US3591148A

US3591148A - Carburetor

Info

Publication number: US3591148A
Application number: US859125*[A
Authority: US
Inventors: Hugo Schmitz
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-09-28
Filing date: 1969-12-18
Publication date: 1971-07-06
Anticipated expiration: 1988-07-06
Also published as: FR2019124A1

Abstract

A carburetor for motor vehicle internal combustion engines in which an annular atomizing chamber is formed between two axially aligned circular walls which are axially slidable relatively to each other to vary the size of the atomizing chamber so that no individual throttle valve for the fuel mixture is required. The air for atomizing the fuel is conducted into the annular atomizing chamber by two axially aligned tubular conduits leading from opposite sides through the center portion of the circular walls where a spherical body is fixedly arranged and in whose hollow interior extends a needle-valve controlled fuel admitting tube, while fuel outlet apertures in the sphere discharge the fuel into the airstream which is caused to flow from the tubular conduits into the annular atomizing chamber through a short and narrow and adjustable passage formed between the surface of the sphere and the adjustable circular walls.

Description

United States Patent [72] Inventor HugoSthmitz \eubeckumerstrasse 102.

472 Beckum. herman |21| Appl No 859.125 I22] Filed Sept. 18. I969 [45] Patented July 6. 1971 [3 21 Priority Sept. 28. 1968. June 21. 1969 [33] Germany [311 P1776 156.7andP1931 642.8

[54] CARBURETOR 15 Claims, 6 Drawing Figs. [52] US. Cl 261/29, 261/79, 261/39, 261/44, 261/69. 261/62, 261/51 [51] lnt.Cl F02m 9/10 [50] Field of Search 261/29,

3,286,997 11/1966 Ledbctlerm v. 261/79 X 3,336.017 8/1967 Kopa .1 1 261/79 X FOREIGN PATENTS 1.251832 2/1961 France. 261/79 Primary Examiner-Tim R. Miles Attorney-Singer, Stern and Carlberg ABSTRACT: A carburetor for motor vehicle internal combustion engines in which an annular atomizing chamber is formed between two axially aligned circular walls which are axially slidable relatively to each other to vary the size of the atomizing chamber so that no individual throttle valve for the fuel mixture is required. The air for atomizing the fuel is conducted into the annular atomizing chamber by two axially aligned tubular conduits leading from opposite sides through the center portion of the circular walls where a spherical body is fixedly arranged and in whose hollow interior extends a needIe-valve controlled fuel admitting tube, while fuel outlet apertures in the sphere discharge the fuel into the airstream which is caused to flow from the tubular conduits into the annular atomizing chamber through a short and narrow and adjustable passage formed between the surface of the sphere and the adjustable circular walls.

PATENTEUJUL 61971 3.591.148

sum 1 OF 5 ,4 da /re s PATENIED JUL em: 3591, 148

SHEET 2 OF 5 FIG. 3

INVEN TOR Hugo S072 mil? PATENIEU JUL 5:971

SHEET 3 OF 5 m wh w q ma m WA u H BY W PATENIED JUL 6197! 59 1. 148

sum

5 or 5 FIG. 6

INVENTOR Hu 0 ,Srbmzi BY 9 A ttomeys CARBURETOR The invention relates to improvements in carburetors for the fuel of internal combustion engines.

lntemal combustion engines employ carburetors of the most different construction. All of these carburetors, however, have in common that an air stream which is conducted past the end of a nozzle will draw fuel from the nozzle and this fuel, in view of the low pressure and the speed of the air, is atomized. There exists, however, a relationship between the aspirated amount of fuel and the amount of air passing the nozzle or between the low pressure at the nozzle which is proportionate to the amount of air. In the event that the cross section of the atomizing zone is not variable, the quality of the fuel preparation is increased or drops in relation to the intermingled amount of air or the speed of the air respectively. Devices are known in which these facts are properly considered, and which operate with an approximately constant low pressure in the atomizing zone.

