JP5311082B2 - Operation method of diesel engine equipped with exhaust gas purification device having nitrogen oxide storage catalyst - Google Patents

Abstract

The invention relates to a method wherein an air-fuel mixture having a lambda value is combusted in a combustion chamber of the diesel engine (1) and exhaust gas arising therefrom is fed into the nitrogen oxide storage catalytic converter (6). Starting from operation of the diesel engine (1) in a first operating mode, wherein the air-fuel mixture comprises a first lambda value greater than one, operation of the diesel engine (1) in a second operating mode is selected for regenerating the nitrogen oxide storage catalytic converter (6), wherein the air-fuel mixture comprises a second lambda value of less than one. Directly before selecting the second operating mode, a transition phase is inserted, in which the diesel engine (1) is operated in a third operating mode, wherein a third lambda value less than that of the first operating mode, and slightly greater than one, is set for the air-fuel mixture. According to the invention, operation of the diesel engine (1) takes place in the third operating mode and is controlled relative to the lambda value of the air-fuel mixture such that an exhaust gas lambda value is captured by means of a lambda sensor (9) disposed downstream of the nitrogen oxide storage catalytic converter (6) in the exhaust gas cleaning system (2), and said value is used as a control parameter for controlled adjustment of a prescribable target value for the third lambda value.

Description

  The present invention relates to a method for operating a diesel engine equipped with an exhaust gas purification device having a nitrogen oxide storage catalyst and a diesel engine equipped with a control device for carrying out this method.

  Patent Document 1 discloses an industry standard operation method for a diesel engine equipped with an exhaust gas purification device having a nitrogen oxide (NOx) storage catalyst. In this method, in connection with nitrate regeneration, an operation mode transition stage is inserted, starting from a lean mixture and immediately before a rich mixture with an excess air lambda value of 1 or less is set. In the stage, a lambda value slightly above 1 is set. This improves the generation of ammonia that is useful when reducing the nitrogen oxides stored in the nitrogen oxide storage catalyst in the next operation stage with a rich air-fuel mixture. The produced ammonia is used in the downstream SCR catalyst to further improve nitrogen oxide reduction. In order to efficiently achieve an excellent regeneration result, it is necessary to set a reliable and reproducible lambda value, particularly in a rich operation stage in which substantial regeneration of the nitrogen oxide storage catalyst is performed.

German Patent Application Publication No. 1034976A1 Specification

  An object of the present invention is to provide a method of operating a diesel engine equipped with an exhaust gas purifying device having a nitrogen oxide storage catalyst, and particularly when performing regeneration of the nitrogen oxide storage catalyst by this method. Lambda values can be set reliably and reproducibly. A further object of the present invention is to provide a diesel engine equipped with an exhaust gas purification device having a nitrogen oxide storage catalyst, and with this engine, the regeneration of the nitrogen oxide storage catalyst can be efficiently performed in a simple manner. can do.

  This problem is solved by a method having the features of claim 1 and a diesel engine having the features of claim 16.

  The method according to the invention operates by means of a diesel engine, in which the air-fuel mixture having a lambda value is at least partially burned in the combustion chamber or chambers of the diesel engine, and the exhaust gas generated therewith is oxidized by nitrogen. It is sent to the material storage catalyst. Starting from the operation of the diesel engine in a first operating mode in which the air-fuel mixture has a first lambda value greater than 1, a second air-fuel mixture is less than 1 for regeneration of the nitrogen oxide storage catalyst. Operation in the second operation mode having a lambda value is set for the diesel engine. Immediately before setting the second operation mode, an operation mode transition stage is inserted, in which the air-fuel mixture is adjusted to a third lambda value that is lower than the lambda value of the first operation mode and slightly above 1. The diesel engine is operated in the third operation mode. According to the present invention, in the third operation mode, the closed-loop mode operation of the feedback control of the diesel engine is performed with respect to the lambda value of the air-fuel mixture, and is arranged downstream of the nitrogen oxide storage catalyst in the exhaust gas purification device. The lambda sensor detects the lambda value of the exhaust gas, and this lambda value is used as an adjustment value for adjusting the target value that can be defined for the third lambda value.

  The target value of the third lambda value in the operation mode transition stage provided in accordance with the present invention is usually in the range of 1.01-1.10, preferably 1.02-1.06, particularly preferred. Is approximately 1.03 and is therefore relatively close to the second lambda value of approximately 0.95 set during actual playback. Thereby, in the operation mode transition stage, the engine operation value that determines the operation of the diesel engine is changed to a value that is required in the operation stage in the second operation mode of the diesel engine that is operated with a rich air-fuel ratio immediately after that. It is possible to adjust at least close. Thus, the operating mode transition stage implemented in accordance with the present invention works for stable adjustment of engine operating parameters required for rich engine operation, but here also results in weak lean engine operation.

  Therefore, it is possible to approach the rich engine operating conditions that are difficult to adjust in principle with a diesel engine in an advantageous manner. The next transition to the second operating mode can be easily performed since only a slight change in one or more engine operating values is required. Preferably, the operating mode transition phase with a lambda value slightly above 1 is only retained if necessary to set stable conditions. Usually, this time is in the second range, one digit below. Preferably, the operation mode is switched from the third operation mode to the second operation mode about 2 to 5 seconds after the diesel engine is operated.

  In particular, since the operation mode transition stage is weakly lean, in the third operation mode of the lambda adjustment engine operation prepared in accordance with the present invention, it is possible to set the engine operation particularly surely and accurately. In this case, since the lean air-fuel mixture is similarly set in the first operation mode, the lambda sensor disposed downstream of the nitrogen oxide storage catalyst used for lambda adjustment in the operation mode transition stage is provided. It is used to provide a measurement that very closely matches the lambda value of the air-fuel mixture combusting in the diesel engine. Since the first operation mode is usually set over a long time in a range of 10 seconds to several minutes, the effect of the nitrogen oxide storage catalyst that affects the lambda value of the exhaust gas is attenuated.

In the sense of the present invention, an exhaust gas purification element is understood as a nitrogen oxide storage catalyst, which element preferably has a catalyst layer with a nitrogen oxide storage action on an internal carrier implemented in a honeycomb structure. ing. The corresponding storage component can be an alkali or alkaline earth compound such as barium carbonate. This component produces individual barium nitrate or barium sulfate to remove nitrogen oxides (NO _x ) and sulfur oxides (SO _x ) from oxidizable exhaust gases having lambda values greater than one. Due to the depletion of the materials associated with these, it may be necessary to regenerate the nitrogen oxide storage catalyst, which removes the stored NO _x or SO _{x and} regenerates the storage power. Regeneration occurs by supplying reducible exhaust gas over a period of time. In this case, the nitrate ester or sulfate ester can be decomposed while releasing the corresponding oxide. NO _x released again is a catalytic layered component on the nitrogen oxide storage catalyst by the reducing agents (H ₂ , CO and HC) contained in the exhaust gas, harmless nitrogen (N ₂ ) and ammonia Reduced to (NH ₃ ).

