US3038706A - Carburetor construction - Google Patents

Description

June 12, 1962 v T. M. BALL 3,038,706

CARBURETOR CONSTRUCTION Y Filed June 4, 1959 3 'Sheets-Sheet 1 INVENTOR. 7g j Tfra/af MEQ/.

5g #wwwa/4f N12/UVW June 12, 1962 Filed June 4, 1959 T. M. BALL CARBURETOR'CONSTRUCTION s sheets-sheet 2 Il C?? ff jNVENToR. I7'0/11d5 M54' ZZ BY l Il June12,1962 T. MBALL 3,038,706

CARBURETOR CONSTRUCTION Filed June 11V 1959 5 Sheets-Skizze?I 3 20 .J2 IN V EN TOR.

Y ALW wm I lnite This application relates to improvements in a carburetor for an internal combustion engine.

The demands of modern automobile styling to -lower the vehicle body `and engine hood, together with the advent of the V-8 engine which cannot -feasibly use an updraft type carburetor, have caused considerable attention to be given to the provision of new means for supplying engine fuel in order to avoid the high silhouette of the conventional carburetor. Although the modern carburetor has been compacted and its overall height has been materially reduced, it is still too high Ifor styling demands. Various types of fuel injection systems have been proposed to supplant the carburetor, but the cost of such systems has prevented their acceptance except in the more expensive automobiles.

An important object of the present invention is to provide an improved low silhouette carburetor which satisfies the requirements of modern styling and enables a lowered engine hood without recourse to a fuel injection system.

Another and more specic object is to provide such a carburetor wherein the air horn and venturi of the usual inlet air induction system comprise a single elbow-shaped tubular conduit wherein the throat of the venturi is downstream of the elbow bend in the conduit and the .air horn is upstream of the bend.

Another object is to provide an improved carburetor structure of the above character wherein the customary secondary or small venturi mounted to discharge into the throat of the first-named venturi has its inlet and discharge openings at opposite sides of the transverse plane through the line f the interior angle of the elbow bend formed by the upstream air horn portion of the inlet conduit.

Still another object is to provide an improved carburetor which is particularly simple and economical to fabricate and assemble and wherein the elbow shaped inlet conduit7 together with other portions of the carburetor body, are readily susceptible of economical manufacture by ordinary die-casting operations.

Other and more specific objects are to provide such a carburetor wherein the venturi portion and a proximate segment of the air horn defining the interior angle of the elbow bend comprise one integral die-cast section, a segment of the air horn cooperable with the first-named segment to complete the tubular air horn comprising another die cast section; and wherein a major portion of the fuel bowl at least up to the fuel level comprises an integral part of the first-named section, the fuel bowl cover comprising an integral part of the second-named section.

The short compact design of the elbow-shaped air inlet conduit is illustrated in the drawings by way of example for use with a dual downdraft type carburetor, although it will be apparent from the following description that the inlet conduit shown could be used with either a horizontal or updraft carburetor of other than the dual type. When the compact design as disclosed is employed with the dual carburetor shown, the portion of the inlet conduit that is ordinarily divided into two parts is relatively short and some of the advantages of the dual over the single carburetor are reduced in importance in various engine constructions.

In order to minimize loss of effectiveness of the customary dual carburetor, it is another object of the inven- States Patent tion to provide means for partitioning the inlet conduit into two parts upstream of the venturi throat and to extend the partition beyond the customary choke blade in the air horn where required.

Another object is to provide an elbow-shaped air inlet conduit of the above character wherein curved baffles including a curved choke valve blade are provided adjacent the elbow bend to direct inlet air around said bend and to provide for a more uniform air flow distribution in the inlet conduit downstream of the bend.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIGURE l is a horizontal sectional view through a carburetor construction embodying the present invention, taken in the `direction of the arrows substantially along the line 1-1 of FIGURE 2.

FIGURE lA is a fragmentary enlarged vertical sectional view taken in the direction of the arrows substantially along the line 1A-1A of FIGURE l.

FIGURE 2 is a fragmentary vertical sectional View taken in the direction of the arrows substantially along the line 2 2 of FIGURE l.

FIGURE 3 is a fragmentary end view of the air horn taken from the left end of FIGURE 2.

FIGURE 4 is a fragmentary horizontal sectional view similar to FIGURE l, but taken in the direction of the arrows substantially along the line 4 4 of FIGURE 5 and showing a modified construction.

