EP1753951A1

EP1753951A1 - Control system for a mobile internal combustion engine

Info

Publication number: EP1753951A1
Application number: EP05755958A
Authority: EP
Inventors: Rolf BRÜCK
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Vitesco Technologies Lohmar Verwaltungs GmbH
Priority date: 2004-06-09
Filing date: 2005-06-03
Publication date: 2007-02-21
Also published as: WO2005121533A1; DE102004027907A1; JP2008501887A; CN1993542A; US20070089402A1; JP5049126B2; US7874144B2; KR20070015243A; RU2007100135A; RU2395697C2

Abstract

The invention relates to a method for controlling a fuel mixture by means of a control probe (1) in the waste-gas system (2) of a mobile internal combustion engine (3). The waste-gas system (2) comprises at least one catalytic converter (4) which is disposed in a waste-gas line (5), and control thereof is carried out by means of an individual control probe (1) disposed in the inside of at least one catalytic converter (4). The invention also relates to a waste-gas system (2) which is suitable therefor.

Description

Control system for a mobile internal combustion engine

The invention relates to a method for regulating a fuel mixture with a control probe in the exhaust system of a mobile internal combustion engine. Furthermore, an exhaust system comprising a mobile internal combustion engine is proposed. The preferred area of application for such exhaust systems and processes is in the automotive sector.

It is known to use sensors and / or probes in exhaust systems of mobile internal combustion engines in order to obtain detailed information about the operating states of the internal combustion engines or of exhaust gas treatment devices which are integrated in the exhaust system.

For example, it is known to determine the aging condition of an exhaust gas catalytic converter with the aid of an oxygen sensor connected to an electronic control unit. The sensor has an oxygen-sensitive area for measuring the oxygen partial pressure in the exhaust gas. The control unit uses this measurement variable to determine the aging condition of the catalytic converter, since the oxygen loading of the catalytic converter can be used as a parameter for its functionality (so-called onboard diagnosis).

Furthermore, it is also known to monitor at least one component of the exhaust gas in the exhaust system and thus to influence the fuel supply to the internal combustion engine. For example, oxygen sensors are used to control the lambda engine when the internal combustion engine has warmed up or after a predefined exhaust gas temperature has been reached. The so-called air ratio "lambda" (λ) describes the ratio of the current air-fuel ratio to the stoichiometric air-fuel ratio and is often used as a characteristic parameter for the combustion processes. Here, a first, upstream of a catalytic converter is used. ter oxygen sensor as a control probe and a second oxygen sensor downstream of the exhaust gas catalytic converter as a trim probe. With the aid of the first oxygen sensor, a lambda oscillation with a specific amplitude and frequency is determined, which result from the combustion processes in the internal combustion engine. This is detected by means of the first oxygen sensor positioned in front of the catalytic converter. The procedure is familiar to the person skilled in the art and requires no further discussion here.

The lambda vibration of the exhaust gas composition on the inlet side of the catalytic converter is increasingly smoothed out as it passes through the catalytic converter due to its oxygen storage capacity. The result is a decrease in the amplitude of the lambda vibrations along the catalytic converter. If the oxygen storage capacity is high, for example, almost no lambda vibration can be detected on the output side of the catalytic converter. The amplitude of the still detectable lambda oscillation after the exhaust gas has passed through a partial section or the entire catalytic converter is therefore a measure of the oxygen storage capacity of the catalytic converter section or the entire catalytic converter.

