US1814601A - Carburetor - Google Patents

Description

Juny M, w31. Q F, JOHNSON 1,814,601

l CARBURETOR Filed March 24 1923 Patented .Fully 141, 1931i Parent @este CHESTER 1E'. JOHNSON, 0F DETROIT, MICHIGAN mantenerme.,

' Application led March 24, 1923. Serial No. 627,468.

The invention relates to mechanism for controllingthe flow of fluids and, while in some respects of more generic application, is especially applicable to oarburetors of the type designed for supplying an explosive mixture to internal combustion engines.

One object of the invention is to provide improved means for varying the flow of a fluid or for varying the proportions of the.

1 constituents of a mixture of fluids, particularly in response to variations in temperature.

Another object is to provide improved carburetting means including temperature-responsive control devices operative upon a rich mixture of gas and liquid and, by varying the quantity thereof, effective to' vary the quality of a final mixture of which said rich mixture is a constituent.

A further object is to provide means in connection with a carburetor of the air bled nozzle type for varying the supply of alrich mixture of air and liquid to the mam mixing chamber u thereof in accordance with temperature 2 changes. f

A further object is to provide heat-respon-v sive means for ualifying the mixture supplied by a car uretor particularly .upon starting or at low or idling engine speed.

A further .obj ect is to provide, in connection with a carburetor, means operable manually from a distant point, as from the drivers station of a motor vehicle, rendering the engine suction -ineHective to draw liquid fuel from the fuelreservoir of the carburetor.

A further object is to provide, in combination with the ignition controlling means of" an engine, means operative to prevent supply of explosive mixture to the engine when the said controlling means is placed in the olf position. f' p rlhe above and other objects and advantages will appear more fully from the following description taken in connection with the accompany-ing drawings showing various features of the invention as applied, by way of illustrative embodiment, to a carburetor of well known type ada ted for use in a motor vehicle power plant. tion, however, and its specific description uch illustration of the-inven,

herein as applied to the formation from liquid fuel and air of an explosive mixture for use in the internal combustion engine of a motor vehicle is not intended as in any way a limitation to such' use except as required vby the language of the appended claims since it will be understood that the invention in its broader aspects may be applied to controlling the quality or proportions of a mixture of uids whether liquid or gaseous and for use as fuel or otherwise.

In the drawings, Fig. 1 is a central vertical section through a carburetor showing features of the invention;

Figs. 2 and 3 are similar yviews of a portion of acarburetor illustrating dierent locations of thermostatic control devices;

Fig. 4 is a similar view showing a modified form of carburetor in which the -invention may be embodied;

Fig. 5 is a diagrammatic view, partly in section, showing another embodiment of one feature of the invention;

Fig. 6 is an elevation showing the application of the invention to a motor vehicle power plant; and

Fig. 7 is an enlarged view, partly in section, showing a detail of a controlling device used with the invention. f

Referring to the drawings, Fig. 1 showsia carburetor having a body portion or casing 10 enclosing a mixing chamber. The body portion is provided with an extension 11 adapted to be connected to the intake manifold 12 of an engine 13 (Fig. 6), and within which may be mounted the throttle valve 14. Any usual or desired form of air valve indicated at lmay be provided to admit auxiliary air tol the mixing chamber in response, preferably, to sub-atmospheric conditions therein. A spring 16 may be utilized to control the opening of the valve 15.

In the bottom of the casing `is a strangle tube 17 into the lower end of which the nozzle 18 projects. A fuel reservoir is provided comprising a cover or diaphragm 19 and a bowl 20, liquid fuel in which may be maintained at the desired approximately constant level by any usual or suitable control means,

asy by a float valve 21. The nozzle may be y formed, as lshown, integral `with the diaphragm or cover 19 and air supply apertures 22 are provided to admit air to the lower end of the strangle tube whence it may flow upwardly past the nozzle into the main mixing chamber or supply passage of the carburetor.

Ak fuel passage 23 connects the interior of the reservoir or lioat bowl 20 to the nozzle, the passage being formed preferably with a constriction as at 23. Opening into this passage in the upper portion 24 thereof above the constriction 23 and preferably above the normal level K.of the liquid in the reservoir is an air vent passage 25 adapted to admit air linto the fuel column flowing through the chamber or mixing tube y24 under the influence of sub-atmospheric conditions in the main mix,- ing chamber or, in general, of pressure differences between the source offuel and the passages leading to the mixture utilizing devices. The use of an air passage leading to the liquid supply passage anterior to the nozzle but above the normal level of liquid as a means for desirably varying the quality of the mixture within certain ranges of the effective suction, as, for example, in accordance -with variations in speed of an engine to which the mixture maybe supplied, is well known in the carburetor art. In such devices the flow of liquid toward the nozzle is accompanied, of course, -by a iiow of air through the air pas'- sage', the relative proportions varying slightl with variations in suction, and hence the fliel issues from the nozzle in the form of an aerated column or a partially atomized but normally very rich mixture of fuel with air.