  The lambda value here means a stoichiometric ratio composed of the oxygen content and the oxygen or reducing component content in the air-fuel mixture or exhaust gas sent to the engine, as in the prior art. If the lambda value is greater than 1, there is a lean mixture or exhaust gas containing excess oxygen, and if the lambda value is less than 1, there is a rich mixture or exhaust gas containing excess reducing agent. To do.

  Usually, air and fuel are sent separately to the fuel chamber of a multi-cylinder diesel engine, preferably operating in a four-stroke manner, and burned in the combustion chamber while being subjected to mechanical work. Combustion is more or less complete depending on the combustion method. In order to remove harmful substances from the exhaust gas, this exhaust gas purification device further has components having a filtering action and / or catalytic action in addition to the nitrogen oxide storage catalyst. Further, the exhaust gas purification device has a sensor for detecting exhaust gas characteristic parameters such as temperature and composition.

  The lambda value of the combustion exhaust gas is equal to the lambda value of the air-fuel mixture immediately after ejection from one combustion chamber or a plurality of combustion chambers. However, lambda values may vary due to the action of the exhaust gas purification component, in particular due to the conversion, occlusion and / or liberation of exhaust gas components. Further, the lambda value may be fluctuated by supplying air or fuel to the exhaust gas from a source outside the engine. For clarity, the exhaust gas lambda value is described in detail below. The lambda value of the air-fuel mixture sent to the combustion chamber of the engine is also referred to below as the engine lambda value where it needs to be clearly indicated. Hereinafter, although not necessarily limited, in the case of the method according to the present invention, the variation of the lambda value of the exhaust gas supplied from the nitrogen oxide storage catalyst is caused only by the variation of the engine lambda value or almost the variation of the engine lambda value. It is assumed that it is caused only by.

Nitrogen oxide storage catalysts typically have an occlusion action with respect to oxygen and / or reducing agents, and in particular from engine lambda values greater than 1 to engine lambda values less than 1 (or vice versa). When switching to, there is temporarily an exhaust gas lambda value different from the engine lambda value downstream of the nitrogen oxide storage catalyst. In order to detect them, so-called lambda sensors are provided, which can be formed in the general form for those skilled in the art, for example as a binary or continuous lambda sensor or as a lambda-sensitive NO _x sensor.

  In accordance with the invention, a closed control circuit is provided, in which the exhaust gas lambda value is reduced downstream of the nitrogen oxide storage catalyst, in particular during operation of the diesel engine in the third operating mode. Detected continuously or frequently by a lambda sensor and returned as an adjustment value. Within the control circuit, a comparison is made with a settable target value so that the regulator of the control circuit has at least approximately zero error between the lambda value detected by the lambda sensor and the target value of the third lambda value. Next, adjust the engine lambda value. This regulator can be formed by embodiments common to those skilled in the art, such as a PI or PID regulator. This regulator can be implemented in hardware and / or software.

  In the embodiment of the present method, the operation in the open loop mode of the feedforward control of the diesel engine is performed with respect to the lambda value of the air-fuel ratio in the second operation mode. Thereby, in the second operation mode, while the nitrogen oxide storage catalyst is actually regenerated, the reducible components contained in the exhaust gas are used for the reduction of NOx or SOx, Removed. For this reason, an exhaust gas lambda value is detected by a lambda sensor arranged downstream, and this value does not coincide with the engine lambda value as long as at least the reducible exhaust gas component is consumed significantly. As a result of this, the exhaust gas lambda value is almost the stoichiometric value of 1 unless the adjusted engine lambda value is low but the removal of the stored nitrogen oxides is not yet complete. Stay on. In this case, the exhaust gas lambda value measured downstream of the nitrogen oxide storage catalyst is not used as an adjustment value for adjusting the engine lambda value.

  In another embodiment of the method, a target value is provided for the second lambda value, and the engine operating value as an adjustment value that affects the lambda value of the mixture in the second and third operating modes. Are controlled in advance, that is, pilot-controlled, and the second and third lambda values are controlled by the pilot control so as to at least substantially reach the set target values, respectively.

  Preferably, in the second and third operating modes, a number of engine operating values are adjusted by pilot control, and preferably the input values are held callable in memory. In this case, the engine operation value set by the pilot control does not necessarily have to be effective for the lambda control performed in the third operation mode as an adjustment value in terms of control technology.

  Preferably, the recalled and set input values are assigned to the respective operating points of the diesel engine in terms of load and speed. In particular, in the third operation mode with a weak lean air-fuel ratio, the main engine operation value that determines the combustion of fuel in the combustion chamber is already set to the same value as that required for the rich operation in the second operation mode. Be prepared to set up. With this method, this combustion method is already set from the operating mode transition stage in the next second operating mode, depending on the need for at least partial combustion of the rich mixture. Therefore, since the transition to the second operation mode requires only a slight change, a reliable and accurate transition is performed.

  In another embodiment of the method, the pilot control is designed as a learning-type pilot control, and a correction value that can be changed adaptively and that affects the adjustment value is provided. This correction value may be formed as a correction value that acts multiplicatively or additively on the adjustment value for adjusting the second and / or third lambda values. This correction value is therefore formed as a learning value that can be changed adaptively and is adapted to allow the pilot control to adjust the control value variation as needed based on the confirmed control value variation. . Adaptively implemented pilot control, among other things, can effectively compensate for transient currents that vary slightly over time, but it minimizes the control intervention that regulates transient currents, so This is because it can be performed very quickly and can be performed with slight excessive vibration.

  If necessary, the newly learned correction value is inherited from the lambda control mode in the third operation mode at the operation mode transition stage to the engine operation in the second operation mode by pure pilot control immediately after that. . With learning-type pilot control, a relatively small lambda variation from about 1.03 to 0.95 can be implemented very precisely. On the other hand, if the operation mode transition stage implemented in accordance with the present invention is omitted and the normal transition from the relatively high first lambda value to the rich second lambda value is performed directly, there is a great obstacle. It will be an easy and inaccurate transition.

  In another embodiment of the method, in the second and third operating modes, pilot control of the total injection quantity of fuel injected into the combustion chamber of the diesel engine is performed during the operating cycle, and the air mass sensor device Depending on the sensed air flow supplied to the diesel engine to at least partially burn the mixture, the second and third lambda values at least approximately reach their respective target values. To be prepared. In this case, it is particularly preferred that, in another embodiment of the method according to the invention, the air flow detected by the air mass sensor device is used as an adjustment value for adjusting a settable air flow target value. It is. In order to adjust the air flow rate, an independent control circuit is preferably provided. By this method, adjustment of the air flow rate and the total injection amount as a value for determining the air-fuel ratio is separated in terms of control technology. The air mass sensor device normally supplies actual air flow measurements with high accuracy, so that the engine and lambda values can be adjusted very precisely as well by using the total injection amount adjusted accordingly. Can do.

