Method for operating a catalytic device, catalytic device, internal combustion engine, control method for controlling the internal combustion engine, and motor vehicle

Abstract

The invention relates to a method for operating a catalytic device, to a catalytic device, to an internal combustion engine, to a control method for controlling the internal combustion engine, and to a motor vehicle. According to the method, a lambda value (λ) is detected, and a characteristic field weighting factor (K) is ascertained on the basis of the lambda value. Oxygen supply partial values (sa, sb) are ascertained from characteristic fields specified for a detected current operating mode and are weighted using the characteristic field weighting factor (K). The characteristic field-weighted oxygen supply partial values (Sa, Sb) are added to the actual oxygen supply value (SZist), which goes into the total actual oxygen supply value (SZist ges). An oxygen requirement value (mO2 Bedarf) is provided on the basis of the total actual oxygen supply value (SZist ges), the actual oxygen quantity value (mO2 ist), and a target oxygen quantity value (mO2 soll) that characterizes the target oxygen quantity in the catalytic converter with which the catalytic converter operates at the best possible conversion rate.

Description

[0001] 22-3450 1 Method for operating a catalytic converter device, catalytic converter device, internal combustion engine, control method for controlling the internal combustion engine, and motor vehicle The present invention relates to a method for operating a catalytic converter device for an internal combustion engine, said catalytic converter having a catalytic converter. Furthermore, the invention relates to a catalytic converter device having means for carrying out the aforementioned method. Furthermore, the invention relates to an internal combustion engine, to which the catalytic converter of the catalytic converter device is connected on the exhaust side, and to a control method for controlling such an internal combustion engine. Furthermore, the invention relates to a motor vehicle having such an internal combustion engine and, consequently, the catalytic converter device.There is a need for particularly efficient aftertreatment of exhaust gases emitted during operation of an internal combustion engine in order to minimize pollutant emissions into the environment. Lambda-controlled catalysts are known for this purpose. The highest possible conversion rate is achieved with the catalyst when it is operated within a narrow range around a combustion stoichiometric air / fuel ratio (λ^=^1), the so-called lambda window. For this purpose, it is helpful to know the current oxygen loading of the catalyst during operation.In this context, DE 102004009615 A1 proposes a method for determining the current oxygen loading of a three-way catalytic converter of a lambda-controlled internal combustion engine. A value for the current oxygen loading is calculated from a pre-catalytic converter lambda sensor signal and a measured air flow rate by integration over time. This value is initialized upon signal breakthroughs of a post-catalytic converter lambda sensor. At the time of such a signal breakthrough of the post-catalytic converter lambda sensor, however, an unfavorable combustion air ratio already exists, so that the resulting exhaust gas flows into the environment downstream of the catalytic converter untreated or only slightly treated, i.e., rich in pollutants. The object of the invention is to improve the efficiency of a catalytic converter device for an internal combustion engine.to reduce the amount of exhaust gas that exits the catalytic converter device untreated or with only minimal treatment. This object is achieved by the subject matters of the independent patent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description and the figures. Features, advantages and possible embodiments that are set out in the description for one of the subject matters of the independent claims are to be regarded, across categories and embodiments, at least analogously as features, advantages and possible embodiments of the respective subject matter of the other independent claims and of any possible combination of the subject matters of the independent claims, optionally in conjunction with one or more of the subclaims. According to the invention, a method for operating a catalytic converter device for an internal combustion engine that has a catalytic converter is proposed.With the aid of the method, an oxygen demand value mO2 demand is provided which characterizes an oxygen supply that is to be supplied to the catalyst in order to set a target oxygen quantity in the catalyst at which the catalyst operates at the best possible conversion rate. Furthermore, the invention proposes a catalyst device that has the catalyst and is configured to carry out the method for operating the catalyst device. In the intended installation position, the catalyst device forms a component of the internal combustion engine according to the invention, to which the catalyst is connected on the exhaust side. The internal combustion engine, in particular an engine control unit of the internal combustion engine, accepts the oxygen demand value mO2 demand determined by means of the method as a control signal.As a result, the internal combustion engine can be controlled such that it provides an oxygen supply, by means of which the target oxygen quantity is set in the catalytic converter. In the control method according to the invention for controlling the internal combustion engine, it is controlled such that it provides an oxygen supply, by means of which the target oxygen quantity is set in the catalytic converter. The invention also proposes a motor vehicle which has the internal combustion engine and consequently the catalytic converter device. The method according to the invention for operating the catalytic converter device can be a computer-implemented method. The catalytic converter device is then configured to carry out the method. For this purpose, the catalytic converter device has, in particular, a catalytic converter control unit.The invention then further proposes a first computer program which, when its program instructions are executed by the catalytic converter device, in particular by its catalytic converter control unit, causes the catalytic converter device to execute the method for operating the catalytic converter device. Furthermore, the control method for controlling the internal combustion engine can be a computer-implemented method. In this case, the internal combustion engine is configured to execute the method. For this purpose, the internal combustion engine has, in particular, the engine control unit. A second computer program is then proposed according to the invention, wherein, when the program instructions of the second computer program are executed by the internal combustion engine, in particular by its engine control unit, the internal combustion engine is controlled according to the control method for controlling the internal combustion engine.The invention further proposes a computer-readable storage medium on which the first computer program and / or the second computer program are / or are stored. In the method according to the invention for operating the catalytic converter device, an active operating mode of the internal combustion engine is detected in a step S1 during a detection time period which, for example, has a predetermined duration of 10 ms (milliseconds). Thus, for example, it