DE4231575C2 - Method and device for controlling an internal combustion engine - Google Patents

Description

The invention relates to a method and a device for control an internal combustion engine, in particular an effec tive reduction of harmful components of the in the Initial start phase of the internal combustion engine emitted Allow exhaust gas.

The exhaust gas from an internal combustion engine contains harmful Components such as B. carbon monoxide (CO), hydrocarbons  (HC) and nitrogen oxides (NOx). These harmful be components have a disadvantage as air pollutants influence the human body and impede it the plant growth.

To the amount of these harmful Be contained in the exhaust gas To reduce components, investigations were carried out on Reini supply of the internal combustion engine exhaust gas by an Exhaust system provided catalytic exhaust converter carried out with a three-way catalyst.

Although the amount of harmful components in the exhaust can be reduced by a catalyst in the exhaust system can, the cleaning ability unfolds only after the catalyst was raised to a temperature at which he becomes active. Until the catalyst on an activation temperature is heated, the exhaust gas cleaning ability of the catalyst very low, so that the hardly degraded harmful components are released into the atmosphere.

The temperature at which the catalytic converter becomes active depends on the composition of the catalyst and is usually 250 to 400 ° C, as in the JP 54-16018 A is described.

A period of approximately 2 minutes or longer is required from the start of an internal combustion engine, so that the catalyst gas is heated to 250 to 400 ° C. In some publications, e.g. B. is JP 54-79319 A. the time required for this is 3 to 5 minutes give.  

For a system to reduce harmful inventory parts in the internal combustion engine exhaust with one in the exhaust system arranged cleaning catalyst is therefore essential meaning, like for a few minutes after firing engine start until the catalyst heats up an active temperature emitted pollutant components in the Exhaust gas can be reduced effectively.

EP 0 422 432 A1 describes a method for exhaust gas after-treatment act disclosed on an internal combustion engine, in which an afterburner for combustion contained in the exhaust gas Hydrocarbons a catalytic converter (in particular a 3-way catalytic converter), the exhaust gas rich mixture from the internal combustion engine and additionally receives the fresh air required for combustion. The Fresh air flow is from the intake tract of the internal combustion engine ne branched off downstream of an air mass meter. The ver remaining intake air flow becomes fuel in one supplied in such a quantity that for the air masses knife determined a stoichiometric intake air flow or superstoichiometric mixture. The combustion power machine is at least in the heating phase of the catalytic converter Tor operated with a richer mixture because of the intake air stream a partial stream in the form of be for the afterburner agreed fresh air flow is branched off after the Size of the intake air flow was determined.

DE 41 06 249 A1 describes a catalytic device cleaning of the exhaust gases of an internal combustion engine wrote in the first in a combustion chamber group associated exhaust pipe a heater and a he ster catalyst are arranged. In a second one another combustion chamber group is assigned an exhaust pipe second catalyst arranged. Using suitable valves and bypass lines can be the path of the exhaust gas through the Arrangement of the catalysts are influenced, so that the both catalysts operated either in series or in parallel  become. The temperatures of the catalyst assembly now conditions (partly on the input side, partly on the output side) detected by sensors and temperature-dependent switching gears triggered in such a way that with a cold start first the three devices are connected in series at the exhaust gases preheated by the heater in the first Catalyst due to its oxidizing mode of operation of an excess of air are burned further and thus accelerated heating of the second catalyst follows. The combustion, i.e. H. Oxidation, is caused by a Secondary air supply in front of the catalysts supported.

The object of the invention is a device and a method for controlling an internal combustion engine to create at which the temperature of an exhaust gas purification catalyst in the exhaust system of the internal combustion engine telbar after the start of the internal combustion engine on a Ka Talysator activation temperature can be raised.

The invention provides a device for controlling a Internal combustion engines with a fuel injector and an air flow control valve in an air intake system and an exhaust gas purifier arranged in an exhaust gas system tion catalyst. The device has means in the the temperature of the exhaust gas arranged in the exhaust system Cleaning catalyst to control the fuel spray valve and the air flow control valve in the air suction system is entered to make the mixture fatter to ma than through the stoichiometric air-fuel Ratio determined when the inlet temperature is lower as a predetermined value.

