US2740391A

US2740391A - Carbureting device

Info

Publication number: US2740391A
Application number: US429833A
Authority: US
Inventors: Frank R Busch
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-05-14
Filing date: 1954-05-14
Publication date: 1956-04-03
Anticipated expiration: 1973-04-03

Description

April 3, 1956 F R, BUSCH 2,740,391

CARBURETING DEVICE Filed May 14, 1954 2 Sheets-Sheet l April 3, 1956 F. R. BUSCH CARBURETING DEVICE 2 Sheets-Sheet 2 Filed May 14, 1954 mm #WH Ww m2 W., ,m Q W QN... QQ Nm a@ Q5 @w 1 I Y irwm w -w @N q J QQ Mw uw ,mv lfrlll: Q ,Q @Y www@ www United States Patent O CARBURETING DEVICE Frank R. Busch, Cicero, Iii. Application May 14, 1954, Serial No. 429,833

Claims. (Cl. 12S-119) The invention relates to carburetors and has reference more particularly to carburetors having a cone throttle so positioned in the air passage as to have its apex directed toward the incoming air, and wherein a metering effect affording optimum mixtures of fuel and air is achieved by a nozzle-controlled air orifice and by a needle-controlled fuel passage, both having communication with a stepped formation on the periphery of the cone throttle.

An object of the present invention is to provide a carburetor of simple design and construction, which will have a minimum number of working parts to conserve time, labor and essential materials in its manufacture, and which will incorporate an improved arrangement of fuel and air passages capable of correctly proportioning the fuel and air supplied to the engine for the entire range of speeds thereof, from an idling speed to a full open throttle speed.

Another object is to provide a carburetor having a cone throttle as described and which is mounted for movement in a tapered air passage for controlling the supply of the fuel-air mixture to the engine. p

Another object of the invention resides in the provision of a carburetor having a cone throttle and which is formed with stepped .surfaces at the fuel discharge openings therein whereby the desired rich mixture is produced at idling and low throttle speeds, and wherein the contour of the throttle forwardly of the stepped surfaces controls the transition of the combustible mixture from rich to lean as the throttle is moved from an idling position to a cruising position.

Another object of the invention yis to provide a carburetor of the cone throttle type VVwherein vthe throttle is 'movable and is operatively associated with a xednozzle 'to provide a nozzle-controlled oriiice for admitting Vpn'- mary 'air and is also operatively associated `with a `fixed needle to provide a needle-controlled passage for admitting fuel, the said structure insuring maximum atomization and evaporation of the fuel to produce the best and most economical mixture for varying `load conditions at various speeds. During operation of the present `carburetor the fuel and air admitted by the passage and orifice respectively, unite Within the throttle and the resulting mixture is injected into the secondary air stream from openings disposed around the periphery of the cone throttle and located at the stepped formation on the throttle.

Another object is to Vprovide a carburetor having a movable cone throttle so constructed and arranged that its `movement will vary the size of the nozzle-controlled oriiice `to meter the primary air admitted by the orifice 'andwhichwill also vary simultaneously the size of the needle-controlled passage .to meter the fuel admitted 4by the passage, the said fuel passage becoming progressively larger as the 'cone throttle is moved .from an idling position to a full open throttle position, and the air vorifice becoming progressively smaller on the throttle as the throttle is moved in the same direction.

2,740,391 aatented Apr. 3, 1956 ICC A more particular object of the invention is to provide cone throttle structure for a carburetor wherein the needle-controlled fuel passage and the .nozzle-controlled air orifice are disposed coaxially of the cone throttle, thereby simplifying manufacturing and achieving the maximum economy in construction since only one moving part is required. j

A still further object is to provide novel and improved carburetor structure which will accomplish the above lobjectives in an efficient manner, which may also have combined therewith an automatic system for kignition control, and wherein the carburetor will permit full retard of spark timing at idling speeds, or alternately complete control of spark timing under all operating conditions.

A further object is to provide a carburetor of the cone throttle type which will have a balance cylinder in operative association with the throttle to prevent the manifold suction from pulling the throttle open.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specication, ldrawings and claims appended hereto.