is detected whether the internal combustion engine is operating in a "dynamic load buildup" operating mode, a "safe combustion" operating mode, or a "consumption-optimized" operating mode. A mixed operating mode comprising two or more operating modes is conceivable, which will be discussed in more detail below.Each possible operating mode is assigned three load-speed maps belonging to the corresponding operating mode, namely one for λ^=^1 (combustion stoichiometric), one for λ^<^1 (lean) and one for λ^>^1 (rich). The maps represent, for example, a lambda range from λ^=^1.1 (inclusive) to λ^=^0.9 (inclusive) 22-3450 4. The content of the respective load-speed map is determined, for example, using test bench measurements and calculations of chemical reactions in the catalytic converter. The maps provide information as to whether oxygen is being introduced into or removed from the catalytic converter during operation of the internal combustion engine. For the further process, a lambda value λ is recorded in a step S2, which can be carried out before, during or after step S1.To determine the lambda value, the method specifically examines whether a measurement signal from a pre-catalyst lambda sensor located between the internal combustion engine and the catalytic converter in the exhaust system is considered reliable. If this is the case, the lambda value is measured using the pre-catalyst lambda sensor. If, however, it is determined that the measurement signal from the pre-catalyst lambda sensor is to be assumed to be unreliable, for example due to a defect, insufficient operating temperature, etc., the lambda value is determined using a target lambda value determined by an engine control unit of the internal combustion engine. Based on the determined lambda value λ, a characteristic map weighting factor K is determined in step S3.1 of the method.In one possible embodiment of the method, the map weighting factor K is determined using a predefined weighting characteristic curve, wherein the map weighting factor K is at least 0 and at most +1 (0^≤^K^≥^1). The weighting characteristic curve establishes a relationship between the detected lambda value λ and the map weighting factor K. In particular, the graph of the weighting characteristic curve is formed at least in a characteristic curve portion of the weighting characteristic curve according to the following equation (see Fig. 2 - graph 7a of characteristic curve 7): for ^^ < 0.9 for 0.9 ≤ ^^ < 1 for 1 ≤ ^^ ≤ 1.1. for ^^ > 1.1 The weighting characteristic can be formed from at least one odd or non-linear characteristic instead of linear characteristic components, for example, at least part of a parabolic graph, a hyperbolic graph, a graph of a logarithmic function, a graph of an exponential function, a graph of an inverse function, an oval (special case ellipse, special case circle), etc. In addition, a weighting characteristic is conceivable that has both at least one linear characteristic component and at least one non-linear or odd characteristic component. Furthermore, in a step S3.2, a first oxygen supply partial value s is determined from the load-speed characteristic map for λ^=^1 assigned to the detected operating mode. a The first oxygen supply partial value s aDepending on its sign, it characterizes an oxygen input into the catalyst or an oxygen output from the catalyst. The first oxygen input partial value s a is also calculated in step S3.2 with the map weighting factor K, in a possible embodiment of the method multiplied, from which a first map-weighted oxygen supply partial value S a results: ^^ ^^ = ^^ ^^ ⋅ ^^ In step S3.3 of the method, a second oxygen supply partial value s b determined, namely, if the recorded lambda value λ is greater than 1, from the characteristic map for λ^>^1 assigned to the recorded operating mode, or, if the recorded lambda value λ is less than 1, from the characteristic map for λ^<^1 assigned to the recorded operating mode. Analogous to the first oxygen supply partial value s a characterizes the second oxygen supply partial value s bDepending on its sign, an oxygen input into the catalyst or an oxygen output from the catalyst. If, for example, the lambda value λ^=^1.01 is recorded in step S2, the second oxygen input partial value s b taken from the map for λ^>^1 (step S3.3.1). If, however, in step S2, for example, a lambda value λ^=^0.96 is recorded, the second oxygen supply partial value s b taken from the characteristic map for λ^<^1 (step S3.3.2). Step S3.3.1 or S3.3.2 is followed by a further step S3.4, in which the second oxygen supply partial value s b is offset against the map weighting factor K, resulting in a second map-weighted oxygen supply partial value S bresults. In one possible embodiment of the method, the second oxygen supply partial value sb is multiplied by a difference whose minuend is 1 and whose subtrahend is the map weighting factor K, in order to obtain the map-weighted oxygen supply partial value Sb: ^^ ^^ = ^^ ^^ ⋅ (1 − ^^) If the lambda value is exactly λ^=^1, the map weighting factor K^=^1, whereby the second oxygen supply partial value s b ^= 0. In such a case, the first 22-3450 6 oxygen supply partial value s a weighted with 100^% and the second oxygen supply partial value s b with 0^%. The map-weighted oxygen supply partial values ​​S a , S b are converted in a step S4 of the method into an actual oxygen supply value SZ characterizing an actual oxygen supply of the catalyst istof the recording time period. In this way, an oxygen supply to the catalytic converter or an oxygen removal from the catalytic converter can be determined for each recording time period without the aid of a post-catalyst lambda probe (also called a trim probe). This advantageously also takes into account catalytic reactions in a raw exhaust gas, which behave differently depending on the operating mode and / or operating point of the internal combustion engine at the same lambda value. In a method step S5, a total actual oxygen supply value SZist ges, which has the actual oxygen supply value SZist, is recorded, and in a method step S6, an actual oxygen quantity value mO2 ist is recorded, which characterizes an actual oxygen quantity, for example an actual oxygen mass, that is currently stored in the catalytic converter.The total actual oxygen supply value SZist ges thus has the actual oxygen supply value SZist for one run of the method up to this point, in particular for a respective recording time period; the determined actual oxygen supply value SZist is passed on to a further step of the method, for example in the form of the total actual oxygen supply value SZist ges. As will be described further below, the total actual oxygen supply value SZist ges can be added together in step S5 from two or more actual oxygen supply values ​​SZist. The actual oxygen quantity value mO2 ist is recorded in step S6, for example, by adding the total actual oxygen supply value SZist ges to an oxygen quantity output value m0 of the catalyst.In a step S7, the oxygen demand value mO2 demand is determined based on the total actual oxygen supply value SZist tot, the actual oxygen quantity value mO2 actual, and a target oxygen quantity value mO2 target, which characterizes the target oxygen quantity, for example a target oxygen mass, in the catalytic converter at which the catalytic converter operates at the best possible conversion rate. This characterizes an oxygen supply that - depending on the sign of the oxygen demand value mO2 demand - is to be supplied to the catalytic converter or removed from the catalytic