US 2409611 A
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Oct. 22, 1946. G BODINE 2,409,611
CHARGE FORMING METHOD AND APPARATUS FOR INTERNAL-COMBUSTION ENGINES- Filed Oct. 17, 1939 3 Sheets-Sheet 1 Fi .1. a
HARRIS, mac, F 0: r0? 3 HAP/PAS F P 7W5 FIRM A rrgmvz s.
Oct. .22, 1946. G; B DlNE 2,409,611
CHARGE FORMING METHOD AND APPARATUS FOR INTERNAL-COMBUSTION ENGINES Filed Oct. 17, 19:9 2 Sheets-Sheet 2 JNVENTOR BY ALBERTG. Boo/Ms HARRIS, Kmch; Fos r51? & H4225 FOR mil-TQM 2 1946 A..G. BODINE 2,409, 11 CHARGE FORMING METHOD AND APPARATUS FOR INTERNAL-COMBUSTION ENGINES Filed Oct. 17. 1939 5.Sheets-Shet 5 figs f/wE/v T01? ALBERT 6. BUD/NE Patented Oct. 22, 1946 TUS GIN ES FOR INTERNAL-COMBUSTION EN- Albert G. Bodine, Los Angeles, Calif.
Application October 1'7, 1939, Serial No. 299,830
17 Claims. 1 This invention relates to fuels and fuel systems and relates more particularly to high vapor pres sure fuels and to apparatus adapted to supply such fuels to internal combustion engines, including carburetors and storage tanks.
Fuels for internal combustion engines are conventionally of the Diesel type, gasoline type, or gaseous type. This invention is concerned with the composition of and methods for handling a still further type of fuel which in some respects is intermediate in characteristics between gasoline and gaseous fuels.
As a general rule, gaseous fuels such as methane, ethane, propane and butane possess many advantages over the gasoline type of fuel, for example, an inherently very much higher knock rating, cleaner operation, and less tendency to form carbon deposits, avoidance of fuel condensation in the manifold and combustion chamber, absence of crankcase dilution, and the like.
These advantages inherent in the gaseous fuels have hitherto, however, been oifset by decreased mobility and simplicity of equipment, increased bulk and weight of storage containers for the fuel, and the like. Gasoline has hitherto represented the most volatile fuel that could be conveniently handled, stored in storage vessels of reasonable weight, and accurately metered in the liquid phase in carburetors at atmospheric pressures. H In connection with the use of gaseous fuels, stationary engines which are located near a source of natural gas may use this gas without much difiiculty, but with engines remote from suitable sources, and more particularly with mobile engines for use in automobiles, trucks, aircraft, and the like, it is necessary that the gaseous fuel be transported. For such purposes propane or butane is usually used, being liquefied by the imposition of suificient pressure and being stored in the liquid condition in heavy metal containers or cylinders of adequate strength to safely resist the pressures involved. In use the liquid material is drawn from such a container as needed, heated above its flash distillation temperature to convert it into a vapor, passed through a pressure reduction valve to obtain the gas at suitable pressure, and then admixed with combustion air in a suitable carburetor. 1
Such equipment is very bulky and weighty and is difficult to handle and keep in adjustment. The natural vapor pressure of liquefied propane or butane imposes requirements for strength and Weight on the storage system that mitigate against the use of such systems in anythingbut very heavy duty equipment such as trucks. It is difficult to keep the carburetor in proper adjustment for a variety of reasons, including the fact that the proper metering of the gasified fuel depends not only on the pressure, but on other factors suchas the temperature which influences the density of the gasified fuel. Furthermore, the use of a completely gasified fuel for carburetion involves a certain loss in volumetric efiiciency, as contrasted with a liquid fuel.
It is an object of the present invention to provide a fuel having a substantially higher vapor pressure than gasoline and which approaches or equals pure propane or butane as regards the inherent advantages of such normally gaseous fuels, having particular reference to such advantages as high knock rating, enhanced ignition range, clean operation, lack of carbon deposits, absence of condensation in manifolds and crankcases, and light density. This fuel is so composed (suitably by the addition of a small amount of modifying agent to a propane or butane base, or by the addition of any normally gaseous fuel to a normally liquid and substantially less-volatile fuel) that the vapor pressure of the resultant product is substantially less than that of liquid propone or butane, whereby very much lighter storage vessels may be used and the incidental equipment lightened and simplified.
It is also an object of the present invention to provide carburetors in which high vapor pressure fuels such as the above and others may be metered under pressure and in the liquid phase, and injected directly as a liquid into the intake manifold or combustion cylinder.
It is also an object of the present invention to provide improved storage vessels for high vapor pressure fuels of the above type and other types, including storage vessels in which provision is made for automatic internal refrigeration to minimize the storage pressure.
Various other objects and aspects of my inven tion Willbecome apparent in the following dis- 3 vessel and fuel system adapted to automatically maintain the contents of the storage tank below any desired pressure by automatic internal refrigeration.
Fig. 5 is a cross-sectional view of another storage tank and fuel system providing automatic internal refrigeration in response to the development of excessive pressure.
Fig. 6 is a diagrammatic view showing the carburetor of Fig. 2 in its relationship with a fuel storage tank.
Fig. '7 is an alternative embodiment of the carburetor shown in Fig. 1.
Fig. 8 is an alternative embodiment of the carburetor shown in Fig. 2.
Referring more particularly to Fig. 1, i is an induction pipe for supplying air and fuel to the intake manifold of an internal combustion engine. The induction pipe E6 is provided with a venturi I I, a butterfly throttle valve l2, and an open end in communication with the atmosphere to supply an air inlet l3. Between the butterfly valve [2 and the intake manifold of the engine, pipe I!) is provided with a threaded opening l4 into which is screwed a threaded member 15 which is integral with a carburetor casing !B. The interior of the carburetor casing is divided into compartments A, B, C, D, and E by means of diaphragms ll, 18, i9, and 26 respectively. These diaphragms are all securely fixed to' and movable with a valve stem 25. The outer peripheries of all of the diaphragms are hermetically sealed to the carburetor casing H or abutments therefrom by means of flexible members Ila, iBa, 19a, and Zlla respectively. By means of these flexible members the valve stem 2| and the entire assemblage of diaphragms are free to move as a unit for a certain limited vertical distance within the casing it while maintaining the respective compartments sealed from one another.
The lower portion of valve stem 2! terminates in a conical valve member 22. A valve seat 23 suitably constructed as a circular washer composed of a resilient hydrocarbon resistant material such as neoprene or other synthetic rubber is supported on a re-entrant tubular member 24 which may be integral with the casing I6 and which provides a passageway 25 to permit the flow of fuel (metered by the discharge valve constituted by the valve members 2'2 and 23) into the induction pipe iii. The valve seat 23 may be secured in position on the tubular member 24 by means of a threaded collar 26.
Compartment A is in communication with a fuel chamber 39 suitably constructed as a small chamber in the carburetor casing l6. A constriated orifice or pilot jet 3! is placed between compartment A and the chamber 30 to limit the communication therebetween to a predetermined value.
Compartment B is also in communication with the chamber 30 by means of a passageway 32 which affords little or no restriction to free communication. A nipple 33 connects the chamber 30 to a T-member 34, one branch of which is connected to a suitable source of fuel supply (not shown), and the other branch of which is in open communication by means of tubing 35 with the upper compartment E.
