Carburetor

Dec. 4, 1934. g. a wahlmark 1,983,255

CARBURETOR Filed May 25, 1929 2 Sheets-Sheet 1

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Dec. 4, 1934. g. a. wahlmark 1,983,255

CARBURETOR Filed May 25,- 1929 2 Sheets-Sheet 2

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Patented Dec. 4, 1934

1,983,255

UNITED STATES PATENT OFFICE

1.983,255 CARBURETOR &lt; Gunnar A. Wahhnark, Rockford, Ill., assignor of ^Svenson and one-third to Charles H. Rystrom, both of Rockford, III. Application May 25, 1929, Serial No. 365.869

Claims. (Cl. 261—46)

Ώιε invention relates generally to carburetors and the primary object of the invention is to provide a carburetor of simple design capable of being economically manufactured and efficiently 5 operated to increase the overall efficiency and controllability of the motor with which it is. used.

The present invention finds its greatest usefulness when applied to a carburetor for the internal combustion motor of an automobile, for in order 10 to meet the requirements of such service, a motor must be easily controlled and capable of gradual acceleration under load throughout practically its entire range of speeds. Such motors must also be economical of fuel in order to render their 15 performance fully satisfactory.

The attainment of these results with a particular motor is dependent to a great extent upon the thoroughness of the vaporization of the fuel as . ^W®^UA^{S u}P°ⁿ the richness of the fuel mixture sup20 plied to the motor at its various speeds.'

In practice the fuel discharge orifice is annular in form and is positioned within a comparatively small annular chamber formed in the fuel disf., ,^rg_f^{e me}“^b®^{r 80} that the mixing of the air and 25. fuel is initiated within this chamber. At the lower motor speeds, the air is directed past only a sm^ll arcuate section of the fuel discharge orifice so that fuel is drawn into the annular chamber and there jnixed with the air and discharged into 30 the main body of the carburetor for further mixspreadsaX^ mixing chamber wherein mixing of air creasing gradually in the Quantify S?^{d iuel is obtained} in the same manner when vaporizing action throughput the range of motor primary air, and stag^^ontro^meSer jp cud. f.Hrnt'.i'.ln nnorntiln _____:_____ .Another object is to provide a carburetor having a comparatively small chamber in which the air and fuel are initially mixed together with means to control the supply of fuel and the passage of air through the chamber so that the mixing con- 60 tiniies therein and progressively increases or spreads to different parts of the same chamber as the motor speed is increased so as to supply a uniformly increasing quantity of thoroughly mixed fuel to the motor.

Another object of the invention is to provide a carburetor embodying a fuel discharge member having a mixing chamber therein and a plurality of ducts leading therefrom arranged to be controlled and brought into operation in varying 70 numbers through the action of the sections of compression and expansion in a venturi, this result being obtained by mounting the fuel discharge member and the venturi for relative movement longitudinally of the venturi, and ar- 75 ranging the ducts so as to terminate at points spaced longitudinally of the venturi.

With such a construction it will be apparent that the quantity of fuel drawn into the carburetor for any relative positioning of the fuel discharge member and the venturi Is controlled by the number of ducts terminating on the expansion side of the Venturi throat, and this fact renders the construction particularly advantageous since it permits the designer accurately P^r°P°^rfcioning of fuel and air at * ~ ‘ .. .I-. Thus if a particular ire efficiently at a given speed is reduced, the

- . ’ — —, WMVXVl iMOUlMVl’ Or throttle operable positively to govern the relative amounts of fuel, primary air and secondary , air, the fuel discharge member having a plu- ¹gether with meansfor” dVectinraffaton^'vaiytag ffitS ^{fed from} numbers of these paths wherebv f.n inLJZ ™ ^{and brougbt into} operation as fuel passages in varying numbers as the supply .50 Another, object is ¢0 provide a carburetor having a plurality of different paths along which air

-may pass lo draw fuel into the carburetor tonumbers of these paths whereby to increase or

SS. decrease the quantity of liquid fuel supplied. > »f prlniary ώ «.Sm hy“to7«Kl“S3?. .,. -,. \ 1JLU

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Another object is to provide a carburetor embodying means to offset or equalize the effect of the motor suction on the throttle so that the movement of the throttle may be easily and ac5 curately controlled by the operator.