in carburetors of this type the tube cross section above the fuel nozzle is regulated by a slidable piston which is in connection with a low pressure chamber in such a manner that when the low pressure increases the piston is raised so that the piston exposes a larger area of the cross section of the tube. At a reduced low pressure the piston drops correspondingly and the size of the free flow cross-sectional area in the atomizing zone is reduced. The piston has secured thereto a conical nozzle needle which follows the slidable movement of the piston and opens the fuel nozzle more or less. The control of the low pressure or the intermingled amount of air, respectively, is effected by a throttle flap arranged after the atomizing zone. This throttle flap regulates the size of the free flow cross-sectional area.

The disadvantage of these known devices, among others, is that the fuel is supplied point-shaped and, therefore, it can be treated only linearly in the direction of the stream of air. in addition, the throttle flap, which is arranged immediately after the atomizing zone, splits the air stream into two partial streams so that, dependent upon the position of the throttle flap and the piston, the fuel in one or the other pressure streams is given preferential treatment. This nonuniform distribution of the fuel in the air stream can also not be completely eliminated by a turbulence behind the throttle flap. The fuel introduction from the nozzle into the airstream and the further path of the fuel particles in the airstream corresponds, when considered according to the flow technique, to a combination of source and parallel flow. (See Eek, Technical Flow Science, th Ed., FIG. 58, Page 57.)

The heretofore known carburetor constructions may produce an approximate uniform low pressure in the atomizing zone, but they fail to produce a uniform distribution of the fuel in the airstream which is necessary to attain an optimum exploitation of the fuel and for reducing the heretofore customary CO contents in the exhaust gases of motor vehicles.

With a constant low pressure alone in the atomizing zone the problems of the known carburetor constructions are not eliminated. Around the throttle flap, which is arranged directly after the atomizing zone, are grouped a number of additional difficulties. The throttle flap, which is arranged in the prepared fuel-air mixture, first of all, separates the fuel-air mixture into two partial streams which, as a rule, can hardly contain each the same amount of air-fuel mixture. Regardless of the opening condition of the throttle flap, there will always be caused a back pressure in the stream with an unsymmetric secondary flow and secondary turbulences which are effective far into the air funnel and, therefore, prevent a uniform distribution of the fuel over the entire cross section of the stream. As a result of the produced unsymmetrical turbulences, which are particularly pronounced when the throttle flap is only partially open, the fuel particles are thrown against the wall of the conduit and this leads to the well-known fuel film on the wall of the suction conduit. It is obvious that this fuel film consists predominantly of the heavier atomizable particles of the fuel. When the throttle is closed, this fuel film evaporates in view of the suddenly increasing low pressure. Owing to the lack of air, however, only an incomplete combustion of the fuel takes place, with the result that the exhaust gases contain very high amounts of CO.

it is an object of the invention to eliminate the disadvantages of the heretofore known carburetor constructions and to produce a carburetor system in which the preparation of the fuel does not take place linearly in the direction of the flow of the air (two-dimensional) but takes place spatially, namely, three-dimensional.

At the same time, the system of the present invention is provided with regulating and dosage devices which pennit a regulation of the amounts of combustion air and the fuel entering the motor without employing a throttle flap in the mixing tube that is, the motor output is not regulated by the amount of the mixture by a direct regulation of the amount of the combustion air when the same still is without fuel.

The air is the carrier agent for the fuel. If the combustion engine has to deliver a predetermined output at the highest ex ploitation of the fuel, it is necessary to mix with the fuel a predetermined amount of combustion air, whereby the fuel has to be in a gaseous condition. Therefore, the air has not only the purpose of conveying the original fluid fuel in any manner to the combustion chamber, but the air also has to convert the fuel into a gaseous condition and must uniformly distribute the fuel in the combustion air and then has to be conducted to the combustion chamber of the internal combustion engine. In order not only to atomize the original fluid fuel but to also vaporize the same, substantially larger specific exchange surfaces are required between the combustion air and the f uel than are available in the conventional carburetors or in injection devices.

