DE2110506C3 - Carburetors for internal combustion engines - Google Patents

Description

) ic invention relates to a carburetor for nnkraftmaschinen with an air intake line. in an arbitrarily changeable in its cross-section,. annular Engstellc is arranged, which the Nutrient can be supplied in appropriate quantities, and a gradually increasing cross-section dust part connects.

Such a carburetor is known from US-PS 19 73 362. This known carburetor is designed so that an axially adjustable air throttle member is provided in the intake duct for setting the free flow cross-section *. The position of the air throttle element in the intake channel depends on the position of the accelerator pedal: inside the air throttle element, which is tapered in the lower area. there is a float chamber and a fuel measuring device which adapts the fuel cross-section to the air throughput depending on the position of the air throttle element. The fuel is supplied via an annular groove on the air throttle element. which is arranged at the point of the smallest distance to the wall of the intake duct. In this way, a particularly uniform distribution of the fuel in the air flowing through the narrow cross-section is to be achieved.

In this known carburetor , although the downstream increasing distance between the air throttle element and the wall of the intake duct is referred to as Zers'.aubteil, on the other hand, however, the known carburetor aims at such a design. in which, unlike throttle valve carburetors, the suction pressure of the internal combustion engine is opposed as little resistance as possible, so that the cylinder of the internal combustion engine is better filled with the explosive fuel / air mixture. For this purpose, the arrangement between the air throttle element and the intake duct should be such that, for example, when the flow cross-section is fully open, i.e. at full throttle, the air passage area adjacent to the annular groove supplying the fuel, and thus at the annular constriction, should be as large or even larger than the free one Cross-section of the intake line itself. It can be seen that with such a design an atomizer part having a tapering in the intake area cannot be obtained (see page 1, lines 46 to 60 and p. 2, lines 70 to 77 of this US Pat. No. 19 73JG2 ).

Other carburetors for internal combustion engines that are im The intake duct also has an air throttle element which can be adjusted axially relative to it, are known, for example from FR-PS 15 18 991. du-FR-PS 15 79 278 or DL-PS 387; with all of these known The carburettor is the one that arises when the throttle valve that is always present suddenly opens Avoid pressure drop in the intake port, as this will lead to an increase in engine power instead Waste results because, due to such a sudden transition, a fuel-lean mixture adds to the engine flows in. The mixture feed is determined in these, as in all other previously known carburetors due to the negative pressure prevailing in the intake duct, which means that the for the respective Amount of air required amount of fuel adjusts essentially automatically.

By arranging an air throttle element which then necessarily forms a constriction with the intake duct it is possible to prevent an abrupt drop in pressure, because the adjustment of the air throttle element takes place automatically depending on the respective negative pressure in the intake duct. These are Systems that react to the negative pressure are provided.

Due to the automatic adjustment of the air funnel cross-section every time the throttle valve is actuated, a smooth and flawless operation is achieved

Transition from idling to maximum engine output without additional accelerators. With the DL-PS 387, in the part load range, is the fuel supply system in the same way as the actuation of the Throttle valve in connection that the flow of the: fuel through a special throttle nozzle in appropriate dosage can take place, this flow is also regulated by the itself automatically changing position of the air throttle device, but always only in the partial load range. ι ο

In the legends for completeness further carburettor be specified, which also grout respectively in the intake duct via means, can be subjected by means of which d ^ei \ free Strömu'igsquerschnitt of the intake duct of a change. All of these publications, however, have in common that the fuel supply reacts to the pressure prevailing at a certain point in the intake duct and attempts are made in this way to match the fuel-air mixture to the amount of air sucked in by the internal combustion engine. Variable curvature cross-sections refer to US-PS 27 11 884, DT-PS 3 75 121, the DT-PS6 26 755, the GB-PS1 94 842, which corresponds to the DTPS 3 85 425, the GB-PS 126 22b, the OE- PS 2,28,011 and U.S. Patent 2,332,716.

Finally, the publication by A. Pierburg "Carburetors for Motor Vehicle Engines", 4. Edition, 1970 on pages 31 and 32 as known that the maximum drop size in the Formation of a fuel-air mixture, apart from the material constants, strongly depends on the prevailing one Relative air-fuel speed depends. The relative speeds are known to be one Function of the pressure differences prevailing in the carburetor, which is then almost as a result of idling closed throttle valve and the resulting sickle-shaped gap pressure differences can build that allow speeds equal to the speed of sound. However, the the resulting advantage of fine atomization is impaired by the proximity of the flow to the wall, since high wall precipitation occurs.

Finally, two other publications should be mentioned, namely the book »Introduction to the technical thermodynamics «by E. Schmidt, edition 1953, especially page 279, and the book "Rocket Propulsion", 1952, by Eric Burgess, Chapman and Hall Publishers, London, pages 78 and 79.

The book "Introduction to Technical Thermodynamics" shows the representation of a Laval nozzle on the mentioned page with a diagram below that indicates the static pressure along the axis of the Laval nozzle at different back pressures at the end of the Laval nozzle. In addition, as stated, for example, on pages 264 and following of this publication, it is known that the speed of a flowing medium at a constriction is a function of the pressure difference prevailing there. where for air, for example, the speed of sound of the air flowing through the constriction exists when the so-called critical pressure ratio is reached. If one disregards other variables, the critical pressure ratio is about 0.54. Is the Laval nozzle shown in Fig. 167 on page 267 of this publication _{6 <j} certain way formed, that is, the opening angle of the Diffuserteils formed is within predetermined values, then the Engquerschnittes is also achieved the speed of sound in the area, when the back pressure at the end Laval nozzle is not in the critical pressure ratio with the inlet pressure.