Compartment D communicates by means of tubing ill with the venturi l I so that the suction of the venturi, which is proportional to the mass travel of air therethrough, is transmitted to compartment D. a
Compartment C is tapped by one leg of a hollow T 45, the second leg of which is closed by a plug 46 having a small hole therethrough to serve as an air bleed. The third leg of the T d5 communicates by means of tubing 41 with the pipe [0 at a point downstream from the venturi. Ihis communication is preferably effected through an impact scoop 48 having an open end facing upstream so that the pressure received and transmitted by the member 48 and tubing ll to compartment C represents not only the static pressure in the induction pipe H], but also the dynamic pressure due to the mass velocity of the fuel-air mixture flowing through the pipe I9. If desired, however, compartment C may be allowed to communicate directly with the atmosphere as by the removal of the plug 46, in which instance tubing 4'! may be suitably blanked off, and the butterfly I2 moved to a zone between the venturi H and the orifice 25, all as shown in Fig. 7.
The operation of this device is as follows. A suitable liquid fuel is supplied to the carburetor under pressure. Such a fuel is preferably a liquefied high vapor pressure fuel such as is described elsewhere in the specification, although this is not essential for the functioning of the carburetor and it may operate, for example, on gasoline delivered at a suitable pressure by means of a pump, or it may also operate on very high vapor pressure fuel such as pure liquefied pro ane. Due to the free communication between the T- member 34 and compartments E and B, the latter via the chamber 3|], these two chambers are at full fuel pressure. Compartment A is delivering fuel to the induction pipe l0 through the valve means 22 and the attendant flow of liquid fuel from the chamber 39 to compartment A past the pilot orifice 3| causes a pressure drop across this orifice so that the pressure in compartment A is less than that in compartment B by an amount which is proportional to the rate of fuel flow through the pilot orifice 3!. This unbalance of pressure across the diaphragm ll tends to move the diaphragm and valve stem 2i downwardly, or, in other words, tends to close the valve means 22. This tendency to close the discharge valve is offset by balanced forces in the opposite direction, as will presently be made clear.
The butterfly valve l2 being open at least par tially, the intake air flows through the venturi i l thus creating a suction which is transmitted to compartment D. For the moment it may be assumed that compartment C is freely open to the air and hence at atmospheric pressure. The pressure in compartment D is hence less than that in compartment C by an amount which is proportional to the Venturi suction. This. produces an unbalance of pressure across the diaphragm [9 which tends to move it upwardly and to open the discharge valve.
The discharge valve is thus subject to two opposing forcesone which tends to open it and which is proportional to the rate of air flow through the venturi, and the other which tends to close it and which is proportional to the rate of fuel flow into the induction pipe IE3. If the closing force is the greater, the entire valve stem and diaphragm assemblage moves downwardly, thus tending to close the discharge valve as defined by the valve elements 22 and 23. This has the immediate effect, however, of decreasing the rate of fuel flow through the discharge valve and hence the rate of fuel flow through the restricted orifice or pilot jet 3|. The pressure drop across this orifice 3| is immediately decreased and hence the unbalance in pressure between compartments A and'B is decreased and, in fact, brought to a point such that the closing force becomes equal to the opening force. The discharge valve then remains stable at this setting provided no other factors are changed. If the opening forces are at any time greater than the closing forces, it may be similarly shown that the discharge valve will be opened to a new equilibrium setting in which the opening and closing forces are balanced.
At this balanced setting of the discharge valve the closing force, which is proportional to the rate of fuel flow, is equal to the Opening force, which is proportional to the rate of air flow, and thus proportionality is at all times established between the rates of fuel flow and the rates of air flow so that a proper mixture of air and fuel may be had under all conditions.
In the final analysis, the entire system is responsive to the setting of the butterfly or throttle valve since this determines the rate of air flow through the venturi, which in turn determines The proportionality constant between fuel rates and air rates which determines the composition of the combustion mixture is best adjusted by variations in the size of the restricted pilot orifice 3|. If desired, this restricted orifice may be constructed as a manually adjustable needle valve so that the proper setting for mixture may be readily obtained.
Further factors are involved in the operation of the carburetor which are concerned principally with the balance of the minor forces set up across the diaphragms l8 and 2B and With suitable provision for idling. The unbalance across the diaphragm l8, which is proportional to the difference between fuel pressure and atmospheric pressure, is slightly more than counteracted by the unbalance across the diaphragm 20, which is proportional to the difference between fuel pressure and Venturi pressure. The forces involved here are relatively small, however, in view of the relatively small surface areas of these diaphragms, and a slight'bias in one direction or another does not introduce any substantial deviation in the desired proportionality between air and fuel flow. In some instances it is desirable to provide a slight closing bias to insure the secure closure of the discharge valve when the engine is not in operation, and this may be readily done, for example, by inserting a light spring 49 between diaphragm l9 and the top portion of the carburetor shell It.
In the above description of operation it was assumed that compartment C was open directly to the atmosphere and under these conditions the question of idling Was not discussed nor would suitable idling conditions be directly available. Many engines, however, notably airplane engines, are never run under idling conditions, but, if desired, conventional idling means may be employed.
The best method for control of idling conditions, however, is afforded by use of the means denoted by the numerals 45, 46, 41, and 48, and this means is furthermore effective in enrichening the mixture in full throttle operation, such enrichening being frequently very advantageous.
The operation of the above indicated means is as follows. When the butterfly valve i2 is closed or in idling position, a very low absolute pressure prevails in the induction pipe Hi. This low static pressure is transmitted virtually unchanged through the-tubing M! to compartment.
the rate of fuel injection into the induction pipe 6 D, the venturi effect under these conditions being very small due to the negligible flow of air. Compartment C is also in communication with the pipe in by means of the tubing 41 and scoop 4B but due to the small air bleed in the plug 46, which permits a small stream of air to enter the tubing 41 under the high pressure differential that exists under these conditions, the effective pressure in compartment C is somewhat higher than in compartment D. .As a result, there is a small opening force on the diaphragm l9 which keeps the discharge valve slightly open so that an amount of fuel suitable for idling is discharged into the induction pipe In. As before, the flow of fuel sets up a resultant small closing force across the diaphragm ll which balances the opening force and keeps the discharge valve stabilized at a suitable idling opening. A suitable idling mixture may be obtained by appropriate adjustment of the air bleed in the plug 46.
This device also serves to gradually enrich the mixture as the butterfly valve 12 is opened. For example, when the butterfly valve I2 is fully opened, the static pressure in the induction pipe to is approproximately atmospheric and this atmospheric pressure is transmitted by means of the scoop A8 and tubing 41 to compartment C. An additional dynamic pressure is also transmitted to compartment C, this dynamic pressure having its source in the impact of the rapidly moving charge in the pipe if! on the upstream opening in the scoop 48. This additional dynamic pressure in compartment C creates an additional force tending to open the discharge valve, thus resulting in a richer mixture. The degree of this enrichment due to dynamic pressure is proportional to the setting of the butterfly valve I2, which determines the mass velocity of the flow through the induction pipe IE3 and is hence greatest under full throttle operation in which the enrichened mixture is especially desirable for purposes of increased acceleration and power.
