US1781276A - Carburetor - Google Patents

Description

Nov. 11, 1930. L. R. EBERT 1,781,276

CARBURETOR Filed Feb. 15, 1924 0 0 N m K} a k} w m4 f) 4*; Pi m g I ,R 1; w a "3 IN VEN TOR v Laurence R Eberl,

A TTORNE YS Patented Nov. 11, 1930 UNITED STATES PATENT OFFICE CARBURETOB Application filed February 13, 1924. Serial No. 692,567.

This invention relates to carburetors and has for its object the providing of a device for supplying an economical combustible mixture to an internal combustion engine.

Another object is the providing of a carburetor, wherein the fuel or float chamber is under reduced pressure, caused by the intake suction of an internal combustion engine, and thus is capable of drawing 1 liquid fuel therein when situated higher than its fuel supply under atmospheric pressure.

A further object of this invention is the provision of a means for controlling and proportioning a liquidfuel supply within a carburetor through the control of the velocity and kinetic energy of air within an air passage or duct.

A still further object of this invention 29 is to provide a carburetor which will ato mize a liquid fuel to a very finely divided state, and thus to realize the advantages obtained of greater inflammability and uniformity of delivery to the cylinders of an internal combustion engine.

Another object of this invention is to provide a carburetor which at all times will deliver, within the limits of combustibility, a maximum amount of air and fuel mixture to the cylinders of an internal combustion engine thus keeping the compression therein as great as possible, which increases efficiency of operation of the engine; such a mixture at all times to be proportioned in fuelfcontent to the. power demands of the engine.

This invention will be best understood from, a consideration of the following detailed description, in view of the accompanying drawing forming a part of the specification; nevertheless it is to be understood that the invention is not confined to the disclosure, being susceptible of such changes and modifications which shall offer no material departure from the salient features of the invention as expressed in the appended claims.

In the drawings Figural is a View in elevation of the carburetor constructed according to my principles. i

Fig. 2 is a view in elevation and partly in section of the carburetor shown in Fig. 1.

Fig. 3 is a section of one of the screens through which the fuel and air is passed.

Fig. 4: is a horizontal section of the mixing nozzle and shows the position of the fuel. jets connecting the fuel chamber with the interior of the mixing nozzle.

Referring more particularly to the drawings, 1 designates the body of the carburetor, being a hollow cylinder in form and suitably attached to a casting 26 at its upper end and to a casting 3, Fig. 2, at its lower end, the method of connection being shown by means of threads but it will be noted that any well known form, such as lateral flanges, may be employed for boltin the sections of the carburetor together. it is thus seen that casing 1, Figs. 1 and 2, cylindrical in form, with attached casting 26 at the top and cast ing 3 at the bottom forms a closed container, except for an air inlet through nozzle 16, Fig. 2; at the bottom and an outlet through an orifice at 27, Fig. 2, at the top. The suction produced by an internal combustion engine causes air to flow through this container in the usual manner. The amount, and reduc tion of pressure, therein, is controlled, as hereinafter described by the opening of a valve25, Fig. 2, placed near the upper end of andwithin angled duct 22-23, Figs. 1 and 2, which duct terminates in nozzle 16, Fig. 2. The container consisting of members 2613, Figs. 1 and 2, is therefore under an equilibrium of reduced pressure, except as modified by the kinetics of the air passing therethrough. The reduction of pressure in casing 3, Fig. 2, will allow fuel to flow thereinto against the force of gravity from some supply under atmospheric pressure as a fuel tank situated at a lower level. This advan tage is utilized by placing within casing 3, Fig. 2, float 5 and valve 8, which control the fuel height therein in the usual manner. Float 5, *ig. 2, is pivotally connected to lever 6, fulcrumed at 7 and terminating in a slot of valve 8, which opens and closes on seat 11 of fuel passage 12 with the rise and fall of float 5. Valve 8 is a cylindrical rod which passes through a hole at 10, turned to a guide fit and terminates at 9 on the exterior of cas ing 3. This is for the purpose of sub- -jecting its upper end to a downward atmospheric pressure, thus overcoming the tendencyvof the valve to lift due to the unbal-' anced pressure on the interior and exterior of seat 11. It will be noted that 9 and 10,.Fig. 2, do not make an hermetically sealed joint, but that this has no effect on the reduction of pressure in casting 3 except to make it generally slightly less throughout the whole container, consisting as before mentioned of members 2613, as any other air leak 1nlet situated at anyother place would do.,