In the drawings which illustrate an embodiment of the invention, and wherein like reference characters are used to designate like parts- Figure l is a sectional view taken longitudinally through the center of the present carburetor and showing the cone throttle in idling position;

Figure 2 is a longitudinal sectional view similar to Figure l but showing the cone throttle in a cruising speed position;

Figure 3 is an elevational view, parts being shown in section, of the present cone throttle;

Figure 4 is an elevational view, parts being shown in section, of the fixed nozzle with which the cone throttle is operatively associated; and

Figure 5 is an elevational view of the needle which controls the size of the fuel passage as the throttle is moved.

Referring to the drawings, Figures 1 and 2, the carburetor selected for illustrating the present invention consists of a housing 20, including the body portion 21 at the air inlet end and the manifold portion 22 at the manifold end. The said parts of the housing are `suitably joined at 23 and during operation of the carburetor air is admitted at the end opening 24, which opening is provided with the 4strut 25. Said air passes into the carburetor where the same is mixed with the liquid fuel to 'form a combustible mixture and which is supplied in regulated amounts tol the engine through the manifold opening 26 according to load conditions.

The air inlet opening A24 leads to the venturi passage of the carburetor comprising the central portion 27 which is materially reduced in diameter with respect to the end opening 24 and with respect to the flaring opening 28 immediately beyond the central portion. The central portion 27, which is located between the diametrical strut 25 and the voutwardly flaring end 28, is provided With a sleeve 30 having bevelled edge 31. The sleeve is so positioned in the central portion 27 as to overlie the groove 33 extending circumferentially `on the inside wall of the body portion 21. This posi- 'tioning of the sleeve 30 is designed to leave a circumferential opening 34 through which air may flow during idling operation and which is thus injected into the secondary air stream flowing rthrough the passage of the carburetor. Air is admitted to groove 33 since the same has communicating relation with vthe air passage 35, extending through the wall of the body portion 21 and .terminating at the forward end of the strut V25. A

portion of the air entering the inlet opening 24 will be diverted into Vpassage 35. The connecting `opening 36'- between groove 33 and passage 35 is controlled by the needle valve V37 which may be adjusted to regulate the quantity of air permitted to flow from passage 35 into groove 33. .v

The liquid fuel to be mixed with the air to produce the combustible mixture supplied to the engine is admitted through strut 25, the same being cored centrally as at 40, into which cored opening there is fitted the tube 41. Said tube terminates short of the bottom end of the cored opening providing chamber 42. and at its upper end the tube has suitably threaded thereto the fuel supply pipe 43 which communicates with a conventional lioat bowl of the fuel system. From the chamber 42 the fuel is delivered to the fixed nozzle 44. VSaid nozzle, as shown in Figure 4, includes the threaded end 45, the intermediate abutment 46, and the nozzle proper 47, which is of tapering formation that increases in diameter in a direction outwardly from the abutment 46. Accordingly, the terminal end 48 of the nozzle has the greatest diameter and this end provides a passage 59 as a result of the inwardly directed lips 51. The nozzle 44 is fixed to the strut 2S by having its threaded end 45 threaded to the strut centrally thereof and which accordingly locates the nozzle at the center of the sleeve 30 and coaxially with respect to the movable throttle structure, which will now be described.

The cone throttle of the present carburetor is identified by numeral 52 and is shown in elevation and partially in section in Figure 3. The throttle is generally cone-shaped and is so positioned in the air passage of the carburetor as to have its apex directed toward the incoming air constituting the secondary air stream. The throttle is provided With a central opening 53 extending from end to end thereof and in accordance with the invention the nozzle 44 has location within said opening. The cone insert 54 is located in opening 53 at the apex end of said opening and as a result of the inwardly directed lip 55 the same provides an orifice with respect to the tapering exterior surface of the nozzle. The opposite end of opening 53 receives the shaft 56 which supports the cone throttle and mounts the same for movement. Said shaft is fixed to the cone throttle as at 57 and said shaft extends rearwardly, passing through bearing 58 in wall 59, and through bearing 60, provided by the rear wall 61 of the manifold portion 22. Said

end walls

59 and 60 in combination with the cylindrical wall 62 provides the piston chamber 63 within which is located piston 64. Said piston is fixed to shaft 56 as at 65 and accordingly said piston has movement within its chamber upon movement of the shaft to move the cone throttle to and from idling and cruising positions.

