Emission reductions through control of reagent release

Abstract

Procedure, comprehensive: Operating (502) an engine (104) with an aftertreatment system, wherein the aftertreatment system is a NO x -Reduction chemical storage device (112) includes, Performing an NH3 slip attenuation operation (506) in response to an impending NO x -Reduction chemical release from NO x -Reduction chemical storage device (112); the procedure further includes: an assessment (504) of the imminent NO x -Reduction chemical release by determining (514) that a NO x-reduction chemical storage device (112) stored NH3 quantity exceeds a release threshold, and by determining (516) that an engine operating request generates a nominal exhaust gas temperature that is higher than an NH3 release temperature, the method further comprising reducing (518) an engine torque value such that the nominal exhaust gas temperature is shifted below the NH3 release temperature.

Description

Technical area

[0001] The technical field generally concerns emission control in diesel engines and more specifically concerns controlling the release of excess reductant from an aftertreatment catalyst. background

[0002] Modern emissions requirements for many internal combustion engines have made aftertreatment systems necessary in many applications. Some aftertreatment systems work by storing a reactant, such as NO x-reducing agent - on a catalyst surface so that subsequent exhaust gases can react with the stored reactant. However, currently available systems suffer from several disadvantages. The amount of reactant that can be stored on the catalyst varies under different operating conditions, including variability with temperature. In certain systems, the storage capacity of the catalyst decreases with temperature to such an extent that the reactant can be released in unreacted form. Many reactants are themselves regulated by law or are considered undesirable for direct release to the atmosphere. Therefore, currently available systems must choose between a number of less desirable solutions, e.g.Oversizing the storage catalyst, adding a purification catalyst, operating the engine in a very conservative manner with inhibited power output, and the possibility of operating the aftertreatment system as a less efficient system while simultaneously reducing emissions more significantly in other areas, such as during the combustion process. Each of these solutions increases the cost or reduces the performance and / or reliability of the application. Therefore, further technological advances in this area are desirable.

[0003] DE 10 2006 025 257 A1 describes a method for operating an SCR catalyst arranged in an exhaust system of an internal combustion engine, which is suitable for at least partially storing a chemical reducing agent and, with the aid of the chemical reducing agent, reducing nitrogen oxides (NOx) in the exhaust gas. The chemical reducing agent or a precursor thereof is introduced into an exhaust gas of the internal combustion engine upstream of the SCR catalyst. It is provided that a loading level of the SCR catalyst with the reducing agent is reduced depending on a current or requested operating state of the internal combustion engine and / or components of the exhaust system.

[0004] DE 10 2009 040 787 A1 describes a method for controlling the operation of a vehicle system having an internal combustion engine and a catalytic emission control device connected in an outlet of the engine, the method comprising: supplying reductant to the emission control device in response to vehicle operating conditions and increasing the inlet NOx of the emission control device in response to a reductant release from the emission control device Summary

[0005] The invention is as defined in the independent claim. Preferred embodiments of the invention are defined in the subclaims.

[0006] One embodiment is a specific reactant conversion process that neutralizes a portion of the stored reactant prior to changing the catalyst storage capacity. Other embodiments include specific methods, systems, and devices for reducing reactant release amounts. Further embodiments, configurations, objects, features, advantages, aspects, and benefits will become apparent from the following description and figures. Short description of the characters Fig. Figure 1 is a schematic representation of an application with a reactant release reduction system. Fig. Figure 2A is a representation of nominal pre- and post-injection processes. Fig. Figure 2B is a representation of adjusted pre- and post-injection processes. Fig. Figure 3 is a schematic diagram of a processing subsystem. Fig. Figure 4 is a schematic flow diagram of a method for reducing reactant release. Fig. Figure 5 is a schematic flow diagram of a procedure for mitigating an impending ammonia emission. Description of illustrative embodiments

[0007] For the purpose of a better understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the figures, and technical terms will be used to describe them. It should be understood, however, that this is not intended to limit the scope of the invention, but rather to encompass all modifications and further variations of the illustrated embodiments and any further applications of the principles of the invention presented herein that would normally occur to one skilled in the art to which the invention pertains.