Finally, on page 79 of the publication "Rocket Propulsion" there is an indication of the angle between 6 and 12 °, for which opening angle in a Laval nozzle the critical pressure ratio can be achieved.

The disadvantage of all previously known carburetors is that they are only suitable for a certain one Let the operating range be optimally designed and that for considerably different engine running conditions such as idling, acceleration, full throttle and coasting operation additional elements are required. But even then Known carburetor designs are not able to run the engine in all running conditions to supply the desired fuel-air mixture in the desired ratio.

This leads to large differences in the fuel-air mixture from cylinder to cylinder of the engine and from work cycle to work cycle, even if the metering function of the carburetor is initially the desired one Fuel-air ratio at the inlet of the intake manifold results. The reason is that the Mixing function, despite many improvements, is so bad that flows of liquid fuel up get to the intake manifold, whereby the walls of the intake manifold partially wets and in certain Even pools of liquid fuel can accumulate in areas. It can be seen that on this Correct combustion cannot be achieved, as some cylinders are too rich and others are too rich Under certain circumstances, a mixture that is too lean is obtained, the terms too rich or too lean here referring to the roughly stoichiometric combustion air ratio, at which 15.5 parts of air come to a fuel.

Particularly disadvantageous in this context is the incomplete combustion or by polluting exhaust gases produced by other influences, which essentially consist of unburned hydrocarbons, Carbon monoxide (CO) and nitrogen oxides (NO «) exist.

The following explanations are intended to provide some additional information regarding the exhaust gas proportions close. So had before the introduction of the American federal and state standards for permissible exhaust gases normal automobile engine in good running condition in normal operation an average of about 900 ppm hydrocarbon, 3.2% CO and 1200 to 1500 ppm NO «generated. Also in the following The abbreviation »ppm« used means »parts per million«. The American federal standards imposed in the January 1968 came into force, dealt .iur with hydrocarbon and CO levies and continued as upper limit for a prescribed cycle test with seven operating modes, the so-called California cycle, the typical 20-minute drive of a vehicle from cold start through city traffic to full operating heat is simulated on the dynamometer, 2.1 g / km hydrocarbon and 22 g / km CO, what about 275 ppm hydrocarbon and 1.5% CO in the average American automobile is equivalent to. From January 1970 these values were reduced to 1.4 g / km hydrocarbon and 14 g / km CO, which corresponds to about 180 ppm hydrocarbon and 1% CO.

In 1973, as a result of the American federal standards, NO _{1 is also} reduced to 1.9 e / km, and im

In 1975 the permissible exhaust gases were drastically reduced again to 0.31 g / km hydrocarbons, 6.8 g / km CO and 0.56 g / km NO *. This corresponds to approximately 40 ppm hydrocarbon, 0.5% CO and 240 ppm NOx for an average automobile.

Vehicle engine manufacturers were able to meet emissions standards with some difficulty for 1968 must primarily be complied with by one or more of the following engine modifications were introduced:

1. Delay of pre-ignition

2. Recalibrating the carburetor to achieve lean air-fuel mixtures,

3. heating of the intake manifold,

4. reduction of valve overlap,

5. Increase in the ratio of stroke to bore,

6. Blowing air into the exhaust manifold and

7. Construction of cleaner combustion chambers.

Further improvements in these areas may also make the federal standards of 1971 possible to be met by 1974.

However, the stringent requirements of the 1975 emissions standards are such that it is believed that the The most favorable combination of all of the above-mentioned measures is not sufficient and it has been done seriously considered whether an internal combustion engine is made that pollution-free at all it can be ensured that these intended standards can be met.

The invention is therefore based on the object of improving said carburetor in such a way that such an air-fuel mixture is generated that a considerable reduction in all undesirable exhaust emissions is achieved.

To achieve this object, the invention is based on what is assumed to be known at the outset Carburetors and, according to the invention, consists of the combination of the following features:

a) that the formation of the atomizer part and its associated constriction is made so that over a substantial part of the speed and load range by maintaining the critical pressure ratio is present at the constriction of the speed of sound

b) that a fuel feed device is provided, the delivery rate of which is dependent on the change in cross-section of the bottleneck changes.

The invention is the first time a way that an extremely fine mixing and distribution of the liquid Fuel in the intake air allows So far this was considered impossible because of the Internal combustion engine assigned to the carburetor due to its intermittent operation at the end of the engine Intake channel with such different pressures depending on the respective operating conditions made available, d ^ B the achievement of the critical Air ratio in the carburetor area has not been possible In addition, changes when in the pressure assigned to this area prevails in a certain area of the speed of sound Dependence on the respective area of the flowing medium quantity no longer, so that no independent Adjustment and addition of the fuel to the amount of air flowing past the nozzle opening is guaranteed.

However, all known carburetor designs use the amount of air flowing past and the prevailing negative pressure itself given metering effect for the addition of the fuel in one or other form, d. i.e., the dosing effect is based on the suction effect of the internal combustion engine, which is within a rather coarse range sucks as much fuel out of the carburetor area as it approximates the desired, possibly corresponds to the stoichiometric ratio to the amount of air drawn in.

"o In contrast, the invention is based on the Realization that a perfect atomization, which also meets strict regulations, is only possible if this is the case can be achieved if the distribution of the engine is practically in the entire operating range of the engine Fuel in the amount of air supplied to the internal combustion engine in the maximum possible, finely divided Form takes place, that is, when the supplied fuel in air flowing past at the speed of sound is introduced. On the other hand, a specially trained fuel supply device is then required, which is no longer based on the negative pressure drawn in by the amount of air drawn in, Instead, it feeds the fuel depending on the cross-section of the constriction, because at the speed of sound of the air supplied to the constriction is only the cross section of the constriction for the Air volume responsible.

