US1816070A - Carburetor - Google Patents

Description

July 28, 1931. 0, c, E Y 1,816,070

CAHBURETOR Filed April 27, 1923 I 5 sheets-Sheet 1 thy July 28, 1931. i 0, BERRY Q 1,816,070

CARBURETOR Filed April 27, 1923 I5 Sheets-Sheet 3 l'llllii wag. as.

Patented July 28, 1 931 OTTO CARTER BERRY, OF INDIANAPOLIS,

PATENT OFFIE INDIANA, ASSIGNOR TO THE WHEELER- SCHEBLEB CARIBUBETOB 00., OF INDIANAPOLIS, INDIANA, A CORPORATION OF INDIANA Application filed April 27,

It is well known among carburetor engi' neers that an internal combustion engine which receives its supply of explosive mixture through a liquid-fuel carburetor requires a mixture much richer in fuel in starting cold than is necessary for best performance after it is thoroughly warmed up.

It isalso well established that the mixture required for maximum power is considerably richer than that for maximum economy.

It is also well known that when the throttle of a carburetor is suddenly opened wider, at least a portion of the gasoline falls behind. the air in its passage through the intake manifold of the engine and collects on the manifold walls. rarily impoverished mixture at the engine cylinders, even though the proportions are 0 maintained at the carburetor, and this is often accompanied by a temporary lack of power on the part of the engine or even by the stalling of the engine.

' It is also well known that in the case of 5 a carburetor having an air-valve, unless adequate means are provided to prevent it, the air-valve will flutter when the engine is running at low speeds under heavy load, and

that this fluttering of the air-valve will up-,.

'set the proportions of the fuel and air mixture.

For these and other reasons, unless special provisions are made in the design of the carburetor, the use oflean and economical mixtures will result in operating difficulties, among which are the following:

(1) The engine will be hard to start when itis cold.

(2) The performance of the engine will be poor and difiicult to control during the warming-up period.

(3) The engine will be unable to respond immediately and positively to a sudden demand for greater power, especially when it h'as previously been running at a low speed.

(4), The engine will lack power under a heavy pull, when it is so adjusted as to give maximum economy under ordinary driving conditions. I

(5) The engine will be unable to perform This results in a tempo- 'vention; Fig. 2 is a plan thereof;

1923. Serial No. 635,013.

properly at low speed under a heavy-load. It is the object of my invention to provide means for obviating all these difficulties, and to roduce a carburetor that will meet all the ollowing requirements:

(1) Furnish a well-atomized mixture of proper richness through a very wide range of rates of flow of the air through the carburetor.

(2) Furnish a mixture of such proportions as to produce maximum economy when the engine is running at part throttle.

(3) Furnish a mixture of such richness as to produce maximum power when the engine is running with a wide-open throttle.

(4) Furnish a temporarily enriched mixture during periods of acceleration, whether the acceleration starts from low or high engine-speeds.

(5) Provide a means that can be operated from the drivers seat to enrich the mixture throughout the range for startin and for gradually reducing the amounto such enrlchment during the period of warming up.

(6) Provide a means of damping out the fluttering of the air valve. The accompanying drawings illustrate my invention, and show a preferred embodiment thereof. In such drawings: Fig. 1 is an elevation of a carburetor embodying m inig. 3 1s a vertical longitudinal section on the .line 3--3 ofFig. 2; Fig. 4 is a transverse section on the line H of Fig. 3; Fig. 5 is a partial section illustrating one form of the fuel-metering mechanism; Fig: 6 is a partial vertical longitudinal section showing the position of the metering mechanism when the auxiliary-air valve is partly open; Fig. 7 is a partial section similar to Fig. 5,; but with the partsshifted to show the effect on the metering mechanism of throwing the fulcrum-arm to the position for a rich mixture, as when'the dash-control is pulled out for starting; Fig. 8 is a transverse section on the line 88 of Fig. 6; Fig. 9 is a partial vertical section showin one arrangement for obtaining an idle ad justment; F ig. 10 is a transverse section on the line 10-10 of Fig. 9; 11 is a verv tical section through the auxiliary-air valve showing the metering orifice tor the accelerating device; and Fig. 12 is a fragmentary section on the line l2-l2 of Fig. l.

My carburetor has a main body 1 and a float bowl 2. Air may enter the carburetor in two ways.' It may enter (Fig. 3) through the fixed-air passageway, made up of an inlet 3, a passage 4, and. a venturi 5, picking up and atomizing the gasoline at the end of a gasoline nozzle 6; and, when this passageway is not large enough, by a variable auxiliary-air passageway 8 having at its entrance a spring-seated air valve Y which will be depressed to allow such air to enter through this auxiliary-air passageway 8 as is required. In either case, the air passes through the body of the carburetor past a throttle 9 and out through a mixture-discharge opening 10..

