

pressure on all four of the nozzles, there is;

produced a total output of about vthirty-two gallons of fuel per hour, the desired-maximum.

This is accomplished-with a pressure range of four rather than sixtyefour, and'pby pumping only say five or ten percent more oil than atomized rather than up to eight hundred percent more oil than atomized.

This mechanism. can be added to with -as many units as necessary to cut additionalnozzles into the burner to produce as wide a range as necessary, each nozzleor groupof nozzles being added to the preceding, effective, ones and the pressure of the effective group beingboosted through a relatively narrow range and then dropped as additional nozzles are introduced. The-reverse processrta-kes place-as the capacity of the burner is reduced, certain nozzles or groups being periodically eliminated with; simultaneous pressure compensation.

While the set-up as described is effective for 'all normal operations; it is sometimes desired to :change the general ratio of fuel to air as an over-all adjustment rather. than individually changing portions of the-contour of the cam surfaces-,in addition to or in lieu of making adjustments bythe screws, such as H3 and I29.

A general adiustment'to compensate for different air weights at; different altitudes, for example, or wherea markedly different type of fuel is used can readily be accomplished by shortening or lengthening the rod 83 and thus simultaneously rotating the shaft 16 with respect to the lever 1.

In general we have provided a straightforward. economical means for meter-ing fuel in the desired amounts over a very wide range relatively without increasing the pressure unduly nor decreasing it below a minimum :atomizing pressure. The mechanismis capable of comprehensive and accurate adjustment and is readily adapted to the instantaneous requirements of operation and also to'the general environment changes normally encountered.

We claim:

1. A fuel burning system comprising a plurality of external combustion fuel burner nozzles, a variable speed fuel pump having a high pressure side and a low-pressure side, a fuel conduit connecting the high pressure side of isaid'fuel pump and said nozzles, a variable devicefor releasing fuel from said conduit to the low pressure side of said pump, a valve in "said conduit for controllin fuel fiow to one of said nozzles, an internal combustion engine'for driving said pump, a movable "controller for varying the speed of said engine and h'ence of 'sai'd'fuel pum and 'a conmotion to said controller for varyin said releasing device and for operating said valve inaccordancewith 'the position of said controller.

2. A fuel burning system comprising an external combustion fuel burner nozzle, a variable speed fuel .pump having a high pressure side and a low pressure side, a fuel conduit connecting the high pressure side of said fuel pump and said nozzle, a variable device for releasing fuel from said conduit-to the low pressure side of said pump, an internalcombustion engine for driving said pump, a movable controller for varying the speed of said engine, and a connection to said controller forvarying said releasing device in accordance with the position of said controller.

3. A fuel burning system comprising a first nozzle, a second nozzle, a fuel pump, a main fuel conduit connecting said fuel pump and said first nozzle, a branch fuel conduit connecting said mai'n fuel conduit and said secondnozzle, a first device openable in response to a predetermined high fuel pressure in said main fuel conduit for releasing fuel from said main fuel conduit, a second device openable in response to a predetermined low fuel pressure in said branch fuel conduitfor releasing fuel from said branch fuel conduit, and a valve for blocking and unblocking communication from said main fuel conduit to said branch .fuel conduit.

4. A fuel burning system comprising. a nozzle bodyhaving a fuel conducting bore therein, a

nozzle tip mounted on said body in communicationwith said bore,- a fuel conduit at one end connected to said body in communicationwith said borepa firstvalve. in said body for controlling fuel fiow through said-bore, said first valve having differential areas subject to pressure of said fuel,

afirst spring .for urging saidfirst valve closed,

' force of said second. spring gradually to vary the pressure of fuel insaid conduit above and below the values at which the differential areas of said first valve are effective to overcome said first spring.

5. A fuel burning system comprising a nozzle body, a nozzle tip mounted on said body, means including a long conduit for supplying said nozzle bodyand said nozzle tip with fuel, a valve insaid nozzle body adjacent said nozzle tip responsive to fuel pressures below a first predetermined pressure for abruptly preventing said fuel from flowing to said nozzle and responsive to fuel pressure above a second predetermined pressure for abruptlyv permitting said fuel to flow to said nozzle, and a cam actuated relief valve in said conduit remote from said nozzle body for gradually varying the pressure of said fuel from a pressure 'below said first predetermined pressure to .a presfuel from said supplying means to said second nozzle, and means for varying the'pressure of fuel supply bywsaid supplying means and for simultaneouslyholding said spring in a position corresponding to said maximum pressure.