In this case, the lambda value generally settles to the constant mean value of the lambda oscillation in front of the catalytic converter. This mean value is recorded by the second sensor downstream of the catalytic converter, the so-called trim probe. The trim probe is now used to set an average value of lambda which cannot be exactly determined or set on the basis of the oxygen or control sensor upstream (the catalytic converter). Reasons for this are, for example, a so-called "poisoning", that is to say negative influences due to the high concentration of pollutants, or other influences of the untreated exhaust gas on this upstream control sensor. The upstream control sensor thus changes its measuring behavior so that the dynamic vibration behavior is still well recorded, however, without the trim probe for a longer period of use of the upstream control sensor, no exact statements about the (average) lambda value itself are possible. In chemical equilibrium, the lambda value results directly from the oxygen partial pressure. Therefore, the lambda value and thus also the oxygen storage capacity of the catalyst can be determined by measuring the oxygen partial pressure with the second oxygen sensor (trim probe) arranged downstream of the catalyst. A "slow" correction routine can now be installed, which compensates for the aging / poisoning of the upstream control sensor. The course of the oxygen partial pressures determined with the oxygen sensors or other parameters that describe the exhaust gas composition also provides information about the effectiveness or the extent of the combustion The values generated in this way can thus also be used to control the lambda of the internal combustion engine, for example influencing the composition of a fuel-air mixture, the ignition point, the pressures prevailing during combustion, etc.

Another problem with the use of such oxygen sensors or other control probes is their sensitivity to water. If the sensitive area of the control probe comes into contact with water, the functionality of the control probe is generally no longer guaranteed. For this reason, a large number of different configurations of control probes or lambda probes have been proposed which are intended to prevent contact of the sensitive area with water. Such oxygen sensors or lambda probes are usually brought to operating temperature by means of an electrical heating conductor structure. It is also known to provide special shields, grids or coatings that act as a resistance to water. Due to the fact that these probes or sensors are in contact with the exhaust pipe or are passed through them, they generally have a lower temperature than the exhaust gas. It must also be taken into account that the temperature of the gases varies greatly due to the different operating states of the internal combustion engine. There is therefore always a risk that the sensor or the housing surrounding the sensor will reach temperatures that can result in condensation of water from the exhaust gas.

Proceeding from this, it is an object of the invention to provide a simplified method for regulating a fuel mixture with a control probe in the exhaust system of a mobile internal combustion engine. In particular, the problems described with reference to the prior art are to be at least partially alleviated. In addition, an inexpensive and simply constructed exhaust system is to be proposed.

These objects are achieved with a method for regulating a fuel mixture with the features of patent claim 1 and an exhaust system with the features of the independently formulated device claim. Further advantageous embodiments of the invention are described in the respective dependent claims. In addition, it should be pointed out that the features listed individually in the patent claims can be combined with one another in any technologically meaningful manner and show further refinements of the invention.

To regulate a fuel mixture of a mobile internal combustion engine, a control probe is provided in the exhaust system, the exhaust system comprising at least one catalytic converter in an exhaust pipe. The method is characterized in that the control is carried out with a single control probe inside the at least one catalyst.

First of all, the invention says goodbye to the idea of the professional world of having the fuel mixture of the curbing fuel mechanism regulated by means of a plurality of control probes (one for dynamic lambda oscillation and one for slow trimming). This allows the implementation Realize the rank of the method with lower costs and electronics, automatically reducing the susceptibility to malfunction of the system for controlling the fuel mixture. To protect against condensed water, the aggressive environmental conditions caused by the untreated exhaust gas and the high temperature fluctuations, a control probe is placed inside the at least one catalytic converter. This means in particular that parts of the control probe extend into inner regions of the catalytic converter. It is clear that the control probe has to be led out of the exhaust system or the exhaust gas line so that the control probe is not completely arranged inside the catalytic converter. The catalytic converter itself represents a type of attenuator for the temperatures, pollutant concentrations, etc. In particular, it is a thermal mass, so that the thermal behavior is somewhat slower. In this respect, the fluctuations in the exhaust gas temperature as a result of different operating states of the internal combustion engine do not have the same effect on the control probe as would be the case with a control probe that projects freely into the exhaust gas line. The control probe is preferably an oxygen sensor or a so-called lambda probe.

