CA1067361A - Fuel vapor generator for an internal combustion engine - Google Patents

Abstract

FUEL VAPOR GENERATOR

Abstract of the Disclosure A fuel vapor generator in the form of a heat conductive member having an elongated U-shaped passageway formed through it.
The member is mounted at the exterior of a carburetor venturi. A
first open inlet end of the passageway extends through the venturi walls and receives atomized fuel from the main fuel nozzle and a portion of the incoming air. This fuel and air mixture is directed through the passageway where it is heated and the fuel is vaporized.
The fuel and air are drawn from the passageway and returned into the venturi at a location downstream from the main nozzle. A series of mesh screens extending across the passageway and spaced along its length assist in atomizing the fuel and assuring efficient conduction of heat to the entire mixture of fuel and air within the passageway.

Description

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: This invention relates to an improvement in conventional '.' carburetors used in conjunction with internal combustion engines.
'. The basic purpose of a carburetor is to mix a hydrocarbon fuel such ' as gasoline and air to forn a combustible mixture to power the~' .' pistons o-f an engine. A theoretically perfect carburetor should vaporizb.the -fuel completely as it is discharged at the main fuel ~ .
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nozzle of the carburetor and should maintain the vaporized con- ~
'; dition of the fuel:through its delivery to the engine cylinders. " :.
. Ho~ever, such.perfect vaporization exists only in theory.
10 Droplets:of unvaporized gasoline are considerably.heavier .' ' `' than the'gaseous mixture with which they are traveling. Their ..
`~ ; greater inertia causes them to continue in the diTection they are . .'' :
'~ moving when the mixture turns to follow a passage or to enter .
another passage. If possible, the.heavier particles continue ..
' straight ahead until they reach a dead end, rather than to mi~ke the '.
~: desired turns. .This results in the.center cylinders of a cylinder .' ':~
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` bank in many engines being run on a richer mixture than the end . ~ cylinders Better mixture distribution is one a.rgument in favor --: : of special multiple carburetors and specially "tuned" intake :
~:.'' 20 manifolds.
:~: Good m~xture distribution is important to smooth engine operation,.ev.en:thro~tle response, reasonable fuel mileage and ; . decreased exhaust emissions. Engine manufacturers to date have attempted to:correct this problem by heating the mixture of fuel :-. , ~ and air as it leaves the carburetor, thereby.attempting to more ~,.~,^
~ . completely vaporize the fuel m the mixture. This is typically :~ `` done by ro~ting exhaust gases.to heat the intake manifold. Heat .~ also is applied by many manufacturers by using a.heated air cleaner'.which sends ho~ air to the carburetor on a cold engine and '.
~ / 30 shortens the warmup time. ~.

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The area of the manifold that is heated is directly below the carburetor. This causes the mixture of gasoline and air to pass through a high temperature area immediately after leaving the carburetor. If the temperature is high enough, most of the fuel -~
~ill theoretically remain vaporized on its way to the cylinders. -The application of heat at the intake manifold does not work as effectively in practice as in theory. First, there is a large volume of air and fuel which must be heated as it passes rapidly along the intake manifold walls. The retention period for the mixture within the limited space available at the conventional intake manifold is very brief and there is not much opportunity -~
- to thoroughly heat the large volume of fuel-air mixture. Further-j .. .
; more, more heat will obviously be applied to that portion of the `~ mixture adjacent to the intake manifold walls than to the inner : ' -. .' .1 volume of the mixture.
Heated intake manifolds improve the operation of an engine, . ~ . .
but do not asslst in improving the power output. In a full throttle `~ ~ condition, an engine will develop more p~wer if the air-fuel mixture is cool rather than heated. A cool mixture is more dense than a warm mixture, which means that if the mixture is cool more gasoline and air can be packed into the combustion chamber than is possible when using a mixture that has been thinned out by heat. Thus for maximum horsepower, the engine must be warm and the mixture of fuel and gasoline must be cool.
The present disclosure utilizes a simple diverting heat ~ -J .. ~. .
exchanger to thoroughly vaporize all of the incoming atomized gasoline, along with a portion of the incoming air. It interrupts ~ -i, the normal flow of the mixture through the venturi of the carburetor, `
diverting it through an elongated passageway where heat is applied to the mix~ure to completely vaporize the gasoline. This is s, .