The gasoline enters the float-bowl. 2 through a strainer cap 11 past a float-needle l2, and the gasoline level is regulated by a tloat l3ope-rating said float-needle.

From the float-bowl, the gasoline is drawn through the passageway 14 (Figs. 4, 5, and 12), past a tapered needle or meterin -pin 15, and is metered at the circular orifice 1d at the top of the passageway 14:. It then passes through a cross-drilled hole 17 (Figs. 1 and 12) and the gasoline nozzle 6 (Fig. 3) into the .air stream in the throat of the venturi 5, and thence on through the carburetor with the air. The gasolinev needlel may have a long cylindrical section 18 (Fig. 5) by which it is guided, so that it is always (oncentrically located in the metering orifice l6. a

As the rate of flow of. air through the carburetor is changed, the air and gasoline must be kept in theproper proportions. This is done as follows: To the auxiliaryair-valve 7 is fixed an arm 19 (Fig. 3) which is pivoted to one end of a proportioning lever 20. This proportioning-lever passes through and has a close sliding fit in a trunnion-block 21, which in turn is pivot-ally mounted on a fulcrum-pin 22 in the lower end of a pivotally adjustable fulcrum-arm w 23. On the other end of the proportioninglever is another sliding trunnion-block 21, which is pivotally attached to the top of the metering-pin l5 bye. pin 24, (Fig. 5). Thus as the air-valve 7 moves, the proportioninglever turns about the pin 22 and gives to the metering-pin a motion that is in proportion to that of the air-valve; and the proportionin -lever slides slightly in the trunnion- blocks 21 and 21* as required in this movement.

The pressure differential causing the air to flow past the air-valve, and the suction causing the fuel to low past the meteringpin, bear substantially the same relation to each other at all rates of flow of the air rate of air-flow, it isusually necessary to.

vary from a straight-taper the shape of either the metering-pin or the auxiliary-airpassageway. I usually change the latter, as

it is so much larger and therefore so much less sensitive" to small changes; and use a straight-taperedmetering-pin.

The methodogf procedure in working out the proper shape for the inner surface'ot the auxiliary-air passageway is as follows: Tests are run at a large number of difi'erent rates of flow of air'through the carburetor, and a record made of the weight of air and of fuel that passed during each test. From these figures the ratio of the fuel to air in the mixture is computed for each rate of air fiow. Suppose now that the mixture is found to be too rich at the articular position of the air-valve shown in Fig. 6. The inner surface 25 of the auxiliary-air passageway is then hollowed out so as to provide a larger opening past the valve'in this position, until the mixture is brought to the required proportions. When the mixture is too lean the reverse action is taken. By this means the richness of mixture obtained at each and every flow-rate is brought to the desired oint and the carburetor is made to follow t e requirements of the engine with-great accuracy. 1

There are a number of methods of measuring the amount of air and fuel passing through a carburetor. and of simultaneously determining the excellence of the performance of the engine. These methods are well understood by engineers and any one of them may bemused when working out the proper shape of the air funnel. Engineers are also familiar with the methods of determining whether the mixture is richer or leaner than they desire for any given running'conditions, or whether it is just right. In determining the proper shape of the inner'surface of the air funnel it is therefore necessary for the engineer skilled in this art to determine by test the mixture requirement of an engine at each of a large series of difierent rates of air liow through the carburetor, and then by the above mentioned experimental means, determine the shape of .to give the desired mixture when-the fulcrum-arm 23 is substantially at right angles with the proportioning-lever 20 when the auxiliary-air valve is closed, so that a small motion of the trunnion block 21 in either direction will not change the position of the metering-pin and thus affect the idle adjustment. Shifting the trunnion block 21 toward the air-valve, as indicated in Fig. 5, will cause the metering-pin to move farther for a given air-valve motion and result .in an enriched mixture at all rates ofair-fiow.

In order to provide a wide range of flowrate capacities, the fixed-air opening through the venturi 5 is made small, and the auxi'liary air-valve 7 is made. large.

The seating spring 26 of the air-valve 7 is made strong enough so that during operation the vacuum .in the body of the carburetor will be suflicient to atomize the fuel at the throat-of the venturi 5, even at very low rates of air flow. 1

' A dash-pot piston 28 (Fig. 3) in a fuel.

dash-pot 27 is connected to the air-valve 7, and serves a double purpose-to keep the air-valve from fluttering, and also to aid in accelerating with a lean mixture. The former of these two purposes is obtained by an obvious dash- 0t effect. The latter is accomplished as ollows: When the dashpot 1piston 28 is depressed, it forces fuel up t rough a passageway 29 1n the pistonstem 30 and into the interior of a hollow nut or chamber 31; which is higher than the fuel level in the float bowl 2, and above the air-valve 7. The size of the passageway 29 is experimentally determined so that in practice it will deliver a satisfactory amount "of fuel to the chamber 31. The chamber or nut. 31 may in some cases have a vent 32.