The specified temperature value of the exhaust gas cleaning catalyst sator is a temperature at which the catalyst is active becomes. When the temperature of the exhaust gas purification catalyst  in the engine exhaust system is less than the activation temperature of the catalyst, the Amount of fuel supplied increases or the amount of the intake air is reduced to make the mixture richer than through the stoichiometric air-fuel Ratio determined so the constituents in the exhaust gas change that the catalyst temperature raised quickly can be.

The components in the exhaust gas of the internal combustion engine specifically changed with the air-fuel ratio. If the engine was operating under one condition in which the mixture is fatter than by the stoichiometric air-fuel ratio determined become a lot of carbon monoxide and a lot of hydrocarbon fabrics produced. It should be noted that up to 10% Carbon monoxide and more is contained in the exhaust gas, which is significant is higher than the concentration of hydrocarbons.

If the internal combustion engine with an air-fuel A / F ratio of 14.7 (where A and F are air and Denote fuel mass) is operated Amount of carbon monoxide less than 1%.

Carbon monoxide is released at a significantly lower temperature burned as hydrocarbon. If the internal combustion machine intake system accordingly a mixture is supplied, which is fatter than the stoichiometric air Determined fuel ratio, carbon monoxide can a catalyst will be burned even if the tempe exhaust gas temperature is low. The temperature of the Kataly sators can be generated by this combustion  Heat to be raised.

If the engine was operating under one condition in which the mixture is fatter than by the stoichiometric air-fuel ratio determined significantly more hydrocarbon would be produced. The amount of heat generated per unit mass of coal Hydrogen is 5 times higher than that of carbon monoxide.

If the mixture is made richer than the stoichio metric air-fuel ratio is determined additional catalytic combustion of the hydrocarbon for catalytic combustion of carbon monoxide leads so that the temperature of the catalyst quickly can be raised.

As a result, harmful components in the exhaust gas even in the initial phase of starting the engine effective by quickly increasing the catalyst temperature can be eliminated.

Furthermore is a front Direction for controlling an internal combustion engine with a Fuel injection valve and an air quantity adjustment valve in one air intake system and one in one Exhaust system arranged catalytic exhaust gas cleaning system provided. The device contains means to which is the temperature of the arranged in the exhaust system Exhaust gas purification catalyst to compare the input temperature with a predetermined temperature value will give means for generating a signal to a Mixture to make it fatter than the stoichiometric one  Air-fuel ratio determines when the temperature of the exhaust gas purification catalyst is less than that before given temperature value, and control means for opening or Closing the fuel injector and air quantity adjustment valve in the air intake system depending from the signal mentioned.

Furthermore is a front Direction for controlling an internal combustion engine with a Fuel injection valve and an air quantity adjustment valve in one air intake system and one in one Exhaust system arranged exhaust gas purification catalyst intended. The device contains means for input the temperature of a catalyst in the exhaust system arranged exhaust gas purification catalyst, means for Spei a specified temperature value of the exhaust gas purification tion catalyst, means for comparing the catalyst temperature in the exhaust gas purification catalyst from the input average with the specified temperature value from the memory average, means for generating a signal, for connection lubrication of a mixture compared to that by the stoichio metric air-fuel ratio certain value, when the temperature of the exhaust gas purification catalyst is lower than the predetermined temperature value, and control means to open or close the fuel injector and the air volume adjustment valve in the air intake system depending on the signal mentioned.

If the temperature of the exhaust gas purification catalyst ge is ringer than a given value, it is advantageous the fuel injector and the air volume adjustment valve til open or close in the air intake system so  that the air-fuel ratio A / F (A and F denote air and fuel masses) not less than 10 and not higher than 13.

When the temperature of the exhaust gas arranged in the exhaust system cleaning catalyst is higher than the specified value, it is advantageous to the fuel injector and the air quantity adjustment valve in the air intake system open or close that air-fuel ratio equal to the stoichiometric air-fuel ratio is or approximately corresponds to this. Both of the above Controls mentioned can be by using a Microcomputers are carried out.