converter in order to set the target oxygen quantity in the catalytic converter at which the catalytic converter operates at the best possible conversion rate. Therefore, if the target oxygen quantity is present in the catalytic converter, it is operated with a combustion stoichiometric combustion air ratio (λ^=^1), the so-called lambda window. In 22-3450 7 a step S8 the oxygen demand value m. O2 Bedarfprovided, for example, to another control unit and / or output in another way. In particular, the oxygen demand value m O2 BedarfThe method for operating the catalytic converter improves the efficiency of a catalytic converter for an internal combustion engine, allowing the internal combustion engine or the motor vehicle incorporating the internal combustion engine to operate with particularly low emissions. This is because the amount of exhaust gas that exits the catalytic converter untreated or with only minimal treatment is reduced, while requiring very little computing power from the computers or control units involved.Due to the method, determining an oxygen demand in the catalytic converter is no longer accompanied by measuring a lambda value downstream of the catalytic converter (trim probe deflection), but is determined using the method presented here, without the trim probe deflection frequently occurring due to the outflow of poorly treated exhaust gas from the catalytic converter. In a further possible embodiment of the method, steps S1, S2 are carried out as described above. In step S3.1, a map weighting factor K is then determined based on the detected lambda value λ. In particular, the map weighting factor K is determined using a predetermined weighting characteristic, whereby the map weighting factor K here is at least −1 and at most +1 (−1^≤^K^≥^+1). The weighting characteristic is then mapped in particular according to the following equation (see Fig.2 – Graph 7c of the characteristic curve 7): −1 for ^^ < 0,9 ^^ = { ( ^^ − 1) ⋅ 10 for 0,9 ≤ ^^ ≤ 1,1 1 for ^^ > 1,1 The first partial oxygen supply value s. a is multiplied in step S3.2 according to this embodiment of the method by a difference whose minuend is 1 and whose subtrahend is the amount of the map weighting factor K, from which the first map-weighted oxygen supply partial value S a results: ^^ ^^ = ^^ ^^ ⋅ (1 − | ^^|) 22-3450 8 Steps S3.3, S3.3.1 and S3.3.2 then follow as described above. After step S3.3.1 or S3.3.2, step S3.4 follows, in which, according to this embodiment of the method, the second oxygen supply partial value s b is multiplied by the value of the map weighting factor K, from which the second map-weighted oxygen supply partial value S b results: ^^ ^^ = ^^ ^^⋅ | ^^| If the lambda value is exactly λ^=^1, the map weighting factor K^=^0, whereby the second oxygen supply partial value s b ^= 0. This is followed by the steps S4 to S8 described above. According to a possible further embodiment of the method, at least steps S1 to S8 are repeated for a further recording time period or more recording time periods, wherein in the respective step S5 the total actual oxygen supply value SZ ist ges is determined by comparing the actual oxygen supply values ​​SZ ist of the recording time periods over a total duration of the recording time periods to the total actual oxygen supply value SZ ist ges This creates information about how much oxygen the catalyst is loaded with over time or during its operation. Next, in step S6, the actual oxygen quantity value m O2 istrecorded or further developed by adding an actual oxygen quantity value m O2 ist a previous pass of process steps S1 to S6, the total actual oxygen supply value SZ ist ges of the current run. This determines how much oxygen the catalyst is loaded with in relation to time. This gives the oxygen demand value m O2 Be- darfcontinuously adjusted and made available during the duration of operation of the catalytic converter. Further steps of the method, in particular steps of further possible embodiments of the method described herein, can be repeated for the further recording time period or for the further recording time periods. In a possible further development, it is provided that before the oxygen demand value mO2 is required for the first time, in particular before the oxygen quantity value mO2 is determined for the first time, a lambda deflection is detected by means of a post-catalytic converter lambda probe (which can also be referred to as a trim probe) arranged downstream of the catalytic converter in the exhaust system, which lambda deflection characterizes the presence of a defined 22-3450 9 amount of oxygen in the catalytic converter. The deflection of the post-catalytic converter lambda probe characterizes that a defined amount of oxygen is present in the catalytic converter.If the post-catalyst lambda sensor indicates a rich mixture (λ^<^1), it is assumed that there is particularly little oxygen in the catalytic converter; an oxygen quantity initial value m0 is assumed that characterizes a low-oxygen gas mixture in the catalytic converter. If the post-catalyst lambda sensor indicates a lean mixture (λ^>^1), this means that there is particularly high oxygen in the catalytic converter; an oxygen quantity initial value m0 is assumed that characterizes an oxygen-rich gas mixture in the catalytic converter. In step S6, the actual oxygen quantity value m is then determined. O2 ist of the catalyst by calculating the total actual oxygen supply value SZ ist gesand an oxygen quantity output value m0 characterizing the defined oxygen quantity are added. If steps of the method are repeated, it is particularly intended that the oxygen quantity output value m0 is only recorded by means of a single, initial deflection of the post-catalytic converter lambda sensor. During normal operation, in which the internal combustion engine coupled to the catalytic converter device is started by cold start, the post-catalytic converter lambda sensor usually deflects for the first time after one to two seconds. For any repetition of steps of the method during trouble-free normal operation of the catalytic converter, the post-catalytic converter lambda sensor is not used; it then serves merely as a redundant measuring device, for example to detect a malfunction in the operation of the catalytic converter device.The advantage of this development is that a defined initial state of the catalytic converter is recorded, so that the method runs particularly efficiently. This is because estimating a current oxygen quantity in the catalytic converter can be dispensed with for the initial determination of the oxygen quantity value mO2. It can also be provided that the initial deflection of the post-catalytic converter lambda sensor is used as a start signal for the method, whereby the method is not executed until the initial deflection of the post-catalytic converter lambda sensor is recorded. In a further possible embodiment of the method, another active operating mode or two or more active operating modes are recorded. It is therefore recorded that the internal combustion engine is being operated simultaneously in one or more of the operating modes "Dynamic Load Build-Up", "Safe Combustion", "Consumption Optimized" and / or other / further possible operating modes.Each operating mode results in a different composition of the raw exhaust gas. In "Dynamic Load Buildup," the intake valves 22-3450 10 are opened in relation to the combustion chamber of the internal combustion engine while the exhaust valves are still open, so that a portion of the intake air flows out of the combustion