US1973362A

US1973362A - Carburetor

Info

Publication number: US1973362A
Application number: US669432A
Authority: US
Inventors: Weiertz Axel Hugo; Weiertz Per Axel Reinar
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-05-13
Filing date: 1933-05-04
Publication date: 1934-09-11
Anticipated expiration: 1951-09-11

Description

3 Sheets-Sheet l Sept. 11,- 1934. A. H. wEn-:RTz Er AL CARBURETOR Filed May 4, 1933 Sept. 11, 1934. A. H.'wElERTz ET AL CARBURETOR Filed May 4, 1935 3 Sheets-Sheet 2 MY MX.

Sept 11, 1934- A. H. wElERTz Er Al.v 1,973,362

CARBURETOR Filed May 4, 1955 3 Sheets-Sheet 3 Patented Sept; 11, 1934 PATENT OFFICE clinBUaE'roR Axel Hugo Weiertz and Per Axel Beinar Weiert Svedala, Sweden Application May 4, 1933, ySerial No. 669,432

. In Sweden May 13, 1932 21l claims.

This invention relates to carburetors for internal combustion engines, of the type in which the fuel is delivered to the air through a fuel sprayer provided with a circumferentially extending nozzle slot or with a plurality of circumferentially distributed nozzle orifices, opening into an air passage of annular cross section formed `between the fuel sprayer and the carburetor casing.

The invention in its broadest aspect is chara'cterized substantially in that both the carburetor casing and the axially disposed fuel sprayer ltherein taper in the direction of flow of the air through the said passage, and in that lo the tapering fuel sprayer is provided with the circumferentially extending nozzle slot or with the circumferentlally distributed nozzle orifices near its widest end and at-this end has a diameter which is substantially greater than, foris adjustable by means of an axially movable air control valve which may consist of the tapering or conical fuel sprayer itself or of a sleeve mounted in the carburetor casing, and preferably this valve constitutes the sole manually operated means of the carburetor for controlling the feeding of the engine for varying the power thereof. J

Because of the relatively great diameter of the tapering'fuel sprayer at the circumferentially extending. nozzle slot the air flowing through the air passage surrounding the fuel sprayer is caused to pass the said nozzle slot in a relatively thin layer, so that the whole of the air is efficiently utilized for drawing the fuel into .the air stream and so that the fuel is very intimately and uniformly admixed with parts of the air stream without necessitating ny substantial throttling of the air stream at any point of the air passage when the engine is running at ordinary or full load. For instance, when the said air control valve is opened for allowing the engine to run at full load, the free section of the air passage adjacent the circumferentially extending nozzle slot may be about as great as, or even. greater than, the free section of the intake manifold or suction conduit of the engine, to which the carburetor is to be connected. For this reason the resistance to suction offered by the carburetor will kbe relatively small and, con- The free section of the 95' air passage surrounding the tapering fuel sprayer sequently, the cylinders of the engine will be better filled with explosive mixture, so that the1 power and emciency of the engine will be increased, whereby a reduction in fuel consumption is obtained. The more intimate and uni- 60 form admixture of the fuel with the air which. is obtained, also contributes to the saving of fuel, and due to this more intimate and uniform l ladmixture of the fuel with the air and when preheating the fuel in the carburetor in a manner 66 hereinafter to be described it is possible to use the carburetor also with heavy fuel oils for instance in ordinary automobile engines and obtain complete and smokeless combustion.

Preferably the carburetor is constructed as a 'I0 down draft carburetor, and preferably the usual float control means for controlling the fuel supply to the carburetor is. mounted within the hollow fuel sprayer, whereby a concentrically built 'y carburetor of a very compact and practical construction is obtained which is easy to manufacture and assemble.

Further objects and novel features of the invention will be apparent from the following detailed description of several embodiments thereof, reference being had to the accompanying drawings in which each ofthe Figures l, 2,

3 and 4 is an axial section of one of said ernbodiments of the carburetor and in which like characters refer to Alike or analogous parts throughout the several figures.