The invention can be used in an internal combustion engine, which are a fuel injector and an amount of air Control valve in the air intake system, and a Combustion catalyst and a three-way catalyst in the exhaust system. In this case it is advantageous the combustion catalytic converter before the three-way catalytic converter to arrange. By greasing the mixture over that through the stoichiometric air-fuel ratio the combustion catalytic converter works at a certain value effective so that the temperature of the exhaust gas cleaning catalyst through that of the combustion catalyst generated heat can be raised quickly.

The invention is also in an internal combustion engine reversible which is a fuel injector and an air quantity control valve in the air intake system, and a combustion catalyst and an exhaust gas purification catalyst in the exhaust system and air supply devices  at the precursor of the combustion catalyst. Since the Oxygen concentration in the exhaust gas is low when the Internal combustion engine is operated under a condition in which the mixture is richer than the air-fuel Mixture determined, the oxygen may not be sufficient, if carbon monoxide and hydrocarbon are in the exhaust the catalyst is burned. The problem of not sufficient oxygen is solved in that the Exhaust system air is supplied when the internal combustion engine is operated under a condition in which the mixture is richer than the stoichiometric air-fuel Ratio determined. Such control of the air can also by the control device of the invention be performed.

A system for exhaust gas purification with an internal combustion engine control according to the invention will now be in the following wrote.

Such a system for purifying the exhaust gas Internal combustion engine has an air intake system Fuel injection valve and an air quantity adjustment valve, e.g. B. a throttle, and a pre-form tested catalyst with a combustion catalyst and an exhaust gas purification main catalyst in an exhaust gas system and has means for detecting the temperature of the Main emission control catalyst and means (control unit) to open or close the fuel spray valve and the air volume adjustment valve, see above that in a period from the start of the internal combustion engine until the exhaust gas purification main catalytic converter reaches a temperature is heated at which the catalyst becomes active,  the mixture is richer than the stoichiometric one Air-fuel ratio determined.

It is advantageous to the fuel injector and to open or close the air flow adjustment valve that the mixture for a period from the start of the burning engine to the main exhaust gas purification catalyst is heated to a temperature at which the catalyst becomes fatter than the stoichiometric Air-fuel ratio and that the air Fuel ratio equal to the stoichiometric air Fuel ratio is made or approximated, when the temperature of the main exhaust gas purification catalyst reaches a temperature at which the catalyst is active becomes.

It is possible that the air-fuel ratio A / F (where A and F are air and fuel masses, respectively not) when operating with a rich mixture is less than 10 and not higher than 13. It's ins special possible, a richer mix among such a condition that the CO concentration of the Exhaust gas is not less than 3 and not more than 14.

It is advantageous to use the main exhaust gas purification catalyst z. B. under the vehicle floor and the upstream Catalyst with a combustion catalyst if possible to be arranged close to the internal combustion engine. The temperature of the exhaust gas is flowing through the exhaust pipe reduced. If the upstream catalyst if possible is arranged close to the internal combustion engine, that can Exhaust gases are fed to the catalysts while the  Exhaust gas temperature is not reduced. This can the oxidation ability of CO and HC can be increased.

It is advantageous to have means for feeding an oxi dationsmittel, z. B. air, upstream in the exhaust pipe to provide the upstream catalyst.

The oxygen concentration in the exhaust gas is at Burning in the fat area is generally low. By supplying an oxygen-containing gas, z. B. air, at the preliminary stage of the upstream kata lysators, can burn CO and HC in the upstream catalyst performed effectively become.

It is possible that the amount of air supplied (Oxygen) equivalent to stoichiometric oxygen Exhaust gas consumption or only slightly higher is. In this case, both the combustion in the upstream catalyst, as well as in the exhaust gas cleaning Main catalyst performed in an excellent way become.

It is possible that the upstream catalyst is a combustion catalyst that has an activity in has the oxidation of CO and HC. It is in particular possible as a catalyst activation component at least one metal or metal oxide from group VIII and Ib of the period table, rare earth metals, zinc and use tin.

It is advantageous as a main exhaust gas purification catalyst  to use a three way catalyst that has an oxi dation activation of CO and HC and a reduction acti crossing of NOx.