According to an advantageous embodiment of the invention, the increase in the cross-sectional area corresponds to the the atomizer part adjoining the constriction forms a cone with an opening angle of approximately 6 up to 8 °. This makes it possible to stay within a range in which the speed of sound at the Narrow point or, more precisely, the critical pressure ratio required for this, also in this area is given when the pressure conditions upstream and downstream of the constriction on the one hand and the atomizer part on the other changes within the broadest limits.

It is also particularly advantageous in the invention that the distribution of the fuel in the air takes place so finely and so evenly and homogeneously Mixture can be formed that no additional heat is required to evaporate the fuel and you can even work with fuel-air ratios in the order of 120: 1 or more, whereby the combustion in the individual cylinders always takes place with an excess of oxygen, which leads to a considerable reduction in pollutant emissions and of course also in fuel consumption On the other hand, despite such lean fuel-air mixtures, it is possible to also reduce the production of nitrogen oxides, since the combustion process due to the dei Formation of the fuel and air mixture supplied to the cylinders at lower temperatures, however At a higher speed, you also have requirements for the octane number of the fuel even with relatively high compression engines, it is considerably reduced

Finally, it is advantageous that the invention behaves in a manner that is inexpensive to manufacture and easy to install and < is to be maintained. It works trouble-free in order to be reliable.

Further refinements of the invention are the subject matter of the subclaims and are laid down in them.

In the following, the structure and mode of operation of an embodiment of the invention are based on de Figures explained in more detail. Show it

Fig. T is a schematic, perspective view of a device according to the invention, which is attached to a Intake manifold of an internal combustion engine is attached, which is indicated by dash-dotted lines,

2A and 2B enlarged schematic representations lungs of different designs of intake duct and constriction,

3 shows a vertical section through a first Embodiment of a carburetor,

4 and 5 sections along lines 4-4 and 5-5, respectively, of the | _O Fig. 3,

F i g. 6 shows a section similar to FIG. 3 by a second embodiment of a carburetor,

7 and 8 sections along lines 7-7 and 8-8 of FIG. 6,

F i g. 9 shows a plan view of a third embodiment of a carburetor, with individual parts in section are,

FIG. 10 is a partially sectioned front view of the illustration of FIG. 9 according to their cutting line 10-10,

Fig. 11 and 1 2 sections along line 11-11 and 12-12 of Fig.9 and

13 is a view from below in the direction 13-13 according to FIG Fig. 10.

In Fig. 1, a carburetor for mixing liquid fuel and intake air is schematically shown, the intake manifold 21 of a conventional gasoline or Otto engine indicated by dash-dotted lines is appropriate. The Otto engine shown there has six cylinders, but it should be noted that the carburetor 20 is in no way limited to use with such a motor. The invention can be broken down into Use advantageously on Otto engines with different numbers of cylinders and arrangements, for example for 2, 4, 6, 8 and 12 cylinders in line, in V-shape or in a boxer arrangement.

As is common with many in-line 6-cylinder engines, the inlets of the front, rear, and center pairs of cylinders are interconnected (the ^ ₀ cylinders are not shown). The illustrated intake manifold 21 thus has three branch lines 22 which each lead to the inlets of the respective pair of front, rear and central cylinders.

The carburetor 20 has one for the intake air serving channel 25, hereinafter referred to as air intake, which is provided with a device to adjustable to throttle the flow of intake air, reducing the speed of the same before the inlet the intake air into the intake manifold 21 is increased considerably. As in Fig. 1 shown is a Throttle member 26 is provided, which is concentric and relative to a converging constriction 27 of the Air intake line 25 is arranged axially movable. In a preferred embodiment, the movable throttle member 26 and the constriction 27 of the air intake line 25 essentially rotationally symmetrical, so that an annular outlet opening of variable cross-section is present between them is. However, other forms of throat can also be used.

In the F i g. 2A and 2B show two exemplary embodiments in order to narrow the outlet opening of the air intake line 25. As shown in FIG. 2A, the air intake line 25a has an upper constriction 27a with e <, a cross section that converges in the direction of flow. The location of the maximum narrowing of the air intake line 25a is defined here by the plane 28a which goes transversely through the air intake line 25a and below the air intake line has a channel section 29a of diverging cross-section. In this embodiment, the axially movable throttle member 26a is provided with a converging lower end piece which has an angle of convergence which is smaller than the angle of convergence of the constriction 27a of the air intake duct 25a. Since the converging constriction 27a of the air intake line and the throttle member 26a preferably have circular cross-sections, there is a variable annular outlet opening between them in the plane 28a.

In Fig. 2B, as shown schematically, the Lultansaugleitung 256 is also with an upper, upstream arranged constriction 276, viewed in each case with respect to the constriction, from in the downstream direction Converging cross-section provided, but here is the axially movable throttle member 26b with a converging lower end piece provided, whose angle of convergence is greater than the angle of convergence the constriction is 276. This arrangement ensures that the point of maximum constriction in the Air intake line 256 lies in a movable plane 286 through the furthest section of the throttle member 266 passes through and lies between the ends of the converging throat 276. It surrenders Furthermore, that due to the different angles of convergence of the throttle member 266 and the constriction 276 an annular section of divergent cross-section in the air intake duct 256 below the Level 286 is formed. The air intake line 256 is also preferably provided with a duct piece 296 of FIG diverging cross-section in the downstream direction relative to the converging channel piece 276 provided.

