DE2104301A1 - System or device for reducing the impurities contained in exhaust gases - Google Patents

Description

DA-4077

Description of the company's patent application

SUN OIL COMPANY 1608 Walnut Street Philadelphia, PA 19103, USA

concerning

System or device for reducing the impurities contained in exhaust gases

Priority: January 29, 1970 U.S.A. No. 6832

The invention relates to the control of the exhausts of motor vehicles fed by gasoline Internal combustion engines with internal combustion

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are driven, released substances, in particular such a control of these released substances that certain Air pollutants (e.g. mist-forming "impurities that are commonly found in the exhaust gases of automobiles.

This application is in a general context ^ with the German patent application, P 20 64 290.4 from December 29, 1970.

It was found that certain types of atmosphere Pollutants commonly found in automobile exhaust gases should be reduced; In fact are standard values at federal level with regard to the maximum limit for the release of carbon dioxide and carbon monoxide from exhausts has been set on the basis of mass ions. Further be currently standard values for the emissions of nitrogen oxides (which are referred to below by KO) in detail to advise. Furthermore, it is also desirable to reduce exhaust emissions of aldehydes.

An object of the present invention is to provide a new emissions control system for To create motor vehicles.

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Another object is to provide an emissions control and control system for automobiles that will Driveability and controllability or operability of the automobile is not adversely affected.

Another object of the invention is considered an emission control to create and control system for motor vehicles, which results shows that ^w is a significant improvement over factory-fitted car show mobile.

Briefly, the objects on which this invention is based are achieved in the following way: In the internal combustion engine with internal combustion of a motor vehicle, the fully vaporizing (full-boiling) gasoline as fuel is used, the carburetor is mechanically modified in such a way that ei * under idling operating conditions an enrichment of the fuel-air mixture ^ j hexvorrufs that is fed to the engine. Furthermore, an arrangement or device used which can selectively or selectively set the carburetor to "lean" (i.e. the fuel-air mixture that is fed to the engine at a higher engine or vehicle speed can become emaciated or leaner). At the exhaust of the internal combustion engine are at high

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Temperature working (heat) exhaust reactors are used. The enrichment suppresses the formation of NO and also reduces the emission or release of aldehydes, while the emaciation minimizes the drop in fuel economy and the additional consumption. The downstream arranged heat reactors remove flammable gases from the exhaust or the exhaust gases by combustion, like hydrocarbons and carbon monoxide.

The invention is explained in more detail in the following detailed description in conjunction with the drawings.

It shows:

Fig. 1 is a schematic representation of the essential elements of an emissions control and control system for a motor vehicle (system for reducing impurities in exhaust gases) according to the present invention;

Fig. 2 is a schematic representation of a

optional or selecting carburetor control or control device, the can be used according to the invention.

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First of all, -Pig. 1 referred to. An internal combustion engine is indicated quite schematically by the reference number 1 with internal combustion of the V-type (cylinders in V-arrangement) that uses fully evaporating gasoline as fuel (a so-called fossil fuel or a hydrocarbon fuel). A carburetor 2 of somewhat conventional construction, but in modified ftj in the manner described below (to have an enrichment effect plus an optional or to achieve a selective leaning effect), the two rows of cylinders of the engine 1 have a fuel-air mixture to. The optional leaning effect or activity of the gasifier 2 is determined by means of a control and control device 3, which will be described below.

In the engine room (engine compartment) of the motor vehicle _A-finished (for example, an automobile), a V / ärmeieaktor 4 is mounted, which receives the exhaust gases (exhaust) of a cylinder bank, and a second reactor V, which is also installed in the engine room and the exhaust gases from the other bank of cylinders. The respective outlet connections 5 and 6 of the reactors 4 and V are connected to the conventional exhaust system of the automobile, which has a silencer or several silencers, exhaust gas

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21Q43Ü1

having pipes, etc.

Reference is now made to FIG. 2, which shows a part of the carburetor 2 together in a somewhat schematic manner with additions including the control and control device 3 shows. According to the present invention, a Reduction in RO emissions (perhaps more precisely a reduction in the formation of NO in the combustion chambers of the Machine) by enriching the air-fuel mixture, which is generated during idling operating conditions (or, to put it another way, during urban, light accelerations that are part of a driving cycle), is fed to the suction opening of the machine. In this context it was found that the majority urban NO emissions occur during these light or partial gas accelerations.

