US2520120A - Engine fuel system - Google Patents

Description

Aug. 29, 1950 A G, BODlNE 2,520,120

ENGINE FUEL SYSTEM Filed OCt. l2, 1946 Pressa/'e (Ittorneg Patented ug. 2K9,A 195() UNITED STATES 'PATENT OFFICE ENGINE FUEL SYSTEM Albert G. Bodine, Van Nuys, Calif,

Application October 12, 1946, Serial No. 702,982

7 Claims. l

This invention relates generally to engine fuel systems and more particularly to an extremely simple l flow control device for controlling the proportionality between fuel and air for internal .combustion engines. The invention includes a ,carburetor of the type employing venturicontrol Aof1 a flow regulator valve.

This application is a continuation-inf-part of my `copending parent application Ser, No. 299,830, ledOctober 17, 1939, now Patent No. 2,409,611, Gctober 22, 1946, and entitled Fuel for Internal Combustion Engines and Method and Apparatus for'Using Same. Discussion and claims'herein are directed to an especially simple form of my broadiinvention disclosed in said parent applicationwhich I have found by test to be applicable to-a large number of engines.

Many carlburetic-n proposals have been offered by' other inventors wherein the air-floW-respon- .sive proportional pressure differential created by an air-venturi is used to operate, in pressure dif,- lferential.relationship, a pressure controlled fuel metering valve. These attempts have beenextremely ambitious, attempting to accomplish a multitude of advantages. The net result of these prior efforts, however, has been a few successful carburetors of great complication suitable for specialized aircraft but unsuitable from the standpoint of first cost and maintenance difculties for automotive and other general use.

It must be admitted that, in specialized cases, there is certain advantage in having a carburetor and fuel system, such as. the multiple diaphragm types proposed elsewhere, insensitive to the pressure at which fuel is delivered to the metering system and insensitive to the orientation of the carburetor, such as for aerobatics. However, by choosing one form of my fuel system intended for engines that have a reglated pressure fuel source, and that stay right side up, it is :possible to make available to the public for the first time a very simple and conservative Venturitype carburetor having the one major advantage that permitsintroduction of the fuel stream (after metering) Ato the air streamat one -or more of anumber of Vdesirable locations, not necessarily at the venturi, and with'any'desiredapplication .of heating or pumping before said introduction.

Aniobject of my invention is to provide a car# Jouretor in which it is possi-ble to apply heatlandmr pressure to the fuel, after the now rate is metered, beioreintroduction t the air stream. Very good atomization and mixing can thus befaccomplished AWit-hout necessitating heating-the entire l'manifold and air stream, causing .consequent 'loss n-volumetric efiiciencyoi the' engine and reduced .antiknock Value `of thefuel-air mixture.

Another object .of myv invention is to provide a simple fuelsystem permittingfuel introduction, after metering, toany desired number of locations in. a multi-cylinder engine manifold having less than the corresponding number of air introduction openings.

'The invention will 'be fully 4understood from the following detailed description of a present illustrative embodiment thereof, reference for this purpose being had to the accompanying drawings, in which:

Figure 1 is a..crosssectional View .of a fuel-air metering mechanism in acordance with the invention.; and- Figure V2 shows the engine fuel system with a fuel chamber .ahead .of the metering unit.

In the drawings, numeral El? designates an induction pipeadapted .to supply the lfuel-air charge to .the intaliemanifoldoi an engine, this induction pipe @Si being- `provided with .a butterfly valve 5l, .a restriction, preerably a venturi .5.2 for creating .a pressurel differential proportional to air now, :and ,an air inlet t3 (suitably. the .open end ofv pipe Sil). The venturi visxsuppliedwith a lateral tap or jet iii.. ,An opening isvprovided in the induction pipe 6.0 downstream frornfthe 'butterfly valve, which opening iS snugly ntted a tubular fuel delivery member or conduit 65 `adapted at 'l0 to discharge within pipesl), This tubular member is provided-with a shoulder Bwhich abuts against the; interior wall ofthe pipe 610. The -member continuesiexteriorly `of the pipe @il with a thread- 4ed portions]l Which'is screwed into a re-entrant tubular member :63 integral with a shell or casing ,69 for certainfpresently described carburetor or fuel metering elements. The tubular mem'- .ber 65 is so arranged and dimensioned that it is adapted to receive the fuel discharge-d Afrom the carburetor and transmit" it to the combustion air stream.

