US2190314A - Carburetor - Google Patents

Description

D. FIRTH CARBURETOR Feb. 13, 1940.

Filed Feb. I5, 1936 6 SheeyS-Sheet 2 Uff/a D. FIRTH CARBURETOR Feb. 13, 1940.

Filed Feb. s, 193e 6 sheets-sheet s Feb. 13, 1940. D, FlRTH l 2,190,314

' CARBURETOR Filed Feb. 3, 1936 l 6 Sheets-Sheet 5 D. FrRTH 2,190,314

CRBURETOR 6 Sheets-Sheet 6 Feb. 13, 1940.

l Filed Feb. 5,1936

Patented Feb. `13, 1940 ,UNIT-ED STATES- PATENT OFFICE Theiinvention relates generally to carburetors for internal combustion engines, and more particularly to a downdraft carburetor.

v Carburetors generally may be divided into two 5 general classes so far as the position -of the throttle relatively to the fuel discharge nozzle and intake manifold `is concerned.,l i. e.,-a-posterior throttle carburetor wherein thethrottle is positioned" behind the nozzle (between. the nozzle f and intake manifold), so that the nozzle is on the low suction side of the throttle, Iand an anterior throttle carburetor wherein the throttle is in? front of the nozzle (the nozzle is positioned intermediate the throttle and intake manifold),

` so that the nozzle or fuel .discharge device is `on the high suction side' of the throttle. .Each 'of the two types of carburetors has certainadvantages, and each has certain disadvantages. For

A example, therpostericr throttle carburetoris advantagleous inasmuch as the meteringiof thefuel is accomplished on thelow suction side of. the throttle, thereby makingit fairly. easyto calibrate the fuel dischargemeans for partthrottle mixtures. A disadvantage of the posterior throttle carburetor, however,v is due tothe fact that the throttle, being positionedy between vthe fuel discharge device and the. intake manifold, interferes with the flow of kfuel particularly for wide-open or full-power throttleposition, `thus causing poor distribution ofv the .fuel mixture to the cylinders. For this reason' the. anterior throttle carburetor isirnore advantageous so'far as wide-open or full-powerthrottle position is concerned, since the throttledoesnot interfere with the flow of fuelv mixture. However,;beoause of the location of the fuel discharge devicev in the high suction zone of an anterior. throttle. ,carburetor, minute changes in ther orifices. orfjets of the fuel discharge devices causes. considerable change in thev mixture ratio. The present' invention constitutes an improvementlin the :form of carburetor disclosed in. my copending application Serial No. 726,059, filed May 17,1934.

It is an object of thev present invention to prol vide a new and improved carburetorembodying certain advantages of both the posterior and the anterior throttle type carburetor, andA at the same time eliminate disadvantageous features of yeach which were heretofore pointedl out.l

Another important object of the .present invention is toA provide a carburetorofthis rtype embodying new and improved means for increasadjustment is interrelated to and governed by the" setting ofv the choke valve.

`Another object is to provide a new and improved carburetor having apluralityof accelerating pumps .conneoted -into the .main air and fuel passage of thecarburetor in` such a manner as to insure proper andeftioient mixture vof the fuel and air.

Another object .is to provide a carburetor wherein Aa throttle member having a .main fuel.

discharge port at one of `its edges is arranged to cooperate with an emulsion tube in the `main, air and fuel passage to'deliver an efficiently vaporized fuel mixture.y

' Another object is to provide a carburetor having'an improved and simplified. constructionproviding an accelerating pump having .a delayed fuel feeding action.

. Another object is toprovide a carburetor having. a new, improved and simplied ,idling fuel supplymeansp Another `objectis to. provide a carburetor .having.. an,ew and `improved casingv construction whereby manufacture, assembly,l inspection and repair are facilitated. v

. Other objects andv advantages will lbecome 'apparent fromthefollowing description, taken in connectionwith the accompanying drawings, in Whichl v Fig. 1Y is a vertical central section Vthrough a preferredA,einbodirnentI of. theinvention, showing the throttle inl a partially open position.

