Oct 8, 1946. ' G_. M. BlCKNELL 2,403,726 CARBURETOR ' Original Filed May 7, 1940 2 Sheets-Sheet 2 2,408,726 Patented Oct. 8, 1946 ‘UNITED ‘STATES PATENT OFFICE. Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application November 5, 1942, Serial No. 464,643, which is a division of application Serial No. 333,759, May 7, 1940. Divided and this applica tion September 6, 1943, Serial No. 501,437 ~ ' 6 Claims. (01.261-69) . 1 - , _ This invention relates to carburetors for in~ ternal combustion engines and more particularly to improvements in downdraft carburetors of the tubes 9 and I0,‘Venturi tube 9 b'eingarranged todischarge near the throat of .venturi l3) and venturi- in being arranged to discharge near‘ the constriction 5. plain tube type. . v ’ This application is a division of my application, Serial No. 464,643, ?led November 5, 1942, which is a division of my application, Serial No. 333,759, ?led May‘ '7, 1940 which has now issued as Patent No. 2,328,504. a ’ ‘ The outlet I l of the mixing conduitiscontrolled by a plate-type throttle valve l2 which is rigidly attachedto a throttle'shaft 13 by means of screws I'll; Throttle shaft I3 is journalled in the bosses l5 and 15a. For operation of the throttle valve, a ‘stamped throttle operating .lever i6 is rigidly . . _ ‘ In devices, such as automotive carburetors, 10 attached to one end of the throttle shaft 13. The which utilize a diaphragm for‘ actuating or seal throttle lever. I6 is fabricated from sheet stock ing'a metering valve or other movable part, it by stamping and forming, and is provided at one has been necessary ‘to completely dismantle the end with a perforation I'l toreceive a remote diaphragm in‘ order to inspect or replace the valve control rod (not shown). The throttle lever is 15' or part carried'thereby. ' ' normally urged toward a throttle closing position It is the main object-of the present invention to facilitate applying and removing a valve or other diaphragm operated device which is located behind. the diaphragm. by the usual throttle ‘pull back spring (not shown), whichgenerally forms a part of the re mote control linkage. Lever I6 is also provided with a pairof parallel bent-up portions [8 and . A‘ more detailed'object is to provide means for 20 i9 (Fig.2), which’ are‘ perforated and internally sealingly attaching a metering valve to its actuat screw‘ threaded .to receive a throttle lever adjust ing diaphragm in a manner to permit insertion and withdrawal of the valve through the dia phragm and without the necessity of disassem bling the diaphragm. - ' ~ . ‘ Further objects and advantages of the present invention will be hereinafter set forth in the fol lowing speci?cation and accompanying drawings, in which like numerals ‘indicate identical parts. ing screw. 20. Provision of adjusting screw 2!! permits a ?ne adjustment of the throttle‘ valve when, in a- near closed or idling position. An 25 upper wing lug 2| on body casting l provides a throttle closing limit abutment, and a lower. wing lug 2m provides a throttle opening limit abut ment.- JA- narrow tank 22 formed as part of lever I6 abuts lug 21a as the throttle valve reaches its 30 Figrléis a vertical center section of an automo tiv'e carburetor embodying the invention. The air inlet passage25 is controlled by a plate Fi€.'2is a horizontal section taken on line 2—-2 type choke valve 26 which is eccentrically mount of Fig; 3. ed for rotation with the choker shaft 21 which, open Fig. 3 is a vertical section taken on line 3-3 of Fig. 1. 35 _ Fig. 4 is a vertical section taken on line 4--4 limit.. - . . in turn, is journalled in the bosses 28 and 29. A pair of abutments 26a within the air inlet pas sageway. and castv as an integral part of the air 7 horn} casting ii provide a wide open stop for the 5 is a detailed view of the metering rod choke valve.‘ Referring to'Fig. 3, the left ‘end of and attaching screw. ‘ , ~ choker shaft 21' projects into a casing 30 which 40 'In'the drawings, numeral l indicates a main is cast as anintegral part ofthe airhorn casting ofr‘ig. 1. _ . carburetor body casting having a suitable ?ange 2 formed at the lower end, thereof for attaching 6.