The interior of the shell or casing 69 is divided intov two Vcompartments F andV G by a movable .ditterential pressure responsive element, here in vthe form of a diaphragm l5 having a compliance at lia and whose rim portion is clamped and sealed to thefcasing 69 `as indicated. The two sides of this diaphragm provide opposed pressure application areas to which differential pressures are applied as will presently appear.

Securely fixed to and movable with the central portion oi the diaphragm'l5 is a metering valve member 'I6 `whose conical-lower end portion coopcrates 4with a valve seat l'l to Vforma discharge valve. The valve seat T1 is securely mounted on the upper end portion of the re-entrant tubular member 68 by means of a threaded collar 18.

Air may, in some cases, be supplied to compartment G through an adjustable needle valve 80 primarily to prevent accumulation of atmospheric vapor condensation; the provision of such an air vent is sometimes necessary when passage 90 is not used to conduct a flow of fuel. A fluid fuel stream is supplied to compartment F through an adjustable needle valve 8| providing a metering orifice. If desired, the fuel stream supplied the adjustable needle valve 8| through the fuel supply conduit or tubing 82 may rst be passed in heat exchange relationship with the liquid or metal situated near the discharge valve as has been indicated in the drawings.

It is required that the intake air at 63 and fuel to valve 8| be delivered at substantially the same pressure or at least in some definite pressure relationship. The fuel is preferably a liquid, and can be either a high or a low vapor pressure liquid fuel. In some instances, the valve 80 may be closed entirely, as will later appear. The fuel chamber is indicated by the numeral 83, the lower end thereof being connected to the needle valve 8| by the tube 82 whereby the valve 8| may be supplied with the liquid fuel from said chamber. The upper end of the chamber 83 may be connected to valve 8|] by tubing 84, and, as shown, the top of chamber 83 will be vented to atmosphere as by means of vents 83a, or atmospheric venting can be accomplished by breaking tube 84, as shown. If a high vapor pressure fuel is to be utilized, the unbroken tubing 84 is useful as it prevents loss of fuel vapors. However, this provision is not essential, since even with high vapor pressure fuels, the line 84 can be broken, or valve 80 closed or omitted, without substantial penalty. In either event, air entering valve 8D, if open, will then be only air, and further, fuel line 82 will be at substantially atmospheric pressure. It will be evident that the system in this form (with or without the line 84 broken), or with the valve 80 closed or omitted, is suitable when low vapor pressure fuel, such as will not give off a substantial gaseous fraction, is to be utilized. In Figure 2 the induction pipe 60 is shown as connected to a manifold 85 feeding the cylinders of an internal combustion engine 88.

Differences in source pressure may also be taken care of by appropriate adjustment of the valve 8| provided that under conditions of no fuel now the discharge valve 16 will remain stable in closed position. It is frequently desirable to add a slight closing bias to the discharge valve as by means of a spring 83 adapted to exert a slight closing force on the diaphragm T5,

Air introduced through the needle valve 80 into compartment G is introduced into the induction pipe 60 at venturi 82 through the tap 64 which may act as a jet restriction. The air in compartment G is in communication with tap 64 by means of interconnecting tubing 90. A pressure regulator 9| and cut-olf valve 92 have been shown in fluid line S0, in accordance with the disclosure in my original Patent No. 2,409,611, but for present purposes, where the fluid introduced to the system through needle valve 80 is only air, at atmospheric pressure, or the needle valve 88 is closed (or omitted), these members may be dispensed with if desired.

If it is assumed that the air into 63 and fuel into 8| are at the same pressure, which pressure will be hereinafter referred to as storage pressure (being in the present case substantially atmospheric), then the pressure in compartment G will drop below storage pressure by an amount dependent upon the suction developed in line 90 by the action of venturi 62.

The valve 8| is constantly open an adjusted amount. However, in the absence of any substantial flow of fuel through the valve 8| and into compartment F, due to the closing of valve T6, 11, the pressure in compartment F would be substantially storage pressure. Under these conditions the pressure unbalance across the diaphragm 15 caused by pressure drop in G from air flow through 62 would cause the discharge nozzle to open, thus permitting flow of fuel through compartment F and into the induction pipe 60 via member 65. This flow of fuel results in a pressure drop across the needle valve 8| which reduces the pressure in compartment F so that the diaphragm 15 will eventually come to rest at an equilibrium setting of the discharge valve so that the pressure drops become equalized. The rate of flow of fuel is thus proportional to the pressure decrease in chamber G and both are effectively controlled by the rate of air travel through the venturi so that the desired relationship between total air induction and total fuel induction is thus had.