In accordance with the present invention l further modify the quality of the mixture by means responsivel to temperature changes.

This means may take various forms but is shown in Fig. 1 as comprising a valve-like member or obturating device 3Q arranged to obstruct to a greater or less extent the flow of the air-liquid mixture from the mixing tube or nozzle 18. The devicen is carried upon the free end of, or otherwise arrangedto -be, moved by, a thermostatic element, as 31, which, in theform illustrated, may be a bimetallic bar or blade of a well known type. The blade may be secured at the xed end bv a screw 32 and initially adjusted by `an additional screw 33. The thermostatic element is designed to be so mounted that lowering of 7 the environment temperature will result in increased iiow through the mixture forming assage 24, whereby a richer mixture will be ormed in the main mixing chamber. By this means the necessity for seasonal adjustments of the carburetor is eliminated as the heatresponsive control device ma be so designed as to compensate automatica ly for seasonal or other changes 1n environment temperature',

enriching the mixture to the desired extent for operation in the cold and rendering the mixture leaner for economical'and satisfactory operation as the temperature rises. will be noted thatthe thermostatic device is so positioned as to be affected by the entering mixture of external air and fuel, and is therefore adapted to vary the flow in accordance with the temperature of the mixture itself. Additional means may be provided to vary at will the relative proportions of the constituents of the mixture by adjustment of the capacity of the air passage 25. This is effected preferably by extending the air conduit 35, leading to the air passage 25 to a point convenient for access by the operator, as to the dash or instrument board 36 of a motor vehicle. At this point' I\ provide the atmospheric inlet 37 controlled by the valve or screw 38. By adjustment of the screw the operator may vary the initial effect of the air bleed oriiice and the resulting quality of the mixture through all ranges of speed.

In addition to the manually adjustable control devices just described I provide an orifice 40 in the conduit which may be covered at times by the closure 41. The capacity of this orice is such that, when it is opened, free llow of air is permitted through the conduit and passage 35 to such an extent as to reduce the vsuction in the fuell passage below that required to lift fuel from the float bowl. The-y iow of fuel is therefore suspended so long ignition mechanism of the engine. As a re-v sult of this arrangementthe feeding of fuel from the carburetor ,is automatically suspended when the ignition circuit is broken. This effects material economy in use of fuel particularly in hilly sections where it is customary, and is in fact recommended by authorities, to throw the ignition switch to off position when .using the engine for braking while descending h1 ls.

With the usual arrangement of carburetting apparatusthe interruption of lignition when the engine is being used as a brake res'ults inthe pumping of explosive mixture through the engine and wastes a considerable amount of fuel besides being followed frequently by annoying and sometimes damaging explosions in the exhaust system when the ignition current is again turned on. These ldificulties are entirely eliminated by the present invention.

Inl the embodiment of the invention illusF trated in Fig. 2 a chamber 45 is formed in the fuel ,`supply passage 46 leading to the` primary`ffmixing tube 24 in the nozzle 18 i f Lsiaeoi rating device 47 adapted to restrict the flow of commingled air and fuel through the `dis.

charge orifice. The device 47 is carried by the thermostatic blade 48 which may be supported upon the block 49 held in position by` a screw 50. ln this form the thermostat is iniuenced chiefly, when the mixture is being deliveredg'by the temperature of air or other gas flowing through the conduit 35 into chamber 45. The air or other mixture constituent supplied through the conduit 35 may be derived from any' suitable source depending upon the application of the invention. The chamber 45 and delivery passage therefrom operate as a mixing chamber for forming, when the constituents comprise air and liquid fuel, a very rich mixture which is delivered to the main mixing chamber within the casing 10 through the secondary mixing tube 17. The thermostat is arranged, as in the form first described, to cause a reduction in the flow of rich or primary mixture as the temperature rises.

In the form shown in Fig. 3, the obturat- Iing device 8O is positioned in the mixing tube 81 and is carried by the thermostatic element 82 fixedly secured as by screw 83 and adjustable as by screw 84. A mixture, which may e a rich or primary mixture if it is desired to add a further constituent or diluent beyond the tube 81, is formed within the tube 81 or may be supplied thereto, as from a mixing passage 85 to which fuel flows past needle valve 86 and air through passage 87. The tube 81, which may correspond to the strangle tube 17 .of the forms elsewhere shown, is tapered, and the movement of the obturating device 8O operates to obstruct to a greater or less extent the flow of mixture from the mixing tube as the temperature varies. This device may be, hemispherical form to maintain the width of' the passage between it and the tube as nearly uniform as possible on all sides in any given position of adjustmentnotwithstalrding the tilting that occurs as the device moves upwardly or downwardly.

