US1983255A - Carburetor - Google Patents

Description

Dec. 4, 1934. G, A. WAHLMARK CARBURE'IOR 2 Sheets-Sheet l Filed May 25, 1929 w 4 7 u m J (.3 m 66 53M 3 6 6 @ad fr@ @do 02m/maf Dec. 4, 1934. G. A. WAHLMARK 1,983,255

I CARBURETOR Filed may 25,- 1929 2 sheets-sheet 2 r '30 the 4main'body of 'the carburetor f Patented Dec. 4, t 1934 oNi'rE sra TEST] PAT ENT oiluficr.

cannuna'roa to `(lliax'les H.

Gunnar A. Wahlmark, Rockford, lll., assigner ofi one-third to Ernest J.

Svenson and one-third ltysiom, both of Rockford, Ill.

Application May 25, 1929, Serial (No. 365,869 16 Claims. (Cl..26 14) 'lo to meet the requirementsv oi' 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 y 1'5 performance fully satisfactory.

The attainment of these results with a particular motor is dependent to a great extent upon the thoroughness of the vapor-ization of the fuel as well as upon therichness of the fuel mixture supv 420 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 discharge member so that the mixing of the air and fuel is initiated within this chamber. At the lower-motor speeds, the air is directed past small arcuate section of the fuel discharge orice so that fuel is drawn into theannular chamber and theremixed with the air and ischarged into r further mixing witlrair so as to form' a comparatively 1ean fuel mixture. As the motor speed is increased, .air is directed past a progressively increasing number of other small arcuate sections of the Onlya ,'35 fuel discharge orifice to draw more fuel into the Thus `the mixing of fuel and ying a mixing chamber lwherein mixing of air annular chamber. air continues within the chamber and gradually spreads around the same, at the same time increasing'g'radually in the quantity mixed in each 40 portion of the chamber due to the increase in air velocity. t This provides for 'a progressive expansion or growth o1' the mixingzone as the motor speed is increased so that smoothness of motorv operation is inevitablyattained. 1 Another object of the present invention is to provide a carburetor wherein the liquid fuel is subjected to substantially the same mixing or vaporizing action throughout the range of motor speeds. l

Anotherobject is to provide a carburetor having a plurality of different paths along which air .may pass to draw fuel into thecarburetor together with meansfor directing air along varying' numbers of these paths whereby to increase-or 55, decrease the quantity of liduid fuel supplied.

to carburetors v Another object is to provide a carburetor having a comparatively small'` chamber in which the air and fuel are initially mixed together withmeans to control the supply of fuel and the passage of air through the chamber so that the mixing con- 60 tinues therein and progressively increases or spreads'to different parts of the same chamber as Athe motor speed is increased so as to supply a uniformly increasing quantity of thoroughly mixed fuel to the motor. r

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 con.-A

trolled and brought into operation in varying numbers through the action of the sections of compression' and expansion in` a venturi, this re1- sult being obtained'by mounting the fuel discharge member and the venturi for relative movement longitudinally of the venturi, and arranging the ducts` so as to termina-tegatpoints 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 lthe fuel -30 discharge member and the venturi is controlled by the vnumber of ducts terminating on the expansion side of the Venturi throat, and this fact renders the construction particularly advantaseous since it to control the proportioning of fuel-v and air at the various motor speeds. -Thus if a particular motor operate re efficiently at a given speed when-the .pro ortion of fuel to air is reduced, the ducts may be spaced to give this result.

Another object is to provide a carburetor havand fuel is obtained in the same manner when the carburetor is "chokedf, when its parts are set for idling themot or,.and when parts are being moved vto acceleratethe motor.

'More particularly I aim to providea carburetor having a fuel discharge member, means providing a primary -alr supply arranged initially to mix with the fuel, means providing a secondary o air supply for reducing the richness "of the fuel mixture provided by mixing the fuel with the primary air. and a single control member. or throttle operable positively to govern the relat ve amounts of fuel, primary air'and secondary 105 air, the fuel discharge member having a -plurality oi' supply ducts of varying lengths fed from "a single fuel source and brought into operation f as fuel passages in varying numbers as the supply of primary air is varied bythe control member. 110

permits the designer accurately Y movement of the throttle may be easily and accurately controlled by the operator.

In the lower range of motor speeds it is usually K desirable to provide for an exceedingly gradual acceleration. 'Ihe throttle or control member.

of the carburetor is usually actuated by the operator 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 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: f

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.

