US1390681A - Carbitreter - Google Patents

Description

S AT S? PATENT OFFICE,

I WILLIAMVA; EDWARDS, or CHICAGO, ILLINOIS, Assrenon TO STEWART-washes SPEEDOMETER CORPORATION, OF CHICAGO, ILLINOIS, ooi-ttrona rion or VIB- Be itknown that I, iterati A. Enwiiizns,

acitizen of the United "States, residing at Chicago, in the county of Cook and State 5 of Illinois, lHIVQ lHVOIltGCl certain new and useful"Improvements in Carburetors, of

hing-conditions. It consists in the elements and features-of construction. shown and described-as indicated in the claims. i

In the drawings: i I I 'l igure l'is anaxial section: of a carburcterembodying,thisinvention.

Fig. 2 Fig.1. w v

Fig. 3 isaibottoin side'yiewof the same. ai'lhe :carbureter shown: in the drawings comprises a liquid fuel supply chamber, 1,

haying: connections through a plug, 1, at:

the; top with a source of liquid fuel supply and means for controlling-this supply to pic-vent overflow or flooding by means ofla float 6 in the chamber operating thevzcontrolling valve, l",-in a manner well understood and requiring neither particular illus- I which is at a considerable distance above tration nor description. Tlie-body of the liquid fuel chamber, 1", isipreferably formed integrally-iwith the Venturi tube, 2, which extends axially through the'said 'liquidfuel chamber reducing the latter to annular formas to its liquid-containing space,-sa1dannu- 40 ilar' chamberbeingclosed at thebottoin by" airemovabl e cap, 3, which affords convenient access to the parts within thewliquid chamber fortheir insertion and adpistinentj and repair. The main Veiituri tube begins to c'on- V verge toward itsthroatv or most constricted part, atthe-top of the float chamber, and

therefore at a considerable distance above the top of the level-governing float-,6, atkits highest position, which :is of course ,above the governed level of-tlie'liq'uid supply in the chamber. lVithin the nainYenturi tube,

2, there ispositifoned a inouth piece, 4-, 00- axial w th the main Venturi tube'and pref- I erablyitself in the form-of a Venturi tube and hereina ter referred teas. he uxiliary isa section atthe line, 22, on-

QARBUR TE I I Specification of Letters Patent. Patented Sept. 13, 1921. l Application filed November 23, 1918. Serial No. 263,799.

Venturitube or Venturi inouth piece. This mouth piece,'-- 4, is positioned and secured within the main Venturi tube by having at its lower end three radially projecting ribs, 1 constituting a spider by which the Venturi mouth piece is centered in the main Venturi tube, which is counter-bored from its lower end to form a shoulder, 52, against which the said radial spider projections of the Venturimouth piece or the ring, r connecting them, are stopped at the upper end, a circular spring key, 5, beingengaged in a groove 2, formed in the interiorwall of the lower part of the main Venturi tube for stopping the V enturi mouthpiece and retainingit 1 with, its spider stopped against the shoulder, 2. The liquid issupplied to, the mining chamber, or spac'e'in the Von t'uri tube=inwhich vitis intermixed with-air, by a duct which comprises a pipe, 7, depending from a fitting, 8, which is screwed into the top' of the liquid. fuel. chamber and which hasa reduced: orifice, 8-, leading througl'i it for vconnection with a small pocket, 9, formed inthe web of the castingwhich constitutes the top ofthe liquid fuel chamber,

from which pocket a tube, 10, extends across the annular space between the main Venturi; tube, 2., and the Venturi inouth piece, 4, into which said tube 10', is screwed at its inner end, so that the duct formed by the tube dis- 1 charges in the mouth, piece passage at, a point alittle above the constriction thereof the goi 'erned level of the liquid supply in the float;cliainber,'6', as indicated. A throttle valve, 12, iis positioned. in the Venturi tube, 2, thatisto say, in the passage leading to the engine intake, at a point considerably beyond theconstructio of said V enturi' tube, and asillustrated at a point Just beyond the tapered portion thereof; From the pocket, 9, a'duct, 11, forinedin anexten sion of. the integral casting'which constitutes'the Venturi tube-and the body of the liquid fuel chamber, leads back ,iiito'the engine intake passage the extension of the Venturi tube passage-entering the same pistbeyond the pointof seating ofthe throttle valve; Preferably the discharge of this duct in the engine intake passage beyond the throttleyalve is restricted by neans of a plug, 13, which is inserted through a hole bored in the boss, 1:1, whose end isafterwa-rd closed by 'afplug, 16, said restricting plug,