It was previously explained that the liquid fuel is admitted to the xed nozzle 44. InV accordance with the invention, the passage 50 forms a fuel passage and which is needle controlled since the tapering end 66 of needle 67 is positioned axially of the cored end of shaft 56 and accordingly extends through passage 50 into the nozzle 47. Needle 67 is tixedly secured at 68 to a backing member 70 having location within the cored rear end of shaft 56. The cored opening at this end of the shaft receives the coil spring 71 and which accordingly seats against the end of the cored opening to applypressure against backing member 7d in a rearward direction Whereby the needle 67 is properly positioned by the set screw 72. The set screw, as best shown in Figure l, has threaded relation within the threaded plug 73 and said screw is locked in adjusted position by nut 74. The tension of coil spring 71 is such as to Vmaintain the backing member 70 in contact with the set `screw 72 so that by adjustment of the set screw the relative position of needle 67 within the shaft 56 can be accurately adjusted.

It will be observed that the tapering end 66 of the needle is concentric with respect to 'passage' 50' of lthe 4 nozzle. It will also be observed that the nozzle 44 is concentric with respect-to cone insert 54. Said cone inl sert and the nozzle accordingly provide an orice which admits air to the interior of the cone throttle and since the orice varies in size as the cone throttle is moved, the orifice can accordingly be said to be nozzle controlled. In a similar manner passage 50 provides a passage through which fuel flows into the interior of the cone throttle and since the tapering end 66 of the needle is located in said passage the same can be said to be needle controlled. The passage 50 progressively increases in size as the throttle is moved from an idling position into an open throttle position, whereas the orifice progressively decreases in size as the throttle moves in the same direc tion.

In operation of the present carburetor the cone throttle 52 is moved to and from idling and open positions by movement of shaft 56, the accelerator of the engine connecting with the pin 75 by Ywhich movement may be imparted to the shaft. With the cone throttle in an idling position, such as shown in Figure 1, the fuel passage 50 is restricted by the needle end 66 almost to a maximum extent, although the size of the passage thus provided is such as to admit to chamber 76 the required amount for an idling speed. The primary air to be mixedwith said fuel is admitted by the orifice, which is relatively small in size at a closed throttle position, since the front face 55 of the cone insert is located closely adjacent 'the face of the nozzle. From chamber 76 the fuel in admixture with primary air is caused to ilow radially outward through the openings 77 formed in the cone throt tle. Said openings terminate at the stepped surface 78 formed in the periphery of the cone throttle and which may comprise a step that interrupts the cone taper of the throttle. I i The stepped cone configuration constitutes an important feature of the present invention. The structure assists in producing certain modes of operation whereby the present carburetor delivers a fuel and air mixture of proper proportion' for all speeds. At small throttle openings the stepped cone configuration reduces suction at the fuel passage because the cross-sectional area of the venturi passage in theplane of theljdischarge holes 77`is considerably larger` than that immediately rearward where the actual throttling control of the air-fuel supplyvto -the engine takes place. The increased area results in lower air velocity and consequently lower suction at the discharge hole 77 and thus a lower suction at the needle controlled fuel passage. Without the constructional feature of the stepped .surface on theV cone the suction at the fuel passage during small throttlev openings would be extremely high, necessitatingextremely accurate construction of all component parts and an impractically small area for fuel discharge. l f

Another feature of thestepped cone resides inthe fact that the structure constitutes an elfective means of governing idle mixtures and also makes possible the desired transition from an idling to a cruising mixture. Since the surface of the cone imediately in front of the discharge hole 77 will comeinto close relation with the walls of the venturi passage when the throttle isV substantially closed, there is formed a restriction in advance of the `holes 7,7. The result is to create an increased suction at the openings 77 which producesv an over-rich fuel mixture. This over-rich Vfuel mixture can then be ad'- justed so as to secure the properl fuelair ratio by ropening the idle mixture adjusting screw 37. By opening said screw the air supply to the groove33 is increased, which results in an increased air supply being delivered to the region of the discharge holes 77. Accordingly,'the suction at said holes can be reduced with a corresponding `reduction in the suction in the fuel passage and a decrease in the amount of fuel supplied to the engine. Also by controllingv the contour of the cone in advance of thevdischarge holes 77, it is possibleto control thearea of passage at the plane of the rearward end of the venturi sleeve for any given small throttle opening. It is therefore possible to vary the suction at the discharge openings 77.