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 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.

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 in the fuel discharge member'.

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 preferred embodiment of the invention together with one alternative form thereof, it is to be understood that this disclosure' is given for the purposerof illustrating the invention and is not intended as a limitation of the invention to the construction disclosed. In the appended claims, I aimto cover all modifications and alternative constructions falling within the spirit and scope of the invention.

In the form chosen for disclosure herein, the

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 shown) of an internal combustion motor. Thus air may be drawn through the chamber l1 of the carburetor and mixed with fuel in the desired proportion by means contained within the chamber 11 intermediate the intake opening and the outlet o pening.l The voutleto'pening 13 is formed by a vertically extending tubular portion 14 having a ange 15 at its upper end for. Vconnection with the .intake manifold. The air intake 12 is cylindrical in form and extends horizontally in one direction from the bottom of the tubular portion 14. On the opposite sideof 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 byscrews 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 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 21is actuated to maintain a constant level of fuel within thechamber 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 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 structure which may be removed or'adjusted as a unit. To adjust the valve device to maintain different levels of fuel Within the chamber 16 shims `by means cooperating with the discharge mem'- 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 1l 'in surrounding relation to the fuel discharge member 35 for movement along 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 sufcient fuel to run the motor at a low or idling speed.

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 alinement with the tubular portion 14. The lower end of the housing 39 is closed by a plate 39E. 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. 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. p

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 through which air may be drawn by the engine suction. Since this air passes directly by thefuel 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 formedwithin an annular projectingipory tion 48 so that when the sleeve is in its open or 1ower position or in partially open position, a second annular Venturi passage 46 (Fig. l) 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 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 inl Fig. l to the position shown in Fig. 6 to prevent opening of the venturi 46 by downward movement as a choke to cut olf 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 Adischarge member 35.

'Ihe fuel discharge member 35 is circular in horizontal cross section and is of greater 'diame-4 ter at substantially the midpoint of its height.` so

diamond shaped. vThe member is mounted in the chamber 11 so thatl when the sliding sleeve 36 is in its uppermost position as shown in Fig. 2, the portion 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 Vlargest 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 oat chamber 16 is connected with the fuel discharge member 35 by means of a passage comprising a bore 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. The adjusting lever 60 has a spring-pressed detent 61 (Fig. 2) thereon 63 so that the fuel supply may be regulated.

outer diameter of the annular portion 43 so thatV of the sliding sleeve 36. Thus the sleeve 47 serves that in verticalcross section it is substantially' causes airjto be drawn through the duct. sleeve 36 up and down, the

engaging notches 62 formed on an arcuate scale` As illustrated in the drawings, the cross bar 41 has a stem 65, the lower portion of which is threadedto 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 ared outwardly at its upper end and the stem is of such a height that the fuel level (Fig. 1) maintained by the oat 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 Astern soas 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 passage71 (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 they passage 71. The air admitted throughthe openings 72 may pass upwardly about the upper edge of the stem 65, and a plurality of ducts 73 lextending 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 passes through the openings 72 and past the upper end of the stem 65 fuel is drawn from the annular orice 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 stem 65 serves as a mixing chamber for the fuel vAs 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 oriflce 70 suction is applied to the 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 mixture 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 of the ducts 73 are spaced longitudinallyof the axis of the venturi. Thus when the outer end of oneA 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 a pressure which is less than the pressure within the chamber 70 since that chamber communicate". with the compression side of the venturi. This moving the Venturi number of ducts 73 terminating above the throat 50 may be varied with a resulting variation in the amount of fuel drawnv into the mixing lchamber 70.

To provide for an idling mixture, one or more of the ducts 73 mayterminate above the point of greatest diameter of the discharge member 35 so that the slight amount of air passing through the venturi A45 when the sleeve is in its idling position vi se..