In the lower range of motor speeds it is usually desirable to provide for an exceedingly gradual acceleration. The throttle or control member, of the carburetor is usually actuated by the op,0 erator through a manual or foot-operated accelerator and it is often quite difficult for the operator to impart slight movement or very slow movement thereto. This results in an irregular acceleration of the motor. Another object of the ,- invention is to provide a carburetor having means ¹⁰ for actuating the throttle arranged to move the throttle very little for a given movement of the accelerator in the lower range of speeds and arranged so that the. relative amount of throttle movement increases as the accelerator is moved to its most advanced position.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings in which:

Figure 1 is a vertical central section through a carburetor embodying the preferred form of the invention taken along the line 1—1 of Fig. 2.

Fig. 2 is a transverse vertical section taken along the line 2—2 of Figs. 1 and 7.

³⁰ Fig. 3 is an enlarged fragmental section of the fuel discharge member and the sliding throttle sleeve taken along the line 1—1 of Fig. 2.

Fig. 4 is a sectional view similar to Fig. 3 showing an alternative form of the fuel discharge 3® member and throttle sleeve.

Fig. 5 is an enlarged sectional view taken along the line 5—5 of Fig. 4.

Fig. 6 is a side elevational view of the carburetor, part in central section.

⁴⁰ Fig. 7 is a plan view of the carburetor with portions of the body broken away to show the internal construction.

Fig. 8 is a diagrammatic view showing an exemplary arrangement of the fuel discharge ducts ⁴® in the fuel discharge membef.

Fig. 9 is a section through the fuel discharge member at the fuel level.

While I have shown in the accompanying drawings and will herein describe in detail the ⁵⁰ preferred embodiment of the invention together with one alternative form thereof, it is to be understood that this disclosure is given for the purpose of illustrating the invention and is not intended as a limitation of the invention to the 55 construction disclosed. In the appended claims, I aim to cover all modifications and alternative constructions falling within the spirit and scope of the invention.

In the form chosen for disclosure herein, the 60 invention is embodied in -a carburetor having a hollow body 10 providing a chamber 11 which has an intake opening 12 communicating with the atmosphere and an outlet opening 13 adapted to be connected to the intake manifold (not 65 shown) of an internal combustion motor. Thus air may be drawn through the chamber 11 of the carburetor and mixed with fuel in the desired proportion by means contained within the chamber 11 intermediate the intake opening and the 7® outlet opening.

The outlet opening 13 is formed by a vertically extending tubular portion 14 having a flange 15 at its upper end for connection with the intake manifold. The air intake 12 is cylindrical in form ,255 and extends horizontally in one direction from the bottom of the tubular portion 14. On the opposite side of the tubular portion 14 the body 10 is formed to provide a float or fuel chamber 16. The top wall 17 of the float chamber 16 is preferably removably secured in position by screws 18 and has an aperture 19 (Fig. 1) formed therein adjacent one edge in which aperture a valve device is mounted. The valve device preferably comprises a sleeve 20 having a valve seat 22 at its upper end arranged to be engaged by a valve member 21 slidably mounted in the sleeve. The sleeve 20 has an annular flange 23 formed near its lower end to engage the inner surface of the removable wall 17 and a nut 24 is threaded on the 90 upper end of the sleeve to engage the outer surface of the wall 17 to maintain the sleeve in position. A fitting 25 secured on the outside of the removable wall 17 has an opening 26 adapted for connection with the fuel supply tank (not shown). °®

The valve member 21 is actuated to maintain a constant level of fuel within the . chamber 16 by means of a float 27 mounted on one end of a lever 28, the other end of which is pivoted at 29 on lugs 30 carried by the sleeve 20. The valve member 21 19« extends downwardly out of the sleeve 20 and has a fork 31 at its lower end providing a horizontal slot which engages a roller 32 carried on the lever 28 between its pivot point and the float 27, Thus the float and valve device comprise a unitary 105 structure which may be removed or adjusted as a unit. To adjust the valve device to maintain dif, ferent levels of fuel within the chamber 16 shims may be positioned intermediate the flange 23 and the inner surface of the removable wall. HO