In the embodiment shovwn in Fig. 1, there is provided within a conical casing 1 a conical, hollow fuel sprayer' comprising an upper part 2 and-a lower, tapering part 3. The upper part 2 90 of the sprayer is screwed into the casing-1 by the screw threads 6l, so that the said sprayer itself also serves as an air control valve for adjusting the free section of an air passage 4 of lannular cross section'formed between the conical 95 casing 1 and the conical fuel sprayer which is Aprovided with a circumferentially extending noz- ,zle slot 5 formed between the parts 2 and 3 of conduit.

within the hollow sprayer and screwed to the upper part 2 thereof, which part forms a cover for the said float chamber. The fioat 7 in the float chamber 6 controls the fuel supply to the float chamber through a Valve 8, and the fuel supply conduit 9 connected to the valve 8 consists of a hose of flexible piping which does not prevent the movement of the fuel sprayer 2, 3 when it is adjusted for controlling the air suplply'to the engine. Through a central opening,

controlled by a needle valve 10, in the bottom of the float chamber 6 and a passage l1 formed between the lower part 3 of the sprayer and the float chamber 6, the fuel passes to a preliminary mixing chamber 12 which merges in to the nozzle slot 5 and similar to this is formed between the parts 2 and 3 and extends all around the float chamber 6. The lower part 3 of the sprayer is screwed on a hollow stud 13 depending from the oat chamber 6. Above the opening of the passage 11 into the preliminary mixing chamber 12 air inlet openings 14 to this chamber are provided in the part 2. At the upper end of the casing 1 there is provided all around the sprayer an air inlet to the passage 4, and over this air inlet there is provided a cover plate or hood l5 Within which air purifying means of any suitable kind may be arranged.

The needle valve l0 is biased upwards against its seat by meansI of a spring 16, and an axially movable, centrally disposed spindle 17, guided in the cover for the floating chamber and coacting with the upper end of the needle valve 10, has its upper end in contact withan adjusting screw lcaried by a part 19 that is secured to the casing 1. On the spindle 17 which is biased upwards against the adjusting screw 18 by a spring 20, there'is provided under the float 7 a plunger like disk 21 provided with openings 22 controlled by a valve disk 23 which is axially movable on the spindle 17 under the disk 21.

'Ihe movable fuel sprayer is provided with an arm 24 which, when the carburetor is used in connection with the engine of a conventional automobile for instance, is to be coupled to the usual throttle pedal, so that the fuel sprayer can be screwed up and down in the casing 1 by the driver operating this pedal vin the usual manner. For limiting the shutting olf movement of the sprayer an adjustable abutment in the formof an adjusting screw 25 or the-like may be provided, through which lthe carburetor can be adjusted for obtaining any desired light running speed of the engine.

The operation of the carburetor as now described is as follows. As will be seen from the drawings, the air which is drawn in by the engine through the carburetor, is caused, on account of the great diameter of the fuel sprayer at the circumferential nozzle slot 5, to pass'this nozzle slot in a relatively thin layer, so that all parts of the air stream are efficiently utilized for drawing the fuel into the passing air and so that the fuel-is admixed in a more intimate and uniform manner with all parts of the air stream without any high throttling or any abrupt change of the direction of now of the air, or of the explosive mixture formed, at any point of the passage 4. For instance, the free cross sectional area of the said passage 4 at the nozzle slot 5, when the air control valve formed by the fuel sprayer is fully opened, or nearly so, can be about as great as, or even substantially greater than, the free sectional area of the casing 1 at A float chamber 6 is concentrically mounted' the lower end thereof connected to the intake manifold or suction conduit of the engine. On account hereof and due to the fact that the conventional gas throttling valve controlling the discharge outlet of the carburetor is dispensed with, the resistance to suction offered by this carburetor when the motor is running at ordinary or full load, is much reduced in comparison with ordinary carburetors having the said conventional gas throttling valve; and since the passage for the explosive mixture through the carburetor to the suction conduit of the engine is relatively free and unobstructed, the liability of the fine particles of the atomized fuel to condense on and adhere to the walls of the passage, or to recombine into larger drops is highly reduced. Through the openings 14 a small portion of the air enters into the preliminary mixing chamber-12 and is mixed therein with the fuel entering through the nozzle slot 5 into the main air stream the passage 4. This preliminary mixing of the fuel with a small portion of the air in the chamber 12 results in a better atomization and distribution of the fuel in the main air stream. When the fuel sprayer is screwed upwards for increasing the free section of the passage 4, the needle valve 10 is automatically opened more, and the plunger disk 21 is automatically moved downwards relatively to the oat chamber 6, whereby a pressure is exerted on the fuel in the float chamber, resulting in a forced fuel flow from the said chamber to the fuel nozzle 5. At this downward motion of the plunger disk 21.relatively to the float chamber 6 the openings 22 in said disk 21 are automatically closed by the axially movable valve disk 23. When the fuel sprayer is screwed downwards for decreasing the free section of the air passage 4, the needle valve 10 is moved towards its seat again, and the plunger disk 21 is moved upwards relatively to the float chamber 6, thereby retarding the fuel flow from the said vchamber 6 to the fuel nozzle 5. In this manner, if the needle valve is given the proper size and form, there is automaticallyl obtained at all times a proper accommodation of the fuel supply relatively to the air supply to the engine and also a highly desirable acceleration and retardation of .the fuel flow to the fuel nozzle when adjustingthe free section of the air passage 4 for increasing and retarding, respectively, the air supply to the engine.