FIGURE 5 is a fragmentary elevational view of FIG- URE 4 with portions broken away to show details of the choke blade structure. Y

FIGURE 6 is a -view similar to FIGURE 5 showing another modified construction.

FIGURE 7 is a Ifragmentary horizontal sectional view taken in the direction of the arrows substantially along the line 7-7 of FIGURE 6.

FIGURE 8 is a view similar to FIGURE 7, but taken in the direction of the arrows substantially along the line 8-8 of FIGURE l0 and showing still another modification.

FIGURE 9 is a fragmentary elevational view of the left end of FIGURE 8.

FIGURE l() is a fragmentary vertical sectional view taken in the direction of the arrows substantially along the line 10-10 of FIGURE 8.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring in more particularity to FIGURES 1 3, a carburetor embodying the present invention is illustrated comprising upper and lower die-cast body or housing portions A and B respectively suitably bolted together and to a throttle body 15, for example by a plurality of bolts 16. The lower cast section B includes a fuel bowl 17 spaced from an inlet air induction passage 18 by a wall 19. A fuel inlet fitting 20 is secured to a side wall of the fuel bowl 17 and provides means for attachment with a fuel source for supplying the bowl with fuel. A valve 21 coupled by brackets 2.3 to a pair of floats 22 within opposite sides of the bowl 17 controls the inlet fuel in accordance with customary practice and maintains a desired fuel level within the bowl 17. L0- cated between the floats 22 are the piston and cylinder of a fuel accelerating pump mechanism 24.

A recess 25 formed in the central portion of the wall 19 provides a shelf 26 for a venturi cluster comprising a venturi mounting portion 27 seated on the shelf 26 and a pair of small venturis connected with the mounting portion 27 by integral portions 29, FIGURES 1 and 1A. A suitable gasket 27a is interposed between the shelf 26 and base of the mounting portion 27. Recessed into the wall 19 and mounting portion 27 is a pair of fuel wells 30, each containing a perforated vent or partitioning tube 31 vented at its upper end to the inlet conduit 18 upstream of the small venturis 28. Also extending. into each well 30 adjacent the vent tube 31 is an idle tube 32 opening at its lower end into the well 30. The tubes 31 and 32 are suitably secured to the mounting portion 27 to be removable therewith. Exteriorly of each well 30 and extending in the wall 19 is an idle fuel conduit 33 which communicates with a continuation 34 thereof formed in the throttle body 15 and opens at an idle fuel orifice 35 into one of each of a pair of downstream portions 36 of the passage 18. A separate suitable idle adjusting needle valve 37 controls the extent of opening of each orifice 35 and is adjusted by screw 38 maintained in adjusted position by spring 39.

A pair of tubular idle vent screws 41 vented at their upper ends to an upstream portion of the induction conduit 18 above the venturis 28 are screwed into the wall 19, each being coaxial with one of each of the idle ducts 33 to comprise an upper continuation of the latter. An annular recess 42 in the outer portion of the upper end of each screw 41 communicates with the bore of the latter tube via transverse ducts 43 and also with the upper end of the associated idle tube 32 via duct 44, thereby to complete a pair of idle fuel conduit systems, each extending from the bottom of the associated well 30, tube 32, ducts 44 and 43, tube 41 and conduits 33 and 34 to the corresponding orifice 35.

A primary fuel inlet conduit 45 extends through the base of wall 19 into each well 30 and is closed at its right end in FIGURE 1A by a plug 46. A separate tubular metering jet 47 having its bore in communication with one of each of ducts 45 is screwed into the base of the fuel bowl 17. The upper portion of each metering jet 47 comprises a guide and the lower portion is provided with transverse ducts 48` opening into the fuel bowl 17 to provide communication between the latter and associated duct 45. Shiftable vertically within the upper guide portion of each jet structure 47 is a Wire plunger 49, which preferably comprises a straight length of piano wire, having its upper end secured to the cross arm 50 of a plunger 51. The latter is actuated by a piston within a cylinder 52 which is operably connected with the engine intake manifold pressure so as to raise cross arm 50 and the two wires 49 to allow increased fuel flow through the lower ends of the metering tubes 47 into the supply ducts 45 upon an increase in engine load. Conversely, as engine load decreases, the wires 49 are lowered to progressively restrict the lower ends of tubes 47 from their ducts 45.

