US1869785A - Carburetor - Google Patents

Description

Aug. 2, 1932- 'w. M. THOMAS CARBURETOR Filed June 20. 1930 gwuatov William /1. Thom&1 i

Patented Aug. 2, 1932 s'r'rss UNITE VI'ILLIAM M. THOMAS, OF ALBUQUERQUE, NEW MEXICO, ASSIGNOR OF ONE-FOURTH TO FRED WQLEE AND ONE-FOURTH T0 BRYAN G. JOHNSON, BOTH. OF ALBUQUERQUE,

NEW MEXICO Application filed June 20,

This invention relates to a device for intimately mixing a liquid and a gas, and more particularly to the type of mixers known as carburetors, which are extensively used on internal combustion engines for automobiles for mixing a liquid fuel such as gasoline with a gas, such as air, with which it will explosively react under proper conditions.

In the type of internal combustion engine ordinarily used in automobiles, the engine is so designed that its speed and the consequent speed of the car may be varied within a rather wide range by merely varying the amount of explosive mixture supplied to the engine by the carburetor. The carburetor, therefore, must be designed to supply this explosive mixture at a rate which may be varied at the will of the operator.

In order that the operator may control the carburetor to cause it to supply to the engine an amount of explosive mixture just sufficient to operate the engine at the desired speed, the ordinary carburetor has in the passage through which the gas passes from the carburetor to the internal combustion engine a butterfly valve which the operator of the automobile may control manually, opening or closing this valve in order to accelerate or slow down the engine.

The function of the carburetor then is to supply to this passage a mixture, usually of gasoline and air, in sufficient quantities and in correct proportions at all speeds. The usual type of carburetor attempts to accomplish this result by injecting into the air passage a finely divided spray of the liquid fuel. A common method of doing this consists in maintaining in the carburetor a supply of liquid fuel at a constant pressure by the use of the conventional float chamber. From this float chamber the fuel is supplied to a nozzle or nozzles which discharge into theair passage before it reaches the butterfly valve. The discharge ends of these nozzlesare generally so located and so directed that the fuel will be dischar ed therefrom only when a suction is create at their discharge ends by the movement of air through the-passage. As the manually. controlled valve is'opened wider, the movement of air through the pas- CARBURETOR 1930. Serial No. 462,536.

sage becomes more rapid, thesuction greater and hence the amount of fuel sucked through the nozzles into the air in the passage is also greater. r j I It may be noted here, however, that the explosive mixture used by an internal combustion engine produces its maximum effect only when the percentage of fuel in the explosive mixture is exactly right for the particular speed at which the engine is operating and that the same mixture will not give maximum power at all speeds. With a system of carburetion such as above set out, ,it is the usual practice to adjust or proportion the fuel nozzles so that a proper amount of fuel is injected into the air to give maximum efficiency at the average running speed. With such systems there is no assurance nor any reason to believe that the proper mixture will be supplied to the engine over any appreciable range of speeds. The fact that a proper mixture is not supplied to the engine at all times is clearly shown by the fact that frequently when the engine is running at an idling speed, and the butterfly valve quickly opened, the engine will stall because an improperly proportioned mixture has been supplied thereto. 7

In some of the carburetors ofthe aforementioned'type, in order to produce a finer dispersion of the fuel in theair, the passage in which the dispersion is made has been formed in the shape of a Venturi tube, that is with'a smaller or constricted section which tapers gradually into a section of larger cross-section or diameter. The nozzles from Which the fuel is dispersed or atomized are then located near the smallest part of the constriction, and as the expansion of the air upon passing the constriction increases the suction upon these nozzles, they may conse-' quently be made smaller and still supply the same amount of fuel. It has been found that these smaller nozzles, together with-the expansion of the air, cause a more intimate mixture of the air and fuel and consequently a better and more powerful explosive mix-' ture.

The present invention relates to means for V obtaining anintimate mixture of the air and i" liquid fuel, and to such means as will also ensure that the proportion of the dispersed fuel in the explosive mixture will at all times be exactly that required for maximum efiiciency, regardless of the speed at which the engine is running. This is accomplished by a novel construction of that section of passage through which the air or other gas travels before it reaches the manually operated butterfly valve, and in which section of passage the gasoline or other fuel is atomized or dis persed in the air.

As already stated, by varying the shape of this passage and the spacing and arrangement of nozzles in the passage, it has been found possible to draw from the nozzles an amount of fuel equal to almost any desired percentage of the air passing through the passage. However, the amount of air passing through this passage varies with the speed of the motor and for the most eflicient operation it is essential that as the speed of the motor or rate of flow of air through this passage varies the amount of fuel drawn from the nozzle or nozzles be varied in such an amount that there is supplied to the motor, at whatever rate of speed it is revolving, a supply of ex plosive mixture containing exactly the right proportion of fuel and in which the fuel is completely dispersed in the air.