However, as modified by the kinetics of the air stream through the container, the pressure in float chamber 3 is slightly less than in nozzle 16, Fig. 2. This will be later describedin detail.. Nozzle 16, Figs. 2 and 1 is of novel use and construction in a carburetor of the character described as it causes fuel to flow from the float chamber 3 into its interior although the relativepressures may he as previously mentioned, and will now be more minutely described. Nozzle 16 is more or less cylindrical in form which with duct 22 forms a continuous air passage making a leakless joint through the bottom of casing 3. Fuel ducts 21,'Figs. 2 and 4:, beginning on the exterior of nozzle .16 below the fuel level in float chamber3, Fig. 2, lead upwardly and radially inwardly and terminate in flat surfaces 21., shown in cross section inFi'g. 2, and in top view in Fig. 1, in the interior of nozzle16, and in a plane situated above the fuel level in float chamber 3, and perpendicular to the axis of nozzle 16. The ascending air stream in nozzle 16 is cleft or parted by the projection of ducts or passages 21 therein, and this congestion produces a local reduction of pressure or partial vacuum upon and above flat surfaces 21. This is less than the pressure in float chamber 3, and thus the liquid fuel is caused to flow through the fuel passages 21, Lon'to flat surfaces 21, or by momentum carried beyondthem, where it mingles with the ascending air current and thus is carried up,- ward with it. That such a reduction of air pressure does exist may be illustrated and proven in thefollowing manner. The portion of the air stream cleft or displaced by fuel passages or ducts 21 projecting in nozzle 16 deflects back to resume its normal course again above fiat surfaces 21*. This deflection isva change invelocity. The definition forhvelocity is directed speed. Now quoting what has been called Sir Isaac Newtons third law of motion: change in velocity is directly proportional to the force acting and takes direction in which the force acts, we see that it not only shows but quantitatively measures some force at 21 causing this: deflection. This can only bedue to a reduction of pressure. It is further pointed out that the principle of using the velocity of the passing fluid to produce a negative pressure head, as is done here in my invention, is not entirely new in mechanics, but is a novel use in con nection with carburetors. It is used in the priming of the steam engine injector, in the steam and air jets for raising water, in the filter pump used in chemistry, and in many induced drafts and steam blowers. In order that this deflection above referred to may be unhampered at the faces 21 they are made flat surfaces at right angles to the air current, otherwise with the velocities in use the reduction of pressure would be too feeble to be of practical benefit. Nozzle 16 is not considered a proportioner of air and fuel as such proportioning would be too complicated and while the carburetor was adjusting itselfto a change in capacity, demanding an acceleration of fuel; and air quantity, the air would accelerate faster than the fuel as the force acting upon the air is the full reduction in pressure from atmospheric, while that actingupon the heavier and more sluggish fuel is the small difference in pressure between that in float chamber 3 and the local reduction on flat surfaces 21*. Fuel would therefore lag behind the air in phase during this change and proportions reaching the engine would be faulty. Nozzle 16 functions therefore mere ly to supply an excess of fuel at all times. This obviates any adjustment or control of a fine and delicate fueljet, which fact is considered a novel and manifest advantage in-the construction of a carburetor. It will be seen fromthe foregoing description that fuel sprayed into mixing chamber 1, Figs. 1 and 2, must return, if not'used, to float chamber 3, Fig. 2. Thus used in connection with nozzle 16, and further assisted by the structure of casing 1, float chamber 3'serves as a return trap for excess fuel. The correlation is thus furtherexplained. Casing 1, Figs. 1 and 2, and its internal structureis termed the mixing chamber. The latter consists of a series ofpartly spherical fine wire screens or gauze 5051, Figs. 2 and 3, convexed up? wardly and progressively increasing in diameter upwardly. The portion illustrated in F 2 may be termed similarto the right section of an inverted cone. I These wire screens 5051 are mounted at their periph-v eries on convexed discs 2049, Figs. 2'and 3,