‘ The casing 30, together with the cup-shaped tothe constriction or: throat 5. The upper end horizontal bore 83in which is retained a cylin cover 3|. form a housingv which completely? en a carburetor to the intake manifold of an internal A mixing conduit 3 is formed closes'mechanism vfor the automatic control of combustion engine. ' in the main body casting, and an adjacent con 45 the choker valve 26. y , ‘ ' Cast as'an integral part .of the fuel bowl cover ' stant level fuel chamber 4 is cast integral there with, Aportionof the mixing conduit 3 has a ‘l is arcombination fuel inletand vent'boss. 82. Boss 82 is provided with a comparatively large, ventunrorm as indicated at 3a which converges of body casting l is provided with a smooth ?ange surface to whichis attached an air inlet casting drically formed wire screen retainer 84. Fuel. entering through" bore 83 passes through screen 84 and through a horizontal passage 89 ‘to a verticalpassage 90, see Fig.4.v The lower end of or air horn Grand a fuel bqwljcover 1 by means ofv attachingscrews 8. Depending from the air horn casting. 1 and projecting into the upper end 55 passageway.“ is screwthreaded to receive a of the mixing conduitare two concentric Venturi 2,408,726 3 " ' ' " needle seat member 9I, through which is pro vided a bore 92 to admit fuel to the fuel cham ber 4. A conventional float 93 pivoted at 94 acts move metering rod I09 to the left; that, nor mally, the metering rod is urged to the right by Fuel is supplied to the carburetor mixing conduit to the right in a less restricting position in jet 96. spring I25 and that a clockwise rotation of the upon the needle valve 95 in a well known man ner to maintain a constant level of fuel in cham 61 throttle shaft !3 (which is a throttle opening movement) will forcibly. move the metering rod ber 4 substantially as indicated by‘ the line :r—-x. It will also be noted that a movement to the right of diaphragm I I0 caused by a drop in mani for normal and full speed and load operation ‘ of the engine through a metering jet 96, through passages 91 and 98 and is discharged through 10 fold vacuum or throttle opening movement will displace the fuel in chamber “1, causing an in nozzle 99 into the primary Venturi tube 9. Fuel creased pressure‘on jet 96 and also momentarily for low speeds or idling operation is also metered ' raising the fuel level in the constant level cham by jet 96 and passes into passage 9‘! from whence ber. This enriching effect is highly desirable. it passes through the idling jet tube I00 and suit Fuel for acceleration is supplied to the mixing able passages to the usual idling ports adjacent the edge of the throttle when iclosed. ' conduit under pressure by the diaphragm type accelerating device generally indicated at I32, ; The amount of fuel available for aspiration from the main nozzle 99 and the idling ports is varied in accordance with engine intake mani fold vacuum and throttle position by a stepped Figs. 2, 3 and 4, and which comprises a circu lar chamber I 33 formed by a recess in the main body casting and by the recessed cover I34 which ax 20 is attached thereto by means of attaching screws I35. A flexible diaphragm member I36 ?rmly rod clamped at its periphery between cover I34 and net the carburetor body is provided and forms a the partition in chamber I33. The diaphragm I36 rod I09 in accordance with manifold vacuum, a ?exible diaphragm member II 0 is rigidly at 25 is attached at its center to a horizontal plunger I 31 which passes through the cover I 34 and tached to rod I69 at its center by means of the projects therefrom. A spring I38 hearing at plunger member III. Referring to Fig. 3, the one end against a retainer I39 and at its other left hand side of diaphragm III) is subjected to end against cover I34 normally urges the dia intake manifold suction by reason of passages ‘ H2, H3, H4 and H5 which open as a port H5 in 30 phragm I36 and plunger I3‘! toward the right, Fig. 3. which is an intake stroke. A rocker arm the wall of the mixing conduit below the throttle I40 pivoted at one end at MI and having at and/or tapered metering rod I09 extending ially into metering jet 96. As the metering I09, Fig. 3, is moved toward the left, the opening of jet 96 is decreased. To position valve. The recess II ‘I in the carburetor body casting and the generally cup-shaped cover plate I I8 form a working chamber for the diaphragm. The recess I I‘! communicates with the fuel cham ber 4 through a large passage II'I'a, see Figure 2, so that the pocket of fuel therein and the dia phragm are in substantially unrestricted com munication with the remainder of the bowl. The tached at its other end at I50 a spring I 42 which is connected to lever I28 moves the plunger and diaphragm to the left (discharge stroke) as the lever I28 is rotated clockwise (throttle opening direction). 