The float chamber 16 is connected, by means hereinafter described, with a fuel discharge member designated generally as 35 positioned within the chamber 11 beneath and in axial alinement with the tubular portion 14 which provides the 115 outlet opening, the fuel discharge member 35 serving to supply fuel to be mixed with air passing through the chamber 11. The passage of air through the chamber 11 is preferably controlled by means cooperating with the discharge mem- 121 ber 35 to close or govern the effective size of the outlet opening 13. This means preferably comprises a movable sleeve or throttle 36 supported within the chamber 11 in surrounding relation to the fuel discharge member 35 for movement along 125 a vertical path toward and away from a position in which the outlet opening 13 is substantially closed, this position being such that the carburetor supplies sufficient fuel to run the motor at a low or idling speed. ¹³⁰

The sleeve 36 is preferably supported and guided for such movement by 'means of a trunk piston 37 (Figs. 1 and 2) mounted in a vertical cylinder 38 formed in a housing 39 which extends downwardly from the body 10 in axial 135 alinement with the tubular portion 14. The lower end of the housing 39 is closed by a plate 39^a. A plurality of supports 40 formed on opposite sides of the piston 37 extend upwardly in spaced relation and are connected to the sleeve 36. 140 This construction permits the discharge member 35 to be supported in fixed position within the sleeve 36 by means of a bar 41 (Fig. 2) extending between the spaced supports 40 and secured to the bottom of the chamber 11 by screws 42. ¹⁴⁵

The slidable sleeve 36 and the discharge member 35 are preferably formed so that when the sleeve is moved downwardly to its open position, an annular Venturi passage 45 is formed between the fuel discharge member 35 and the sleeve 36

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As illustrated in the drawings, the cross bar 41 has a stem 65, the lower portion of which is threaded to receive the discharge member. A vertical bore 66 is formed in the stem 65 communicating with the horizontal bore 58 in the cross bar. This vertical bore 66 is flared outwardly at its upper end and the stem 65 is of such a height that the fuel level (Fig. 1) maintained by the float valve is slightly below the open upper end of the stem. As illustrated in Figs. 1, 3 and 4 the fuel discharge member 35 has a vertical central bore 67 in which a plug 68 is fitted. This plug has a conical lower end 69 arranged to project downwardly into the flared upper end of the bore 67 in the stem so'as to provide a narrow annular discharge orifice 70 (Figs. 3 and 9) through which fuel may be drawn from the bore 66 in the stem.

Near its upper end the stem 65 is of a smaller diameter than the bore 67 in the discharge member so as to provide an annular passage-71 (Fig. 3) about the stem, and a plurality of openings 72 are formed in the discharge member near the lower end of this reduced portion to admit air into the passage 71. The air admitted through the openings 72 may pass upwardly about the upper edge of the stem 65, and a plurality of ducts 73 extending to the outer surface of the discharge member 35 are provided for the passage of this air out of the fuel discharge member. As the air 105 passes through the openings 72 and past the upper end of the stem 65 fuel is drawn from the annular orifice 70 and is mixed with the air and discharged through some of the ducts 73. During the passage of this air the annular space 74 above the πΰ stem 65 serves as a mixing chamber for the fuel and air. ,.. ,.,

As shown in Fig. 9, the inner ends of the ducts 73 terminate at closely spaced points about the annular mixing chamber 74 so that air drawn out of the chamber 74 through any particular one of the ducts will flow past a small arcuate portion of the fuel discharge orifice 70 so as to draw fuel from that portion. To vary the amount of fuel drawn from the orifice 70 suction is applied to the ._2t ducts 73 in varying numbers so that air is drawn •along varying numbers of small arcuate sections of the orifice 70 to draw fuel therefrom. This results in a gradual spreading of the mixing action within the chamber 74 and the combustible unx- 125 ture thus formed passes through the ducts 73 into the venturi 45.