chamber via the exhaust valves. This portion of intake air consequently does not participate in combustion in the combustion chamber. In "Safe Combustion," the internal combustion engine is controlled in such a way that—particularly during cold starts or when the interior walls of the combustion chamber are (still) cold—ignition of the fuel-air mixture in the combustion chamber is reliably guaranteed. In "Consumption Optimized," the internal combustion engine is controlled for the most fuel-efficient operation possible.If the internal combustion engine is operated in a mixed operating mode that has two or more active operating modes, steps S2-S4 are executed separately and in parallel for each of the detected active operating modes in the method. Furthermore, especially before step S5, the percentage share of operating mode B1, B2, ..., Bn that the respective operating mode represents in the current overall operation or in the currently active mixed operating mode of the internal combustion engine is recorded. The following applies: The respective actual oxygen supply value SZ ist is then added to the corresponding percentage of the operating mode shares B1, B2, …, B n multiplied, resulting in operating mode weighted actual oxygen supply values ​​SZ ist B1 , SZ ist B2 , …, SZ ist Bn are generated: for the first operating mode: ^^ ^^^^ ^^ ^^ ^^1= ^^1⋅ ^^ ^^ ^^ ^^ ^^ , for the second operating mode: ^^ ^^^^ ^^ ^^ ^^2= ​​^^2⋅ ^^ ^^ ^^ ^^ ^^, for each additional operating mode: ^^ ^^^^ ^^ ^^ ^^ ^^= ^^ ^^ ⋅ ^^ ^^ ^^ ^^ ^^ In step S5, the total actual oxygen supply value SZ ist ges recorded by the operating mode weighted actual oxygen supply values ​​SZ ist B1 , SZ ist B2 , …, SZ ist Bn be added: 22-3450 11 In this way, the oxygen demand value m O2 Bedarf determined particularly accurately, since the composition of the raw exhaust gas is taken into account particularly precisely depending on the operating modes involved. According to a possible further development, the respective percentage share of the operating mode B1, B2, ..., B nAn operating mode characteristic curve is used that was specifically created for the purpose of controlling the catalytic converter device. In particular, the operating mode characteristic curve is not provided by the engine control unit of the internal combustion engine, the motor vehicle, or any other control unit external to the catalytic converter device. Internal investigations have determined that, in order to achieve a particularly advantageous result using the method described herein, the operating modes involved in the overall operation must be weighted differently than is the case with a control of the internal combustion engine.Therefore, although the operating mode weighting determined or set by means of the control of the internal combustion engine can be used for the method, for a particularly efficient and, in particular, rapid adjustment of the target oxygen quantity in the catalytic converter, it has proven more expedient to use the operating mode characteristic curve developed specifically for the method. According to a further possible embodiment of the method, it is proposed that - if a lambda value is detected in step S2 that lies outside the lambda value ranges stored in the load-speed characteristic maps, an extrapolation factor E is determined, in particular from an extrapolation characteristic curve developed specifically for the method. In addition, in steps S3.2 and S3.3, the unweighted oxygen supply partial value sa, sb is determined from the respective characteristic map, which corresponds to the closest lambda value stored in the characteristic map.The extrapolation factor E and the respective oxygen supply partial value sa, sb are then multiplied with one another before step S4, i.e. before the oxygen supply partial values ​​Sa, Sb are added, in particular before the map weighting of the oxygen supply partial values ​​sa, sb. This means that the oxygen supply partial values ​​sa, sb are calculated using the extrapolation factor E if a lambda value is recorded that is not stored in the maps. This is the case, for example, if the load-speed maps do not cover lambda values ​​λ^<^0.9 and / or λ^>^1.1 and a lambda value outside these limits is recorded. Other maps that cover a larger lambda range are of course conceivable. Due to the extrapolation factor E, it is particularly simple orIt is possible to set the target oxygen quantity in the catalytic converter with little effort even if a lambda value is recorded that lies outside the lambda value ranges covered by the characteristic maps. Whether the catalytic converter can absorb oxygen at a given point in time or not depends, among other things, on the amount of oxygen that is already present in the catalytic converter at that time. In order to regulate the oxygen supply to the catalytic converter in such a way that the target oxygen quantity in the catalytic converter is adjusted as quickly and efficiently as possible, a further possible embodiment of the method provides for an uptake correction factor M to be determined based on the oxygen uptake capacity of the catalytic converter. The oxygen uptake capacity of the catalytic converter is determined in particular based on an exhaust gas mass flow and the actual oxygen quantity in the catalytic converter using an uptake capacity characteristic map developed specifically for the method.The following applies to the uptake correction factor M: – if the catalyst is fully capable of absorbing oxygen: M^≥^1, – if the catalyst is partially capable of absorbing oxygen: 0^<^M^≤^1, – if the catalyst is not capable of absorbing oxygen at all: M^=^0. The uptake correction factor M is multiplied by the total actual oxygen supply value SZist ges, so that the total actual oxygen supply value SZist ges is adjusted to the current oxygen uptake capacity of the catalyst. The oxygen demand value mO2 demand is then output or provided in step S8, which takes the adjusted total actual oxygen supply value SZist ges into account. In this way, both oxygen overload and oxygen undersupply of the catalyst are avoided particularly efficiently. In a further possible embodiment of the method, it is taken into account whether the internal combustion engine is operated entirely or partially in overrun mode.For this purpose, an overrun combustion chamber number Z and a combustion chamber-specific overrun oxygen supply value SZZ are determined. The overrun combustion chamber number Z characterizes a number of combustion chambers of the internal combustion engine that are operated in unfired (ignition-free) overrun mode. The combustion chamber-specific overrun oxygen supply value SZZ characterizes the amount of oxygen supplied to the catalyst from exactly one unfired combustion chamber of the internal combustion engine. The overrun oxygen supply value SZ. Z is determined based on an air mass flow that is channeled through an unfired combustion chamber during overrun. In this embodiment of the method, it is further evaluated how the overrun combustion chamber number Z and a total number Z VKMof the combustion chambers of the internal combustion engine are related to each other. If it is determined that the overrun combustion chamber number Z is smaller than the total number Z VKM of the combustion chambers, a combustion chamber correction factor ZK is calculated: The combustion chamber correction factor ZK and the actual oxygen supply value SZist are then multiplied together, resulting in an overrun-corrected actual oxygen supply value SZ ist Z korr results: ^^ ^^^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^= ^^ ^^ ^^ ^^ ^^ ⋅ ^^ ^^ In addition, the combustion chamber-specific overrun oxygen supply value SZZ and the overrun combustion chamber number Z are multiplied with each other, resulting in an actual combustion chamber oxygen supply value SZZ: ^^ ^^^^ ^^ ^^ ^^= ^^ ^^ ^^⋅ ^^ After this, in step S5, the overrun-mode corrected actual oxygen supply value SZist Z korr and the actual combustion chamber oxygen supply value SZZ ist are added to the total actual oxygen supply value SZist ges: ^^ ^^^^ ^^ ^^ ^^ ^^ ^^= ^^ ^^^^ ^^ ^^ ^^+ ^^ ^^^^ ^^ ^^ ^^ ^^ ^^ ^^If, on the other hand, it is detected that the overrun-mode combustion chamber number Z and the total number ZVKM of the combustion chambers are the same, the overrun-mode oxygen supply value SZZ and the overrun-mode combustion chamber number Z are multiplied with one another, from which the total actual oxygen supply value SZist ges results: ^^ ^^^^ ^^ ^^ ^^ ^^ ^^= ^^ ^^ ^^⋅ ^^ The catalyst receives more oxygen from a combustion chamber operated in overrun mode than from a combustion chamber operated with fuel. Therefore, with increasing 22-3450 14 overrun combustion chamber number Z, the amount of oxygen supplied to the catalyst during operation of the internal combustion engine increases. By taking into account whether one or more of the combustion chambers is / are operated in overrun mode, the target amount of oxygen in the catalyst is set even more efficiently. Further features of the invention can be derived from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination, but also in other combinations or on their own, without departing from the scope of the invention.The drawing shows in: Fig.1 a flow chart to illustrate a method for operating a catalyst device for an internal combustion engine having a catalyst, wherein Fig.1 comprises Fig.1a and Fig.1b, Fig.2 a weighting characteristic curve used in the method and Fig.3 a control model characterizing the method, which was generated by means of modeling software for modeling physical systems, in this case Matlab Simulink, wherein Fig.3 comprises Figs.3a, 3b, 3c and 3d.In the following, a method for operating a catalyst device having a catalyst for an internal combustion engine, a catalyst device configured to carry out the method, an internal combustion engine having the catalyst device, a control method for controlling the internal combustion engine and a motor vehicle having the internal combustion engine are explained in a joint description. In the figures, identical and functionally identical elements are provided with the same reference numerals. The catalyst device, internal combustion engine, their control method and the motor vehicle are not shown in the figures. 22-3450 15 With the aid of the method, an oxygen demand value m. O2 Bedarfprovided which characterizes an oxygen supply that is to be supplied to the catalytic converter in order to particularly efficiently set a target oxygen quantity in the catalytic converter in order to operate it as close as possible to a combustion stoichiometric lambda value. In the intended installation position, the catalytic converter device forms a component of the internal combustion engine according to the invention, to which the catalytic converter is connected on the exhaust side. The internal combustion engine, in particular an engine control unit of the internal combustion engine, accepts the oxygen demand value determined by means of the method as a control signal, so that the internal combustion engine is controlled by means of the control method such that it provides an oxygen supply by means of which the target oxygen quantity is set in the catalytic converter. In a step S1 of the method for operating the catalytic converter device, an active operating mode of the internal combustion engine is detected.In the present case, the internal combustion engine is operated in a mixed operating mode, which means that in step S1, two or more simultaneously active, but different operating modes (identified in Fig. 3b with the reference numerals 1, 2, 3) of the internal combustion engine are detected, which overlap or superimpose one another. In other words, in the present example, the internal combustion engine is operated partly in a first operating mode, partly in a second operating mode, and partly in at least one further operating mode simultaneously. The present method also detects which percentage share of the operating mode B1, B2, ..., Bn each operating mode has in the current overall operation or in the currently active mixed operating mode of the internal combustion engine. This can be read out, for example, from an engine control unit of the internal combustion engine.In this example, however, it is provided that the respective percentage operating mode share B1, B2, ..., Bn is taken from an operating mode characteristic curve developed specifically for the method for operating the catalytic converter device. For each operating mode, three load-speed characteristic maps are specified, namely one for λ^=^1, one for λ^<^1, and one for λ^>^1. In step S2, a lambda value λ is recorded. As the lambda value λ, for example – particularly if the method determines that a measurement signal from a pre-catalyst lambda sensor is implausible or unreliable – a target lambda value is used, which is provided, for example, by the engine control unit of the internal combustion engine. 22-3450 16 If, however, the procedure determines that the measurement signal from the pre-catalyst lambda sensor is plausible, the lambda value λ is measured using the pre-catalyst lambda sensor. With S3.1 denotes a step of the method in which, based on the recorded lambda value λ and using a predetermined weighting characteristic curve 7 (see Fig. 2), a map weighting factor K is determined, for which the following applies: 0^≤^K^≥^+1. The graph 7a of the weighting characteristic curve 7 results in the present case from the equation for ^^ < 0.9 for 0.9 ≤ ^^ < 1 for 1 ≤ ^^ ≤ 1.1. for ^^ > 1.1 Fig.2 shows further possible weighting characteristics 7. 7b denotes a graph of a weighting characteristic 7 which, instead of linear characteristic components, is formed from odd or non-linear characteristic components, for example according to a parabolic function, a logarithmic function, an exponential function, an inverse function, etc. In addition, weighting characteristics are conceivable which have both at least one linear characteristic component and at least one non-linear or odd characteristic component. In a step S3.2 of the method, for each operating mode involved in the overall operation of the internal combustion engine, a respective first oxygen supply partial value s is determined from the load-speed characteristic map for λ^=^1 assigned to the corresponding operating mode. aTherefore, if three operating modes are involved in the overall operation of the internal combustion engine, a first partial oxygen supply value s is determined from three load-speed maps for λ^=^1 a determined, a total of three first oxygen supply partial values ​​s a . The respective first oxygen supply partial value s a is then calculated in step S3.2 with the correction factor K, resulting in a first map-weighted oxygen supply partial value Sa: ^^ ^^ = ^^ ^^ ⋅ ^^ If the lambda value λ detected in step S2 is greater than 1, in a step S3.3.1 a second oxygen supply partial value s is determined from the characteristic map for λ^>^1 specified for the detected operating mode b If, however, the lambda value λ detected in step S2 is less than 