  In another embodiment of the method, the total injection quantity includes a main injection quantity injected in the main injection and a post injection quantity injected in the post injection following the main injection. The main injection amount is preferably injected into the combustion chamber at a crankshaft angle of about 10 degrees before top dead center to about 10 degrees after top dead center, and the post injection amount is preferably about 15 degrees after top dead center It is injected into the combustion chamber during the operating cycle at a crankshaft angle of about 45 degrees. This post-injection enables the enhancement or enrichment of the air-fuel mixture in an effective manner with little or no effect on the diesel engine output or torque output. Preferably, a pre-injection that takes place before the main injection is provided in the compression cycle in order to improve the combustion process. Particularly preferred is that the two pre-injections are carried out at short intervals. The relevant pre-injection quantity is advantageously injected at a crankshaft angle between 25 and 15 degrees before top dead center.

  Particularly advantageous in connection with dividing the total injection quantity into at least a main injection and a post-injection, in another embodiment of the method, the post-injection quantity is the second and / or third It is used as an adjustment value for adjusting the target value of the lambda value. Apart from the increase in the post-injection quantity, it is advantageous for the transition from the third operating mode to the second operating mode to continue without changing all or at least most other engine operating values. Therefore, preferably, the enrichment of the air-fuel mixture in the transition from the third lambda value to the second lambda value is performed only by increasing the post-injection amount.

  In another embodiment of the method, in the third mode of operation, the error between the exhaust gas lambda value resulting from the pilot control and the target value of the third lambda value is investigated and, if necessary, this error. The correction value that can be changed adaptively is changed so that is at least almost negligible. Therefore, learning or adaptation of the correction value is performed during the operation mode transition stage when the diesel engine is operated in the third operation mode, and the newly learned correction value is written in a readable memory, It is read again when the operation mode 3 is set. It is preferable that predetermined permission conditions are provided for performing the adaptation, for example, the maximum load that can be set and / or the maximum fluctuation value of the maximum rotational speed is exceeded and there is no coasting operation. It is. If this permission condition does not exist, the correction value adaptation or learning is not performed or interrupted. In this case, the third lambda value is not adjusted, but the lambda value is adjusted by the pilot control based on the correction value that was valid before. It is preferable that the newly learned correction value is not taken in if the error from the correction value that has been valid is below the minimum range that can be set or exceeds the maximum range that can be set. It is. This measure avoids too frequent learning or learning mistakes in the correction values.

  In another embodiment of the method, an engine operating characteristic map is provided, which has a characteristic map range with configurable values, each of which is assigned a correction value. Preferably, the engine operating characteristic map is a load-rotation speed characteristic map. Ensuring that the nitrogen oxide storage catalyst is regenerated by setting the lambda value accurately in at least most portions of the engine operating characteristic map, among other things, in another embodiment of the invention, the second and / or When the pilot control for adjusting the third lambda value is engine operation in the specified characteristic map range, the correction value assigned to this characteristic map range is set in relation to the regeneration of the nitrogen oxide storage catalyst. By using it, it becomes possible. Preferably, the engine operating characteristic map is divided into 10 to 20 equally large characteristic map ranges. However, there may be a finer or larger characteristic map segmentation method. In particular, in the case of rough division, it is advantageous to perform interpolation between adjacent correction values and use the interpolation values.

  In another embodiment of the present invention, in the second operation mode, at least one of the engine operation value, the exhaust gas recirculation rate, and the intake throttle rate is adjusted in the same manner as the third operation mode set immediately before the second operation mode. Is done. This method enables a particularly reliable and smooth transition from the third operating mode to the second operating mode. Preferably, further engine operating parameters such as, for example, main injection and / or pre-injection injection times and injection quantities are taken over unchanged.

  In another embodiment of the present invention, in performing the nitrate ester regeneration for removing the stored nitrogen oxide from the nitrogen oxide storage catalyst in the second operation mode, the downstream of the nitrogen oxide storage catalyst is performed. The exhaust gas lambda value detected by the lambda sensor located in the engine is monitored to see if it is below a settable threshold. 1 is returned to the operation mode. Therefore, the lambda sensor arranged downstream of the nitrogen oxide storage catalyst serves to detect the end of nitrate regeneration, and in this case, the standard threshold value is in the range of 1.00 to 0.98. It is advantageous to choose a lambda value. This can avoid or at least minimize the inadequate cut-off of exhaust gas components such as carbon monoxide or hydrocarbons with sufficient certainty.

  In another embodiment of the present invention, in the second operation mode, when performing the sulfate ester regeneration for removing the stored sulfur oxide from the nitrogen oxide storage catalyst, the downstream of the nitrogen oxide storage catalyst. The exhaust gas lambda value sensed by a lambda sensor located at is monitored to see if it falls below a settable threshold, and at least approximately maintains a second lambda value after falling below the settable threshold Regarding the lambda value of the air-fuel mixture, the operation mode of the diesel engine is switched from the open loop control mode to the closed loop control mode.

  Sulfur oxides stored in the nitrogen oxide storage catalyst are usually bound much more strongly than the stored nitrogen oxides, so that in the case of sulfate ester regeneration, 550 ° C or higher compared to nitrate ester regeneration. Both high temperature and longer duration rich combustion modes are required. Thus, in the case of sulfate ester regeneration, the second mode of operation is preferably maintained unchanged from 10 seconds to 30 seconds. However, even if only a part of this time has elapsed, the consumption of reducible exhaust gas components in the nitrogen oxide storage catalyst is extremely low, so the exhaust gas lambda value detected by the lambda sensor is At least approximately the same as the engine lambda value. When approaching the target possible value, the lambda control mode of the diesel engine can be implemented again using the measurements provided by the lambda sensor. This improves the setting accuracy of rich exhaust gas and lambda values necessary for efficient sulfate ester regeneration.

  The problem based on the present invention is also solved by a diesel engine having an exhaust gas purification device having a nitrogen oxide storage catalyst and a control device for carrying out the method according to the present invention, and storing the nitrogen oxide storage in the exhaust gas purification device. The lambda sensor located downstream of the catalyst is the only lambda sensor provided in the exhaust system to set the lambda value of the mixture that burns at least partially within the combustion chamber of the diesel engine. Since the lambda value can be adjusted only by a lambda sensor arranged downstream of the nitrogen oxide storage catalyst in the exhaust gas purification device, it is particularly arranged upstream of the nitrogen oxide storage catalyst in the exhaust gas purification device. Another lambda sensor is not required. Thus, considerable cost savings can be achieved.