In Fig. 1, the throttle member 26 and the constriction 27 cooperate to constrict the flow of the intake air drawn in through the air intake line 25 so that there is a considerable increase in the velocity of the intake air before it enters the intake manifold 21. It should also be noted that during normal running of the engine the pressure at the intake manifold 21 is below atmospheric pressure, so that there is a vacuum in the manifold. In general, this vacuum is between 150 and 600 mm of mercury or in other words: between 0.2 and 0.8 kg / cm ² , depending on the engine speed and the load conditions. The vacuum in the intake manifold, however, can drop below 150 mm of mercury with rapid acceleration and can possibly exceed 600 mm of mercury with very rapid negative acceleration.

When the pressure in the intake manifold is 53% of atmospheric pressure, the intake air flow gets the speed of sound through the constriction formed between the throttle member 26 and the converging constriction 27. Since this occurs at manifold pressures of approximately 0.6 kg / cm ² or less, the result is that the intake air is increased to the speed of sound over a considerable part of the vacuum range in the intake manifold when the engine is running.

By gradually increasing the cross-sectional area of the air intake duct below the point of the At the maximum constriction in the constriction 27, an atomizer part is formed. Preferably the cross-sectional area increases with the distance from the constriction in a manner similar to that of a cone with a Point angles of about 6 to 8 degrees too. Such a

709 607/197

■ »i, ■

The atomizer part is in an exaggeratedly large form in both embodiments according to FIG. 2A and 2B. The gradual increase in the cross-sectional area through the atomizer part makes it possible to achieve a considerable Part of the kinetic energy of the high-speed intake air as static Regain pressure and thereby increase the range of vacuum conditions in the intake manifold, at which a speed of sound is achieved through the constriction.

According to an embodiment feature of the present invention, liquid fuel is in the Flow path of the intake air at the point of the maximum constriction in the constriction 27 of the carburetor 20 or previously introduced. As the intake air speeds up through the constriction, it becomes liquid Finely divided fuel and of the high speed, namely the speed of sound Intake air carried away. It was found that by increasing the air speed the constriction to the speed of sound a considerable and usable part of the finely distributed Fuel remains in the intake air on its way through the intake manifold and to the cylinders is taken. After the fuel has been distributed and taken along at the bottleneck, the speed the intake air and the fuel carried along by increasing the cross-section of the flow path reduced.

It was found that the usual Otto engine, which is provided with a carburetor 20, considerably lower values of undesired AbTable I

gas emissions are generated as the same Otto engine with a normal carburetor. For example, a Rambler American 220, born in 1963, with a 6-cylinder in-line engine of 3.2 liters and a compression ratio of 8.7: 1 checked for the existing exhaust emissions, this was once equipped with a normal single carburetor and to change a carburetor according to the Invention owned.

ίο The car was based on a standard Clayton chassis dynamometer tested, with normal road traffic attacking the rear wheels of the car. the Hydrocarbon exhaust emissions in parts per million have been steadily increasing at a non-dispersive rate Beckmann infrared spectrometer was measured, which was sensitized to hexane. The percentage of the free Oxygen in the exhaust was also constantly monitored using a Beckmann paramagnetic oxygen analyzer measured and monitored. The percentage of carbon monoxide in the exhaust became periodically point-wise checked with a Baberach carbon monoxide analyzer. A modified Saltzmann solution was made used to periodically determine the oxides of nitrogen in the exhaust in parts per million. A Comparison of the exhaust emissions of the car using a conventional carburetor and under Use of the carburetor according to the invention is shown in Table I when running the car with 48 and 8C Kilometers per hour shown. In all cases the data represent an average of the various n samples.

Coal CO% NO « O: "/ 0 hydrogen ppm ppm speed 48 km / h Normal ver 360 0.10 1750 4.2 gas Carburetor 35 0.27 395 b.2 Type a speed 80 km / h Normal ver 330 2.60 2500 1.5 gas Carburetor o ^# ) 0.10 305 5.7 Type a

·) Below the 30 ppm limit at which hydrocarbons could be reliably tested with this test device

It can be seen from the table above that the undesirable emissions of hydrocarbon. CO and NO. were considerably reduced and the percentage of free oxygen in the exhaust during the 80 km / h test was significantly increased. if the Car was equipped with a carburetor according to the invention. The values of hydrocarbon and NO »were also significantly reduced when the car was combined with a carburetor according to the Invention and had a speed of 48 km / h.

The carburetor of the invention used with the Rambler engine for the above investigations is shown in detail in FIGS. As shown there, the carburetor 30 has a Air intake line 31 with a constriction 32. which converges in the downstream direction to now the Stroi of the intake air through the constriction 32 further 2, is an axially movable throttle element:

arranged coaxially in the constriction. The Drosselglic 33 has a converging lower end piece 34, ie along with the lower end of the converging «

Constriction 32 forms a variable annular outlet opening 35 (see FIG. 5).

The intake air is dun in the air intake line 31 sucked in a line 36 which penetrates tangentially a deck 37 at the large end of the air duct. D. Intake air then flows through the Luftansaugleitui and the converging constriction 32, where the Stro is narrowed by the throttle member, so that c is the speed of the intake air before it passes through

through an exhaust line 38 and prior to entering the intake manifold of the engine. the Air intake line 31 has a diverging duct piece

39 in the downstream direction then to the place the maximum throat of throat 32. In this regard, carburetor 30 is substantially similar the carburetor according to FIG. 2A.

Liquid fuel is fed to the carburetor 30 according to FIGS. 3 to 5 via a fuel nozzle 40. In In this exemplary embodiment, the fuel nozzle 40 protrudes axially into the air intake line 31 with penetration of the cover 37 into it. The outlet end of the nozzle is in the middle of the air intake line at a considerable distance arranged above the point of maximum constriction of the constriction. The liquid fuel will preferably essentially symmetrically into the air intake line 31 from the outlet end of the nozzle sprayed. For this purpose the nozzle shown is

40 designed as a suction nozzle and has a baffle member

41 on. which is arranged at right angles to the discharge end of the nozzle so as to distribute the liquid fuel in a substantially radial direction. For the above-mentioned investigations, the nozzle was supplied with air at a pressure of about 2.8 kg / cm ² , and the flow of fuel through the nozzle was regulated by a valve, not shown.