which fit loosely within casing, 1, Fig. 2. Distance rings 19, F igs. 2 and 3, indented at their lowerends as at 52, Fig. 3, suitably space and'support the screens and discs. Screens "50-51, discs 2049', and rings 19 form a structure with many small openings sloping downwardly and outwardly from the air cur rent, thus assisting and allowing excess fuel to run outwardly to the outer peripheries of discs 49, where the fuel coacts against the inner side of easing 1 causing the excess fuel to flow back through said openings to float chamber 3, Fig. 2. The particular structure of the screens, discs and rings together with casing 1 all work together to permit the excess fuel to find its way back by gravity to float chamber 3, Fig. 2, seeping as it were off the conveXed screens and discs and between them and the inside of casing 1 downward to its former source tobe used over again. The whole structure is supported by ring 19, resting on a flanged portion 18 of nozzle 16, Fig. 2. It will be noted that ring 19 and supporting flange 18 are sufiiciently bored or punctured to allow the free passage of air between mixing chamber 1 and float chamber 3 as well as into the interior of this conical structure. Float chamber 3 also has free air communication with the exhaust of nozzle 16 which has a slightly less pressure than the lower portions of nozzle 16, and the pressure in float chamber 3 may be further reduced by a suction induced by the ascending air above this portion of the structure. Thus the pressure may be less in float chamber 3 than in nozzle 16, notwithstanding the small leak of air between 9 and 10, Fig. 2, as heretofore described.

The dynamics of the ascending conical air current through the screen structure 51 possesses these properties. Its force of impact, or the thickness of a quantity of fuel it is capable of holding in equilibrium of suspension therein varies as the square of the velocity. The kinetic energy passing any given area or available thereupon is the product of the mass times the square of the velocity. Mass being directly proportional to velocity, the kinetic energy available upon any unit area varies as thecube of the velocity. Both of the properties are rapidly decreasing functions as the air velocity decreases or the channel becomes larger. The former limits the size of particles that may be moved upwardly while the latter available in supplying the work quantities in overcoming the several resistances encountered in passing the fuel upward. and through the screens limits the final quantity of fuel delivered. These properties are realized in the screen structure 5051 of the carburetor as follows: Fuel in excess quantities as supplied by nozzle 16 becomes heaped up on the lower screens, where it is a seething mass in a con- 7 air.

'stant state of eruption as the channel becomes choked and broken through by the ascending Atthe same time fuel is flowing outwardly and finds its way back to float chamher 3 as described. Progressively upwardly a less quantity of fuel, as determined by the previous return or runoff to float chamher 3, is supplied to a progressively greater screen area. The effect of the air from the constricted nozzle 16 becomes less, and the fuel has a tendency to spread outupon the screens 50-51, especially the upper ones until a thickness at which it will be held in equilibrium of suspension by the force of the ascending air is reached. Progressively upward it forms a thinner coating upon screens 5051, its inertia becomes less, its peculiar sensitiveness to change in air velocity more marked, and smaller quantities are carried upward. The final result is that the fuel is spread so finely upon the upper screens, and is so minutely and instantly sensitive to a change in air velocity that the choking effect upon the air column has practically disappeared. Here in this part of the carburetor the functioning of the air current as heretofore described as a square and a cube function of its velocity takes place. The final result is the delivery through the upper screen 51, Fig. 2, of an air and liquid fuel mixture, the latter atomized to the consistency of a fog. My invention illustrates and shows the difference between this screen structure acting as an atomizer and one used merely to atomize fuel by the successive division of it in its passage through screens 5051, Fig. 2. The latter has no ability to proportion air and fuel. Any division of the fuel causes a retardation of its velocity. During a change in capacity of such a structure the fuel will lag behind the air supply, delivering a faulty proportioning to the engine, or

should the air supply be retarded as is the fuel, it will re-accelerate faster and thus leave the fuel behind. It is only by having these fine fuel coatings peculiarly responsive and almost instantly sensitive to changes in air' volume and immediately replaceable that this difficulty is overcome by my invention.