In Pig. In Fig. 2, part of one of the main pipes of a 4-pipe carburetor is shown at 7, in which a throttle valve 8 of conventional design is pivotably mounted. The wide open or full throttle position of the throttle valve 8 is shown with solid lines, while the position of the throttle valve close to idle is shown with dash-dot experts Lines is shown. In the last-mentioned position, the main pipe or the main bore 7 is very little

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or slightly open. The lower end of the main pipe 7 leads to the intake pipe of the machine, while 8 Venturi passages or nozzles (not shown) that introduce gasoline from the carburetor tank or the carburetor housing into the bore 7, so that this is mixed with air and (as soon as the throttle valve 8 is sufficiently open) into the intake pipe of the machine is fed in. At a small distance below the position of the throttle indicated by dash-dotted lines Flap 8 guides a needle hole 22 for the idle mixture, in which an adjustable needle valve which can be actuated by an idle adjustment screw (not shown) is arranged is, in the main bore 7i such that an air-fuel mixture (via the hole 22) into the bore 7 below the throttle valve (and therefore into the inlet valve of the machine-) can be fed in when the throttle valve is in its fully closed or "Idle" position. This fully closed or "idle position" of the throttle valve 8 is one those in which the throttle valve closes the bore 7 somewhat more completely than it does in the dash-dotted line shown "near idle" position does.

A pair of idle outlet openings 9 and 9 ', which are vertically spaced from one another, lead slightly above

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of the needle hole 22 for the idle mixture in the main bore 7, so that a fuel-air mixture means
these openings below the throttle valve 8 in the
Hole 7 (and thus in the inlet valve of the machine)
can be fed in when the throttle valve is in its dot-dash "idle position". In some carburetors, only a single idle outlet slot can be provided instead of two separate idle outlet openings 9 and 9 '. The fuel
for this air-fuel mixture (as well as the fuel for the fuel-air mixture produced by the
Hole 22 is supplied) is originally derived from the float housing of the carburetor and flows from the main tank of the carburetor via the idle pipe 23, the
has a limitation (not shown) to which
Holes 9 and 9 ¹ , being along its way
mixes with air. All related to the carburetor
elements mentioned, such as the float housing, the main tank, the main bore, the throttle valve, the idle pipe etc /. are as integral parts of it in that
Carburetor body included.

'In an embodiment of the invention that was actually built for experimental purposes and successfully tested
the originally factory carburetor was replaced

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Increase in the idle pipe restriction or restrictions (there may be more than one of these restrictions in the carburetor) by means of suitable Processing modified. (On an economic basis or in the case of mass production, the original or original, factory-made carburettors themselves are of course redesigned to accommodate these enlargements to effect, so that no special processing would be necessary). The increase in the idle pipe restriction or narrowing (i.e., increasing its diameter) allows an enriched idle with a leaner setting of the idle adjustment screw, which, on the other hand, is considerably enriched conditions causes during idling operation. This enrichment des during near-idle conditions (as a result of adapting or "trimming" the narrowing of the Idle pipe) fed to the intake pipe of the machine Air-fuel mixture brings about light accelerations (Partial throttle), as they recur while driving, with a reduction in NO emissions themselves. Additional enrichment beyond (above) idle speeds can be achieved through enrichment of the main metering nozzles (i.e. by reducing the diameter of the primary metering needle). The latter can, but need not be necessary

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and depends on the size of the machine, the use of the vehicle etc. from.

After an enrichment of the air-fuel mixture supplied to the intake pipe in the manner described above and would seek to affect all operating conditions of the machine (i.e., in all positions of the throttle valve 8, the idle position perhaps excepted), there would necessarily be an overall loss of economic viability result in fuel consumption. About the economy of fuel consumption at higher driving speeds (Motorway speeds) where tailpipe emissions are a minor issue the carburetor 2 is controlled or controlled in such a way that it has an optional leaning effect available which results in a depletion of the air-fuel mixture supplied to the intake valve, namely at all Jvehicle speeds above a selected one, previously set speed, e.g. approximately 58 km per hour (35 mph). This emaciation or. Impoverishment is caused by the optional or selective Carburetor control and control device 3 as a function of the engine speed or engine speed evoked. It may be pointed out

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that the Abmagerungswirkung is generated by air holes of the throttle bore from the speed dependent (temperature-controlled) are.