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 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 sleeve 36 is in its upper or idling position so that its throat 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 sleeve 36 is moved downwardly, the number 0I' 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 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 0f simplifying the manufacture of the discharge member 35 the plug 68 may be formed with a plurality of longitudinal grooves 75 therein as shown i'gs. 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 73a which are similar to the ducts 73 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 tt'he axis of the vertical bore 67. These bores 76 are formed at different 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 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 the higher ranges of motor speeds. v

A 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 effectiveness 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 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) outsidel of the housing 39 for connection to. a suitable 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 operating device (not shown) is moved at a given rate, the sliding sleeve 36 will be moved downwardly at a comparatively slow rate at rst since the vertical component of a given arcuate movement of the arm 77 will be small when the arm is near 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 willthen be near its horizontal position as shown in Fig. 1 and the vertical component of a given 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 device in the form of the bolt 8l 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 cornprising 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. vThe outer end of the lever 82 is connected to the sliding choke sleeve by a link 86 andthe upward movement of the sleeve 47 is limited by an adjustable stop 87 mounted in the body 10 in the path of the upper 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 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 communicates with the same suction source that tends to move the sliding sleeve 36 upwardly. Thus by properlyproportioning the size of the piston 37 and the cylinder 38 an equalizing force is applied to the moving parts so that the operator may more easily and accurately control the movement of these parts.

In the operation of the carburetor on a motor, the motor is provided with a rich starting mixture by lowering the choke sleeve 47 by means of its operating lever so that when the sliding sleeve or throttle 36 is lowered, (Fig. 6) the secondary 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 primaryair passing therethrough and is then passed from the outlet 14 to the motor.

When the motor has been started and warmed up by therich fuel mixture thus provided, the choke sleeve 47 and the sliding throttle sleeve 36 may be raised to their normal or idling position incassa' parts are in this idling position, fuel in smallerv .5 quantities-is drawninto the lmixing chamber 74 oriflce 70 `andisthere mixed with. air in substantially the same manner as when the carburetor is choked, the ducts 73 opening above the Venturi throat 50 being the only oneswhich act as fuel discharge passages. 'Ihe other ducts 73 lying beneath the Venturi throat 50 may then supply air to the mixing chamber 74 in a manner similarto the operation of the openings 72 at `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 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 y70. During this movement the inner venturi 45 is opened to permit passage of a larger amount of primary air, and the outer enturi 46 is opened to permitthe passage of seco ry am l v As the ducts 73v 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, t condition being changed only at the very highest. motor speeds wherein the slidingf sleeve 36 is positioned so that the openings 72 are above the Venturi throat 50. When this condition obtains, these openings will also serve as fuel discharge passages ldue to the thereto by the motor.-

If it is desired to reduce the amount of sec- 40 ondaryair admitted, the adjustingfgstop' 87 may be screwed inwardly to changethe' normal posif vtion of the sleeve ofthe venturi 46.

During the operation of. the carburetor, the

lequalizin'g means renders the throttle sleeve 36 more easily movable" sq that the 'motor may be accelerated vvery smoothly. The use of the crank 77 as a throttle operating means also serves to facilitate the gradual and accurate movement of thethrottle sleeve 36 to provide for more gradual acceleration'of the motor in' its lower ranges of speed.

From the foregoing it willbe apparent that the invention provides a carburetor which may be economically `manufactured since it is form d from a comparatively small number .of pa s which may easily be assembled. It win also be seen that the carburetor will be efficient in operation by .reason'of the simplicity and -accuracy of the adjustments provided for varying the fuel mixture and also by reason ofthe accurate' throttle controlprovided by the actuating connection which embodies-a crank. It will also be evident that the carburetoris of such a construction that the partsmay bei easily designed and constructed' to provide a combustible mixture which varies in richness in accordance with a predetermined standarddetermined by the size and type of motor with which it is to be used. Thecarburetor herein disclosed also makes it possible to obtain a more gradual and smooth accelerationof the motor, since it operates on thesame principle when it .is choked, when it is idling, and when it is being 7 5 accelerated through the lower rangesv of speed.

through a few small arcuate .sections of the chamber closely adjacent to and annularly great suction applied said orifice and with their outer ends opening Tand thus reduce the size The means provided for equalizingthe forces exerted on the throttle sleeve renders the throttle sleeve more easily and accurately controllable and thus make it possible more smoothly to accelerate the motor. v ,f I claim as my invention: l'. A carburetor having, in combination, a hollow bodyi` having inlet and outlet openings,4 a

`member mounted lwithin said body having a fuel l lsupply duct. with an upwardly' opening narrow annular orifice within the member, there being .an annular fuel mixing chamber in the member and into which said :orice opens, there also p being a plurality of fuel discharge ducts in said member with the 'inner ends opening into said lspabed about said orifice and leading outwardly from saidchamber and opening at different levels and-at peripherally spaced points on the outside of said member, said member being shaped to. form the inner annular side of an annular venturi through which air is drawn during-operation of the carburetor, a sleeve surrounding said member shaped to form the outer side of the venturi, and means for moving one of the Venturi parts to move the throat of theventuri past theends of `salti ducts to cause suction of lfuel from said. ducts when said ducts are at the expansion side of said throat. 4