Now to ensure that the liquid fuel is essentially symmetrical in the path of a high Intake air flowing through the constriction of the constriction 32 is introduced, the air intake line 31 and the constriction 32 are preferably essentially perpendicular with their axis oriented. With this arrangement, the liquid fuel sprayed from the nozzle 40 runs and reaches the inner wall of the air intake duct 31 and the constriction 32, downwards along the inclined Wall of the constriction essentially uniformly up to the area of the maximum constriction between the Constriction 32 and the throttle member 33. At the point of the maximum constriction (the one through the section line 5-5 the F i g. 3) the high velocity air grazes the liquid fuel film from the mouth wall, distributes it finely and charges the intake air with this fuel.

In order to control the size of the bottleneck in the carburetor and thus the flow of intake air through the To modify the narrow point through it, the throttle member 33 is axially movable. In the one shown in Fig.3 Embodiment, the throttle member 33 is arranged on a control rod 45 which is in an approach 46 of the Mixture line 38 is screwed in. There is also a knurled button 47 at the lower end of rod 45 provided so as to the rod for raising or lowering the throttle member 33 relative to the constriction 32 to be able to rotate and thus to increase or decrease the area of the outlet opening 35.

Another Ausfüh -ungsbeispiel a carburetor is in Fig. 6 to 8 shown. The carburetor 50 shown there is similar to the carburetor 30 according to FIG. 3 to 5. and it The same reference numerals are used around the air intake line 31, the cover 37, the tangential To designate suction line 36 and the nozzle 40. It should be noted, however, that the constriction 52 and the throttle member 53 in this embodiment of the schematic arrangement according to FIG. 2B and not after 2A follow. In other words: the maximum constriction in the form of an annular outlet opening 55. as between the narrowing 52 and the

Throttle member 53 is present, is not in a fixed Location, as in the exemplary embodiment according to FIG. 3, but arranged in a movable plane, the through the section line 8-8 in FIG. 6 is defined by the widest section of the conical lower End of the throttle member 53 passes therethrough.

It should be understood that the carburetor 50, as shown in FIGS. 6-8, has other means of lifting and lowering of the throttle member 53 at the constriction 52 compared to the carburetor 30 according to FIG. 3 has. the Device for raising and lowering has the form of a crank arm 54, on which the throttle member 53 by a tab 56 is suspended. The crank arm 54 is carried by a transverse shaft 57 which is the air intake duct 31 penetrates. Furthermore, a further crank arm 58 (see FIG. 7) is arranged at the end of the cross shaft in order to to move the throttle member 53. This arrangement not only allows convenient control of the Movement of the throttle member 53, but also allows a coupling of the throttle member position controlling Control linkage with a fuel valve, not shown, in order to control the quantities supplied to the engine to coordinate liquid fuel and intake air.

The carburetor according to FIGS. 6 through 8 was also used in the 1963 Rambler automobile, as noted above, checked. The results of the tests, which in turn contain average values from several samples, are in of Table II.

Table!!

1% 3 Rambler 220 with mixing device type B

speed
km / h

Hydrocarbon
ppm

CO%

NO,

ppm

O2%

40 24 30th 0.10 ·) 15th 6.8 32 0 *) 0.10 ") 10 5.8 56 0 0.10 *) 58 5.6 72 0 0.1 ΰ) 170 5.8

*) Below the 30 ppm limit. in which hydrocarbons could be reliably determined with the test device.
**) The CO values were all between 0.05 and 0.15%.

Since the speeds at which the car when equipped with the carburetor 50 type B according to the F i g. 6 to 8 were not the same as the investigations with the carburetor 30 type A after F i g. 3 to 5, the results cannot be compared directly. However, it can be stated that in general the exhaust emissions for an engine in connection with the carburetor 50 type B were even lower than with the type A carburettor.

As a further test of a carburetor 50 type B, this was compared with a rambler, that with a the usual carburetor. The test was carried out at a speed of 56 km / h. The dynamometer was set so that about 20 HP road load on the rear wheels of the car to simulate a run under load. The results of this test are in Table HI also shows the significant reductions in exhaust emissions

I 14

Table 111

1936 Rambler at 56 km / h and 20 hp on the road

Hydrocarbon ppm

CO%

NO ₁ ppm

O2%

Normally 120 0.49

0 ·) 0.15

Mixture device
Type B

3360 4.0 650 6.2, o

") Below the 30 ppm limit for hydrocarbons could be reliably determined with the test device.

<5

The reason that the inventive Carburetor has such significant reductions in undesirable exhaust emissions, results in primarily from two interrelated factors, namely the type and uniformity of the mixture of entrained fuel produced by the carburetor and intake air once is through a fine distribution, a thorough mixing and an im essential complete entrainment of the liquid fuel through the intake air with each work cycle a substantially uniform fuel-air mixture is supplied to the individual cylinders. the The type and uniformity of this fuel-air mixture reduce the differences to a considerable extent cylinder to cylinder and cycle to cycle producing misfire and one incomplete combustion can result with the usual gasification systems. As a result, this is it The fuel-air mixture used is much leaner than the one previously used. It's generally known, that theoretically complete combustion will occur at a stoichiometric air-fuel ratio should, namely at 15.5: 1. It is evident that in practice this theoretical ideal condition does not exist in the cylinders of known engines and that as a result the carburettors were previously set so that fuel-air mixtures were supplied, which were richer than the stoichiometric ratio. With such rich fuel-air ratios complete combustion does not occur and there is a significant release of unburned hydrocarbons and carbon monoxide. Because the combustion with these fats Mixtures is not complete and so in the cylinders excess fuel is present, the final combustion temperature will be lower than if fuel and air can be burned in a stoichiometric ratio. This in turn causes the generation of nitrogen oxides, as their formation is promoted by high combustion temperatures.