, Fig. 2 is` ,an inside view o f lone ofthe members which form, thefuel chamber. t

Fig.- Suis an enlarged vertical 4sectionalV view taken substantially along theline 3--3 of Fig. 1.

Fig. 4 is an elevational rView of the float chamber with the. Side. member 0f the yfloat chamber .removed andwith. a portion 0f the .fuelsupply member showndin central `longitudinal section.

1 Fig. 4a is zalsectionall vview of the Afuel feeding member showing thechecl; valve formation.`

` Fig. 5 is a view similar to Fig. 4 taken substantially along the line 5-5f0f Fig. 1V and showing onevf the ,aceleratinervmps l 5f? is a plan view of a kretaining washer shown in Fig.. 5. y n Fig. 6 is afrontelevational View of the carburetor.

g Fig. '7 is a top plan view-of the carburetor.

Fig. 8 is ya side velevational View Iof -the carburetor asseen, from the right in Fig.,6.f

Fig. 9 is a ,verticalv sectional viewptaken substantially'alonggthe line 9-9 ofY Fig. '7 and'v illustrating a preferred formuof idling fuel supplyjet. .Fig. 101s an enlarged sectional View, taken longitudinallyalong the axisfof: the throttley member and illustrating the vacuum controlled means for everninathelfuel Supply.-

f ;.Fievv 1 1.15 a @View Showing-e1? elternriveferm of carburetor, a portion of the View being taken in vertical section through the rotative axis of the throttle member.

Fig. 12 is a view similar to Fig. 4 and illustrating in the fuel chamber an accelerating pump having an alternative form of actuating means. A

Fig. 13 is a sectional View similar to Fig. 3 and illustrating an improved means for adjusting the' idling speed.

Fig. 14 is a diagrammatic view showingthe relative position of the parts in section.

While the invention is susceptible of embodiment in many different forms, there is shown ciples of the invention and is not intended to` limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

In the form chosen for disclosure herein, the invention is embodied in a downdraft carburetor having a body It having a tubular portion I5 forming a main passage I5, with a flange II on the portion I5 at the lower end of the passage I6 for connection with an intake manifold, and providing a fuel chamber I8 at one side of the passage I5. Preferably the fuel chamber I8 is formed in two sections I3 and I8, separable along a vertical plane, with the section I8 vcast integrally with the tubular portion I5, and with the section I8" clamped in place against an interposed gasket I3 by means of screws 2IL` Adjacent the upper end of the passage I5 a choke valve 2l is mounted on a rock shaft 22 for actuation by a conventional arm 23 on one projecting end-of the shaft.

In the passage I5 below the choke valve 2|, there is provided a throttle member 25, mounted on atubular rock shaft 26 which is parallel to the shaft 22 of the choke valve. The location of these shafts is such that the axis of shaft 26 is perpendicular to the plane of separation of the fuel chamber sections I8 and I8, and one .end of this shaft projects through bearing 21 into the upper portion ofthe fuel chamber I8 as shown` in Figure 1. At its .other end the shaft 26 projects through a bearing 2B in the tubular portion I5 and carries at its outer extremity a conventional -actuatingarm 29.

Fuel is supplied to the fuel chamber I8 by a suitable conduit (not shown) which may be connected to a bushing 30 which is threaded through a boss 3l on the removable section I8 into the interior ofthe section as shown in Figure 2. vThe boss 3i) is preferably located so that the bushing axis is horizontal and parallel to the plane of separation of the sections I8 and I8, whereby the carburetor may be fitted for either right or left-hand mounting merely by provision of differently formed sections I8. Slidable in the bushing 30 is a valve 32 which, by means of a float 33, is governed to maintain the fuel in the chamber I3 at substantially the level indicated by the line 34. Preferably the float is mounted ona lever 33 which is pivoted on' 'a pin 33 carried by the member I8 so as to be positioned withinv and carried bythe removable member IB" and to move in a plane parallel to the plane of separation of the sections I8 and I8".

