US2314580A - Carburetor - Google Patents

Description

March 23, A1943. o. L. GARRr-:TsoN

CARBURETOR Filed Sept. 16, 1941 4- HIV mm ,/A w Y Bum Patented Mar. 23, 1943 CARBURETOR Owen L. (rarretson,V Detroit, Mich., assignor to Phillips Petroleum Company, a corporation of Delaware Application september 16, 1941, serial No. 411,061

(ci. zal- 11i .1 Claim.

This invention relates to a carbureting device. More particularly it' relates to a carbureting device for use with internal combustion engines wherein very' volatile, or high vapor pressure hydrocarbons or liqueed petroleum gases may be used as the fuel. The present invention is particularly adapted to the use of high pressure fuels such as natural gasoline or any other fuel which may contain a mixture of hydrocarbons which separate into gaseous and liquid phases at normal temperatures and pressures. In fuels of the aforementioned type the gaseous phase ordinarily contains a preponderance of propane, butane, or mixtures thereof which are known to possess high anti-knock value. The gasoline is ordinarily stored under pressure in tanks so that the lighter normally gaseous constituents are liquefied and in admixture with the relatively heavier and normally liquid constituents.

An object of this invention is to provide a method and apparatus for carbureting very volatile or high vapor pressure liquid fuels or even liquefied petroleum gases for internal vcombustion engines.

Another object of this invention is to provide a carburetor of simple design, with few adjustments for use with high vapor pressure liquid fuels.

Still another object of this invention is to provide a carburetor for use with high vapor pressure liquid fuels lwhich will not permit undesirable evaporation or ebullition commonly called vapor lock within the normally liquid containing portions of the carburetor.

Yet another important object of the invention is to furnish a carburetor for use with high vapor pressure fuels for automotive and aircraft engnes which will be sensitive and rapid in re,- sponse to acceleration.

Still other objects and advantages will be apparent to those skilled in the art from a careful study of the following detailed description.

The gure represents one embodimentof my invention directly applicable for use with internal combustion engines where high vapor pressure hydrocarbons or mixtures thereof are used as fuel.

Referring to the figure, numeral l represents the air inlet in which air flows in the direction as indicated by the arrow. Theair'may come directly from the atmosphere or through an air cleaner, `not. shown, the ow being caused by suc'- tion from the intake manifold of the engine. Venturi tube 2, hereafter called venturi, is installed inthe air inlet pipe l just previous in terms of direction of air flow to the butterfly throttle valve 3. Passing through the thickened side wall of venturi 2 is tube 4 for communication between air inlet l and chamber 'l of my carbureting device. Tube 5 enters the air inlet at 6 and the end of said tube 5 within the air inlet tube is open and said open end points in the direction of air now.

Diaphragm 8 separates an upper diaphragm casing 'I2 into two chambers 'l and 9. Chamber l is a chamber' of relatively small volume, while chamber 9 may be of essentially any relative volumev that'is, vsmaller or equal to chamber 'l, or even larger. Ordinarily I construct said chamber S somewhat larger in volume than chamber l, though it need not necessarily be so. Vent l0 is a small opening or vent connecting chamber 9 with the atmosphere in order to maintain chamber 9 at atmospheric pressure at all times or it maybe connected to the air tube on the upstream side of the venturi so as to maintain an equal pressure in chamber 9. Spring Ii is attached to the top center of diaphragm 8. and the tension ,or compression on said spring may be increased or decreased by turning the adjustment screw I3 in the proper direction. Cover i4 is for the purpose of excluding dirt, water or other foreign mattei` from the tension adjuster I3 and to give a pressure tight seal. To the underside of diaphragrn 8 is attached in a conventional manner push pin l5, the bottom end of which is attached also in a conventional manner to diaphragm Il. The push pin need not be attached to the diaphragms but may be easily.. held therebetween. Compartment i8 is separated from compartment i9 in diaphragm casing 32 by the above mentioned diaphragm Il. l

The lower plate portion 2i of the upper diaphragm casing l2 and the upper plate portion 22 of the lower diaphragm casing 32 form respectively the top plate and bottom plate of chamber or compartment 2B. The plate 2l contains a bearing or guide i6 for push pin i5. The said I` bearing or guide is intended to permit free vertical movement of the push pin l5 and yet be suf ficiently close fitting to prevent leakage of fluid from chamber 20 to chamber l.

To the push pin i5 is attached valve 24, which when in contact with seat 23 prevents flow of liquid from chamber i9 to chamber 2li.