Valve 8|) may be closed down to any desired degree, or even closed entirely. In this closed example, the air in pipe becomes simply a displaceable pressure transmitting body still maintaining a proportionality between venturi air flow pressure and pressure in G, which proportionality is in this instance an exact equality. The net result in all cases of my invention is maintenance of the metering pressure in F proportional to the air-metering head produced by the venturi, and in the special case here given this proportionality becomes an equality as just mentioned. When valve 80 is closed the standard pressure regulator 9| automatically opens full wide in conventional manner, therefore becoming not harmful but unnecessary and easily substituted by a simple continuation of pipe 90. It is also obvious that tap 64 is the source of air for tubing 9D and compartment G when valve 8B is closed. Thus the source of air in pipe 98 is air at atmospheric pressure taken in at 63. Increasing the air flow through venturi 62 will cause extraction of air from G and back into the air stream at tap 64, as described above, giving consequent pressure drop in G, and therefore movement of diaphragm 'l5 to increase the flow of air through valve 16, 11. When valve 8D is closed the pressure decrease is the full suction created by the venturi, thus giving the simplest example of related function between pressure in G and venturi air flow.

The metering remains unchanged by any variations in the pressure in the induction piping into which the fuel is discharged. This point is particularly important since it permits the injection of the fuel into the manifold at a point downstream from the butterfly valve. The pressure at this point downstream is variable but is usually substantially less than atmospheric. This relatively low pressure or partial vacuum at the point of fuel discharge is of great value in improving the rapid vaporization and dispersion of the fuel throughout the air. The tendency toward icing is also thereby decreased since partial vacuum effects corresponding reduction in the vapor pressure of the water normally associated with the air and also because the point of injection which is permissively downstream from fixez-'butterflyvalve can be located; closer :to: the

where .the Vmanifold. walls are. warmer.

This .carburetor adapted to meter the fuel inthe liquid phase and under the pressure necessaryto insure the maintenance of .the fuel in the, liquid phase. Furthermore, no metering pumpsrarernecessary to thus meter the liquid, the metering being performed solely in response to the; venturi pressure. This carburetor may be aptly-.described as a Venturi-controlled, injector typescarburetor. Another important feature is that the effective metering is done by the discharge valve and at the point of dischargeso that .the metered liquid may be immediately 4completely free to escape into. ythe induction pipe. This is of particular advantage in using high vapor pressure fuels Where theattempt to first meter a given quantity of the liquid and subsequently toV discharge it through apressure reduction valve may give rise to very uneven discharge from such a pressure reduction valve due to partial Vaporization and/or changes in pressure and temperature between the metering device and the final discharge valve.

The tubular member 65 may be extended as a long; duct in heat exchange relationship with air'movng. through the pipe S0 so that the 4Viv-'Dori,Zatioil`v of the fuel in .the duct cools the air indirectly. The vaporized fuel may then be injected directly into the combustion cylinders beyond the intake manifold suitably by means of an injecting or distributing system, so that some further increase in volumetric efficiency may be obtained.

I prefer to use a portion of the latent heat of vaporization to cool the fuel charge in the carburetor and to prevent the premature gasification of any portion of the fuel such as might tend to rise from the liow of engine heat into the carburetor shell or from pressure reductions incident to the transfer of the fuel from the storage tank to the carburetor and the passage of the fuel through the pilot orifice. This is preferably accomplished by the use of a re-entrant discharge duct such as the tubular member 68. The refrigeration at and immediately below the discharge valve thus becomes available for cooling the contents of the carburetor. This refrigeration may also be very advantageously used to pre-cool the feed to the carburetor, as is indicated by the tubular means 82. If such precooling of the feed and/or refrigeration of the carburetor is not employed, it will usually be found necessary to employ a pump in the fuel transfer lines to build up the pressure to a value sufficient to prevent premature vaporization.

Many other advantages of my method of carburetion over the conventional carburetion will :be apparent to one skilled in the art. The severity of backfire is lessened in my device since I inject the main portion of the fuel downstream from the venturi and butterfly whereby the total volume of inflammable material can be made materially less than in the conventional practice of introducing all of the fuel at the venturi and/or upstream from the butterfly valve.

