US20140331644A1

US20140331644A1 - Exhaust aftertreatment component condition estimation and regeneration

Info

Publication number: US20140331644A1
Application number: US13/890,123
Authority: US
Inventors: Shankar Kumar; Krishna Kamasamudram
Original assignee: Cummins Intellectual Property Inc
Current assignee: Cummins Intellectual Property Inc
Priority date: 2013-05-08
Filing date: 2013-05-08
Publication date: 2014-11-13

Abstract

Described herein is an apparatus for an exhaust aftertreatment system includes a first aftertreatment component poison module that is configured to generate a first component poison regeneration request based on an estimated accumulation of a first poison on the first aftertreatment component. The accumulation of the first poison on the first aftertreatment component is based on an estimated amount of the first poison being released from the first aftertreatment component. The apparatus also includes a second aftertreatment component poison module that is configured to generate a second component poison regeneration request based on an estimated accumulation of the first poison on the second aftertreatment component. The accumulation of the first poison on the second aftertreatment component is based on the estimated amount of the first poison being released from the first aftertreatment component.

Description

FIELD

This disclosure relates generally to internal combustion engine systems, and more particularly to estimating the accumulation of species on components of an exhaust aftertreatment system and regenerating the components of the exhaust aftertreatment system to remove the accumulation of species.

BACKGROUND

Emissions regulations for internal combustion engines have become more stringent over recent years. Environmental concerns have motivated the implementation of stricter emission requirements for internal combustion engines throughout much of the world. Governmental agencies, such as the Environmental Protection Agency (EPA) in the United States, carefully monitor the emission quality of engines and set acceptable emission standards, to which all engines must comply. Consequently, the use of exhaust aftertreatment systems on engines to reduce emissions is increasing.
Generally, emission requirements vary according to engine type. Emission tests for compression-ignition (diesel) engines typically monitor the release of carbon monoxide (CO), unburned hydrocarbons (UHC), diesel particulate matter (PM) such as ash and soot, and nitrogen oxides (NOx). Oxidation catalysts, such as diesel oxidation catalysts (DOC) have been implemented in exhaust gas aftertreatment systems to oxidize at least some particulate matter in the exhaust stream, reduce unburned hydrocarbons and CO in the exhaust to less environmentally harmful compounds, and oxidize nitric oxide (NO) to form nitrogen dioxide (NO₂), which is used in the NOx conversion on an selective catalytic reduction (SCR) catalyst. To remove the particulate matter, a particulate matter (PM) filter is typically installed downstream from the oxidation catalyst or in conjunction with the oxidation catalyst. However, some exhaust aftertreatment systems do not have a PM filter. With regard to reducing NOx emissions, NOx reduction catalysts, including SCR systems, are utilized to convert NOx (NO and NO₂in some fraction) to N₂and other compounds. Further, some systems include an ammonia oxidation (AMOX) catalyst downstream of the SCR catalyst to convert at least some ammonia slipping from the SCR catalyst to N₂and other less harmful compounds.
Exhaust aftertreatment system components can be susceptible to the accumulation of various materials on the components. In most cases, such material accumulations or deposits negatively affect the operation, performance, or efficiency of the components. Accordingly, the materials that accumulate on aftertreatment components and negatively affect the functionality of the components can be considered poisons. Several poisonous materials include sulfur, unburned hydrocarbons (HC), and water. For example, accumulations or deposits of sulfur-containing species on the DOC tends to decrease the conversion of NO to NO₂, decrease the conversion of HC to CO₂and heat, which affects the thermal management of an engine system, and increase the presence or accumulation of HC in the DOC, which correspondingly decreases the conversion of NO to NO₂. Additionally, the presence of sulfur deposits on the SCR catalyst decreases the NOx-conversion capability of the SCR catalyst, and the presence of sulfur deposits on the AMOX catalyst decreases the ammonia-conversion capability of the AMOX catalyst.
The accumulation of HC species and water on the DOC, SCR catalyst, and AMOX catalyst can cause similar negative effects on the functionality of these components. Additionally, accumulation of HC species on the DOC in the presence of an increase in the temperature of the DOC may cause uncontrolled light-off events or runaway regeneration. Such light-off events may damage the DOC and send damaging sintered elements of the DOC into the SCR catalyst and AMOX catalyst.
Because of the negative side-effects of sulfur, HC, and water species accumulation on aftertreatment components, conventional exhaust aftertreatment systems conduct a periodic regeneration of the components to remove the accumulated species. Most periodic regeneration events are initiated based on the passing of a preset period of time or a predetermined amount of fuel consumed by the engine regardless of the amount of accumulated poisonous species on the various components of the exhaust aftertreatment system.

SUMMARY

The subject matter of the present application has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available exhaust aftertreatment systems. Accordingly, the subject matter of the present application has been developed to provide methods, systems, and apparatus for estimating conditions of components of an exhaust aftertreatment system, and regenerating the system based on the estimated conditions. Generally, according to one embodiment, disclosed herein is an improved method, system, and apparatus for individually and separately estimating the accumulation of a poisonous species (e.g., sulfur, HC, and/or water) on multiple components of an exhaust aftertreatment system, and regenerating the multiple components of the system based on an estimated species accumulation of a single component reaching a predetermined threshold.
According to one embodiment, an apparatus for an exhaust aftertreatment system includes a first aftertreatment component poison module that is configured to generate a first component poison regeneration request based on an estimated accumulation of a first poison on the first aftertreatment component. The accumulation of the first poison on the first aftertreatment component is based on an estimated amount of the first poison being released from the first aftertreatment component. The apparatus also includes a second aftertreatment component poison module that is configured to generate a second component poison regeneration request based on an estimated accumulation of the first poison on the second aftertreatment component. The accumulation of the first poison on the second aftertreatment component is based on the estimated amount of the first poison being released from the first aftertreatment component.
According to some implementations, the apparatus also includes a poison regeneration arbitration module that is configured to generate a poison regeneration command based on an arbitration of the first and second component poison regeneration requests. The apparatus can also include a time-based regeneration module that is configured to generate a system regeneration request based on the passage of a preset period of time. The first poison regeneration arbitration module can be configured to generate the poison regeneration command based on an arbitration of the first component poison regeneration request, second component poison regeneration request, and system regeneration request.
In some implementations of the apparatus, the accumulation of the first poison on the second aftertreatment component is based on an estimated amount of the first poison being released from the second aftertreatment component. The apparatus can further include a third aftertreatment component poison module that is configured to generate a third component poison regeneration request based on an estimated accumulation of the first poison on the third aftertreatment component. The accumulation of the first poison on the third aftertreatment component being can be based on the estimated amount of the first poison being released from the second aftertreatment component.
According to certain implementations of the apparatus, the first aftertreatment component poison module is configured to estimate an amount of the first poison being stored on the first aftertreatment component. The accumulation of the first poison on the first aftertreatment component can be based on a difference between the amount of the first poison being stored on the first aftertreatment component and the amount of the first poison being released from the first aftertreatment component. The second aftertreatment component poison module can be configured to estimate an amount of the first poison being stored on the second aftertreatment component. The accumulation of the first poison on the second aftertreatment component can be based on a difference between the amount of the first poison being stored on the second aftertreatment component and the amount of the first poison being released from the second aftertreatment component. The amount of the first poison being stored on the first aftertreatment component can be estimated based on a temperature of the first aftertreatment component and a mass flow rate of exhaust gas into the first aftertreatment component. The amount of the first poison being stored on the second aftertreatment component can be estimated based on a temperature of the second aftertreatment component and a mass flow rate of exhaust gas into the second aftertreatment component. The amount of the first poison being released from the first aftertreatment component can be estimated based on the temperature of the first aftertreatment component and the amount of the first poison being stored on the first aftertreatment component. The amount of the first poison being released from the second aftertreatment component can be estimated based on the temperature of the second aftertreatment component and the amount of the first poison being stored on the second aftertreatment component.
In some implementations of the apparatus, the first component poison regeneration request includes first regeneration event parameters, and the second component poison regeneration request includes second regeneration event parameters. The first regeneration event parameters can be different than the second regeneration event parameters. The first poison can be one of sulfur, hydrocarbon, or water. The first aftertreatment component can include one of a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction catalyst, or an ammonia oxidation catalyst, and the second aftertreatment component can include another one of the diesel oxidation catalyst, diesel particulate filter, selective catalytic reduction catalyst, or ammonia oxidation catalyst.
According to some implementations, the apparatus additionally includes a third aftertreatment component poison module that is configured to generate a third component poison regeneration request based on an estimated accumulation of a second poison on the first aftertreatment component. The accumulation of the second poison on the first aftertreatment component can be based on an amount of the second poison being released from the first aftertreatment component. The apparatus may also include
a fourth aftertreatment component poison module that is configured to generate a fourth component poison regeneration request based on an estimated accumulation of the second poison on the second aftertreatment component. The accumulation of the second poison on the second aftertreatment component being can be based on the estimated amount of the second poison being released from the first aftertreatment component. The poison regeneration arbitration module may be configured to generate the poison regeneration command based on an arbitration of the first, second, third, and fourth component poison regeneration requests.
In some implementations, the first aftertreatment component poison module generates the first component poison regeneration request when the estimated accumulation of the first poison on the first aftertreatment component meets a first poison accumulation threshold. The first poison accumulation threshold can correspond with a minimum allowable performance characteristic of the first aftertreatment component. The second aftertreatment component poison module can generate the second component poison regeneration request when the estimated accumulation of the first poison on the second aftertreatment component meets a second poison accumulation threshold. The second poison accumulation threshold can correspond with a minimum allowable performance characteristic of the second aftertreatment component. The first poison accumulation threshold can be different than the second poison accumulation threshold. According to certain implementations, the first aftertreatment component includes one of a diesel oxidation catalyst, a selective catalytic reduction catalyst, or an ammonia oxidation catalyst, and the minimum allowable performance characteristic of the first aftertreatment component includes one of a minimum allowable NO to NO₂oxidation efficiency, a minimum allowable NOx conversion efficiency, or a minimum allowable ammonia oxidation efficiency, respectively. According to yet certain implementations, the second aftertreatment component includes another one of the diesel oxidation catalyst, selective catalytic reduction catalyst, or ammonia oxidation catalyst, and the minimum allowable performance characteristic of the second aftertreatment component includes one of the minimum allowable NO to NO₂oxidation efficiency, minimum allowable NOx conversion efficiency, or minimum allowable ammonia oxidation efficiency, respectively.
In some implementations of the apparatus, the first poison includes hydrocarbon. At least the first aftertreatment component poison module can include an exothermal module configured to monitor an exothermal condition of the first aftertreatment component. The first aftertreatment component poison module generates an exothermal regeneration request when the exothermal condition meets an exothermal condition threshold.
According to another embodiment, an exhaust aftertreatment system in exhaust gas receiving communication with an internal combustion engine includes a DOC, an SCR catalyst downstream of the DOC, and an AMOX catalyst downstream of the SCR catalyst. The system also includes a DOC poison module that is configured to estimate an accumulation of a first poison on the DOC, and configured to request regeneration of the DOC when the accumulation of the first poison on the DOC meets a first predetermined poison accumulation threshold corresponding with a minimum desirable NO to NO₂oxidation efficiency of the DOC. Additionally, the system includes an SCR poison module that is configured to estimate an accumulation of the first poison on the SCR catalyst, and configured to request regeneration of the SCR catalyst when the accumulation of the first poison on the SCR catalyst meets a second predetermined poison accumulation threshold corresponding with a minimum desirable NOx conversion efficiency of the SCR catalyst. Also, the system includes an AMOX poison module that is configured to estimate an accumulation of the first poison on the AMOX catalyst, and configured to request regeneration of the AMOX catalyst when the accumulation of the first poison on the AMOX catalyst meets a third predetermined poison accumulation threshold corresponding with a minimum desirable ammonia oxidation efficiency of the AMOX catalyst.
In some implementations of the system, the DOC poison module is further configured to estimate an amount of poison being released from the internal combustion engine and an amount of poison being released from the DOC. The estimate of the accumulation of the first poison on the DOC can be based on the amount of poison being released from the internal combustion engine. The SCR poison module can be further configured to estimate an amount of poison being released from the SCR catalyst. The estimate of the accumulation of the first poison on the SCR catalyst can be based on the amount of poison being released from the DOC. The estimate of the accumulation of the first poison on the AMOX catalyst can be based on the amount of poison being released from the SCR catalyst.
In yet another embodiment, a method for estimating conditions of and regenerating exhaust aftertreatment system components include estimating an accumulated quantity of a poison on a first aftertreatment component. The method also includes commanding a regeneration of the exhaust aftertreatment system if the accumulated quantity of the poison on the first aftertreatment component meets a first threshold associated with a performance characteristic of the first aftertreatment component. Further, the method includes estimating an accumulated quantity of the poison on a second aftertreatment component, and commanding a regeneration of the exhaust aftertreatment system if the accumulated quantity of the poison on the second aftertreatment component meets a second threshold associated with a performance characteristic of the second aftertreatment component.
In some implementations, the method includes determining an amount of the poison entering the first aftertreatment component. Estimating the accumulated quantity of the poison on the first aftertreatment component can be based on the amount of the poison entering the first aftertreatment component. The method may also include estimating an amount of poison being released from the first aftertreatment component. Estimating the accumulated quantity of the poison on the second aftertreatment component can be based on the amount of poison being released from the first aftertreatment component.
In certain embodiments, the modules of the apparatus described herein may each include at least one of logic hardware and executable code, the executable code being stored on one or more memory devices. The executable code may be replaced with a computer processor and computer-readable storage medium that stores executable code executed by the processor.
Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the subject matter of the present disclosure should be or are in any single embodiment. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.
The described features, structures, advantages, and/or characteristics of the subject matter of the present disclosure may be combined in any suitable manner in one or more embodiments and/or implementations. In the following description, numerous specific details are provided to impart a thorough understanding of embodiments of the subject matter of the present disclosure. One skilled in the relevant art will recognize that the subject matter of the present disclosure may be practiced without one or more of the specific features, details, components, materials, and/or methods of a particular embodiment or implementation. In other instances, additional features and advantages may be recognized in certain embodiments and/or implementations that may not be present in all embodiments or implementations. Further, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by the practice of the subject matter as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the subject matter may be more readily understood, a more particular description of the subject matter briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the subject matter and are not therefore to be considered to be limiting of its scope, the subject matter will be described and explained with additional specificity and detail through the use of the drawings, in which:

FIG. 1 is a schematic diagram of an engine system having an internal combustion engine and an exhaust aftertreatment system in accordance with one representative embodiment;

FIG. 2 is a schematic block diagram of a controller of the engine system of FIG. 1 in accordance with one representative embodiment;

FIG. 3 is a schematic block diagram of a sulfur oxidation module of the controller of FIG. 2 in accordance with one representative embodiment;

FIG. 4 is a schematic block diagram of a hydrocarbon oxidation module of the controller of FIG. 2 in accordance with one representative embodiment; and

FIG. 5 is a schematic flow chart diagram of a method for diagnosing a condition of an exhaust aftertreatment component and correspondingly regenerating the component in accordance with one representative embodiment.

DETAILED DESCRIPTION

FIG. 1 depicts one embodiment of an engine system 10. The main components of the engine system 10 include an internal combustion engine 20 and an exhaust aftertreatment system 22 in exhaust gas-receiving communication with the engine 20. The internal combustion engine 20 can be a compression-ignited internal combustion engine, such as a diesel-fueled engine, or a spark-ignited internal combustion engine, such as a gasoline-fueled engine operated lean. Although not shown, on the air intake side, the engine system 10 can include an air inlet, inlet piping, a turbocharger compressor, and an intake manifold. The intake manifold includes an outlet that is operatively coupled to compression chambers of the internal combustion engine 20 for introducing air into the compression chambers.
Within the internal combustion engine 20, air from the atmosphere is combined with fuel, and combusted, to power the engine. The fuel comes from a fuel tank (not shown) through a fuel delivery system including, in one embodiment, a fuel pump and common rail to the fuel injectors, which inject fuel into the combustion chambers of the engine 20. Fuel injection timing can be controlled by the controller 100 via a fuel injector control signal.
Combustion of the fuel and air in the compression chambers of the engine 20 produces exhaust gas that is operatively vented to an exhaust manifold (not shown). From the exhaust manifold, a portion of the exhaust gas may be used to power a turbocharger turbine. The turbocharger turbine drives the turbocharger compressor, which may compress at least some of the air entering the air inlet before directing it to the intake manifold and into the compression chambers of the engine 20.
The exhaust aftertreatment system 22 includes the controller 100 (which also can form part of the overall engine system 10), an optional diesel particular filter (DPF) 40, a diesel oxidation catalyst (DOC) 30, a selective catalytic reduction (SCR) system 52 with an SCR catalyst 50, and an ammonia oxidation (AMOX) catalyst 60. The SCR system 52 further includes a reductant delivery system that has a diesel exhaust fluid (DEF) source 54 that supplies DEF to a DEF doser 56 via a DEF or reductant delivery line 58.
In an exhaust flow direction, as indicated by directional arrow 29, exhaust gas flows from the engine 20 into inlet piping 24 of the exhaust aftertreatment system 22. From the inlet piping 24, the exhaust gas flows into the DOC 30 and exits the DOC into a first section of exhaust piping 28A. From the first section of exhaust piping 28A, the exhaust gas flows into the DPF 40 if present and exits the DPF into a second section of exhaust piping 28B. From the second section of exhaust piping 28B, the exhaust gas flows into the SCR catalyst 50 and exits the SCR catalyst into the third section of exhaust piping 28C. As the exhaust gas flows through the second section of exhaust piping 28B, it is periodically dosed with DEF by the DEF doser 56. Accordingly, the second section of exhaust piping 28B acts as a decomposition chamber or tube to facilitate the decomposition of the DEF to ammonia. From the third section of exhaust piping 28C, the exhaust gas flows into the AMOX catalyst 60 and exits the AMOX catalyst into outlet piping 26 before the exhaust gas is expelled from the system 22. Based on the foregoing, in the illustrated embodiment, the DOC 30 is position upstream of the DPF 40 if present and the SCR catalyst 50, and the SCR catalyst 50 is positioned downstream of the DPF 40 when present and upstream of the AMOX catalyst 60. However, in alternative embodiments, other arrangements of the components of the exhaust aftertreatment system 22 are also possible.
The DOC 30 can have any of various flow-through designs known in the art. Generally, the DOC 30 is configured to oxidize at least some particulate matter, e.g., the soluble organic fraction of soot, in the exhaust and reduce unburned hydrocarbons and CO in the exhaust to less environmentally harmful compounds. For example, the DOC 30 may sufficiently reduce the hydrocarbon and CO concentrations in the exhaust to meet the requisite emissions standards for those components of the exhaust gas. An indirect consequence of the oxidation capabilities of the DOC 30 is the ability of the DOC to oxidize NO into NO₂. In this manner, the level of NO₂exiting the DOC 30 is equal to the NO₂in the exhaust gas generated by the engine 20 plus the NO₂converted from NO by the DOC. Accordingly, one metric for indicating the condition of the DOC 30 is the NO₂/NOx ratio of the exhaust gas exiting the DOC.
In addition to treating the hydrocarbon and CO concentrations in the exhaust gas, the DOC 30 can also be used in the controlled regeneration of the DPF 40 when present, the SCR catalyst 50, and the AMOX catalyst 60. This can be accomplished through the injection, or dosing, of unburned HC into the exhaust gas upstream of the DOC 30. Upon contact with the DOC 30, the unburned HC undergoes an exothermic oxidation reaction which leads to an increase in the temperature of the exhaust gas exiting the DOC 30 and subsequently entering the DPF 40, SCR catalyst 50, and/or the AMOX catalyst 60. The amount of unburned HC added to the exhaust gas is selected to achieve the desired temperature increase or target controlled regeneration temperature.
When present, the DPF 40 can be any of various flow-through designs known in the art, and configured to reduce particulate matter concentrations, e.g., soot and ash, in the exhaust gas to meet requisite emission standards. According to certain applications, such as in emerging markets and developing countries, the exhaust aftertreatment system 22 does not include a DPF 40. Because such systems lack a DPF 40, particulate matter and other constituents normally captured by a DPF are passed and accumulate onto the SCR catalyst 50 and AMOX catalyst 60. Therefore, the need for a more precisely controlled and robust system for estimating the condition of components normally downstream of a DPF (e.g., the SCR catalyst 50 and AMOX catalyst 60) and regenerating those components when needed may be greater for systems without a DPF 40, than those systems with a DPF. Additionally, the DPF 40 when present may be configured to oxidize NO to form NO₂independent of the DOC 30.
As discussed above, the SCR system 52 includes a reductant delivery system with a reductant (e.g., DEF) source 54, pump (not shown) and delivery mechanism or doser 56. The reductant source 54 can be a container or tank capable of retaining a reductant, such as, for example, ammonia (NH₃), DEF (e.g., urea), or diesel oil. The reductant source 54 is in reductant supplying communication with the pump, which is configured to pump reductant from the reductant source to the delivery mechanism 56 via a reductant delivery line 58. The delivery mechanism 56 is positioned upstream of the SCR catalyst 50. The delivery mechanism 56 is selectively controllable to inject reductant directly into the exhaust gas stream prior to entering the SCR catalyst 50.
In some embodiments, the reductant can either be ammonia or DEF, which decomposes to produce ammonia. The ammonia reacts with NOx in the presence of the SCR catalyst 50 to reduce the NOx to less harmful emissions, such as N₂and H₂O. The NOx in the exhaust gas stream includes NO₂and NO. Generally, both NO₂and NO are reduced to N₂and H₂O through various chemical reactions driven by the catalytic elements of the SCR catalyst in the presence of NH₃. However, as discussed above, the chemical reduction of NO₂to N₂and H₂O typically is the most efficient chemical reaction. Therefore, in general, the more NO₂in the exhaust gas stream compared to NO, the more efficient the NO_xreduction performed by the SCR catalyst. Accordingly, the ability of the DOC 30 to convert NO to NO₂directly affects the NOx reduction efficiency of the SCR system 52. Put another way, the NOx reduction efficiency of the SCR system 52 corresponds at least indirectly to the condition or performance of the DOC 30. However, primarily, the NOx reduction efficiency of the SCR system 52 corresponds with the condition or performance of SCR catalyst 50.
The SCR catalyst 50 can be any of various catalysts known in the art. For example, in some implementations, the SCR catalyst 50 is a vanadium-based catalyst, and in other implementations, the SCR catalyst is a zeolite-based catalyst, such as a Cu-Zeolite or a Fe-Zeolite catalyst. In one representative embodiment, the reductant is aqueous urea and the SCR catalyst 50 is a zeolite-based catalyst.
The AMOX catalyst 60 can be any of various flow-through catalysts configured to react with ammonia to produce mainly nitrogen. Generally, the AMOX catalyst 60 is utilized to remove ammonia that has slipped through or exited the SCR catalyst 50 without reacting with NO_xin the exhaust. In certain instances, the aftertreatment system 22 can be operable with or without an AMOX catalyst. Further, although the AMOX catalyst 60 is shown as a separate unit from the SCR catalyst 50, in some implementations, the AMOX catalyst can be integrated with the SCR catalyst, e.g., the AMOX catalyst and the SCR catalyst can be located within the same housing. The condition of the AMOX catalyst 60 can be represented by the performance of the AMOX catalyst (i.e., the ability of the AMOX catalyst to convert ammonia into mainly nitrogen).
Various sensors, such as temperature sensors 12 and mass flow sensor 14, may be strategically disposed throughout the exhaust aftertreatment system 22 and may be in communication with the controller 100 to monitor operating conditions of the engine system 10. In one embodiment, the temperature sensors 12 sense the temperature of exhaust gas flowing through the exhaust aftertreatment system 22 at various locations, and the mass flow sensor 14 senses the rate at which the exhaust gas is flowing into and through the exhaust aftertreatment system. Although only temperature and mass flow sensors 12, 14 are shown, in other embodiments, the engine system 10 and exhaust aftertreatment system 22 may include more or fewer sensors than those shown.
Although the exhaust aftertreatment system 22 shown includes one of an DOC 30, an optional DPF 40, SCR catalyst 50, and AMOX catalyst 60 positioned in specific locations relative to each other along the exhaust flow path, in other embodiments, the exhaust aftertreatment system may include more than one of any of the various catalysts positioned in any of various positions relative to each other along the exhaust flow path as desired. Further, although the DOC 30 and AMOX catalyst 60 are non-selective catalysts, in some embodiments, the DOC and AMOX catalyst can be selective catalysts.
The controller 100 controls the operation of the engine system 10 and associated sub-systems, such as the internal combustion engine 20 and the exhaust gas aftertreatment system 22. The controller 100 is depicted in FIGS. 1 and 2 as a single physical unit, but can include two or more physically separated units or components in some embodiments if desired. Generally, the controller 100 receives multiple inputs, processes the inputs, and transmits multiple outputs. The multiple inputs may include sensed measurements, from the sensors, estimates from virtual sensors, and various user inputs. For example, referring to FIG. 2, operating conditions of the internal combustion engine 20 (e.g., engine condition inputs 102), conditions of the exhaust gas (e.g., exhaust condition inputs 104) flowing through the exhaust aftertreatment system 22, and time condition inputs 106 can be ascertained from any of the physical sensors, from any of various virtual sensors or models, user input, and/or via the controller's 100 commands to the engine, such as fuel rate, engine speed, engine load, and the like. The inputs are processed by the controller 100 using various algorithms, stored data, and other inputs to update the stored data and/or generate output values. The generated output values and/or commands are transmitted to other components of the controller and/or to one or more elements of the engine system 10 to control the system to achieve desired results, and more specifically, achieve desired exhaust gas emissions, and component performance and longevity.