In the embodiment shown in Fig. 2 the conical fuel sprayer 2, 3 is immovably mounted in the conical carburetor casing 1, an axially movable, conical valve sleeve 26 being provided for controlling the free section of the air passage 4. Preferably this sleeve l'26 is screwed by the screw threads 61 into the casing 1, so that the sleeve is adjusted by rotating the same and for this purpose is provided with the arm 24 which is to be coupled to the conventional throttle pedal, for instance, and coacts with the adjustable stop screw 25. 'Ihe needle valve 10 is connected to a piston or diaphragm 27 by means of which a chamber, provided in the lower part 3 of the fuel sprayer under the passage 11 and communicating therewith, is closed at its lower end.` This piston' or diaphragm is actuated by the vacuum created in the suction conduit of the engine when the engine is running. The needle valve 10 is biased against its seat by means ofv a spring 28 which is adjustable by means of a screw cap 29 screwed into a nut sleeve 30 which is screwed on a sleeve 31. This 4in are fastened to the upper part 2 of thefuel sprayer by means of a nut 33. The tubular stem 32 forms a guide for the spindle of the needle valve 10. A compensatory spring 35 is inserted between a collar 34 on the upper end of the spindle of the valve 10 and the nut sleeve 30.

In the operation of the carburetor according to Fig. 2 the needle valve 10 is automatically adjusted by means of the piston or diaphragm 27 accordingl to the vacuum created in the suction `conduit of the engine, so that the needle valve 10 is opened the more the lower the said vacuum is. Further the piston or diaphragm 27 through itsmovement, dependent on the said vacuum,- effects an acceleration and retardation of the fuel flow to the nozzle 5 when the said vacuumls increasing and decreasing respectively, the piston or diaphragm 27 actirg as a plunger on the fuel. In this manner there is automatically obtained a rapid 'and proper accommodation ofthe fuel supply in relation to the air supply to the engine according to the varying power consumption and to the desired speed of the en# gine, which is controlled solely by operating the air control valve sleeve 26. 'l

In the embodiment of the carburetor shown in Fig. 3 the air control valve sleeve 26 is fitted in an annular groove formed in the casing l Alnside a collar 36 provided on the said casing. Preferably the sleeve 26 is screwed into the collar 36 by the screw thread 6l andis of a diametercorresponding substantially to the diameter of the circumferential nozzle slot 5 of the fuel sprayer. By screwing the sleeve 26 up and down `the free section of the air passage 4 is varied for varying the air supply to the engine. The upper part 2 of the conical fuel sprayer is screwed on the float chamber 6 which is supported by the collar 36 and is secured thereto by means of screws 37. These screws 37 at the same time serve to retain the cover 33 on the float chamber. `The lower part 3 of the fuel sprayer is attached to the float chamber 6 by means of a centrally disposed screw nipple 39 forming the seat for the needle valve 10, the spindle of which is guided in a bore in the cover 38. The biasing spring 28 is disposed in the said bore in the cover 38, and a compensatoryl spring 46 is disposed under the diaphragm 27.