In order to reduce the generation of unburned hydrocarbons and carbon monoxide, the carburettor have been set in the last time so as to result in fuel-air mixtures which f as close to ₀ as possible to the stoichiometric ratio. While this was effective in reducing hydrocarbon and carbon monoxide emissions because of the more complete combustion of the fuel-air mixture, it also increased the production of nitrogen oxides as a result of the higher combustion temperature. In fact, it has been found that the generation of nitrogen oxides is highest at stoichiometric ratios or in a somewhat leaner state than at stoichiometric ratios

An important result of the invention is that due to the significantly improved uniformity the fuel-air mixtures, as they are generated by the carburetor according to the invention, dei The engine can now run with air-fuel mixtures which are considerably leaner than the stoichiometric ratio without the misfiring that usually occurs when intermittent the leanness limits of an air-fuel ratio exceeded from cylinder to cylinder or from work cycle to work cycle. Indeed it was found that an engine so equipped with air-fuel ratios of the order of magnitude runs well from 20: 1 to 30: 1, i.e. with air-fuel mixtures, which are much leaner than possible with complete evaporation of the air-fuel mixture was held.

A fuel to air ratio of 20: 1 works out roughly 30% more oxygen for combustion than the stoichiometric ratio requires. Therefore, when complete combustion of the fuel takes place, the exhaust gases contain about 5% free oxygen. It was found that using this free oxygen in a significant way the reduction of the maximum combustion temperature and the formation of nitrogen oxides. It should be pointed out here that with an exhaust gas control system as it is in use today, free Air is introduced into the exhaust manifold. However, the present invention differs from this arrangement in a very important way. This is where the excess oxygen comes together with the fuel introduced as a result of using a fuel to air ratio in the The order of magnitude of 20: 1 or greater, so that the oxygen during the entire combustion process is present and available.

With regard to a second important factor of the invention, namely the type of fuel-air mixture, it is believed that this has an equal, if not greater, role in the depreciation of unwanted exhaust emissions from engines that use the novel device.

By having the fuel in contact with the high velocity intake air that flows through the narrowing of the carburetor, the liquid fuel becomes fine dispersed droplets are broken and then the intake air is loaded with them. This together with the thorough mixing of fuel and air results in a substantially uniform air-fuel mixture to all cylinders with every single work cycle without the need to put the fuel in the essential to completely vaporize before entering these cylinders. This in turn leads to significant improvements over the now known fuel-air induction systems that use a require high levels of fuel vaporization to achieve useful results.

Because in the context of the present invention, the fuel does not evaporate outside the cylinder must be, the air-fuel mixture, as it is supplied to the cylinders, both cooler and cooler has not absorbed the heat necessary for evaporation, and for this reason is more dense, and is

Finally, it is also denser because the finely divided liquid fuel takes up less volume than a vaporized fuel. It is evident that a denser fuel-air mixture is more powerful than a less density generated. This increases the performance of the engine through this factor.

The temperature of the fuel-air mixture at the end of compression is a consequence of the invention also lower than with conventional engines, which heat up the intake air to evaporate the Need fuel. The lower final compression temperature according to the invention is partly related the lower temperature of the fuel-air mixture together as it was at the beginning - as above mentioned - is sucked into the cylinder. The final compression temperature is further reduced by that part of the compression heat for evaporation of the fuel inside the cylinder is used. In addition, since the final compression temperature is lower, so is the combustion temperature also lower according to the invention compared to the other systems. As already mentioned, there are fewer nitrogen oxides at lower combustion temperatures educated.

The lower compression temperature also appears to have an impact on the octane requirement of the fuel to have with a particular engine. When the compression temperature is lower than the air-fuel charge for an engine with a given compression ratio, it is less likely to that this charge ignites itself. This allows the same fuel for engines with higher compressions can be used, or it can be for an engine with a specific compression ratio a fuel with a lower octane number can be used. The latter process allows a fuel cost saving because a lower octane fuel is normally used is sold at a price below that of good high octane fuel.

It is further believed that the type of air-fuel charge according to the invention also related to a lowering of the octane requirement for the fuel used Apparently : This is due to a faster rate of combustion reaction of the air-fuel charge according to the invention compared to the ratios common carburetor systems. For example, a Buick V8 was found to be vintage 1963, with a displacement of 3.5 liters and a compression ratio of 11: 1, the present invention won the award Results both in terms of performance and in terms of lower exhaust emissions unleaded regular gasoline of approximately 84 to 86 octane number and also higher quality, lead-containing gasoline Regular gasoline with an octane rating of approximately 91 to 93 yields. On the other hand, if the engine is equipped with a standard four-channel carburetor, it requires a high-quality leaded gasoline with an octane rating of approximately 98 to 100.

The results of the tests on the high-compression Buick V8 engine, vintage 1963, when comparing a conventional carburetor with the Type B mixture system are set out in Table IV. Again, the same testing equipment and procedures were used as for the Rambler engine.