Generally, the controller 100 includes various modules for controlling the operation of the engine system 10. For example, the controller 100 includes one or more modules for estimating conditions of the exhaust aftertreatment components 30, 40, 50, 60 and controlling the regeneration of the components. As is known in the art, the controller 100 and its various modular components may comprise processor, memory, and interface modules that may be fabricated of semiconductor gates on one or more semiconductor substrates. Each semiconductor substrate may be packaged in one or more semiconductor devices mounted on circuit cards. Connections between the modules may be through semiconductor metal layers, substrate-to-substrate wiring, or circuit card traces or wires connecting the semiconductor devices.
Referring to FIG. 2, the controller 100 includes a sulfur oxidation module 110 and a hydrocarbon oxidation module 120. Generally, the sulfur and hydrocarbon oxidation modules 110, 120 of the controller 100 receive inputs 102, 104, 106 and generate a sulfur regeneration command 112 and hydrocarbon regeneration command 122, respectively, based on at least one of the inputs. When generated, the commands 112, 122 communicate regeneration event parameters to the engine system 10. In response to the commands 112, 122, various components or levers of the engine system 10 are actuated to effectuate a regeneration event corresponding to the regeneration vent parameters of the commands. For example, the regeneration event parameters may include an exhaust temperature parameter, an exhaust mass flow rate parameter, and a timing parameter, the engine system 10 actuates internal or external fuel dosing components to increase the exhaust temperature and engine speed for a specified time in accordance with the parameters. Once commanded, the regeneration events can be effectuated using any of various techniques known in the art as desired.
As shown in FIG. 3, the sulfur oxidation module 110 includes a DOC sulfur module 130, an SCR sulfur module 150, an AMOX sulfur module 170, and a sulfur regeneration arbitration module 190. Each of the DOC sulfur, SCR sulfur, and AMOX sulfur modules 130, 150, 170 generate a respective sulfur regeneration request 140, 160, 180 if certain estimated conditions are met. The sulfur regeneration requests 140, 160, 180 are received by the sulfur regeneration arbitration module 190, which arbitrates between one or more sulfur regeneration requests, and a timer-based regeneration request, to generate the sulfur regeneration command 112. The sulfur regeneration command 112 then represents the characteristics of the winning regeneration request from the arbitration process.
The DOC sulfur module 130 of the sulfur oxidation module 110 includes a DOC sulfur storage module 132, DOC sulfur release module 134, DOC sulfur accumulation module 136, and DOC sulfur regeneration module 138. The DOC sulfur storage module 132 is configured to estimate the amount of sulfur being stored (e.g., adsorbed) on the DOC 30. As defined herein, sulfur can include any of various sulfur compounds, such as, for example, SOx (e.g., SO₂and SO₃), H₂SO₄, SOx on soot, and sulfates of ammonia and copper. According to the illustrated embodiment, the DOC sulfur storage module 132 estimates the amount or quantity of sulfur being stored on the DOC based on various inputs, such as, for example, the engine out sulfur (i.e., the quantity of sulfur in the exhaust gas exiting the engine 20 and entering the DOC 30), the temperature of the DOC, and the mass flow rate of exhaust gas into the DOC. In certain implementations, the engine out sulfur is a function of the fuel rate 124 (i.e., the rate of fuel entering and being consumed by the engine 20), and the fuel sulfur 126 (i.e., the concentration of sulfur in the fuel being consumed). Generally, the engine out sulfur can be expressed in terms of a volumetric or part-per-minute flow rate and is equal to a percentage of the fuel rate 124 multiplied by the fuel sulfur 126. The temperature of the DOC 30 (e.g., the catalyst bed of the DOC) can be determined by the DOC sulfur storage module 132 according to any of various techniques, such as using estimation modules and/or physical sensors. For example, the temperature of the DOC 30 can be determined based on the difference between exhaust gas temperature measurements taken by the temperature sensors 12 upstream and downstream of the DOC. Additionally, or alternatively, the exhaust aftertreatment system 22 may have a DOC mid-bed temperature sensor that more directly detects the temperature of the DOC 30.
According to one embodiment, the quantity of sulfur being stored on the DOC 30, which can be expressed as the rate of sulfur being stored on the DOC, for a given engine out sulfur value, can be obtained from a look-up table that is stored on the DOC sulfur storage module 132 and includes predetermined sulfur storage rates on the DOC 30 compared to DOC temperature values and exhaust mass flow rate values. The DOC sulfur storage module 132 can include a plurality of look-up tables each associated with a given engine out sulfur value. Accordingly, once the temperature of the DOC 30 and exhaust mass flow rate is determined or known, the sulfur storage rate on the DOC estimated by the DOC sulfur storage module 132 is the predetermined value in the look-up table (associated with the determined engine out sulfur value) for the determined DOC temperature and exhaust flow rate values. Generally, the sulfur adsorption rate on components is lower at higher exhaust gas temperatures. For engine out sulfur values between or outside those corresponding with the look-up tables, interpolation or extrapolation techniques can be utilized to estimate the DOC sulfur storage rate.
The quantity of sulfur stored on the DOC 30 over a desired time period, which can be represented by the time input 192, is then estimated by the DOC sulfur storage module 132 by multiplying the estimated DOC sulfur storage rate by the desired time period. In certain implementations, the quantity of sulfur stored on the DOC over the desired time period represents an estimate of the newly stored sulfur, which can be added to a previous estimate of the accumulation of sulfur on the DOC 30, as will be explained in more detail below, to obtain a more accurate estimate of the quantity of sulfur currently stored on the DOC.
The DOC sulfur release module 134 of the DOC sulfur module 130 is configured to estimate the DOC outlet sulfur 142 (i.e., the amount or quantity of sulfur being released (e.g., desorbed) from the DOC 30) based on various inputs, such as, for example, the temperature of the DOC and the quantity of sulfur stored on the DOC. Generally, the sulfur release rate from components is lower at higher exhaust gas temperatures. The DOC sulfur release module 134 may estimate the temperature of the DOC 30 in the same or similar manner as the DOC sulfur storage module 132, or simply utilize the temperature of the DOC estimated by the DOC sulfur storage module. Similarly, the quantity of sulfur stored on the DOC 30 can be obtained from the DOC sulfur storage module 132 or can be based on a previous estimate of the accumulation of sulfur on the DOC.
According to one embodiment, the DOC outlet sulfur 142 or amount of sulfur being released from the DOC 30, which can be expressed as the rate of sulfur being released from the DOC, can be obtained from a look-up table that is stored on the DOC sulfur release module 134 and includes predetermined sulfur release rates from the DOC 30 compared to DOC temperature values and DOC sulfur storage values. The DOC sulfur release module 134 can include a plurality of look-up tables each associated with a given DOC outlet sulfur value. Accordingly, once the temperature of the DOC 30 and DOC outlet sulfur value is determined or known, the sulfur release rate from the DOC estimated by the DOC sulfur release module 134 is the predetermined value in the look-up table for the determined DOC temperature and DOC sulfur storage values. The quantity of sulfur released from the DOC 30 over a desired time period (e.g., the same desired time period used by the DOC sulfur storage module 132 to estimate the DOC sulfur storage), which also can be represented by the time input 192, is then estimated by the DOC sulfur release module 134 by multiplying the estimated DOC sulfur release rate by the desired time period.
The quantity of sulfur stored on the DOC 30 estimated by the DOC sulfur storage module 132 and the DOC outlet sulfur 142 (or quantity of sulfur released from the DOC) estimated by the DOC sulfur release module 134 is used by the DOC sulfur accumulation module 136 to estimate a total accumulation of sulfur on the DOC 30. The DOC sulfur accumulation module 136 estimates the total accumulation of sulfur on the DOC 30 based on a difference between the estimated quantity of sulfur stored on the DOC 30 and the estimated quantity of sulfur released from the DOC. In one implementation, the DOC sulfur accumulation module 136 sets the total accumulation of sulfur on the DOC 30 equal to the difference between the estimated quantity of sulfur stored on the DOC 30 and the estimated quantity of sulfur released from the DOC.
The DOC sulfur regeneration module 138 generates a DOC sulfur regeneration request 140 based on a comparison between the total accumulation of sulfur on the DOC 30 estimated by the DOC sulfur accumulation module 136 and a DOC sulfur accumulation threshold. In one embodiment, the DOC sulfur regeneration module 138 generates a DOC sulfur regeneration request 140 only when the total accumulation of sulfur on the DOC 30 estimated by the DOC sulfur accumulation module 136 meets (e.g., is equal to or exceeds) the DOC sulfur accumulation threshold. In such an embodiment, should the total accumulation of sulfur on the DOC 30 estimated by the DOC sulfur accumulation module 136 not meet the DOC sulfur accumulation threshold, then a DOC sulfur regeneration request 140 is not generated. The DOC sulfur regeneration request 140 represents a demand to regenerate the DOC 30 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The operating parameters of the DOC regeneration event demanded by the DOC sulfur regeneration request 140 may vary based on any of various factors, such as, for example, the total accumulation of sulfur on the DOC 30, the period of time since the last DOC regeneration event, and the like. In some implementations, the sulfur regeneration request 140 is generated even if the total accumulation of sulfur on the DOC 30 does not meet the DOC sulfur accumulation threshold. However, in such implementations, the request 140 may be void of regeneration event parameters, such that the request effectively does not demand a regeneration event.
The DOC sulfur accumulation threshold corresponds with a DOC performance threshold. Like described above, the accumulation of sulfur on the DOC 30 may have a proportionally negative effect on the performance of the DOC. For example, the greater the accumulation of sulfur on the DOC 30, the lower the oxidation rate of CO to CO₂and the lower the oxidation of NO to NO₂. Accordingly, the DOC sulfur accumulation threshold can be predetermined to correspond with a minimum allowable performance characteristic, such as a minimum allowable CO to CO₂oxidation rate or efficiency and/or minimum allowable NO to NO₂oxidation rate or efficiency. As defined herein, allowable may mean desirable. In this manner, the DOC sulfur regeneration module 138 is configured to demand a DOC regeneration event by generating the DOC sulfur regeneration request 140 before the performance of the DOC 30 drops below the minimum allowable performance characteristic.