Referring more particularly to Fig. 2, is an induction pipe adapted to supply the fuel-air charge to the intake manifold of an engine, this induction pipe ti! being provided with a butterfly valve 6!, a venturi 62, and an air inlet 63 (suitably the open end of pipe 60). The venturi is supplied with a lateral tap or jet 64. An opening is provided in the induction pipe 60 downstream from the butterfly valve, in which opening is snugly fitted an L-shaped tubular member provided with a shoulder 65 which abuts against the interior wall of the pipe 60. The member 65 continues exterior of the pipe iii) with a threaded portion 61 which is screwed into a re-entrant tubular member 63 integral with a carburetor casing 69. The tubular L-shaped member 65 is so arranged and dimensioned that it is adapted to receive the fuel discharged from the carburetor casing and transmit it to the open end 153 which faces downstream and is positioned approximately coaxially with the pipe 69.
The interior of the carburetor casing 89 is divided into two compartments F and G by a diaphragm 15 sealed to the casing 69 by means of a flexible member 15a.
The diaphragm 15 is securely fixed to a valve member 16 which is thereby constrained to move with the diaphragm. The lower portion of the valve member 16 terminates in a conical member which cooperates with a valve seat I! to form a discharge valve. The Valve seat Ti is securely mounted on the upper end portion of the re- '7 entrant tubular member threaded collar 18.
A primary fuel is supplied to compartment G through a jet or restricted orifice shown as an adjustable but always open needle valve 80. A secondary fuel is supplied to compartment F by means of a jet or restricted orifice shown as an adjustable but always open needle valve 8!. If desired, the secondary fuel supplied the adjustable needle valve 8| may first be passed in heat exchange relationship with the liquid or metal situated near the discharge valve as by means of a tubing 82.
It is required that the primary and secondary fuels he delivered to the needle valves 80 and 8! at substantially the same pressure or at least in some definite pressure relationship. The secondary fuel is preferably a liquid, suitably a high vapor pressure liquid fuel such as is disclosed elsewhere in this specification. The primary fuel may be either a liquid or a as. For example, both the primary fuel and the secondary fuel may be constituted by the same liquid, for example, butane, which may be fed from a common line into needle valves 89 and 8! respectively. The primary fuel may very advantageously be a gaseous fraction derived from the high vapor pressure fuel. For example, the needle valve 86 may be supplied from the gaseous phase in a fuel storage tank, and the valve 81 may be supplied from the liquid phase in the same tank. Suitable storage tank connections for such usage are indicated in Fig. 3 and Fig. 6 discloses the complete combination, the storage tank being here indicated by the numeral 83, the upper end thereof being connected to the needle valve 80 by tubing 84 and the lower end being connected to the needle valve 8i by the tubing 82. Here, the induction pipe 68 is shown as connected to a mani- 68 by means of a fold 85 feeding the cylinders of an internal combustion engine 86.
If the primary fuel and the secondar fuel are delivered from storage under substantially different pressures or if the pressure relationship therebetween is highly variable, a conventional pressure equalizing means may be used to bring the fuels to the same pressure or to a definite pressure ratio before introducing them into the needle valves 80 and BI.
The primary fuel introduced through the needle valve 89 into compartment G is introduced into the induction pipe 68 at venturi 62 by means of the tap 64 acting as a jet. The primary fuel is conducted from compartment G to tap 64 by means of a tubing 90 and various auxiliary means the character of which will depend on the character of the primary fuel. Suitable auxiliary means for use in connection with a gaseous primary fuel have been illustrated and include a conventional gas pressure regulator 9| and a cutoff valve 52. The gas regulator 9! reduces the pressure of the gaseous fuel to approximately at mospheric pressure before permitting it to be aspirated into the venturi. The cut-off valve 92 is closed when the engine is not in use to prevent any leakage of primary fuel.
If the primary fuel is constituted by a liquid, the pressure regulator 9| ma be replaced by a liquid regulator (suitably a float chamber) which will supply the liquid at a constant head, all as shown in Fig. 8. Alternatively, a vaporizing unit Sla may be placed ahead of the regulator 9! and the liquid primary fuel converted to gas before submitting it to pressure regulation and injection into the venturi.
The operation of the carburetor shown in Fig. 2 is as follows. The methods used to deliver the primary fuel from compartment G into the venturi are more or less conventional and it follows from the usual consideration that the quantity of primary fuel thus introduced into the venturi is a function of the mass travel of air through the venturi so that the desired proportionality between induced air and injected primary fuel is thus set up.
If it is assumed that the primary and secondary fuels are delivered to the needle valves B!) and BI at the same pressure, which pressure will be hereinafter referred to as storage pressure, then the pressure in compartment G is less than the storage pressure by an amount which corresponds to the pressure drop across the needle valve 80. This pressure drop is a function of the rate of flow of the primary fuel and the constants of this function may be varied by adjustment of the needle valve 86.
The valve BI is constantly open an adjusted amount. However, in the absence of an substantial flow of secondary fuel through the valve 8i and into compartment F, due to closing of valve i5, 71, the pressure in compartment F would be substantially storage pressure. Under these conditions the pressure unbalance across the diaphragm '15 would cause the discharge nozzle to open, thus permitting flow of secondary fuel through compartment F and into the induction pipe Ell via member 65. This flow of secondary 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 such that the pressure drops across the two needle valves become equalized. The rate of flow of secondary fuel is thus proportional to the rate of flow of primary fuel 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. lihe relative proportions of primary and secondary fuels may be adjusted to any desired value by suitable setting of valves 88 and/or 8|.
Differences in source pressure may also be taken care of by appropriate adjustment of the valves and 8! provided that under conditions of no fuel flow the discharge valve 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 pring 93 adapted to exert a slight closing force on the diaphragm 15. This is not only of value in insuring the closure of the discharge valve when the engine is not in operation, but it also insures that the primary fuel forms the principal constituent of the combustion mixture at very slow rates of operation. At low idling speeds the Venturi aspiration is a somewhat more accurate metering means than is the diaphragm-operated discharge valve.
In some respects I consider the carburetor shown in Fig. 2 as preferable to that in Fig. 1. It is more simple in construction and offers less problems in valve and diaphragm alignment. Furthermore, the Venturi metering at low fuel rates is a much more sensitive method of control in idling or low speed operation than is the control of the discharge Valve by the restricted orifice 3! of Fig. 1. The use of two fuels also offers great flexibility of operation since one of the fuels may even be gaseous. A safety factor is also present in the operation of the carburetor shown i Fig. 2 since even if the secondary fuel system becomes clogged or inoperative, low power motor operation can still be maintained on the primary fuel alone.
These are relatively small distinctions, however, in comparison to the very important advantageous and novel characteristics which are displayed by both carburetors in common.
Both carburetors are insensitive to variations in pressure during operation. An increase in pressure of the fuel or fuels which are supplied to the carburetor does not affect the metering. Also the metering remains unchanged by any variations in the pressure in the induction piping into which the fuel is discharged.
This latter 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 correspondare necessary to thus meter the liquids, the
metering being performed solely in response to the Venturi pressure. These carburetors may be aptly described as Venturi-controlled, injector type carburetors adapted to operate under high pressures.