The fuel supply valve 8 is controlled by the float 7 through a lever `41 and consists of a ball which is pressed down on its seat by the lever 41 and is raised by the pressure of the fuel oil in the supply conduit 9 when the level of the fuel in the float chamber 6 sinks and the oat 7 descends. The float 7, however, is positively governed by the axial adjustment of the` air control valve sleeve 26 through a link and lever system and an axially movable pin 42, so that the float 7 is forced downwards in the float chamber 6 when thelsaid sleeve 26 is screwed downwards, that is, in the direction of opening the aii valve. Further a spring 43 is so connected in the said link and lever system that when screwing the valve sleeve 26 upwards, that is, in the direction of closing the air valve, this spring is tensioned and exerts an increasing lifting power on the iioat 7, whereby the float is4v ly adjustable sleeve 26. The lever 45 is pivoted on a trunnion 46 excentrically disposed on a shaft 47 journaled in the cover 38 for the float chamber. The shaft 47 is provided with an arm 48' and can be rotated by means of a Bowden cable 49 or the like connected to the said arm 48. Further the lever 45 is engaged, with a certain play, in a slot 50 or the like in the stem or spindle of the needle valve 10.

In the operation of the carburetor according to the embodiment described with reference to Fig. 3, the needle v'alve l0 is automatically controlled by the diaphragm 27 according to the vacuumcreated in the suction conduit of the engine, principally in the same manner as herein before described with reference to Fig. 2. This automatic control of the needle valve 10,

however, is limited by a certain positive actua- .ly in the direction of opening-the valve 10 at a suicient displacement of the .air valve sleeve 26 in the direction of opening the said air valve, and also positively moving the needle valve 10 in the direction of closing said needle valve at a suflicient displacement of the air control valve sleeve 26 in the direction of closing said air valve. ln other words, the play between the lever 45 a d the spindle of the needle valve 16 provides a limited range within which the lpiston or diaphragm 27 acting automatically under the influence of the vacuum created in the suction conduit of the engine, is free to adjust the position of the needle valve 10. This range is axially displaced through the displacement of the air control valve sleeve 26 and may Ialso beadiusted in relation to the ,position of the said sleeve 26 through displacement of the pivot 46 for the lever 45 by rotation of the shaft 47. The rotation of the shaft 47 for this purpose by means of the arm 48 and the Bowden cable 49 or the like may be performed manually or automatically for instance by means of a. thermostat exposed to the temperature of the air or of the vcooling water of the engine. Besides the link and lever system between the air valve sleeve 26 and the float 7 performs the following functions.

When the sleeve 26 is screwed downwards for starting the engine or for increasing the power thereof the float 7 is positively moved downwards in the oat chamber 6, so that the float by displacing the fuel in the float chamber causes the fuel therein to rise from a lower level, for instance the level 5l to a higher level, for instance the level 52', which may come up substantially to or evenbeyond the level at which the passage 11 opens into the preliminary mixing chamber l2. Through this occasional or temporary rising of the fuel level in the floatv chamber at the movement of openingthe air control valve there is obtained a desirable accel-v eration of the fuel fiow to the nozzle 5 -when the engine is to be started' or the power or speed thereof is to be increased. 'I'he downward movement of the float contributes to this effect also due to the float acting as a plunger forcing fuel from the ficat chamber to the nozzle 5. When the air valve sleeve 26 is screwed upwards for slowing down or stopping the engine the float 7 is raised, whereby the fuellevel in the float chamber is caused to sink vand the fuel flow tothe nozzle 5 is retarded. At the same time the spring 43 is tensioned isc more and lightens the float more, so that the float 7 will tend to keep the fuel at a lower level in the float chamber. In other words, for each different .position of the air control `valve 26 there exists a correspondingly different level at which the float 7 normally will keep the fuel in the float chamber by the control of the fuel supply valve 8; but when screwing the air valve 26 downwards or upwards to any desired position the fuel in the float chamber always is occasionally or temporarily raised or lowered, respectively, beyond the level corresponding to such position. In normally closed or idle position of the air valve 26 the corresponding fuel level lin the float chamber is, for instance, at 51', which is substantially below the level at which the passage l1 opens into the preliminary mixing chamber v12, so that it is not to be feared that the fuel shall run over inadvertently through the vnozzle slot 5 when the engine is at rest, even if the axis of the carburetor is materially out of the perpendicular. Even a substantial inclination of the carburetor when the engine is running has practically no inuence on the operation of the carburetor.