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preferable to heating of the new gasoline, which results in loss of evaporated gasoline and causes flooding of the engine when it is warm This device eliminates the need for the application of heat ; to the intake manifold. It allows the engine to be run on a cooler mixture than is practical under present engine design.
` The fuel vapor generator described herein is designed for use in conjunction with a conventional internal combustion engine that utilizes a carburetor with a main nozzle through which atomized fuel is discharged at the venturi of the carburetor. It structurally comprises a heat conductive member located at the exterior o the carburetor, having an elongated passageway with open inlet and ~ outlet ends. The inlet end of the passageway is positioned within ;~ the carburetor venturi at a location such that the atamized fuel leaving the main nozzle is directed into the passageway. Approxi- ~`
m tely one fourth to one sixth of the incoming air is also received within the inlet of the passageway. The fuel and air are pulled . through the passageway by vacuum pressure applied to the outlet end of the passageway, which projects into the carburetor venturi down-stream from the main nozzle. Mesh screens are interposed across the passageway to assist in heat conduction and to atomize and break up .~, .,~ .
~` any droplets of fuel. A jacketed heat exchanger can be utilized about . the portion of the member exterior to the carburetor to add heat as .; ~
` b~ required for proper vaporization of the fuel.
`~ The basic rnethod of vaporization relates to the withdrawing of the atomized fuel and a portion of the air entering the carburetor $ by directing the fuel and air into an elongated hollow mernber exterior ~ to the carburetor and thermally insulated from the carburetor so as - ~ to eliminate heating of the carburetor by the vaporizing procedure.
The atomized fuel and air is directed back into the venturi of the carburetor downstream fron the main nozzle. Heat is applied to the . ~ , . . ..
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fuel and air mixture at the exterior of the carburetor.

Fig. 1 is a sectioned view of the present device in relation to the venturi of a carburetor shown in schematic form in which the device is installed;
Fig. 2 is an exterior pictorial view of the device apart from a carburetor; and . .
Fig. 3 is an end view looking toward the inlet and outlet ends of the devic0 as seen from the left in Fig. 2.
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, A physical example of the device is illustrated in Fig. 1, ~ whi~h schematically shows the basic portions of a carburetor with - which the device is utilized. The simplified presentation of the ,, carburetor elements is presented only by way of illustration.
.` Obviously, the device can be utilized in conjun~tion w~bh~many .~ . .
~, different forms of existing or future carburetors which incorporate the basic elements discussed herein.
This device is designed for use in a carburetor having one or more venturis or throa~s through which a fuel-air mixture is `~
delivered to the intake manifold (not shcwn) of an internal combustion . ~ . . .
~ engine. The throat of the carburetor is generally indicated at 10.
r~ It includes a restricted area 11 commonly termed the '~enturi". A
~ main nozzle 12 directs fuel to the venturi in response to the vacuum ~ . -,, , pressure created by the venturi and operation of the engine. Fuel may be delivered to the main nozzle 12 by any conventional means, typically from a float bowl and main metering jet ~not shown). In many carburetors additional venturis exist and are located about the outlet of the main nozzle 12. Thes0 should either be removed ;
or the main nozzle replaced by a more simplified tube as illustrated in Fig. l. In any respect, the main nozzle 12 should direct the ~`
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incoming fuel to the inlet of this device as discussed below.
The device i~self basically comprises a hollow tubular member 13 having an elongated interior passageway, illustrated as being substantially U-shaped. The passageway could obviously have other configurations and might be coiled, curved or bent in order to properly fit within the existing space surrounding the carburetor and engine. Ilowever, a simple elongated straight passageway having a U-shaped configuration is both practical and useful.
` In the illustrated device, the hollow tubular member 13 is fabricated from cylindrical tubing. It has a subskantial length .
with respect to ~he width of the venturi 11 ~o provide a relatively long passageway through which the fuel must pass. Member 13 is bisected by a center plate 14 that extends across its full width.
;`~ Plate 14 terminates sho~t of an outer or closed end 15 of member 1,, .
13. It therefsre defInes an elongated U-shaped passageway extending ~`~ across the top of the device from an open inlet end 16 to outer end ~ ~ 15 and back along the lower portion of member 13 to an open outlet ;
- 17.
. . .
~ ``. When the device itself is mounted at the exterior of the , . ~ .
`~ 20 carburetor3 the inlet and outlet ends 16, 17 are projected into the ~
; , . :, `t carburetor venturi or throat. They are formed at opposite oblique angles with respect to the axis of the member 13, so as to entrap ;~
a portion of the incoming air in the inlet end 16 and so as to present a larger discharge area for appli.cation of engine vacuum to the outlet end 17.
~ The object of this device is to heat fuel discharged from ;J the main nozzle 12 carried within a portion of the incoming air entering venturi 11 to a temperature adequate to boil or vaporize . any remaining liquid droplets of fuel in the mixture. The conduction o heat is accomplished by construc~ing the walls of the passageway S- ,. , r '1 ; .