7 A fuel-burning system comprising a first nozzle, -a .second nozzle, means for supplying .said nozzles with fuel :under pressure, .means for blocking the supply .of fuel to said .second nozzle, a first relief valve on said supplying means in advance-of said blocking means, a first spring urging said first relief valve closed against and fuel pressure, means for moving said first spring into successive positions correspondingly to vary the pressure of fuel supplied to said first nozzle, means for unblocking the supply of fuel to said second nozzle when said first spring moving means is in one of said positions, a second relief valve on said supplying means after said blocking means, a second spring urging said second relief valve closed against said fuel pressure, and means for moving said second spring into successive position correspondingly to vary the pres- .sure of fuel supplied to both of said nozzles and for holding said first spring in said one of said positions.

8. A fuel burning system comprising a first- ,nozzle, means for supplying fuel under pressure,

a first conduit for conducting fuel from said supplying means to said first nozzle, a first valve responsive to pressure of said fuel in said first conduit for releasing fuel from said first conduit, 4

means for gradually closing said first valve, a second nozzle, a second conduit for conducting fuel from said supplying means to said second unblocking said second conduit and for holding said first valve at said point, and a second valve responsive to pressure of said fuel insaidsecond conduit for releasing fuel from said second eonduit.

9. A fuel burning system comprising a first nozzle, means for supplying fuel under pressure,

a first conduit for conducting fuel from said supplying means to said first nozzle, a first valve urged toward open position by pressure of fuel in said first conduit for releasing fuel from said first conduit, a spring for urging said valve toward closed position, a second nozzle, a second conduit for conducting fuel from said supplying means to said second nozzle, a valve when closed blocking said second conduit, and a cam for increasing the force of said spring and for opening said second valve independently of said fuel pressure.

10. A fuel burning system comprising a first nozzle, a second nozzle, a conduit for supplying fuel to said first nozzle and to said second nozzle, means for blocking said conduit in advance of said second nozzle, a first pressure responsive device for releasing fuel from said conduit in advance of said blocking means, means for operating said first device for controlling the pressure of said fuel to establish discharge of fuel from said first nozzle at a predetermined rate, means for opening said blocking means to supply fuel both to said first nozzle and to said second nozzle, a second pressure responsive device for releasing fuel from said conduit beyond said blocking means, and means for operating said second device for controlling the pressure of said fuel to establish discharge from both of said nozzles at said predetermined rate.

11. A fuel burning system comprising a first nozzle, a second nozzle, means for supplying fuel to said first nozzle, a first device responsive to pressure of said fuel for regulating the pressure of said fuel supplied to said first nozzle between a predetermined low pressure and a predetermined high pressure correspondingly to vary the discharge of said fuel from said first nozzle between a predetermined low rate and a predetermined high rate, means for supplying fuel to said second nozzle, a second device responsive to pressure of said fuel for regulating the pressure of said fuel supplied both to said first nozzle and to said second nozzle at said predetermined low pressure to establish the total discharge of said fuel from both of said nozzles considered together at said predetermined high rate, and means for alternatively supplying fuel to said first device and said first nozzle alone or for supplying fuel to'both of said nozzles and said devices together.

12. For use in a fuel burnirig'system, a housing, a duct for fuel under pressure 'in'said housingfa cam shaft in said housing, a relief valve in said duct, a spring for said relief valve, a cam on said cam shaft for varying said spring, a nozzle conduit in said housing opening into said duct, a blocking valve for'con'trolling communication between said conduit and saidduct, and a cam on said cam shaft for operating said blocking valve.

13. For use in a fuel burnin system, a housing, a duct for fuel under pressure in said housing, a cam shaft in said housing, a plurality of relief valves in said duct, a nozzle conduit in said housing opening into said duct between said relief valves, a blocking valve for controlling communication between said" conduit and said duct, springs for said relief valves, and cams on said cam shaft for varying said springs in succession and for operating said blocking valve.

14. A fuel burning system comprising a first nozzle, a source of fuel under pressure, a first conduit for supplying said first nozzle with fuel from said source, a first valve for releasing'fuel from said first conduit, a first cam movable through'a first range gradually to close said first valve to a predetermined position and through a second range to hold said first valve in-said position, a second nozzle, a second conduit for supplying said second nozzle with fuel from said source, a second valve for admitting fuel to said second nozzle, a'third valve for releasing fuel from said second conduit, a second cam movable through a first range gradually to close said third valve to a predetermined position as said first cam moves through said second'range, and cam means for opening said second valve substantially as said first cam moves from said first range to said second range.

ROBERT L. HARRIS.

MARCUS 'LOTHR/OP;

REFERENCES CITED f The following references are of record in th file of this patent:

UNITED STATES PATENTS

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