Line 25 is the fuel line connecting the pressure fuel tank, not shown, and my carbureting device. The fuel line 25 divides and fuel passes through line 26 into the lower chamber i8 for maintenance of liquid pressure therein. The fuel for carburetion passes through tubing 27which is within pipe 28 for cooling purposes, needle valve 29 and thence into chamber I9. Pipe or tube 28 serves as an intermediate passageway between chamber 20 and tube 5. Needle valve 30 is located in an exit from fluid chamber 20, the fuid passing from chamber 2D through said needle valve 30 through line 3| and thence into the air inlet tube I on the downstream side of the butterfly valve 3.

A washer 33 on valve 24 permits a sealing engagement between the valve and the seat 23. A compression spring maybe interposed between the end of valve stem I5 and diaphragm I I to -avoid pumping in the chamber I8 and increase of volume in chamber I9.

In the 'operation of my invention. I am able to use such hydrocarbon fuels as liquid butane, natural gasoline or fractions thereof or mixtures of butane with natural gasoline or fractions thereof as well as ordinary gasoline to yield relatively high vapor pressure fuels. By high vapor pressure fuels I intend to include the use of such fuels which have vapor pressures greater than that of ordinary automotive gasolines. Ordinary gasolines may be employed with the use of tank pressuring means. In the use of such hydrocarbon fuels. they will be contained in the gas tight fuel supply tank at least under their own vapor pressure, and under certain conditions may be held under pressures greater than their vapor pressure to insure a flow of liquid from the gas-tight fuel tank to the carburetor and to prevent premature vaporization or vapor-lock in the liquid fuel lines or liquid containing compartments of the carburetor during warm weather operation.

Fuel under pressure flows through line 25 and line 26 to enter compartment I8 and when filled no furtherow of fuel through line 26 occurs since there is no opening or outlet to chamber I8 other than said line 26. Fuel for carbureton from line 25 passes on through line 21 through needle valve 29 and into the liquid feed chamber I9. When the engine is not operating, the tension spring I I has been so previously adjusted by adjuster I3 that the valve 24 is seated permitting no flow or leakage of liquid from said feed chamber I9 into chamber 20. When the engine is turned for starting purposes a slight vacuum'is created by the passage of air through theventuri 2 which vacuum is communicated through tube 4 and into vacuum chamber 'I. This slight vacuum` or reduction in pressure tends to pull diaphragm 8 downward since the upper surface of said diaphragm and chamber 9 are open to atmospheric pressure or pressure ahead of venturi. This very slight downward movement of diaphragm 8 opens valve 24 permitting flow of liquid fuel from liquid feed chamber I9 into chamber 20. The partial vacuum communicated through line 4 into compartment 1 is also communicated through line 5 and tube 28 into'chamber 20. 'I'his slight vacuum together with the vaporizing tendency of the high vapor pressure fuel very quickly feeds hydrocarbon vapors through line 5 into the intake air current thereby forming a combustible gas mixture for passage through the intake manifoldand into the cylinders. Obviously, as soon as a cylinder fires, the engine is turned over rapidly thereby creating a greater flow of air through the intake I and greatly magnifying the pressure differential on the diaphragm 8 and further opening valve 24. Where fuels of relatively low vapor pressure or two phase fuels having a normally liquid phase are employed, partial vaporization on pressure drop through valve 24 will entrain normally liquid constituents maintaining chamber 29 and tube 28 practically free of liquid.

As mentioned above, when the engine is not in operation, the liquid pressures in liquid feed chamber I9 and liquid pressure chamber I8 are equal. chamber I9 into chamber 20, the liquid pressure infsaid liquid feed chamber I9 decreases, dependent upon degree of opening and rate of flow through valve 24 and the setting of valve 29 which produces a pressure dierential between chambers I8 and I9. The decrease in pressure on the upper side of liquid operated diaphragm I I causes said diaphragm to raise upward tending to offset the downward push from the diaphragm 8 and to close fuel valve 24. The surface areas or more specifically the sizes of these diaphragme are so chosen that an equilibrium is established between the downward tendency of diaphragm 8 and the upward tendency of diaphragm I'I so that the amount of opening of the valve 24 is a function of the amount of suction created Withinl'the Venr ,and air for idling of the motor from chamber 20.

The amount of fuel entering the motor intake for idling is controlled by manual adjustment or setting of the needle valve 30 in line 3l.

Valve 24 and valve seat 23 should beof very small diameter since the amount of liquid fuel passing through this opening is very small. For example, a horse-power engine uses a maximum of only about 0.6 cubic inch of liquidv fuel per second, and the valve surface by being small may be easily opened even though it is opened against the pressure within the liquid fuel chamber. This arrangement permits the valve 24 to be quite sensitive to suction variations in vacuum chamber 'I and, therefore, responsive to the operation of throttle 3.

A more efficient design of my carburetor for making the same sensitive and responsive to load requirements requires that vacuum chamber I be made of as small volume as possible. The smaller the volume of chamber 1, the less is th'e lag of diaphragm 8 in response to vacuum changes in vacuum tube 4. In addition a better design pointing to utility is the size lor clearance of push pin bearing or guide I6, which should be made as small as possible and yet allow free movement of push pin I5 to prevent leakage of vapor or liquid into chamber I from chamber 20.

