US2020141A - Carburetor - Google Patents

Description

Patented Nov. 5, 1935 Ul'l' PATENT OFFICE Claims.

Unless due cognizance be taken of the inherent defects and obstacles to be overcome in the construction of. all carburetors, even a detailed description thereof would not adequately fulfill the spirit or intent of the patent law; therefore some of these defects will be briefly stated in order that my objects, constructions, and claims may be better understood.

1. The methods applied in a process of carburetion should offer as little resistance as possible to the free flow of gases through the carburetor, because any restriction to free flow lessens the quantitative delivery to the engine.

2. A high velocity contact of the air upon the fuel jets is necessary to atomize the fuel finely and assure evenness of carburetion. Item 2 thus is opposed to item 1", as a high velocity of fio-w must necessarily be through a restricted passage.

3. The flow of fluid within and through carburetor and engine intake passages is not uniformly continuous, for this flow becomes suddenly stopped in velocity and path by the closure of an intake valve, to be redirected in velocity and path by the opening of another. The frequency of this may be high enough to form sound waves, in addition to which, pulsations, eddies, and a phenomenon very analogous to an elastic water hammer are generated. This heterogeneous combination of vibrations, pulsations, etc., I term for Want of a better name surge. This surge reacts upon the liquid fuel flow differently than upon the air, sometimes rendering the carburetor valueless. High air velocity in the neighborhood of the fuel jets may deaden this surge. Hence item 3 also is opposed to item 1.

4. The application of a motive force, such as the suction supplied by an internal combustion engine to a carburetor, upon two fluids of different densities, as air and liquid fuel, will cause the lighter to react to this force more sensitively and quickly than the heavier. Acceleration of. the air velocity within a carburetor is greatly more rapid than the liquid fuel which results in the air 1eav-' ing behind the fuel particularly upon acceleration, or air and fuel do not remain in phase. This effect has a tendency to weaken the carbureted mixture in fuel content at the cylinders of an internal combustion engine during its acceleration. The net result is that power for accelerating purposes is lacking, or the mixture may be too weak in fuel content to combust.

Preliminary to a disclosure of my invention it is desirable tomake a note of two varieties of currents:

1. Primary currents, which are caused to flow due to a difference in terminal pressures, and 2, secondary or induced currents, caused by the dynamic action of some primary current acting upon them. Such a flow may be largely inde- 5 pendent of initial and terminal pressures as witness the steam engine injector, wherein water is induced to flow from atmospheric pressure into a boiler against that pressure. The secondary currents generally are small in comparison with their primaries and their velocity or quantity of flow is not directly proportional to the velocity of flow of the primary, but more nearly as the square thereof.

One object of. my invention is to provide a large, and unrestricted primary air passage within a carburetor, for the purpose of giving to an internal combustion engine high speed and power at that speed.

Another object of my invention provides for a secondary air duct, in which the flow of air there through is partially induced by a primary passage.

A further object of my invention provides for atomizing a liquid fuel very finely by causing it to discharge in a very thin sheet or film, into contact with an air current.

A further object of my invention consists in the provision of a device, for compensating for the lack of fuel content in a carbureted mixture, during acceleration in quantity of said mixture.

A further object of my invention includes a means for quickly changing the ratio of fuel to air content of a carbureted mixture, said change or control to be effected from some remote point. Roughly speaking this is equivalent to adjusting the carburetor.

Other objects and novel features will be hereinafter explained in detail in the accompanying drawing, the subjoined specification and the appended claims.

It is understood that various modifications may be made in the details of construction and design of the various parts hereafter described and claimed without departing from the scope and spirit of the invention.

In the drawing, wherein like numbers refer to corresponding parts in the several views:

Figure 1 is a side view inelevation of the carburetor.

Figure 2 is a sectional view of Figure 1.

Figure 3 is a sectional view of a part, termed the accelerator.

Figure 4 is a view looking down upon the top of the cover plate of the carburetors fuel chamber, sectioned to show details of fuel passages.