[0008] Fig. 1 is a schematic representation of a system 100 with an application 102 containing a reactant release reduction system. Fig. The application 102 shown in Figure 1 is a truck application with a diesel engine 104, although any application with a NO x generating engine 104 is conceivable. In certain embodiments, the system 100 includes the internal combustion engine 104, which produces an exhaust stream 106 having a NO x -amount. In some embodiments, the system 100 includes a reductant introduction device 108 that introduces a reductant 110 into the exhaust stream 106. In some embodiments, the reductant 110 includes ammonia and / or an ammonia precursor such as urea or any NO x-reducing chemical. In some embodiments, the system 100 further includes a reductant storage device 112 that stores reductant 110 during some or all of the engine operating conditions. The reductant storage device 112 includes a catalyst and a substrate, and in some embodiments includes a catalyst that adsorbs ammonia at certain temperatures and releases ammonia at certain, higher temperatures. In certain embodiments, the ammonia reacts with NO coming from the engine 104. x, which at some operating points results in an increased ammonia supply capacity beyond that provided by the reductant introduction device 108. In certain embodiments, the reductant storage device 112 further includes other components of the exhaust system that can accumulate reductant, e.g., an exhaust pipe, a catalyst, and / or another component such as a particulate filter (not shown).

[0009] In some embodiments, system 100 further includes a controller configured to perform certain operations to reduce emissions, including emitted reductant 110, which may flow from system 100 unreacted with exhaust stream 106. In certain embodiments, controller 114 forms part of a processing subsystem including one or more computing devices including memory, processing, and communication hardware. Controller 114 may be a single device or a distributed device, and the functions of the controller may be performed by hardware or software.

[0010] In some embodiments, the controller includes one or more modules configured to functionally perform the operations of the controller. In some embodiments, the controller includes an ammonia storage module, an ammonia release prediction module, a NO x -Rise setting module, a NO x-Slope control module, a catalyst reaction rate module, and / or a catalyst aging estimation module. The present description with modules emphasizes the structural independence of the aspects of the controller 114 and illustrates a grouping of operations and responsibilities of the controller 114. Other groupings that perform similar overall operations are within the scope of the present application. Modules may be implemented as hardware and / or software on a computer-readable medium, and modules may be distributed across various hardware or software components. More detailed descriptions of certain embodiments of operations of the controller 114 are described in the Fig. 3 referencing section.

[0011] In some embodiments, the internal combustion engine 104 includes a system (not shown) for implementing variable valve timing (VVT) and the NO x The amount of exhaust gas is increased by controller 114 by controlling the VVT ​​system to increase an effective compression ratio and / or controlling the VVT ​​system to reduce a combustion residue in a combustion cylinder of the internal combustion engine. The use of a combustion residue in the cylinder is sometimes referred to as "internal exhaust gas recirculation," and reducing the combustion residue in the cylinder reduces the amount of internal exhaust gas recirculation.

[0012] In certain embodiments, the internal combustion engine 104 includes a turbocharger 116 and an intercooler 118. The turbocharger 116 is shown schematically split for clarity to physically separate the intake flow 117 from the exhaust flow 106 into Fig. 1, although the compressor side and the turbine side of the turbocharger 116 are typically arranged in close proximity in a housing and connected by a shaft. In certain embodiments, the NO x-Amount is increased by the control unit 114 by controlling an actuator configured to reduce a heat exchange rate of the charge air cooler 118. For example, the charge air cooler 118 may include a cooling liquid 120 (e.g., the radiator fluid) and a coolant pump 122, and the heat exchange rate of the charge air cooler 118 is reduced by means of the coolant pump 122 by reducing the coolant discharge pressure to the charge air cooler 118. Any other method for reducing the heat exchange rate of the charge air cooler 118 is also conceivable in this case, including at least one of bypassing coolant past all or part of the charge air cooler 118, operating a valve (not shown) to slow down a flow through the charge air cooler 118, and / or bypassing all or part of the inlet flow 117 past the charge air cooler 118.The effect of reducing the heat exchanged by the charge air cooler 118 is a higher temperature in the intake manifold 130, resulting in higher NO. x -generation by the motor 104.