  In the embodiment of the present invention, a particulate collection filter is disposed between the nitrogen oxide storage catalyst and the lambda sensor in the exhaust gas purification device. The lambda sensor is located downstream of the particulate collection filter, which additionally enables control or monitoring of particulate collection filter regeneration by soot combustion. Furthermore, the risk of soot sticking to the lambda sensor is prevented, thereby improving the reliability and accuracy of the lambda value measurement.

  Advantageous embodiments of the invention are illustrated in the drawings and are described below. In this case, the features shown here and those described below can be applied not only to the combinations of the features shown respectively, but also to other combinations or alone without departing from the scope of the present invention.

It is a mimetic diagram showing an embodiment of a diesel engine and an exhaust gas purification device for carrying out a method based on the present invention. In the context of the implementation of nitrate ester regeneration, the time course of the lambda value λ _M of the air-fuel mixture combusting in the diesel engine and the time course of the lambda value λ _Am in the exhaust gas measured downstream of the nitrogen oxide storage catalyst is there. In the context of the sulfate ester regeneration implementation, the time course of the lambda value λ _M of the air-fuel mixture combusting in the diesel engine and the time course of the lambda value λ _Am in the exhaust gas measured downstream of the nitrogen oxide storage catalyst is there.

  FIG. 1 is a schematic diagram showing an advantageous embodiment of an internal combustion engine 1 and an exhaust gas purification device 2 for a vehicle (not shown) for carrying out the method according to the invention. This internal combustion engine 1 is preferably implemented as a direct injection, lean burnable, in particular air compression internal combustion engine according to the reciprocating principle, hereinafter referred to simply as a diesel engine. The fuel injection system not shown is preferably a so-called common rail system with adjustable rail pressure or fuel injection pressure, or in the form of a pump nozzle or pump line nozzle injection system. It has been implemented.

  Each cylinder of an internal combustion engine is assigned a combustion chamber with one or two inlet and outlet valves, a glow plug and a fuel injector, and one or more inlet ducts for combustion air. Are not shown in detail. In this case, the fuel injector can perform multipoint injection.

The diesel engine 1 receives combustion air via an air supply line 3 in which an air mass sensor (not shown) is arranged. This air mass sensor is preferably formed as a so-called hot film air mass sensor or hot wire air mass sensor. Variations in the air density are detected by this sensor and can be corrected when adjusting the air flow rate. Similarly, the flow rate of air supplied to the diesel engine 1 can be reduced to an adjustable amount by an adjustable throttle element (not shown). The combustion air is compressed by the exhaust turbocharger 15 and sent to the intercooler 16 for cooling. This exhaust turbocharger is preferably implemented as a so-called VTG turbocharger or a Westgate turbocharger with an adjustable charge pressure. Exhaust gas is generated in the combustion chamber of the cylinder of the diesel engine 1 and is discharged through the exhaust gas line 4. In this case, the exhaust gas is mixed with the combustion air by the exhaust gas feedback line 13, thereby being sent back to the diesel engine 1. The ratio of the returned exhaust gas (EGR rate) can be adjusted by the EGR valve 14. Preferably, the exhaust gas returned to the diesel engine 1 is cooled by an EGR radiator (not shown), and an adjustable bypass can be provided for the EGR radiator as needed. Thereby, the cooled exhaust gas or the hot exhaust gas can be selectively mixed with the combustion air. The exhaust gas that has not been fed back is sent to the exhaust gas purification device 2 via the exhaust turbocharger 15. According to the described embodiment, various values of important engine operating parameters such as air flow, injection time of multi-point fuel injection, injection pressure and injection time, EGR rate, charge air pressure and various combustion methods, Can be prepared as needed. In particular, the diesel engine 1 can be operated by an air-fuel mixture in which the lambda value indicating the excess air ratio (hereinafter referred to as the engine / lambda value λ _M ) changes. An engine lambda value λ _M greater than 1 corresponds to operation of a lean mixture or lean diesel engine 1, and an engine lambda value λ _M of less than 1 is operation of a rich mixture or rich diesel engine 1. It corresponds to. Lean engine operation produces lean exhaust gases that are particularly rich in oxidizing components such as oxygen. In rich engine operation, there are many reducing components such as carbon monoxide, hydrogen, and hydrocarbons. Rich exhaust gas is produced. The composition of the exhaust gas is characterized below by the exhaust gas lambda value λ _A corresponding to this definition.

A preferred embodiment of the exhaust gas purification device 2 assigned to the diesel engine 1 is, in order, in the direction in which the exhaust gas flows, the oxidation catalyst 5, the nitrogen oxide storage catalyst 6, the diesel particulate filter 7 and the SCR. It has a catalyst 8. As the particulate collection filter 7, a so-called wall flow type filter of SiC base, cordierite base or aluminum base is preferably used. However, the particulate collection filter 7 can also be formed as a sintered alloy filter or as a filter unit having an open filter structure. The SCR catalyst 8 arranged downstream of the nitrogen oxide storage catalyst 6 has a characteristic that it can store NH ₃ under the reduction condition, and is supplied with the NH ₃ stored or in some cases under the oxidation condition. NH ₃ can be utilized as a reactant in a selective catalytic reduction reaction in the production of nitrogen to chemically reduce NO _x .

The latter property is used in particular to render NO _x sent to the SCR catalyst 8 harmless. In the arrangement according to FIG. 1, for example, during the lean combustion mode of the diesel engine 1, by NO _x slip increases by a decrease of the NO _x storage capacity of the nitrogen oxide storage catalyst 6 in _the NO _x storage elapsed, SCR catalyst 8 Receive NO _x . The SCR catalyst 8 is preferably formed as a V ₂ O ₅ —WO ₃ based bulk catalyst or as a noble metal containing catalyst layer. Particularly preferred is the practice as a supported catalyst with a zeolite coating comprising copper or iron. The catalysts 5, 7, 8 are implemented as a honeycomb body monolith through which a catalyst layer duct passes, and the supplied exhaust gas can flow through this duct.

  A fuel addition unit can be provided on the input side of the oxidation catalyst 5, and for example, fuel can be sent to the exhaust gas by this unit. Thus, the exhaust gas can be appropriately heated by the exothermic oxidation reaction of the fuel sent to the exhaust gas as necessary. In the presence of this fuel addition unit, this unit mainly operates in connection with the active regeneration of the particulate collection filter 7 by burning soot or heats the exhaust gas purification components connected downstream. Drive for. However, it is advantageous to omit this fuel addition unit and to mix an oxidizable component into the exhaust gas by driving the motor in a mode using a rich air-fuel mixture. The following assumes this application.