Figure 5 is a sectional view on the line 5-5 of Figure 1, showing details of fuel passages and metering valves.

Number Figs. 1 and 2, is the carburetor head, shown flanged at 2, and drilled with holes at 3 for bolting onto an intake manifold of an internal combustion engine. At in Fig. 2 is shown the throttle valve attached to its shaft 8 by being passed therethrough. Shaft 8 is passed without the shell, and upon its outer end is attached throttle lever 9, Fig. 1. Throttle valve 1 is opened or closed by oscillation with shaft 8 and lever 9 in the conventional manner. The upper portion of head I is supported by legs 4-4, Fig. 1, above a circular flange 5, Figs. 1 and 2, forming the lower extremity of head I. The open spaces at 6, Fig. 1, form the air inlets into the primary air passage within the hollow interior of head I, Figs. 1 and 2. Within the interior of head I, and movable up and down therein, is a Venturi-like member |,Figs. 1 and 2, shown in these views in its uppermost or normal position. Reference is now made to Fig. l. A pin I5 is rigidly fastened to Venturi passes through the shell of head through a slot at l6. Pivotally attached to pin I5 is lever arm l3, which is rigidly attached to shaft l4 which oscillates in a bracket |2 forming part of member I, Figs. 1 and 2. A pin i9 is attached to the other end of lever l3. Said pin passes through a slot at I8 in member IT. A coil spring 29 to be described later tends to hold Venturi II in its upper position and pin IS in the lower end of the slot at |8 as shown in Fig. 1. Member may be extended to some remote point, where if moved in the direction as shown by the arrow, it will coact with pin l9, lever I3 and pin IE to depress Venturi member ll, thus closing the passages at 6 to any amount desired. This meters the flow of air through these inlets at 6 and controls at will the proportions of fuel to air in the final carbureted mixture. Although carburetion has not yet been described, it is here stated that one function of the primary air current is to dilute a previously prepared mixture, the disclosure of which will follow. Reference is now being made to Figures 1 and 3. The Venturi pin I5 is further straddled by a forked or flanged upper portion 28-28 of hollow cylinder 2|. A guide 22 passes through cover plate 23 of a conventional fuel chamber 25, and provides an entrance for cylinder 2| into a recessed portion 24 of float chamber 25, wherein the lower portion of said cylinder is immersed below the fuel level as shown in Fig. 3. At 26 is shown a small fuel duct communicating between float chamber 25 and the hollow interior at 21 of sylinder 2|. Circumscribing cylinder 2| between guide 22 and lower flanged portion 28 is a helical spring 29, which by pressing upwardly on flange 28 tends 'to hold cylinder 2| in its upward position, and acting through pin |5 as heretofore described the Venturi H and connections are normally held in their uppermost or open position. A plunger 20 fits movably into cylinder 2|. A slow downward movement of this plunger will force fuel out through passage at 26 and plunger 20 will sink within cylinder 2|. A quicker movement of plunger 20 will only partially allow the fuel to escape through the restricted passage and cylinder 2| will follow the plunger down more or less during the operation. This downward movement of cylinder 2| coacting through Venturi pin l5 will cause a corresponding movement of Venturi II and its levered connections. Spring 29 will then react to bring cylinder 2 i, Venturi and lever connections back to the normal or open position. Plunger 20 is caused to move downwardly by contacting with cam |D, here shown as a part 5 of throttle lever 9, hence the velocity and amplitude of throttle valve opening is correspondingly transmitted to plunger 20 and through the mechanism described the required depression of the Venturi. Having thus depressed my ven- 10 turi and thereby correspondingly closed the spaces at 6 as heretofore explained, there is correlated the regulation of my primary air passage with the acceleration in capacity of the carburetor, for quick opening of the throttle 15 valve and amplitude of opening also is a measure of the accelerated capacity of the carburetor. As has been pointed out heretofore quick acceleration will effect air flow first, causing engine cylinders and manifolds to contain an ex- 20 cess of air, and one logical method would be to retard the flow of this air during the operation, as is done by depressing venturi H, and closing main air inlets at 6. This is a very important feature and an advantage as it gives 25 power to an automotive engine to accelerate the speed of the car. The majority of carburetors offset the tendency to run on-a powerless mixture during acceleration, by normally running on a mixture too rich in fuel content, for best economy and operation. No such compromise is necessary when such an acceleration as described for my invention is used. When an internal combustion engine is operating at low load or at a fraction of its full capacity, the carbureted mixture fed thereto is a corresponding fraction of the full load quantity. As this charge is compressed into a certain volume within the compression or clearance space of the cylinders it will attain only a fractional part of the full ca- 9 pacity compression pressure. When this same underload power may be obtained with a less powerful mixture, such as one containing a smaller proportion of fuel would be, it will require a greater quantity thereof, and the compression pressure will becorrespondingly greater. The added economy of operating under a higher compression pressure more than offsets the lack of economy in the use of the weaker or more inefficient mixture, so that the net result is an in- 50 crease in efficiency and economy of operation.