[0013] In certain embodiments, the internal combustion engine 104 includes a first turbocharger 116 and a second turbocharger 124, and the NO x -Amount is increased by means of the control unit 114 by controlling the first turbocharger 116 and the second turbocharger 124 so that compression loads are redistributed in such a way that a temperature in the intake manifold 130 increases. In the representation of the Fig. 1, for example, the second turbocharger 124 compresses the intake stream 117 downstream of the charge air cooler 118, and increasing the compression load of the second turbocharger 124 as shown will increase the temperature in the intake manifold 130 under many operating conditions of the engine 104.

[0014] In certain embodiments, the internal combustion engine 104 includes a common rail fuel system (not shown) and the NO x The amount of NO is increased by means of the control unit 114 by controlling the common rail fuel system to increase a fuel rail pressure. In certain embodiments, the internal combustion engine 104 includes a common rail fuel system and the NO supplied by the engine 104 xThe fuel quantity is increased by means of the control unit 114 by controlling the common rail fuel system to influence a post-fuel injection event and / or a pre-fuel injection event. For example, the control unit 114 can change an injection timing and / or a quantity of the post-fuel injection event and / or the pre-fuel injection event so that more fuel is delivered earlier compared to a nominal injection event, which under many operating conditions of the engine 104 leads to the generation of additional NO x leads.

[0015] In certain embodiments, the internal combustion engine 104 includes a variable geometry turbocharger 116 and the NO xThe amount of NOx is increased by the control unit 114 by controlling the VTG turbocharger 116 to increase the boost pressure. In certain embodiments, the system further includes an exhaust gas recirculation (EGR) flow 126 and an EGR valve 128, and the NOx supplied by the engine 104 x -Amount is increased by reducing an amount of EGR flow 126.

[0016] In an alternative embodiment, the NO supplied by the engine 104 x The amount of EGR is increased by increasing the temperature of recirculated exhaust gas introduced into the intake manifold. In one example, the EGR flow 126 is partially or completely bypassed by an EGR cooler (not shown). In another example, coolant flow on the downstream side of the EGR cooler is reduced, so that the net heat exchange in the EGR cooler is reduced.

[0017] Fig. Figure 2A is a representation of nominal pre- and post-injection processes. In the representation of the Fig. 2A, the pre-injection process 202 begins approximately 5 degrees before top dead center (TDC) and the post-injection process 204 begins at approximately 35 degrees after TDC. The representation of the Fig. Figure 2B shows the pre-injection process 206 shifted to approximately 10 degrees before TDC and with an increased size relative to the nominal process 202. The representation of the Fig. 2B further shows that the post-injection event 208 is shifted to approximately 20 degrees after TDC, and shows the post-injection event 208 having a similar magnitude compared to the nominal post-injection event 204. In certain embodiments, adjustments to the pre-injection events 202, 206 have a greater effect on NO x-Generation as adjustments to the post-injection events 204, 208. Any other adjustments known in the art are conceivable, including, without limitation, adjustments to the pre-injection 202, the post-injection 204, and / or the main injection event 210 to maintain a similar output torque for the engine 104 as would otherwise be achieved by the nominal injection events 202, 204, 210.

[0018] Fig. 3 is a schematic diagram of a processing subsystem 300 including a controller 114.