In the embodiment shown in Fig. 3 the preliminary mixture of fuel and air, which is formed in the chamber 12, may be preheated on its way to the nozzle slot 5 by means of a preheating device arranged within the preliminary mixing chamber 12 and consisting, for example, of rings 52 of corrugated metal plate fixed on insulating rings 51, so that the said metal rings 52form walls in the chamber 12 and are swept by the preliminary mixture passing to the nozzle slot 5. The said metal rings 52 serve as electrical heating elements which are heated by passing an electric current through the rings, electrical feeding conduits 53 being connected to the said rings 52 for this purpose. This preheating device is employed especially when using heavy fuel oils and in order to make it possible to start the engine directly on the heavy fuel. Due to the large heating surfaces offered by this preheating device which extends all around the fuel sprayer inside the nozzle slot 5, the preliminary mixture of 'fuel and air will be subjected to an efficient heating action immediately before the mixture is delivered through the nozzle 5 into the main air stream through the passage 4. On account of this preheating of the preliminary mixture the fuel contained therein enters into the relatively cold main air stream in wholly or partly vaporised condition, so that the fuel will be very intimately and uniformly mixed with the main air stream and simultaneously cooled thereby so that the vaporised fuel is again condensed, wholly or in part, in very fine particles which remain evenly distributed in the air. The hood 15 is provided with an inner wall 54 having a free lower edge projecting into an annular settling chamber 55 of U-shaped section. The air entering into the carburetor passes around the lower edge of the wall 54, whereby impurities in the air separate therefrom 'and settle in the settling chamber 55.

The embodiment shown in Fig. 4 is identical with the embodiment shown in Fig. 3 in all principal respects and differs therefrom substantially only in that the needle valve 10 is moved downwardly for, opening it, the diaphragm 27 in Fig. 3 being substituted by a piston 56 fitted in a bore in the cover 38, and the space above the said piston in the said bore being connected by means of a pipe 57 with the passage 4 in the casing 1, so that the vacuum therein is transmitted to the space above the piston 56. In accession hereto also the link and lever connection between the air valve 26 and the float 7 is constructed somewhat differently, as will be seen and understood without further explanation from the drawings. Further the preheating device in the embodiment according to Fig. 4 consists of a pipe 58 extending all around in the preliminary mixing chamber 12. This pipe 58 is swept by the preliminary mixture passing .to the nozzle 5 and is heated by passing a suitable heating medium, such as the exhaust gases from the engine or the cooling liquid for the engine, through said pipe. 'Ihe annular pipe 58 at d iametrically opposed points is provided with depending, tubular stems 59 and 6D through which the heating medium is passed to and from the pipe 58 and by which at the same time the fuel sprayer 2, 3 and the float chamber 6 secured thereto are fastened to the casing 1.

Although several preferred embodiments of the invention have been illustrated and described herein the invention is not limited to these embodiments which have been illustrated and described in detail for the sole purpose of ascertaining the nature of the invention and not in a limiting sense. The construction of the carburetor can be varied in different respects without departing from the scope of the appendant claims and, for instance, in all the em-l bodiments' shown the continuous nozzle slot of the fuel sprayer may be substituted by a number of separate nozzle orifices distributed all around the circumference of the conical or tapering fuel sprayer at or near the widest portion thereof,

where it has a diameter substantially greater than the internal diameter of the conical carburetor casing at the end thereof `to be connected to the intake manifold or suction conduit of the engine. construction of the carburetor thisl is built as a down draft carburetor it is not absolutely necessary to build the carburetor according to the down draft principle since the invention can also be applied to carburetors through which the air and explosive mixture formed are flowingl What we claim and desire to secure by Letters Patent is:

1. In a carburetor for internal combustion engines the combination of a conical casing, a conical, hollow fuel sprayer movably mounted in said casing coaxially therewith and tapering in the same direction a's the said casing and leaving between itself and the said casing a passage of annular cross section, said passage having an annular air inlet at the widest end and a discharge outlet at the other end of thesaid casing, the said conical fuel sprayer being provided adjacent its Widest portion with a circumferentially distributed nozzle opening into the said passage, the diameter of the said-.conical sprayer at the said Widest portion thereof being materially greater than the inner diameter of the casing at the discharge end thereof, means for supplying fuel to the said Vnozzle and manually operated means for axially adjusting the position of the said conical fuel sprayer relatively to the said casing for carying the free section of the passage between the fuel sprayer and the casing.