Above the main throttle valve 8 there are one or more air holes leading into the main bore 7 of the carburetor or air supplies 10 are provided. From the feed or a line (pipe or hose) 11 extends from the inlets 10 to a source of purified air at atmospheric pressure, for example to the outflow side of the gasifier erluftS.lt ers. In line-11 there is a solenoid valve and a calibrated restriction 13 of the air supply is provided (the latter as an alternative an adjustable Needle valve) when valve 12 is open air purified by the vacuum of the suction pipe through the air line 11 and the restriction 13 into the main bore of the carburetor retracted (assuming that the throttle valve 8 is sufficiently open), this additional Air flow increases the air-fuel ratio of the mixture that flows to the intake pipe, thus causing this mixture to become depleted.

Current surges are derived from the ignition coil of the machine, the pole speed of which is of course the speed of the Machine is directly proportional, and at 14 in the input

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a current impulse counting and triggering unit 15 fed, which rectifies these current impulses and an internal The trigger circuit that is set in such a way that that it generates a signal voltage on the output lines 16 of the unit 15 when the following speed der.input current surges of a predetermined engine speed corresponds, for example, to that speed which is approximately a vehicle speed of 58 km / h (35 mph) equals.

The unit 15 may comprise a commercially available tachometer-type plague circuit, such as is often shown in FIG Races used as indicators for overspeeding of machines will. These units are dependent on the machine speed and generate an output signal voltage, as soon as a certain machine speed is reached. The output lines 16 are one with the coil Relay 17 connected which has a pair of normally closed contacts 18 which, when closed, Feed 12 volts of voltage (coming from the vehicle battery) to an electromagnet 19 that controls the valve 12 in the air line 11 actuated for the supply of air to the carburetor bore. The arrangement is such that if the Electromagnet 19 is de-energized, valve 12 is open

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and the bore 7 supplies air. It is pointed out at this point that the elements 14-18 essentially the control and control device $ of FIG. 1 form.

At or above the preselected machine speed or engine speed, which is approximately a vehicle speed, for example of 58 km / h, the latter being regarded as the "trigger" or release speed can, the sequence frequency of the ignition current surges fed into the unit 15 is large enough to trigger the trigger circuit this unit to operate, whereby a signal voltage on the lines 16 is generated. Through this the relay 17 is energized for the purpose of opening its contacts 18, which in turn the electromagnet 19 is de-energized and the valve 12 opens to supply air to the main bore 7 of the carburetor. These are those shown in FIG Conditions. By opening the valve 12, cleaned air is passed through the air line 11 into the bore 7 sucked, thereby increasing the air-fuel ratio and the air-fuel mixture supplied to the engine intake becomes emaciated or impoverished. As described above, this optionally seeks abmage- " tion or depletion of the mixture afterwards, at higher speeds the economy of gasoline consumption restore.

Below the "trigger speed" is on the lines 16 no signal voltage available, relay 17 is de-energized, the contacts 18 are closed and the electromagnet 19, which closes the valve 12, is energized and closes the supply of additional air to the carburetor bore 7 from. Therefore, under these conditions there is no emaciation of the air-fuel flowing to the intake of the internal combustion engine -Mixture.

It may be more appropriate to use an alternative to the special air openings 10 in the bore 7. For example a ventilation plate like a thick seal can be used as a holder for the carburetor, which is an array of transverse passages on v / e, extending from the outside of the ventilation plate to the carburetor bore extend towards. The outer ends or openings of these passages would then be purified to a source or filtered air can be connected by means of a valve (like the one with the reference symbol 12) and a calibrated air restriction 13

It will be on Pig again. 1 referred to. As already mentioned above, the emissions control and control system according to the present invention, a pair of heat reactors 4 and 4 'for the combustion of the coal

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monoxyds and the hydrocarbons (as well as other fuels such as aldehydes) that appear in the exhaust gases or in the exhaust from the combustion chambers or cylinders of the internal combustion engine. One heat reactor 4- is connected to the four exhaust ports of a cylinder row of the V-type internal combustion engine 1, while exactly the same heat reactor 4 is connected to the four exhaust ports of the other cylinder row of the engine. The heat reactors 4 and 4 ¹ are not described here in great detail since they do not form part of the present invention on their own; for example, they can be of the type disclosed in U.S. Patent 3,413,803. The structure of this reactor has two tubes in a concentric arrangement and has no catalyst; the outer tube has a relatively thin layer of heat insulating material on its inner surfaces. Each reactor has four inlet connections, each of which is intended for one of the four cylinders of the corresponding cylinder bank, and a single outlet connection; These reactors can therefore be referred to as tailpipe Y / poor reactors. With regard to reactor A-

_is_ one of the inlet connections_s_ch ^ matic at_ 20_and

the outlet connection also shown schematically at 5; the latter connection extends to the muffler etc. of the dual exhaust system of the automobile.