In they preferred form of the invention, the fuel discharge means comprises a fuel duct or port 35 formed in the throttle 25, the port 35 communicating at its inner end with an axially extending passage 36 in the throttle shaft 25.v Y The passage in the throttle shaft extends into Y the portion of the shaft which vprojects into-the upper end of the fuel chamber I8 as shown in.l

Figure 1. Various means may be provided for supplying fuel from the lower portion of the fuel chamber to the port 35, although preferably such means assumes the form of a fuel feeding member 40 secured to the throttle shaftv 25 so as to swing therewith, the member 40 havinga passage therethrough connecting at one end with; Y v

the passage 36 and at the other end with the surface of said member below the fuel level in the chamber Itas hereinafter more fully de-`r` scribed, to form an inlet.

In the form illustrated in Figuresll to 10, avv tubular fuel feeding member @Il is secured to thel projecting vend of the shaft 26 adjacent tothe bearing 2'I and extends radially from the shaftldown into the fuel chamber I8. AsleeVe-like piston 4I, slidable within the member iti), has its lower end spanned by a wall 32 through which an axial bore 43 and an intersecting transverse bore 43' adjacent the lower endy provide a por- The fuel inlet pastion of a fuel inlet passage. n sage also includes ka metering port M in a bushing I5 within theupper end of the member 40 (Figure 4), an openingv 46 in the upper end ofv the member 4i), and a registering port 4I (Figure 1) in the shaft 26 which opens into` the passage 36. formed by the member 4I) to form an accelerating pump, the piston being moved upwardly during opening movements'of the throttle'25 by meansof an arcuate cam member IIB mounted The piston 4I cooperates' with the cylinder in the lower portion of the fuel chamber section I8'. The piston 4I atitslolwer end rides on the cam, member 48 so that during swinging movement of the throttle 25 and its shaft 26 (in a clockwise direction as vshownjin Figure 4) the piston is Ymoved upwardly or toward the axis of the shaft 2E'. In the idle position of the throttle 25 as shown in Figure 4, the piston is projected or withdrawn to the lower portion of the mem-'1 y ber 4U. An expansive coiled spring 49 positionedV between a shoulder' 50 on the bushing l5 and an apertured washer 5I acts, through the washer 5I`and`an'interna1 shoulder 52 against which.

it bears on the pistonk III, to move the piston 4I downwardly and maintain the lower end thereof in contact with the cam 43. y

In order to prevent return Aiiow of fuel from..

a disk-type the accelerating pump cylinder, check valve 53 is positioned in the lower portion of thehollow piston II so as to 4be adapted to close the port 43 during upward movement of the piston. This check valve is vof Ysufficiently light weight so astobe normally raised by incoming fuel and held in the position shown in Figure 4. Preferably a metering pin 5d is carwill first be positionedinl the'port 44- so as to enlarge the area of the port and pass increased quantities of fuel and finally the reduced portion.

55-"will;:be positioned in the portjM .soias.;toi.give the maximum elfectivenesst.y The "metering-pin vmay assumeA various forms depending upon the characteristics desired'. j.

More-.eflicient proportioning of' the. fuel mixture in the higher speed ranges is obtained in the present embodiment of the invention vthrough the provision, in cooperation with vthe metering i action of the fuel supply member 40, of a vacuum controlled fuel'metering means which is prefl erably mounted in the shaft 26 and governs the` eifective area of the passage 36,.. .This means in its preferred form is illustratedin Figures 1 and 10, andlcomprises a metering port 60 formed in the passage 3bl adjacentA its junction with the port ofrthe throttle.v l

Themetering port 60.is controlled' by `a relatively small metering pin 6I which extends axial-A ly through the port 66 from a piston 62 whichv isfslidably mountedfin a cylinder'portionL 62 within-.the shaft 26,and beyond thefport 35 (see FigurelO)- i handend ofthe pin-6I lies within and-'reduces the effective area of. port 'when the-piston 62 is in. its right-hand position,` while movement ofy the piston to the left'projects the head 63 a substantial distance beyond `thelport 6I)l and increases its eifec'tiverarea. The-.piston 62 moves between limits. fixed vron the left byfa shoulder 84 and on theA right by a ,sleeve 65threaded into the shaft, and anexpansivecoil spring v66 ex-` tending through the sleeve andacting be#rv tween an end plug 61 in theshaft 26and1the piston 62. serves to.y urgethe meteringv pinBI.. to the left so as normally to provide the maximum.