The realization of large specific interchange surfaces between the combustion air and the fuel presupposes that the air and fuel molecules are able to react with each other in a multilayer manner; that is their direction of movements and their speeds temporarily do not coincide with each other. This may be accomplished by a source of turbulence for the combustion air which, in the neighborhood of the core of the turbulence, is supplied with liquid fuel from a plurality of apertures. The centrifugal forces which decrease from the inside toward the outside and which also cause a decreasing angular speed of the airstream from the inside towards the outside act first of ali, upon the fluid particles of the fuel in the manner of a multilayer shear stream and cause a very quick droplet resolution which is followed by a diffusion of the fuel molecules so that a genuine spatial atomization of the fuel takes place.

Insofar as it is necessary for a fuel atomization to supply for the atomization thereof an additional amount of heat energy, this requirement can be met without difficulty since the required heat potential is obtained by the thermic motor process. The proportionate evaporative cooling effect obtained by the improved atomization prevents a temperature rise of the fuel mixture and no loss of charge is experienced by the motor cylinder.

Once the fuel is atomized, no danger exists any more that the fuel in the suction lines leading to the motor will again separate from the combustion airstream. The atomization of the fuel which already takes place in the carburetor has the additional advantage that the individual motor cylinders are supplied with a specific uniform mixture so that as a result the average specific engine output is improved. A further result of the improved atomization and the resulting improved combustion is a reduction of the toxic portions in the exhaust gases of the motor.

The drawing illustrates a few embodiments of carburetors constructed in accordance with the invention.

IN THE DRAWINGS FIG. I illustrates a longitudinal section of a carburetor having a rotational symmetric construction.

FIG. 2 illustrates across section along the line 2-2 of PK}. 1.

FIG. 3 illustrates one embodiment for the formation of a surface on a boundary wall for obtaining a substantial wall turbulence and for preventing the formation of a fuel film on the wall.

FIG. 4 illustrates another embodiment of the carburetor of the invention.

FIG. 5 illustrates an embodiment of the carburetor of the invention intended for an automatic adjustment of the feed of the fuel in relation to the supplied amount of air, and FIGv 6 il lustrates a carburetor in accordance with the invention which is provided with a special air supply device.

Referring to the FIGS. l and 2, the air enriched with fuel leaves the carburetor outlet 23 and is sucked in by the motor. The air, when entering the carburetor, passes through the filters arranged on opposite sides of the carburetor housing and then passes through guide vane rings 2i and with a twist enters the axially aligned suction tubes 26. When the air paaes the centrally disposed displacement body 12 at the inner ends of the tubes 26, it carries with it the fuel which is supplied by the nonles l3 and the fuel is thereupon atomized in the annular chamber or tunnel 29, which extends concentrically about the common axis of the tubes 26 and is formed between two circular walls 2. The discharge of the fuel through the nozzles 13 is supported by the low pressure created on the surface of the displacement body l2 and also by the superpressure existing in the interior of the displacement body 12 which, to a small extent is produced by the straight flowing airstream. The mixture of fuel and air flows in the annular chamber 29 or tunnel along spiral-shaped paths. ln view of the centrifugal forces which decrease from the inside to the outside, and also in view of the outwardly decreasing angular speed of the air, large specific interchange surfaces or larger relative speeds are produced between the fuel particles and the air particularly when the contact area of the walls 2 is provided with a series of concentric steps 2a. This results in a particularly effective preparation of the fuel. The better, however, the fuel preparation, the less danger filllSln that later on the fuel will separate from the air in the suction line of the motor.

in order to attain for a predetermined cross section of the passage for the required airstream in the atomization zone, the invention provides that the circular boundary walls 2 forming the annular chamber 29 are made adjustable so that the size of the cross-sectional passage is adjustable from a value zero up to a maximum value so that the fuel feed may be adjusted in relation to the amount of air in the airstream. This adjustment can be accomplished by purely mechanical means as it is illustrated in the FIGS. 1 and 2. The adjustment may, however, also be made in relation to the low pressure or in relation to the speed of the air at a point of the conduits which is suitable for measuring.