For co-ntrolling the flow of explosive mixture to an engine the thermostatic actuating means will be arranged, of course, as in the forms previously described, to reduce the flow as the tempera'.- ture rises.

While inall of the applications of thermostatic contro-l devices above described the fluid whose flow is controlled is a iuid mixture resulting from the comlningling of a gas and a liquid itwill be understood that the invention is not limited to such use, Either or both fluids may be gaseous or liquid or a single homogeneous iuid may be controlled and the flow past the obturating device may be the result of pressure differences aecting one or a plurality of conduits. When one constituent of a mixture, for example, a fuel, is of substantially uniform temperature and the other, for example, air, is subject to variation, as from atmospheric conditions or from the heating effect due to combustion of the linal mixture, then the thermostat will aEected chiefly by the variable constituent and may operate to control flow in accordance with heating eects directly responsive to or proportionately affected by the fluid whose flow is controlled.

Where the invention is applied, as in a carburetor, to the control of flow of a rich or primary mixture, it affords a means for attaining a more accurate control of the quali-' ty of a final mixture than would be possible by varying the flow of liquid, inasmuch as the quantity of material passing through the controlled orifice is much greater than if it were liquid fuel only, hence a much greater range of movement of the obturating device is available and slight variations in viscosity or other properties, or irregularities in (manufacture and adjustment, exert much less disturbing eifect.

In the carburetor ishown `in Fig. 4, two fuel supply devices are provided. @ne of these, illustrated as a common form of jet nozzle 55 to which fuel may be supplied in any. usual or desired manner as from the bowl 20 through fuel passage 56 controlled by needle valve 57, serves to supply fuel to the mixing tube 17 within casing 10. Flow of fuel through this device however, is very much reduced when the throttle valve 14 is closed or nearly closed, since at that time suction tending to 'cause flow from the fuel reservoir is relatively low. A second device is provided to supply fuel when the throttle is at or near its closed, position. This device may comprise a tube 58 fixed in the base of casing end below the normal level of fuel in reservoir 20. The upper` end of the tube communicates with a passage 59 in casing 1() to which passage air may be supplied by orifice 60. A mixture tube 61, slidably mounted in the upper end of passage 59 and in a guide lug 62, extends to a point near the throttle 14. The latter is provided with an aperture 62 immediately above the open upper end of tube 61 when the throttle is closed.l Under low speed or closed throttle conditions the greatly reduced pressure above the valve induces flow of fuel through'tube 58 to passage 59 Where the fuel mingles with air entering through the air bleeding orifice 60 and the resulting mixture is suppliedV to the passages above the throttle through the aperture 10 and having its open or perforated lower as shown, of approximately forms previously described. One form of suchmeans may comprise a bimetallic therv mostat blade 64 supported at one end, as by I flow of fuelmixture.

pivotal connection to casing 10 at 65, and restlngat the opposite end upon a collar 66 xed.

to tube 61. A spring 67 arranged under compression between the base of casing 10 and the lower side of collar 66 tends to force the tube upwardly to bring its discharge end into proximity to the aperture 62. A screw 68 engaging the thermostat. intermediate its ends provides an adjustable abutment whereby the thermostat serves to hold the spring 1n compression and determines the extent ofL upward movement of the tube 61. The thermostat is so positioned that its bending movement under the influence of indreased temperature carries the tube downward thereby increasing its distance from aperture 62 and correspondingly reducing the suction effect upon the supply passages and the resultant lt will be seen therefore that the supply of rich primary mixture for starting or idling conditions is varied in response to 'temperature changes, ay greater quantity and a proportionately richer nal mixture beingprovided when the environment temperature is low.

\ .When, in a carburetor, thethermostatic element is equally free to move in both directions from its normal or average position, the adjustment being such as to give a proper mixture for average temperature conditions and its range of movement under reduced temperature being such as to desirably enrich the mixture for cold weather, I have found that the movement in the direction resulting in reduced flow may be too rapid and the'mixture leaning effect too pronounced. To obviate this dificulty I may provid-e means to reduce the rate of movement in response to increase of temperature above the average or normal point. Une form of such means is shown in Fig. 2 where an abutment 90 is provided on the block 49 inposition to contact with the blade 418 after the latter has moved to a predetermined extent in the flow-reducing direction. -By this means the effective lengthof the blade is reduced and its further deflection in response to continued increments of temperature' increase'is.

correspondingly lessened.