It is possible that a ceramic honeycomb structure made of cordierite, mullite, aluminum titanate, etc. as a carrier is used for the upstream catalyst the above-mentioned catalyst activation components to wear. Alternatively, it is advantageous that a ceramic honeycomb that is a carrier with a porous carrier, such as. B. silicon dioxide, Alumina, titanium dioxide is coated to it to incorporate the catalyst activation components.

In the exhaust gas purification system according to the invention it essential by the combustion with the pre switched catalyst generated heat to heat the upstream catalyst itself for activation to use. This can be achieved by lowering it the thermal conductivity of the catalyst support substance and of the carrier and by increasing the temperature gradient between the catalyst and the carrier or Carrier. The ceramics mentioned above are minor Thermal conductivity so that the temperature of the cat tors can be lifted quickly. A honeycomb-like body per from an electrically conductive metal or Alloy, such as B. stainless steel, can be used as a carrier can be used for the upstream catalyst.

A quick heating of the catalyst can also be there can be achieved by that the specific heat of the Carrier substance or the carrier of the catalyst less  is made. The honeycomb metal body, like z. B. stainless steel, is used as a carrier for the catalytic converter tor used so that the specific heat of the material is lowered and making a thin plate of this Material is made possible. As a result, the Heat capacity can be made lower and so faster temperature rise is made possible.

It is also possible to use the upstream catalyst by heating an electric current through is led through it.

The temperature increase can take place more quickly, that an electrical current through the carrier material or the support of the catalyst is passed to the Kataly heat by Joule heat. A temperature This can increase the upstream catalyst done faster that an electrical current through the Catalyst at the beginning of the temperature rise of the kata lysators is directed to promote the combustion of CO countries.

The invention further provides a method for operating a Internal combustion engine in front of which the internal combustion engine by supplying fuel and air in the stoichiometric Air-fuel ratio is driven and an exhaust gas is cleaned with an exhaust gas purification catalyst. The Internal combustion engine is operated under a condition in which the mixture for a period from the start of the burning Engine to at least the exhaust gas purification catalyst is heated to an activation temperature, is richer than the stoichiometric air-fuel ratio  certainly.

It is also a system for purifying an exhaust gas Internal combustion engine provided in which the internal combustion engine machine is started under a condition in which the Mixture is fatter than through the stoichiometric air Determines fuel ratio, and the exhaust gas with a Combustion catalytic converter and then burned is supplied to an exhaust gas purification catalyst. If the temperature of the exhaust gas purification catalyst to a Temperature is raised at which the catalyst is active the supply of the fat mixture is stopped and the exhaust gas is passed through the combustion catalytic converter tors fed directly to the exhaust gas purification catalyst.

A vehicle according to the invention comprises an exhaust gas cleaner tion catalyst in an exhaust pipe of an internal combustion engine machine and means by which the internal combustion engine for a certain period of time from the start of internal combustion machine until the exhaust gas purification catalytic converter A mixture is supplied heated to the activation temperature that is fatter than the stoichiometric air Fuel ratio determined. In the exhaust pipe upstream of the exhaust gas purification catalyst Combustion catalyst for catalytic combustion of the exhaust gas arranged, which of the with the rich Mixture-operated internal combustion engine is emitted.

The invention is preferably applied to a vehicle Petrol or diesel engine used.

A system for cleaning the exhaust gas of an internal combustion engine  according to the invention comprises a bypass line for a Exhaust pipe leading from the internal combustion engine to the exhaust gas Cleaning main catalyst leads, the bypass line tion consisting of a combustion catalyst may contain upstream catalyst.

The upstream catalyst is essentially over liquid after a short period of time (about 2 minu ten) was in use immediately after the start. If that Exhaust gas is passed through the upstream catalyst even after this has become superfluous, the Pressure loss increased. If the upstream Kataly exposed to high temperatures for a long time this causes damage to the catalyst. In that from the internal combustion engine to the main catalytic converter leading exhaust duct, a bypass is provided in which the upstream catalyst is arranged. A ver Burning with a rich mixture is only for a period of time carried out in which the main catalyst is not yet one Working temperature immediately after the start of the firing engine has reached. The exhaust gas is through the upstream catalyst in the bypass in the main kata initiator initiated. This allows the above Problems to be solved.