[0019] In certain embodiments, the controller 114 includes a reductant storage module 318 (or an ammonia storage module 218) that determines whether a reductant storage device 112 contains a stored amount of the reductant 110. In certain embodiments, the reductant storage module 318 determines whether the NO x-reduction chemical storage device 112 a stored amount of NO x -reducing chemical 110. In certain embodiments, the reductant storage module 318 estimates an amount of injected reductant remaining in the exhaust pipe, catalyst, and / or other components. For example, the reductant storage module 318 may determine that a percentage of the injected reductant remains in the exhaust pipe, where the percentage depends on an ambient temperature, an exhaust temperature, an exhaust gas flow rate, and / or a NO x -reductant chemical injection rate. In certain embodiments, the reductant storage module 318 determines whether the NO x -reduction chemical storage device a stored amount of NO x -reduction chemical by determining whether the NO x-reduction chemical storage device has reached a time threshold (e.g. a storage time threshold 220) at a temperature value below a NO x -reducing chemical storage temperature threshold 314. For example, the catalyst 112 may be known to store only a negligible amount of reductant at higher temperatures (e.g., above 275°C), and the reductant storage module 318 may estimate that no reductant storage occurs above the temperature threshold 314. The threshold 314 described here may be a single value, a range of values, and / or a function of values. For example, a given temperature may not initially release NH3 from the catalyst, but may cause release to occur over time, which has the effect of the temperature threshold 314 decreasing over time as the catalyst remains warm and begins to release the NO x-reduction chemical. In addition, at high levels of stored NO x -reduction chemical a temperature threshold 314 lower than at lower values ​​of stored NO x -reduction chemical, since the rising temperature reduces the storage capacity of the catalyst and thus the stored NO x -reduction chemical.

[0020] In certain embodiments, the controller 114 includes a reductant release prediction module 302 that determines an impending reductant release. In certain embodiments, the reductant release prediction module 302 predicts an impending NO xReductant release may be determined by determining that a load value 306 of the engine has increased above a threshold. For example, the load value 306 may be a torque or power value known to be highly likely to cause an exhaust temperature to exceed the temperature threshold 314 and thereby release stored reductant, and the reductant release prediction module 302 determines that a reductant release is imminent when the engine 104 exceeds the load value 306. In certain embodiments, the engine load value 306 may use a filtered engine load and / or the reductant release prediction module 302 may require the engine load to exceed the load value 306 for a period of time before determining that a reductant release is imminent.In certain further embodiments, the reductant release prediction module 302 determines an impending NO. x -Reduction chemical release by determining that a temperature value 310 for the catalyst has risen above a threshold. The temperature threshold for the catalyst may be a different temperature than the reductant temperature threshold 314, and may be a value that changes during operation depending on the length of time at a temperature and / or the amount of NO stored on the catalyst. xReducing chemical and may further include an absolute or relative temperature value. For example, an increase in catalyst temperature of 50°C at nearly any temperature may significantly change the storage capacity of catalyst 112 and / or vaporize reductant accumulated in an exhaust pipe, therefore, in certain embodiments, reductant release prediction module 302 may determine that a reductant release is imminent when the exhaust temperature and / or catalyst temperature value 310 rises above a threshold. In certain embodiments, reductant release prediction module 302 determines an imminent reductant release based on, either exclusively or additionally, a time derivative 308 of engine load and / or a time derivative 312 of the catalyst temperature value.

[0021] In certain embodiments, the controller 114 includes a NOx -Slope setting module 322, which is a NO x -increase amount 304 is determined in response to the stored amount of reductant or the stored reductant amount 316 and the impending reductant release. In certain embodiments, the NO x -Rise setting module 322 the NO x -Increase amount 304 as a NO x -Increase schedule 326 based on the stored amount 316 of ammonia or reductant. In certain embodiments, the NO x -Rise plan 326 a fixed NO x -Rise time duration 328. In certain embodiments, the NO x -Rise plan 326 a NO x -Rise profile based on an expected reductant release profile from the catalyst 112 and / or another source of stored reductant.