2. In a carburetor for internal combustion engines, the combination of a tubular casing Although in the preferred having its axis vertical and tapering towards its lower end, a substantially conical, hollow fuel sprayer coaxally disposed in said casing and leaving between itself and the inner Wall of said casing a passage having a ciroumferentially distributed air inlet at the upper end and a discharge outlet at the lower end of the said casing, the conical, hollow fuel sprayer being provided near its Widest portion with a circumferentially distributed nozzle opening into the said passage extending substantially all around the fuel sprayer, and the diameter of the conical fuel sprayer at the said nozzle being materially greater than the inner diameter of the tapering, ltubular casing at Vthe discharge end thereof, a yfloat`chamber disposed within the hollow fuel sprayer and communicating with the said nozzle, a float in the said oat chamber, a fuel supply valve controlled by said float, and means for controlling the said air passage by varying the free section thereof adjacent the said nozzle.

3. In a carburetor for internal combustion "engines, the combination of a casing substantially in the form of a frustum of an inverted cone, a hollow fuel sprayer substantially in the form of ari inverted cone disposed within the said casing coaxially therewith and provided near its widest portion with a circumferentially distributed nozzle opening in a passage formed between the said sprayer and the said casing and having an air inlet at the upper end and a discharge outlet at the lower end of the said casing, the diameterof, the conical fuel sprayer at the circumferentially disposed nozzle thereof being materiaily greater than the inner diameter of the. conical casing at the discharge end thereof, a float chamber disposed within. the hollow fuel sprayer coaxially therewith and provided in its bottom with a centrally disposed opening to a. fuel passage formed between the said oat chamberV and the bottom of the said hollow fuel sprayer and leading to the circumferentially disi posed nozzle of the fuel sprayer, means for con- IBO trolling the said central opening in the bottom of the noat chamber, a float inthe oat chamber, a. fuel supply conduit leading to the said float chamber, a fuel supply valve actuated` by the said float for controlling the fluid supply to the oat chamber, and means for controlling the said air passage between` the fuel sprayer and the surrounding casing by varying thefree section of the said passage adjacent the` said nozzle.

"4. In a carburetor as claimed in claim 3 the additional feature that the hollow fuel sprayer comprises an upper part and a lower part leaving between themselves at the circumference of the sprayer a continuous slot constituting the nozzle and inside the said nozzle an annular preliminary mixing chamber into which the fuel passage formed betweenfthe oat chamber andv amount of the air passing through the carburetor prises a valve sleeve mounted inthe casingco-` axially therewith and adjustable in axial direc-b the conical fuel sprayer at the circumferential.

nozzle thereof. p

6. In a carburetor as claimed in claim 3 wherein the means for controlling the central opening in the bottom of the float chamber comprises a needle valve the further feature that means are provided for automatically adjusting ,the position of the needle valve, in accordance with the vacuum in the discharge outlet of the casing..

7. In a carburetor for internal combustion engines, the combination of a casing having its axis vertical and tapering towards its lower end., a substantially conical, hollow fuel sprayer coaxially disposed in said casing and having a screw threaded connection therewith, whereby the said conical fuel sprayer may be screwed up and down in the said casing for controlling the freesection of an air'and mixing passage of uted nozzle opening in the said air and mixingr passage, and the diameter of the said fuel sprayer at the said nozzle being materially greater than the inner diameter of the tapering casing at the outlet end thereof, a float chamber mounted within the axially movable fuelsprayer Iso as to partake in the movement thereof and communicating with the said nozzle, a float in said oat chamber, a fuel supply valve controlled iby the said float, means adapted to control the communication between the oat chamber and the nozzle automatically in accordance with the axial adjustment of the fuel sprayer relatively to the casing, and means within the float cham.- ber for automatically effecting forced acceleration and retardation, respectively, of the fuel ow from the float chamber to the nozzle, when the fuel sprayer is screwed up and down, respectively, for increasing and decreasing, respec= tively, the free section of the said air and mixing passage.