Another reason why the stepped cone construction is important is due to the elect produced by the air ow past the step which becomes increasingly effective as the throttle is moved into full open position. With a variable venturi carburetor, the fuel vaporization is poorest at low speeds and at full open throttle positions. Since it is desirable to have the most thorough fuel vaporization under all conditions, the stepped construction on the cone serves this function, since it increases the suction at the discharge openings 77 for all open throttle positions.

The nozzle structure of the invention also aids in provivding a rich fuel mixture at idling speeds by reason of thenarrow peripheral channel which serves as an entrance to the air orice at said idling speeds. Said narrow peripheral channel is provided by the abutment 16 and by the approaching end of the cone insert 55, and said channel becomes progressively smaller as the cone throttle moves toward the abutment. Also the shape of the cone throttle from the stepped surface 78 to the apex is irnportant in the present carburetor since the shape thereof serves to control the transition of the mixture from rich to lean as the cone throttle is moved from idling into a cruising position. 'Ihe air admitted by the needle valve 37 will likewise have an effect on the richness of the mixture at idle speeds and above, and during test runs of the engine the needle can be adjusted to secure the optimum fuel-air ratio.

In place of openings 77` in the cone throttle the said throttle may be constructed of two parts having a spaced relation to form an annular fuel discharge opening. In all cases, whether the individual openings are employed, or whether a single annular opening is used, the same are relatively small in size to effect an intimate mixture or emulsion of the fuel and air and the lsaid fuelv discharge opening or openings also perform a directional eifect in properly injecting the mixture into the secondary air stream.

The piston 64 is located within piston chamber 63 of the balance cylinder and said piston is suitably xed to the shaft 56 so as to move with said shaft. The rear wall 61 of the balance cylinder is provided with anopening 80 leading to the atmosphere. The front wall '59 is provided with an opening 81 leading to the fuel mixture chamber of the carburetor. k".I'he structure consisting of piston 64 operating within the piston chamber 63 and being responsive to atmospheric air on one side and subatmospheric pressure on the opposite side such as prevails within the carburetor, is eifective to prevent the cone 0 throttle 52 from being drawn into an open position by the suction of the engine. The operation of the balance cylinder is such as to hold the cone throttle in any position between a fully open and a fully closed throttle location.

The carburetor of the present invention is adaptable for use in conjunction with an automatic system for ignition timing control. In the modification shown in Figure l the pipe 82 is operatively connected to a conventional system for ignition control wherein the spark timing is controlled solely by the degree of vacuum created in the carburetor. In other words, the higher the net vacuum, the more the spark is advanced. Said pipe has connection with two branch pipes, one identied by numeral 83 having connection with portion 21 of the carburetor at the bore 84, which terminates in opening A85 located in sleeve 30. The other branch pipe 86 has connection with the manifoldportion of the carburetor and 'communi- Cates with port 37, terminating in the cylindrical wall of the balance cylinder. It should be borne in mind that the automatic system for ignition timing is controlled entirely by a vacuum diaphragm Working against spring tension. Said diaphragm has connection with pipe 82 and therefore the higher the Vva'ctuiin in pipe 82, the `greater Cil the degree of spark advance. In Apractice the Vorifice will be somewhat larger in size than that at `87. Since the vacuum in pipe 82 will be the algebraic sum of the vacuum at 85 and 87, it follows that the spark advance will be a maximum under .conditions of high air flow through the venturi passage and relatively high manifold vacuum, since a high vacuum is produced at 85 and87. A retarded spark will result when the throttle is positioned for low engine speeds since air velocity through the venturi passagewill be low and manifoldv'acuum will be near zero. A fully retarded spark will also be produced during idling speeds since the port 37 will be closed by piston 64 and air velocity through the venturi passage will be low, to thus result in near zero vacuum 'atjs Any air bleeding past the piston tending to cause a 'vacuum at 87 will be counteracted by air owing from 8S to 8,7 and thus the creation of a vacuum in pipe 82 is eec'tively prevented.