40 ‘provision in lieu of a non-yielding, link results in a smooth yielding pressure being exerted upon the diaphragm and is attached to the body cast The central per foration of cover plate II8. wherein is ?tted for reciprocation the plunger III, is provided with a packing gland I20; The plunger, I II passes through a central perforation in diaphragm H0 and is ?rmly attached thereto by riveting or . stantially stronger than spring I38 and that its cover plate II 8 ?rmly clamps the peripheryaof ing by means of screws H9. I It will be understood that spring I 42 is sub 45 the plunger and diaphragm I36 which is desir able. The accelerating device further comprises inlet passageways I 5| and I52, Figs. 2 and 3, leading from the constant level fuel chamber 4 to the ex pansible chamber I 33. A cylindrically formed wire mesh strainer I53 is provided and is re spinning over the reduc d end of the plunger as tained in passage I52 by the screw threaded inlet > Plunger I I I is further provided with a through 50 check plug I54. The inlet check plug I54 is pro vided with a valve seat I55, a disc check‘valve axial bore of sufficient size to permit the passing I56 and a valve retainer I51. The fuel is dis of the entire metering rod and is provided with charged from chamber I33 through passages I58, internal screw threads I22a at its outer end. An I59, diagonal passage I 60 and an accelerating externally threaded sleeve I22, staked to the rod, as at I23, Fig. 5, is secured in the plunger. It will 55 jet (not shown) into the mixing conduit. A dis charge valve seat is formed at the lower end of be seen from the foregoing that the metering rod passage I59 at I62 by a reduction in diameter. I09 may be removed or assembled without the and a gravity seating ball check valve I63 is pro necessity of removing the cover plate II 8 and vided and adapted to engage seat I 62. The up diaphragm IHJ. Metering .rod I09 is normally urged to the right, Fig. 3, by the lever I24 which 60 per end of passage I59 is screw threaded and re_ ceives a screw plug I64 which is provided with is acted upon by a spring I25. The lever I24 is a downwardly extending stem I65 which limits carried on pivot I26 which also forms a pivot for the upward movement of ball check I63 When the asecond lever I21 which is, in turn, connected same is acted on by discharge pressure. to a lever I 28 by means of a link I29. Lever I26 indicated at I -2 I. A decided advantage gained by the present ar rangement of the accelerating device is that, by extending the discharge passageway upwardly is rigidly attached to the throttle shaft I3. ' Relative motion of levers I24 and I 27 is pre vented in‘ one direction by the ?nger vI3I carried by lever I24. It will be understood that spring I25 is so proportioned and calibrated with re lation to the e?ective area of diaphragm I09 thatthe desired position of the metering rod for a given manifold vacuum is attained. From the foregoing, it will be seen that suf?cient‘ vacuum applied to the left side of the diaphragm IIO will 70 from the very top of the expansible chamber I 33 to a point above the fuel level, pressures..which frequently build up in chamber I33 clue to vapori zation are-released without the forcing of fuel from the chamber as occurs in many construc tions. ' This advantage has particular signi?cance I . due .to the importance of maintaining a full ~ ' charge of fuel in the accelerating chamber. mg, a. lateral. extension below the fuel level and Referring to Fig. l, acomparativelyllarge veri opening’ through the side .wall of said chamber, a diaphragmoclosin'g said opening and acting against the fluid in said chamber, a plate fixed tical passageway IE9 is provided,.extending. from the main fuel passage98 to apoint above the fuel