[0022] In certain embodiments, the controller 114 includes a NO x-Surge control module 324, which receives a NO supplied by the engine 104 x -Amount in response to the NO x -increase amount 304. In certain embodiments, the NO x -Rise control module 324 the NO x -emissions amount from the engine 104 by decreasing an exhaust gas recirculation rate 330, by advancing a fuel injection timing value 332 and / or by increasing an intake manifold temperature value 334. In certain embodiments, the NO x -Rise control module 324 the NO x -emissions from the engine 104 by increasing a fuel rail pressure, by adjusting a post-fuel injection event, by adjusting a variable valve timing, by increasing a boost pressure, by adjusting a pre-fuel injection event, and / or by adjusting an air / fuel ratio for the engine. In certain embodiments, the NO x -Rise control module 324 the NOx -emissions amount from the engine 104 by reducing a combustion residue in a combustion cylinder of the internal combustion engine, by reducing a heat exchange rate of a charge air cooler, by increasing a boost pressure value, and / or by controlling a first turbocharger and a second turbocharger to redistribute compression loads such that an intake manifold temperature is increased. In an exemplary embodiment, the ammonia release prediction module 302 predicts ammonia release based on the stored reductant amount 316 and a nominal temperature determined in accordance with operating conditions or requested operating conditions of the engine 104. The ammonia release prediction module 302 in the example commands a torque value 346 such that the exhaust gas temperature does not exceed a temperature that excessively releases ammonia from the catalyst.

[0023] In certain embodiments, the controller 114 further includes a catalyst reaction rate module 336 that determines an unreacted reductant amount 338 and the NO x -Slope determination module 322 further determines the NO x -increase amount 304 in response to the unreacted reductant amount 338. The unreacted reductant amount 338 can be derived from the incoming NO x , the reductant, and the temperature of the catalyst 112 via kinetic modeling of the catalytic reaction, through lookup tables based on experimental data, or through other reaction rate determination means. In certain embodiments, the reductant storage module further determines that the NO x -reduction chemical storage device a stored amount of NO x -reduction chemical 316, by further determining a time integral 344 of the unreacted NO x-Reduction chemical amount 338 is determined over time.

[0024] In certain embodiments, the controller 114 further includes a catalyst aging estimation module 340 that determines a catalyst aging value 342, and the catalyst reaction rate module 336 is further configured to determine the unreacted reductant amount in response to the catalyst aging value 342. Catalyst aging over time can be readily modeled using aging processes and data generally available from in-use systems 100. Aging of the catalyst 112 affects the reaction rate of NO moving through the exhaust. x with reducing agent and further impairs the storage capacity of the catalyst 112. In certain embodiments, the NO x -Rise setting module 322 the set NO x-Rise time period 328 based on the estimated catalyst aging value 342. For example, the catalyst aging value 342 may have been determined as a value that determines the reaction rate of NO x with reductant, causing unreacted reductant 338 to accumulate more rapidly on catalyst 112. Further, catalyst aging value 342 may be determined as a value indicative of reduced catalyst storage capability, which reduces the maximum value for stored reductant amount 316. One or more catalyst aging impacts may be estimated in a given system 100, and catalyst aging may not be used in certain systems 100.

[0025] Fig. 4 is a schematic flow diagram of a method 400 for reducing reactant release. In certain embodiments, the method 400 includes an operation 402 for operating an engine with an aftertreatment system, wherein the aftertreatment system generates a NO x -reduction chemical storage device. In certain embodiments, the procedure 400 further includes an operation 404 to determine whether the NO x -reduction chemical storage device. In certain embodiments, if the NO x -reduction chemical storage device, further comprising an operation 406 for determining whether a reductant release is imminent. In certain embodiments, if a reductant release is imminent, the procedure 400 further comprises an operation 408 for setting a NO x-increase amount and an operation 410 for increasing a NO x -Emissions of the engine based on the NO x -Increase in quantity.

[0026] Fig. 5 is a schematic flow diagram of a procedure 500 for mitigating an impending ammonia release. The procedure 500 includes an operation 502 for operating an engine with an aftertreatment system, wherein the aftertreatment system generates a NO x -reduction chemical storage device. The procedure 500 includes an operation 504 for determining an impending NO x -Reduction chemical release from the NO x -reduction chemical storage device and an operation 506 for performing an NH3 slip mitigation operation in response to the impending NO x -Reduction chemical release.