Regulated valve 25 in conjunction with air passages 23-22, Fig. 2, by the dynamics of the air alone supplies the initial fuel quantity and regulates the final output of mixing chamber 3. This is considered of novel use in this respect and possesses the advantage of a larger volume, easier to control, and less delicate in its adjustments than the finer fuel jets commonly heretofore employed in other carburetors for proportioning fuel content. It will be noted that the fuel quantity regulated by the air kinetics is not directly proportional to the air supplied, but that it vai ries as some power of it, which as has been indlcated is very nearly a square fllIlClllOll. As this is an improper proportioning of air and fuel further regulation is necessary, and this is done as heretofore described by and through the remaining parts of the carburetor.

A horizontal cylindrical air duct 26, Fig. 2, is provided, which terminates in a three walled horizontal trough 28, which with its '1 cover or cap 30, Figs. 1 and 2, is rectangular or trapezoidal in cross section. Cover 30 is appropriately fastened to the side Walls of the trough by bolts or screws 31, Fig. 1. Passing through the bottom wall of the trough and sit iii) aid

uated on the exhaust side of regulated valve 36 is an orifice at 27 Fig. 2, which carries the mixtureproduced by the proportioning of the air and fuel, as described in mixing chamher 1 into trough 28. Trough 28 terminates in a cylindricalpassage 29 which contains throttlevalve 32 mounted and functioning in the usual manner. ,An appropriate flange 35 serves to connect the carburetor as awhole, to the intake of an lnternal combustion enoine. ic e n u Valve 36, F 1g. 2, controls the dilution air supply into duct 28, by opening and closing the passage at 36*, Fig. 2. Valve 36 is rigidly connected to shaft 3'? and oscillates with it. Shaft 37 bears throughout its interior upper portion in cover 30, Fig. 2, and extends through the side walls of trough 28 beyond the exterior of the carburetor structure. Lever arm 38, Fig.1, is rigidly attached to shaft 37and depends therefrom. Collar 46,

Fig. 1, is adjustable for position on lever arm 38, and is pivotally connected to an end of a lungs or knuckle 3o1nt, consist ng of elon gated links 4:1 and 42, and their pm connections 43, Fig. 1. The opposite end of the hinge 1. This resistance to opening produces th desired suction or. reduction of pressure in the carburetor posterior to these two valves. Some flexible means illustrated as a. chain 44, Fig. 1,-is attached to the middle of the hinge joint at pin connection 43, Fig. 1. By raising or lowering ofchain all from some distant point, the hinge joint may be closed or opened thus giving to valve25 a controlled initial opening. The kinematics of therelati-on of the motions or openings of these two valves is. complicated and discussion thereof would be out of place here. The controlling factors are, however, the angle at which valve 36 is placed in trough 28, Fig. 2; the angle or succession of angles of intersection of the axes ofthe two pend'antlevers 38 and a0, Fig. l;

the point from which chain member- 44 swings; (it will be seen. in drawing Fig. 1,

that chain i l as there positioned will cause the hinge joint to close slightly as thevalves open, thus giving to valve 25 a relatively greater motion) and the two movable adjustments of collar and chain as heretofore mentioned. The former may be so fixed or proportioned that with the aid of the two movable adjustments of collar and chain, any desired proportioning of. the final air and fuel content throughout the capacity of the carburetormaybe attained, and th'ismay be weal-:- ened or strengthened at will by any mechanism which conveniently. operates through chain 44: the closing or opening of the hinge joint. In actual operationit has been found an ideal proportioning especially economical for use in motor driven vehicles; starts from a richer mixture at idling speed and demand, thence weakens down in fuel content to meet the demands of the lower travelling speeds, thus allowing a maximum quantity of a minimum leanness of fuel and air mixture as practicable; thence increasing in fuel content or power'withincreased speed or power demand by the vehicle, but still functioning at the'leanest possible mixture that Wlll'ill'lswer the power output. -At maximum capacityxth s would become a mixture of maximum power. Heretofore this ideal combination lias not been'realiz ed, because in passing from alower demand to a higher one the tendency during this passage is for the fuel to lag behind the air, as has been indicated, and during th s period the mixture would become still further thinned in fuel content,

such that itmight not support combustion or at least would'laclr at best power to produce acceleratlon. These difliculties have been obviated in the type of construction employed which will now be further explained.