ln Fig. 5 is shown/ a modied form of device forplacing the flow of fuel from the fuel reservoirof a motor vehicle carburetor under the control of the operator. In -this form meansis provided for forcing the auxiliary air valve 15 to a more open position against the iniuence of its spring 16, thereby reducing suction in the mixing chamber of the carburetor to such an extent as to interrupt the flow of fuel from the fuel reservoin In the embodiment illustrated this means comprises a `flexible connection, as a Bowden wire 70, one end of which is so positioned ,in proximity tol the air valve as to permit,

the vlever 71 is associated with the ignition v control means 72 as in the forms shown in Figs. 6 and l7 so that the throwing of the ignition switch lever to off position will automatically eect the openingof the air valve. While, in this form of the invention, the auxiliary air valve is utilized to effect control of flow of Ifuel it will be understood that other 4means capable of interrupting the fuel How may be similarly utilized. Various other modifications and variations/ in details of construction and in the appli-v cation of the invention maybe made, of course, without departing from the spirit and scope of the invention and therefore li do not wish to be restricted by the illustrative embodiment herein set forth except as required by the language of the appendedv claims in view of the prior' art. lf claim:

1. A carburetor comprising a receptacle forF liquid fuel adapted to maintain fuel therein at substantially a c'onstant level, a mixing chamber, a passage through which fuel is discharged from said receptacle into said :mixing chamber under the influence of suction in the chamber, and means for reducing the suction applied to said fuel including a passagej for supplying air to said fuel passage above the normal level of liquid in said receptacle and thermostatic means including a thermostat positioned in said air passage for controlling the discharge into the vchamber of the air and fuel supplied to said fuel passage.

2. A carburetor comprising av mixing chamber, a fuel receptacle, a fuel passage for supplying fuel from said receptacle to said chamber, means for supplying air to said chamber, the discharge orifice of said passage positioned to be subject to suction existing in said chamber whereby such suction operates to withdraw fuel from said passage, means for supplying air to said passage anterior to said oriiice to reduce thereby the suction exerted on the fuel and thermosta-tic means positioned in the path of flow of said fuel and air for controlling discharge from said orifice.

3. Strlfcture as set forth in claim 2 including meansfor varying the flow of air through said last-named air supplying means,

rsigeofi Il. A carburetor comprising a mixing plied to said first named passage, a thermochamber and means for supplying air there- Stat in Said air supply passage and a valve to, a fuel reservoir, a fuel passage leading atllated thereby and; arranged t COIIIOl from the reservoir and discharging into said dlSChIg@ t0 Sild Stmng@ tube.- n chamber, an air passage supplying air to said Ll testlmony whereof I am my Slgnatu'e- 70 fuel passage anterior to its point of discharge, HESTER .E JHNSN- a thermostat Comprising a bimetallic blade located in said air passage, and a valve controlled by said thermostat androntrolling flow to said mixing chamber.

5. A carburetor comprising a fuel reservoir, a mixing chamber, a passage arranged to supply fuel from said reservoir to said mixing chamber, a passage for supplying air to said first named passage, a thermostat in saidA air passage, and a valve controlled by said thermostat and operative to control How of fuel to said mixing chamber.

6. Structure as set forth in claim 5, including means for varying the rate of movement of said thermostat' over a portion of its range. 7. carburetor comprising a fuel reser# voir, a mixing chamber, means for supplying fuel and air to said mixing chamber comprising a nozzle, thermostatic means located in the air passage leading to the nozzle for .controlling the relative proportions of fuel and air, and means for reducing, as the temperature rises, the rat'e of movement of said thermostatic means over a portion only of its range of movement in a direction to reduce the relative quantity of fuel.

8. A carburetor comprising a mixing chamber, a. strangle tube leading thereto, means for supplying primary air to the inlet K end of said tube andauxiliary air beyond the tube` a fuel reservoir, a passage for supplying fuel from said reservoir to said strangle tube, an air passage communicating with said fuel passage between said reservoir and said tube and slightly above the level of fuel in said reservoir and a thermostatic valve ar-y ranged to control flow to said strangle tuben 9. A carburetor comprising a mixing chamber having an auxiliary air valve and a strangle tube lleading thereto, a doatbowl below said chamber, a cover for said bowl having therein a fuel passage leading from said bowl to said tube and an air passage communicating with said fuel passage, and a thermostatic valve arranged to control ow to said tube. g

10. Structure as set forth in claim 9,"the thermostat controlling said valve being posi- 12@ tioned in said air passage.

ll. A carburetor comprising a fuel reservoir, a main mixing chamber, means for supplying auxiliary air thereto, a strangle tube so leading to said chamber, means for supplying 125 air and a rich fuel mixture to said tube, said vfuel mixture supplying means comprising a passage leading from said?` fuel reservoir and subject to the suction in said strangle A tube and a passage through which air is supi130

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