Advantageously, in the exhaust duct between the internal combustion engine and the upstream catalytic converter a dehumidifier, preferably a cooling Dehumidifier. If the temperature of the pre switched catalyst is not higher than the dew point of the exhaust gas, it is advantageous to use the exhaust gas with the ent dehumidifying device. For example  by cooling the exhaust gas to a temperature, which are equal to or less than the temperature of the pre switched catalyst, and then by supplying the dehumidified exhaust gas to the upstream catalyst respectively.

The exhaust gas from an internal combustion engine usually contains a large amount of water vapor. If that's the water steam containing exhaust gas at a low temperature having upstream catalyst is supplied, more precisely a temperature that is not higher than that Dew point of the exhaust gas, the contained in the exhaust gas condenses Water on the catalyst or in the pores of the Kataly crystallizer. This phenomenon cannot just work of the catalyst, but also reduce the catalyst damage and will increase pressure loss. As soon as the Condensation occurs, is a heat of conversion for ver vaporization of the condensate required. So it's a lot Heat required to increase the temperature of the condensate to lift and this takes a long time. The con water vapor condensation on the upstream catalyzer sator can be prevented by dehumidifying the exhaust gas. This can occur, for example, by cooling the exhaust gas a temperature equal to or lower than that Temperature of the upstream catalyst and then by Supply of the cooled, dehumidified exhaust gas to the front switched catalyst. With the emission control system in which a bypass in one of the internal combustion engine arranged to the main catalyst leading exhaust duct and a combustion catalyst is provided in the bypass, it is advantageous if the bypass line has an exhaust gas has dehumidifier. If the temperature  of the upstream catalyst no higher than the dew point of the burned exhaust gas, the exhaust gas is through the dehumidifier in the bypass dehumidifies and then fed to the main catalyst. If the temperature of the upstream catalyst not lower than that Is the dew point of the exhaust gas, the exhaust gas is directly in front of it switched catalyst supplied.

If the temperature of the upstream catalyst is not is lower than the dew point of the exhaust gas Possibility of water condensation. dehumidification of the exhaust gas is not required under this condition. Therefore, in that from the internal combustion engine to the main kata bypass duct provided and A device for dehumidification is in the bypass line of the exhaust gas included. If the temperature of the previous catalyst not higher than the dew point of the is burned exhaust gas, the exhaust gas is removed by the ent humidification device in the bypass dehumidified and then the Main catalyst supplied. If the temperature of the upstream catalyst not lower than that Is the dew point of the exhaust gas, the exhaust gas is directly the Main catalyst supplied. In this way, the Condensation of the water in the upstream catalyst and the related problems without initiating one unnecessary drainage can be prevented.

The feeding of a mixture that is fatter than through determines the stoichiometric air-fuel mixture, is disclosed in JP-61-58912 A. However, it is not Countermeasure for that in the initial launch phase of Internal combustion engine emitted exhaust gas is taken into account.

Further advantages and special features of the invention result from the following description of execution play with the drawing. Show it:

Figure 1 is a schematic view of a system for cleaning the exhaust gas of an internal combustion engine.

Fig. 2 is a graph showing the typical relationship between the air-fuel ratio and the exhaust gas composition in a gasoline engine;

Fig. 3 is a schematic view of an implementation of a system for cleaning the exhaust gas from an internal combustion engine;

Fig. 4 is a schematic view of another system for purification of exhaust gas of an internal combustion engine; and

FIG. 5 is a block diagram showing the detailed structure of a control unit according to FIG. 1.

As shown in Fig. 1, an upstream catalyst 2 and a main catalyst 3 is arranged in the exhaust duct 11 of an internal combustion engine 1 . An air quantity adjustment valve (throttle valve) 8 and a fuel injection valve 9 are seen in the inlet channel 4 of the internal combustion engine 1 . The opening of the air quantity adjustment valve 8 and the fuel injection valve 9 is controlled by a control unit (control box) 10 . A secondary air supply line 6 is provided at the preliminary stage of the upstream catalytic converter 2 of the exhaust gas duct 11 . The secondary air supply line 6 has an air pump 5 . A temperature sensor 7 for detecting the temperature of the main catalytic converter and / or the exhaust gas is provided on the output stage of the main catalytic converter 3 . The detected temperature is inputted to the control unit 10, where the control unit 10 determined by comparing the detected temperature with a pre given value, whether an operation is continued with a rich mixture or not.