In the device illustrated by way of example in the FIGS. 1 and 2 of the drawing, the fuel is supplied by a not illustrated fuel pump which is connected to a pipe 9 leading to the fuel chamber 22 of the carburetor. This fuel chamber 22 is pro vided with an overflow regulator ll which permits the return flow of fuel by a pipe to leading to a suction line between the fuel supply container and the fuel pump. The nozzle tube 6 is rigidly connected to one of the circular walls 2 of the annuiar chamber 29 and therefore is slidably adjusted with this wall 2. The inlet end 7 of the tube 6 is conically enlarged and extends into the fuel chamber 22. The cone-shaped inlet end 7 serves as accelerating pump when a quicker gas supply for the motor is required. By means of a jerklike rearward movement of the cone 7, which extends into a small chamber 8, a short superpressure is produced in the chamber 8 which results in an accelerated feed of fuel into the hollow displacement body 12 having a substantially spherical shape. An intermediate space is formed between the cone 7 and the outer boundary wall of the fuel chamber 22 so that the fuel, even when the cone 7 is erked rearwardiy, may flow freely into the nozzle tube 6.

The amount of fuel which flows toward the nozzle tube 6 requires a basic adjustment. This adjustment can be accomplished in various ways. First of all, with the assistance of the overflow device II which regulates the return flowing fuel. The more fuel is returned, the less fuel reaches the nozzle tube 6. This overflow adjustment may also take place in relation to an opening condition of the annular chamber 29 and also may take place in relation to the opening condition of the nozzle outlet aperture in the displacement body 12 and also may take place in relation to the low pressure or the speed of the air at a suitable measuring point.

If, in view of sealing problems, one prefers to omit the axial displacement of the nozzle tube 6, then this tube 6 may be rigidly secured to the fuel feed device. The fuel dosing then takes place by slidably adjusting the regulating needle 14. The opening condition of the nozzle tube 6 may also be adjusted in relation to the opening condition of the annular chamber 29 for which purpose customary means may be employed or it may also take place in relation to the low pressure or the speed of the air at a suitable measuring point. The embodiment of the invention illustrated in the FIGS. 1 and 2 is provided with a mechanical adjustment of the nozzle needle 14 in relation to the opening condition of the annular chamber 29. When the lever system 3, 24, is operated it rotates the circular walls 2 about their tubular pivots which rotate in coarsely pitched threads 4 between the pivots and the correspondingly threaded apertures in the walls 5 of the housing. This has the result that the circular boundary walls 2 are selectively axially adjustable toward and away from each other and this results in an adjustment of the size of the cross section of the annular chamber. At the narrowest point the adjustment of the passage formed between the body 12 and the walls 2 has a value which is zero and this value may be increased to a maximum value. A shaft 30 is connected with the lever system 3, 24 and is provided with a pin l9 which, in turn, actuates a cam disc 27 for operating the lever 28 which performs an axial displacement of the nozzle needle 14 in the plane of the drawing. The needle 14 is slidably mounted in a tube 15 and the rear end of the needle 14 extends into a cylindrical casing 18 containing a helical spring 17 which surrounds the needle 14 and is arranged between the bottom of the casing 18 and a disc [6 fixedly attached to the needle 14.

The pitch of the cam disc 27 conforms to the different opening conditions of the annular chamber 29 and to the amounts of air which are permitted to flow into this chamber 29 so that a slidable adjustment of the nozzle needle 14 in the nozzle tube 6 controls the amount of fuel which is required for the respective amount of air.