Line 21, as seen in thegure, conducts liquid fuel through cooling zone 28 enroute to liquid feed chamber I9. 'I'his cooling is for the purpose of preventing premature vaporization or vapor lock by reduction of pressure on passage through the jet or adjustable valve 29. Partial vaporization of the liquid fuel in chamber 20 When valve 24 opens, liquid flows from serve as a guide: Assume diaphragm 8 has an area of 60 square inchesand diaphragm I1 has an area of 10 square inches. The air flow through venturi 2 at three-fourths motor load may produce a suction or vacuum of 25 inches of water column through suction tube 4, the pressure on the underside of said diaphragm 8 will be reduced to 25 inches of Water column less than the pressure in air chamber 9, and the total downward forceexerted on diaphragm 8 is 25 inches water cohunnXO square inches However, when the flow of liquid begins, the

pressure in chamber I9 becomes less than pressure in chamber I8 due to the pressure drop through needle valve 29. This valve is so set as to obtain the correct mixture and for the above assumed conditions, it would be set so that the a,

correct amount of fuel for three-fourths engine load would give 150 inches water pressure drop across said valve 29. This pressure drop is required as 150 inches water differential acting on diaphragm II will produce a force of 150 inches WaterX l0 square inches 27.7

This 53 pound force acting upward on diaphragm I1 is transmitted to push pin I5 and exactly counterbalances the downward force from the diaphragm 8, thereby holding valve 24 in a position that will permit the liquid fuel flow to be such an amount as will give a pressure drop of 150 inches of water across valve 29. If the mixture flow is reduced by throttle 3 so that the suction produced by venturi 2 is only 5 inches water pressure, the force on push pin I5 will be (x60) /27.1=10.6 pounds, i and valve 24 will then close until the pressure drop across needle valve 29 is only 30 inches water pressure which will give an upward force on diaphragm I1 of (30x10) /2'I.'I=10.6 pounds to balance the downward force from diaphragm 8. Thus, reduction of air flow to change the Venturi suction from 25V inches water pressure to 5 inches water pressure will reduce the quantityof air in the same proportions that a change from 1,50 inches to 30 inches of water pressure drop across valve 29 changes the fuel flow. 4

In case an air cleaner is used, vent I0 should preferablyvbe connected to the carburetor air inlet on the down streani side from the air =53 pounds 53 poundsl cleaner ihn order to balance the air cleaner friction. Y

While the one embodiment of my invention, as represented by the drawing and fully described in the specications, is a satisfactory and'useful design, I do not wish to be limited to this one design. Many of the component parts may be altered as to size and shape and yet remain within the intended scope of my invention. Under certain conditions, one or two component parts may be entirelyornitted, as heretofore explained, and my invention still serves its useful purpose, or it may even be more eilicient and sensitive in its operation than the above described embodiment,

I claim:

In an internal combustion engine fuel supply system for utilizing hydrocarbon fuels, certain components of which possess a superatmospheric vapor pressure, an air inlet tube, a main throttle valve in the tube, a liquid fuel conduit, a vaporization chamber wherein, on pressure reduction, vaporization accompanied by cooling of the high pressure components of said fuel takes place and a vapor tube delivering fuel from said chamber to the air inlet tube. means for regulating the supply of fuel relative to air comprising a main liquid-fuel chamber connected with the liquid fuel conduit, a second liquid fuel chamber connected with the liquid fuel conduit, said liquid fuel chambers being separated by a fuel diaphragm, a valve for controlling the flow of fuel from the main liquid fuel chamber to the vaporization chamber and reducing the pressure of said fuel, anV air chamber communicating with the atmosphere, a second air chamber communieating with said air inlet tube, said air chambers being separated by an air diaphragm, force transmitting means connected with said air and fuel diaphragms and said fuel valve, a restriction in said liquid fuel conduit for establishing a pressure diierential across the fuel diaphragm vtending to reduce the degree of valve opening on increase in fuel flow through the conduit, a portion of said liquid fue] conduit upstream of said restriction being located within said vapor tube in heat exchange relationship with the vaporized high pressure components of 'said hydrocarbon fuel, means In the air inlet tube on the inlet side of said main throttle valve producing a pressure differential on said air diaphragm tending to increase the degree of opening'of said fuel valve on increase of air flow through the air inlet tube. a tube connected with thevaporlzation chamber and communicating with the air inlet tube on the engine side of laid main throttle valve for utilizing high pressure components of said hydrocarbon fuel during idling and a spring normally tending to hold said fuel valve closed but so adjusted as to allow the fuel valve to remain open during idling.

OWEN L. GARRETSON.

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