Before a DOC regeneration event according to the DOC sulfur regeneration request 140 is initiated, the DOC sulfur regeneration request 140 is received by the sulfur regeneration arbitration module 190, which determines whether the DOC sulfur regeneration request has priority over other possible regeneration requests, as will be described in more detail below. If the sulfur regeneration arbitration module 190 determines that the DOC sulfur regeneration request 140 has priority, then the sulfur regeneration arbitration module generates a sulfur regeneration command 112 that corresponds with the regeneration event parameters demanded by the DOC sulfur regeneration request.
The SCR sulfur module 150 of the sulfur oxidation module 110 is configured in a manner analogous to the DOC sulfur module 130 except the SCR sulfur module applies to the SCR catalyst 50 instead of the DOC 30. For example, the SCR sulfur module 150 includes an SCR sulfur storage module 152, SCR sulfur release module 154, SCR sulfur accumulation module 156, and SCR sulfur regeneration module 158. The SCR sulfur storage module 152 is configured to estimate the amount of sulfur being stored on the SCR catalyst 50. According to the illustrated embodiment, the SCR sulfur storage module 152 estimates the amount or quantity of sulfur being stored on the SCR based on various inputs, such as, for example, the DOC outlet sulfur 142 estimated by the DOC sulfur release module 134 (i.e., the quantity of sulfur in the exhaust gas exiting the DOC 30 and entering the SCR catalyst 50), the temperature of the SCR catalyst 50, and the mass flow rate of exhaust gas into the SCR catalyst. The temperature of the SCR catalyst 50 (e.g., the catalyst bed of the SCR catalyst) can be determined by the SCR sulfur storage module 152 according to any of various techniques, such as using estimation modules and/or physical sensors. For example, the temperature of the SCR catalyst 50 can be determined based on the difference between exhaust gas temperature measurements taken by the temperature sensors 12 upstream and downstream of the SCR catalyst 50. Additionally, or alternatively, the exhaust aftertreatment system 22 may have an SCR catalyst mid-bed temperature sensor that more directly detects the temperature of the SCR catalyst 50.
According to one embodiment, the quantity of sulfur being stored on the SCR catalyst 50, which can be expressed as the rate of sulfur being stored on the SCR catalyst 50, for a given DOC outlet sulfur value 142, can be obtained from a look-up table that is stored on the SCR sulfur storage module 152 and includes predetermined sulfur storage rates on the SCR catalyst 50 compared to SCR catalyst temperature values and exhaust mass flow rate values. The SCR sulfur storage module 152 can include a plurality of look-up tables each associated with a given DOC outlet sulfur value 142. Accordingly, once the temperature of the SCR catalyst 50 and exhaust mass flow rate is determined or known, the sulfur storage rate on the SCR catalyst estimated by the SCR sulfur storage module 152 is the predetermined value in the look-up table (associated with the determined DOC outlet sulfur value 142) for the determined SCR catalyst temperature and exhaust flow rate values. For DOC outlet sulfur values 142 between or outside those corresponding with the look-up tables, interpolation or extrapolation techniques can be utilized to estimate the SCR sulfur storage rate.
The quantity of sulfur stored on the SCR catalyst 50 over a desired time period, which can be represented by the time input 192, is then estimated by the SCR sulfur storage module 152 by multiplying the estimated SCR sulfur storage rate by the desired time period. In certain implementations, the quantity of sulfur stored on the SCR catalyst 50 over the desired time period represents an estimate of the newly stored sulfur on the SCR catalyst, which can be added to a previous estimate of the accumulation of sulfur on the SCR catalyst, as will be explained in more detail below, to obtain a more accurate estimate of the quantity of sulfur currently stored on the SCR catalyst.
The SCR sulfur release module 154 of the SCR sulfur module 150 is configured to estimate the SCR outlet sulfur 162 (i.e., the amount or quantity of sulfur being released from the SCR catalyst 50) based on various inputs, such as, for example, the temperature of the SCR catalyst and the quantity of sulfur stored on the SCR catalyst. The SCR sulfur release module 154 may estimate the temperature of the SCR catalyst 50 in the same or similar manner as the SCR sulfur storage module 152, or simply utilize the temperature of the SCR catalyst estimated by the SCR sulfur storage module. Similarly, the quantity of sulfur stored on the SCR catalyst 50 can be obtained from the SCR sulfur storage module 152 or can be based on a previous estimate of the accumulation of sulfur on the SCR catalyst.
According to one embodiment, the SCR outlet sulfur 162 or amount of sulfur being released from the SCR catalyst 50, which can be expressed as the rate of sulfur being released from the SCR catalyst, can be obtained from a look-up table that is stored on the SCR sulfur release module 154 and includes predetermined sulfur release rates from the SCR catalyst 50 compared to SCR catalyst temperature values and SCR catalyst sulfur storage values. The SCR sulfur release module 154 can include a plurality of look-up tables each associated with a given SCR outlet sulfur value 162. Accordingly, once the temperature of the SCR catalyst 50 and SCR outlet sulfur value 162 is determined or known, the sulfur release rate from the SCR catalyst 50 estimated by the SCR sulfur release module 154 is the predetermined value in the look-up table for the determined SCR temperature and SCR sulfur storage values. The quantity of sulfur released from the SCR catalyst 50 over a desired time period (e.g., the same desired time period used by the SCR sulfur storage module 152 to estimate the SCR sulfur storage), which also can be represented by the time input 192, is then estimated by the SCR sulfur release module 154 by multiplying the estimated SCR sulfur release rate by the desired time period.
The quantity of sulfur stored on the SCR catalyst 50 estimated by the SCR sulfur storage module 152 and the SCR outlet sulfur 162 (or quantity of sulfur released from the SCR catalyst) estimated by the SCR sulfur release module 154 is used by the SCR sulfur accumulation module 156 to estimate a total accumulation of sulfur on the SCR catalyst 50. The SCR sulfur accumulation module 156 estimates the total accumulation of sulfur on the SCR catalyst 50 based on a difference between the estimated quantity of sulfur stored on the SCR catalyst 50 and the estimated quantity of sulfur released from the SCR catalyst. In one implementation, the SCR sulfur accumulation module 156 sets the total accumulation of sulfur on the SCR catalyst 50 equal to the difference between the estimated quantity of sulfur stored on the SCR catalyst and the estimated quantity of sulfur released from the SCR catalyst.
The SCR sulfur regeneration module 158 generates an SCR sulfur regeneration request 160 based on a comparison between the total accumulation of sulfur on the SCR catalyst 50 estimated by the SCR sulfur accumulation module 156 and an SCR sulfur accumulation threshold. In one embodiment, the SCR sulfur regeneration module 158 generates an SCR sulfur regeneration request 160 only when the total accumulation of sulfur on the SCR catalyst 50 estimated by the SCR sulfur accumulation module 156 meets (e.g., is equal to or exceeds) the SCR sulfur accumulation threshold. In such an embodiment, should the total accumulation of sulfur on the SCR catalyst 50 estimated by the SCR sulfur accumulation module 156 not meet the SCR sulfur accumulation threshold, then an SCR sulfur regeneration request 160 is not generated. The SCR sulfur regeneration request 160 represents a demand to regenerate the SCR catalyst 50 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The operating parameters of the SCR catalyst regeneration event demanded by the SCR sulfur regeneration request 160 may vary based on any of various factors, such as, for example, the total accumulation of sulfur on the SCR catalyst 50, the period of time since the last SCR catalyst regeneration event, and the like. In some implementations, the sulfur regeneration request 160 is generated even if the total accumulation of sulfur on the SCR catalyst 50 does not meet the SCR sulfur accumulation threshold. However, in such implementations, the request 160 may be void of regeneration event parameters, such that the request effectively does not demand a regeneration event.
The SCR sulfur accumulation threshold corresponds with an SCR catalyst performance threshold. Like described above, the accumulation of sulfur on the SCR catalyst 50 may have a proportionally negative effect on the performance of the SCR catalyst. For example, the greater the accumulation of sulfur on the SCR catalyst 50, the lower the conversion rate of NOx in the presence of ammonia or the lower the NOx conversion efficiency. Accordingly, the SCR sulfur accumulation threshold can be predetermined to correspond with a minimum allowable performance characteristic, such as a minimum allowable NOx conversion rate or efficiency. In this manner, the SCR sulfur regeneration module 158 is configured to demand an SCR catalyst regeneration event by generating the SCR sulfur regeneration request 160 before the performance of the SCR catalyst 50 drops below the minimum allowable performance characteristic. Because the performance characteristics of the DOC 30 are different than those of the SCR catalyst 50, the respective sulfur accumulation thresholds can be different. For example, in certain implementations, the performance of the DOC 30 may better tolerate sulfur accumulations than the SCR catalyst 50. Accordingly, in such implementations, the sulfur accumulation threshold of the DOC 30 may be higher than that of the SCR catalyst 50. In AMOX other implementations, the sulfur accumulation threshold of the DOC 30 may be lower than that of the SCR catalyst 50.
Before an SCR catalyst regeneration event according to the SCR sulfur regeneration request 160 is initiated, the SCR sulfur regeneration request is received by the sulfur regeneration arbitration module 190, which determines whether the SCR sulfur regeneration request has priority over other possible regeneration requests, such as the DOC sulfur regeneration request 140 or other requests as will be described in more detail below. If the sulfur regeneration arbitration module 190 determines that the SCR sulfur regeneration request 160 has priority, then the sulfur regeneration arbitration module generates a sulfur regeneration command 112 that corresponds with the regeneration event parameters demanded by the SCR sulfur regeneration request.
The AMOX sulfur module 170 of the sulfur oxidation module 110 is configured in a manner analogous to the DOC and SCR sulfur modules 130, 150 except the AMOX sulfur module applies to the AMOX catalyst 60 instead of the DOC 30 and SCR catalyst 50. For example, the AMOX sulfur module 170 includes an AMOX sulfur storage module 172, AMOX sulfur release module 174, AMOX sulfur accumulation module 176, and AMOX sulfur regeneration module 178. The AMOX sulfur storage module 172 is configured to estimate the amount of sulfur being stored on the AMOX catalyst 60. According to the illustrated embodiment, the AMOX sulfur storage module 172 estimates the amount or quantity of sulfur being stored on the AMOX based on various inputs, such as, for example, the SCR outlet sulfur 162 estimated by the SCR sulfur release module 154 (i.e., the quantity of sulfur in the exhaust gas exiting the SCR catalyst 50 and entering the AMOX catalyst 60), the temperature of the AMOX catalyst 60, and the mass flow rate of exhaust gas into the AMOX catalyst. The temperature of the AMOX catalyst 60 (e.g., the catalyst bed of the AMOX catalyst) can be determined by the AMOX sulfur storage module 172 according to any of various techniques, such as using estimation modules and/or physical sensors. For example, the temperature of the AMOX catalyst 60 can be determined based on the difference between exhaust gas temperature measurements taken by the temperature sensors 12 upstream and downstream of the AMOX catalyst 60. Additionally, or alternatively, the exhaust aftertreatment system 22 may have an AMOX catalyst mid-bed temperature sensor that more directly detects the temperature of the AMOX catalyst 60.