In order to avoid any sealing problems which may arise at the sliding faces of the boundary walls 2 and the circumferential wall I, the present invention provides a further development in which the boundary walls 2 are made of an elastic material or at least made partly of such elastic material. The walls are then rigidly secured with their outer perimeter to the circumferential wall 1. Suitable pressure rings on the rear faces of the boundary walls 2 having approximately a diameter which corresponds to the narrowest portion of the annular channel, are then employed for changing the cross section of the annular atomization zone 29.

The shape of the boundary walls is not limited to the one illustrated in the drawing in order to practice the invention. If desired, other cross-sectional forms may be employed, for instance, plane, concave, or convexly curved.

Referring to the embodiment illustrated in FIG. 4, 31 is a fuel supply line leading to the fuel pump 32 which conveys the aspirated fuel into the pipeline 33 and into the fuel chamber 4] of the carburetor. The fuel chamber 4! is provided with a device for keeping the pressure constant. A portion of the fuel flows through the return line 34 back to the suction side of the fuel pump 32.

Centrally between the two axially spaced and axially adjustable walls 44 is fixedly arranged a sphere 46. This sphere 46 is provided with nozzle apertures 50 for the fuel and also with air ducts 47. When operating the gas pedal the two walls 44, with the assistance of not specifically disclosed devices, are slidably axially adjusted so that the cross section of the flow passages 42 and 43 are continuously varied. The two elastic rings 45 on the outer circumference of the circular walls 44 seal the inner space of the carburetor against the housing wall.

The air required for combustion, after passing air filters, enters the carburetor housing at two oppositely disposed places A and enters with a twisting motion the interior of the carbu retor. The entering amount of air is determined by the size of the cross-sectional area 42 formed between the outer surface of the sphere 46 and the rounded inner faces of the walls 44. The nozzle apertures 50 open at the narrowest point of the flow passages 42. A small portion of the centrally entering air is conducted by the air ducts 47, owing to the back pressure, into the inner space of the sphere 46 and there takes with it the fuel which enters the sphere from feed pipe 40 and then combines again with the main airstream in the range of the flow passages 42.

The fuel dosing takes place with the assistance of the axially slidably mounted nozzle needle 49 whose slidable displacement is effected in a purely mechanical manner by part 48 in relation to the opening conditions of the two walls 44 or may also be effected with the assistance of known means in relation to the low pressure at a suitable measuring point, preferably in the central suction tube leading from the air filter to the carburetor.

The airstream revolving around the sphere distributes and atomizes, first of all, any liquid fuel still in the narrowest portion of the flow passages 42. A further resolution of any still present very small fuel droplets takes place in the cross'sectional area 43. At this point the two partial streams come together. They revolve as a total stream between the two walls 44 about the axis of the carburetor and at the point B they are drawn lengthwise into the suction pipes which lead to the combustion chambers of the motor.

In view of the centrifugal forces within the revolving stream which decrease from the inside outwardly and in view of the likewise decreasing angular speed of the stream of the fuel particles from the inside outwardly, the air acts as a multilayer shear stream so that a complete resolution of the fluid fuel takes place and an absolute homogeneously prepared fuel-air mixture is produced which leaves the carburetor at B. This homogeneously prepared fuel-air mixture can not be brought to dissociation because it is gaseous, even when subjected to periodic oscillations of the air column in the suction conduit, so that all the individual combustion chambers are provided with a qualitative uniform mixture which improves the allover efficiency of the motor.