effective are'a for the metering port 6I). .If de'.

sired, a guidepin 68 may extend from v.theplug 6'! through Athe spring 66. To `obtain vacuum.y controlled actuation of the piston 62,:a passager 69 formed inthe throttle 25 and the 'shaft 26, and extending in thesame directionasftheport 35, is connected throughan annular groove 10.. and a port .1I to theright-hand .end ofv cylinder j 62. When the piston 62 is in its .right-.handlpoi sition of Fig. 10, an annular groove. 62? therein registerswith a vent passage 62e' tothe low suction sidel of lche throttle 25 soasito .preventnow.` ofA fuel past the. piston. 4Thus the normal fuelx: mixture is proportioned efliciently throughout' the range of speedsby the cooperative actionof the metering pins 54 and GIL'whichare controlled respectively bythe throttle position and the vac uum conditions in the motor.

SinceA there -is always a passage of. fluid i through the port 35,l :the effectofthe suction in lthe passage I6 will be lower on thefleft side than on the right side of the pistonl 62 .for theireason.

that the right side is a dead end.r A differential pressure is thus set up which accounts. for the resulting movement. of the `piston..62;y i

`For, purposes of 'sudden'acceleratiom the...V`

pumpingvaction of the fuel supply member 40 acts, of course, to forcefuel rapidly through the.

metering port 44,. which is openedhto vits greatest extentby the advancingofritsmetering pin-S; 54,

and this additional fuel passes freely-' through of'fuel through supplying' further. fuel at such a point in the main passagel'i-.a's toin'sure` thorough `and eiiicient mixture. offall. of the.. fuely Anhenlarged headr63 in the left? in Figures 1, .5 rand* 9, and comprises a pump 'I2 arranged: for actuation by the-shaft 26 of the throttle 25. In the form shown the pump I2 has a cylinder 'I3 formed integrally within the section. I8 radia1ly withrespect to the shaft 26 and having a piston 'I4y therein adapted for actionbyfa cam 'I5 `fixed to the shaft 2l intermediatethe fuel supply member 4I) and the bearing/2l. rAt its lower'end, on the outside ofthe section I8', the oylinderis closed by a threaded plug 16', and above this plug fuel is admitted to a threaded portion 'I'I of the bore which forms the cylinder-,through an inlet port 18. `Above the port 18j'inthe'portion 'I'I of the bore is threaded a plug I9 having an axial. passage Bil'l therethrough. opening into the space immediately below the piston 113. In the passage 8D is locatedta ballr vcheck 8| `held against undue upward displacement from its seat 82 by a spiderlike-washerf;83. A spring Silbetween the washer and the piston I4 normally projects the piston 1,4', and alsotservesto hold the washer 83 in. p0- sition.` y' s When the piston 'Mis depressed by actuation of. the throttle. 25', the fuel trapped in the cylinder byfthe check valve 8 I. is forced upwardlythrough a ypassage 65. (Figs. 5 and l9) into a. chamber 85 (Fig. 9), through an orifice or jet 8'I and thence 0 outi of adisch'arge nozzle or jet 68 intothepassage` I6. Preferably such discharge is somewhat transversely of the passage just belowthe level of: the throttle 25. n

After the contents of the .pump .'12 is dichargcd, further ow of fuel past the checkvalve Si is preferably` prevented while f the` wide-open throtu tle' position ismaintained. This end is attained by a spring plunger 9i? slidably mounted axially inv the' piston 'I4 and. projecting downwardly therefrom solthat in the discharge stroke ef the.

piston the endof the plunger. 95 passes through the spider-like'washer 83 topress the ball check member 8|.y to its seated position. A spring el, surrounding the plunger Within an enlarged bore 92e in the piston 74, acts against a. flange 93 on the;plunger ,9G tourge the'plunger to its projected. position as limited by abutment of the ang'ezwith a bearing Washer till whichsurrounds the plunger and isiixed in closing relation tothe lower end of the bore 92. A reduced continuation. 95=1of the bore62fguidesthe upper end of thecplunger 90.