According to one embodiment, the quantity of sulfur being stored on the AMOX catalyst 60, which can be expressed as the rate of sulfur being stored on the AMOX catalyst, for a given SCR outlet sulfur value 162, can be obtained from a look-up table that is stored on the AMOX sulfur storage module 172 and includes predetermined sulfur storage rates on the AMOX catalyst 60 compared to AMOX catalyst temperature values and exhaust mass flow rate values. The AMOX sulfur storage module 172 can include a plurality of look-up tables each associated with a given SCR outlet sulfur value 162. Accordingly, once the temperature of the AMOX catalyst 60 and exhaust mass flow rate is determined or known, the sulfur storage rate on the AMOX catalyst estimated by the AMOX sulfur storage module 172 is the predetermined value in the look-up table (associated with the determined SCR outlet sulfur value 162) for the determined AMOX catalyst temperature and exhaust flow rate values. For SCR outlet sulfur values 162 between or outside those corresponding with the look-up tables, interpolation or extrapolation techniques can be utilized to estimate the AMOX sulfur storage rate.
The quantity of sulfur stored on the AMOX catalyst 60 over a desired time period, which can be represented by the time input 192, is then estimated by the AMOX sulfur storage module 172 by multiplying the estimated AMOX sulfur storage rate by the desired time period. In certain implementations, the quantity of sulfur stored on the AMOX catalyst 60 over the desired time period represents an estimate of the newly stored sulfur on the AMOX catalyst, which can be added to a previous estimate of the accumulation of sulfur on the AMOX catalyst, as will be explained in more detail below, to obtain a more accurate estimate of the quantity of sulfur currently stored on the AMOX catalyst.
The AMOX sulfur release module 174 of the AMOX sulfur module 170 is configured to estimate the AMOX outlet sulfur 182 (i.e., the amount or quantity of sulfur being released from the AMOX catalyst 60) based on various inputs, such as, for example, the temperature of the AMOX catalyst and the quantity of sulfur stored on the AMOX catalyst. The AMOX sulfur release module 174 may estimate the temperature of the AMOX catalyst 60 in the same or similar manner as the AMOX sulfur storage module 172, or simply utilize the temperature of the AMOX catalyst estimated by the AMOX sulfur storage module. Similarly, the quantity of sulfur stored on the AMOX catalyst 60 can be obtained from the AMOX sulfur storage module 172 or can be based on a previous estimate of the accumulation of sulfur on the AMOX catalyst 60.
According to one embodiment, the AMOX outlet sulfur 182 or amount of sulfur being released from the AMOX catalyst 60, which can be expressed as the rate of sulfur being released from the AMOX catalyst, can be obtained from a look-up table that is stored on the AMOX sulfur release module 174 and includes predetermined sulfur release rates from the AMOX catalyst 60 compared to AMOX catalyst temperature values and AMOX catalyst sulfur storage values. The AMOX sulfur release module 174 can include a plurality of look-up tables each associated with a given AMOX outlet sulfur value 182. Accordingly, once the temperature of the AMOX catalyst 60 and AMOX outlet sulfur value 182 is determined or known, the sulfur release rate from the AMOX catalyst 60 estimated by the AMOX sulfur release module 174 is the predetermined value in the look-up table for the determined AMOX temperature and AMOX sulfur storage values. The quantity of sulfur released from the AMOX catalyst 60 over a desired time period (e.g., the same desired time period used by the AMOX sulfur storage module 172 to estimate the AMOX sulfur storage), which also can be represented by the time input 192, is then estimated by the AMOX sulfur release module 174 by multiplying the estimated AMOX sulfur release rate by the desired time period.
The quantity of sulfur stored on the AMOX catalyst 60 estimated by the AMOX sulfur storage module 172 and the AMOX outlet sulfur 182 (or quantity of sulfur released from the AMOX catalyst) estimated by the AMOX sulfur release module 174 is used by the AMOX sulfur accumulation module 176 to estimate a total accumulation of sulfur on the AMOX catalyst 60. The AMOX sulfur accumulation module 176 estimates the total accumulation of sulfur on the AMOX catalyst 60 based on a difference between the estimated quantity of sulfur stored on the AMOX catalyst 60 and the estimated quantity of sulfur released from the AMOX catalyst. In one implementation, the AMOX sulfur accumulation module 176 sets the total accumulation of sulfur on the AMOX catalyst 60 equal to the difference between the estimated quantity of sulfur stored on the AMOX catalyst and the estimated quantity of sulfur released from the AMOX catalyst.
The AMOX sulfur regeneration module 178 generates an AMOX sulfur regeneration request 180 based on a comparison between the total accumulation of sulfur on the AMOX catalyst 60 estimated by the AMOX sulfur accumulation module 176 and an AMOX sulfur accumulation threshold. In one embodiment, the AMOX sulfur regeneration module 178 generates an AMOX sulfur regeneration request 180 only when the total accumulation of sulfur on the AMOX catalyst 60 estimated by the AMOX sulfur accumulation module 176 meets (e.g., is equal to or exceeds) the AMOX sulfur accumulation threshold. In such an embodiment, should the total accumulation of sulfur on the AMOX catalyst 60 estimated by the AMOX sulfur accumulation module 176 not meet the AMOX sulfur accumulation threshold, then an AMOX sulfur regeneration request 180 is not generated. The AMOX sulfur regeneration request 180 represents a demand to regenerate the AMOX catalyst 60 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The operating parameters of the AMOX catalyst regeneration event demanded by the AMOX sulfur regeneration request 180 may vary based on any of various factors, such as, for example, the total accumulation of sulfur on the AMOX catalyst 60, the period of time since the last AMOX catalyst regeneration event, and the like. In some implementations, the sulfur regeneration request 180 is generated even if the total accumulation of sulfur on the AMOX catalyst 60 does not meet the AMOX sulfur accumulation threshold. However, in such implementations, the request 180 may be void of regeneration event parameters, such that the request effectively does not demand a regeneration event.
The AMOX sulfur accumulation threshold corresponds with an AMOX catalyst performance threshold. Like described above, the accumulation of sulfur on the AMOX catalyst 60 may have a proportionally negative effect on the performance of the AMOX catalyst. For example, the greater the accumulation of sulfur on the AMOX catalyst 60, the lower the conversion rate of ammonia or the lower the ammonia conversion efficiency. Accordingly, the AMOX sulfur accumulation threshold can be predetermined to correspond with a minimum allowable performance characteristic, such as a minimum allowable ammonia oxidation rate or efficiency. In this manner, the AMOX sulfur regeneration module 178 is configured to demand an AMOX catalyst regeneration event by generating the SCR sulfur regeneration request 180 before the performance of the AMOX catalyst 60 drops below the minimum allowable performance characteristic. Because the performance characteristics of the DOC 30 and SCR catalyst 50 are different than those of the AMOX catalyst 60, the respective sulfur accumulation thresholds can be different. For example, in certain implementations, the performance of the DOC 30 and/or SCR catalyst 50 may better tolerate sulfur accumulations than the AMOX catalyst 60. Accordingly, in such implementations, the sulfur accumulation thresholds of the DOC 30 and/or SCR catalyst 50 may be higher than that of the AMOX catalyst 60. In other implementations, the sulfur accumulation threshold of the DOC 30 and/or SCR catalyst 50 may be lower than that of the AMOX catalyst 60.
Before an AMOX catalyst regeneration event according to the AMOX sulfur regeneration request 180 is initiated, the AMOX sulfur regeneration request is received by the sulfur regeneration arbitration module 190, which determines whether the AMOX sulfur regeneration request has priority over other possible regeneration requests, such as the DOC sulfur regeneration request 140, SCR sulfur regeneration request 160, or other requests as will be described in more detail below. If the sulfur regeneration arbitration module 190 determines that the AMOX sulfur regeneration request 180 has priority, then the sulfur regeneration arbitration module generates a sulfur regeneration command 112 that corresponds with the regeneration event parameters demanded by the AMOX sulfur regeneration request.
The sulfur regeneration arbitration module 190 may include a time-based regeneration module or algorithm configured to request a system regeneration event of the exhaust aftertreatment system 22 based on the passing of a preset period of time since the last regeneration event, which may be associated with a predetermined amount of fuel consumed by the engine 20. Accordingly, the sulfur regeneration module 190 monitors the initiation and completion of regeneration events of the exhaust aftertreatment system 22, and monitors the amount of time since the completion of the latest regeneration event. The time since the latent regeneration event can be determined from the time input 192, which can be tied to an internal timer device of the controller 100 or external timer device in communication with the controller. When the preset time has been reached, the time-based regeneration module of the sulfur regeneration arbitration module 190 generates a time-based sulfur regeneration request that demands a regeneration of the exhaust aftertreatment system 22 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The sulfur regeneration arbitration module 190 determines whether the time-based sulfur regeneration request has priority over other possible regeneration requests. If the sulfur regeneration arbitration module 190 determines that the time-based sulfur regeneration request has priority, then the sulfur regeneration arbitration module generates a sulfur regeneration command 112 that corresponds with the regeneration event parameters demanded by the time-based sulfur regeneration request.
The sulfur regeneration arbitration module 190 may include any of various arbitration schemes for determining which of a plurality of regeneration requests has priority. Such arbitration schemes may take into account precalibrated regeneration timers, system efficiency monitors, and accumulation thresholds that are set based on the impact of sulfur on the performance and emissions behavior of one or more of the aftertreatment components of the system 22. For example, the winning request could represent the component that is most severely impacted by sulfur effects if the precalibrated timer has not timed-out and the system efficiency is still normal.
The regeneration event parameters demanded by the DOC, SCR, AMOX, and time-based sulfur regeneration requests can be different. For example, one request may demand a shorter regeneration event that is sufficient to clean sulfur from a corresponding component, but insufficient to clean sulfur from another component. Or, as another example, one request may demand a regeneration event with a lower exhaust gas temperature that is sufficient to clean sulfur from a corresponding component, but insufficient to clean sulfur from another component. To account for such discrepancies, the sulfur modules 130, 150, 170 of the sulfur oxidation module 110 continue to operate as described above during a regeneration event to continuously monitor the storage, release, and accumulation of sulfur on the components while regeneration events are occurring, even if the regeneration event was triggered for a single component. For example, the extra sulfur being released from the DOC 30 during a regeneration event is accounted for in the calculation of the DOC outlet sulfur 142 as extra sulfur being introduced into the SCR catalyst 50. In this manner, an accurate and current estimate of the sulfur accumulation status for each component is known before, during, and after any regeneration event.