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10983? / 1? 20

In the reactor 4 'an inlet connection is shown schematically with 21 and denotes the outlet connection with 6; the latter connection also extends to the muffler etc. of the dual exhaust system of the automobile.

Although it has not been shown in the drawing, an air injection system (second air supply system) is preferably ^{used in connection with the heat reactors 4 and 4 1.} This system uses an air delivery pump belt driven by the machine and has a filter and muffler at its inlet. From this pump, air is continuously supplied by means of individual supply pipes and ducts to a point located just below each exhaust valve, i.e. outside of each combustion chamber or cylinder, so that the air is supplied or at each exhaust valve, but just below the combustion chambers or cylinders . is sent on the way to reactors 4 and 4 '.

As described in the cited patent, oxidation (i.e. Combustion) instead of hydrocarbons and carbon monoxide in the exhaust gases (exhaust from the combustion chambers the machine) are included, with the oxidation reaction

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is exacerbated by various types of turbulence created in the reactors. In addition to that in the Combustion of carbon monoxide and reactors taking place Hydrocarbons are required that also combustion or oxidation of aldehydes takes place, which are in the exhaust gases May be left over from the combustion chambers of the machine, as these aldehydes are flammable substances.

It may be noted at this point that the enrichment described in connection with FIG. 2, as well as the Arrangement for the optional leaning of the mixture on the supply system -respectively. work at the inlet of the machine, while the heat reactors work at the outlet or exhaust of the machine. However, there is an important interaction or interplay between the two, as will now be explained. The complete overall system includes two combustion devices, which must work harmoniously with one another (namely firstly the internal combustion engine itself and secondly the heat reactors). First of all, the carburetor is optimized (through enrichment) to the NO compounds to reduce to a minimum (at the same time also the aldehydes, which decrease with richer mixtures), at the same time good machine operation, economy and drivability are maintained. Furthermore, the second must Air supply system (i.e. the air that is actually in

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the heat reactors is blown in) be dimensioned so that it gives the reactors a suitable air-fuel ratio, such that the latter a) burn the carbon monoxide and the hydrocarbons completely and b) at the same time that the poor do not react be burned yourself.

For example, in order to minimize the level of KO and aldehydes in the combustion chamber (via enrichment in the carburetor), 6 % carbon monoxide could be produced (which is largely due to the effect of enrichment, in which more fuel gets into the cylinders). This means that more carbon monoxide is sent to the heat reactors as fuel; without additional air, the reactors would not burn this carbon monoxide properly, either because of unsuitable or incomplete chemical equilibrium or because of unsuitable or insufficient combustion temperatures. The ratio of CO to the air supplied to the reactors is critical because an optimal combustion temperature is desired for reducing emissions; at the same time, the combustion must be limited in such a way that the temperatures do not become so high that the reactors themselves burn. Therefore, the in the inlet of the reactors (by means of the second air supply system) must

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air volume adjusted or set (readjusted) v / ground in such a way that the effect caused in the carburetor for the purpose of producing a certain amount of carbon monoxide is compensated; At the same time, the amount of carbon monoxide produced by enrichment (and therefore the amount of enrichment) must be carefully balanced, 'as already described above, the gasifier enrichment used in the present invention (under conditions close to idling) requires the supply of additional air to the reactors (by means of of the second air supply system described), beyond that which would be supplied to the reactors in the absence of any enrichment in order to oxidize or burn properly the carbon monoxide and the hydrocarbons in the exhaust gases of the combustion chamber. This means that, when the enrichment is actually cut off by closing the part of the optional, Abnagerungseinrichtung, an excess of air is present, JL · of the reactors 4 and M 'protects against overheating, that is at higher speeds, the reactors more air supplied than you need; they continue to act to reduce the hydrocarbons, carbon monoxide and aldehydes to a low level, but the excess air prevents the reactor temperature from increasing further and thus counteracts any tendency for the reactors to burn out.