Another important feature is that the effective metering is done by the discharge valve and at the point of discharge so that the metered liquid is immediately completely free to escape into the induction pipe. This is of particular advantage in using high vapor pressure fuels where the attempt to first meter a given quantity of the liquid and subsequently to discharge it through a pressure 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.
Many other advantages are also present in my carburetors, among which may be mentioned the 'full closure of the discharge valve when the engine stops, even though the fuel may be under very high pressure, the completely enclosed character of the carburetors whereby extraneous mat I ter is excluded, and the like. I
' The most important advantages of my carburetors become apparent, however, only when consideration is given to the question of fuel. Gasoline type carburetors, typically atmospheric pressure float-bowl carburetors, can be used only in connection with gasoline type fuels, i. e.', fuels containing little or no normally gaseous constituents and having a vapor pressure not appre-,
carburetorsfor gaseous fuels are adapted to work on the fuel only after it has been converted into the gaseou state, which requires that the liquefied gases used therewith, such as propane and combustion mixture.
butane, be substantially free from any heavier constituents which would not volatilize or which would interfere with volatilization. 1
With my type of carburetor sufiicient pressure can be imposed to keep normally gaseous constituents liquefied or in solution up to the discharge or injection point. Since the fuel is injected as a liquid without the requirement of prior volatilization, the presence of relatively nonvolatile. constituents in the liquid fuel is completely unobjectionable. Consequently, by the use of these carburetors there becomes available for use ininternal combustion motors a whole new class of fuels, namely, those fuels which contain sufficient normally gaseous materials to have avapor pressure substantially in excess of atmospheric and which may contain in addition very substantial proportions of fuel constituents whose vapor pressure is well below atmospheric or which are relatively non-volatile. i i
The composition and characteristics of such mixed base fuels, i. e., fuels containing constituents both of the normally gaseous and normally liquid types, will presently be discussed in greater detail, but in connection with the present question of carburetors, it is apparent that such fuels could not be used in conventional type carburetors and become available for use only through the special characteristics of the carburetors as above described.
Even when operating on a fuel containing only normally gaseous constituents such as propane or butane or a mixture thereof, my. method of carburetion presents great advantages over conventional. methods involving ,vaporization. In the first place,..my methcdeliminates the need for the bulky and difiicultly operable vaporizi units which have hitherto been necessary to convert all of the liquefied fuel into gas. ,Inrny method neither pressure nor temperature variations are of importance whereasin the prior handling of completely gasified fuel. it was necessary to maintain the density or the vaporizedjuel substantially constant in order to obtain the proper This requirement of uniform density in-the gas mixture required the use of isobaric and thermostatic devices to maintain the gas at constant pressure and temper,- ature, all of which become unnecessary in the present method. i A very important advantage accruing from my method of injecting the normally gaseous fuel constituents in liquefied or dissolved form arises from the fact that their vaporization takes place in .direct heat exchange relationship with the combustion charge whereby the latent heat of vaporization becomes available for cooling of the charge with resultant increases in; volumetric efficiency. The effects of a supercharger are thus obtained without any penalty of power diversion to a super-charging unit.
The direct exchange of the latent heat of vaporization with the sensible heat of the charge results in very high cooling efficiency, much greater than can be obtained by methods of indirect heat exchange; My carburetor is of value, however, even if it is desiredto maintain an indirect heat exchange relationship between the vaporizingfuel and the induced air. For example, in Fig. 2 the tubular member may be extended as a; longduct in. heat exchange relationship with the air moving through the pipe so that the vaporization of the. fuel in the duct cools'the-air indirectly. The vaporized .fuel may :then be injected; into the combustion cylinders independently of the air 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 flow of engine heat into the carburetor casing 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 reentrant discharge duct such as the tubular member 24 of Fig. 1 or tubular member 68 of Fig. 2. 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 in Fig. 2. If such pro-coolingof 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 dry gas carburetion will be apparent to one skilled in the art, although specific mention might here be made of the fact that my device is completely responsive to Venturi control and to Venturi mixing, whereas dry gas carburetors ordinarily require a mechanically movable valve to obtain fully eificient metering and mixing. Also, 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.
Several features of importance arise in comparing my method of carburetion with that normally employed in gasoline injection carburetors. In conventional gasoline injection carburetors the fuel is jetted as a liquid directly into the moving air stream. In order to increase the atomization and dispersion of the liquid fuel, use is usually made of a pulverizing nozzle or jet which tends in some degree to give a finer comminution of the liquid droplets in the air. With my method atomization, disruption, and dispersion of the fuel in the air are automatically had to a very enhanced degree. Because of the relatively high pressure under which the fuel is maintained up to the point of discharge, a large amount of energy proportional to the pressure drop across the discharge nozzle becomes available for disruption and atomization of the liquid fuel. Furthermore, immediately the liquid fuel containing normally gaseous constituents is released to atmospheric or sub-atmospheric pressures, a violent or explosive type boiling takes place which serves in very marked degree to further disrupt and atomize the remaining liquid.
This efiect is apparent even-though the remaining liquid contains a substantial proportion of relatively non-volatile constituents.
Other advantages incident upon the injection of high vapor pressure fuel are as follows. The almost immediate vaporization of the normally gaseous constituents insures very early mixing of the fuel and the air in the carbureti-on system whereby a very homogenous air-fuel mixture is obtained. The distribution quality of such a mixture is particularly good, each cylinderof the engine receiving a mixture of substantially the same composition.
The rapid volatilization of the normally gaseous constituents results in a lower temperature and increased density of charge mixture extending back substantially to the point of injection. The desirable inertia effects of the moving charge are thereby increased, which efiects are in addition to the above-mentioned increase in volumetric eiiiciency which is attributable to the increased density per se.
Another eifect which becomes apparent when the high vapor pressure liquid is injected in a direction parallel to the air flow, or substantially parallel, as provided for in the curvature of pipe 10 of Fig. 1 and by the .L-bend in member 65 in Fig. 2, is the ramming or inspirating effect on the air and fuel in the induction pipe, which effect arises both from the kinetic energ of the discharge stream, and its relatively large area of effective contact with the gases in the induction ipe as caused by the explosive gasification of the normally gaseous constituents immediately subsequent to injection, and which effect has as a consequence an inspirating eifect on air upstream from the point of injection and a ramming or supercharging effect on the fuel-air mixture downstream from the point of injection.
Fig. 3 is a cross-section of a flexible walled, vapor inflated fuel storage vessel for use in connection with liquid fuels having high vapor pressure generally and more particularly in connection with my mixed base, high vapor pressure fuels having vapor pressures in excess of atmospheric but not extending substantially beyond 20 or 25 pounds per square inch gauge at 70 This storage vessel has as its essential feature a closed or hermetically tight flexible envelope me which envelope is adapted to be inflated or distended and maintained in more or less rigid condition by the vapor pressure of the liquid contents kept therein. A rigid framework, suitably of latticed construction, is preferably provided to partially enclose the envelope 00. A cross-section of such a framework is indicated in Fig. 3, [Bl denoting a rigid bottom support, H12 denoting a rigid top support, and m3 and HM denoting rigid side members.