As shown in FIG. 4, the hydrocarbon (HC) oxidation module 120 includes a DOC HC module 230, an SCR HC module 250, an AMOX HC module 270, and a HC regeneration arbitration module 290 each similar to the DOC sulfur module 130, an SCR sulfur module 150, an AMOX sulfur module 170, and a sulfur regeneration arbitration module 190, but configured for HC accumulation and removal instead of sulfur accumulation and removal. Each of the DOC HC, SCR HC, and AMOX HC modules 230, 250, 270 generates a respective HC regeneration request 240, 260, 280 if certain estimated conditions are met. The HC regeneration requests 240, 260, 280 are received by the HC regeneration arbitration module 290, which arbitrates between one or more HC regeneration requests, and a timer-based regeneration request, to generate the HC regeneration command 122. The HC regeneration command 122 then represents the characteristics of the winning regeneration request from the arbitration process.
The DOC HC module 230 of the HC oxidation module 120 includes a DOC HC storage module 232, DOC HC release module 234, DOC HC accumulation module 236, and DOC HC regeneration module 238. The DOC HC storage module 232 is configured to estimate the amount of HC being stored on the DOC 30. According to the illustrated embodiment, the DOC HC storage module 232 estimates the amount or quantity of HC being stored on the DOC based on various inputs, such as, for example, the engine out HC 224 (i.e., the quantity of HC in the exhaust gas exiting the engine 20 and entering the DOC 30). In certain implementations, the engine out HC is a function of the fuel rate 124 (i.e., the rate of fuel entering and being consumed by the engine 20). Generally, the engine out HC can be expressed in terms of a volumetric or part-per-minute flow rate. The temperature of the DOC 30 can be determined in a manner similar to that described above.
According to one embodiment, the quantity of HC being stored on the DOC 30, which can be expressed as the rate of HC being stored on the DOC, for a given engine out HC value 224, can be obtained from a look-up table that is stored on the DOC HC storage module 232 and includes predetermined HC storage rates on the DOC 30 compared to DOC temperature values and exhaust mass flow rate values. The DOC HC storage module 232 can include a plurality of look-up tables each associated with a given engine out HC value 224. Accordingly, once the temperature of the DOC 30 and exhaust mass flow rate is determined or known, the HC storage rate on the DOC estimated by the DOC HC storage module 232 is the predetermined value in the look-up table (associated with the determined engine out HC value) for the determined DOC temperature and exhaust flow rate values. Generally, the HC adsorption rate on components is lower at higher exhaust gas temperatures. For engine out HC values between or outside those corresponding with the look-up tables, interpolation or extrapolation techniques can be utilized to estimate the DOC HC storage rate.
The quantity of HC stored on the DOC 30 over a desired time period, which can be represented by the time input 192, is then estimated by the DOC HC storage module 232 by multiplying the estimated DOC HC storage rate by the desired time period. In certain implementations, the quantity of HC stored on the DOC over the desired time period represents an estimate of the newly stored HC, which can be added to a previous estimate of the accumulation of HC on the DOC 30, as will be explained in more detail below, to obtain a more accurate estimate of the quantity of HC currently stored on the DOC.
The DOC HC release module 234 of the DOC HC module 230 is configured to estimate the DOC outlet HC 242 (i.e., the amount or quantity of HC being released from the DOC 30) based on various inputs, such as, for example, the temperature of the DOC and the quantity of HC stored on the DOC. Generally, the HC release rate from components is lower at higher exhaust gas temperatures. The DOC HC release module 234 may estimate the temperature of the DOC 30 in the same or similar manner as the DOC HC storage module 232, or simply utilize the temperature of the DOC estimated by the DOC HC storage module. Similarly, the quantity of HC stored on the DOC 30 can be obtained from the DOC HC storage module 232 or can be based on a previous estimate of the accumulation of HC on the DOC.
According to one embodiment, the DOC outlet HC 242 or amount of HC being released from the DOC 30, which can be expressed as the rate of HC being released from the DOC, can be obtained from a look-up table that is stored on the DOC HC release module 234 and includes predetermined HC release rates from the DOC 30 compared to DOC temperature values and DOC HC storage values. The DOC HC release module 234 can include a plurality of look-up tables each associated with a given DOC outlet HC value. Accordingly, once the temperature of the DOC 30 and DOC outlet HC value is determined or known, the HC release rate from the DOC estimated by the DOC HC release module 234 is the predetermined value in the look-up table for the determined DOC temperature and DOC HC storage values. The quantity of HC released from the DOC 30 over a desired time period (e.g., the same desired time period used by the DOC HC storage module 232 to estimate the DOC HC storage), which also can be represented by the time input 192, is then estimated by the DOC HC release module 234 by multiplying the estimated DOC HC release rate by the desired time period.
The quantity of HC stored on the DOC 30 estimated by the DOC storage module 232 and the DOC outlet HC 242 (or quantity of HC released from the DOC) estimated by the DOC HC release module 234 is used by the DOC HC accumulation module 236 to estimate a total accumulation of HC on the DOC 30. The DOC HC accumulation module 236 estimates the total accumulation of HC on the DOC 30 based on a difference between the estimated quantity of HC stored on the DOC 30 and the estimated quantity of HC released from the DOC. In one implementation, the DOC HC accumulation module 236 sets the total accumulation of HC on the DOC 30 equal to the difference between the estimated quantity of HC stored on the DOC 30 and the estimated quantity of HC released from the DOC.
The DOC HC regeneration module 238 generates a DOC HC regeneration request 240 based on a comparison between the total accumulation of HC on the DOC 30 estimated by the DOC HC accumulation module 236 and a DOC HC accumulation threshold. In one embodiment, the DOC HC regeneration module 238 generates a DOC HC regeneration request 240 only when the total accumulation of HC on the DOC 30 estimated by the DOC HC accumulation module 236 meets (e.g., is equal to or exceeds) the DOC HC accumulation threshold (or other condition thresholds are met). In such an embodiment, should the total accumulation of HC on the DOC 30 estimated by the DOC HC accumulation module 236 not meet the DOC HC accumulation threshold, then a DOC HC regeneration request 240 is not generated. The DOC HC regeneration request 240 represents a demand to regenerate the DOC 30 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The operating parameters of the DOC regeneration event demanded by the DOC HC regeneration request 240 may vary based on any of various factors, such as, for example, the total accumulation of HC on the DOC 30, the period of time since the last DOC regeneration event, and the like. In some implementations, the HC regeneration request 240 is generated even if the total accumulation of HC on the DOC 30 does not meet the DOC HC accumulation threshold. However, in such implementations, the request 140 may be void of regeneration event parameters, such that the request effectively does not demand a regeneration event.
The DOC HC accumulation threshold corresponds with a DOC performance threshold. Like described above, the accumulation of HC on the DOC 30 may have a proportionally negative effect on the performance of the DOC. For example, the greater the accumulation of HC on the DOC 30, the lower the oxidation rate of CO to CO₂and the lower the oxidation of NO to NO₂. Accordingly, the DOC HC accumulation threshold can be predetermined to correspond with a minimum allowable performance characteristic, such as a minimum allowable CO to CO₂oxidation rate and/or minimum allowable NO to NO₂oxidation rate. In this manner, the DOC HC regeneration module 238 is configured to demand a DOC regeneration event by generating the DOC HC regeneration request 240 before the performance of the DOC 30 drops below the minimum allowable performance characteristic.
According to certain embodiments, the DOC HC regeneration module 238 may include an exothermal module 244 that is configured to monitor the exothermal conditions of the DOC 30, which include the heat generation of the DOC. The DOC HC regeneration module 238 compares the exothermal conditions of the DOC 30 against predetermined thresholds and generates a DOC HC regeneration request 240 when the exothermal conditions meet the associated thresholds. In one embodiment, an exothermal condition is a heat generation rate of the DOC 30, and an exothermal condition threshold is a maximum heat generation rate of the DOC. The maximum heat generation rate of the DOC 30 may be associated with a rate above which an uncontrolled or runaway regeneration of the DOC may occur. Alternatively, the exothermal condition is an amount of heat generated by the DOC 30, and the exothermal condition threshold is a maximum allowable amount of heat generated by the DOC. The maximum allowable amount of heat generated by the DOC 30 may be associated with a heat generation value above which an uncontrolled or runaway regeneration of the DOC may occur.
Uncontrolled or runaway regenerations can be mitigated by performing a controlled regeneration of the DOC 30. Accordingly, the DOC HC regeneration module 238 is configured to generate a DOC HC regeneration request 240, which can be considered an exothermal regeneration request under such circumstances, demanding a regeneration event when the exothermal condition meets the exothermal condition threshold, or before an uncontrolled or runaway regeneration event occurs. The parameters of the regeneration event demanded by a DOC HC regeneration request 240 generated from an exothermal condition threshold being met may be different than a DOC HC regeneration request generated from an estimated total HC accumulation on the DOC meeting a DOC HC accumulation threshold.
Before a DOC regeneration event according to the DOC HC regeneration request 240 is initiated, the DOC HC regeneration request is received by the HC regeneration arbitration module 290, which determines whether the DOC HC regeneration request has priority over other possible regeneration requests, as will be described in more detail below. If the HC regeneration arbitration module 290 determines that the DOC HC regeneration request 240 has priority, then the HC regeneration arbitration module generates a HC regeneration command 122 that corresponds with the regeneration event parameters demanded by the DOC HC regeneration request.
The SCR HC module 250 of the HC oxidation module 120 is configured in a manner analogous to the DOC HC module 230 except the SCR HC module applies to the SCR catalyst 50 instead of the DOC 30. For example, the SCR HC module 250 includes an SCR HC storage module 252, SCR HC release module 254, SCR HC accumulation module 256, and SCR HC regeneration module 258. The SCR HC storage module 252 is configured to estimate the amount of HC being stored on the SCR catalyst 50. According to the illustrated embodiment, the SCR HC storage module 252 estimates the amount or quantity of HC being stored on the SCR based on various inputs, such as, for example, the DOC outlet HC 242 estimated by the DOC HC release module 234 (i.e., the quantity of HC in the exhaust gas exiting the DOC 30 and entering the SCR catalyst 50), the temperature of the SCR catalyst 50, and the mass flow rate of exhaust gas into the SCR catalyst. The temperature of the SCR catalyst 50 can be determined by the SCR HC storage module 252 according to any of various techniques as discussed above.