1, a step S3.3.2 is carried out instead of step S3.3.1, in which the second oxygen supply partial value s bis determined from the characteristic map specified for the recorded operating mode for λ^<^1. In a step S3.4, the second oxygen supply partial value s b multiplied by the map weighting factor K, resulting in a second map-weighted oxygen supply partial value S b results: ^^ ^^ = ^^ ^^ ⋅ (1 − ^^) If the recorded lambda value is exactly λ^=^1, the map weighting factor K^=^1, whereby the second oxygen supply partial value s b ^= 0. In such a case, the first oxygen supply partial value s a weighted with 1 or 100^% and the second oxygen supply partial value s bwith 0 or 0^%. In the event that a lambda value λ is detected in step S2 that lies outside the lambda value ranges stored in the load-speed maps, an extrapolation factor E is further determined in the method. If such a lambda value λ is detected in step S2 that is not covered by the lambda value ranges of the load-speed maps, an oxygen supply partial value s determined from the corresponding map is a , s b , which corresponds to the nearest lambda value (λ) stored in the map, is multiplied by the extrapolation factor and used for the further process. The use of the extrapolation factor E is indicated in Fig. 3c by the reference symbol 4. The map-weighted oxygen supply partial values ​​S a , S b are converted in a step S4 of the method to an actual oxygen supply value SZ istAn example of such a map weighting process, in which the second oxygen supply value s b from the characteristic map for λ^>^1, is shown in Fig. 3a. The steps of the method described up to this point are carried out simultaneously and separately for each of the operating modes involved in the overall operation. Then, for example, in the respective step S4, the actual oxygen supply value SZist belonging to the corresponding operating mode is multiplied by the associated percentage operating mode shares B1, B2, ..., Bn, thereby generating operating mode share-weighted actual oxygen supply values ​​SZist B1, SZist B2, ..., SZist Bn, which are incorporated into a total actual oxygen supply value SZist tot in a step S5: 22-3450 18 for the first operating mode: ^^ ^^^^ ^^ ^^ ^^1= ^^1⋅ ^^ ^^ ^^ ^^ ^^ , for the second operating mode: ^^ ^^^^ ^^ ^^ ^^2= ​​^^2⋅ ^^ ^^ ^^ ^^ ^^ , for each additional operating mode: ^^ ^^^^ ^^ ^^ ^^ ^^= ^^ ^^ ⋅ ^^ ^^ ^^ ^^ ^^. In the exemplary embodiment of the method described here, an overrun combustion chamber number Z is also determined, which characterizes the number of combustion chambers of the internal combustion engine that are operated in an unfired (ignition-free) overrun mode. If exactly four combustion chambers or cylinders of the internal combustion engine are operated in overrun mode, the overrun combustion chamber number Z^=^4. In addition, a combustion chamber-specific overrun oxygen supply value SZ is determined. Zwhich characterizes the amount of oxygen supplied to the catalyst from exactly one unfired combustion chamber of the internal combustion engine. The overrun oxygen supply value SZZ is determined here based on an air mass flow that is channeled through the corresponding unfired combustion chamber during overrun. If the method in this example further detects that the overrun combustion chamber number Z is smaller than the total number of combustion chambers ZVKM, a combustion chamber correction factor ZK is calculated: If the internal combustion engine used here as an example has a total of six combustion chambers / cylinders, the combustion chamber correction factor ZK = 0.6̅. The combustion chamber correction factor ZK and the actual oxygen supply value SZist are then multiplied together, resulting in an overrun-corrected actual oxygen supply value SZ ist Z korr results: ^^ ^^^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^= ^^ ^^ ^^ ^^ ^^⋅ ^^ ^^ In this example, the overrun-mode-corrected actual oxygen supply value SZist Z corr is two-thirds of the actual oxygen supply value SZist resulting from the fully fired operation of the internal combustion engine. The combustion chamber-specific overrun-mode oxygen supply value SZZ and the overrun-mode combustion chamber number Z are multiplied together, resulting in an actual combustion chamber oxygen supply value SZZ ist: ^^ ^^^^ ^^ ^^ ^^= ^^ ^^ ^^ ⋅ ^^ 22-3450 19 After this, in step S5, the overrun-mode corrected actual oxygen supply value SZ ist Z korr and the actual combustion chamber oxygen supply value SZ Z ist to the total actual oxygen supply value SZ ist ges added: If, however, it is detected that the overrun combustion chamber number Z and the total number ZVKM of the combustion chambers are the same, the overrun oxygen supply value SZZ and the overrun combustion chamber number Z are multiplied with each other, resulting in the total actual oxygen supply value SZist ges in step S5: ^^ ^^^^ ^^ ^^ ^^ ^^ ^^= ^^ ^^ ^^ ⋅ ^^ The proportion of the process in which the overrun cut-off is included in the determination of the oxygen demand value m O2 Bedarf is shown in Fig.3d in the area of ​​reference number 5. In a step S6, an actual oxygen quantity value m O2 ist which characterizes the actual oxygen quantity, here the actual oxygen mass, currently stored in the catalyst. For this purpose, the total actual oxygen supply value SZ ist ges for example, added to an initial oxygen quantity value m0 of the catalyst. In this case, it is intended that before the initial determination of the oxygen demand value m O2 Bedarf, especially before determining the oxygen quantity value m for the first time O2 ist , a lambda deflection is detected by means of a post-catalyst lambda probe (which can also be referred to as a trim probe) located downstream of the catalytic converter in the exhaust system, which characterizes the presence of a defined amount of oxygen in the catalytic converter. In step S6, the actual oxygen quantity value m O2 ist of the catalyst by determining the total actual oxygen supply value SZ ist gesand an oxygen quantity output value m0 characterizing the defined oxygen quantity are added. In a step S7, the oxygen demand value m is calculated based on the total actual oxygen supply value SZist ges, the actual oxygen quantity value mO2 ist, and a target oxygen quantity value mO2 soll, which characterizes the target oxygen quantity, for example, a target oxygen mass, in the catalyst at which the catalyst operates at the best possible conversion rate. O2 Bedarf This characterizes an oxygen supply which – depending on the sign of the oxygen demand value m O2 Bedarf– is to be supplied to or removed from the catalyst in order to set the target amount of oxygen in the catalyst at which the catalyst operates at the best possible conversion rate. In this example, it is also provided that an uptake correction factor M is determined based on the oxygen uptake capacity of the catalyst. The oxygen uptake capacity of the catalyst is determined based on an exhaust gas mass flow and the actual amount of oxygen in the catalyst using an uptake capacity map specially developed for the process. The following applies to the uptake correction factor M: – if the catalyst is fully capable of absorbing oxygen: M^≥^1, – if the catalyst is partially capable of absorbing oxygen: 0^<^M^≤^1, – if the catalyst is not capable of absorbing oxygen at all: M^=^0.The uptake correction factor M is multiplied by the total actual oxygen supply value SZist ges, so that the total actual oxygen supply value SZist ges is scaled according to the current oxygen uptake capacity of the catalyst. In the