The atomizing principle of the invention, in addition to the advantages of an improved fuel atomization, has additional advantages in constructural regard and in the fuel control technique. The control possibilities produce an improved torque characteristic and also a favorable CO emission of the motors installed in motor vehicles, whereby always an optimum relation is automatically maintained between the amount of air necessary for combustion and the amount of fuel thereby assuring at the same time genuine vaporization of the fuel.

in the embodiment of the device of the invention as illustrated in FIG. 5, the regulation of the fuel feed or the slidable adjustment of the fuel regulating needle 49, respectively, is ac complished with the assistance of a measured value transducer 51. The amount of air passing through the filter 52 is measured in the central suction tube between the air filter and the carburetor at 53 or a measured value equivalent to the amount of air is entered into the measured value transducer 51 which in turn transmits regulating pulses corresponding to this measured value to the fuel dosing device. The measured value transducer 5] may also consist of a pneumatically actuated adjustment member or may consist of an electronic computer with an attached mechanical adjustment member which in addition to the measured value which is equivalent to the the amount of air, considers additional factors which influence the operation of the motor, such as the temperature, barometric pressure, humidity and the like, and transmits correspondingly corrected control pulses to the fuel dosing device. In similar manner, the shut-off of the fuel feed takes place when the vehicle is decelerated and an enrichment of the fuel mixture takes place with the assistance of the measured value transducer when the motor has to start when it is cold.

In the embodiment of the device illustrated in FIG. 6, a mechanically driven air blower is arranged in front of the carburetor which eliminates any charge losses resulting from fuel flow losses at full load.

The air drawn in at 54 and passing through the filter 52 is accelerated or receives a pressure increase by the rotor 56 driven by a motor 55. An adjustment flap 59 causes a more or larger portion 58 of the airstream 57 which leaves the rotor casing, to flow through a bypass tube 60 back into the filter 52. If now the pedal 61 is depressed, the adjusting flap 59 is closed, the bypass tube 60 is also closed so that a larger amount of air can flow to the carburetor. The amount of air which is conducted into the carburetor, or its equivalent measured value taken at 53, is converted by a measured value transducer 51 into an adjusting pulse and is transferred to the fuel regulating needle 49 and to a mechanical adjustment member 62. The fuel regulating needle doses the fuel feed proportional to the amount of air passing through the carburetorv The mechanical adjustment member 62 acts upon the levers 63, 64 and 65 and upon the adjustable walls 44 shown in FIG. 4 in such a manner that the same are axially slidably adjusted and adjust the size of the passage 42 to such a value that the speed of the air in this passage is independent of the amount of air and is always approximately constant.

The mechanical adjustment member 62 may also be con structed in such a manner that it operates directly in proportion to the air pressure at 53 in order to effect an adjustment of the walls 44.

The rotor 56 assists the pistons of the engine to draw the mixture into the combustion chambers and this assures a substantially improved filling of the cylinders particularly at full load compared with a device in which the fuel mixture is solely drawn into the cylinders by the low pressure produced by the downward moving pistons.

What I claim is:

l. A device for preparing atomized fuels, comprising a housing, means forming in said housing a variable atomization zone comprising an axially symmetrical structure including two parallel walls forming between the same an annular tunnel for receiving the atomized fuel, means for connecting said atomization zone with an air supply means, means for adjusting the cross section of said atomization zone in relation to the amount of fuel required, means for feeding separately air and fuel to the center of said atomization zone, and means for tangentially discharging the prepared atomized fuel from said annular tunnel, said means for adjusting the cross section of said atomization zone including at least one of said walls, means for axially adjustably mounting said wall, and means for axially adjusting said wall relatively to the other for changing the cross section of said atomization zone.

2. A device according to claim 1, including means for regulating the amount of fuel which is introduced centrally into said atomization zone in relation to the adjusted size of crosssectional area of said annular tunnel.

3. A device according to claim I, including means for regulating the dosage of said fuel which is centrally introduced into said atomization zone in relation to the low pressure in said zone.

4. A device according to claim 1, including means for regulating the dosage of said fuel which is centrally introduced into said atomization zone in relation to the amount of air passing through said zone.

5. A device according to claim I, in which the means for supplying fuel to the center of said atomization zone is provided with means for returning some of said fuel to the place of supply in relation to the amount of air required for atomization of the amount of fuel in said atomization zone.

6. A device according to claim I, in which at least one of said axially adjustable walls is provided with an annular elastic portion which is fixedly connected to a circumferential wall of said housing of said carburetor.