The number of ducts 73 effective as fuel discharge passages is preferably controlled by means of the venturi 45, and to this end the outer ends 130 of the ducts 73 are spaced longitudinally of the axis of the venturi. Thus when the outer end of one of the ducts 73 is positioned above the throat 50 and hence is in the expansion section of the venturi, that end of the duct will be subjected to to a pressure which is less than the pressure within the chamber 70 since that chamber communicate-,' with the compression side of the venturi. This causes air to be drawn through the duct. By moving the Venturi sleeve 36 up and down the number of ducts 73 terminating above the throat 50 may be varied with a resulting variation in the amount of fuel drawn into the mixing chambe 70 15 _t To provide for an idling mixture; one or more » thereon. The .diusUng lever ot the duets s°i .presseddetente. «^«n ΪΚthrough the venturi 45 when the sleeve is in its idling position j

1,983,255 through which air may be drawn by the engine suction.. Since this air passes directly by the fuel discharge member, it will be mixed with the fuel and hence constitutes the primary air supply.

As illustrated herein, the outside of the sleeve 36 is formed within an annular projecting portion 48 so that when the sleeve is in its open or lower position or in partially open position, a second annular Venturi passage 46 (Fig. 1) is provided between the sleeve 36 and a sleeve 47 which is positioned within the tubular portion 14 and is shaped to constitute the outer annular wall of the passage. The smallest inner diameter of the sleeve 47 is substantially the same as the greatest outer diameter of the annular portion 48 so that when the slidable sleeve 36 is in its uppermost position as shown in Fig. 2, the venturi 46 will be closed by engagement of the portion 48 with the sleeve 47.

The sleeve 47 is preferably mounted in the tubular portion 14 for sliding movement so that it may be moved downwardly from the position shown in Fig. 1 to the position shown in Fig. 6 to prevent opening of the venturi 46 by downward movement of the sliding sleeve 36. Thus the sleeve 47 serves, as a “choke” to cut off the supply of secondary air which normally passes through the venturi 46 and provides a rich fuel mixture suitable for starting or warming up the motor.

The inner surface of the slidable throttle sleeve 36 is of substantially the same diameter from the top down to a point below the projecting portion 48, and then this inner surface slopes inwardly to a throat portion 50 adjacent the lower end of the sleeve and then outwardly so as to form the outer annular surface of the venturi 45, the inner annular surface of which is formed by the fuel discharge member 35.

The fuel discharge member 35 is circular in horizontal cross section and is of greater diameter at substantially the midpoint of its height so that in vertical cross section it is substantially diamond shaped. The member 35 is mounted in the chamber 11 so that when the sliding sleeve 36 is in its uppermost position as shown in Fig. 2, the portion 50 on the sliding sleeve 36 lies opposite the largest portion of the discharge member and leaves a very small annular throat opening 45 (see Fig. 3) through wL.ch sufficient air may pass to provide an idling fuel mixture for the motor. From the region of largest diameter the fuel discharge member tapers inwardly and upwardly to provide a gradually increasing annular space between its surface and the inner surface of the sliding sleeve 36. Below this region of largest diameter the fuel discharge member 35 tapers inwardly and downwardly so that during the downward movement of the sliding sleeve 36 the throat of the venturi 45 is always in the plane of the portion 50. .

The float chamber 16 is connected with the fuel discharge member 35 by means of a passage comprising a bore 55 formed in the body 10 (Fig. 7), a short substantially vertical bore 56 (Fig. 2), an upwardly inclined bore 57, and a horizontal ' bore 58 formed in the cross bar 41 which supports the fuel discharge member 35.

The bore 56 has a restricted portion at its lower end forming a valve seat for a needle valve 59 > (Fig. 2) positioned within the bore 56 and extending upwardly out of the body 10 to receive an adjusting lever 60 thereon.

has a spring-i engaging notches 62 formed on an 5 63 so that the fuel supply may be regulated.

1,983,255 will draw a small amount of fuel through such a duct.

Thus it will be seen that by varying the number of ducts 73 which terminate at different levels 5 on the discharge member 35 the carburetor may be designed to provide a combustible mixture which will vary in accordance with a predetermined standard set by the size and type of motor with which the carburetor is to be used.