The gasoline then flows out through a metering-orifice 33 (Figs. 3, 6, and 11) and through a passageway 34 (Fig. 6) to a point 35 at the edge of the air-valve 7, where it is thoroughl atomized as it enters the air stream. n this, ay the mixture is temporarily enriched d rlng periods'of acceleration, by temporarily supplying gasoline to the air passing the air-valve 7.

A check-valve 36 (Fig. 6). keeps the gasoline from returning to the dash-pot 27, and

- prevents air from getting under the dash-- pot piston .28-while it is being raised by the spring 26.

It is desirable to have the air-valve 7 open more slowly than it closes. This is accom plished by havingthe thin circular disk 37 placed below the holes 38 in the piston. 28, and capable of moving a very short distance vertically relative to such piston. This makes an effective check-valve.

During wide-open-throttle running at to slope toward the venturi 5 from all sides,

to form a sump 39. Small holes 40 are drilled into the venturi 5 opposite the bottom of this sump 39, and open into the inside of the venturi just above the throat. The suction of the venturi is high at this point, and draws in any fuel that collects in the sump 39,atomizing it and re-introducing it into the air stream.

A small percent of the atomized fuel tends to collect on the walls of the venturi and-leave the upper edge in droplets. -To prevent the formation of these droplets, the upper end of the venturi is turned inward in a sharp edge 41, which re-introduces this.

an adjusting-screw 45 in a lug 46 by a spring 46. The position of the screw 45 affects the position of the fulcrum-pin 22, and so governs the richness of the mixture throughout the range of the carburetor at partly closed throttle positions. The arm 43 is acted on by a cam 47 on the throttleshaft 48, in such a way that when the throttle 9 is wide open the lever 43 is depressed, the trunnion-block 21 and fulcrum pin 22 are moved toward the air-valve, and in consequence the fuel-needle is given a greater lift for a given air-valve motion, and the mixture is made richer. The amount of this enrichment and the point in the throttle movement where it starts may be changed by adjusting the screw 50.

The short are of movement of the fulcrum pin 22 about the shaft 42 in this adjustment is fairly close to a straight line parallel to the proportioning lever 20 when the air-valve 7 is closed, so that then such shifting of the fulcrum pin does not greatly tive v without materially changing the proportionate part of the air-valve motion transmitted to said metering-pin. it IS therefore possible to change the idle adjustment without greatly afifecting'the mixture at hi her rates of flow. This idle adjustment thus varies the relative positions of the fuel-valve and its seat for a given air-valve position. The movement or" the tulcrum-arm-shaft 42 obtained by this idle adjustment is fairly close to perpendicular to the proportioning lever 20, to minimize the shifting which produces of the fulcrum-pin 22 along such proportioning lever.

To obtain the rich mixture for starting a cold engine, a dash adjustment is provided which connects to the arm 43 through a Wire 53, (Fig. l). Pulling down on the wire 53 will turn the fulcrum-arm 23 and shift-the trunnion-block 21 and tulcrunnpin 22 toward the air-valve 7 to increase the lift of the fuel-needle 15 for a given opening of such air-valve, and (because of the relatively large angular extent of such turning} even to cause a considerable hit of such needle-valve while the air-valve '7! is still on its seat, which results efiectively in an enriched starting mixture, as desired,

ll claim as my invention 1. ln a carburetor, the combination a casing having a mixing chamber, a throttle valve, and a throttle shaft, of a nozzle discharging fuel which is delivered into said mixing chamber, a metering-pin for controlling the quantity of fuel delivered by said nozzle, an air-valve, lever-means for transmitting motion from said air-valve to said metering-pin, a fulcrum for said levermeans, said mixlng chamber having an airinlet opening with whichsaid-air-valve cooperates, and means operated from said throttle-shaft for changing the position of said fulcrum to enrich the mixture when said throttle-valve approaches wide-open position.

2. In a carburetor, the combination of a mixing chamber, a throttle, a fuel nozzle discharging fuel which, is delivered into said mixing chamber, said mixing chamber being provided with an air-inlet opening, an air-valve tending to close said air-inlet opening but movable to vary its efiective size,

a fuel-valve controlling the fuel discharged from said fuel nozzle, means interconnecting said fuel-valve and said air-valve so that the former i actuated by movements of the latter, and means operated by said throttle for varying the proportionate part fuel whic relative of sail air-valve movement which is transmitted by said means to said fuel-valve.