The modification shown in Figure 2 contemplates a more conventional system for spark timing control. The distributor in the automatic system employed with this modification contains centrifugal weights which advance the spark as engine speed increases. Also a diaphragm control is provided which further advances the spark in response to manifold vacuum. The port 87 serves as 'the connection to the intake manifold but since it is desirable for the engine to idle with a fully lretarded spark, the port 87 is arranged so that the piston will cover it when the throttle approaches a fully closed position. Since ,leakage past the piston will eventually cause the vacuum at 87 to rise, the port 88 is provided, being connected by passages 9, and which port is open to the atmosphere when the throttle is in a substantially closed position. The port 38 thus prevents any vacuum build-up at 87. As 'soon as the throttle is moved from substantially closed positions into open positions, the -port 87 is placed in communication with the manifold and the port 88 i's closed by piston 648. The manifold vacuum will be instantly c'o'mmunicated through pipes 86 and 82 to the automatic s'y'stem for spark timing control.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings as various other forms of the device will of course be apparent to those skilled in the a'rt without departing from the spirit of the invention or the 'scope of the claims.

What is claimed is z l. In a carburetor, in combination, a casing providing an air passage having an air inlet end and a m'anifoldl'su'ctio'n end, an annular sleeve located between the 'air'nl'et end and the manifold suction end and constituting the central portion of .the air passage, a cone throttle di'sposed in the manifold end of the air passage and mounted for movement toward and from said sleeve, said cone throttle having a central recess therein and which has an orifice opening at the apex end and is closed at the opposite end, a needle extending into the central recess lfrom the closed end, a fuel discharge nozzle having its discharge end concentrically located within the central recess, the said needle projecting into the said discharge end of the nozzle to form a restricted passage forvmetering fuel delivered to the central recess, said orifice opening in combination with the nozzle providing a restricted ipa'ssage for metering air delivered to said central recess, and other openings in the cone throttle communicating with the recess and terminating at Athe periphery of the throttle..

2. ln a carburetor, in combination, a casing providing an air passage having an air inlet end and a manifold suction end, an annular sleeve locatedbetween the 'air inlet end andthe manifold suction end and constituting 'the central portion of the air passage, a 'cone throttle disposed in the manifold end of the air passage and having its apex end 'directed towardthe incoming air, means mounting the cone throttle for movement axially of the sleeve `in a 'direction Atoward and from the same, 'said conethrot-tle 7 having an axial recess therein and which yhas an orice opening at the apex end and is closed at the opposite end, a needle extending into the axial recess from the closed end, a fuel discharge nozzle having its discharge end directed toward the manifold suctionl end of the air passage and being concentrically located within the axial recess, the said needle projecting into the said discharge end of the nozzle to form a restricted passage for metering fuel delivered to the axial recess, said orifice opening incombination with the nozzle providing a restricted passage for metering air delivered to said mial recess, and other openings in the cone throttle communicating with the recess and terminating the periphery of the cone throttle. y 3. A carburetor as defined by claim 2, wherein the end of the needle extending into the axial recess is tapered from a maximum diameter at the closed end of the recess to a minimum at the end within the discharge nozzle, and wherein the outer surface of the nozzle also tapers in contour from a lminimum diameter at the fuel inlet end to a maximum diameter at the discharge end within the axial recess.

4. A carburetor as defined by claim 2, wherein the means mounting the cone throttle for movement includes a mounting shaft and a balancing cylinder located at the `manifold suction end of the air passage, said shaft extending through the end walls of the balancing cylinder whereby the shaft is supported in a manner permitting said movement of the shaft and throttle, the rear wall having an atmospheric opening therein, the opposite wall also having an opening therein and which leads to the manifoldv suction end of the air passage, and a piston within the balancing cylinder fixed to the shaft for movement therewith.