In Fig. 8, an exemplary distribution or arrangement of the ducts 73 is shown diagrammatically so as to indicate the number of ducts effective as fuel discharge passages for different positions of the Venturi sleeve 36. Thus when the Venturi 15 sleeve 36 is in its upper or idling position so that its throat 50 is positioned at the horizontal line marked “Idling”, the outer ends of three of the ducts 73 are positioned above or at the expansion side of the Venturi throat. When the Venturi 20 sleeve 36 is moved downwardly, the number of ' ducts 73 opening above the throat 50 is increased as indicated by the horizontal lines marking the various positions of the throat 50. Thus when the sleeve is in its lowermost position indicated 25 as “Full throttle” in Fig. 8, all of the ducts 73 open above the throat 50 and are effective as fuel discharge passages.

For the purpose of simplifying the manufacture of the discharge member 35 the plug 68 may 30 be formed with a plurality of longitudinal grooves 75 therein as shown inFigs. 4 and 5. Thus these grooves will cooperate with the sides of the bore 67 in the discharge member 35 to form a part of the ducts 73^a which are similar to the ducts 73 35 shown in Figs. 1 to 3, and the ducts are completed by a plurality of bores 76 formed in peripherally spaced relation in the discharge member 35 substantially perpendicular to'the axis of the vertical bore 67. These bores 76 are formed at different 40 levels so that the carburetor functions the same in this form as in the form illustrated in Fig. 3. It will be noted that in both forms of discharge member, those ducts 73 which terminate at the lower levels are of less length than the other 45 ducts and hence serve to draw more fuel from the annular discharge orifice 70. By using this arrangement it is not necessary to provide as many ducts for varying the mixture in the higher ranges of motor speeds.

As shown in Fig. 4, two of the horizontal bores 76 formed at different levels on the discharge member may merge or communicate with the same groove 75 so as to increase the suction in the particular groove and thus increase its effec55 tiveness in drawing fuel from the arcuate section of the fuel discharge orifice.

The sliding sleeve 36 is moved up and down by means of a lever 77 mounted within the housing 39 on a shaft 78 which extends through 60 and is journaled in the walls of the housing. The outer end of the lever 77 is connected to the piston 37 by means of a link 79. An arm 80 is secured on the shaft 78 (Fig. 2) outside of the housing 39 for connection to. a suitable G5 foot pedal or manual actuating device (not shown). As will be apparent from Fig. 1, the lever 77 will be in a substantially vertical position when the sliding sleeve 36 is in its upper or idling position and when the manual operat70 ing device (not shown) is moved at a given rate, the sliding sleeve 36 will be moved downwardly at a comparatively slow rate at first since the vertical component of a given arcuate movement of the arm 77 will be small when the arm is near 75 its vertical position. As the sleeve 36 approaches its open position its rate of movement will increase materially relatively to the rate of movement of the manual actuating device since the arm 77 will then be near its horizontal position as shown in Fig. 1 and the vertical component of a given i arcuate movement will be comparatively large.

Thus this actuating mechanism enables the operator to control more accurately the fuel mixture and the resulting acceleration of the motor in its lower range of speeds. An adjustable stop i device in the form of the bolt 81 is positioned in the wall of the housing 39 to engage the lever 77 and limit the upward movement or idling position of the sliding sleeve 36.

A similar operating device is provided for the sliding choke sleeve 47, this operating device comprising a lever 82 mounted on a horizontal shaft 83 extending through and journaled in the air intake 12 and having an operating lever 84 on its outer end which may be connected to a suitable operating- wire 85. The outer end of the lever 82 is connected to the sliding choke sleeve by a link 86 and the upward movement of the sleeve 47 is limited by an adjustable stop 87 mounted in the body 10 in the path of the upper 1 end of the link 86.

In order that the sliding throttle sleeve 36 may be more accurately and easily controlled by the operator, means is provided for counteracting the tendency of the sliding sleeve 36 to 1 be moved upwardly by the action of the motor suction. This means preferably includes the piston 37 and the cylinder 38 which support and guide the sliding sleeve 36. A passage 89 formed in the body 10 extends from the cylinder 38 up- ] wardly through the body and opens into the tubular portion 14 which forms the outlet opening of the carburetor, a longitudinal slot 90 being formed in the choke sleeve 47 so that in all positions of the sleeve 47 the cylinder 38 communi- : cates with the same suction source that tends to move the sliding sleeve 36 upwardly. Thus by properly proportioning the size of the piston 37 H and the cylinder 38 an equalizing force is applied H to the moving parts so that the operator may B more easily and accurately control the movement H of these parts. H