Ther fuelfor idling. purposesfis' in the present embodimentsuppliedy by means which includes the vfuel passages through the'acceleratingpump 'l-2rto the discharge nozzle 68.I An adjustable primary air. supply to the nozzle 88 isprovided for idling lpurposesby a horizontal bore 96 .extending through the member I5 into the passage I8 above the level' of the throttle 25, with a Vertical bore 9.7 connecting the bore'll into the passage between' thejet S'Iand the nozzle 88 (Fig. 9). An adjusting screw .98 threaded into the bore 9d, andheld in Yadjusted position by a spring'li, cooperates Wththe-inner surfaces ofthe bores 96.and9to varythe effective area of therpassages. By removal of a plug in the chamber 86, 'the jet, 81 may be changedto vary the size of. orifice, andthus by meansfofrthefjet. Si and theradjustment of screw 98, both thequantity of fuel 6and.qualityofifuel mixture may be adjusted.

. The. present. invention las embodied in-jthe 'form illustrated -fin-uFigures. 11 to lll' preferably provides meansv whereby an increased Y idling.. speedis. ob-

`withtheair passing'throughpassa'ge I6' This cooperating fuel* supplyy means. is best illustrated tained during use of the choke valve2|.- Thus,

as shown in Figures `1,621.7, and 8,.a vertically shiftable stop member |Il|I is mounted in. such a position that the idling position of .the throttle 25 may be governed by. a plurality of stop shoulders |62, |63 and |04 formed on the stop member. In the form shown the stop member |0| has a lower yoke |65 slidably embracing shaft 26 between the bearing 28 and the arm 29, and a parallel upper yoke IE6 slidably embracing the shaft 22 between its bearing 'and a retaining washer IIll at the end thereof. Formed as a continuation of the throttle `arm 29 is an arm |08 carrying an adjustable stopv screw |09 adapted for .selective engagement with the vstop shoulders in accordance with the vertical setting of the stop member It.

When the choke 2| is closed, la radial arm ||Il fixed thereto engages a lug I I. on the yoke |06, so as to raise the stop `member toward its upper position of Figure 8, with the result that stop shoulder |56 is effective and a fast idling speed is obtained. When the choke 2|' is opened the stop member IIlI drops to its lower position so that stop shoulder |62 is effective and the normalv idling speed results. In the use of this device, the throttle 25 shouldbe opened as is doneyby most drivers in starting, thereby facilitating the elevation of the stop member IUI. This cooperative action of the choke and the throttle is of particular advantage where an automatic choke is employed, although its usefulness is not limited to such constructions.. The relative position of the working partsk ma be seen in the diagrammatic view of the device shown in Fig. 14. The tubular portion is shown on the right forming the mainpassage I6 and on the left is'the casing I3 which encloses the fuel chamber I8. Located in they passage |6 is4 the throttle 25 secured to the throttle shaft 26.

with which it rotates. The shaft 25 extends into the fuel chamber I8 wherein the fuel feeding member 40 is attached to it. When the shaft is rotated by means ofthe actuating arm 29, the throttle 25 is moved between. o and on positions and at the same time the fuel feeding member Ml is swung from one position to an-r other within the fuel vchamber I8. Integrally attached to the casing of the fuel chamber I8 isv the pump l2, the outside of which is formed by the cylinder 13.

Fluid enters the fuel chamber past shown dotted at 32, and lls the. chamber to a level 34 where it is maintained by a float mechanism, omitted from the diagrammatic view of Fig. 14 for the sake' of clearness, but which is shown in detail in Fig. 2. Fuel from the chamber passes normally vthrough the axial bore 43 of the fuel feeding member 6U, thence upward through the opening 46 into the passage 36 which lies centrally of the shaft26. ducted through the metering port and thence outward and downward through the port 35 of the throttle into the passage I6.