area of ​​reference number 6 in Fig. 3c, a possible control engineering implementation for determining the uptake correction factor M is shown. In a step S8, the oxygen requirement value mO2 requirement is provided, here sent to another control unit, in this case the engine control unit of the internal combustion engine. Up to this point, steps of the method for a recording time step have been described as examples in order to arrive at the oxygen requirement value mO2 requirement for that recording time period. Steps S1 to S8 - in particular together with one or more of the described sub- orSecondary steps are repeated at least once in the present case, particularly as long as the catalytic converter device is operated in an activated operating state. In the respective step S5, the total actual oxygen supply value SZist ges is determined recursively by combining the actual oxygen supply values ​​SZist of the detection time periods over a total duration of the detection time periods to determine the total actual oxygen supply value SZ. ist ges integrated or added together. In addition, in step S6, the actual oxygen quantity value mO2 is recursively developed by adding the total actual oxygen supply value SZ to an actual oxygen quantity value mO2 of a previous run through the method steps. ist ges of the current run. The oxygen demand value m O2 Bedarfis consequently continuously adjusted and made available throughout the operation of the catalytic converter. If steps of the method are repeated, it is provided in particular that the oxygen quantity output value m0 is only recorded by means of a single, initial deflection of the post-catalyst lambda sensor. It can further be provided that the initial deflection of the post-catalyst lambda sensor is used as a start signal for the method, with the method not being executed until the initial deflection of the post-catalyst lambda sensor is recorded. To describe an alternative embodiment of the method, only differences to the possible embodiment of the method described up to this point will be discussed below. Unless explicitly stated otherwise, the description of the possible embodiment described up to this point applies to the alternative embodiment. In step S3.1, a map weighting factor (K) is determined based on the recorded lambda value λ using the specified weighting characteristic curve 7, for which the following applies: −1^≤^K^≥^+1. The graph 7c of the weighting characteristic curve 7 is then obtained, for example, from the equation: −1 for ^^ < 0.9 ^^ = { ( ^^ − 1) ⋅ 10 for 0.9 ≤ ^^ ≤ 1.1 1 for ^^ > 1.1 In step S3.2, the determined first oxygen supply partial value s. a multiplied by a difference whose minuend is 1 and whose subtrahend is the value of the map weighting factor K, from which the first map-weighted oxygen supply partial value S a results. ^^ ^^ = ^^ ^^ ⋅ (1 − | ^^|) In step S3.4, the second oxygen supply partial value sb is multiplied by the value of the map weighting factor K, resulting in the second map-weighted oxygen supply partial value Sb. ^^ ^^ = ^^ ^^ ⋅ | ^^ |Steps S1, S2, S3.3, S3.3.1, S3.3.2, and S4–S8, as well as any secondary or sub-steps, are carried out in the alternative embodiment as described above. The method for operating the catalytic converter, the catalytic converter, the internal combustion engine, the control method, and the motor vehicle demonstrate a respective possibility for improving the efficiency of a catalytic converter. The amount of exhaust gas exiting the catalytic converter untreated or with only minimal treatment is significantly reduced compared to the prior art.

[0002] List of reference symbols B1, B2, …, B n Operating mode share E Extrapolation factor K Map weighting factor M Absorption correction factor m0Oxygen quantity output value m O2 Bedarf Oxygen demand value m O2 istActual oxygen quantity value mO2 soll Target oxygen quantity value Sa First map-weighted partial oxygen supply value sa First oxygen supply partial value (unweighted) Sb Second map-weighted partial oxygen supply value sb Second oxygen supply partial value (unweighted) SZist B1, …, SZist Bn Operating mode-weighted actual oxygen supply value SZist ges Total actual oxygen supply value SZist Z korr Overrun-corrected actual oxygen supply value SZist Actual oxygen supply value SZZ ist Actual combustion chamber oxygen supply value SZZ Combustion chamber-specific overrun-mode oxygen supply value t0 Load change time Z Overrun combustion chamber number ZK Combustion chamber correction factor ZVKM Total number of combustion chambers in the internal combustion engine Δt0–1 Gas run time Δt1–2 Sensor reaction time λ Recorded lambda value 1, 2, 3 Operating mode 4 Use of the extrapolation factor 5 Determination of the overrun cut-off 6 Determination of the intake correction factor 7 Weighting characteristic 7a, 7b, 7c Weighting characteristic graph

Claims

24 claims 1. Method for operating a catalyst device for an internal combustion engine having a catalyst, wherein in a detection time period S1 an active operating mode of the internal combustion engine is detected, S2 a lambda value (λ) is detected, and based thereon S3.1 a characteristic map weighting factor (K) is determined, S3.2 from a characteristic map predetermined for the detected operating mode for λ^=^1 a first oxygen supply partial value (s a ) and calculated with the map weighting factor (K), from which a first map-weighted oxygen supply partial value (S a), S3.3 a second oxygen supply partial value (sb) is determined, namely, S3.3.1 if the lambda value (λ) is greater than 1, from a characteristic map specified for the recorded operating mode for λ^>^1, or, S3.3.2 if the lambda value (λ) is less than 1, from a characteristic map specified for the recorded operating mode for λ^<^1, S3.4 the second oxygen supply partial value (sb) is offset against the characteristic map weighting factor (K), resulting in a second characteristic map-weighted oxygen supply partial value (Sb), S4 the characteristic map-weighted oxygen supply partial values ​​(Sa, Sb) are added to an actual oxygen supply value (SZist) characterizing an actual oxygen supply of the catalyst, S5 the actual oxygen supply value (SZist) total actual oxygen supply value (SZist ges) is recorded, S6 an actual oxygen quantity value (mO2 ist) is recorded, which characterizes an actual oxygen quantity that is currently stored in the catalyst,S7 Based on the total actual oxygen supply value (SZist ges), the actual oxygen quantity value (mO2 ist) and a target oxygen quantity value (mO2 soll), which characterizes a target oxygen quantity in the catalyst at which the catalyst operates at the best possible conversion rate, an oxygen demand value (mO2 bedarf) is determined, which characterizes an oxygen supply that is to be supplied to the catalyst in order to adjust the target oxygen quantity in the catalyst, S8 the oxygen demand value (mO2 bedarf) of the recording time period is provided. 22-3450 25 2. Method according to claim 1, characterized in that - in step S3.1 the characteristic map weighting factor (K) is determined, which is at least 0 and at most +1, - in step S3.2 the determined first oxygen supply partial value (s a ) is multiplied by the map weighting factor (K), from which the first map-weighted oxygen supply partial value (S a), and – in step S3.4, the second oxygen supply partial value (s b ) is multiplied by a difference whose minuend is 1 and whose subtrahend is the characteristic map weighting factor (K), from which the second characteristic map-weighted oxygen supply partial value (Sb) results.