I claim;

l. An apparatus for continuously metering fuel and air to an internal combustion engine comprising: an air conduit for a combustion air stream having an air inlet and having an outlet adapted to be connected to said internal combustion engine, a restriction in said air conduit, a movable differential pressure responsive valve actuating; meansicomprising a .single wall having .only two; sides;y defining two opposed pressure appl-icationar-eas-,an air pressure communication between said` restriction and one only Aof said pressure; application. areas,.an .open continuousiowY fuel .supply conduit inpressure communicationV with only the `other .of said pressureapplication'. areas, saidxvalveY actuating means being subject to air pressure influence solely at said one .of said pressurexapplication areas, and being subject to fuel supply pressure influence solely at. said other of.v said pressure application areas and solelyf from the said `open continuous-flow fuelsupply` conduit, in such manner that decrease in' air pressure tends to move said valve actuatingfmeans in one direction, ,and decrease vin fuelsupply'pressure tends to move said valve actuatingmeans in the opposite direction, whereby said means moves under a differential of said pressures, afuel .delivery conduit in communication; with said fuel supply .conduit and varranged to'discharge to.saidi.co1rrbustion air stream, a metering valve controlling fluid flow -tzirough said fuel delivery conduit, said metering valve :being operably. .connected to saidjdifferential pressure responsive valve actuating means in such manner thatsaid metering valve tends to open with decreasein pressure .communicated from said-restriction to said first mentioned' pressure appli.- cation area and tends to close with decrease in continuous flow pressure communicated from said fuel supply conduit to the second mentioned pressure appiication area.

2. An apparatus for metering fuel and air to an internal combustion engine comprising: an air conduit for a combustion air stream having an air inlet and having an outlet connected to said internal combustion engine, a restriction in said air conduit, a casing, a movable differential pressure responsive diaphragm dividing said casing into two chambers, opposite sides of said diaphragm forming two opposed pressure application areas, a pressure communication between said restriction and one of said chambers, a fuel supply conduit in pressure communication with the other of said chambers,` a fuel delivery conduit in communication with said fuel supply conduit and arranged to discharge to the said combustion air stream, a metering valve controlling fluid flow through said fuel delivery conduit, said metering valve being operably connected to said differential pressure responsive diaphragm in such manner that said metering valve tends to open with decrease in pressure communicated from said restriction to the rst mentioned chamber and tends to close with the decrease in pressure communicated from said fuel supply conduit to the second mentioned chamber.

3. A combination as defined in claim 2, including means delivering fuel to said fuel supply conduit at a pressure substantially equal to the pressure at the inlet of said air conduit.

4. A combination as defined in claim 2, including a fuel chamber delivering fuel to said fuel supply conduit at a pressure substantially equal to the pressure at the inlet of said air conduit.

5. A combination as defined in claim 2, including an atmosphere vented fuel chamber delivering fuel to said fuel supply conduit at a pressure substantially equal to the pressure at the inlet of said air conduit.

6. An apparatus for metering fuel and air to an internal combustion engine comprising: an air conduit for a combustion air stream having an air inlet and having an outlet connected to said internal combustion engine, a restriction in said air conduit, a movable diierential pressure responsive element having two opposed pressure application areas, a pressure communication between said restriction and one of said areas, a fuel supply conduit in pressure communication with the other of said areas, a fuel delivery conduit in communication with said fuel supply conduit and arranged to discharge to said combustion air stream, said fuel supply and fuel delivery conduits being arranged in heat exchange relation with one another, a metering valve controlling fluid iiow through said fuel delivery conduit, said metering valve being operably connected to said differential pressure responsive element in such manner that said metering valve tends to open with decrease in pressure communicated from said restriction to said rst mentioned pressure application area and tends to close with decrease in pressure communicated from said fuel supply conduit to the second mentioned pressure application area.

'7. An apparatus for metering fuel and air to an internal combustion engine comprising: an air conduit for a combustion air stream having an air inlet and having an outlet connected to said internal combustion engine, a restriction in said air conduit, a movable differential pressure responsive element having two opposed pressure application areas, a pressure communication between said restriction and oneof said areas, an air vent for said one of said areas, a fuel supply conduit in pressure communication with the other of said areas, a. fuel delivery conduit in communication with said fuel supply conduit and arranged to discharge to said combustion air stream, a metering valve controlling iluid ilow through said fuel delivery conduit, said metering valve being operably connected to said differential pressure responsive element in such manner that said metering valve tends to open with decrease in pressure communicated from said restriction to said first mentioned pressure application area and tends to close with decrease in pressure communicated from said fuel supply conduit to the second mentioned pressure application area.

ALBERT G. BODINE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,861,352 Miquelon May 31, 1932 2,409,611 Bodine Oct. 22, 1948

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