The use of my primary air passage in combination with the accelerator enables it to operate on the less powerful mixture, and automatically increases the power for accelerating purposes. The 55 manual adjustment of the venturis position in the primary air passages enables a quick change from a powerless to a very powerful mixture, when power and speed are required.

Having described the primary air passage the 0 secondary passage will be described. It is also an air and fuel mixing passage. This passage is best illustrated in section in Fig. 2, and is indicated by the number 4|. It is formed by the fastening of nozzle plate 38 and float chamber 5 cover 23, and is constructed to form a narrow throat M Figs. 2 and 4, located at the junction of these two plates. Above this narrow throat at M the passage flares out as an inverted conical nozzle, and terminates just within the lower ex- 70 tremity of the hollow Venturi member H, where it is capped by a screen of fine mesh. 59. Below the throat at 4| it widens out into a cylindrical passage, formed through a downward extension- 40 of cover plate 23. Said extension 40 passes 16 metered and passaged to a fuel supply, is formed by recessing the two plates 38 and 23, Figs. 2 and 4, as illustrated. The walls of this reservoir converge inwardly until at 43, Figs. 2 and 4, they form a passage between them a few thousandths of an inch in thickness. The walls then diverge slightly from there to the throat at 4i of the air passage formed by member 40. Fuel is thus caused to flow in the form of a very thin sheet into the restricted throat at 4| a where the air velocity is the highest within passage 4 I. This construction serves to atomize the fuel very finely. These fuel particles are further broken up upon passing through screen 59, Fig. 2. Screen 59 also partially baffles any air surge downwardly directed upon it, and thus minimizes the effect of this surge within the. secondary, or air and fuel mixing passage, and the fuel passage connected therewith. Screen 59 also offers a mild obstruction to upward flow of gases in the secondary air passage, and causes a uniform cross-sectional velocity of flow in the upper part of the conical nozzle which it caps. Ordinarily air will flow into the carburetor with equal impartiality through both the primary and the secondary air passages and the highest air velocity attained therein of both will be approximately equal, and will occur at the most constricted part of their respective channels. In the primary passage this constriction is in the neighborhood of the lower extremity of venturi ll, due to space being occupied by the upper nozzle portion of plate 38 projecting therein, Fig. 2. Constriction of channel and position of maximum air velocity in the secondary passage occur at the throat M Fig. 2. Thearea of the secondary air channel at or immediately below screen 59 has been than the throat at M so that the velocity therein is correspondingly less. The mixture discharged from the secondary passage in the primary or main channel at the Venturi base is enpurposely made larger veloped by the mixture in the primary current travelling at a greatly higher velocity. The discharged products of the secondary current quickly diffuse themselves with those of the primary and are carried away with them; more quickly than their tendency to be resupplied. The net result or effect is to create a void, reductionof pressure, or rarification of the gases in the vicinity above screen 59, which is neutralized by an accelerated flowof gases through the secondary passage correspondingly augmenting the supply. This explains the method by which the dynamic action of a primary current may induce the flow of an additional amount of current in a secondary one. The net effect as far as it concerns the construction of my carburetor is, that by this inductive method there is increased the velocity of flow at the throat of the secondary air and fuel passage which serves to better atomize the fuel and combat surge already referred to. Screen 59 coacting with the primary and secondary currents serves another very useful purpose. Particles of fuel which impact with it will be slowed up in their upward velocity and for a time at least will travel more slowly than the sur ber 25. Thus passage 5'! above it is metering needle valve 31*.