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within member 13 from heat conductive material, such as copper or aluminum. Heat transfer is enhanced by use of a series of metallic screens of relatively fine mesh, directed across the full width of the passageway as it leads away from the intake end 16 and to the outlet end 17 of member 13. The screens 18 also assist in more ccmplete vaporization of liquid fuel by physically breaking up larger droplets of fuel as they pass through the fine mesh. Screens 18 should also be constructed of heat conductive material such as copper or aluminum. The materials used in the device must also be chemically inert to hydrocarbon fuel so as to not decompose during use.
As the fuel and air mixture pass along the elongated passage-way between intake end 16 and outlet end 17, it must be heated to a temperature adequate to vaporize the remaining gasoline droplets.
This heat might be applied directly due to the proximity of the `
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device to o~her heated portions of the engine with which it is ~ utilized. A heat exchanger as such might not always be required. ~ -;~ However, for more universal application~ it is desirable that an enclosing jacket 20 be mounted about the member 13 to direct a heated fluid about the exterior walls of member 13 during use of ~,~ the device. As illustrated, the jacket 20 is a cylindrical tube having an enclosed end 21 spaced from the end 15 on member 13 and -~ sealed along its end adjacent to the carburetor. Inlet and ou~let connections 22~ 23 are provided for reception of cooling water ~
utilized in operation of the engine, heated exhaust gases or other ~ -- l available heated fluids. They should be at a temperature of about 160F. Such fluid is circulated through the jacket 20 continuously .:: .~ . .
~ ë~ during use of the device.
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The device should be thermally insulated from the carburetor itself. Since heat is applied to the device, it is desirable that , . ~ : . -,~
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lQ673~?1 insulation be utilized to prevent the application of heat to the walls of the carburetor. Such heat would tend to evaporate liquid fuel in the float bowl (not shown), which might flood the engine when it is running warm. Such evaporation is also undesirable when the engine is at rest, since it makes initial starting of the engine difficult when the bowl is dry. Thermal insulation can be provided in the form of a surrounding bushing 24 that mounts member 13 through the walls of venturi 11. Auxiliary brackets 25 (Fig. 1) can also be utilized to mount the device to the carburetor as necessary. The .~ .
~; 10 brackets 25 should also be constructed by way of a thermal insulating bushing o~ other insulating structure.
; j This device can be installed on existing carburetors by simply drilling a single hole through the body of the carburetor to inject the inlet and outlet ends of the device into the venturi, with ; inlet end 16 in direct communication with the outlet of main nozzle ~ -12 and outlet end 17 located in the venturi or throat of the carburetor ~; downstream from the outlet of main nozzle 12. The bushing or insulator ~'~ 24 can be in the form of a resin or plastic cement utilized to secure the member 13 to the walls of the carburetor. The size and shape of -~
the device? varies according to the amount of ~uel needed and the space available for installation at the exterior of a particular ~ ~ .. ..
carkuretor. The rich or lean quality of the fuel-air mixture is easily adjusted by positioning inlet end 16 in venturi 11. By directing main nozæla I2 further into inlet end 16, and by moving outlet end 17 further into the carburetor, more vacuum will be exerted through the passageway of the device, thereby drawing additional atomized fuel * om main nozzle 12 into inlet end 16 of member 13. Proper adjustment will divert about one fourth to one sixth of the incoming air into inlet end 16. The member 13 can be fixed in place permanently or ,~ 30 can be releasably mounted so as to be axially adjus??table as desired.