The exhaust gas aftertreatment device 2 is provided with various temperature sensors and exhaust gas sensors for detecting the exhaust gas, the temperature of the components, and the concentration of important exhaust gas components. For example, in FIG. 1, in the exhaust gas purification device 2, temperature sensors 10 and 11 are disposed on the input side of the nitrogen oxide storage catalyst 6 and the output side of the particulate collection filter 7, respectively. On the output side of the SCR catalyst 8, a gas sensor 12 that is sensitive to NO _x and / or NH ₃ is provided. In order to detect adhesion of soot and / or ash to the particulate collection filter 7, it is advantageous to further provide a pressure sensor or a differential pressure sensor on the input side and the output side of the particulate collection filter 7. These are not specifically shown in FIG. Further, a lambda sensor 9 for detecting the existing exhaust gas / lambda value λ _A is disposed downstream of the nitrogen oxide storage catalyst 6. In order to characterize accurately, the measured value of the exhaust gas / lambda value detected by the lambda sensor 9 downstream of the nitrogen oxide storage catalyst is hereinafter referred to as an exhaust gas / lambda value λ _Am . As shown in the figure, the lambda sensor 9 can be disposed on the output side of the nitrogen oxide storage catalyst 6, but the output side of the particulate collection filter 7, that is, the particulate collection filter 7 and the SCR. It can also be arranged between the catalyst 8. Using these sensors and other sensors as necessary, the operation state of the exhaust gas purification device 2 can be comprehensively investigated, and the operation state can be adapted to the operation of the diesel engine 1. In this case, it is advantageous that no other lambda sensor is attached to the exhaust gas purification device 2 in addition to the lambda sensor 9. In particular, in accordance with the invention, the lambda sensor 9 is the only lambda sensor of the exhaust gas purification device 2, which sensor adjusts the lambda value of the air-fuel mixture that burns at least partially in the diesel engine 1. Used for.

  In order to set or detect the engine mode, an engine electronic control unit 17 is provided. The engine control device 17 obtains, on the one hand, information relating to standard engine operating values such as, for example, the rotational speed, engine load, temperature, pressure, etc. from the relevant sensor, and on the other hand, for example, EGR valve 14, air supply A control signal as an adjustment value can be transmitted to an actuator such as the exhaust turbocharger 15 of the line 3 or the throttle element. An operation value or state value adjustment function is prepared on the gas supply side and the fuel supply side. In particular, the engine control device 17 can control the fuel injector to perform the multipoint injection, and can appropriately adjust the fuel injection pressure as necessary. Furthermore, the engine control device 17 is installed to carry out a regulation and control process, whereby the engine operating value is set in a regulated or controlled state. For this purpose, the engine control device 17 can use a stored characteristic map or calculation routine or adjustment / control routine. The subsystems provided for this purpose, for example computers, memories or input / output units, are not specifically shown.

  In a similar manner, a second control device 18 is provided for the operation of the exhaust gas aftertreatment device 2 and the detection and setting of state values. The engine control device 17 and the second control device 18 are connected to each other by a bidirectional data line 19. By this method, data usable in the respective control devices can be exchanged with each other. The control devices 17, 18 can be combined into a single integrated measurement value detection and control device.

Under oxidizing conditions, the nitrogen oxide storage catalyst 6 stores NOx and SOx in the exhaust gas by chemically adhering to the laminated material mainly as nitrate ester or sulfate ester. Therefore, this is generally true in the normal operation method of the diesel engine 1 due to excess air (hereinafter referred to as the first operation mode). While NO _x storage is required to remove nitrogen oxides, SO _x storage is disadvantageous because the NO _x storage space is blocked. To maintain the NO _x removal function of the nitrogen oxide storage catalyst, it is necessary to frequently perform regeneration operation of removing the NO _x or SO _x is occluded again. In this case, the removal of the stored NOx is carried out by so-called nitrate ester regeneration, and the removal of SO _x is carried out by so-called sulfate ester regeneration. Since the concentration of NO _x in the exhaust gas is obviously higher than that of SO _x , nitrate regeneration needs to be performed at an apparently shorter interval than sulfate regeneration. Usually, the nitrate ester regeneration is performed at intervals of 30 seconds to several minutes, while the sulfate ester regeneration is preferably performed after traveling about 1000 km based on the travel distance. In both cases, it is necessary to supply at least temporarily reducible exhaust gas, that is, exhaust gas having an exhaust gas lambda value λ _A of less than one. To this end, according to the invention, the diesel engine 1 is operated in an operation mode in which the engine lambda value λ _M is smaller than 1, which is supplied with a rich air-fuel mixture. Hereinafter, this operation mode is referred to as a second operation mode. Under reduced conditions, NO _x stored during nitrate ester regeneration is liberated again and most is converted to N ₂ and NH ₃ . In sulfate regeneration, sulfur stored as sulfate is reduced to a volatile sulfur compound such as SO ₂ or H ₂ S.

For reasons of fuel consumption, it is required that the lean engine operation time in the first operation mode with the engine lambda value λ _M greater than 1 be longer. Correspondingly, it is desirable to reduce the time ratio of the second operation mode. In any case, the first operation mode is set by a normal lean operation of the diesel engine 1. However, the second operating mode with an engine lambda value λ _M less than 1 for supplying the nitrogen oxide storage catalyst 6 with reducible exhaust gas with an exhaust gas lambda value λ _A less than 1 The setting requires special measures, particularly with respect to a reliable and accurate adjustment of the engine lambda value λ _M , which will be explained in detail below. In this case, first, the method according to the present invention in carrying out nitrate ester regeneration will be additionally described with reference to FIG.

The graph of FIG. 2 shows the engine lambda value λ _M in various operating modes of the diesel engine 1 and the exhaust gas lambda value λ _Am detected by the lambda sensor 9 disposed downstream of the nitrogen oxide storage catalyst 6. The preferred time course of is shown. The progress of the engine lambda value λ _M is indicated by a straight line, and the exhaust gas lambda value λ _Am detected by the lambda sensor 9 is indicated by a broken line. Here, in the exhaust gas purification device 2, no component that significantly affects the exhaust gas / lambda value is arranged upstream of the nitrogen oxide storage catalyst 6, so the exhaust gas sent to the nitrogen oxide storage catalyst is It is assumed that the engine lambda value λ _M has the same exhaust gas lambda value λ _A as the engine lambda value λ _M.