According to one embodiment, the quantity of HC being stored on the SCR catalyst 50, which can be expressed as the rate of HC being stored on the SCR catalyst 50, for a given DOC outlet HC value 242, can be obtained from a look-up table that is stored on the SCR HC storage module 252 and includes predetermined HC storage rates on the SCR catalyst 50 compared to SCR catalyst temperature values and exhaust mass flow rate values. The SCR HC storage module 252 can include a plurality of look-up tables each associated with a given DOC outlet HC value 242. Accordingly, once the temperature of the SCR catalyst 50 and exhaust mass flow rate is determined or known, the HC storage rate on the SCR catalyst estimated by the SCR HC storage module 252 is the predetermined value in the look-up table (associated with the determined DOC outlet HC value 242) for the determined SCR catalyst temperature and exhaust flow rate values. For DOC outlet HC values 242 between or outside those corresponding with the look-up tables, interpolation or extrapolation techniques can be utilized to estimate the SCR HC storage rate.
The quantity of HC stored on the SCR catalyst 50 over a desired time period, which can be represented by the time input 192, is then estimated by the SCR HC storage module 252 by multiplying the estimated SCR HC storage rate by the desired time period. In certain implementations, the quantity of HC stored on the SCR catalyst 50 over the desired time period represents an estimate of the newly stored HC on the SCR catalyst, which can be added to a previous estimate of the accumulation of HC on the SCR catalyst, as will be explained in more detail below, to obtain a more accurate estimate of the quantity of HC currently stored on the SCR catalyst.
The SCR HC release module 254 of the SCR HC module 250 is configured to estimate the SCR outlet HC 262 (i.e., the amount or quantity of HC being released from the SCR catalyst 50) based on various inputs, such as, for example, the temperature of the SCR catalyst and the quantity of HC stored on the SCR catalyst. The SCR HC release module 254 may estimate the temperature of the SCR catalyst 50 in the same or similar manner as the SCR HC storage module 252, or simply utilize the temperature of the SCR catalyst estimated by the SCR HC storage module. Similarly, the quantity of HC stored on the SCR catalyst 50 can be obtained from the SCR HC storage module 252 or can be based on a previous estimate of the accumulation of HC on the SCR catalyst.
According to one embodiment, the SCR outlet HC 262 or amount of HC being released from the SCR catalyst 50, which can be expressed as the rate of HC being released from the SCR catalyst, can be obtained from a look-up table that is stored on the SCR HC release module 254 and includes predetermined HC release rates from the SCR catalyst 50 compared to SCR catalyst temperature values and SCR catalyst HC storage values. The SCR HC release module 254 can include a plurality of look-up tables each associated with a given SCR outlet HC value 262. Accordingly, once the temperature of the SCR catalyst 50 and SCR outlet HC value 262 is determined or known, the HC release rate from the SCR catalyst 50 estimated by the SCR HC release module 254 is the predetermined value in the look-up table for the determined SCR temperature and SCR HC storage values. The quantity of HC released from the SCR catalyst 50 over a desired time period (e.g., the same desired time period used by the SCR HC storage module 252 to estimate the SCR HC storage), which also can be represented by the time input 192, is then estimated by the SCR HC release module 254 by multiplying the estimated SCR HC release rate by the desired time period.
The quantity of HC stored on the SCR catalyst 50 estimated by the SCR HC storage module 252 and the SCR outlet HC 262 (or quantity of HC released from the SCR catalyst) estimated by the SCR HC release module 254 is used by the SCR HC accumulation module 256 to estimate a total accumulation of HC on the SCR catalyst 50. The SCR HC accumulation module 256 estimates the total accumulation of HC on the SCR catalyst 50 based on a difference between the estimated quantity of HC stored on the SCR catalyst 50 and the estimated quantity of HC released from the SCR catalyst. In one implementation, the SCR HC accumulation module 256 sets the total accumulation of HC on the SCR catalyst 50 equal to the difference between the estimated quantity of HC stored on the SCR catalyst and the estimated quantity of HC released from the SCR catalyst.
The SCR HC regeneration module 258 generates an SCR HC regeneration request 260 based on a comparison between the total accumulation of HC on the SCR catalyst 50 estimated by the SCR HC accumulation module 256 and an SCR HC accumulation threshold. In one embodiment, the SCR HC regeneration module 258 generates an SCR HC regeneration request 260 only when the total accumulation of HC on the SCR catalyst 50 estimated by the SCR HC accumulation module 256 meets (e.g., is equal to or exceeds) the SCR HC accumulation threshold. In such an embodiment, should the total accumulation of HC on the SCR catalyst 50 estimated by the SCR HC accumulation module 256 not meet the SCR HC accumulation threshold, then an SCR HC regeneration request 260 is not generated. The SCR HC regeneration request 260 represents a demand to regenerate the SCR catalyst 50 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The operating parameters of the SCR catalyst regeneration event demanded by the SCR HC regeneration request 260 may vary based on any of various factors, such as, for example, the total accumulation of HC on the SCR catalyst 50, the period of time since the last SCR catalyst regeneration event, and the like. In some implementations, the HC regeneration request 260 is generated even if the total accumulation of HC on the SCR catalyst 50 does not meet the SCR HC accumulation threshold. However, in such implementations, the request 260 may be void of regeneration event parameters, such that the request effectively does not demand a regeneration event.
The SCR HC accumulation threshold corresponds with an SCR catalyst performance threshold. Like described above, the accumulation of HC on the SCR catalyst 50 may have a proportionally negative effect on the performance of the SCR catalyst. For example, the greater the accumulation of HC on the SCR catalyst 50, the lower the conversion rate of NOx in the presence of ammonia or the lower the NOx conversion efficiency. Accordingly, the SCR HC accumulation threshold can be predetermined to correspond with a minimum allowable performance characteristic, such as a minimum allowable NOx conversion rate or efficiency. In this manner, the SCR HC regeneration module 258 is configured to demand an SCR catalyst regeneration event by generating the SCR HC regeneration request 260 before the performance of the SCR catalyst 50 drops below the minimum allowable performance characteristic. Because the performance characteristics of the DOC 30 are different than those of the SCR catalyst 50, the respective HC accumulation thresholds can be different. For example, in certain implementations, the performance of the DOC 30 may better tolerate HC accumulations than the SCR catalyst 50. Accordingly, in such implementations, the HC accumulation threshold of the DOC 30 may be higher than that of the SCR catalyst 50. In AMOX other implementations, the HC accumulation threshold of the DOC 30 may be lower than that of the SCR catalyst 50.
Before an SCR catalyst regeneration event according to the SCR HC regeneration request 260 is initiated, the SCR HC regeneration request is received by the HC regeneration arbitration module 290, which determines whether the SCR HC regeneration request has priority over other possible regeneration requests, such as the DOC HC regeneration request 240 or other requests as will be described in more detail below. If the HC regeneration arbitration module 290 determines that the SCR HC regeneration request 260 has priority, then the HC regeneration arbitration module generates a HC regeneration command 122 that corresponds with the regeneration event parameters demanded by the SCR HC regeneration request.
The AMOX HC module 270 of the HC oxidation module 120 is configured in a manner analogous to the DOC and SCR HC modules 230, 250 except the AMOX HC module applies to the AMOX catalyst 60 instead of the DOC 30 and SCR catalyst 50. For example, the AMOX HC module 270 includes an AMOX HC storage module 272, AMOX HC release module 274, AMOX HC accumulation module 276, and AMOX HC regeneration module 278. The AMOX HC storage module 272 is configured to estimate the amount of HC being stored on the AMOX catalyst 60. According to the illustrated embodiment, the AMOX HC storage module 272 estimates the amount or quantity of HC being stored on the AMOX based on various inputs, such as, for example, the SCR outlet HC 262 estimated by the SCR HC release module 254 (i.e., the quantity of HC in the exhaust gas exiting the SCR catalyst 50 and entering the AMOX catalyst 60), the temperature of the AMOX catalyst 60, and the mass flow rate of exhaust gas into the AMOX catalyst. The temperature of the AMOX catalyst 60 (e.g., the catalyst bed of the AMOX catalyst) can be determined by the AMOX HC storage module 272 according to any of various techniques, such as using estimation modules and/or physical sensors. For example, the temperature of the AMOX catalyst 60 can be determined based on the difference between exhaust gas temperature measurements taken by the temperature sensors 12 upstream and downstream of the AMOX catalyst 60. Additionally, or alternatively, the exhaust aftertreatment system 22 may have an AMOX catalyst mid-bed temperature sensor that more directly detects the temperature of the AMOX catalyst 60.
According to one embodiment, the quantity of HC being stored on the AMOX catalyst 60, which can be expressed as the rate of HC being stored on the AMOX catalyst, for a given SCR outlet HC value 262, can be obtained from a look-up table that is stored on the AMOX HC storage module 272 and includes predetermined HC storage rates on the AMOX catalyst 60 compared to AMOX catalyst temperature values and exhaust mass flow rate values. The AMOX HC storage module 272 can include a plurality of look-up tables each associated with a given SCR outlet HC value 262. Accordingly, once the temperature of the AMOX catalyst 60 and exhaust mass flow rate is determined or known, the HC storage rate on the AMOX catalyst estimated by the AMOX HC storage module 272 is the predetermined value in the look-up table (associated with the determined SCR outlet HC value 262) for the determined AMOX catalyst temperature and exhaust flow rate values. For SCR outlet HC values 262 between or outside those corresponding with the look-up tables, interpolation or extrapolation techniques can be utilized to estimate the AMOX HC storage rate.
The quantity of HC stored on the AMOX catalyst 60 over a desired time period, which can be represented by the time input 192, is then estimated by the AMOX HC storage module 272 by multiplying the estimated AMOX HC storage rate by the desired time period. In certain implementations, the quantity of HC stored on the AMOX catalyst 60 over the desired time period represents an estimate of the newly stored HC on the AMOX catalyst, which can be added to a previous estimate of the accumulation of HC on the AMOX catalyst, as will be explained in more detail below, to obtain a more accurate estimate of the quantity of HC currently stored on the AMOX catalyst.
The AMOX HC release module 274 of the AMOX HC module 270 is configured to estimate the AMOX outlet HC 282 (i.e., the amount or quantity of HC being released from the AMOX catalyst 60) based on various inputs, such as, for example, the temperature of the AMOX catalyst and the quantity of HC stored on the AMOX catalyst. The AMOX HC release module 274 may estimate the temperature of the AMOX catalyst 60 in the same or similar manner as the AMOX HC storage module 272, or simply utilize the temperature of the AMOX catalyst estimated by the AMOX HC storage module. Similarly, the quantity of HC stored on the AMOX catalyst 60 can be obtained from the AMOX HC storage module 272 or can be based on a previous estimate of the accumulation of HC on the AMOX catalyst 60.