The detailed structure of the control unit 10 shown in FIG. 1 is shown in FIG. 5. A signal of the temperature sensor 7 in the main catalyst 3 is converted by an input circuit into a form suitable for comparison with the predetermined value of the catalyst temperature and then fed to a comparator of a comparator unit, in which it is compared with the predetermined catalyst temperature which was previously stored in a storage unit was saved. When the temperature of the main catalyst 3 is lower than the predetermined value, a signal generator or a signal generating unit generates a signal that adjusts the fuel injection valve 9 and the throttle valve 8 to make the mixture richer than the stoichiometric air-fuel ratio determines and generates a signal that turns on the air pump 5 . These signals are converted in the output circuit into the shapes suitable for the respective starting objects and are fed to the fuel injection valve 9 , the throttle valve 8 and the air pump 5 .

When the temperature of the main catalyst 3 is higher than the predetermined value, the signal generating device generates a signal that adjusts the fuel injection valve 9 and the throttle valve 8 to make the air-fuel ratio equal to or approximately the stoichiometric ratio, and one Signal that switches off the air pump. The signals are converted in the output circuits into forms suitable for the respective output objects and are fed to the fuel injection valve 9 , the throttle valve 8 and the air pump.

Fig. 2 shows the relationship between the air-fuel ratio and the exhaust gas composition in a gasoline engine.

FIG. 3 shows a schematic view of an embodiment of a system for cleaning the exhaust gas of an internal combustion engine according to the invention. A bypass line 20 is provided in an exhaust gas duct of the internal combustion engine. A bypass catalytic converter 2 is located in the bypass line. Valves 12 and 21 are provided to change the flow of the exhaust gas. The temperature of the main catalyst and / or the exhaust gas at the outlet of the main catalyst 3 is detected by a temperature sensor 7 . The signal from the sensor 7 , which denotes the temperature of the main catalytic converter and / or the exhaust gas, is input to a control unit 10 . If the temperature he takes equal to or lower than the activation temperature of the main catalyst 3 , the valve 21 is closed and the valve 12 is opened so that the exhaust gas is introduced into the upstream catalyst 2 of the bypass line 20 . Simultaneously with this, an air quantity adjusting valve 8 and a fuel injection valve 9 are controlled so that combustion is carried out with a rich mixture. If the temperature of the exhaust gas is not lower than the temperature of the main catalyst 3 , the valves 21 and 12 are opened and closed accordingly to introduce the exhaust gas directly into the main catalyst 3 . Simultaneously with this, a valve 8 for adjusting the intake air quantity and a fuel injection valve 9 are controlled so that combustion is carried out under a condition of a stoichiometric air-fuel ratio and approximately to it. Signals for opening and closing the valves 12 and 21 are also output by the control unit 10 .

Fig. 4 shows a schematic view of another system for purification of exhaust gas of an internal combustion engine. A bypass line 20 is connected to an exhaust gas duct 11 of the internal combustion engine, and a dehumidifying device 15 is provided in the bypass line 20 . Valves 13 and 14 for diverting the exhaust gas flow are arranged in the channel 11 and the bypass line 20 , respectively. A temperature sensor 16 is contained in the upstream catalytic converter 2 . If the temperature of the upstream catalytic converter 2 is lower than the dew point of the exhaust gas, the exhaust gas is introduced into the main catalytic converter 3 after it has been dehumidified by the dehumidifying device 15 of the bypass channel 20 . If the temperature of the upstream catalyst 2 is higher than the dew point of the exhaust gas, the exhaust gas is fed directly to the upstream catalyst 2 . The opening and closing of the valves 13 and 14 is also carried out by the control unit 10 . By comparing the temperature measured by the temperature sensor 16 with the dew point of the exhaust gas, which was previously stored, the control unit 10 can output signals for opening or closing the valves 13 and 14, for example.