In the first process, the first operation mode is first set in FIG. The time of the first operating mode is indicated by symbol I in FIG. When the first operation mode is working, lean exhaust gas having a high oxygen content is sent to the nitrogen oxide storage catalyst 6. This exhaust gas is supplied from, for example, a diesel engine 1 operating with an engine lambda value λ _{M of} λ _M = 3. In this case, the diesel engine 1 operates in the open loop control mode with respect to the engine lambda value λ _M. Engine operating values such as EGR rate, charge pressure, rail pressure, injection parameters for pre-injection and main injection are adjusted by characteristic map control according to the required output and load-rotation speed-operating point of characteristic map. Is done.

Most of the NO _x discharged from the diesel engine 1 and contained in the exhaust gas is stored in the catalyst material of the nitrogen oxide storage catalyst 6, preferably in the form of nitrate ester, and then removed from the exhaust gas. It is. If necessary, the NO _x slip generated from the nitrogen oxide storage catalyst 6 is at least partially rendered harmless by reduction with the SCR catalyst 8 connected downstream.

It is determined that the nitrogen oxide storage catalyst 6 has approached saturation and has, for example, increased nitrogen oxide slip to a value that is unacceptable on a sensor or model basis, or has reached a specified nitrogen oxide saturation threshold. When the prescribed release conditions are met, nitrate regeneration is started. As the release condition, for example, it is taken into consideration that the engine operation can be set within a load-rotation speed-characteristic map range with only a part of the engine load at which the full load can be set. When the release condition is met, at time t0, the operation of the diesel engine 1 is first entered into the third mode of operation with an engine lambda value λ _M slightly exceeding 1.0, eg λ _M = 1.03. Can be switched. The time of the third operating mode is indicated by the symbol III in FIG. Preferably, the switching takes place almost instantaneously, at least in a very rapid manner. In order to switch from the first operation mode to the third operation mode, the following measures are taken in detail.

  The air flow rate supplied to the diesel engine 1 is reduced to a predetermined target value based on the characteristic map. For this purpose, an independent control circuit of the engine control device 17 uses a signal about the air flow rate transmitted by the air mass sensor as a control value, and an adjustment value created by the corresponding regulator is applied to the throttle element in the air supply line 3. Implemented to work. In addition, important engine operating values such as EGR rate, charge pressure, rail pressure, pre-injection and main injection parameters, and combustion priority positions are set to values prepared for rich engine operation by characteristic map control. Adjusted. Furthermore, fuel post-injection is activated. According to the present invention, apart from the total injection amount determined by the pre-injection, main injection and post-injection, the aforementioned engine operating parameters are similarly prepared in the next operating phase in the second operating mode. Is set to the same value as The time of the second operating mode is indicated by symbol II in FIG.

Nitrogen oxide storage catalyst 6 which is saturated with oxygen during the operation in the first mode of operation described above, in the third mode of operation, substantially the exhaust gas with respect to the portion to determine the exhaust gas lambda value lambda _A Pass through unchanged. Accordingly, the exhaust gas lambda value λ _Am transmitted by the lambda sensor 9 is a nitrogen oxide occlusion as shown in the figure, apart from a slight time delay and a certain degree of lambda transition smoothness. Exhaust gas lambda value λ _A upstream of the catalyst 6, and therefore exactly matches the engine lambda value λ _M. This is utilized in accordance with the present invention for the diesel engine 1 to transition from an open loop control mode to a closed loop control mode with respect to the engine lambda value λ _M. The adjustment in the third operating mode is in this case preferably carried out as an adaptive pilot control adjustment, which will be described in detail below.

The measurement signal provided from the lambda sensor 9 is converted into a lambda value (exhaust gas / lambda value λ _Am ) by the second control device 18 in accordance with the maintained characteristic curve and transmitted to the engine control device 17. The The exhaust gas lambda value λ _Am so measured by the lambda regulator implemented in the engine control device 17 is used as an adjustment value, and the standard engine lambda value λ _M for the third operating mode is used. Compared with the target value. Based on the comparison result, an adjustment value is determined that acts on the fuel injector and determines the total injection amount. In order to adjust the total injection amount as the adjustment value by the pilot control, a correction value that affects this is provided, and this correction value is read from the write-read memory, and as a whole, the correction value is adjusted. The injection quantity results from a part coming out of the lambda regulator and a part determined by a correction value, which correction value is additively or multiplicatively linked to the regulator part. In this case, multiplicative coupling is advantageous.

In accordance with the present invention, the error identified between the measured exhaust gas lambda value λ _Am and the target value of the standard engine lambda value λ _M for the third mode of operation is corrected as necessary. By changing the value, it is considered that the error is at least approximately zero as a result of the modified value change. For this, the value of the air flow provided by the air mass sensor is evaluated. The total injection amount is adjusted so that the target value of the engine lambda value λ _M is calculated based on the value of the air flow rate. In this case, the total injection amount is determined by a correction value that is appropriately determined. . The old correction value is then replaced with the newly learned correction value, which is changed as necessary, and overwritten in memory. Therefore, the regulator only needs to adjust the extra current that occurs. The operation of the regulator is reduced accordingly. The overwriting of the correction value can be omitted when there is only a small change or when a large change occurs in the engine operation due to a load request requested by the driver, for example.

In this connection, it is particularly preferable that only the post-injection amount is post-adjusted as necessary, and the values of the pre-injection amount and the main injection amount adjusted by the pilot control are kept constant. Therefore, as the adjustment value for accurately setting the engine lambda value λ _M , in this particularly preferred embodiment, only the entire injection amount portion allocated to the post injection amount is used.

  When the adjustment process of the lambda value in the third operation mode is performed, this is considered to be performed, for example, when the adjustment error falls below the minimum value, and the third operation mode ends at the time t1. The engine operation is switched to the second operation mode. The excessive vibration in the third operation mode is usually attenuated in a short time after 1 to 3 seconds, for example. Therefore, the engine operation in the third operation mode can be called an operation mode transition stage, This stage is inserted between the first operation mode and the second operation mode.

In the second operation mode, a rich engine lambda value λ _M of 0.95 is set in the diesel engine 1, and the diesel engine 1 is switched to the open loop control mode with respect to the engine lambda value λ _M. For this reason, the regulator output is fixed to the value at the end of the third operation mode, and the total injection amount increases, that is, the corresponding pilot control value increases. In order to check the range of the rise, preferably the value of the air flow provided from the air mass sensor is newly evaluated and the target value for the new reduced engine lambda value λ _M is calculated based on the value of the air flow. Thus, the total injection amount is adjusted. In this case, it is particularly advantageous that only the post-injection amount is adjusted and the pre-injection amount and the main injection amount are kept constant. Therefore, the adjustment value of the pilot control adjustment of the engine lambda value lambda _M, of the total injection quantity, only the portion allocated to the post-injection amount is used. The other engine operating parameters already have the values required for the rich combustion mode of the second operating mode and have already been adjusted in the third operating mode described above, and therefore remain unchanged.