An outlet for the liquid content within the containing envelope IEZEJ is provided by means of pipe I35 which extends upwardly through the bottom rigid member i6! and transpierces the envelope at this point. The upper portion of the pipe IE5 is provided with a collar Hi6 and this collar is brought into sealing compression with the envelope I00 and the rigid member iiil by means of an external lock nut I01 which is threaded on the exterior portion of the pipe I05.
In case it is desired to withdraw gaseous fuel from the upper gas phase in the container H10 as when it is desired to use the gas as a primary fuel in connection with a carburetor such as is shown in Fig. 2, a gas Withdrawal means I08 similar in construction to that described for the withdrawal of the liquid may be positioned at the top or near the top of the container.
The Walls of the flexible envelope I may be constructed of any flexible material which is impervious to gas and liquids and which is not deleteriously acted upon by hydrocarbons and sim ilar fuels. Various synthetic rubber substitutes such as neoprene or duprene are satisfactory in this respect. A very advantageous form of construction of the flexible wall material is shown in Fig. 3a.. The wall there illustrated in cross-section is constructed of inner and outer sheets I619 and III) respectively havinga viscous or semi-plastic fluid III therebetween. I use for this plastic material compounds which are known to the art of self-healing, i. e., they will exude into any accidental perforations in the sheets IIIlor I89 and there harden so that the imperviousne'ss of the envelope as a whole is not injured by minor failures. Ihe approximate shape of the inflated container may be spherical, cylindrical, or any special shape required for use in a restricted storage space. I find a cylindrical shape of relatively long axial extension is advantageous in providing large capacity without excessive wall tension, and if desired a plurality of such elongated cylindrical flexible-Walled containers may be provided to increase further the ratio of capacity to skin tension.
Among the principal advantages of my flexible-walled, vapor inflated container are its ex-- treme lightness of construction and its resistance to fatigue under conditions of continued vibration, thus making it well adapted for'aerohautical service. The advantages of this container are best realized'with fuels having only a model ately high vapor pressure, for example, from 16 to 25 pounds per square inch gauge.
One of the principal objects of my invention is to moderate the vapor pressure of a fuel having a large proportion of normally gaseous constituents. One means of achievingthis object is to blend the normally gaseous constituents with normally liquid constituents adaptedto reduce the vapor pressure of the gaseous constituents, as disclosedmore fully hereinafter.
Another means for reducing the vapor pressure of the fuel as maintained in storage cons sts in the automatic control of the temperature thereof whereby the vapor pressure of the fuel be maintained within limits which permit the use of relatively light Weight equipment for the storage and handling of the fuel, this being a particularly important advantage in connectie-n with the use of this fuel inaircraft or light weight automotive vehicles.
In Fig. fl I have illustrated an automatic means for maintaining the vapor pressure of the fuel as stored within the storage vessel withinprescribed upper limits. Referring particularly to Fig. 4, I20 denotes a pressure-tight container thermally insulated on the exterior by a coating of insulation I2I, The liquid withdrawal means includes a pipe I22 arranged as a series of coils in heat exchange relationship with the liquid contents of the tank. One end of the coiled pipe I22 communicates with a short riser I23 which is adapted to, receive the liquid contents of the tank and which has an end portion shaped as a beveled valve seat. A conical valve member are is arranged to cooperate with the member 23 to form an adjustable valve means for thewithdrawal of the liquid fuel. The setting of this valve means is controlled by a pressure responsive diaphragm I25 which acts through areversing lever linkage I26 to restrict the valve opening when the pressures in thetank I20 are high, whereby the aperture afforded by the valve means is inversely proportional to the tank pressure.-
The other end of the coilmeans I22 communicates by means of a pipe I30 with the suction of a pump, suitably a vane type pump as denoted by the numeral I3I. The discharge from this pump, which represents the pressured fuel supplied the carburetor or other fuel utilizing means, may be passed through a heat exchanger or cooler I32 if desired.
The operation of this device is as follows. As the vapor pressure in the tank I28 increases due to an increase in temperature of the liquid fuel contained therein, the pressure diaphragm I25 effects a partial closing of the valve means constituted by members I24 and I23. The withdrawn fuel is correspondingly subjected to asubstantial drop in pressure as it traverses this valve means so that partial vaporization takes place in the coil I22. The latent heat of vaporization is abstracted to a large degree from the fuel remaining in theutank, whereby the latter is cooled. This condition endures until the liquid contents of the tank I253 have been cooled sufficiently that their vaporpressure is below a predetermined maximum value, which maximum value can be adjusted by modifying the characteristics of the pressure diaphragm I25 or the linkage between thisdiaphragm and the valve member I24. When the desired pressure level is reached, the valve member I24 'will have been retracted to a point Where further refrigerative effects are negligible. The fuel withdrawn from the pipe I30 during the refrigerating period will thus comprise a mixture of gas and liquid. This mixture is preferably re-pressured by the pump I3I to a pressure sufiicient to again completely liquefy the withdrawn fuel. If desired, the pressures requisite for this re-liquefaction can be considerably lowered by passing the discharge ofthe pump through a cooler I32 which serves to condense any vaporous constituents and abstract the heat of condensation.
This method of operation is essentially a method for removing excessive heat from the stored high vapor pressure fuel by withdrawing the heat with the withdrawn fuel. For static periodswhen no fuel is being withdrawn, further automatic internal refrigeration may be provided for by means of an adjustable pressure relief valve Hill which permits the escape of vapors when the pressure within the tank exceeds a value corresponding to the operative setting of the relief valve. This release of vapors causes further vaporization to take place within the tank, whereby the contents are chilled to the desired degree. The vapors thus permitted to escape may be either wasted or passed to a low pressure, vapor storage vessel, or re-pressured, cooled, and condensed for return to the storage vessel or. for immediate use as a liquid fuel as the case may be.
The pressure relief valve may be rendered in- 'operative when. its function is not desired by "closure ofa valve I 4| I may also employ a bi-phase fuel system in connection with the automatic pressure control in fuel storage tanks containing high vapor pressure fuels, which lei-phase system employs the principle of withdrawing fuel from the gas and/ or liquid phase and regulating the proportions of gaseous and liquid fuels thus abstracted in accordance with the pressurein the storage vessel, whereby the vaporous constituents are withdrawn preponderantly at more elevatedpressures so that he attendant vaporization and internal refrigeration of the fuel thereby effected is employed to reduce said high pressures.
This principle may be' used in connection with the operation of the carburetor shown in Fig. 2
by supplying the needle valve 8! from the liquid phase in the fuel storage tank, and supplying the needle valve 88 from the vapor phase in the same tank, and by furthermore making the setting of the needle valve 3! responsive to the pressures in the tank or in the fuel line, which may be readily done employing a conventional pressure responsive valve. The application of this principle is not limited, however, to use in such a dual phase carburetor and in the embodiment shown in Fig. the principle is shown embodied in a device which ultimately supplies a constant pressure, completely gasified fuel.