[0027] In one embodiment, the NH3 slip mitigation operation 506 includes a determination 508 of whether a NO x-rise attenuation is performed, and an operation 510 for determining a NO x -increase amount and an operation 512 for increasing the NO supplied by the engine x based on the NO x -increase amount in response to the determination 508 having a positive (YES) result. In certain embodiments, the NH3 slip mitigation operation 506 further includes an operation 514 for determining that a NO x-reduction chemical storage device exceeds a release threshold, and an operation 516 for determining that an engine operating request produces a nominal exhaust temperature above an NH3 release temperature. In response to operations 514, 516 producing a positive (YES) determination, the NH3 slip mitigation operation 506 further includes an operation 518 for decreasing an engine torque value such that the nominal exhaust temperature is shifted below the NH3 release temperature. The nominal exhaust temperature includes at least one of an estimated exhaust temperature and a measured exhaust temperature.

[0028] For example, operation 514, which determines that a signal on the NO x -reduction chemical storage facility exceeds a release threshold, a model or an estimate that ammonia on a NO xAdsorption catalyst or selective catalytic reduction (SCR) catalyst in an amount that, if released, would exceed a permissible ammonia slip rate. The permissible ammonia slip rate is determined according to regulatory requirements, industry standards, and / or customer conditions or requirements or marketing considerations. A simple model includes a determination that the catalyst is at a storage temperature for a specified period of time, although more sophisticated ammonia storage models are known in the art.

[0029] The nominal exhaust temperature may be a measured exhaust temperature and / or may include an estimated exhaust temperature (e.g., a steady-state estimate) corresponding to current or requested engine operation. For example, there may be an operator request for 1000 foot-pounds (1356 Nm) of torque, resulting in a steady-state temperature at other current operating conditions that results in a nominal example exhaust temperature of 400 F (204°C), even though the engine is currently producing less than 1000 foot-pounds (1356 Nm) of torque at a lower exhaust temperature. The engine operation derate operation 518 includes selecting a torque value below the requested torque value such that the exhaust temperature (either currently measured or steady-state estimated) remains below a temperature at which stored NH3 would be released.The torque value can be increased to the level of the operator request if the amount of NH3 stored on the catalyst has been reduced.

[0030] As can be seen from the figures and the above description, a variety of embodiments according to the present invention are conceivable.

[0031] One embodiment is a method comprising operating an engine with an aftertreatment system, wherein the aftertreatment system provides a NO x -reduction chemical storage device, and determining a NO x -Increase in quantity in response to an impending NO x -Reduction chemical release from the NO x -reduction chemical storage device. In certain embodiments, the method further comprises increasing the NO x based on the NO x-increase amount. In certain embodiments, the method further comprises determining the impending NO x -reduction chemical release by determining that a load value for the engine has increased above a threshold. In certain further embodiments, the method includes determining the impending NO x -Reduction chemical release by detecting that a temperature value for the catalyst has risen above a threshold.

[0032] In certain embodiments, the method includes determining whether the NO x -reduction chemical storage device a stored amount of NO x -reduction chemical, whereby the NO x -reduction chemical storage device comprises at least one catalyst and / or an exhaust pipe. In certain embodiments, determining whether the NO x-reduction chemical storage device a stored amount of NO x -reduction chemical, determine whether the NO x -reduction chemical storage device has a time duration threshold at a temperature below a NO x reduction chemical storage temperature threshold. In certain embodiments, determining whether the NO x -reduction chemical storage device a stored amount of NO x -reduction chemical, further integrating an unreacted NO x -reduction chemical amount over a period of time. In certain embodiments, increasing a NO x -emissions from an engine, reducing an exhaust gas recirculation rate, advancing a fuel injection timing value and / or increasing an intake manifold temperature value.