avid for fuel vapor. Thus the rapidity of vaporization will be increased. It will be noted that the more rapid primary current will react on the fuel particles of the slower secondary in the same way, and that the screen makes this reaction more violent. Itmay also be noted from an inspection of Fig.2 that the volumetric capacity of the carburetor is afiected very little by the secondary or air and fuel passage. Therefore with my construction a large'resistance may be placed in the secondary without materially affecting the ca-.

paoity of the carburetor. These several resistances to flow are, the constriction of secondary air passage into a narrow throat, the resistance offered by the impact of the air upon the fuel film at throat 4|, Fig. 2, and further resistance to flow offered by screen 59. It is to be noted that had screen 59, Fig. 2, been placed in the main air channel as at the throat of venturi ll, Fig. 2, or any place above this, the resistance to flow therethrough would render the carburetor valueless, for power and high speed purposes. There have been heretofore many attempts to use screens in connection with a carburetor, without considering the resistance they offer to the flow of gases at the high speeds employed, and there are none on the market today using the screen as I do in correlation with the other features of the carburetor, therefore this novel construction and placement are deemed a marked improvement and high order of invention.

Having described the air passages, both primary and secondary, I will now take up the fuel supply and its regulation. A conventional fuel or float chamber is indicated at 25. At 58, Figs. 1-

proper closure of passage 57. A float 53 is placed within chamber forked lever arm member 40, Fig. shown in front of 25, and is pin connected to a which straddles the sectioned 2. The nearer fork which is the sectioned view is indicated by 55, Fig. 2, and its pin connection to the float 53 by number 54. The other extremity is connected to shut off valve 58 to depress the same on the raising of float 53 by the fuel within chamis closed and the supply fuel is shut off in A recessed pocket 41 of in Figs. 1, 2 and 5.

Reference is now had to Figs. 4 and 5. The cover plate 23 is pierced by a hole at 45, Fig. 4, into which member 46, Fig. and positioned within pocket 41. At 48 is shown a fuel passage within member 46 and immediately Fuel passage 48 extends upward and around the stem of said metering needle valve in a passage at 49. Said passage 49 communicates with a passage 44 which extends without member 46' and fits with a passage 44, Fig. 4, formed within cover plate float chamber 25 is shown 5, is tightly fitted 23. Passage 44 discharges more or less tangenof fuel from. this reservoir through restricted orifice at 43 into throat at M Figs. 2 and 4 has been heretofore described. Within 46 is a fuel well 50 generally termed which communicates with atmospheric air above through a restricted passage 5|, and with passage 49 just above passage 48 as shown in Fig. 5. The line A-B Fig. 5, may represent the fuel level within 41 and when the carburetor is at rest it an accelerating well .the carburetor immediately will be the fuel level in reservoir 50 also. When suction is .applied to the fuel passages heretofore described causing the flow of the fuel from reservoir 50 the fuel will flow into passage 49 and the fuel level within said reservoir will be below that in the float chamber, depending upon the suction or reduction of pressure causing fuel flow. Fuel reservoir may entirely empty itself in this manner after which passages 50-5! become an air duct into passage 49. If passage 50-5I were an unrestricted air passage the suction or reduction of pressure upon small passage 48 would be no more than that represented by the height of fuel from A-B to the bottom of the accelerating well 50. However as passage 5| is a limited one the suction upon 48 will increase .after the accelerating well has been emptied, depending on the constriction of flow of passage 5|. The small fuel container 50 has aptly been termed an accelerating well, for upon an increase of suction accompanying an increase or acceleration in carburetor capacity it augments the flow in passage 49 by emptying itself therein, and by this means described increases the fuel content in the carbureted mixture during its action. It has been pointed out that the primary air passage induces an extra flow of the secondary, or air and fuel mixing passages. The secondary passage also acts as an inductor upon the fuel passages, which at the higher capacities will cause an over proportioning of fuel to air in the carbureted'mixture. This is compensated for by the entrance of air into the fuel passages through the acceleration well and the regulation in suction upon the fuel passage 48, Fig. 5, by the size of air passage 5|.