Referring to Fig. 5, an insulated storage tank ill!) is provided with withdrawal lines l5] and 152 for the vaporous and liquid constituents thereof respectively. The liquid flowing through the pipe i522 is completely gasiiied by a heating element before it is introduced into a valve box I54. The gaseous fuel withdrawn through the pipe l 5! is introduced directly into the valve box Hi l. Ihe ginally gaseous material and the originally liquid, now completely gasified, material are introduced into the valve box I54; by means of valve ports 55 and 556 respectively. The openings of these ports are reciprocally controlled by a douhie-ended valve member [51 the setting of which made responsive to a pressure bellows its by means of a fulcrumed linkage I 59, The gaseous contents of the valve box lot are withdrawn through a pipe 158 to a pressure reducing or constant pressure means means of a pipe Hi2 to the ultimate destination (not indicated) of the constant pressure, completely gasified fuel.
The operation of this device is as follows. The fuel preferably contains little or no non-volatile constituents. As long as the pressure within the fuel tank remains below the desired maximum operating pressure, the fuel is withdrawn largely as a liquid through the line I52, the valve member 55'! being in its uppermost position to effect substantial closure of the port I55. The pressure diaphragm or bellows l58 is adjusted to move the valve member i5! downwardly, opening the port I55 and closing the port I56, when the pressure in the tank, which is communicated without substantial change to the valve box, exceeds the desired maximum working pressure. Under these latter conditions the fuel withdrawal is made largely from the vapor phase in the tank I50, whereby vaporization is caused to take place within the tank to obtain the desired internal refrigeration, thus again lowering the temperature and dependent pressure to within the desired operating range.
While I have shown the controlling valves in Figs. 4 and 5 as responsive to pressure, I may also make use of temperature responsive controls in view of the known interdependence of vapor pressure and temperature. Such temperature controls should be set in accordance with the vapor pressure-temperature curve of the particular fuel employed in order to maintain the pressure within the desired range.
By employing one or more of the above principies, the pressure requirements of the fuel storage tank and fuel system generally may be very greatly decreased, making possible a saving in construction weight. as Well as insuring the maintenance of safe operating pressures.
The fuels comprised in my invention are constituted by mixtures of normally gaseous constituents with normally liquid constituents and are intended for use primarily in liquid injection MI, and thence by fuel systems such as those described above. In general, the proportion of normally liquid constituents is sufficientl high to effect a substantial reduction in vapor pressure of the normally gaseous constituents, and, on the other hand, the proportion of normally gaseous constituents is sufficiently high to insure that the mixture retains in large degree the inherently advantageous characteristics of the normally gaseous constituents. Apart from the question of relative volatility, the normally liquid or relatively non-volatile constituents may also comprise such modifying agents as upper cylinder lubricants, knock suppressors, and the like.
As normally gaseous constituents I employ primarily the lighter hydrocarbons such as methane, ethane, propane, and butane, the unsaturated hydrocarbons, propylene and butylene, and the like.
The normally liquid constituents in general comprise liquids which are miscible with liquefled butane or propane or which are adapted to dissolve substantial quantities of methane or ethane at relatively moderate pressures. Another general characterization of these normally liquid constituents is that they are substantially less volatiie than the normally gaseous constituents. As examples, I may mention hydrocarbons boiling above 200 F., heavy ends from gasoline known commercially as naphthas, light lubricating oils such as are used for upper cylinder lubrication, and the like. I find that a naphtha having an initial boiling point of ZOO-300 F. and an end boilin point not substantially in excess of lGO" F. constitutes a Very excellent normally liquid constituent, although, if desired, these boiling ranges may be widened to embrace most or all of the fractions normally contained in gasoline.
I may also emplo non-hydrocarbon materials as my normally liquid constituent, particularly oxygenated materials such as alcohols, ketones, ethers, and the like, The normally liquid constituents may comprise in whole or in part compounds which are adapted to supply lubrication to the upper cylinder walls or to increase flame propagation rate, or to widen the range of mixtures having proper ignition characteristics, or to increase the'anti-knock rating, or to increase the latent heat of vaporization, or to prevent carburetor icing, or to prevent ring sticking, or to decrease the total fuel cost, or to serve in other known capacities for advantageously modifying the characteristics of the fuel. Since these fuels are to be stored under pressure and in the absence of air, I may readily employ constituents which are unstable in air, such as unrefined cracked gasoline which in the presence of air tends to oxidize and form gum, or mixtures of hydrocarbons and ethyl alcohol which tend to absorb water from air and separate into two phases.
As indicated above, the best results are obtained by using a normally liquid constituent which has a substantially lower vapor pressure than that of the normally gaseous constituent, for example, material having an initial boiling point of or 200 F. The mixture thus obtained has a substantial gap in boilins point from the normally gaseous constituent to the liquid constituent, which condition I find advantageous in at least many instances.
When employing a hydrocarbon distillate as the normally liquid constituent, I find in many instances that regard should be had for the end boiling point thereof, which for best results should new! not differ greatly from the end boiling points established as optimum for conventional gasolines, typically 400+30 F. Such a distillate may be either a heavy naphtha, having an initial boiling point of 200 or higher, or a typical gasoline fraction such as is readily available commercially. Very excellent high vapor pressure fuels may be made in accordance with my invention by blending a minor proportion, e. g. 30%, of a commercial type gasoline with a major proportion, e. g. 70%, of liquefied normally gaseous hydrocarbon such as butane and/ or propane.
I prefer to adjust the relative proportions of normally gaseous and normally liquid constituents on the basis of the vapor pressure of the resulting mixture since the optimum percentage proportions may vary according to whether, for example, butane or methane is taken as the gaseous constitutent and according to the character of the liquid constituent as well. I find, however, that the optimum composition in each instance will have substantially the same vapor pressure and hence this latter characteristic serves as a valuable criterion for adjusting the composition.
My preferred range of vapor pressures is from to 30 pounds per square inch gauge at 70 F. and within this range I find that about to pounds per square inch gauge at 60 F. represents the optimum vapor pressure corresponding to the optimum composition with the constituents concerned.
I find that a mixed base fuel having a vapor pressure of from 10 to pounds per square inch gauge or thereabouts, particularly from 15 to 25 pounds per square inch at 60 F. contains sufficientof the gaseous constituent to endow the mixture with advantageous characteristics. A combustible mixture of air and such a fuel will not form condensates in the intake manifold, will have a wide ignition range and a high anti-knock rating, will burn cleanly and without substantial formation of carbon, and will, when injected into the intake manifold, refrigerate the charge sufficiently to give the effect of increased volumetric efficiency and increased density discussed hereinabove. I find, furthermore, that the atomization of the liquid fuel by the initial very rapid vaporization of the gaseous constituent is displayed in completely adequate degree by a mixed base fuel having substantially the indicated optimum vapor pressure.
I also find that by employing sufficient normally gaseous constituents to bring the vapor pressure within the optimum range, the concentration of completely vaporized fuel in the intake manifold downstream from the point of injection is insured to be sufficiently high to be a substantial aid in the dispersion and/or vaporization of the relatively less volatile constituents by effects of volume, velocity, and partial pressure.
While the indicated range of preferred vapor pressures is adequate to secure the described advantages, .and is furthermore low enough .to permit the use of relatively lowpressure storage vesselS and fuel systems, it is to be understood that my invention also extends to mixed base fuels of still higher vapor pressures. That is particularly true when fixed gases, i. e., gases not readily liquefiable, typically methane and ethane, are to be used as the normally gaseous constituents of the blend. Such blends will exhibit the desired characteristics when sufficient fixed gas has been added to bring the vapor pressure within the preferred range, but the weight per cent of fixedgas dissolved in such a blend will remain relatively low. If itis chiefly desired to use as much fixed gas as possible, in View of its very low cost, then recourse may be had to much higher vapor pressure blends, e. g., blends having a vapor pressure of pounds per square gauge or higher at 60 F., the increased mechanical costs for very high pressure fuel systems being offset by the lower cost of the fuel per se.