From each fuel well 30, which is supplied by its separate duct 45, fuel is conducted during operation of the engine to one of each of a pair of main fuel supply nozzles 53, one discharging into one of each of the small venturis 28. The lower end of each small venturi 28 opens coaxially into the throat of one of each of a pair of larger primary venturis 54 located immediately above the throttle body 15 and discharging coaxially into a separate induction conduit portion 36 which communicates with certain of the engine cylinders.

In the dual type of carburetor shown, two large venturis 54 are provided side-by-side in the inlet conduit 18, each discharging into a separate downstream conduit portion 36. Thus during operation of the engine under load, the inlet air flow through the venturis 28 draws fuel from the wells 30 through the nozzles 53. The upper openings of vent tubes 31 to the induction conduit 18 upstream of the venturis 28 results in a downward air ow through the vent tubes 31 and thence out the number of longitudinally spaced openings therein into the respective well 30, thereby to aerate the fuel within the wells 30 and lower the effective fuel head therein, thereby to facilitate fuel flow up to and out of nozzle 53. The structure described thus far may be conventional if desired and is accordingly not described in further detail. Reference may be had to applicants Patent Number 2,966,344 for a more. detailed explanation of the carburetor structure illustrated.

Immediately upstream of the two large venturis 54, the inlet conduit portions 36 merge into the single conduit 18 which turns sharply at an interior angle 55, FIGURE 2, and provides a lower segment 56 of an elbow-type air horn integral with the venturis 54 and fuel bowl 17. As illustrated in FIGURE 3, the lower air horn segment 56 is channel-shaped in its vertical transverse section and opens upwardly.

The die cast section A comprises a cover 57, see also FIGURES 4 and 5, for the fuel bowl `17 and an integral fiange 58 which depends from the cover 57 toward wall 19 to effect separation between the interior of the fuel bow-l 17 and the induction conduit 18, FIGURE lA. A gasket 59 is preferably employed between the fuel bowl 17 and its cover 57 to effect a leak-proof seal. Integral with the cover 57 is an upper air horn segment 68 which cooperates with the lower segment 56 to complete the tubular ai-r horn indicated. Where desired, the gasket 59 is extended the length of the air horn at the juncture between tlle segments 56 and 68. In this regard, it is to be noted that the line of juncture between the two air horn segments is coplanar with the juncture between the fuel bowl 17 and its cover 57 and is preferably above the normal fuel level in bowl 17. The left end or mouth of the air horn is flared at 61 and is provided with a plurality of reinforcing webs 62 for attachment with a conventional air filter.

Extending in the vertical mid-plane of the air horn from the upper and lower Vsegments 60 and 56 respectively are septums 63 and 64 which meet at a tongue and groove juncture 65 approximately at the level of the gasket 59. The lower septum 64 extends to the top of a septum 66 which denes the body of cast section B and separates the two venturis 54. The air horn segments 56 and 60 are provided with lateral flats 67 adjacent their juncture and with upper and lower ats 68 to facilitate mounting aud operation of a choke blade 69. The latter is mounted in unbalanced position on a pivotal shaft 70, FIGURE l, which extends transversely through the flats 67 in the lower segment 56 and is journalled at opposite sides of the blade 69 in external reinforcing bosses 71 integral with the segment 56. In order to enable free pivotal movement of the blade 69, a recess 72 is provided in septum 64 for shaft 7 0 and oppositely directed notches 73 are provided in blade 69 at opposite sides of its pivot axis. The blade 69 is secured to a attened portion of shaft 76 by screws 74 and is operated manually or automatically in accordance with conventional practice.

FIGURES 4 and 5 illustrate a structure similar to that in FIGURES l3, but the throttle body is formed integrally with the cast section B. In FIGURE 5, a throttle blade operating lever 75 is adapted to be connected at 76 to a throttle operating linkage and is secured at its lower end to an extension of throttle Ablade shaft 77 to rotate the latter. The shaft 77 extends transversely across the two induction passages 36 to provide a common support for two throttle blades 78 secured 4to shaft 77 by screws 79 within the openings 36 respectively, FIGURE 2. A horizontal connecting link 80 is pivotally connected at opposite ends to the throttle lever 75 and to a second lever 81 which is keyed to 'a shaft 82 to pivot the latter upon operation of the throttle lever 75. The shaft 82 is pivoted on the cast section B and is connected by means not shown to the accelerator pump mechanism 24 in order to supply a charge of accelerating fuel to the engine in accordance with customary practice upon each rapid actuation of the throttle lever 75.