When the throttle is closed, fuel for idling purposes is drawn from the fuel chamber I8 through the port "I8, past the check Valve 8| and thence upward through passage 85, from which it is drawn downward and outward from the discharge nozzle or jet 88 into the passage I6. A quantity of air which is drawn through the bores 56 and S'I around the closed throttle unites with the quantity of fuel drawn through the jet 8l into the passage lI6 to form a combustible mixture for idlingpurposes.

the valve the discharge end lof the bore.

Fuel is then con-y when thethrotue 25 operiedga sumcient y' amount, an additionalchargeof fuelissent into i the passage I6 byzineans ofthe pump 12. To

produce this added charge,- the cam. 'I5 fixed to" the shaft 26 drivesthepiston .14 downward by which action any quantity of fuel trapped below it within the cylinder I3 is forced upward and outward through' the passage 85 and nozzle 88` N l' y into the air passage I6.

In the embodiment illustrated inFigure 11 of,`

the drawings, the. invention is embodied in a carburetor constructed generally along ythe lines of the embodiment of-'Figures 1 to 10, but with the fuel feeding member 4i) serving as the sole. ,151 In thisiform,the vpiston andy cylinderk 1 of the member 40 are made of a greater diammeans 'for providing a rapid feed for accelerating purposes.

eter so as to increase the capacity thereof,` and an and supporting lug secured to the tube H5. By the use of the emulsion'tube I I5 suspended relatively close tothe` outlet port 35 of the throt-k tle, the relatively large quantity of fuel fed through thel port 35 is properlyA directed and mixed with the air as it passes through the car-V L.; y, 3o f,

bureting passage.

With the form of accelerating pump or fuel feeding member 40 employed in either of the embodiments disclosed, la prolonged feeding action bythe pumpmay be obtained through the provision of a resiliently mounted cam' 48' asA shown in Figure l2. In this form, the cam 48 is pivoted on a screwy |20 at the end which is enf gaged by the piston 4| in the closed position" of the throttle. "At its otherend, the camis guided for pivotal movement by a slot |2| through which a screw |22 extends, and beneath this end of the cam an expansive coiled spring |23 is positioned roll' about'a depending lug |24. Uponquick opening of the throttle' 25, the cam 48 is depressedsoas to compress the .spring |23, and by making the spring |23 slightly stronger than the `spring 49 of the pump, the cam 48i`s gradually elevated so as to cause a' prolonged discharge fromthe Dumpk i.

To provide an idling supply'of fuel, the embodiment of Figurev l'lpreferably utilizesthe main fuel supply passages jfromthemember 45,'and to this end, as shown in Figure 13, an''idling fuel discharge oriflce1|26 is .formed in the throttle 25lv from4 the bore of the" port 35. downwardly through thesid'e of "the Vthrottle which facesv downwardly in the closed throttle position.

Preferably the orice |26 is located adjacent to shown in Figi 13, an adjustable passage for air is preferably formed about the edge of the throt- With the funn so tle adjacent tothe port 35, for the purpose of regulating the richness `of the idling mixture'.`

Thus a threaded bore |21 is formed in the wall I3 so that the 'upper Aand lower edges of the bore are located above and-below `they throttle faces,

and bymeans of a screw |21 threaded throughy the` bore |21 an adjustable by-p-ass is formedv to vary the amount ,of air drawn ypast Said kedge'ffy To effect an adjustmentlof theidling' mixture, the screw |21 is screwed outwardly tof."

permit the throttle valve to shut tighter thereby to reducethe open space at the edge cutting down 45 for fuel the passage of air rin order to produce a richer mixture. The screw l|21 is screwed inwardly to prevent the throttle valve from shutting tightly thereby increasing the opening for air to produce a leaner idling mixture.