3. Method according to claim 2, characterized in that the characteristic map weighting factor (K) is determined based on a predetermined weighting characteristic curve (7), wherein at least one characteristic curve component of the weighting characteristic curve (7) is formed according to the following equation: for ^^ < 0.9 for 0.9 ≤ ^^ < 1 for 1 ≤ ^^ ≤ 1.1 for ^^ > 1.1 4. Method according to claim 1, characterized in that - in step S3.1 the characteristic map weighting factor (K) is determined, which is at least −1 and at most +1, - in step S3.2 the determined first oxygen supply partial value (s a) is multiplied by a difference whose minuend is 1 and whose subtrahend is the value of the map weighting factor (K), from which the first map-weighted oxygen supply partial value (S a ), and - in step S3.4 the second oxygen supply partial value (sb) is multiplied by the amount of the map weighting factor (K), from which the second map-weighted oxygen supply partial value (Sb) results. 22-3450 26 5. Method according to claim 4, characterized in that the characteristic map weighting factor (K) is determined based on a predetermined weighting characteristic (7), wherein at least one characteristic curve component of the weighting characteristic (7) is formed according to the following equation: −1 for ^^ < 0.9 ^^ = { ( ^^ − 1) ⋅ 10 for 0.9 ≤ ^^ ≤ 1.1 1 for ^^ > 1.1 6. Method according to one of the preceding claims, characterized in that the steps S1-S8 are repeated for a further recording time period, wherein in the respective step S5 the actual oxygen supply values ​​(SZist) are integrated over a total duration of the recording time periods to the total actual oxygen supply value (SZist ges) and in the respective step S6 a current actual oxygen quantity value mO2 ist is recorded by the Actual oxygen levels (mO2) are added up over the entire duration. 7.Method according to claim 5, characterized in that before the oxygen demand value (mO2 demand) is determined for the first time, a lambda deflection is detected by means of a post-catalyst lambda probe arranged downstream of the catalyst in the exhaust system, which lambda deflection characterizes the presence of a defined amount of oxygen in the catalyst, and the actual oxygen quantity value (m. O2 ist ) of the catalyst is recorded by calculating the total actual oxygen supply value (SZ ist ges ) and an oxygen quantity output value (m0), which characterizes the defined oxygen quantity, are added together. 22-3450 27 8. Method according to one of the preceding claims, characterized in that, a further active operating mode is detected, wherein the steps S2-S4 are carried out separately and in parallel for each of the detected active operating modes, wherein - it is detected which percentage operating mode share (B1, B2, ..., B n) the respective operating mode has on a current overall operation of the internal combustion engine, – the respective actual oxygen supply value (SZ ist ) with the corresponding percentage of the operating mode shares (B1, B2, …, B n ) is multiplied, and – in step S5 the total actual oxygen supply value (SZ ist ges ) is recorded by calculating the operating mode weighted actual oxygen supply values ​​(SZ ist B1 , SZ ist B2, ..., SZist Bn) are added.

9. Method according to one of the preceding claims, characterized in that, if a lambda value (λ) is detected in step S2 which lies outside the lambda value ranges stored in the characteristic maps, an extrapolation factor (E) is determined, and an oxygen supply partial value (sa, sb) determined from the corresponding characteristic map, which corresponds to a nearest of the lambda values ​​(λ) stored in the characteristic map, is multiplied by the extrapolation factor (E) before step S5. 10.Method according to one of the preceding claims, characterized in that based on an oxygen uptake capacity of the catalyst, an uptake correction factor (M) is determined which, if the catalyst - is fully capable of oxygen uptake, is at least 1 or greater, - is partially capable of oxygen uptake, is less than 1 and greater than 0, or - is not capable of oxygen uptake at all, is 0, wherein the uptake correction factor (M) is multiplied by the total actual oxygen supply value (SZist ges). 22-3450 28 11. Method according to one of the preceding claims, characterized in that an overrun combustion chamber number (Z) is recorded, which characterizes a number of combustion chambers of the internal combustion engine which are operated in an unfired overrun mode, and on the basis of an air mass flow channeled through an unfired combustion chamber in overrun mode, a combustion chamber-specific overrun oxygen supply value (SZZ ), and, – if the overrun combustion chamber number (Z) is less than a total number (Z VKM ) of the combustion chambers of the internal combustion engine, ‒ a combustion chamber correction factor (ZK) is calculated, which is a ratio of the overrun combustion chamber number (Z) to the total number (Z VKM) of the combustion chambers, ‒ the combustion chamber correction factor (ZK) and the actual oxygen supply value (SZist) are multiplied, resulting in an overrun-corrected actual oxygen supply value (SZist Z corr), ‒ the overrun-oxygen supply value (SZZ) and the overrun-combustion chamber number (Z) are multiplied, resulting in an actual combustion chamber oxygen supply value (SZZ ist), ‒ the overrun-corrected actual oxygen supply value (SZist Z corr) and the actual combustion chamber oxygen supply value (SZZ ist) are added to the total actual oxygen supply value (SZist ges), or – if the overrun-combustion chamber number (Z) and the total number (ZVKM) of combustion chambers are the same, the overrun-oxygen supply value (SZZ) and the overrun combustion chamber number (Z) are multiplied, resulting in the total actual oxygen supply value (SZist ges). 12.Catalyst device for an internal combustion engine, wherein the catalyst device is configured to carry out the method according to one of claims 1 to 11. 22-3450 29 13. An internal combustion engine to which the catalyst of a catalyst device designed according to claim 12 is connected on the exhaust side, wherein the internal combustion engine accepts the oxygen demand value determined by means of the method according to one of claims 1 to 11 as a control signal and is consequently controllable such that it provides an oxygen supply by means of which the target oxygen quantity is set in the catalyst.

14. A control method for controlling an internal combustion engine designed according to claim 13, wherein it is controlled such that it provides an oxygen supply by means of which the target oxygen quantity is set in the catalyst.

15. A motor vehicle with an internal combustion engine designed according to claim 14.

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