7. A device according to claim 1, including a hollow displacement body arranged between said two walls at the center thereof, means for supplying fuel to the interior of said body, said body being provided with a nozzle aperture communicating with said atomization zone.

8. Device according to claim 1, including means for regulating the amount of the prepared fuel mixture which is conducted to an internal combustion engine in relation to the pressure measured between the device and said engine.

9. Device according to claim 1, including a fuel dosing means and an electronic computer which in accordance with the amount of air passing through said annular tunnel produces a control pulse which actuates said fuel-dosing means.

10. Device according to claim 1, including a fuel-dosing means and an electronic computer which in accordance with the amount of air passing through said annular tunnel produces a control pulse which actuates said fuel-dosing means, said computer including means for rendering effective other factors such as temperature, barometric pressure and humidity which modify the atomized fuel which is tangentially discharged from said annular tunnel.

ll. Device according to claim 1, including a fuel dosing means and an electronic computer which in accordance with the amount of air passing through said annular tunnel produces a control pulse which actuates said fuel-dosing means, said computer including means for controlling the ad mission of an additional amount of fuel required for starting a cold engine and also being adapted to close down the feed of fuel when the engine is to be made inoperative.

12. A device according to claim 1, including a mechanically operated air blower connected with said air supply means.

13. A device according to claim I, including a mechanically operated air blower connected with said air supply means, the output of said blower being connected with an air input tube leading to said atomization zone, and a valve controlling a branch pipe leading from said air output tube to the input side of said blower, said valve controlling said branch pipe being adjusted by a manually operable foot pedal.

14. A device according to claim 1, including means for axially adjusting said two walls relatively to one another in relation to the low pressure produced by the air admitted to said atomization zone at the point where the fuel is introduced into said zone.

15. A device according to claim 1, including means for axially adjusting said two walls relatively to each other in relation to the amount of air admitted into said atomization zone.

Claims

1. A device for preparing atomized fuels, comprising a housing, means forming in said housing a variable atomization zone comprising an axially symmetrical structure including two parallel walls forming between the same an annular tunnel for receiving the atomized fuel, means for connecting said atomization zone with an air supply means, means for adjusting the cross section of said atomization zone in relation to the amount of fuel required, means for feeding separately air and fuel to the center of said atomization zone, and means for tangentially discharging the prepared atomized fuel from said annular tunnel, said means for adjusting the cross section of said atomization zone including at least one of said walls, means for axially adjustably mounting said wall, and means for axially adjusting said wall relatively to the other for changing the cross section of said atomization zone.

2. A device according to claim 1, including means for regulating the amount of fuel which is introduced centrally into said atomization zone in relation to the adjusted size of cross-sectional area of said annular tunnel.

3. A device according to claim 1, including means for regulating the dosage of said fuel which is centrally introduced into said atomization zone in relation to the low pressure in said zone.

5. A device according to claim 1, in which the means for supplying fuel to the center of said atomization zone is provided with means for returning some of said fuel to the place of supply in relation to the amount of air required for atomization of the amount of fuel in said atomization zone.

6. A device according to claim 1, in which at least one of said axially adjustable walls is provided with an annular elastic portion which is fixedly connected to a circumferential wall of said housing of said carburetor.

11. Device according to claim 1, including a fuel dosing means and an electronic computer which in accordance with the amount of air passing through said annular tunnel produces a control pulse which actuates said fuel-dosing means, said computer including means for controlling the admission of an additional amount of fuel required for starting a cold engine and also being adapted to close down the feed of fuel when the engine is to be made inoperative.

13. A device according to claim 1, including a mechanically operated air blower connected with said air supply means, the output of said blower being connected with an air input tube leading to said atomization zone, and a valve controlling a branch pipe leading from said air output tube to the input side of said blower, said valve controlling said branch pipe being adjusted by a manually operable foot pedal.