2. A carburetor having a hollow bodywith inlet and outlet openings, a fuel discharge memberl mounted within said body, said member hav- Ving an annular chamber formedtherein and an annular fuel discharge orifice opening upwardly into said chamber, said member having a'passage through which air ,may passupwardly past one edge of said orifice into said chamber, there .being a pluralityf of ducts in said member with their inner ends opening into said chamber adjacent to/and at annularly spaced points about at different levels onthe outer surface of Asaid member, an annular control member surrounding said discharge member and cooperating to form a Venturipas'sage therebetween, and means to adjust said members relatively to each other to vary the position of the throatof the venturi with respect to the outer `ends of said ducts.

3. In a carburetor, the combination of a hollow body having air inlet and outlet openings, two members mounted in said body forming the inner and outer sides of an annular4 venturi through which air is drawn during operation of the carburetor, a fuel supply, there being a plurality of` fuel discharge ducts formed in one of said members connected. to said fuel suppl" `and opening into said venturi atpoints spaced longitudinally of the venturi, the other of said members being movable to vary the position of the Venturi throat relatively to said ducts so thatl fuel may be drawn through varying numbers of said ducts in accordance with th yposition of the Venturi throat relatively-therzo, said ducts being of different lengths as determined by the amount of fuel which it is desired to draw therethrough.

` 4. In 'a carburetor, the combination of a hollow body hvinginlet and outlet openingaftwo members mounted in said body forming the inner and outer sides of a venturi through which air is drawn during operationof the carburetor, a plurality ofk fuel discharge ducts formed inone of said members and opening into said ventin'i at .points spaced longitudinally of the'venturi, `one of said members being movable to vary the position of the Venturi throat relatively to said ducts 150 thereof, means arranged to discharge fuel into said duct when air is drawn therethrough, said sleeve being longitudinally movable to position the throat thereof intermediate the intake and discharge ends of said duct to cause air to flow therethrough, said sleeve also being movable to a position wherein both ends of said duct are at the same side of said throat so as to prevent flow of air through said duct toward the discharge end thereof.

6. In a carburetor, the combination of a body providing a fuel supply, a primary air passage arranged initially to mix the air passing therethrough with said fuel, and a secondary air pas` sage arranged to mix the air passing therethrough with the fuel mixture formed by the fuel and, primary air, a single annular throttle member operable for controlling the quantity of fuel and primary and secondary air, and a second annular control member arranged to be moved relatively to said throttle member to vary the effect of said throttle member on the secondary air supply for the purpose of providing a rich fuel mixture for starting.

'7. In a carburetor, the combination of a body providing a fuel supply, a primary air passage arranged initially to mix the air passing there- -through with said fuel, and a secondary air passagearranged to mix the air passing therethrough with the fuel mixture formed by the fuel and primary air, a single annular throttle member operable for controlling the quantity of fuel and primary and secondary air, and a second control member operable to cut off or reduce the supply of said secondary air for the purposel of providing a rich fuel mixture for starting.`

..-8. -In a carburetor, the combination of a vfuel discharge member having a chamber formed therein, a first .Venturi member, there being a plurality of ducts in said fuel discharge member leading from said mixing chamber into said Venturi member, said ducts being operable 1A to discharge fuel from said Amixing chamber into said venturi or to admit air lfrom said venturi into said .mixing chamber, and a second Venturi member surrounded by said first Venturi member actuatable to control and vary the number of ducts acting to discharge fuel from the mixing chamber into said venturi.

9. A fuel discharge member for carburetors comprising, in combination, a body having a bore therethrough, a stem extending into the lower endIof said borehaving a vertical passage opening upwardly through which fuel may be con-- ducted into said bore, a plug extending Adownwardly'into the upper end of said bore having a conical lower end extending into said passage to form an annular fuel orifice, s'aid plug cooperating with said stem and the wall of said bore to provide a mixing chamber within the body, said stem being of reduced size near its upper end to provide an annular space between it and'said bore, said body having la pluralityof openings through which air may pass into said space below tudinal grooves formed in the outer surface of said plug and extending upwardly from said mixing chamber and a plurality of bores formed in said body at circumferentially and longitudinally spaced points and communicating at their inner ends with the passages formed by said longitudinal slots.