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Figs. 2 and 3 show further structural details of an actual working model of the device apart from a carburetor. The same numerals utilized in Fig. 1 are applied to these figures to designate the various elements of the device.
This invention arose from the experience of the inventor in installing and maintaining liquid propane gas systems for warehouse vehicles and operation and maintenance of a refrigeration plant.
This experience with vaporization of gases is now directed to the vaporization of gasoline for use in an internal combustion engine. -10 When using liquid propane, the resulting gas must be vaporized as ~
; completely as possible so as to be efficient for engine operation. ;
In refrigeration systems, the usual Freon gas must also be vaporized for efficiency. The present invention resulted from an effort to ;~ -build a device that would vaporize gasoline as completely as possible ;
to provide better combustion and fewer exhaust emissions.
` The development of this invention followed initial experi-;`j mentation with use of an electric heat coil in the booster venturi ~ -`1 of a carburetor. This failed because it is practically impossible ~, ... .
to vaporize as much liquid fuel as is needed for typical automobile ~- ;
engines in such a small area. The heat also was detrimental because .` of the resulting heat transfer to the carburetor itself. This caused : ~ rapid evaporation of the gasoline in the carburetor bowl, releasing .~
the hydrocarbons into the air after e-ngine shutdown and leaving the ~ carburetor bowl empty. The engine was therefore exceptionally hard ; ~ to start without excessive cranking power. Other proposed heat exchangers were studied which applied heat inside the carburetor, around the carburetor throat, or between the carburetor and intake ` ~ manifold. However, such heat application is self-defeating because the fuel-air mixture is expanded so substantially as to cause a lower '!
air-fuel ratio and a mixture that is too lean for high power operation `~' ' . ' ' ."

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of an engine.
The theory of this disclosure is to provide complete com-bustion by complete vaporization of gasoline mixed with cooled con-densed air, which will result in even distribution o-f the complete mixture to the cylinders. Realizing that this would not be accom-plished within the carburetor, it was decided to design a fuel vapor generator that would re-route the flow of -fu~l and a por~ion of the incoming air which would stherwise have passed directly through the ~ -~
venturi of the carburetor. This partial mixture is directed into passageways or tubing to the exterior of the carburetor and through ,: ~ ~ . .
~` a heat exchanger which might include a series of screens. It is - ~ returned as vaporized fuel to the venturi, l~here it is mixed with ':f,'' cool incoming air. By use of this device, a much larger area or volume is provided in which to vaporize the fuel and need for heat in the intake manifold is eliminated. A cooler fuel-air mixture flow to the cylinders results in a higher air-fuel ratio at idle, thus educing exhaust hydrocarbon~.
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Several items contribute to the rapid evaporation and vaporization in this device. First, the vacuum applied from the venturi of the carburetor, which draws fuel and air through the ` elongated passageway permits boiling or vaporization of the liquid i;~ .~.
at lower temperatures. Next, the series of screens atomize the drop--lets of gas and assure more intimate conductive heat transfer * om ,. ~; . ...
the device to the liquid g~soline. Third, the conductive heat transfer to the passagewa~ and screens from an exterior source of heat, which might be a heated fluid (hot water or exhaust gas) surrounding the elongated passageway exterior of the carburetor provide additional heat needed for vaporization. Exterior heat is necessary to co~nter- -act cooling action due to vaporization of fuel which would othe~wise ,; .- .:: .
~ ~" 30 tend to condense the fuel as fast as i~ is vaporized.
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~ Upon installation of the device in existing automobile ; engines, substantial gains in gasoline mileage have been demonstrated without loss of acceleration ability. An analysis of the engine opération has shown an increase in the air-filel ratio in comparison , ~ .
to normal engine and carburation settings. Analysis also has shown ,.
- more even distribution of the vaporized fuel to all cylinders at high speed and high power operation. There is also a definite gain in horsepower at higher speed engine operation. After rapid accel-eration and succeeding deceleration in a conventional engine, large - 10 amounts of llquid fuel are trapped in the intake manifold, resulting in a high percentage of hydrocarbons which are lost through the -;
exhaust system. With this apparatus in use, it has been demonstrated that vaporization of the fuel occurs to such a degree that a lesser percentage of hydrocarbons is trapped in the intake manifold upon such~deceleration.
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;`'~ To summarize the advantages of the device, one principal ~``i advantage is the ease o-f installation on most existing carburetors.
~` Furthermore, the device can readily be incorporated into the design , ~ .
of new carburetors, either a~ an integral part of the carburetor or as a separable accessory. There are no moving parts in the product j : .
and no main~enance is required to keep it operating properly. By ~! re-Tauting the fuel-air mixture to the exterior of the carburetor9 ~` the device provides increased volume in which to vaporize the fuel ~ beyond thait which would o~herwise be available wi~hin the carburetor.
Z~ '~ As an example, a six inch member provides a passage twelve inches ~ ~ ~ long for vaporizing fuel. The device takes advantage of heat that