Investigations have shown that the integration of the individual control probe in the catalytic converter guarantees surprisingly exact results over a long operating time. It was found that the effects of the exhaust gas (eg temperature fluctuations, pressure fluctuations, etc.) already decrease considerably over the first millimeters of the catalytic converter, so that a significant “aging or The control probe has been implemented to protect against poisoning. For this purpose, more detailed information is given below. At the same time, there is sufficient lambda oscillation that can be used for the lambda control of the internal combustion engine. Appropriate control probe types are advantageously used in such a configuration For example, in a range up to a 50% reduction in the lambda vibration "arriving" at the catalyst, so-called jump probes (eg zirconium dioxide probe with a sudden change in the output signal with a lambda value of approximately 1) can be used, as these are particularly inexpensive and still sufficiently sensitive. In the case of a further reduction in the lambda vibration amplitudes, for example down to 5%, so-called linear probes should preferably be used.

At this point it should be pointed out that this does not mean that no further sensors may be provided in the exhaust system at all. For example, nitrogen oxide sensors can be connected downstream of the catalyst, which determine the nitrogen oxide concentration in the exhaust gas after contact with the catalyst. However, the measurement values obtained in this way are not used for lambda control of the internal combustion engine.

According to a further embodiment of the method, the control probe is heated after the start-up of the internal combustion engine in such a way that it has a temperature of at least 70 ° C. [degrees Celsius] before the at least one catalyst has reached 95 ° C. The control probe can be heated passively (essentially only by the temperature of the exhaust gas coming into contact with it) and / or actively (for example by a heating element, an electrical heater, etc.). As already mentioned at the beginning, control probes of this type usually have a particular sensitivity to water. It is now proposed here that the control probe has a temperature of at least 70 ° C (at which the phenomenon of condensation no longer takes place to a substantial extent due to the arrangement proposed here in the catalytic converter) before the catalytic converter has reached 95 ° C. In addition to a thermal mass, the catalyst also provides a large surface that can be used for the accumulation of water or water vapor. In other words, this means that the catalyst or in particular its coating acts like a sponge for water and binds it for a relatively long time.

When the internal combustion engine is (re) started, the exhaust gas flowing through the catalyst heats the catalyst carrier body and the coating gradually. A temperature profile is formed in the catalytic converter in the flow direction of the exhaust gas, so that the exhaust gas inlet side initially has the highest temperatures and then decreases in the flow direction. In particular, it is now proposed here that the control probe already has a temperature of at least 70 ° C., in particular at least 90 ° C. [degrees Celsius], before the catalytic converter or the catalytic converter carrier body is in one plane parallel to the exhaust gas inlet side with a Distance of 10 mm has reached a temperature of 95 ° C. In an area above averaged 95 ° C, the stored water evaporates increasingly and propagates in the direction of flow of the catalyst, where it condenses again when it encounters colder areas. A kind of "water vapor front" is thus generated through the catalytic converter. Ensuring a certain temperature of the control probe ensures that the control probe does not represent such a heat sink on contact with the water vapor front that condensation of water occurs here the functionality of the individual control probe is guaranteed.

In particular, it is proposed that the control probe determine at least one of the following components of the exhaust gas: hydrocarbon, carbon monoxide, oxygen. In addition, it is also possible to use this control probe to record a partial pressure, a temperature or other physical measured variables.

According to a further embodiment of the method, the control probe is a lambda probe, which is used at the same time to check the convertibility of the at least one catalytic converter. In particular, it is a so-called broadband lambda probe (lambda probe) which, depending on the oxygen content in the exhaust gas in the range around lambda = 1 (for example with a tolerance of +/- 0.005), provides a constant, e.g. B. linear, output signal. With this signal, the mixture is regulated according to the setpoint specifications. In the embodiment of the control probe proposed here, it is possible to place it relatively far behind in the catalytic converter, in particular with a a distance of 25 mm to 60 mm. In this area, the lambda vibrations are often reduced or smoothed by more than 50%, sometimes even by more than 90%. Nevertheless, the use of such a broadband lambda probe still allows a high level of measurement accuracy, and its position in the catalytic converter results in an extremely low tendency to poisoning, so that an average lambda value can also be determined precisely and over a long period of time. The oxygen content determined with the lambda probe can also be used as a measure of the convertibility of the catalytic converter. With regard to this process, reference is made to the explanations given at the beginning. With such a lambda probe, onboard diagnosis can be carried out easily. This specifies a method which is particularly simple and at the same time enables lambda control of the internal combustion engine and onboard diagnosis.