level. The upper part of this passage communi cates with the mixing conduit through a tube I10. This provision has the purpose of relieving vapor pressures at theba'se of nozzle 99,. and its oper ation is fully describedin my copending appli cation, now Patent‘No. 2,234,946, over . and plate opening, andmeans removable through ‘said plate opening and securing said metering pin to said diaphragm whereby movement of said diaphragm by suction regulates theflow of fuel and 92 wherein a substantially constant level as ' '\ and forming . a ' suction axial of the. center of said diaphragm, a. suction inlet passage83, screen 84, and passages 09,50 of the ?oat 93 on needle valve 95. diaphragm passage connecting said conduit and said cham Ioe'r, a metering ori?ce in said main. fuel pas sage, a metering pin for regulating the fuel pass ing? through said ‘ori?ce, said metering pin ex tending axially through said ori?ce,‘ diaphragm, The operation of'the carburetor is astfollow's: Fuel is supplied to the .float chamberA through indicatedby line arr-m is maintained by the action said chamber therewith, said plate having an opening 15 Fuel for normal and high speed operation is supplied to the mixing conduit from fuel chamber through said jet.v ‘4 through metering jet 06, passages 91,.98and nozzle 99. During comparatively light load oper ation, the intake manifold suction will act on. dia phragm I I0 to move. ‘metering rod I00 toward the left, Fig. 3, that is, toward a more restricting position. The position of the metering rod un der these conditions will also be determined by the throttle position. When sufficient load is ap plied to the engine for any given throttle posi . 2. The substanceof claim 1, further including guide structure .for said metering pin in a por tion of the carburetor wallspaced from Isaid , diaphragm. ’ , . ' 3. Ina carburetor, a mixture, conduit,.,afuel bowl forming a constant level ?oat chamber formed on one wall of said conduit, the common wall between said conduit and said chamber being thickened, a main fuel nozzle passage ex tending from the lower part of said bowl through tion to cause a su?icient resulting drop in mani said common wall and opening into said mixture fold vacuum, spring I25 will urge the metering conduit, a fuel nozzle arranged in said nozzle rod toward the right to a less restricting posi passage and extending into said mixing conduit, 3 0 a pocket formed in the wall of the lower part tion. Fuel for idling operation is supplied to the of said float chamber and in open communica mixing conduit from fuel chamber A through jet tion therewith, a suction responsive diaphragm 06, passage 91, idling jet I03, idling tube I00, pas sages l0! and I02, and is discharged into the mix ing conduit near the upward opening edge of throttle valve I2 through the usual idling ports ' forming formed (not shown) . Fuel for acceleration is supplied under pres- , sure to the mixing conduit from the accelerat ing chamber I33 duringv the discharge stroke of diaphragm I35, through passages I58, I59, and I60. The diaphragm I36 is actuated through its discharge stroke by an opening movement of the throttle valve by means of linkage comprising the rocker arm I40, the spring I42, and lever I28. When the throttle is suddenly opened from nearly closed position, pressure in the carburetor outlet and in diaphragm control passages H2 and H3 increases, causing rapid inward move ment of diaphragm IIO by spring I25. This forces liquid fuel back through open bowl com munication I Ila, momentarily raising the level in the bowl, and through main metering jet 90. Ad ditional fuel is thus supplied to the mixture con duit through the main nozzle, both because of the raised level and consequent increased pressure in the bowl and because of the extra charge of fuel forced directly into the main nozzle passage. As the throttle is opened, the distance diaphragm I I0 4. In a carburetor, a mixture conduit, a fuel bowl forming a constant level ?oat chamber formed on one wall of said conduit, the common wall between said conduit and said chamber be ing thickened, a main fuel nozzle passage ex tending from the lower part of said bowl through said common wall and opening into said mixture conduit, a fuel nozzle arranged in