2.'~ is readily available fr~n the engine itself or from the cooling ~j ,,~ , . system or exhaust system of the engine. It can be readily adjusted by axially positioning it for a rich or lean mixture. It vaporizes the fuel at the carburetor and eliminates the need ~or heat at the .. .' - 10 -, , .,s ~ , , . ,,, ., . ,. , .. ,-, ., .. ,, ,. ,.. ,, . ,, ;. , ,, , . -- ~g)Ç;~ 6 1 intake manifold. A lower temperature thermostat can thus be used in the cooling system, permitting the use of cooler air for the engine to provide an increased air-fuel ratio. This results in a cleaner burning engine, fewer emissions, greater mileage and longer engine life.
Modifications can obviously be made with respect to the structural features specifically illustrated and described above.
For these reasons, only the following claims are intended to limit and restrict the scope of the invention disclosed.
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Claims (8)

The embodiment of the invention, in which an exclusive property or privilege is claimed is defined as follows:

1. A fuel vapor generator for an internal com-bustion engine including a carburetor that has a main nozzle with an outlet through which fuel is normally discharged into a venturi through which the fuel-air mixture is drawn into an intake manifold, the fuel vapor generator comprising:
a hollow tubular member having interior walls which form a continuous passageway doubled back upon itself in an elongated configuration, the passageway terminating at open inlet and outlet ends located adja-cent to one another;
mounting means adapted to fix the member to the exterior of a carburetor with the passageway of the member leading to the interior of the carburetor through the walls of the carburetor venturi for locating the inlet end of the passageway adjacent to the outlet of the main nozzle of the carburetor and across a portion of the venturi and for locating the outlet end of the passageway at a location downstream from the outlet of the main nozzle of the carburetor to thereby direct the fuel and a portion of the air entering the carburetor through the passageway;
and means for applying heat to the walls of the passageway intermediate its respective inlet and outlet ends.

2. A fuel vapor generator as set out in claim 1 wherein said last-named means comprises a fluid receiving jacket surrounding the member remote from its inlet and outlet ends for circulation of heated fluids between the member and jacket.

3. A fuel vapor generator as set out in claim 1 wherein the mounting means comprises a thermal insu-lating bushing adapted to be interposed between the hollow member and the carburetor.

4. A fuel vapor generator as set out in claim 1 further comprising:
a series of mesh screens each extending fully across the passageway, the screens being spaced apart from one another along the length of the passageway.

5. The fuel vapor generator as set out in claim 1, wherein said last-named means comprises an enclosed jacket surrounding the portion of the tubular member remote from its inlet and outlet ends, said jacket including inlet means and outlet means for cir-culation of heated fluid between the interior of the jacket and that portion of the exterior of the hollow tubular member enclosed by the jacket.

6. A fuel vapor generator set out in claim 1, wherein said hollow tubular member comprises:
an elongated cylindrical metal tube having a cap across one end and being open at its remaining end;
and an elongated plate extending across the interior of the tube from its open end to a location spaced inwardly from the cap.

7. The fuel vapor generator set out in claim 1, wherein said hollow tubular member comprises:
an elongated cylindrical metal tube having a cap across one end and being open at its remaining end;
and an elongated plate extending across the interior of the tube from its open end to a location spaced inwardly from the cap;
said fuel vapor generator further comprising a cylindrical tubular jacket surrounding the one end of the tube and extending along a substantial par-t of the total length of the tube, said jacket being coaxial with the tube and spaced outwardly therefrom, the jacket being sealed about the tube at its end facing the open end of the tube and having inlet means and outlet means for cir-culation of heated fluid material between the interior of the jacket and that portion of the exterior of the hollow tubular member enclosed by the jacket.

8. In a carburetor for an internal combustion engine wherein the carburetor has a main nozzle with an outlet through which fuel is discharged and a venturi through which a fuel-air mixture is drawn into an intake manifold;
the improvement in a fuel vapor generator comprising:
a hollow tubular member having interior walls which form a continuous passageway doubled back upon itself in an elongated configuration, the passageway terminating at open inlet and outlet ends located adja-cent to one another;
mounting means for fixing the member to the exterior of the carburetor with the passageway of the member leading to the interior of the carburetor through the walls of the carburetor venturi, thereby locating the inlet end of the passageway adjacent to the outlet of the main nozzle of the carburetor and across a portion of the venturi and locating the outlet end of the passageway at a location downstream from the outlet of the main nozzle of the carburetor to thereby direct the fuel and a portion of the air entering the carbur-etor through the passageway;
and means for applying heat to the walls of the passageway intermediate its respective inlet and outlet ends.