. Throttle valve 32, Fig. 2, as its name implies controls the amount of combustible mixture to the engine by throttling it. Hence the pressure on the exhaust side is less than on the intake. Anadditional opening of throttle valve 32 reduces thepressure or increases the suction within the carburetor structure. The valves with their connecting mechanism possessing cons derable inertia are not immediately responsive to this reduced pressure, and they lag behind their position of equilibrium andthis continues so long as theenglne is accelerating. Fora diiferential change in reduction of pressure it may be assumed that the differential change in valve I openings has not yet occurred. The quantity of air flowing varies as the square root of the reduction pressure. The fine fuel films or coatings on the screens 50 to 51', Fig. 2, in' equilibrium of suspension and practically inertialess incorporate themselves with the ascending air in a ratio proportioned to tl e square of the velocityof said ascending air current, or directly proportional to the reductron 1n pressure of said air .current' Hence the difierential fuel quantity is greater than the corresponding differential air quantity,

and the mixture thus becomes strengthened powerful combustible nnxture is thus supplied'to the engine for acceleration purposes.

in fuel content.

VVhen the engine is laboring s'lowlyunder a full load, at such times the throttle Valve is wide open, but the 7 carburetor working under small capacity and would ordinarily deliver a weak powerless mixture. The pulsations in the engines intake are communicated to the mixing chamber 3 where they augment the output of fuel from the fine fuel coatings, but have little or no effect on the more sluggish valves 25 and 36, Fig. 2. Under these conditions the desired powerfully combustible mixture is automatically furnished to the engine. The primary and the dilution air supplies are given a common intake; that is through duct or cylinder 26, Fig. 2. This has for its purpose the furnishing of an air supply from a common source as through 48, Fig. 1. Preheated air may thus be fed to the carburetor, which is now the general practice. This is of particular advantage in a carburetor of this type, where a more volatile fuel is to be evaporated, as the fuel on the screen structure presents a large surface for evaporation, and it is exposed to the air a relatively long time.

.A rise in temperature increases the inflammability of an air and fuel mixture and may cause a mixture too thin in fuel content to support combustion at a lower temperature, to become a combustible one at a higher temperature. This again is of particular advantage in a carburetor of the construction being described, which is designed to handle fuel mixtures of a minimum of fuel content,

as heretofore explained.

While there has been shown and described in considerable detail the specific embodiment of my invention, it is to be understood that this is illustrative only, and that I do not regard the invention as limited to these details, nor'to any of them, except in so far as such limitations are included within the terms of the accompanying claims in which it is my intention to claim all of the novelty inherent in my invention as broadly as is permissible in view of the prior art.

What I claim is:

1. A carburetor comprising a primary air conduit providing for an air supply, a fuel chamber, a fuel nozzle for directly supplying the primary air with fuel, duets with upper ends flat, opening into said fuel nozzle, a secondary air conduit for supplying air to the combustible mixture for diluting said mixture, a valve in the primary air conduit, a valve in thersecondary air conduit, means for connecting said valves, means for actuating the valve in the primary air conduit, said connecting means between the valves permitting independent actuation of the valve in the secondary conduit.

2. A carburetor comprising a primary air conduit providing for an air supply, a fuel chamber, a fuel nozzle for directly supplying the primary air with fuel, duets with upper ends flat, opening into said fuel nozzle, a secondary air conduit for supplying air to the combustible mixture for diluting said mixture, a valve in the primary air conduit, a valve in the secondary air conduit, means for connecting said valves, means for actuating the valve in the primary air conduit, said connecting means between the valves permitting independent actuation of the valve in the secondary air conduit, and means adapted to vary the points of connection between the valves for varying the relation of the operation of said valves.

3. A carburetor comprising a mixing chamber, a float chamber, a primary and a secondary air intake passage, a lever controlled valve within each air intake passage, connecting means for the simultaneous operation of said valves to control the flow of air through said two air intake passages, a shaft forming one extremity of said intake valve, a pendant lever attached to said shaft, a collar attached to each of said levers, a hinge joint consisting of two link members pivotally attached together and supported by a flexible member capable of manual operation, one end of said hinge joint being pivotally attached to the collar on the primary air intake valve lever, the opposite end being similarly connected to the collar on said other pendant lever, and appropriate spring means for holding said valves in their closed position and offering resistance to their opening, substantially as and for the purposes described.

LAURENCE RUDOLPH EBERT.

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