5. ln a carbureor, in combination, a casing providing an air passage and which extends from an inlet end to a manifold suction end, an annular sleeve positioned in the passage in contact with the walls of the casing and located centrally between the inlet end and the suction end, a fuel supply nozzle xedly supported from the casing and disposed axially of the sleeve with its discharge end directed toward the suction end of the air passage, a cone throttle in the manifold suction end of the air passage and mounted for movement with its apex end toward the sleeve, said cone throttle having a central recess therein providing an orifice opening at the apex Vend and which is closed at the opposite end, a needle extending axially of the central recess from the closed end thereof, said fuel supply nozzle also being normally located within the central recess concentrically of the same, said needle projecting into the discharge end ofthe nozzle to form a restricted lpassage for metering fuel delivered to the central recess, said orifice opening in combinaton with the nozzle providing a restricted passage for metering air delivered Vto said central recess, and other openings extending radially of the cone from the recess to the periphery thereof for conducting the fuel and air mixture from said recess and for discharging the same into the air passage.

6, A carburetor as defined by claim 5, wherein the end of the needle extending into the central recess is tapered from a maximum diameter at the closed end of the recess to a minimum at the end within the discharge nozzle, and wherein the outer surface ofthe nozzle also tapers in contour from a'minirnum diameter at the fuel inlet end to a maximum diameter at the discharge end within the central recess,

7. In a carburetor, in combination, a casing providing an air passage, a fuel supply nozzle disposed axially Within the air passage, said nozzle extending in the direction of air flow and having an exterior taper providing a discharge end of maximum diameter, a throttle of generally cone shape located in the air passage in axial relation with the nozzle, the apex end of said ythrottle being directed against said air flow, said throttle having a central recess therein forming an orifice opening at the apex end and which is closed at its opposite end, the said nozzle extending into the central recess whereby the orifice opening forms with said nozzle a restrictedpassage for metering air admitted to the recess, a needle'projecting from the closed end into the recess y and extending into the dis"- charge end of the nozzle, said needle forming a restricted passage at the discharge end of the nozzle for metering the fuel discharged linto the central recess, said throttle having openings therein and which extend radially from the recess to the periphery of the throttle, and means mounting the throttle and needle as a unit for axial movement with respect to the nozzle.

8. A carburetor as defined by claim 7, wherein the needle also tapers from a maximum `diameter adjacent the closed end of the recess to a minimum at the end within the nozzle, and whereby movement of the throttle from an idling position to cruising positions will progressively decrease the size of the passage for metering air and will progressively increase the size of the passage for metering fuel.

9. In a carburetor, in combination, a casing providing an air passage, a fuel supply nozzle disposed axially within the air passage and lixedly supported from the casing, said nozzle extending in the direction of air iiow and having an exterior taper providing a discharge end of maximum diameter, a cone throttle located in the air passage in axial relation with the nozzle, the apex end of the throttle being directed against said air ilow, said throttle having a central bore, a mounting shaft fixed to the throttle by fitting in said bore from the rear of the throttle, said shaft terminating short of the length of the bore to form a chamber having an orifice opening at the apex end of the throttle, said nozzle extending into the chamber whereby the orifice opening forms with said nozzle a restn'cted passage for metering air admitted to the chamber, a tapering needle projecting from the mounting shaft into the chamber and extending into the discharge end of the nozzle, said needle forming a restircted passage at the discharge end of the nozzle for metering the fuel discharged into the chamber, said throttle having at least one opening extending radially from the chamber to the periphery of the throttle for discharge of the fuel and air mixture from the chamber, and means supporting said mounting shaft for movement to move the throttle axially of the air passage. l

l0. ln a carburetor, in combination, a casing providing an air passage having a central portion of reduced cross-sectional area, a sleeve in the air passage defining the central portion, a fuel supply nozzle disposed axially within the sleeve and being iixedly supported from the casing, said nozzle extending in the direction of air flow and having an exterior taper providing a discharge end of maximum diameter, acone throttle located in the air passage beyond the sleeve and having its apex end directed against said air flow, a tubular mounting shaft for the cone throttle, said cone throttle having a central bore for receiving the mounting shaft whereby the throttle is fixed thereto, said shaft extending into the bore from kthe rear and terminating short of the length of the bore to form a chamber having an oriiice'opening at the apex end 'of thethrottle, said nozzle extending into the chamber whereby the orifice opening forms with said nozzle a restricted passage for metering air admitted to the chamber, a needle disposed in the tubular mounting shaft and having a tapering end projecting into the chamber, said tapering needle end extending into the discharge end of the nozzle and forming a restricted passage at the discharge end for metering the fuel admitted to the chamber, said throttle having at least one opening extending radially from the chamber to the periphery of the throttle for discharge of the fuel and air mixture from the chamber, and means supporting said tubular mounting shaft for movement to move the throttle axially of the air passage.