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Because of the enrichment used in the emission monitoring and control device according to the present invention, the internal combustion engine requires a little more gasoline; that is, in the present system there is a reduction in fuel economy. At 4-8 km / h (30 mph) a loss of about 13 ⁰ P in fuel savings (km per liter) was determined, even if the reduction in fuel savings is relatively small when driving on the motorway (96 km / h or 60 mph) ( which is primarily due to the sometimes leaning of the air-fuel mixture at higher speeds, which is a characteristic of the carburetor control according to FIG. 2). However, even this reduction or loss (about 13%) in fuel economy is small compared to the losses encountered with other emissions control systems.

It is usually used in conjunction with thermal or catalytic reactors uses an additional ignition delay to get a quick V / Arm and additional reactor temperature, whereby a reduced emission level or content of impurities should be achieved (compared to the one obtained without additional delay). However, this additional ignition delay brings a strong one Waste in gasoline savings or the gasoline economy

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and a deterioration in vehicle performance or drivability, as well as an increase in temperatures under the hood. It should be noted that that preferably no additional ignition delay is used in the present system. To this In this way, the disadvantages of an additional ignition delay are avoided.

In the past, exhaust gas recirculation was often used to reduce the emission of NO. this However, it definitely and significantly adversely affects the operation or the performance and drivability of the Car out. There is also the control (ventilating or controlling, diverting or switching) of hot exhaust gases extremely difficult irnd easily leads to adversity. In the system of the present invention, preferably there is none Exhaust gas recirculation used; this again raises the problems associated with such recirculation avoided.

As described above, the optional leaning device for the carburetor of FIG. 2 is of in-engine speed dependent, since the current impulses for the ignition at 14 are fed into the "unit 15". It can under certain It may be more desirable to use the carburetor control or control rather than relying on the hashine

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-.22- 21 ΠΑ

based on the vehicle speed, for example in the case of a vehicle with an automatic power transmission, at v / elcher
Slippage occurs and in which some of the fuel economy may otherwise be lost as a result of this slippage. When using the vehicle speed
A small pulse generator could be used in the power transmission or in the transmission shaft (shaft extension) which operates the speedometer in order to generate current impulses (proportional to the vehicle speed) which are fed into the input of the unit 15. Alternatively, one could also be used to monitor or control the leaning device for the carburetor
mechanical (not using current surges) sensing or scanning of the vehicle speed. For this purpose it is foreseen that switches of a known type (which depend on the transmission pressure or on the speed of the drive) can be used for a suitable control of the electromagnet 19.

The following example showing the new emissions control
and control system for a motor vehicle according to the present invention and the results achieved therewith
is given without any intention of limiting the invention to this example. The Frobeent

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ORIGINAL iNSFE

took and the analysis of the emission components were in the prescribed procedure in accordance with the statutory test procedure (Federal test procedure) carried out under Using the seven-way cycle. In the absence of regulations or statutory provisions, the NO content was determined by taking a sample according to H.E.W. (H.E.W, recommended sampling) and determined by the subsequent Saltzman determination or determined. The motor vehicle used was a 19G> 7 Chevrolet Camaro, a sporty, performance-oriented one Vehicle with a 350 cubic inch engine (5i736 Liters) and manual transmission. A one of his .Rochester 4MV-A.I.R .-% uadra, jet "carburettors were used in this vehicle, the enlarged or widened constrictions or restrictions of the idle pipe according to the invention had, as well as slightly enlarged main orifices, and also in accordance with the in Fig. 2 The principles explained was modified in order to provide air openings in the throttle bore that are speed-controlled (or speed controlled) were. Included were used for exhaust heaters of the type mentioned in the above The type described in the patent is used.

The following table I shows the data obtained with this vehicle in a hot cycle test (hot cycle test data).