Also as illustrated in FIGURE 5, the septums 63 and 64 are provided with circular openings 83 Iand 84 which cooperate to provide a complete circular openi-ng for a `circular partitioning disc 85 mounted on choke shaft 70.- The disc 85 completely lls the circul-ar opening made by the recesses 83 and 84 and cooperates with the septums 63 and 64 to provide a separation between the two 4halves of the -air horn as in FIGURES 1-3, regardless of pivoting of the throttle blade 69a. In this instance, instead of the unbalanced choke blade 69, a balanced circular choke bl-ade 69a is secured to shaft 70 by screws 74 and is particularly adapted for use in installations where a manual choke is employed. In other respects, the structure and operation of the carburetors illustr-ated in FIGURES l-S are the sa-rne, so that corresponding parts are numbered the same in each view.

The septums 63 and 64 shown in FIGURES 1 5 separate the air horn into two halves completely from its mouth or upstream opening to the customary partition 66 between the two large venturis 54. It has been found that such a partition is import-ant forY optimum power and fuel economy with certain engine types employing the compact or shortened elbow-type inlet conduit 18. It is customary in the use of dual carburetors to discharge admixed fuel and air to the engine alternately from the two venturis 54 with al-ternate linings of the engine cylinders, thereby to minimize interference with the fuel-air llow. A pressure kick-back or impulse through the side of the inlet induction conduit in communication with the cylinder that is tiring tends to interfere wit-h the inlet fuel-air flow in the other side of the induction conduit unless an adequate length of partition is provided in the air horn upstream of the venturis 54. The length of the partition depends upon numerous factors including the size of, the engine, the overall cross sectional area and length of the inlet induction conduit to the engine, and the valve timing, so that with some engine types a shorter parti-tion as illustrated in FIGURES 6 .and 7 can ybe satisfactorily employed.

In the latter ligures, the upstream edges of the septums 63 and 64 terminate at 63b and 64b respectively just downstream of the choke shaft 70. In this instance, wherein the choke shaft '70 extends through the lower segment 56, the lower septum 64 is notched at 86 to provide adequate clearance for the shaft 70. Also the choke blade 6%, comparable to the blade 69, is notched at '13b in order to provide clearance for the septums 63 and 64 upon pivoting of blade 69,5. In other respects, the structure and operation of the carburetor ilustrated in FIG- URES 6 and 7 and the same as described above in regard to FIGURES l-5, so that corresponding parts are numbered the sante in all views.

FIGURES 8-10 illustrate an even shorter air horn partition wherein the upstream edges of the septums 63 and 64 terminate at 63C and 64C respectively, FIGURE l0, immediately downstream of the innermost projection o f the choke blade 69C when the latter is in the open position. In' this instance the upstream or leading edges 63C and 64C cooperate to provide a partition which declines from the top to the bottom of the air horn in the upstream direction. Thus the uppermost portion of the leading edge of the .septum 63y is downstream of the choke blade 69e and the lowermost portion of the septum 64 extends to a position upstream of the choke blade when the latter is in its wide open position. By this structure a compromise partition length is achieved without necessitating a notch-ed choke blade.

Also as illustrated in FIGURE l0, the downstream edge of choke blade 69C curves downwardly to effect a baille action which assists the direction of the inlet air llow around the bend of the air horn when the choke blade 69C is at its open position. Conforming substantially to the upper curvature 55C of the elbow bend, a fixed baille 87 extends transversely across the upper portion of induction chamber 18 at a location between the trailing curved edge of blade 69c and said upper curvature 55C. As illustrated in FIGURES 8 and l0, the opposite lateral edges of the curved baille 87 are provided with integral projections 88 confined within a pair of parallel supporting slots S9 formed at opposite sides of the upper air horn segment 6G. The slots 89 decline in a downstream direction and open at the lower edge of the segment 60. Prior to assembly of the segments 60 and 56, the projections 88 of braille 87 are inserted into the lower ends of the slots 89, whereupon after assembly of the segments 56 and 68', the lowermost of the lateral projections 88 will rest upon the upper edges of segment 56 and hold the baille 87 in position. The trailing edge of baille 87 is slotted centrally at 90 in order to receive the lower septum 64. The baille 87 with its integral projections 88 can be feasibly stamped from sheet metal, the projections 88! being twisted angularly with respect to the curvature of the baille so as to fit snugly within the opposed straight slots 89.