example 1

The upstream catalyst 2 contains 0.5% by mass of Pd, which is carried by a ceramic (cordierite) honeycomb carrier which has a volume of 1 liter, an opening ratio of 76% and is coated with aluminum oxide. The main catalyst 2 comprises a honeycomb-shaped carrier which has a volume of 2 liters, has the same structure as the upstream catalyst 2 and has Pd, Pt and Rh. Exhaust gas from a gasoline engine was passed through the upstream catalyst and the main catalyst 2 and 3 , which were connected in series. The exhaust gas, which contains 7 volume percent CO and 0.35 volume percent HC, is achieved by burning a mixture at an air-fuel ratio of 12 where the mixture is richer than that of the stoichiometric air-fuel ratio is, the upstream catalyst 2 was fed at a flow rate of 1000 liters per minute. 63 seconds after the exhaust gas was introduced, an exhaust gas temperature of 300 ° C. was reached at the outlet of the upstream catalytic converter. 135 seconds after the introduction of the exhaust gas, an exhaust gas temperature of 300 ° C. was reached at the outlet of the main catalyst 7 .

Comparative Example 1

The exhaust gas containing 0.9 volume% CO and 0.2 volume% HC, which was achieved by combustion of the mixture at an air-fuel ratio of 14.5, which is close to the stoichiometric air-fuel ratio , The upstream catalyst 2 was fed at a flow rate of 1000 liters / minute. At the outputs of the upstream and the main catalyst 2 and 3 , an exhaust gas temperature of 300 ° C was reached 89 and 170 seconds after the introduction of the exhaust gas.

Example 2

The upstream and the main catalyst were the same as those used in Example 1. The exhaust gas, that with the same combustion condition (air-fuel Ratio of 12) was generated before the pre switched catalyst air added at 380 liters / minute. At the outputs of the upstream and main catalytic converters became an exhaust gas temperature of 300 ° C 40 and 87 respectively Reached seconds after the exhaust gas was introduced.

Example 3

The amount of time it took for the temperature of the exhaust gas at the outlet of the upstream catalyst 300 ° C was measured when used under different catalysts under the same conditions as in Example 2. The ge in Table 1 showed results achieved. Ceramic honeycomb carrier were used as a carrier for the upstream and Main catalyst. The supports were made of aluminum oxide layers to the active kata shown in Table 1 wear lytic components.  

Table 1

Example 4

Upstream catalysts with different porous Carriers and carriers bearing Pd and Pt were used under the same condition as in Example 2.  

The results of Table 2 were obtained by measuring the Time that was needed for the temperature to reach of the exhaust gas at the outlet of the upstream catalyst 300 ° C reached.  

Example 5

There was an upstream catalyst with a honeycomb like structure that has a porosity of 50% featured a sheet of ferritic stainless Steel with a thickness of 0.05 mm and 0.5 mass% Pd wore. The rate of temperature increase of the Catalyst was measured under the same condition as in example 2. At the outputs of the upstream and the main catalyst became the exhaust gas temperatures of 300 ° C after 36 and 83 seconds.

Example 6

The same catalyst as in Example 5 was used. A direct current power of 3 kW was given by the Kata lysator conducted under the same condition as in Bei game 3. At the outputs of the upstream and the The main catalyst was the exhaust gas temperature of 300 ° C reached after 28 and 62 seconds, respectively.

According to the invention, unburned or only partially burned fuel components are cleaned, the emitted immediately after the start of an internal combustion engine become. In particular, it is an upstream catalyst intended. The internal combustion engine is under a rich Condition started so that the temperature of the previous quickly catalyzed by the oxidation of the exhaust gas is raised. The temperature of the main catalyst arranged downstream of the upstream catalyst can be raised to an operating temperature. This directly increases the exhaust gas cleaning ability after the start of the internal combustion engine.