It is also proposed that the exhaust gas generated by the combustion engine is mixed in the exhaust line before it reaches the control probe. Due to the position or position of the control probe in the exhaust pipe, only certain edge flows of the exhaust gas would always be recorded and evaluated. To ensure that a result that is representative of the entire exhaust gas flow is obtained, the exhaust gas flow is mixed before it reaches the control probe. It can then be assumed that the position of the individual control probe with respect to the exhaust pipe does not have a significant negative impact on the result of the measurement. Separate flow mixers (static or dynamic) and / or also special configurations of the catalysts and / or other exhaust gas treatment devices can be provided for mixing the exhaust gas.

According to a further embodiment of the method, the at least one is used

Catalyst for treating at least one of the following components of the exhaust gas: hydrocarbon, carbon monoxide, nitrogen oxide, particles. In particular, it is a metallic catalyst carrier body or a ceramic honeycomb structure which is provided with a coating which acts catalytically on at least one of the above-mentioned components and contributes to their implementation. In addition to the catalytic function, the catalyst can also have adsorbing and / or filtering and / or other functions, for example. The coating is advantageously neutral to oxygen so as not to negatively influence the measurement result.

According to a further aspect of the invention, an exhaust gas system comprising a mobile internal combustion engine with at least one exhaust gas line, in which at least one catalytic converter is provided, as well as a control probe and an associated control unit for controlling the fuel mixture for the internal combustion engine are proposed. The exhaust system here has only a single control probe inside the at least one catalytic converter. The measurement results of the control probe are evaluated by the control unit and, depending on the target specifications stored there, the composition of the fuel mixture, but possibly also the ignition timing, the injection pressures, etc. is varied. The system of an upstream control probe and a downstream trim probe is thus again dispensed with and replaced by a system comprising a single control probe which projects into the inner regions of the at least one catalytic converter. This significantly reduces the susceptibility to faults, the technical effort and the costs.

According to a development of the exhaust system, the control probe is arranged at a distance of 10 mm to 80 mm from an exhaust gas inlet side of the at least one catalytic converter. Experiments have shown that, depending on the internal combustion engine, the distance specified here is sufficient to ensure that when the internal combustion engine is cold started and the control probe is electrically heated at the same time, the control probe has a temperature above 70 ° C. before it starts from that described above Water vapor front is reached. The control probe is advantageously positioned at a distance of 25 mm to 60 mm from the exhaust gas inlet side. It is also proposed that the control probe is a heatable lambda probe. While it is fundamentally possible for the control probe to be brought to the required temperature after the cold start solely by the exhaust gas flowing past, it is advantageously proposed here that the lambda probe can be heated, in particular by means of an electrical heating conductor structure which is integrated in the lambda probe , When the internal combustion engine starts, current is applied to this heating conductor structure, so that the subcomponents of the lambda probe that protrude into the exhaust pipe and come into contact with the exhaust gas are quickly brought to temperatures above 70 ° C.

In addition, it is also proposed that in at least one area of the at least one catalytic converter between an exhaust gas inlet side and the control probe, means are provided for reducing a rate of propagation of water or water vapor. This means in particular that the water or water vapor cannot move through the area of the catalytic converter at the same speed as the exhaust gas. Some of these options for reducing the rate of spread of water or water vapor are described in the following paragraph.