Mixed base fuels of the indicated composition have substantially all of the advantages incident to the use of completely gaseous fuels and at the same time permit the co-use of some normally liquid constituent of lower quality or specific action. These advantages are obtained, moreover, without penalty of imposing high liquefying pressures on the fuel system since my fuels may be completely liquefiable at from 10 to 30 pounds per square inch gauge :and preferably at about 20 pounds per square inch gauge, which may be contrasted, for example, with the vapor pressure of liquid propane, which at 70 F. has a Vapor pressure of about pounds per square inch gauge. The advantageous characteristics of these fuels are'fur-ther typified by the following examples:
Example 1.--Three volumes of a first structure gasoline were blended with seven volumes of liquefiecl gas consisting of 70% butane and 30% propane. The resulting blend had a vapor pressure of 24 pounds gaugeat 60 F. When used in a carburetor similar to that shown in Fig. 2 (cmploying a small proportion of primary fuel from the gaseous phase of the storage vessel), the effective knock rating was Well in excess of 100. No knock could be obtained even when using a compression ratio of 8.5 to l, and a20% increase in maximum power was obtained relative to the maximum power obtainable using gasoline in a conventional carburetor. Relative to gasoline, fuel consumption was roughly the same on a gallonage basis, substantially less on a weight basis.
It Was also found possible to change abruptly from idling to openthrottle operation under full load without causing the stalling or misfiring which this operation induces in conventional gasoline fueling. Formation of carbon and crankcase dilution were found to be negligible.
Example 2.Equal volumes of third structure gasoline (knock rating approximately 60) and butane were mixed to give a blend having a vapor pressure of approximately 15 pounds gauge at 60 F. The calculated knock rating of such a blend is about 72,, but in actual engine tests the effective knock rating was found to be about 90, which enhancement was due, at least in part, to the inherent refrigeration of the combustible charge. In spite of the low manifold temperatures, high gasoline content, and relatively low vapor pressure, no indicationscould be obtained of manifold condensation.
Example 3.--1A blend of three parts of ethyl alcohol and seven parts of liquefied gas (70% butane, 30% pro-pane) was. prepared and was found to have a vapor pressure and operating characteristics similar to those discussed in Example 1.
Example 4.-A blend of four parts of a petroleum naphtha boiling from 200 to 400 F, with 4.9 parts of butane and 2.1 parts of propane was found to have a vapor pressure and operating characteristics intermediate those of Examples 1 and2.
Example 5.--Compressed ethane was introduced into gasoline until the gauge vapor pressure of the ethane-gasoline solution was (a) thirty 19 pounds and (b) one hundred andfifty pounds. Both (a) and (b) showed'very substantially improved operating characteristics relative to the gasoline alone, the most pronounced'improvement being obtained with fuel (1)).
Several factors cooperate to make such fuels particularly advantageous for use in aircraft. Inthe first place, their relatively moderate vapor pressure makes possible the use of relatively light storage vessels, as contrasted, for instance, with the type of pressure cylinders required to store mixtures of butane and propane commercially available. In the second place, the weight of the total load including fuel is less than would correspond to a quantity of gasoline equivalent on a mileage basis and stored in conventional gasoline containers. This latter feature arises from the fact that the density of the liquefied, normally gaseous constituent is very much less than that of gasoline although equal volumes of my mixed base fuel and of gasoline will give about the same mileage due to the greater efficiency with which the former can be used.
It is to be understood that the details of the above examples are intended as illustrative rather than limitin and that various modifications of my invention may be practiced without departing from the essence of my invention as defined by the scope of the appended claims.
I claim as my invention:
1. Ina device for introducing high vapor pressure'fuel into an air passage of an internal combustion engine, the combination of: a fuel metering means; means for supplying liquid fuel under liquefying pressure to said metering means; and
means for at least partially vaporizing the metered fuel in the absence of air and in heat interchange relationship with the liquid fuel belllg supplied to said metering means, whereby the high vapor pressure fuel is cooled ahead of said metering means to insure its complete liquidity when reaching said metering means.
2. In combination with an air passage of an internal combustion engine through which air is supplied to said engine: a two-phase carburetor means for simultaneously supplying both liquid and gaseous fuels to said passage during normal operation of said engine; and means for automatically stopping the supply of said liquid fuel to said passage during idling conditions of said engine while continuing the supply of said gase ous fuel during such idling conditions.
3. In a device for introducing fuel into an air induction passage of an internal combustion engine, the combination of: means for continuously delivering a first portion of said fuel to said air passage and for varying the rate of flow of said first portion of fue1 to be substantially proportional to the mass rate of fiow of air in said air induction passage, said means including a restricted orifice; means for continuously delivering the remaining portion of said fuel to said air passage at all engine loads above idling; and means responsive to the pressure drop across said restricted orifice for varying the amount of said remaining portion of said fuel delivered to said air passage to be substantially proportional to the rate of fiow of said first portion of fuel to said air induction passage.
4. In combination in a device for introducing fuel into the air passage of an internal combustion engine: means for delivering a first stream of fuel to said air passage; means for delivering a second stream of fuel to said air passage; a
diaphragm operated valve for controlling the delivery of the second stream of fuel to said air' passage; means including a restricted orifice in said first stream to produce a valve-opening reduction in pressure on said diaphragm which increases the magnitude of reduction in pressure with increase in the rate of fiow of said first stream; and means including a restricted orifice in said'second stream to apply a valve-closing reduction in pressure on said diaphragm which increases the magnitude of reduction in pressure with increase in the rate of flow of said second stream, whereby the rate of flow of said second fuel stream is maintained substantially proportional to the rate of the first stream.
5. A method of obtaining a supercharging effect in the operation of an internal combustion engine, which method includes the steps of: delivering a stream comprising a mixture of air and fuel to said engine; and introducing into said stream of admixed air and fuel before the same is burned in said engine a pressure-liquefied fuel having a vapor pressure at F. above 10 lbs/sq. in. and containing substantial quantities of pressureliquefied normally gaseous constituents which flash into vapor'at the pressure of said stream, said liquid fuel substantially instantaneously vaporizing in said stream to extract therefrom the latent heat of vaporization. I
6. A method of supercharging an internal combustionengine, which m thod includes the steps of: moving toward said engine in a confined space a stream comprising air; and discharging into said stream droplets of liquefied normally gaseous fuel in controlled amount to obtain a "direct heat exchange between said fuel and said-air as said fuel vaporize's, said liquefied normally gaseous fuel having a vapor pressure above 10 lbs/sq. in. at 60 F. and said stream of air being at a sufficiently low pressure to insure substantially immediate flash-vaporization of the fuel in the liquid droplets discharged into said air stream.
'7. A method of forming a'fuel-air mixture for burning in a combustion space, which method includes the steps of: delivering air to said combustion space; cooling said air by at least partially vaporizing a liquefied normally gaseous fuel in indirect heat-transfer relationship therewith; and thereafter "delivering said fuel to said combustion space.