In the operation of the carburetor on a motor, M the motor is provided with a rich starting mix- M ture by lowering the choke sleeve 47 by means M of its operating lever so that when the sliding M sleeve or throttle 36 is lowered, (Fig. 6) the sec- ondary air passage through the venturi 46 will remain closed. With the sliding throttle sleeve 36 in its lowered position and the secondary air cut off, the motor is turned over by the starter to draw air through the venturi 45. The throat 50 of the venturi being then positioned beneath certain of the ducts 73, those ducts will function as fuel passages to draw fuel from the annular orifice 70. At the same time air will be drawn into the annular passage 71 through the openings 72 and upwardly past substantially the entire length of one side of the orifice 70 to draw fuel into the mixing chamber 74 where it will be well mixed with the air to provide a rich fuel mixture which is discharged into the venturi 45 through the ducts 73. In the venturi 45 the mixture is made slightly more “lean” by the primary air passing therethrough and is then passed from the outlet 14 to the motor.

When the motor has been started and warmed up by the rich fuel mixture thus provided, the choke sleeve 47 and the sliding throttle sleeve 36 may be raised to their normal or idling position

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Shown in fig. 2 wherein most of the ducts 73 lie below the Venturi throat 50 and are therefore ineffective as fuel discharge passages. While the parts are in this idling position, fuel in smaller . 5 quantities is drawn into the mixing chamber 74 through a few small arcuate sections of the orifice 70 and . is there mixed with air in substantially the same manner as when the carburetor is choked, the ducts 73 opening above the 10 Venturi throat 50 being the only ones which act as fuel discharge passages. The other ducts 73 lying beneath the Venturi throat 50 may then supply air to the mixing chamber 74 in a manner similar to the operation of the openings 72 at 15 other times.

When it is desired to accelerate the motor, the sliding sleeve 36 is moved gradually downwardly to position the Venturi throat beneath the ducts 73 in gradually increasing numbers so as 20 to bring them into play as fuel discharge passages and cause fuel to be drawn through a greater number of small arcuate portions of the orifice 70. During this movement the inner venturi 45 is opened to permit passage of a larger 25 amount of primary air, and the outer venturi 46 is opened to permit the passage of secohdary , air. ·,·'.

As the ducts 73 are brought into active play as fuel discharge passages the mixing chamber 30 74 continues to function in the same manner as it did while the motor was idling, this condition being changed only at the very highest motor speeds wherein the sliding'sleeve 36 is positioned so that the openings 72 are above 35 the Venturi throat 50. When this condition obtains, these openings will also serve as fuel discharge passages due to the great suction applied thereto by the motor. . _:

If it is desired to reduce the amount of sec40 ondary air admitted, the adjusting stop 87 may be screwed inwardly to change the normal position of the sleeve 47 and thus reduce the size of the venturi 46.

During the operation of the carburetor, the 45 equalizing means renders the throttle sleeve 36 more easily movable sq that the motor may be accelerated very smoothly. The use of the crank 77 as a throttle operating means also serves to facilitate the gradual and accurate 50 movement of the throttle sleeve 36 to provide for more gradual acceleration of the motor in its lower ranges of speed.

From the foregoing it will be apparent that the invention provides a carburetor which may 55 be economically manufactured since it is formed ^rom a comparatively small number of parts which may easily be assembled. It will also be seen that the carburetor wifi be efficient in operation by reason of the simplicity and accuracy 60 of the adjustments provided for varying the fuel mixture and also by reason of the accurate throttle control provided by the actuating connection which embodies a crank.

It will also be evident that the carburetor is 65 of such a construction that the parts may be easily designed and constructed to provide a combustible mixture which varies in richness in accordance with a predetermined standard determined by the size and type of motor with 70 which it is to be used. The carburetor herein disclosed also makes it possible to obtain a more gradual and smooth acceleration of the motor, since it operates on the same principle when it is choked, when it is idling, and when it is being ?5 accelerated through the lower ranges of speed.

The means provided for equalizing the forces exerted on the throttle sleeve renders the thrnttte sleeve more easily and accurately controllable and thus make it possible more smoothly to accelerate the motor. _β