8. In a carburetor as claimed in claim 7 wherem in the means adapted to control the communication'between the lloat chamber and the nozzle comprises a needle valve the further features that y float chamber, means being provided for controlling openings provided in the said plunger like disk. i

9. In a carburetor for .internal combustion engines, the combination of asubstantiallyconical, hollow fuel sprayer, an inclosing, corneal casing coaxial therewith and tapering in the same direction as the said fuel sprayer and forining together with the said fuel sprayer a main air and mixing passage of annular cross section, having an air inlet at the widest end and a discharge outlet at the other end of the said casing, thev said conical fuel sprayer being provided near its widest portion with a circumferentially distributed nozzle opening into the said/ passage near the air'inle't end thereof/:and the diameter of the said conical fuel sprayer at the circumferentially distributed nozzle being materially greater than the inner diameter of the conical casing at the discharge end thereof, heating means located in an annular preliminary mixing chamber formed in the hollow fuel sprayer adjacent the circumferential nozzle and communicating therewith and provided with air inlet openings, means for supplying fuel to the said preliminarylmixing chamberjand means for l controlling the said main air and mixing passage by varying the free section thereof adjacent the said circumferentally distributed nozzle of the fuel sprayer.

10. In a carburetor for internal combustion engines as claimed in claim 9, the further feature that the said heating means comprises electrical heating elements in the form of metal rings mounted in the annular preliminary mixing chamber and having surfaces swept by the preliminary mixture of air and fuel immediately before the delivery of said mixture through the nozzle into the main air and mixing passage.

11. In a carburetor for internal combustion engines as claimed in claim 9, the further feature that the heating means consists of an annular pipe mounted in the annular preliminary mixing chamber so as to be swept by the preliminary mixture before the delivery thereof through the circumferentially extending nozzle into the main air and mixing passage, means for passing a heating medium through the said pipe for heating it. v 12.*In a carburetor for internal combustion engines, the combination of a casing substantially in the form of a frustum of an inverted cone, a hollow fuel sprayer substantially in the form of an inverted cone, mounted in said casing coaxially therewith and comprising an upper part and a lower part leaving between themselves near the widest portion of the conical fuel sprayer at the circumference thereof a continuous nozzle slot and inside the said nozzle slot and mergingv therein an annular preliminary mixing chamber having air inlet openings pro` vided in the said upper part of the fuel sprayer, means for supplying fuel to the said preliminary mixing chamber, saidmeans including a float chamber within the said hollow fuel sprayer, a float in said float chamber and a fuel supply valve controlled by the said float, heating means located in the said annular preliminary mixing chamber and having heating surfaces adapted to be swept by the preliminary mixture of airand fuel for preheating said preliminary mixture immediately before delivery thereof through the said nozzle into a main air and mixing passage which is formed between the fuel sprayer and the surrounding casing and has an air inlet at thel upper end and a discharge outlet at the lower end of the said casing, and meansfor controlling the said passage by varying the free section thereof adjacent the circumferentially extending nozzle of the conical fuel sprayer.

13. In a carburetor for internal combustion engines, the combination of a casing having an inner wall substantially in the form of a frustum of an inverted cone, a hollow fuel sprayer substantially inthe form of an inverted cone coaxial with the said casing and leaving between itself and the inner' wall of said casing a passage extending substantially all around the said conical fuel sprayer and having an air inlet at the upper end and a discharge outlet at the lower end of the said casing, the said conical fuel sprayer being provided substantially at its widest portion with a circumferentially distributed nozzle opening into the said passage, and the diameter of the conical fuel sprayer at the said nozzle being materially greater than the diameter of the conical inner wall of the said casing at the discharge outlet thereof, a valve sleeve mounted in thesaid casing coaxially therewith and axially adjustable relatively thereto for controlling the said air passage by varying the free section thereof adjacent the said nozzle of the conical fuel sprayer, means for supplyingy fuel to the said nozzle, said means including a float chamber surrounded by the said hollow fuel sprayer, a float in said float chamber and a fuel supply valve controlled by the said float, and means connecting the said float to the said valve sleeve so that the float through this connecting means is positively moved downwards in the float chamber when the said valve sleeve is adjusted in the direction of opening it.