Accordingly, at least one area of the at least one catalytic converter is designed between an exhaust gas inlet side and the control probe with channels and at least one of the following features: channel density from 600 to 1200 cpsi [cells per square inch]; Openings in channel walls of the channels; Mischerstrakturen; porous surface of the channels; Coating with a storage capacity for at least water or water vapor; metallic channel walls with a thickness in the range from 40 μm to 110 μm (micrometer).

The design of a catalyst with channels is known. These are preferably so-called honeycomb bodies which have a multiplicity of channels arranged essentially parallel to one another. Basically, the channels can be formed by metallic or ceramic channel walls.

A “channel density” is understood to mean the number of channels per unit cross-sectional area of the catalytic converter or honeycomb structure. “Cpsi” refers to the “cells per square inch” unit commonly used in this technical field. 1 cpsi corresponds to in The range from 600 cpsi to 1200 cpsi is relatively high and represents a very large surface area as well as a relatively high thermal mass in this area, which on the one hand creates a large contact area for water or water vapor and on the other hand, at the same time, a relatively high heat capacity is provided, so that here, especially in the cold start phase of the combustion engine, the water or water vapor is well bound or stopped.

The provision of openings in the channel walls means that partial exhaust gas streams flowing through the individual channels can be mixed. This results in a temperature or concentration compensation of the exhaust gas over the cross section of the catalytic converter, so that the control probe enables a characteristic measured value for the entire exhaust gas flow regardless of its position in the exhaust system.

To support this mixing effect, it is proposed that mixer structures be provided in the at least one area. Mixer structures are to be understood in particular as elevations, guide surfaces, etc., which at least partially protrude into inner areas of the channels or onto others Wise differences in flow or flow deflections. They force the partial exhaust gas flows to neighboring channels, so that sufficient mixing of the partial exhaust gas flows is ensured. A porous surface of the channels offers sufficient attachment or storage options for water or water vapor. Porous surfaces or materials of the channel walls themselves are meant in particular, for example also of the catalyst support body or the honeycomb structure. In addition, the channels or their surface can be provided with a coating which has a storage capacity for at least water or water vapor. That means, for example, that you are hygroscopic. This delays the spread of the water vapor front, so that the control probe is provided with the time it needs to reach the appropriate temperatures. It may be advantageous if the storage capacity in the upstream area is greater than in a section downstream of the control probe.

As a further measure, it is also possible for the catalyst to be constructed with a metallic catalyst carrier body. In this case, metallic channel walls with a thickness in the range from 40 μm to 110 μm (micrometers) are preferred. These, in turn, provide the favorable high heat capacity, which hinders the rapid evaporation of accumulated or stored water.

Basically, it should be noted that it is advantageous to combine at least two of the above-mentioned features with one another.

According to a further development of the exhaust system, the control probe has a coating with at least one storage capacity for at least water or water vapor or a catalytic activity towards at least one component of the exhaust gas. In an advantageous embodiment, the coating has both capabilities. come on. The storage capacity is preferably up to a temperature at which the catalytic activity starts.

In addition, it is also proposed that the exhaust system, as described above according to the invention, be included in a vehicle. By vehicle is meant in particular a passenger car, a truck, a motorcycle, a motor boat, a motor plane, etc.

Independently of the control probes described so far, a sensor, in particular the lambda sensor, can be provided with a protective cap, which advantageously protects the sensor against water hammer. Water hammer is the impact of drops of water on the sensor or the condensation of water vapor on it. The function, in particular of lambda sensors, is at least impaired by water hammer, the probe can even become completely unusable by water hammer.