The curved baille 87 or curved'chotke blade 69C can be employed in `any of the above-described structures and are particularly useful with certain engine installations for assisting the necessary change of direction of air flow around the bend of the inlet conduit l8r.

I claim:

l. In a carburetor construction for an internal conibustion engine having `air induction conduit means, an elbow-shaped tubular inlet conduit for said carburetoi having a venturi portion adapted for communication With said induction conduit means to discharge thereinto downstream of the bend in the elbow of said inlet conduit and having an air horn portion adapted for communication with an inlet air supply upstream of said bend, said inlet conduit comprising two cast sections, one of said sections including said venturi portion, said one section comprising the interior angle of said bend and a segment of said air horn portion extending longitudinally of the latter, the upstream end of said venturi portion flaring endwise and comprising a rounded interior surface Iat the bend of said elbow merging with said longitudinally extending air horn segment, the other section including a segment of said air horn portion cooperating with the first named segment to complete a tubular air horn.

2. In a carburetor construction for an internal combustion engine having a down-draft air induction conduit means, an elbow-shaped tubular inlet conduit for said carburetor having a downstream venturi portion below the bend of the elbow and adapted for communication with said induction conduit means to discharge thereinto, said inlet conduit also having an upstream air horn porton above said bend and adapted for communication withV an inlet air supply, said inlet conduit comprising tw'o cast sect-ions, one of said sections including said venturi portion, said one section comprising the interior angle of said bend and a segment of said air horn portion extending longitudinally of the latter, the bottom of the interior of said segment being level with the top of said venturi port-ion and merging thereinto at a rounded surface comprising a flared upper end of said venturi portion, the other section including a segment of said air horn portion cooperating with the first named segment to complete a tubular air horn.

3. In a carburetor construction, a throttle body having a down-draft induction conduit portion therein, an air inlet conduit secured to said throttle body comprising an elbow having a downstream venturi portion in communication with said conduit portion to discharge thereinto and also having an upstream tair horn portion extending transversely of said venturi portion, said inlet conduit cornprising two sections, one of said sections being proximate and above said throttle body and including the interior angle of said elbow and a segment of said air horn opening in the direction axially of said induction conduit portion and upwardly from said throttle body, the bottom of the interior of said segment being `level with the top of said venturi portion and merging thereinto at a rounded surface comprising a flared upper end cf said venturi portion, the other section including .a segment of said air horn opening in the opposite direction, said segments cooperating to complete a tubular air horn, said one section also including a fuel bowl, and said other section also including a fuel bowl cover, said segments extending longitudinally of said `air horn and meeting adjacent the plane of the interior surface of said fuel bowl cover.

4. In 4a carburetor for an internal combustion engine having air induction conduit means, a tubular elbowshaped air inlet conduit for said carburetor having a pair of venturi throat portions arranged therein side-by-side downstream of the elbow bend for communicating with said induction conduit means, said venturi throat portions being on opposite sides of the mid-plane of said inlet conduit containing said bend, said inlet conduit having an air horn portion upstream of said bend for communicating with an air supply, said inlet conduit comprising two cast sections, one of said sections including said throat portions, said one section comprising the interior angle of said bend and a segment of said air horn portion extending longitudinally of the latter and defining said interior angle, the other section of said inlet conduit including a segment of said air horn portion cooperating with the first named segment to complete a tubular air horn, each section having an integral septum parallel to and adjacent said mid-plane, the two septums cooperating to partition said air horn into ltwo parts upstream of said venturi throat portions, each part communicating with one of each of said venturi throat portions, a choke valve blade in said air horn having a pivot axis extending transversely of said septums, said septums extending both upstream and downstream of said blade and being recessed to provide an opening conforming to the arc scribed by said blade upon pivoting thereof, and a partition element pivotal with said blade arranged within said opening to fill the same and comprise a continuation of the partition effected by said cooperating septums.

5. In a carburetor for an internal combustion engine having air induction conduit means, a tubular elbowshaped air inlet conduit for said carburetor having a pair of venturi throat portions arranged therein side-by-side downstream of the elbow bend for communicating with said induction conduit means, said venturi throat portions being on opposite sides of the mid-plane of said inlet conduit containing said bend, said inlet conduit having an air horn portion upstream of said bend for communicating with an air supply, said inlet conduit comprising two cast sections, one of said sections including said throat portions, said one section comprising the interior angle of said bend and a segment of said air horn portion extending longitudinally of the latter and defining said interior angle, the other section of said inlet conduit including a segment of said air horn portion cooperating with the first named segment to complete a tubular air horn, each section having an integral septum parallel to and adjacent said mid-plane, the two septums cooperating to partition said air horn into two parts upstream of said venturi throat portions, each part communicating with one of each of said venturi throat portions, and a choke valve blade in said air horn having a pivot axis transverse to said septums, said blade having a curved downstream portion effective in the open position to deflect incoming air around said bend.