[0033] One embodiment is a method comprising determining whether an ammonia storage device contains a stored amount of ammonia, predicting an impending ammonia release from the ammonia storage device, determining a NO x -Increase in response to the impending ammonia release and an increase in NO supplied by an engine x -Amount based on the NO x -increase amount. In certain embodiments, determining the NO x -increase in response to the impending ammonia release, setting a NO x -increase schedule based on the amount of ammonia stored. In certain embodiments, the NO x -rise plan a fixed NO x -Rise time duration, and in certain further embodiments, the method further comprises decrementing the specified NO x-Rise time based on an estimated catalyst aging value.

[0034] In certain embodiments, predicting an impending ammonia release from the ammonia storage device comprises determining whether a temperature rise rate of the ammonia storage device exceeds a temperature rise rate threshold. In certain embodiments, predicting an impending ammonia release from the ammonia storage device comprises determining whether an engine load rise rate exceeds an engine load rise rate threshold. In certain embodiments, increasing a NO supplied by an engine comprises x -Amount, decreasing an exhaust gas recirculation rate, advancing a fuel injection timing value, and / or increasing an intake manifold temperature value. In certain embodiments, increasing an NOx -Amount increasing a fuel rail pressure, adjusting a post fuel injection event, adjusting a variable valve timing, increasing a boost pressure, adjusting a pre fuel injection event and / or adjusting an air / fuel ratio for the engine.

[0035] An exemplary embodiment is a system having an internal combustion engine producing an exhaust stream including a NO x-amount, an ammonia introduction device configured to introduce ammonia or an ammonia precursor into the exhaust stream, an ammonia storage device that stores ammonia during at least a portion of engine operation, and a controller configured to perform operations. In certain embodiments, the operations include an operation to determine whether an ammonia storage device contains a stored amount of ammonia, an operation to predict an impending ammonia release from the ammonia storage device, an operation to determine a NO x -increase in response to the impending ammonia release, and an operation to increase a NO supplied by an engine x -Amount based on the NO x -Increase in quantity.

[0036] In certain embodiments, the internal combustion engine includes a system for implementing variable valve timing (VVT), and the controller is further configured to perform an operation for increasing the NO x -amount by controlling the VVT ​​system to increase an effective compression ratio or controlling the VVT ​​system to reduce a combustion residue in a combustion cylinder of the internal combustion engine. In certain embodiments, the internal combustion engine includes a turbocharger and an intercooler, and the control unit is further configured to perform an operation to increase the NO supplied by the engine. x-Amount by controlling an actuator configured to reduce a heat exchange rate of the charge air cooler. In certain embodiments, the internal combustion engine includes a first turbocharger and a second turbocharger, and the controller is further configured to perform an operation to increase the NO supplied by the engine. x -Amount by controlling the first turbocharger and the second turbocharger in the sense of a redistribution of compression loads in such a way that an intake manifold temperature is increased.

[0037] In certain embodiments, the internal combustion engine includes a common rail fuel system and the controller is further configured to perform an operation to increase the NO x-amount by instructing the common rail fuel system to increase a fuel rail pressure. In certain embodiments, the internal combustion engine includes a common rail fuel system, and the controller is further configured to perform an operation to increase the NO x -amount by instructing the common rail fuel system to influence a fuel post-injection operation. In certain embodiments, the internal combustion engine includes a common rail fuel system, and the controller is further configured to perform an operation to increase the NO x -amount by instructing the common rail fuel system to influence a fuel pre-injection event.

[0038] In certain embodiments, the internal combustion engine includes a variable geometry turbocharger, and the controller is further configured to perform an operation to increase the NO x -Amount by commanding the variable geometry turbocharger to increase boost pressure. In certain embodiments, the system further includes an exhaust gas recirculation (EGR) flow and an EGR valve, and the controller is further configured to perform an operation to increase the delivered NO x -Amount by reducing the exhaust gas recirculation flow rate.