109837/12? 0

ΝΟ _χ , ppm
CO, %
HC, ppm

Table I. Modified Modified against Factory Motor vehicle above the factory equipped moderately equipped th motor vehicle 147 12th üllion
1203 0.21 21st "1.0 45 21st 217

Gasoline consumption, (in km / 1) (30 mph) 48 km / h 9.4 (50 mph) 80.5 km / h 7.9 (60 mph) 96.5 km / h 6.7

8.1 7.0

6.4

87 89 96

As noted, Table I shows only the data from a hot cycle test. The following Table II shows the data obtained on a composite cold start seven-way cycle. In the latter table it is interesting to note that during the first cycle, when the choke is operated, the NQ level is extremely low, which would indicate a dependence on additional accumulation, even if one compares the low levels achieved during the entire test ; unfortunately the low NO _x content is due to the increase in carbon dioxide and

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Hydrocarbons balanced during the first cycle,

Table II

Cycle CO, % HC, ppm NO. ppm

1 0.93 100 78 2 0.40 76 163 3 0.26 78 165 0.27 80 157 5 6th 0.27 70 141 7th 0.19 60 184

Total 0.31 71 155

set

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Claims (16)

Claims 1.) Device for reducing the in the exhaust one with fossil fuel-powered internal combustion engine for a motor vehicle Contaminants, characterized by a device for leaning the inlet of the Internal combustion engine (1) supplied fuel-air mixture at speeds of the machine or the Vehicles at or above a preselected speed and by a device which acts on the exhaust gases flowing out of the combustion chambers of the machine by at least a part of carbon monoxide and hydrocarbons contained in These exhaust gases are contained to be converted into harmless substances. 2. Device according to claim 1, characterized in that the former means so as to increase acts imaging speeds of the air to fuel ratio of the mixture at Haschinen- or driving the at or be above the preselected speed. - 27- 109837/1220 3. Apparatus according to claim 1, characterized in that the first-mentioned device depends on the machine or vehicle speed "or is controlled by this. • 4. Device according to Claim 1, characterized in that the machine has a carburetor
for the supply of a fuel-air mixture
to the suction opening, on which the first-mentioned device acts. 5. Device according to claim 4, characterized in that g e k e η η that the former depends on the speed of the machine or the vehicle depends. 6. The device according to claim 4, characterized in that the first-mentioned device has a connected to the carburetor, actuatable element for the supply of air to the suction opening of the machine and the speed of the machine
or the vehicle dependent means for actuation
of the air supply element. 7. The device according to claim 1, characterized in that g e k e η η - 109837/1220 - 28 - - GO - draws that the last-mentioned device has a Wärruereaktor which in operation at least burns some of the carbon monoxide and hydrocarbons contained in the exhaust gases. 8. Apparatus according to claim 1, characterized in that the latter device a heat reactor with inlet connections and an outlet connection, connections between the combustion chambers of the engine and the inlet connections and a connection between the exhaust pipe and the outlet connection having. 9 · Arrangement for checking or controlling exhaust emissions an internal combustion engine using fossil fuel for a motor vehicle, characterized by a carburetor for the supply of air-fuel mixture to the intake port of the engine and through one at speeds of the machine or vehicle at or above a preselected speed optionally or selectively acting on the carburetor device to increase the air-fuel ratio in the mixture. - 29-109837 / 1220 10. The arrangement according to claim 9 »characterized in that the device on the speed depends on the machine or vehicle. 11. The arrangement according to claim 9, characterized in that the device is one with the Has carburetor connected, actuatable element for the supply of air to the suction opening of the machine as well as means for actuation which are dependent on the speed of the machine or of the vehicle of the air supply element. 12. A method of controlling tailpipe emissions from a fossil fuel using Internal combustion engine with internal combustion for a motor vehicle, marked thereby net that the intake of the machine supplied Fuel-air mixture under idling and those operating conditions in which there is a low throughput during the main measurement, is enriched, that the composition of the mixture at speeds of the machine or the motor vehicle or is optionally varied above a preselected speed, and that the in the exhaust of the - ^ O 109837/1220 - 3o - Machine to burn existing flammable gases. 13. The method according to claim 12, characterized in that the varying v / ahlweise or selectively depending on the speed of the machine or the motor vehicle is effected. 14. The method according to claim 12, characterized in that the varying the leaning of the air-fuel mixture includes. 15 · Process for controlling tailpipe emissions from a fossil fuel using Internal combustion engine for a motor vehicle, characterized by g e k e η η that the fuel-air pressure supplied to the intake opening of the machine is below Operating conditions close to idle and those in which low throughput occurs during main measurement, is enriched, and that the composition of the mixture is optionally or selectively varied. 16. The method according to claim 15 »characterized in that the varying is optional or selectively depending on the speed - 31 109837/1220 the machine or the motor vehicle will. 17 · The method according to claim 15 *, characterized in that the varying the leaning of the fuel-air mixture includes. 109837/1220 Blank page