ll Q

13, having the passage formed axially through it substantially of the same diame ter as the passage, 8, and as the axial pas vided another duct, 15, formed in the casting leading from the upper part of the liquid fuel chamber into the main Venturi tube into which it opens at a point approximately in the'transverse planeof the discharge mouth of the Venturi mouth piece, a little beyond the constriction of the main Venturi tube.

The operation of the device above de scribed is as follows:

lVhen the engine is idling, the throttle valve, 12, being closed as shown in Fig. 1,

and some leakage of air occurring past that valve. which is intentionally made loose fitting in the passage in which it is located. the suction of the engine will lift a limited amount of liquid fuel from the fuel chamher, 1, through the continuous passage formed by the ducts, 8 and 11; but by reason of the absence of any substantial air current through the main Venturi tube, no liquid fuel will be drawn tl'irough the tube, 10, leading from the pocket, 9, into the Venturi mouth piece; but on the contrary, air will be drawn in through said Venturi mouth piece passage and through said tube, 10, into the pocket, 9, and mixing with the liquid fuel passing through that pocket will pass up through the duct, 11, and be discharged with the liquid fuel',a partial mixture of air and liquid fuel,into the engine intake passage beyond the throttle valve, where it will receive a further admixture of air passing around the throttle valve, thus affording a suitable mixture for serving the engine idling or with-very light load. When the engine is to be connected for carrying load, the throttle valve being open, the suction of the engine producing an inward air current which will have a high velocity at the constriction ofthe main Venturi tube, produces by entrainment, 111 addition to the suction, a rapid inrush of air through the Ventur1 mouth piece, the velocity of which Wlll be maximum just be yond or inward from the constriction of the In addition gine by taking in a largely increased amount of air before there is time for the suction to pick up the liquid fuel, lifting it from the chamber, '1, through the pipe, 7, and ducts, 8 and 10. The lag as it is commonly called, of the liquid fuel, might be diminished by making the passages larger and thereby more free and by making the governed level of the liquid in the chamber, 1', higher; but when this is done so that the engine is not actually starvedin the first strokeafter opening the throttle, a greatly increased flow of liquid results, as soon as the lag is passed, in too richa mixture causing'diminished efiiciency or total stoppage,-

which is liable to occur immediately'following the first stroke or two. Both the starving and the over-enriching are prevented by the structure shown; The suction having been operating through the duct in the plug, l3,-and pipe, 11, for lifting the liquid during the idling of the engine, the liquidwill be already standingin the duct, 7, and in the chamber, 9, ready to enter the duct, 10, before the first experience of suction through the vacuum tube results from opening thethrottle valve and substantially full atmospheric pressure being, for the instant, operative on the surface'of the liquid in the chamber, 1, the liquid willrespond to the suction about as quickly as the air responds, and the first charge drawn in after the opening of the throttle will be an effective mixture, and not a starvation mixture because the liquid is already in the pocket, 9, and the reduction of pressure on the liquid in the chamber, '1, which will eventually result from the suction operating through the duct, 15, will not have been experienced'for an appreciable interval after the first stroke or two of the eng1ne,t o a degree sufficient to defeat the in-fiow of the suction upon the liquid already lifted in the duct, ,7S, and into the pocket, 9, and the duct, 10. In the immediately succeeding strokes of the engine, however, the suction operating through the duct, 15, counteracts the tendency to an over-rich mixture by affording an avenue for the suction which results from the comparatively high degree of partial vacuum existing in the main Venturi tube at the point justbeyond its con s'triction, reducing the pressure upon the liquid fuel in the fuel chamber balancing the suction operating through the Venturi mouth piece tube a duct, 10, and causing less liquid to be sucked in by that passage than would be the casegif there were not pro vided any means for reducing the pressure upon the liquid in the liquid fuel chamber below atmospheric. Thea'esult prompt acceleration or picking up of speed by the engine under load upon opening the throttle valve without a succeedingloss from over-richness. lVhen the engine is is very v stricted duct in'theqplug,"13,'for taking a proper quantity of liquid ffuel beyond-' the throttle valve V y 4 lVithout regard to the effect of the duct, 15, for the purpose described, the Venturi form of the month piece passage is important for two reasons, first, because being tapered widening from a point below the level of constriction of the main Venturi tube to greatest diameter approximately at passing the mouth of the Venturi-shaped mouth piece, tends to produce a stronger current through that mouth piece passage,