Claims (9)

1. Method for controlling an internal combustion engine with a fuel injection valve ( 9 ) and an air quantity adjusting valve ( 8 ) and an exhaust gas purification catalytic converter ( 3 ) arranged in an exhaust system, in which the following steps are carried out:

• A) detecting a temperature of the exhaust gas cleaning catalyst ( 3 ) and / or the exhaust gases at the outlet of the exhaust gas cleaning catalyst ( 3 ),
• B) comparing the detected temperature with an activation temperature of the exhaust gas purification catalyst ( 3 ),
• C) triggering the fuel injection valve ( 9 ) and / or the air quantity adjusting valve ( 8 ) so that the air / fuel mixture supplied to the internal combustion engine becomes richer than a stoichiometric mixture if the detected temperature is below the activation temperature of the exhaust gas purification catalyst ( 3 ),
• D) actuating the fuel injection valve ( 9 ) and / or the air quantity adjusting valve ( 8 ) so that the air / fuel mixture is adjusted to the stoichiometric mixture or approximately when the exhaust gas purification catalyst ( 3 ) has reached the activation temperature,
• E) passing the exhaust gases through a the Abgasreinigungska talysator (3) upstream of the combustion catalyst (2) which oxidizes carbon monoxide and hydrocarbons contained in the exhaust gas, the combustion catalyst is provided in a bypass line (20) (2) of the below the activation temperature From gas cleaning catalyst ( 3 ) switched on and off above the same, and
• F) supplying an oxidizing agent upstream of the catalysts ( 2 , 3 ) when the detected temperature is below the activation temperature of the exhaust gas purification catalyst ( 3 ).

2. The method according to claim 1, characterized in that the oxidizing agent contains secondary air which is supplied via a secondary air supply line ( 6 ). 3. The method according to claim 1 or 2, characterized in that the exhaust gas purification catalyst ( 3 ) is a 3-way catalyst. 4. The method according to any one of claims 1 to 3, characterized in that a dehumidifying device ( 15 ) is connected upstream of the combustion catalyst ( 2 ), which dehumidifies the exhaust gas and is switched on at a temperature of the upstream catalyst ( 2 ) below the dew point of the exhaust gas and is switched off at a temperature of the upstream catalyst ( 2 ) above the same. 5. Device for controlling an internal combustion engine having a fuel injection valve (9) and a Luftmen geneinstellventil (8), one being in an exhaust system arranged exhaust gas purifying catalyst (3), an exhaust gas purification catalyst (3) upstream, arranged in a bypass line (20), combustion catalyst ( 2 ), which oxidizes the carbon monoxides and hydrocarbons contained in the exhaust gas, and a control unit ( 10 ) which

• A) detects) a temperature of the exhaust gas purifying catalyst (3) and / or of the exhaust gases at the output of Abgasreinigungska talysators (3,
• B) compares the detected temperature with an activation temperature of the exhaust gas purification catalyst ( 3 ),
• C) controls the fuel injection valve ( 9 ) and / or the air quantity adjustment valve ( 8 ) so that the air / fuel mixture supplied to the internal combustion engine is set richer than a stoichiometric mixture if the detected temperature is below the activation temperature of the exhaust gas purification catalyst ( 3 ) lies,
• D) controls the fuel injection valve ( 9 ) and / or the air quantity adjustment valve ( 8 ) such that the air / fuel mixture is adjusted to the stoichiometric mixture or approximately when the exhaust gas purification catalyst ( 3 ) has reached the activation temperature,
• E) the bypass line ( 20 ) below the activation temperature of the exhaust gas purification catalyst ( 3 ) is switched on and off above it, and
• F) a supply of an oxidizing agent upstream of the catalysts ( 2 , 3 ) when the temperature detected is below the activation temperature of the exhaust gas cleaning catalyst ( 3 ).

6. The device according to claim 5, characterized in that the oxidizing agent contains secondary air which can be fed via a secondary air supply line ( 6 ). 7. The device according to claim 5 or 6, characterized in that the exhaust gas purification catalyst ( 3 ) is a 3-way catalyst. 8. Device according to one of claims 5 to 7, characterized in that a dehumidifying device ( 15 ) is upstream of the Ver combustion catalyst ( 2 ), which moistens the exhaust gas ent and at a temperature of the upstream catalyst ( 2 ) below the dew point of Exhaust gas can be switched on and switched off at a temperature of the upstream catalyst ( 2 ) above the same. 9. Vehicle having a device according to one of claims 5 contains up to 8.