An internal combustion engine will move slowly with no load, or idle as it is termed when the throttle valve is almost or entirely closed. Such a position is shown in Fig. 2. Under such conditions there is not sufficient suction or reduction in pressure to lift the fuel from the float level to the discharge of the fuel passage. In Fig. 5 this lift is approximately represented by the distance between the line A-B and the passage 44. Special means for idling an engine must be employed, generally termed the idling jet or idler. In connection with my carburetor a conventional idling system is used, briefly described as follows: In Fig. 5, metering valve 31 is shown, which is similar in every way to that one described for the main fuel passages, except that there is no accelerating well attached thereto. A metered amount of fuel is thus conducted into a passage at 52, Fig. 4, constructed similarly to passage 44 as described. Passage 52 extends upwardly through cover plate 23 at 33*, as shown in Fig. 4, and joins with a passage 33 extending through nozzle plate 38, Fig. 2, and thereafter contained within the walls of carburetor head I, Fig. 2. Passage 33 is opened at its upper end by two horizontal passages at 3| and 32, Fig. 2, entering above and below the throttle valve respectively. At 34, Figs. 1 and 2, is shown an air bleeder metering valve, seated upon and metering air passage 36, Fig. 2, leading into passage 33. The air intake of the bleeder is shown at passage 35, Fig. 2. With the carburetor in the position as shown, the internal combustion engine is acting largely as an air suction pump, so that the reduction in pressure below atmospheric above throttle valve 1 may be equivalent to a 20 inch mercury column. It may here be remarked that with throttle valve full open this reduction in pressure will fall to about 2" mercury column. If the auxiliary idling apparatus as a whole be considered as a diminutive carburetor operating under high suction pressure the analysis is simple. In the position as shown in Fig. 2 the discharge is passage 3|, the air intakes are passages 32 and bleeder passage 36. The fuel intake is of course through metering valve 31. .As the intake passages are larger than the single discharge one, the reduction in pressure within 33 is less than the reduction in the carburetor above the throttle valve, and this latter suction pressure is not exerted upon the metered fuel intake passage. Upon a further opening of the throttle valve, which upon opening turns in a clock-wise direction, the upper edge positions itself below passage 32, thus changing the passage from an intake into a discharge passage. The discharge ducts now become greater than the intake and the full reduction of pressure above the throttle valve 1 is transmitted to the fuel intake passage causing greater through. This compensates for the less reduction of pressure above throttle valve 1, and the extra air dilution due to the opening thereof. Upon further opening of the throttle valve the reduction in pressure decreases and the diminutive idling carburetor automatically cuts itself out of the system as the main carburetor, or carburetor proper, cuts itself in.

Having thus described my invention, what I claim is:-

1. In a carburetor, a secondary air and fuel mixing passage, in combination with an inductor primary main fuel passage, said secondary air and fuel mixing passage being constricted .35 into a narrow throat, into which throat from" around the periphery thereof is discharged 2. thin film or sheet of liquid from a circular reservoir surrounding said throat and opening therein through a narrow circular convergence inwardly ervoir, means for supplying said reservoir with a properly metered supply of liquid fuel, a nozzle above said throat progressively increasing in cross section upward, a screen upon the top of,

said nozzle for the purpose of producing a uniform velocity across a right section of said nozzle passage, and for the purpose of further atomizing fuel particles upon impact thereon, and also for retarding the velocity of these fuel particles, that they may have their sluggish products of evaporation that envelops them swept away by the more rapid air current, and re-contacted with a fresh air supply avid for fuel vapor, said screen also to act as a wardly directed air pulsations or surges within the upper part of the carburetor, substantially as described.