In the second operation mode, actual nitrate ester regeneration of the nitrogen oxide storage catalyst 6 is performed by the reducible exhaust gas sent to the nitrogen oxide storage catalyst 6. In this case, NO _x stored in the nitrogen oxide storage catalyst 6 is reduced to N ₂ and NH ₃ . In this case, the liberated NH ₃ is sent to the next SCR catalyst 8 where it is occluded. As a result of the reduction process of the nitrogen oxide storage catalyst 6 using the reducing agent, the exhaust gas has a component that does not reduce downstream of the nitrogen oxide storage catalyst 6. The gas lambda value λ _Am is measured. When the stored NO _x is substantially reduced, the reducing agent contained in the rich exhaust gas gradually disappears, the exhaust gas lambda value λ _Am decreases, and the engine lambda value upstream of the nitrogen oxide storage catalyst 6 closer to the λ _M. Thereby, the end of the regeneration process can be detected by evaluating the measurement value supplied from the lambda sensor 9. Preferably, when the exhaust gas lambda value λ _Am detected by the lambda sensor 9 falls below a definable threshold, the second operation mode, and therefore the nitrate regeneration of the nitrogen oxide storage catalyst 6 is at time t2. It is finished, and the condition of the first operation mode is adjusted again.

In the method of learning type pilot control of the engine lambda value λ _M in the second and third operation modes, it is preferable that the correction value learned in the third operation mode is a load-speed-characteristic map diesel The current operating point of the engine 1 is improved by being assigned to a certain characteristic map range. For this purpose, it is advantageous if the load-speed-characteristic map is divided into characteristic map ranges of defined or definable values. A fine division of the load-speed-characteristic map improves the accuracy of pilot control, but increases costs by increasing the level of detail. It is preferable to divide the characteristic map range into 10-40.

  In order to further improve the accuracy, it is possible to prepare to consider the gas flow time in the air path and / or the exhaust gas purification device 2 when evaluating the measurement signal of the air mass sensor and / or lambda sensor 9. By correcting the dead point, the leading of the measurement signal of the air mass sensor due to the flow time can be corrected with respect to the measurement signal of the lambda sensor 9. For this purpose, a model for simulating the time difference between the measurement signal of the air mass sensor and the injection time of each total injection amount or the post-injection amount and the time point of the associated lambda signal is prepared. The pilot control of the quantity or post-injection quantity can be modified dynamically.

Below, the preferable method at the time of implementing the sulfuric ester reproduction | regeneration of the nitrogen oxide storage catalyst 6 is demonstrated. In this case, based on the time lapse graph shown in FIG. 3, the difference from the above-described nitrate ester regeneration method is particularly discussed. In the time course graph of FIG. 3, the time course of the engine lambda value λ _{M and} the time course of the lambda value λ _Am in the exhaust gas measured downstream of the nitrogen oxide storage catalyst are the same as the graph of FIG. Is shown in

The sulfuric acid ester regeneration of the nitrogen oxide storage catalyst 6 is performed when it is confirmed that the sulfur oxide is stored in an unacceptably high amount. The confirmation can be made, for example, on a model basis or based on fuel consumption. Sulfate ester regeneration is performed in a manner similar to nitrate ester regeneration. The substantial difference is that the temperature of the exhaust gas or nitrogen oxide storage catalyst 6 rises to about 650 ° C. and a strong enrichment to an engine lambda value λ _{M of} about 0.8 to 0.9 is set. That is. Furthermore, the concentration time is increased compared to nitrate regeneration. Another difference is that the operating phase switches between the rich engine lambda value λ _M and the lean engine lambda value λ _M several times in succession, preferably during a temperature rise. . As a result, it is possible to decompose the sulfuric ester relatively stably. Preferably, sulfate ester regeneration is carried out in a time-related manner with thermal particulate collection filter regeneration by burning soot. This reduces the number of heating processes and fuel consumption.

  The temperature increase is achieved by setting a so-called post-combustion injection that occurs early and / or a non-combustion post-injection that occurs late. In the operating cycle, the exhaust gas exhaust temperature can be directly increased by early post-injection at a crankshaft angle of about 10 degrees to about 40 degrees before top dead center. In the operating cycle, late combustion at a crankshaft angle of about 45 degrees to about 120 degrees after top dead center causes non-burning components to be mixed into the exhaust gas, and these components are mixed with the oxidation catalyst 5 and / or Combustion occurs due to oxidation by residual oxygen contained in the exhaust gas in the nitrogen oxide storage catalyst 6, thereby causing heating of the exhaust gas or heating of the catalyst.

  In order to carry out the regeneration of the sulfuric ester, the engine operation parameters by pilot control defined based on the characteristic map are used, and the first operation mode to the third operation are performed in the same manner as described in connection with the regeneration of the nitrate ester. Switching to the mode is performed. Similarly, the correction value is learned when the third operation mode in the operation mode transition stage is set. However, various sets of correction values for performing nitrate ester regeneration and correction values for performing sulfate ester regeneration can be prepared.

Similar to nitrate ester regeneration, in the sulfuric acid ester regeneration after the rich engine lambda value λ _M is set in the second operation mode, the exhaust gas has a component that reduces downstream of the nitrogen oxide storage catalyst 6. The lambda sensor 9 first measures an exhaust gas / lambda value λ _{Am of} 1.0. When the stored NO _x and SO _x are substantially reduced, the reducing agent contained in the rich exhaust gas gradually disappears, the exhaust gas / lambda value λ _Am decreases, and upstream of the nitrogen oxide storage catalyst 6. It approaches a certain engine lambda value λ _M. However, unlike the nitrate regeneration, the exhaust gas lambda value lambda _Am when very close to the engine lambda value lambda _M, in accordance with the present invention, maintained for rich engine lambda value lambda _M for a while At time t2, the diesel engine mode is switched from the open loop control mode to the closed loop control mode with respect to the lambda value of the air-fuel mixture. At the time t3 of engine operation, after the elapse of the entire configurable time, for example about 20 seconds, in the second operating mode with a rich engine lambda value λ _M , the engine mode is again in the open-loop control mode for the air / fuel ratio. 1 operation mode I. The operating phase of the second operating mode with the rich engine lambda value λ _M is thereby divided into two parts. In FIG. 3, the first part, indicated by the symbol IIa, causes the diesel engine 1 to operate in an open loop control mode with respect to the rich engine lambda value λ _M. The second part, indicated by symbol IIb, is that the diesel engine 1 operates in a closed loop control mode with respect to the rich engine lambda value λ _M and the engine operation from the first part IIa or the third operation mode. The pilot value of the parameter is inherited.

In order to remove the stored SO _x as completely as possible, after a relatively short time of about 5 to 15 seconds in the first operation mode, the setting of the operation mode transition stage and the subsequent open loop control The process according to the second mode of operation comprising one part IIa and the second part IIb of closed loop control is repeated without changing the temperature rise. In particular, 5 to 20 repetitions are prepared.