The water hammer can be prevented in an advantageous manner if the protective cap heats up faster than the honeycomb structure or the honeycomb body in which the sensor is inserted. The protective cap preferably has such a temperature as quickly as possible that condensation of water vapor on the surface of the sensor is reliably avoided. This is achieved, for example, by the protective cap being formed from a material which has a significantly lower heat capacity, in particular specific heat capacity, than the material from which the honeycomb body is made. A substance with such a specific heat capacity is preferably selected that, in the normal operating state, it is ensured that when the honeycomb body has a temperature above the boiling point of water in the direction of flow in front of the sensor, the protective cap also has a temperature above the boiling point of water and This is true even if the honeycomb body still has a temperature below the boiling point immediately adjacent to the sensor in the flow direction upstream. Is alike it is advantageous that when the honeycomb body has a temperature above the boiling point of water in the flow direction upstream of the sensor, the heat capacity, in particular specific heat capacity, of the protective cap is selected such that it has such a temperature that the dew point of water under normal operating conditions on the sensor or the protective cap is reliably avoided and thus condensation of the water on the sensor or the protective cap is effectively avoided.

Another possibility of forming a corresponding protective cap is to change the heat transfer coefficient of the protective cap. By adapting this heat transfer coefficient, it can also be achieved that the measuring sensor or the protective cap quickly reach such a temperature that the condensation of water vapor, which arises from evaporation within the honeycomb body, is effectively prevented. The protective cap can be formed as a separate component or also integrally on the sensor. The protective cap can also be combined with the control probes according to the invention.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the figures z. T. show particularly preferred embodiments of the invention, but this is not limited thereto. Show it:

1 schematically shows a vehicle with an exhaust system;

2 schematically shows a catalytic converter with a control probe;

Fig. 3 shows schematically a catalyst in cross section;

4 schematically shows a further embodiment of a catalytic converter; FIG. 5 shows a detailed view of the catalytic converter from FIG. 4;

6 schematically shows a diagram relating to the measurement quality of the control probe as a function of the position relative to the catalytic converter; and

Fig. 7 schematically shows the structure of a control probe.

1 shows schematically and in perspective a vehicle 17 with an internal combustion engine 3 and an associated exhaust system 2. In particular, diesel and gasoline engines can be provided as the internal combustion engine 3. The exhaust gas generated by the engine 3 is emitted to the environment via the exhaust line 5. For this purpose, the exhaust gas is brought into contact with exhaust gas treatment devices such as, for example, catalysts, adsorbers, particle traps, etc., pollutants in the exhaust gas being at least partially converted into at least less harmful components.

In FIG. 1, the exhaust gas first flows through a mixer 20 before it is fed to a catalytic converter 4. The catalytic converter 4 is equipped with a control probe 1 for regulating the fuel mixture or for onboard diagnosis of the catalytic converter 4, which protrudes into the inner areas of the catalytic converter 4. The control probe 1 is connected to a control unit 6, in particular the engine control. The control unit 6 now varies the composition of the fuel mixture depending on the parameters detected by the control probe 1 and the specifications stored there.

FIG. 2 schematically shows a catalytic converter 4 with a control probe 1. The control probe 1 is introduced through the exhaust pipe 5 into inner areas of the catalytic converter 4. The catalytic converter 4 is designed here with a housing 18 in which a honeycomb structure through which the exhaust gas can flow is provided. The honeycomb structure is formed by a multiplicity of channel walls 12, which provide channels 10 through which the exhaust gas can flow. The exhaust gas flows in flow direction 19 and hits the exhaust gas inlet side 8. A region 9 is provided between the exhaust gas inlet side 8 and the control probe 1, which area is used to prevent the speed of propagation from occurring when the internal combustion engine is (re) started. the catalyst 4 has reproductive water vapor front. To ensure that after a cold start, control probe 1 has reached temperatures above 70 ° C before this water vapor front has reached control probe 1, control probe 1 is positioned at a distance 7 of 10 to 80 mm. It should be pointed out here that the distance 7 shown here is shown schematically, that is to say nothing about the ratio of the total length of the catalyst 4 in the direction of the flow direction 19.

3 shows a further embodiment of a catalytic converter 4 in cross section. The catalytic converter 4 in turn has a housing 18 and an area 9 which extends over a distance 7 from the exhaust gas inlet side 8. The catalyst 4 has a metallic catalyst carrier body, so that the channel walls 12 are of metallic origin.