Table IV Fuel Coals CO% NO, O2% l.ufl- consumption hydrogen ppm BrennsKiff- I / 100 km ppm Discount Neutral high-quality 310 3, b0 60 1.3 Normal ver gas normal 120 0.15 11th 4.6 Mixed leadless 30th 0.15 0 4.7 direction Type B 56 km / h high-quality 350 0.40 1200 2.2 12.5 / 1 10.9 Normal ver gas normal 0 0.15 15th 6.8 24.2 / 1 9.2 Mixed leadless 15th 0.15 35 5.4 23.6 / 1 12.4 direction Type B 72 km / h high-quality 300 1.20 1450 1.6 12.5 / 1 13.1 Normal ver gas normal 0 0.15 135 8.5 25.2 / 1 11.0 Mixed leadless 0 0.15 180 5.0 23.2 / 1 11.0 direction Type B

Again from Table IV it can be seen that there is a substantial reduction in exhaust emissions can be achieved using the invention. The tests at 56 and 72 km / h show that Carburetor according to the invention allows the engine to run at considerably higher fuel-air ratios and permitted with slightly lower fuel consumption.

After finding these results, the

60 and driven at 64 km / h with normal road traffic, and the fuel-air ratio was further reduced. These results are set out in Table V and confirm the improvement in engine efficiency, the engine's ability to run on unleaded gasoline, and the reduction in engine efficiency
Exhaust emissions.

709 607/197

Table V fuel Coals
hydrogen
ppm CO% NO.
ppm Oi % Air-
Fuel-
ratio consumption
1/100 km normal
leadless 15th
0 0.07
0.05 70
2b0 IU
12.1 27.8 / 1
31.2 / 1 7.2
6.3 Mixed
direction
Type B

In all of the aforementioned tests, the fuel was injected into the carburetor through the nozzle 40 at approximately 2.7 kg / cm ^{2 of} air pressure to disperse the fuel from the nozzle. It was found, however, that it is not essential that the

Table Vl

Fuel is sprayed into the device. According to In Table VI, the Buick engine was also tested with approximately 20 horsepower applied to the rear wheels attacked to investigate the efficiency.

fuel

Hydrocarbon ppm

CO %

NO <

ppm

Leisiunj »
PS

Standard carburetor type B high-quality 180 1.1 2200 2.0 24 With air of 2.7 kg / cm ² normal 0 0.15 1020 7.0 23 Without additional air normal 15th 0.15 270 b.O 23

In fact, under these power ratios, the type B carburetor reduced without air pressure at the nozzle the generation of nitrogen oxides compared to the arrangement in which the nozzle operated with compressed air.

This fact leads to the construction of the carburetor 60 as shown in FIG. F i g. 9 to 13 is shown. As shown in FIG. 11, this embodiment is similar to the previously described embodiments 20 and 30, a converging constriction 62 and a throttle member 63. between which one Ring opening 65 is formed. In Fig. 11, the throttle member 63 is in its uppermost position in the Constriction 62, and the outlet oil opening 65 has its largest cross-sectional area.

The throttle member 63 has a lower converging end piece 64 with an angle of convergence which is smaller than the convergence angle of the throat is 62. As already explained above, these form two parts an atomizer to capture a significant portion of the kinetic energy of a high speed having air to convert into static energy, so that the air speed of sound air over a can accept a large area of the manifold vacuum. The constriction 62 also has a diverging, lower duct piece 66 to further increase the length of the atomizer. The similarity of this arrangement with the schematic representation according to FIG. 2B is obvious.

Liquid fuel is fed to the carburetor 60 via a line 68 which is connected to a sleeve 69 in which the constriction 62 is located. The sleeve 69 has an annular groove 70 with. the line 68 communicates so as to distribute the fuel on the outside of the throat 62. Above the annular groove 70, the sleeve 69 has an inner diameter such that a free annular space 71 is formed between the sleeve 69 and the constriction 62. The fuel flows from the annular groove 70 upwards through the annular space 71 and via an annular lip 72 to the upper end of the constriction 62.

When the throttle member 63 is in its uppermost position, the one flowing in via the annular lip 72 becomes Fuel directly exposed to the flow of high velocity intake air which flows through the narrow outlet opening 65. The high-speed intake air is cracked the liquid fuel from the ring lip and takes it with it in finely divided form. The speed of the Intake air is then considerably reduced when this air enters through the atomizer of the carburetor 60 flows into the intake manifold in such a way that a substantial and usable part of the finely divided fuel is carried along by the intake air as it continues to flow to the engine cylinders.

In order to change and regulate the size of the constriction of the annular Ausittsöffnur.g 65, can the throttle member 63 can be moved axially in the constriction 62. As can be seen from Figures 9 to 11, this is Throttle member 63 centered in throat 62 by arms 75 connected to the top of sleeve 69 The throttle member also carries a ball nut 76 in the manner of a ball head bearing into which the threaded end a rod 77 is screwed. Rotation of the throttle member 63 is prevented by a pin 78 which extends downward from an arm 75 into an opening in the upper part of the throttle member. If the Rod 77 is rotated, so the throttle member 63 is depending on the direction of rotation of the ball nut 76 Rod moved up or down, whereby the cross-sectional area of the outlet opening 65 can be changed.

In the illustrated embodiment, the rotation of the rod 77 is through a rack and pinion an actuating device having a pinion effects which is designated as a whole by 80. As shown in Fig As can be seen, a reciprocating control member 81 is provided with a rack 82 at one end (see in particular Fig. 12). The rack 82 kämmi

f> o with a pinion 83 which is fastened on a shaft 84 which is mounted in bearings of the body 85 of the actuating device 80. This wave carries another Gear 85 which comes with a gear 86 arranged on a shaft 87 (see Figs. 9 and 12) Another wheel 88 on the shaft 87 meshes with a gear 89 on a shaft 90, the lower end of which Chain wheel 91 carries (see Fig. 12). The lower end of the Rod 77 also carries a sprocket 92. with the

Sprocket 91 is coupled by a chain 93 (see Fig. 13). When the rod 81 according to FIG. 9 is moved to the right, the damper 63 is shown in FIG. 11 moves downward and vice versa, the maximum upper and lower Siellungen of the throttle member are adjustable fixed by a stop pin 95 or 96 of the rod 77 which is opposite adjusting screws 97 and 98 of the frame 99 strikers can.