said nozzle 50 passage and extending into said mixing conduit, a pocket formed in the wall of the lower part of said ?oat chamber and in open communica tion therewith, a suction responsive diaphragm forming one wall of said pocket, said thickened common wall terminating short of said pocket at 55 can move because of a drop in suction to the car one edge to provide open communication between said pocket and said bowl, a passageway formed in said thickened wall connecting said nozzle pas 60 buretor becomes progressively less, since the dia phragm is impelled inwardly by lever I24 oper ated by the throttle. This is an advantage be cause less auxiliary pick-up fuel is needed for ac celeration from a substantially open throttle posi come within the scope of'the appended claims is contemplated. I claim: I . 1. In a carburetor, a mixture conduit, a main aphragm and extending through and controlling said metering ori?ce, and guide means closely being aligned with said passageway and being 65 positioned inward of said metering ori?ce. The invention is not limited in details to the structure shown, but may be modi?ed in various ‘ respects as will occur to those skilled in the art and the exclusive use of all such modi?cations as sage and said pocket, a metering ori?ce in said passageway, a metering valve secured to said di ?tting a portion of said valve said guide means ‘tionythan from a nearly closed throttle position. fuel passage, a constant level fuel chamber hav one wall of said recess, a passageway in said thickened wall connecting said nozzle passage and said recess, a metering ori?ce in said passageway, a metering valve secured to said diaphragm and extending through and con-l trolling said metering ori?ce, and guide means closely ?tting a portion of said valve, said guide means being aligned with said passageway. 1- 5. In a carburetor, a mixture conduit, a fuel bowl forming a constant level ?oat chamber formed on one wall of said conduit, the common wall between said conduit and said chamber‘ being thickened, a main fuel nozzle passage ex tending from the lower part of said bowl through opening into said mixture conduit, a fuel nozzle arranged in said nozzle passage and extending into said mixing conduit, . said common wall and 75 an opening in an outer wall of said float cham-_ 7 2,408,726 her, a suction responsive diaphragm secured over said opening, a passageway formed in said thick ened wall and connecting said nozzle passage and said ?oat chamber, a metering ori?ce in said passageway, a metering valve secured to said diaphragm and extending through and control ling said metering ori?ce, and guide means closely ?tting a portion of said valve, said guide means being aligned with said passageway and being positioned inward of said metering ori?ce. 6. In a carburetor, a mixture conduit, a fuel bowl forming a constant level ?oat chamber formed on one wall of said conduit, a portion of the wall of said conduit adjacent said ?oat chamber being thickened, a main fuel nozzle pas sage extending from the lower part of said bowl through said thickened wall portion and opening into said mixture conduit, a fuel nozzle arranged in said nozzle passage and extending into said mixing conduit, an opening in an outerrwall of said ?oat chamber, a suction responsive dia phragm secured over said wall opening and formed with a central opening, a suction cham ber formed over the outer face of said diaphragm including a wall formed with an opening in align ment with the opening in said diaphragm, a tube secured at one end portion to the Wall de?ning ' the central opening in said diaphragm and mov able with said diaphragm, the outer end of said tube extending through and closely ?tting the wall de?ning the wall opening in said suction chamber, a passageway formed in said thickened wall and connecting said nozzle passage with said ?oat chamber, a metering ori?ce in said passage Way, a metering valve having one end portion extending into said tube and its other end por tion extending through said metering ori?ce, means for adjustably securing said metering valve in said tube, and means engaging said valve to maintain its axis in constant predetermined relationship with the axis of said metering ori?ce. ' ' ‘GEORGE M. BICKNELL.