10,. .A fuel discharge member for carburetors, comprising, in combination, a body of circular horizontal cross-section tapering inwardly from its mid-point toward its top and bottom, said body having a bore therethrough, means extending into the lower' end of said bore through which fuel may be conducted into said bore, a plug extending downwardly into the upper end of said bore and operating with said fuel conducting means and the wall of said bore to provide a mixing chamber within the body, there being aplurality of fuel discharge ducts leading from said chamber to the outside of said body, said ducts being formed by a plurality of longitudinal grooves formed in the outer surface of said plug and extending upwardly from said mixing chamber to form passages closed at their upper ends, and a plurality of substantially horizontal bores formed in said body at circumferentially and longitudinally spaced points each communicating at its inner end with the passage formed by one of said longitudinal slots, the majority of said horizontal bores being formed so as to open onthe inwardly tapered bottom portion of the body.

ll. A fuel discharge member for carburetors, A

end of said bore through which fuel may be con-` ducted into said bor,.a plug extending downwardly into the upper end of said bore and cooperating with said fuel conducting means and the wall of said bore to provide an annular mixing chamber within the body, and a plurality of fuel discharge ducts leading from said chamber to. the outside of said body, said ducts being formed by a plurality of longitudinall grooves formed in the outer surface of said plug and extending upwardly from said mixing chamber and a plurality of bores formed in said body at circumferentially and longitudinally spaced points and communicating at their inner ends with the passages formed by said longitudinal slots.

12. A fuel discharge member for carburetors comprising, in combination, a support, a stem L extending upwardly therefrom having a vertical fuel passage therein, a body having a bore therethrough and mounted with said bore fitting about said stem, a plug lin said bore above said stem having a conical lower end extending into the fuel Apassage in said stem to define an annular fuel discharge orifice within said bore and to provide an annular mixing chamber within the bore above the orifice, openings in said body below said chamber through which air may pass into said chamber, and a plurality of fuel discharge ducts extending from said chamber and opening to the outside of said bodyl at different levels thereon..

13. The combination with a carburetor having a movable throttle member operable to control the speed of a motor and to vary the speed from lo'w to high, of means for actuating said member throughout its range including a crank arm having its outer end connected to said member so that in the lower ranges of motor speeds said end moves substantially transversely of the path of movement of said member while in the upper` ranges lof speed said end moves substantially parallel to said path.

14. A carburetor having, in combination, a hollow body having an air inlet opening in one side thereof and an outlet opening in the top thereof adapted for connection with a motor, a housing formed on said body on the lower side thereof in alinement with said outlet opening, said housing having a cylinder formed therein opening upwardly into said body,.a fuel discharge member supported within said body centrally of said outlet opening and extending across the open end of said cylinder so as to leave an opening on each side of the fuel discharge member, an annular throttle member surrounding said fuel discharge member and cooperating therewith when. in one position to substantially close said outlet opening, and means for supporting and guiding said throttle member for movement toward and away from its closed/position, said means'comprising a piston slidably mounted in said cylinder and a pair of supporting members connected to said piston on opposite sides and extending upwardly on opposite sides of said fuel discharge member and connected to said throttle member. l

15. A carburetor having, in combination, a hollow body having an inlet opening and an outlet opening adapted for connection with a motor, fuel discharge means supported within said body, a manually operable throttle member for closing or varying the effective area of said outlet opening, the suction of the engine tending to move said throttle toward itsidling position, means for supporting andf guiding said throttle member comprising a cylinder in said body, a piston 1n said cylinder upon which piston said throttle member is mounted, and means providing a passage connected at one end to said cylinder on the side opposite from said throttle member and opening at its other end into said outlet 'opening substantially to equalize the suction on said throttle and reduce the effort necessary to open the throttle manually.

16. In a carburetor having a manually movable control member positioned in a suction passage so that the suction tends to move said member toward its idling position, the combination of a piston and cylinder device having one of its parts fixed and the movable part connected to said manual control member, and a connection between said cylinder and the said suction passage on the motor side of said member so that said device applies an equalizing force to said member and permits it to be moved manually with little effort.

GUNNAR A. WAHLMARK.

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