[0039] An exemplary embodiment is a device comprising a reductant storage module configured to determine whether a reductant storage device contains a stored amount of the reductant, a reductant release prediction module configured to determine an impending reductant release, a NO x -Slope setting module designed to provide a NO x -increase in response to the stored amount of reducing agent and the impending release of reducing agent, and a NO x -Rise control module designed to control an NO supplied by an engine x -Amount in response to NO x -increase amount. In certain embodiments, the apparatus further comprises a catalyst reaction rate module configured to determine an unreacted reductant amount, and the NO x-Rise setting module is also designed to determine the NO x -increase amount in response to the unreacted reductant amount. In certain embodiments, the apparatus further comprises a catalyst aging estimation module configured to determine a catalyst aging value, and the catalyst reaction rate module is further configured to determine the unreacted reductant amount in response to the catalyst aging value.

[0040] In certain embodiments, the reductant release prediction module is further configured to determine the impending reductant release in response to at least one of an engine load value and a catalyst temperature value. In certain embodiments, the reductant release prediction module is further configured to determine the impending reductant release in response to at least one of a time derivative of an engine load value and a time derivative of a catalyst temperature value.

[0041] Yet another exemplary embodiment is a method comprising operating an engine with an aftertreatment system, wherein the aftertreatment system comprises a NO x -reduction chemical storage facility, and, in response to an impending NO x -Reduction chemical release from the NO x-reduction chemical storage device, performing an NH3 slip mitigation operation. In a further embodiment, the NH3 slip mitigation operation comprises determining a NO x -Increase in quantity and increase in the NO supplied by the engine x based on the NO x -increase amount. In an alternative or additional embodiment, the NH3 slip mitigation operation comprises determining the impending NO x -Reduction chemical release by determining that a NO x-reduction chemical storage device exceeds a release threshold, and determining that an engine operating demand produces a nominal exhaust temperature higher than an NH3 release temperature, and reducing an engine torque value such that the nominal exhaust temperature is shifted below the NH3 release temperature. The nominal exhaust temperature comprises an estimated exhaust temperature and / or a measured exhaust temperature.

[0042] Although the invention has been particularly illustrated and described in the figures and the foregoing description, it is to be considered as illustrative and not restrictive, and it is to be understood that only certain exemplary embodiments have been shown and described, and that all changes and modifications which come within the spirit of the invention are intended to be protected. It should be understood that although the use of words such as preferred, preferable, advantageous, or more advantageous in the above description indicates that the feature so identified may be more desirable, it may not be necessary, and embodiments without that feature are contemplated as being within the scope of the invention, which scope is defined by the following claims.When reading the claims, the use of words such as "a," "an," "at least one," or "at least one section" is not intended to limit the claim to only one element unless explicitly stated otherwise in the claim. When the phrase "at least one section" and / or "a section" is used, the subject matter may encompass part and / or all of the subject matter unless explicitly stated otherwise.

Claims

[1] Method comprising: Operating (502) an engine (104) with an aftertreatment system, wherein the aftertreatment system comprises a NO x -reduction chemical storage device (112), Performing an NH3 slip mitigation operation (506) in response to an impending NO x -Reduction chemical release from the NO x -reduction chemical storage device (112); the method further comprising: a determination (504) of the impending NO x -Reduction chemical release by determining (514) that a NO x-reduction chemical storage device (112) stored-NH3 amount exceeds a release threshold, and by determining (516) that an engine operating demand produces a nominal exhaust gas temperature that is higher than an NH3 release temperature, the method further comprising decreasing (518) an engine torque value such that the nominal exhaust gas temperature is shifted below the NH3 release temperature. [2] The method of claim 1, wherein the NH3 slip mitigation operation (506) comprises determining (510) a NO x -increase amount and an increase (512) of the NO supplied by the engine (104) x based on the NO x -increase amount includes. [3] The method of claim 1, wherein the nominal exhaust gas temperature comprises an estimated exhaust gas temperature or a measured exhaust gas temperature.

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