1l, A carburetor as deiinedby claim l0, wherein the casing has a circumferential groove in the central portion so located with respect to the downstream edge of the sleeve as to form an exit opening into the air passage, a bore in the wall of the casing leading from the inlet end of the air passage to said groove, and a needle valve in the bore for controlling the air admitted to the groove.

12. A carburetor as defined by claim 10, additionally including a balance cylinder, said mounting shaft extending through the balance cylinder, a piston fixed to the mounting shaft and located within the cylinder, an atmospheric opening in one end wall of the cylinder, and a suction opening in the other end wall leading to the air passage at a point beyond the cone throttle.

13. In a carburetor, in combination, a casing providing an air passage having an air inlet end and a manifold suction end, an annular sleeve located between the air inlet end and the manifold suction end and constituting the central portion of the air passage, a cone throttle disposed in the manifold end of the air passage and mounted for movement toward and from said sleeve, said cone throttle having a central recess therein and which has an orifice opening at the apex end and is closed at the opposite end, a needle extending into the central recess from the closed end, a fuel discharge nozzle having its discharge end concentrically located within the central recess, the said needle projecting into the said discharge end of the nozzle to fonn a restricted passage for metering fuel delivered to the central recess, said orifice opening in combination with the nozzle providing a restricted passage for metering air delivered to said central recess, other openings in the cone throttle cornmunicating with the recess and terminating at the periphery of the throttle, and said throttle having a stepped formation in the cone surface thereof and which aligns with the said other openings.

14. In a carburetor, in combination, a casing providing an air passage, a fuel supply nozzle disposed axially within the air passage and xedly supported from the casing, said nozzle extending in the direction of air ow and having an exterior taper providing a discharge end of maximum diameter, a cone throttle located in the air passage in axial relation with the nozzle, the apex end of the throttle being directed against said air ow, said throttle having a central bore, a mounting shaft fixed to the throttle by fitting in said bore from the rear of the throttle, said shaft terminating short of the length of the bore and forming a chamber having an orifice opening at the apex end of the throttle, said nozzle extending into the chamber whereby the orifice opening forms with said nozzle a restricted passage for metering air admitted to the chamber, a tapering needle projecting from the mounting shaft into the chamber and extending into the discharge end of the nozzle, said needle forming a restricted passage at the discharge end of the nozzle for metering the fuel discharged into the chamber, said throttle having at least one discharge opening extending radially from the chamber to the periphery of the throttle for discharge of the fuel and air mixture fram the chamber, and said cone throttle having a stepped formation on the periphery thereof and which aligns With the said discharge opening.

15. In a carburetor, in combination, a casing providing an air passage, a venturi sleeve located in the air passage substantially centrally of the same, a fuel Supply nozzle disposed axially within the sleeves and being fixedly supported from the casing, said nozzle extending in the direction of air flow, a cone throttle having it apex directed toward the incoming air and being operatively associated with the fuel supply nozzle, means mounting said throttle for movement with respect t0 the fixed nozzle including a mounting shaft, a balance cylinder, said mounting shaft extending through the balance cylinder, a piston fixed to the mounting shaft and located Within the cylinder, one end wall of the balance cylinder having an atmospheric opening and the other wall having an opening leading to the air passage at a point beyond the cone throttle, and a spark timing control system in associated relation with the casing, said system including a tube having connection with the balance cylinder adjacent that end thereof having the opening leading to the air passage.

References Cited inthe tile of this patent UNITED STATES PATENTS 1,818,928 Kreher Aug. 11, 1931 1,983,255 Wahlmark Dec. 4, 1934 2,332,586 Mallory Oct. 26, 1943 2,471,111 Mallory May 24, 1949