8. A method of operating an internal combustion engine, which method includes the steps of: delivering a stream of combustion air to said engine; continuously introducinga gaseous fuel into said stream of air at one position; and continuously-introducing a liquid comprising liquefied normally gaseous fuel intosaid stream at another position and in amount substantially proportional to the amount of-gaseous fuel continuously introduced into said stream of air.
9. A carburetion method, which method includes the steps of: moving a confined stream of air through a passage; supplying to said stream of air atdifferent axially-spaced positions a gaseous fuel and a liquid fuel; 'controllingthe supply of one of said fuels in response to the amount of air moving through said passage; and controlling the supply of said other fuel in response to-variations in supply of said first-named fuel and to make the supply of said other fuel substantially proportional to the supply of said one fuel.
10. A fuel system for internal combustion engines, comprising in combination: a pressure storage vessel adapted to contain a lower body of liquid fuel "andan'upper body of vaporized fuel means forming a charge-induction passageway for supplying admixed air and fuel to the engine; means communicating with the lower portion of said vessel for delivering liquid fuel to said charge-induction passageway; means communieating with the upper portion of said vessel near the top thereof for delivering gaseous fuel to said charge-induction passageway and flow-control means responsive to the amount of one of said fuels delivered to said charge-induction passageway for controlling the amount of the other of said fuels delivered thereto.
11. In a carburetion device for the simultaneous use of two fuels in the formation of a combustible mixture, the combination of: means defining a first restricted orifice for one of said fuels; means defining a second restricted orifice for the other of said fuels; means for supplying said fuels respectively to said first and second orifices at proportional pressures; walls defining an air passage; means for delivering said one fuel from said first restricted orifice to said air pasage; a flow-controlling valve means receiving the fuel from said second orifice and delivering same to said air passage; and means responsive to the pressure of said first fuelat a position beyond said first orifice and responsive to the pressure of said second fuel beyond said second orifice for regulating said flow-controlling valve means.
12. In a carburetion device for the simultaneous use of gaseous and liquid fuels, the combination of means defining a first restricted orifice for said gaseous fuel; means defining a second restricted orifice for said liquid fuel; means for supplying gaseous and liquid fuels respectively to said first and second orifices at proportional pressures; walls defining an air passage; means for delivering said gaseous fuel from said first restricted orifice to said air passage in amount substantially proportional to the mass rate of flow of air therethrough; means for delivering liquid fuel from said second restricted orifice to said air passage; and means responsive to the amount of gaseous fuel delivered to said air passage for controlling the amount of said liquid fuel delivered to said air passage.
13. In a carburetion system, the combination of: walls defining an air passage through which moves a stream of air; a tubular member extending into said air passage for discharging fuel into said air to form a combustible mixture; a flowregulating valve means providing intake and discharge sides, said discharge side communicating with the interior of said tubular member; means for delivering liquefied normally gaseous fuel to said intake side of said flow-regulating valve means under pressure, said means including a fuel-supply passage and an orifice therein across which a pressure drop is developed by fiow of said fuel toward said intake side of said flow-regulating valve means; and means for increasing and decreasing the amount of said fuel discharging through said flow-regulating valve means in response to an increase and decrease in the amount of air flowing in said air passage, said normally gaseous fuel expanding and cooling in the absence of air upon flow through said flow-regulating valve means to cool said tubular member and discharging from said tubular member into said air stream while still comprising in part droplets of liquefied normally gaseous fuel which substantially instantaneously vaporize in said air stream to cool same, said fuel supply passage providing a portion upstream from said orifice and extending in heat-transferring relationship with the cooled tubular member to pre-cool said fuel at a position ahead of said orifice to insure complete liquidity of said fuel upon delivery to said orifice.
is. In a carburetion system for introducing fuel into an air passage through which a stream of air is moving, the combination of: a casing; a diaphragm means in said casing and cooperating therewith in defining first and second chambers separated by said diaphragm means; a metering orifice communicating with said first chamber; a metering orifice communicating with said second chamber; means for supplying two fuel streams respectively to said metering orifices at substantiallyequal pressures for flow respectively into said first and second chambers through said metering orifices whereby each fuel stream undergoes a drop in pressure during flow through its metering orifice, the reduced pressures acting on said diaphragm means; means for supplying fuel from said first chamber to said air passage in amount increasing and decreasing respectively with an increase and decrease in the amount of air flowing in said air passage; means for conducting fuel from said second chamber to said air passage to mix with the air flowing in said passage, said means including a flow-regulating valve means; and means for operatively connecting said flow-regulating valve means and said diaphragm means in a manner to move said valve means toward a more open position upon increase in absolute pressure in said second chamber and toward a more closed position upon increase in absolute pressure in said first chamber.
15. In a carburetion system for forming a fuelair mixture by use of fuel drawn from an enclosed storage vessel containing a body of liquid fuel in the lower end thereof and a superimposed body of gas in the upper end thereof in contact with said body of liquid fuel, the combination of: means forming an air induction passage through which moves a stream of air; means communieating with the upper end of said enclosed storage vessel for conducting a stream of gas to said air induction passage whereby the source pressure of said gas is the same as the pressure on said liquid fuel in said storage vessel; means for varying the flow of said gas to said air induction passage to be substantially proportional to the mass rate of flow of said stream of air moving through said air induction passage; fuel-delivery means communicating between the lower portion of said enclosed storage vessel and said air induction passage for delivering a stream of fuel to said air induction passage; and means associated with said fueldelivery means for maintaining the flow of said fuel to said air induction passage substantially proportional to the flow of said stream of gas to said air induction passage.
16. In a carburetion system for forming a fuelair mixture from fuel drawn from an enclosed storage vessel containing a body of liquid fuel and a superimposed body of gas comprising fuel vapor, the combination of: means forming an air induction passage through which moves a stream of air; means for delivering a stream of gas from said vessel to said air induction passage at a rate substantially proportional to the mass rate of fiow of air through said air induction passage, said means including a restricted orifice across which a pressure drop exists because of the flow of said stream of gas therethrough; means for delivering to said air induction passage a stream of fuel drawn from said vessel and including another restricted orifice across which a pressure drop exists because of the flow of said fuel and including an adjustable control valve for controlling the flow of said fuel into said air induction passage, said stream of fuel flowing through said adjustable control Valve after passing through said other restricted orifice; and means for automatically adjusting said control valve to maintain substantially proportional the pressure drops across said restricted orifices.
17. In a :carburetion system, the combination of: means forming an air induction passage through which moves a stream of air; two restricted orifices each providing an entrance side and. an exit side; means for delivering separate fuel streams at substantially equal pressure respectively to the entrance sides of said restricted 24 orifices to establish pressure drops across said orifices varying with the rate of fuel flow therethrough; a pressure-responsive valve providing a movable member, the pressures on the exit sides of said orifices being respectively transmitted to opposite sides of said movable member; means for supplying the fuel stream flowing through one orifice to said air induction passage at a rate varying with the mass rate of air 'flow therethrough; and means for supplying the fuel flowing through the other orifice to said air induction passage through said valve thereby controlling the rate of supply of this fuel.
ALBERT G. BODINE.