2. In a carburetor in combination with a throttle valve and main intake air passage, a means for either momentry closure or partial restriction of flow of the main air passage, said closure being proportionately to the amplitude and velocity of opening of said throttle valve and timed therewith, consisting of cam means, connected with said throttle valve, depressing a plunger within a hollow cylinder, said cylinder being passaged for a restricted fuel flow therethrough to the fuel chamber, said cylinder being wholly or partially depressed with the plunger by means of the fuel entrapped within said cylinder, means for transmitting the motion of said cylinder to a Venturi like sleeve, in which said motion controllably closes said primary intake air passage, and spring slot, formed by the of the walls of said res mild battle for any down-.

means for restoring said mechanismv .20 fuel flow thereto its normal open scribed.

3. A carburetor provided with a fuel chamber, a main intake air passage, a throttle valve, means for momentary closure of flow of air in the main air passage, lever means for opening and closing said throttle valve, cam means attached to said lever means for depressing a plunger, said plunger normally held in place by spring means against said cam, said cam depressing said plunger on opening of the throttle valve, said plunger in turn transmitting motion through a fluid connection to a small ported, movable cylinder, said cylinder being connected to a venturi which moves therewith, said movable Venturi member held in normal position by spring means, lever means attached to said Venturi member for lowering or raising same, resulting in the closing or opening of the air intake, an upper and a lower plate provided with a passage in the shape of a nozzle progressively increasing in cross-section upward, said nozzle being capped with screen means, said plates being further provided with a narrow throat and a fuel reservoir circular in form with converging walls opening into said throat for discharging a thin sheet of mixture, a secondary air and fuel passage, passages for the entrance of fuel and air into said reservoir, needlevalves for the proper metering of the fuel, an idling diminutive carburetor, passages leading from the fuel position, substantially as desupply to the main air passage and there opening.

therein with two openings one above the other whereupon a certain opening of said throttle valve the diminutive idling carburetor is automatically cut out, as and for the purposes described.

4. In a carburetor having an air inlet and a mixture outlet, a throttlevalve in and controlling said mixture outlet, a choke valve in and controlling said air inlet, mechanism for opening and closing said throttle, a movable hollow cylinder adapted to contain a fluid and connected to said choke, a plunger movable in said cylinder, means operated by the throttle opening and closing mechanism to move said plunger to exert a pressure upon the fluid in said cylinder when the throttle is opened, thereby causing said cylinder to move said choke from its normal position in proportion to the amplitude and rapidity of the throttle valve opening displacement, means for causing the plunger to move in a direction away from the cylinder when the throttle is closed, said cylinder having a restricted orifice in the wall thereof through which fluid is adapted to pass into and out of said cylinder, and means for automatically restoring said cylinder and choke valve to the normal position of said choke independently of the position of said plunger within said cylinder, as and for the purpose described.

5. In a carburetor having an air inlet and a mixture outlet, a throttle valve in and controlling said mixture outlet, a choke valve in and controlling said air inlet, mechanism for opening and closing said throttle, a movable hollow cylinder adapted to contain a fluid and connected to said choke, a plunger movable in said cylinder, means operated by the throttle opening and closing mechanism to move said plunger to exert a pressure upon the fluid in said cylinder when the throttle is opened, thereby causing said cylinder to move said choke from its normal open position in proportion to the amplitude and rapidity of the throttle valve opening displacement, means for causing the plunger to move in a direction away from the cylinder when the throttle is closed, said cylinder having a restricted orifice in the wall thereof through which fluid is adapted to pass into and out of said cylinder, and means for automatically restoring said cylinder and choke valve to the normal open position of said'choke independently of the position of said plunger Within said cylinder, as and for the purpose described.

LAURENCE R. EBERT.

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