6. In a carburetor for an internal combustion engine having air induction conduit means, a tubular elbowshaped air inlet conduit for said carburetor having a pair of venturi throat portions arranged therein side-by-side downstream of its elbow bend for communicating with said induction conduit means, said inlet conduit having an air horn portion upstream of said bend for communieating with an air supply, said inlet conduit comprising two sections, one of said sections including said throat portions, said one section comprising the interior angle of said bend and a segment of said air horn portion extending longitudinally of the latter and defining said interior angle, the other section of said inlet conduit including a segment of said air horn portion cooperating with the first named segment to complete a tubular air horn, and a choke valve blade in said air horn having a pivot axis transverse to said air horn, said blade in the open position having a curved downstream portion extending into the region of curvature of incoming air around said bend and being effective to deliect said incoming air around said bend.

7. In a carburetor for an internal combustion engine having a down-draft air induction conduit means, a body casting for said carburetor comprising a fuel bowl and a tubular elbow-shaped air inlet conduit, said inlet conduit having a venturi arranged therein below and downstream of its elbow bend for communicating with said induction conduit means and also having an air horn portion above and upstream of said bend for communicating with an air supply and extending transversely of said venturi, said casting comprising one section including said venturi throat portions, a segment of said air horn portion extending longitudinally of the latter and defining the interior angle of said bend, and a portion of said fuel bowl proximate said air induction conduit means, the bottom of the interior of said segment being level with the top of said venturi and merging therewith at a rounded surface comprising the enlarged upper end of said venturi, said casting comprising another section including a segment of said air horn portion cooperating with the first-named segment to complete a tubular air horn and also including a cover for said fuel bowl, a separate secondary venturi mounted in said venturi and having its inlet and outlet openings located respectively above and below said bottom of said first-named segment, and a fuel feed nozzle in communication with said fuel bowl and discharging into said secondary venturi.

8. In a carburetor for an internal combustion engine having an air induction conduit means, a tubular elbowshaped air inlet conduit for said carburetor having a pair of Venturi throat portions arranged therein side-by-side downstream of the elbow bend for communicating with said induction conduit means, said venturi throat portions being on opposite sides of the mid-plane of said inlet conduit containing said bend, said inlet conduit having an air horn portion upstream of said bend for communicating with an air supply, said inlet conduit 50 comprising two cast sections, one of said sections including said throat portions, said one section comprising the interior angle of said bend and a segment of said air horn portion extending longitudinally of the latter and defining said interior angle, the other section of said inlet 5 conduit including a segment of said air horn portion cooperating with the first named segment to complete a tubular air horn, a partition separating said air horn into two parts upstream of said venturi throat portions, each part communicating with one of each of said venturi throat portions, a choke valve blade in said air horn having a pivot axis extending transversely of said partition the latter being recessed to provide an opening conforming to the arc scribed by said blade upon pivoting thereof, and a partition element pivotal with said blade arranged within said opening to fill the same and comprise a continuation of said partition.

9. In a carburetor for an internal combustion engine having air induction conduit means, an air inlet conduit o for said carburetor having a pair of venturi throat portions arranged therein side-by-side for communicating with said induction conduit means, said inlet conduit having an air horn portion for communicating with an air supply, a partition separating said air horn into two 75 parts upstream of said venturi throat portions, each part communicating with one of each of said venturi throat portions, a choke valve blade in said air horn having a pivot axis extending transversely of said partition, the latter being recessed to provide an opening conforming to the are scribed by said blade upon pivoting thereof, and a partition element pivotal with said 'blade arranged within said opening to ll the same and comprise a con tinuation of said partition.

References Cited in the le of this patent UNITED STATES PATENTS Johnson Apr. 19, 1932 Mock et a1 Oct. 31, 1933 Johnson Nov. 7, 1933 Mock Mar. 27, 1945 Ericson Oct. 9, 1945 Winkler Apr. 1, 1958

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