In the present carburetor, the section of passage through which the air travels before reaching the manually operated valve contains a compartively short constricted portion which flares abruptly into a much wider section forming a comparatively steeply tapered shoulder. In this tapered shoulder are a series of air passages which are constantly maintained unobstructed and through which a part of the incoming air is at all speeds directed toward the center of the passage, and angularly onward through the passage to ward the manually operated valve. These passages open at their other ends into a chamber which, in turn, communicates directly with the main passage on the opposite side of the constricted portion. The constricted portion is so shaped as to form, in conjunction with the main passage, two concentric passages, one through the center of the con strict-ed portion which is generally the larger air passage, and a second surrounding passage which supplies air to the openings through the shoulder and provides means for separating a portion of the incoming air for feeding the supplemental openings in the shoulder, and also for providing the necessary resistance to the air passing through said openings- The fuel nozzles terminate near the constricted part of the passage and are di rected toward the point at whichthe streams of gases flowing through the openings in the shoulder converge. It has been found that such a construction not only gives a very F fine atomization of the fuel, but also causes the fuel to be supplied at exactly the proper proportion for maximum efliciency regardless of the speed at which the engine is running.-

For a specific embodiment of the applicants invention as applied to a carburetor of the type ordinarily used on automotive vehicles reference may be had to the accompanying drawing in which:

Fig. 1 illustrates a carburetor of applicants new improved type shown in side elevation with certain parts in cross section;

Fig. 2 is a top sectional view of the same construction taken on the line 2-2 of Fig. 1.

In the drawing the carburetor is composed of two castings 1 and 2 which house a suitable float mechanism in chamber 3 which float mechanism supplies liquid fuel to the mixing device at a constant pressure. This float chamber is of the conventional type and is not shown in detail. The castings 1 and 2 further provide an air passage 4 through which air is adapted to enter at the end 5 of the air passage which is located in the casting l and through which passage the air is conveyed to an exit 6 in the casting 2 from which it is led to the internal combustion engine.

Near the end 5 of this passage is located the conventional choke valve 7 which is adapted to reduce or cut off the supply of incoming air and near the exit 6 of the passage is located a butterfly valve 8 for regulating the amount of explosive mixture supplied to the engine. Adjacent the butterfly valve 8 is a small opening 9 through which a small amount of explosive mixture is supplied for idling.

Located within the passage 4 in the vertical portion thereof and extending partly into both of the castings 1 and 2 is located a sleeve 10 through which the incoming air passes upwardly and during. which passage it is mixed with the required amount of liquid fuel. Near the lower end of the sleeve 10 is located a constriction 11 which is ring shaped and which forms a short constricted opening 17 through which the greater portion of the air must pass on its way to the engine. This constricted portion is of general Venturi shape but flares abruptly above its point of greatest constriction forming a shoulder 12 in the sleeve 10 and flares somewhat less below the point of greatest constriction. Openings 13 situated in the shoulder formed by the constriction direct air passing through them in converging lines upwardly and toward the center of the sleeve 10. At their opposite ends the openings 13 open into an annular recess 14 formed between the lower part of the constriction 11 and the outer shell of the sleeve 10. The constriction 11 and the sleeve 10 are illustrated as one piece but may obviously be made in two parts to simplify manufacture. Nozzles 15 and 16 are located in the bottom of the passage 4 and extend upwardly into the constricted opening 17, ter- 1 plosive mixture to the engine minating at points adjacent the point of greatest constriction and supplying liquid fuel to the incoming air at this point. p

The major steps in the operation of this device are fairly obvious. The air passes through the passage 4 through the constricted opening. 17 and the recess 14 and openings 13 into the upper part of the sleeve 10 and,

then by the butterfly valve 8 and into the engine. As the air passes through the opening 17 into the. upper part of sleeve 10 itis permitted to expand suddenly and creates a by the engine. IIowever, the velocity of air through these openings is also governed in part by the resistance ofiered by the openings to the passage of air therethrough and by properly proportioning the size of the openings 13 and the recess 14 to the size of the constricted opening 17 it has been found possible to so proportion the flow of air through the openings 13 and the constricted opening 17 that the proper proportion of air will pass through these respective openings at all speeds to draw from the nozzles 15 and 16 the desired amount of fuel for proper engine performance and produce the proper mixing of the atomized or vaporized fuel and air at all speeds. 7

One of the distinct advantages of this construction is in the short constricted portion which causes a minimum of resistance to the incoming air and therefore supplies the ex quickly and with a minimum of resistance.

The device is relatively simple in construction, all of its parts are fixed and no levers, cams, gears or springs are present to get out of order and yet merely by the suction produced in the upper part of the sleeve 10 this novel constructionadjusts the proportion of fuel and air to be mixed and provides a means for intimately mixing them in the desired proportions under all normal operating conditions of the engine. I

Having thus described my invention, I claim: v

1. In a carburetor for internal combustion engines, a main air passage therethrough, means forming a constricted portion within said passage, said means having an outwardly and onwardly directed shoulder leading from the constricted portion to the wall of said passage, a fuel supplying nozzle in said 7 main air passage, said nozzle having its discharge end terminating adjacent the portion of greatest constriction, an air chamber,

opening into the main air passage at all engine speeds, surrounding at least a part of the constricted portion of the main air passage, said shoulder having openings there-' through adjacent the constricted portion for the continuous introduction of an auxiliary supply of air from'said surrounding chamber into the fuel and air 'mixturejin the main passage, the openings in said shoulders emerging adjacent the point. of greatest constriction in said main air passage;

2. In a carburetor, a main passage, a

shoulder in said main passage forming a constricted opening therein, a chamber opening into said main passage and surrounding at least a portion of said shoulder at one end thereof, the other end of said shoulder flaring from said constricted openingto the wall of said passage at an angle greater than 45 to the center line of said passage, said shoulder having a plurality of small supplemental openings forming the only connection be- I tween said chamber and the passage on the other side of said shoulder.

In testimony whereof I aflix my signature. WILLIAM M. THOMAS.

Images