3. in a carburetor, the combination of mixing chamber, a throttle, a fuel nozzle discharging fuel w is delivered into said mixing chamber, sa; mixing chamber beingprovided with an air-inlet opening, an air-valve to close said air-inlet opening but movable to vary its effective size, a fuel-valve controlling the fuel discharged from said fuel nozzle, a lever interconnect ing said tuehvalve and said air-valve, a fulcrum on which said lever is mounted, a fulcrum-arm which carries such fulcrum, a fulcrum-arm shaft about which said fulcrum-arm rotates, an operating arm on said fulcrum-arm shaft, and a cam operatedby movements of said throttle for actuating said operating arm to enrich the mixture when said throttle is at or near wide-open position,

4-, in a carburetor, the combination of a mixing chamber, a fuel nozzle discharging is delivered into said mixing chamber, said mixing chamber being provided with an air-inlet opening, an air-valve tending" to close said air-inlet opening but movable to vary its effective size, a fuelvalve controlling the fuel discharged from said fuel nozzle, a lever interconnecting said fuel valve and said air-valve, a fulcrum on which said lever is mounted, and a plurality operating devices for independently the location of said fulcrum.

carburetor, the combination or" a chamber, a throttle, a fuel nozzle one fuel which is delivered into 'd mixing chamber, said mixing chamber being provided with an air-inlet opening, an air-valve tending to close said air-inlet opening but movable to vary its effective size, a fuel-valve controlling the fuel discharged from said fuel nozzle, a lever interconnecting said fuel-valve and said airvalve, a fulcrum on which said lever is mounted, means for operating said throttle, and means for shifting the position of said fulcrum by the operation of the throttle and independently of'the throttle.

6. In a carburetor, the combination of a mixing chamber, a fuel-valve and an airvalve controlling respectively quantities of fuel and air delivered to said mixing chamher, a lever interconnecting said two valves, a fulcrum for said lever, and two separately operable means for shifting said fulcrum substantially lengthwise of and substantially transverse to said lever respectively. 7. ln a carburetor, the combination of a mixin chamber, a fuel-valve and an airvalve controlling respectively quantities of :fuel and air delivered to said mixing chamber, a. lever interconnecting said two valves, a fulcrum for said lever comprising a pivoted sleeve in which said lover is slidably .lOG

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. 2Q fice and leading from said elevated fuel mounted, and a plurality of adjustablecarrying means for said sleeve for shifting it substantially lengthwise andcrosswise of- Y said lever.

8. The vcombination set forth in claim 7, wherein said fulcrum-carrying means comprises a pivoted arm to which a sleeve is pivoted,'an eccentrically adjustable bearing for said pivoted arm, and means for turning said arm to adjust said fulcrum.

9. In a carbu'retor,.an accelerating device made up of a combination of a fuel'dashpot chamber, an auxiliary fuel chamber above the fuel level of-the carburetor, a passageway, from said dash-pot chamber to said fuel chamber, an air-valve, a piston in said dash-pot chamber so actuated by an' OTTO CARTER BERRY.

opening motion of said air-valve as to force fuel into said elevated fuel chamber, and a passageway provided with a" metering orichamber to the air stream entering the carburetor.v

10. -In a carburetor, an acceleratmg device made up of a. combination of a fueldashpot, chamber, an air-valve, an auxiliary fuel chamber above-said air-valve, a passageway leading from said dash-pot chamber to said elevated chamber, a check valve in said passagewa-y, a piston -'in said dash-pot chamber so actuated by an opening movement of said 'said air-valve.

air-valve as to force fuel into said elevated fuelchamber, and a passageway provided with a metering orifice and leading from said elevated fuel-chamber to the. edge of 11. In a carburetor, the combination of a mixing chamber, a throttle, a fuel nozzle discharging fuel whichisdelivered'into said mixing chamber, said mixing chamber being provided" with an air inlet, an air-valve tending to close said air-inlet but movable to vary its effective size, said air inlet having afunnel-like interior surface specially of said shaped to regulate the proportionate amount of air flowing at each consecutive position air-valve, a fuel-valve controlling \the fuel discharged from said fuel'nozzle,

means interconnecting said fuel-valve and trolled in" accordance with adjustment of said throttle for varyingthe proportionate ,part of said air valve movement which is transmitted by said means to said fuel valve.

12. In a carburetor in combination, a mixing chamber, a fixed air inlet to said mixing chamber, a variable air inlet to said mixing chamber comprising a valve which by its movement in a contoured passageway adjusts the efiective area thereof,.a reservoir for fuel, a nozzle supplied from said reservoir and feeding into said fixed air inlet,

' mechanical means to modify the flow of fuel from said nozzle mechanically connected .said air-valve so that the former is actuated 'by movement of the latter, and means con-

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