Within the area 9, the channels 10 are delimited by channel walls 12 which have a greater thickness 16 than other areas of the catalytic converter. At the same time, openings 11 and mixer structures 13 are provided which enable adjacent partial exhaust gas flows to be mixed. This can ensure that the control probe 1 to be inserted into the recess 23 can deliver qualified results with regard to the exhaust gas composition there.

Downstream of the area 9, the channels are delimited by thinner channel walls 12, it being possible for the surface 14 to also have a coating 15, for example. In the embodiment shown here, the channel walls 12 are also provided with openings 11 in the downstream region. The different areas 9 of the catalytic converter 4 can if also formed by different, separate honeycomb structures or carrier bodies (possibly spaced apart with a gap).

4 and 5 show yet another embodiment of a catalytic converter 4 with a control probe 1. The catalytic converter 4 here in turn has a housing 18, the internal honeycomb structure being formed by smooth foils 21 and corrugated foils 22 which are involute-shaped and intertwined with one another are soldered (especially high temperature soldered). From the front view it can be seen that the smooth foils 21 and the corrugated foils 22 each form layers 24, it being possible for the adjacent channels 10 to also be mixed within these layers 24. In the detailed view (FIG. 5) it can be seen that the smooth foils 21 and the corrugated foils 22 are positioned alternately to one another and thus form channels 10. A catalytically active coating 15 is provided on the surface 14 of the channels 10.

6 schematically shows a diagram relating to the measurement quality of the control probe as a function of the position relative to the catalytic converter. The abscissa shows, for example, the distance 7 of the control probe 1 from the exhaust gas inlet side 8 in millimeters. The ordinate shows an example of the reduction in the lambda control oscillation in percent. The result of this is that after just a few millimeters, for example 10 mm, there is already a significant reduction in the lambda vibration, in particular by at least 50%. For example, there may be reductions of more than 80% at a distance of 40 mm or even 95% at a distance of 60 mm. The curve 25 shown is schematic and is intended to illustrate the course. In order to obtain a measurement result that is sufficiently precise for the lambda control, it is proposed here that different embodiments may be selected depending on the position of the control probe. For this purpose, a limit value 26 was drawn in, which can be regarded as a measure of the sensitivity of the control probe. The area marked with "I" is intended to characterize the area of application for a jump probe, the area marked with "II" is intended to characterize that of a broadband linear probe. This shows that e.g. up to a distance of about 20 mm (in other cases also up to 40 mm) a jump probe is advantageous (low cost, sufficiently precise) and at a distance above it the broadband linear probe should be used for control.

Fig. 7 shows schematically the structure of a control probe 1 in an installed position, the control probe 1 described below being a particularly preferred embodiment, which may also be used as the sole control probe 1 e.g. can be used behind a catalyst 4. It has a nut 27 and a threaded section 28 for fixing to the housing 18. The sensitive area 29 now protrudes into a recess 23 in the catalytic converter 4, the channel walls 12 forming the channels 10.

Because of the protective measures described above for the sensitive area 29 by means of the catalyst 4 as an attenuator (for example regarding the temperatures, pollutant concentrations, pressure fluctuations, water content in the exhaust gas), the control probe 1 can be exposed directly to the exhaust gas flow, and the protective cap normally used can therefore be dispensed with , However, for reasons of protection of the sensitive area 29 during storage, transportation, assembly, etc., it may be necessary to provide a cap 30. However, this is designed so that it has a particularly low heat absorption capacity, in particular less than 1 J / K [joule per Kelvin] or even less than 0.8 J / K. This can be achieved, for example, by a particularly thin-walled cap 30, a porous cap 30, a cap 30 having many openings 32, a very small cap 30, etc. This cap 30 is preferably made of a steel material and is produced in particular by means of a forming manufacturing process (eg deep drawing). In addition, guide surfaces 31 can be provided, which allow a suitable flow of the exhaust gas to the sensitive area 29 and possibly also result in a longer residence time of the exhaust gas in the interior of the cap 30. In the event that the cap 30 is at least partially coated, this refers to the above parameter on the cap 30 including the coating. Such an embodiment of the control probe 1 can also advantageously be used independently of the control method described here, in particular with an exhaust gas system in which this control probe 1 is arranged downstream of a catalytic converter 4.