In the various forms illustrated'herein, the fuel feeding member 45 is provided with an irregular opening 43|! through which the reduced and flattened end |3| of the throttle shaft extends. A cap nut |32 is threaded onto the end ofthe shaft 26 so as to clamp the fuel feeding member against a shoulder on the shaft formed by the reduced portion |3|. Thus rotary movement of the fuel feeding member with the shaftis insured. Preferably, as illustrated in Figures 1 and 11, a groove |33 is formed inthe shaft intermediate the ends of the bearing 21, and a ventv |34 (Figure 5), or a vent |35 (Figure 11), is provided in the body member-so as to prevent any syphoning of fuel through 4the bearing should leakage occur. Additional vent means is also provided for the fuel chamber |8, and such means may take the form of .a bored passage |36 (Figure 11) between the interiorl of `they casinglsection |8' and the upper end of the passage I6, or it may be formed by an lup'standing' sleeve |31 extending through and riveted to the top of the removable section |8".r

On the top of the sleeve |31 is secured a depend- .ing `skirt |38 which shields the vent openings downwardly in the body passage asthe throttle is opened,'the fuel head on the orice may be varied, and if desiredthe orifice may be moved from a position above the normal fuel level in the fuel chamber to a'position below the normal fuel level.. By locatingthe discharge orifice in the throttle a simple construction is obtained, and as the throttle is opened'the fuel discharge orifice moves downwardly vwith the incoming air so as to provide aprompt response to the demand By'securing the fuel feeding member to the throttle shaft soxthat it swmgs therewith, there are no movablejoints inthe entire fuel supply passage Wheredetrimental leakage could occur. Furthermore, the fuel supply passage is effectively protected from the heat of the engine,

the portion in the lthrottle shaft and throttle the normal fuel feed. l

The vfuel' supply means provided is obviously such as to give eflicient and economical performance, and in, every embodiment is particularly adapted for economical manufacture.

It is believed to be apparent that the form and construction o f the fuel supply chamber provided by the present inventionis `such as to simplify Byy and reduce the costl of manufacture ofthe carburetor as a whole, and in addition, it facilitates the inspection of the various operating parts of the fuel supply means. The present formA of casing provides' for the fixed mounting of the rone pump .12, as well as for the positioning of the member llt within a rigid portion of the chamber lll so as to be housed and protected thereby while being readily accessible for inspection or repair. in addition, the float land the :supply connection are associated with the removable section so as to facilitate such inspection .of the other parts, and in such mounting the float is fully housed and protected. l By reason of the relatively large area capacity of the passage 3&3, andthe location of the metering port tu relatively close to the discharge oririce the opening of the port 60 by operation vof its vaouuincontrolled metering pin results in an instantaneous increase in the fuel feed, whereby to render the motor more responsive. l

orifice, means for supplying fuel from said chamber to said main passage, said means comprising a pair of accelerating pumps supplied from said chamber and operatedto discharge fuel in repumps being connected to discharge through said orifice, and the-other of said pumps being connected to discharge at another point in said `main passage.

2L A carburetor f comprising, in combination, a body providing a main passage and a l fuel chamber, a throttle in said passage having a fuel passage rformed therein terminating in a' clischarge port adjacent to one edge of saidthrottle, a shaft supporting-said throttle and having one end .projecting into said chamber, said end having an axial bore therein connecting with said fuel passage, a fuel feeding member projecting substantially radially from said end of said shaft and arranged'for swinging movement therewith, said member being arranged for feeding of fuel to -said bore, a separate idling fuel supply means fed from said chamber, an accelerating pump 1 said chamber, arranged to discharge through said idling fuel supply means, and a cam on said end of said shaft for operating said pump.

3. A 'carburetor comprising, in combination, a body having a mainpassage and a fuel chamber at one side thereof, a throttle in said passage having a fuel passage therein terminating in a clischarge' orifice, a rock shaft supporting said throttle and having an axial bore forming a continuay tion of said fuel passage toward one end'of said shaft, said end ofthe shaft projecting into said chamber, lan accelerating pump mounted on said end of the'shaft to discharge into saidl bore and `to swing withr said shaft, means to operate said pump as it swings in the opening movement of said throttlej af second accelerating pump mounted in a iiXed position in said chamber, said second pump being arranged to discharge into' said main passage, and a cam on said shaft for operating said .second pump.

' DAVID FIRTH.

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