  After the advantageously settable number of repetitions, the measures for raising the exhaust gas or catalyst temperature are finished and the diesel engine 1 enters the normal mode with frequent regeneration of nitrate esters.

In the second operation mode, in order to increase the accuracy of the lambda controller in the second operating portion IIb, preferably, the characteristic curve of the lambda sensor 9 is maintained, is arranged to adjust for intersection sensitivity to H ₂ ing. Thereby, for example, when a rich combustion mode has continued for a long time as a result of a side reaction such as a water gas shift reaction, a possibility that a measurement signal of the lambda sensor 9 is distorted is taken into consideration. This method ensures that an adjustment due to an incorrect engine lambda value λ _M is avoided.

Overall, as a result of the lambda adjustment prepared in the case of carrying out nitrate ester regeneration or sulfate ester regeneration using the lambda sensor 9 arranged downstream of the nitrogen oxide storage catalyst 6 according to the present invention, And accurate lambda setting is possible. However, as a result of the special learning type pilot control that is further prepared in a preferred form, only the pilot control mode can be used whenever necessary. This improves the safety of the system when normal operation is impossible due to, for example, an unfavorable driving condition or a failure of the lambda sensor 9.

Claims (16)

In a method for operating a diesel engine (1) including an exhaust gas purification device (2) having a nitrogen oxide storage catalyst (6),
The air-fuel mixture having a lambda value is at least partially combusted in the combustion chamber of the diesel engine (1), and the generated exhaust gas is sent to the nitrogen oxide storage catalyst (6), and the air-fuel mixture is larger than 1. Starting from operation of the diesel engine (1) in a first operating mode having a first lambda value, the mixture is less than 1 for regeneration of the nitrogen oxide storage catalyst (6). The operation of the diesel engine (1) in the second operation mode having a lambda value of 2 is set, and an operation mode transition stage is inserted immediately before the setting of the second operation mode. The diesel engine (1) is operated in a third operating mode that is adjusted to a third lambda value that is lower than that in the first operating mode and slightly higher than 1. A Le method of operating the engine (1),
In the third operation mode, closed-loop control of the diesel engine (1) is performed with respect to the lambda value of the air-fuel mixture, and the nitrogen oxide storage catalyst (6) in the exhaust gas purification device (2). An exhaust gas lambda value (λ _Am ) is detected by a lambda sensor (9) disposed downstream of the lambda sensor, and the lambda value is a target value that can be defined for the third lambda value in the closed loop control. There use as an adjustment value for adjusting,
In the first and second operating modes, an open loop control operation of the diesel engine (1) is performed with respect to the lambda value of the mixture. A target value is provided for the second lambda value, and in the second and third operation modes, pilot control of the engine operation value as an adjustment value that affects the lambda value of the air-fuel mixture is performed. performed, the second and the third lambda value, by the pilot control, characterized in that that will be adapted to at least substantially reached the target value respectively provided, the method of claim 1. The method according to claim 2 , wherein the pilot control is designed as a learning type pilot control so that a correction value that can be changed adaptively and affects the adjustment value is prepared. In the second and third operation modes, pilot control of the total injection amount of fuel injected into the combustion chamber of the diesel engine (1) in the operation cycle is performed and detected by an air mass sensor device. Depending on the air flow rate supplied to the diesel engine (1) for at least partial combustion of the air-fuel mixture, the second and third lambda values are at least approximately equal to their respective target values. 4. A method according to any one of claims 1 to 3 , characterized in that the method is reached. The method according to claim 4 , wherein the air flow rate detected by the air mass sensor device is used as an adjustment value for adjusting a settable air flow rate target value. The total injection quantity, characterized in that after and a injection quantity injected in the later injection following the main injection and the main injection quantity injected in the main injection, the method according to claim 4 or 5 . The method according to claim 6 , wherein the post-injection amount is used as an adjustment value for adjusting the target value of the second or third lambda value. In the third operation mode, an error between the exhaust gas lambda value resulting from the pilot control and the target value of the third lambda value is investigated, and if necessary, the error can be at least almost ignored. The method according to claim 3 , wherein the correction value that can be changed adaptively is changed to be in a range. Are ready engine operating characteristic map, the characteristic map has a characteristic map ranges of possible values, characterized in that each correction value is assigned to that value, to claim 3-8 The method described. When the pilot control for setting the second or third lambda value is engine operation in a specified characteristic map range, the characteristic map is related to regeneration of the nitrogen oxide storage catalyst (6). 10. A method according to claim 9 , characterized in that a correction value assigned to the range is used. In the second operation mode, at least one of an engine operation value, an exhaust gas recirculation rate, and an intake throttle rate is adjusted in the same manner as the third operation mode set immediately before the second operation mode. The method according to claim 1 . The said 2nd operation mode WHEREIN: The said main injection amount is adjusted similarly to the said 3rd operation mode set immediately before it, The Claim 6 characterized by the above-mentioned. Method. In the second operation mode, when the nitrate ester regeneration for removing the stored nitrogen oxides from the nitrogen oxide storage catalyst (6) is performed, downstream of the nitrogen oxide storage catalyst (6). When the exhaust gas / lambda value (λ _Am ) detected by the arranged lambda sensor (9) is monitored to see if it is below a settable threshold, and is below the settable threshold 13. The method according to any one of claims 1 to 12 , characterized in that the mode of the diesel engine (1) is returned to the first operating mode. In the second operation mode, when the sulfuric acid ester regeneration for removing the stored sulfur oxide from the nitrogen oxide storage catalyst (6) is performed, downstream of the nitrogen oxide storage catalyst (6). The exhaust gas lambda value (λ _Am ) detected by the arranged lambda sensor (9) is monitored whether it falls below a settable threshold, and after the settable threshold is fallen, while at least approximately maintaining the second lambda value, claim, characterized in mode that is switched to the from the open loop control mode to the closed loop control mode with respect to the lambda value of the mixture diesel engine (1) 1-13 The method as described in any one of. An exhaust gas purification device (2) having a nitrogen oxide storage catalyst (6) and a control device (17, 18) for carrying out the method according to any one of claims 1 to 14 , wherein the exhaust gas The lambda sensor (9) arranged downstream of the nitrogen oxide storage catalyst (6) in the purification device (2) is at least partially combusted in the combustion chamber of the diesel engine (1). A diesel engine which is the only lambda sensor provided in the exhaust gas purification device (2) for adjusting the lambda value of the air. 16. A particulate collection filter (7) is disposed between the nitrogen oxide storage catalyst (6) and the lambda sensor (9) in an exhaust gas purification device (2). Diesel engine as described in

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