7 which in turn has its highest velocity at the constriction of said Venturi mouth piece passage, thereby exerting the maximum enpiece passage, which prepares it for more thorough mixture than would otherwise re sult when it emerges from the wide discharge mouth of theVenturi nozzle into the high velocity air current passing through the main Venturi tube at the constriction of the latter.

It will be observed that the velocity of the air passing through the main Venturi tube at the level of the discharge mouth of the Venturi mouth piece and of the duct, 15,

i will be less than the velocity of the air passing the discharge mouth of the tube, 10, just above the constrictionof the Venturi'mouth piece passage, because the effect of said Venturi mouthpiece passage is to give an increased velocity to the air at its constric tion; and this high velocity, it will. be observed, produces a stronger suction at the discharge mouth of the tube, 10. in the Venturi mouth piece passage than that which is producedvthrough the duct, 15. It will be also observed that it is necessary that there should be a greater suction at the' first fm'en-' tionedpoint "than" at' the second, since" it is only by virtue of the diifere'nce 'in suction and the resulting difference inpressureupon the 'liqu id in the liquid supply chamber tha't the "l'iquidfuel'will be lifted from the liquid fuel supply 5 chamber for discharge through the" duct-Q10, and admixture withthe air as described; and itis primarily for producing this difference in suction at the two points that the mouth piece passage is made of Venturi form as described.

1. In a carbureter, in combination with a liquid fuel chamber and liquid level governing means therefor, a main air supply passage open at one end for air iniet, and adapted for connection at the other end with the engine intake, said passage being constructed for causing reduction of pressure to result at a predetermined point therein from the air currents therethrough; a fuel inlet mouth-piece situated in the main air supply passage having its discharge end located proximate to the point of reduced pressure and open at the opposite end for air inlet, a liquid fuel discharge duct extending horizontally for discharging into the air current entering through said fuel inlet mouthpiece; and at a considerable distance above the governed liquid level of the fuel supply chamber, a chamber substantially at the level of said fuel discharge, from which chamber said discharge duct leads to its discharge end; a duct leading upward from the fuel supply chamber located at the fuel discharge level and delivering at its upper end in said last mentioned chamber, and a duct leading from the top of said chamber to a point in the intake passage beyond the seating point of the throttle valve therein.

'2. In a carbureter,.in combination with a liquid fuel chamber, a main air supply passage open at one end for air inlet, and adapted for connection at the other end with the engine intake, said passage being constructed for causing reduction of pressure to re-. sult at a predetermined point therein from air current therethrough, a fuel inlet mouthpiece situated in the main air supply passage, having its discharge end located proximate to the point of reduced pressure in the main air intake, and open at the opposite end for air inlet; a liquid fuel discharge duct extending substantially horizontally for discharge into the air current entering through said fuel inlet mouth-piece; a throttle valve located in the main air supply passagebeyond the point of low pressure therein, a liquid fuel supply by-pass passageleading from the liquid supply chamber for discharge into the intake passage beyond the seating point of the throttle valve therein, said by-pass passage leading past the level of the horizontally-extending liquid fuel dis charge :duct and; being connected therewith,

sage beyond the throttle valve, whereby a supply 0f-liquiclfuel-drawn into said by.-

pass passage by. the suction vwhen the throtg tle Valve is Closed, is retarded in its return to the fuel. supply chamber, and is held 10 available at and above-the level of said horizontally-extending liquid fuel-discharge pas-- sage when suction :is operative through said passage. AH r 1 r In testimony whereof, I have hereunto set 15 my hand at Chicago, Illinois, this 21st dayof November, 1918. 1 I I \VILLIAM A. EDW'ARDS, I

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