14. In a carburetor as claimed in claim 13 the further feature that the said valve sleeve is tem being housed in the upper part of the floatv chamber and being connected to the oat.

15. In a carburetor as claimed in claim 13 the further feature that the means connecting the said float to the said valve sleeve includes a link and lever system in which a spring is so connected that this spring is tensioned and exerts an increasing lifting power on the oat when' the said valve sleeve is moved in the direction of closing it.

16. In a carburetor as claimed in claim 13 the further feature that the float chamber communicates with the nozzle through a central opening in the bottom of the float chamber and a passage formed between the bottom of the oat chamber and the bottom ofthe hollow fuel sprayer, a needle valve controlling the said central opening in the bottom of the oat chamber and connected to a pressure reactive means exposed to the vacuum in the discharge outlet of the carburetor and automatically adjusting the said needle valve in accordance to the said vacuum, the means connecting the float with the said valve sleeve including a link and lever system a lever of which engages, lwith a certain play, the spindle of the said needle valve for limiting and adjusting the range within which the needle valve can be automatically adjusted in accordance to the said vacuum, a lever of the said link and lever system preferably having an adjustable pivot. y

17. In a carburetor for internal combustion engines, the combination of a casing having an inner wall substantially in the form of a frustum of an inverted cone, a oat chamber mounted on the said casing and having a lower part coaxial with the said casing, a hollow fuel sprayer substantially in the formv of an inverted cone and comprising an upper, annular part and a conical lower part both surrounding the lower part of the oat chamber and secured thereto, said upper and lower parts leaving bef" tween themselves substantially at the widest portion of the fuel sprayer a nozzle slot extending substantially all around the circumference of the fuel sprayer and inside the said nozzle slot an annular, preliminary mixing chamber having air inlet openings provided in the upper part of the fuel sprayer and a fuel inlet extending substantially all around the said lower part of the float chamber and communieating therewith, the said casing and fuel sprayer providing between themselves a main air and mixing passage of annular cross section, said passage having a circumferentially disposed air inlet at the upper end and a discharge outlet at the lower `end of the said casing, means for controlling the said passage by varying the free section thereof near the upper end of the said casing, ahood surround- -ing the said circumferentially extending air inlet, andair purifying means associated with said hood.

18. In a carburetor for internal combustion engines, the combination of a substantially conical, hollow fuel sprayer, an enclosing, substantially conical casing forming together with the said fuel sprayer an air and mixing passage of annular cross section, having a circumferentially disposed air inlet at its widest end and merging into a discharge outlet-formed by the said casing at the opposite end thereof adapted to be connected to the intake manifold or suction conduit of the engine, the said conical fuel sprayer being provided near its widest portion with a circumferentially distributed nozzle opening' into the said passage near the air inlet end thereof,\

and the diameter of the said substantially conical fuel sprayer at the said circumferentially distributed nozzle being materially greater than the inner diameter of the enclosing casing at the discharge end thereof, means for controlling the said air and mixing passage by varying at will the free section thereof adjacent to the circumferentially distributed nozzle of the fuel sprayer between said nozzle and the discharge outlet of the said passage, whereby to regulate the working of the engine, a liquid fuel chamber, means for conducting liquid fuel from said liquid fuel chamber to the said nozzle of the fuel sprayer, and means for automatically varying the fuel supply from the said liquid fuel chamber to the nozzle in dependence upon the conditioning of the working of the engine.

19. A carburetor according to claim 18 characterized in that the diameter of the fuel sprayer at vthe circumferentially distributed nozzle is approximately twice as large as the internal diameter of the carburetor casing at the discharge end.

20. A carburetor according to claim 18 characterized in that the crosssectional area of the annular air and mixing passage at the nozzle ofthe fuel sprayer is approximately equal to the cross sectional area of the passage at the discharge end of the carburetor casing when the means for controlling the said passage is set to fully open position.

21. A carburetor according to claim 18 wherein the air inlet is located at the upper end of the carburetor to permit the down draft of air undergoing carburetion.

AXEL HUGO WEIERTz. y PER AXEL REINAR WEIERTZ.