The control of the gasifier 60 the supplied fuel is related to the throat '° of the constriction 62 of the throttle member 63. For this purpose, fed by an unillustrated pump fuel under pressure to a control valve 100 which is connected to the line 68 leading to the Sleeve 69 leads. The control valve 100 has a metering opening 101 and a conical valve needle 102 which regulate the flow of the fuel through the outlet opening. The valve needle is arranged in a gland packing 103 of the regulating valve 100 such that it can be moved back and forth.

The interaction of the control valve 100 with the throttle element 63 is achieved via a bracket 105 which connects the rod 81 to the valve needle 102 . The tab 105 is connected at a central part by a pin to a block 106 into which the threaded end 107 of the needle is screwed. At one end the tab 105 is provided with a slot 108 which is engaged by a pin 109 of the rod 81 and at the other end the tab has a slot 110 for receiving an adjustment device in the form of a pivot pin 111 which is attached to a block 112 , which is mounted so that it can move back and forth in a guide channel 113 arranged on the frame 99. When the rod 81 is displaced to the right as shown in FIG. 9, the tab 105 rotates about the step 111 and moves the valve needle 102 to the right, so that the passage through the metering opening 101 is reduced.

In order to adjust the fuel flow for a certain position of the throttle element, the threaded end 107 of the valve needle can in or out of the block 106

Table VI

This can be screwed out in order to reduce or increase the fuel nut through the outlet opening 101. The change in fuel flow in connection with changes in the position of the throttle member can also be effected by changing the position of the pivot pin 111 about which the tab 105 is pivoted. This is accomplished by turning a screw 115 carried by a slide 112 and screwed into an end plate 116 of the frame 99. By changing the pivot point of the tab 105 , the amount of movement of the valve needle 102 relative to the rod 81 is changed.

In order to compensate for the vacuum in the intake manifold, through which the throttle member 63 is drawn down into the mouth part 62 , the mixture device 60 is equipped with parts with servo action. For this purpose, a vacuum opening 120 is arranged in the base plate 121 of the mixing device, and a vacuum line 122 connects this vacuum opening 120 to a cylinder 123, the piston 124 of which carries a rack 125 which interacts with the gear 85. When the vacuum at the vacuum opening 120 increases, the piston 124 moves the rack 125 in such a direction that the throttle member 63 is raised and the vacuum is thereby reduced. This arrangement now requires a much smaller force to be exerted on the rod 81; to be in order to adjust the position of the throttle member 63

The carburetor 60 according to FIGS. 9 to 13 was fitted to a 1970 Ford Torino engine. This engine had a displacement of 5.8 liters and a compression ratio of 10.7: 1. It also had a four-channel carburettor as standard equipment, and it was recommended that use a good quality fuel.

With this Ford engine, the same test facility and the same procedure as above and the results are summarized in Table VII.

fuel

Hydrocarbon ppm CO%

NOv ppm O>

Neutral
Normal carburetor
Mixture device
TypeC

72 km / h

Normal carburetor

Mixture device

TypeC

high-quality

normal

leadless

high-quality

normal

leadless

300 48 15

170

30th

4.25 25th 0 0.68 - *) 6.0 0.50 - *) 4.6 0.45 2600 0.7 0.25 480 6.5 220 7.0

*) no reading taken.

The results in Table VII again clearly show that there is a considerable reduction in exhaust emissions has been achieved using the invention. At the same time, the octa requirement was in bezu; significantly reduced on the engine and thus the fuel economy improved.

For this purpose 4 sheets of drawings

Claims (1)

Patent claims: 1. Carburetor for internal combustion engines with an air intake line in which an arbitrarily variable cross-section , e.g. B. annular constriction is arranged which the fuel can be supplied in corresponding quantities. and which is followed by an atomizer part with a gradually increasing cross-section , characterized by the combination of the following features, a) that the formation of the atomizing (28a, b) and its associated constriction isi made such that over a substantial part of the speed and load range by rights conservation of the critical Druckve <holds isses at the constriction speed of sound is present, b) that a fuel feed device (40, 41) is provided, the delivery rate of which is in Dependence on the change in cross-section of the throat (28a. 2. Carburetor according to claim 1, characterized in that that the increase in the cross-sectional area of the atomizer part forms a cone with an opening angle from about 6 to 8 °. 5. Carburetor according to claim 1 or 2, characterized in that the fuel supply device is arranged as a fuel nozzle (40) upstream of the constriction (28a, b) in such a way that the fuel on the inner wall of the narrowing part (32) of the air intake line (31) flows to the bottleneck. 4. Carburetor according to claim 1 or 2, with a throttle member associated with the constriction, which with the help an actuating device is axially movable. characterized in that the actuating device for controlling the fuel supply is coupled to the fuel supply device. 5. Carburetor according to claim 4, characterized in that on the actuating device through a vacuum line (120) from an intake manifold (21) a force acting counter to a force exerted by a vacuum in the Luftansaugleitiing (31) on the throttle member (63) can be exerted. 6. Carburetor according to claim 4 or 5, characterized in that the actuating device for controlling the fuel supply comprises an adjusting device (111, 115) for adjusting the increase in the _{fuel supplied in this way} with an increase in the air flow causing movement of the throttle member (63). 7. Carburetor according to the preceding claims 1 to 6, characterized in that the Narrow point in the air intake line (31) is independent of the position of the throttle element.