LIST OF REFERENCE NUMBERS

Control system exhaust system

Internal combustion engine

catalyst

exhaust pipe

control unit

distance

Exhaust gas inlet side

Area

channel

opening

channel wall

mixer structure

surface

coating

thickness

vehicle

casing

flow direction

mixer

smooth foil

corrugated foil

recess

location

Curve

limit

mother

threaded portion

Area Cap guide surface opening

Claims

claims

1. A method for controlling a fuel mixture with a control probe (1) in the exhaust system (2) of a mobile internal combustion engine (3), the exhaust system (2) comprising at least one catalyst (4) in an exhaust line (5), characterized in that the Regulation with a single control probe (1) inside the at least one catalyst (4) is carried out.

2. The method according to claim 1, characterized in that the control probe (1) after starting the internal combustion engine (3) is heated so that it has a temperature of at least 70 ° Celsius before the at least one catalyst (4) 95 ° Celsius has reached.

3. The method according to claim 1 or 2, characterized in that the control probe (1) determines at least one of the following components of the exhaust gas: hydrocarbon, carbon monoxide, nitrogen oxide, oxygen.

4. The method according to any one of claims 1 to 3, characterized in that the control probe (1) is a lambda probe, which is used at the same time to check the convertibility of the at least one catalyst (4).

5. The method according to any one of claims 1 to 4, characterized in that the exhaust gas generated by the internal combustion engine (3) is mixed in the exhaust pipe (5) before it reaches the control probe (4).

6. The method according to any one of claims 1 to 5, characterized in that the at least one catalyst (4) for treating at least one of the following The components of the exhaust gas are: hydrocarbon, carbon monoxide, nitrogen oxide, particles.

7. Exhaust system (2) comprising a mobile internal combustion engine (3) with at least one exhaust pipe (5), in which at least one catalytic converter (4) is provided, as well as a control probe (1) and a control unit (6) connected thereto for controlling the fuel mixture for the internal combustion engine (3), characterized in that a single control probe (1) is arranged inside the at least one catalytic converter (4).

8. Exhaust system (2) according to claim 7, characterized in that the control probe (1) is arranged at a distance (7) from an exhaust gas inlet side (8) of the at least one catalyst (4) from 10 mm to 80 mm [millimeters] away ,

9. Exhaust system (2) according spoke 7 or 8, characterized in that the control probe (1) is a heatable lambda probe.

10. Exhaust system (2) according to one of claims 7 to 9, characterized in that in at least one area (9) of the at least one catalyst (4) between an exhaust gas inlet side (8) and the control probe (1) means for reducing a propagation speed of Water or water vapor are provided.

11. Exhaust system (2) according to one of claims 7 to 10, characterized in that at least one region (9) of the at least one catalyst (4) between an exhaust gas inlet side (8) and the control probe (1) with channels (10) and at least one of the following features: - channel density from 600 to 1200 cpsi [cells per square inch]; - Openings (11) in channel walls (12) of the channels (10); - mixer structures (13); - Porous surface (14) of the channels (10); - Coating (15) with a storage capacity for at least water or water vapor; - metallic channel walls (12) with a thickness (16) in the range from 40 μm to 110 μm [micrometer].

12. Exhaust system (2) according to one of claims 7 to 11, characterized in that the control probe (1) has a coating (15) with at least one storage capacity for at least water or water vapor or a catalytic activity with respect to at least one component of the exhaust gas Has.

13. Vehicle (17) comprising an exhaust system (2) according to one of claims 7 to 12.