According to one embodiment, the AMOX outlet HC 282 or amount of HC being released from the AMOX catalyst 60, which can be expressed as the rate of HC being released from the AMOX catalyst, can be obtained from a look-up table that is stored on the AMOX HC release module 274 and includes predetermined HC release rates from the AMOX catalyst 60 compared to AMOX catalyst temperature values and AMOX catalyst HC storage values. The AMOX HC release module 274 can include a plurality of look-up tables each associated with a given AMOX outlet HC value 282. Accordingly, once the temperature of the AMOX catalyst 60 and AMOX outlet HC value 282 is determined or known, the HC release rate from the AMOX catalyst 60 estimated by the AMOX HC release module 274 is the predetermined value in the look-up table for the determined AMOX temperature and AMOX HC storage values. The quantity of HC released from the AMOX catalyst 60 over a desired time period (e.g., the same desired time period used by the AMOX HC storage module 272 to estimate the AMOX HC storage), which also can be represented by the time input 192, is then estimated by the AMOX HC release module 274 by multiplying the estimated AMOX HC release rate by the desired time period.
The quantity of HC stored on the AMOX catalyst 60 estimated by the AMOX HC storage module 272 and the AMOX outlet HC 282 (or quantity of HC released from the AMOX catalyst) estimated by the AMOX HC release module 274 is used by the AMOX HC accumulation module 276 to estimate a total accumulation of HC on the AMOX catalyst 60. The AMOX HC accumulation module 276 estimates the total accumulation of HC on the AMOX catalyst 60 based on a difference between the estimated quantity of HC stored on the AMOX catalyst 60 and the estimated quantity of HC released from the AMOX catalyst. In one implementation, the AMOX HC accumulation module 276 sets the total accumulation of HC on the AMOX catalyst 60 equal to the difference between the estimated quantity of HC stored on the AMOX catalyst and the estimated quantity of HC released from the AMOX catalyst.
The AMOX HC regeneration module 278 generates an AMOX HC regeneration request 280 based on a comparison between the total accumulation of HC on the AMOX catalyst 60 estimated by the AMOX HC accumulation module 276 and an AMOX HC accumulation threshold. In one embodiment, the AMOX HC regeneration module 278 generates an AMOX HC regeneration request 280 only when the total accumulation of HC on the AMOX catalyst 60 estimated by the AMOX HC accumulation module 276 meets (e.g., is equal to or exceeds) the AMOX HC accumulation threshold. In such an embodiment, should the total accumulation of HC on the AMOX catalyst 60 estimated by the AMOX HC accumulation module 276 not meet the AMOX HC accumulation threshold, then an AMOX HC regeneration request 280 is not generated. The AMOX HC regeneration request 280 represents a demand to regenerate the AMOX catalyst 60 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The operating parameters of the AMOX catalyst regeneration event demanded by the AMOX HC regeneration request 280 may vary based on any of various factors, such as, for example, the total accumulation of HC on the AMOX catalyst 60, the period of time since the last AMOX catalyst regeneration event, and the like. In some implementations, the HC regeneration request 280 is generated even if the total accumulation of HC on the AMOX catalyst 60 does not meet the AMOX HC accumulation threshold. However, in such implementations, the request 280 may be void of regeneration event parameters, such that the request effectively does not demand a regeneration event.
The AMOX HC accumulation threshold corresponds with an AMOX catalyst performance threshold. Like described above, the accumulation of HC on the AMOX catalyst 60 may have a proportionally negative effect on the performance of the AMOX catalyst. For example, the greater the accumulation of HC on the AMOX catalyst 60, the lower the conversion rate of ammonia or the lower the ammonia conversion efficiency. Accordingly, the AMOX HC accumulation threshold can be predetermined to correspond with a minimum allowable performance characteristic, such as a minimum allowable ammonia conversion rate or efficiency. In this manner, the AMOX HC regeneration module 278 is configured to demand an AMOX catalyst regeneration event by generating the SCR HC regeneration request 260 before the performance of the AMOX catalyst 60 drops below the minimum allowable performance characteristic. Because the performance characteristics of the DOC 30 and SCR catalyst 50 are different than those of the AMOX catalyst 60, the respective HC accumulation thresholds can be different. For example, in certain implementations, the performance of the DOC 30 and/or SCR catalyst 50 may better tolerate HC accumulations than the AMOX catalyst 60. Accordingly, in such implementations, the HC accumulation thresholds of the DOC 30 and/or SCR catalyst 50 may be higher than that of the AMOX catalyst 60. In other implementations, the HC accumulation threshold of the DOC 30 and/or SCR catalyst 50 may be lower than that of the AMOX catalyst 60.
According to certain embodiments, the AMOX HC regeneration module 278 may include an exothermal module 280 that is configured to monitor the exothermal conditions of the AMOX catalyst 60, which include the heat generation of the AMOX catalyst. The AMOX HC regeneration module 278 compares the exothermal conditions of the AMOX catalyst 60 against predetermined thresholds and generates an AMOX HC regeneration request 280 when the exothermal conditions meet the associated thresholds. In one embodiment, an exothermal condition is a heat generation rate of the AMOX catalyst 60, and an exothermal condition threshold is a maximum heat generation rate of the AMOX catalyst. The maximum heat generation rate of the AMOX catalyst 60 may be associated with a rate above which an uncontrolled or runaway regeneration of the AMOX catalyst may occur. Alternatively, the exothermal condition is an amount of heat generated by the AMOX catalyst 60, and the exothermal condition threshold is a maximum allowable amount of heat generated by the AMOX catalyst. The maximum allowable amount of heat generated by the DOC 30 may be associated with a heat generation value above which an uncontrolled or runaway regeneration of the DOC may occur. Uncontrolled or runaway regenerations can be mitigated by performing a controlled regeneration of the AMOX catalyst 60. Accordingly, the AMOX HC regeneration module 278 is configured to generate an AMOX HC regeneration request 280 demanding a regeneration event when the exothermal condition meets the exothermal condition threshold, or before an uncontrolled or runaway regeneration event occurs. The parameters of the regeneration event demanded by an AMOX HC regeneration request 280 generated from an exothermal condition threshold being met may be different than an AMOX HC regeneration request generated from an estimated total HC accumulation on the AMOX catalyst meeting an AMOX HC accumulation threshold.
Before an AMOX catalyst regeneration event according to the AMOX HC regeneration request 280 is initiated, the AMOX HC regeneration request is received by the HC regeneration arbitration module 290, which determines whether the AMOX HC regeneration request has priority over other possible regeneration requests, such as the DOC HC regeneration request 240, SCR HC regeneration request 260, or other requests as will be described in more detail below. If the HC regeneration arbitration module 290 determines that the AMOX HC regeneration request 280 has priority, then the HC regeneration arbitration module generates a HC regeneration command 122 that corresponds with the regeneration event parameters demanded by the AMOX HC regeneration request.
The HC regeneration arbitration module 290 may include a time-based regeneration module or algorithm configured to request a regeneration event of the exhaust aftertreatment system 22 based on the passing of a preset period of time since the last regeneration event, which may be associated with a predetermined amount of fuel consumed by the engine 20. Accordingly, the HC regeneration module 290 monitors the initiation and completion of regeneration events of the exhaust aftertreatment system 22, and monitors the amount of time since the completion of the latest regeneration event. The time since the latent regeneration event can be determined from the time input 292, which can be tied to an internal timer device of the controller 100 or external timer device in communication with the controller. When the preset time has been reached, the time-based regeneration module of the HC regeneration arbitration module 290 generates a time-based HC regeneration request that demands a regeneration of the exhaust aftertreatment system 22 at specific regeneration event operating parameters (e.g., exhaust temperature, exhaust mass flow rate, and timing parameter). The HC regeneration arbitration module 290 determines whether the time-based HC regeneration request has priority over other possible regeneration requests. If the HC regeneration arbitration module 290 determines that the time-based HC regeneration request has priority, then the HC regeneration arbitration module generates a HC regeneration command 122 that corresponds with the regeneration event parameters demanded by the time-based HC regeneration request.
The HC regeneration arbitration module 290 may include any of various arbitration schemes for determining which of a plurality of regeneration requests has priority. Such arbitration schemes may take into account precalibrated regeneration timers, system efficiency monitors, and accumulation thresholds that are set based on the impact of HC on the performance and emissions behavior of one or more of the aftertreatment components of the system 22. For example, the winning request could represent the component that is most severely impacted by HC effects if the precalibrated timer has not timed-out and the system efficiency is still normal.
The regeneration event parameters demanded by the DOC, SCR, AMOX, and time-based HC regeneration requests can be different. For example, one request may demand a shorter regeneration event that is sufficient to clean HC from a corresponding component, but insufficient to clean HC from another component. Or, as another example, one request may demand a regeneration event with a lower exhaust gas temperature that is sufficient to clean HC from a corresponding component, but insufficient to clean HC from another component. To account for such discrepancies, the HC modules 230, 250, 270 of the HC oxidation module 120 continue to operate as described above during a regeneration event to continuously monitor the storage, release, and accumulation of HC on the components while regeneration events are occurring, even if the regeneration event was triggered for a single component. For example, the extra HC being released from the DOC 30 during a regeneration event is accounted for in the calculation of the DOC outlet HC 242 as extra HC being introduced into the SCR catalyst 50. In this manner, an accurate and current estimate of the HC accumulation status for each component is known before, during, and after any regeneration event.
In certain embodiments of a controller 100 having both a sulfur oxidation module 110 and hydrocarbon oxidation module 120, the sulfur and HC regeneration arbitration modules 190, 290 may be combined to form a single arbitration module. The single arbitration module would be configured to arbitrate between sulfur regeneration requests and HC regeneration requests to determine which of multiple requests has priority.
Although not shown, the controller 100 can include other poison oxidation modules configured analogously to the sulfur and HC oxidation modules 110, 120 to estimate poison accumulation levels on the components of the exhaust aftertreatment system 22 and request regeneration events if the poison accumulation levels reach corresponding predetermined thresholds. For example, the controller 100 can include a water oxidation module that estimate water accumulation levels on the components of the exhaust aftertreatment system 22 and requests regenerations event if the water accumulation levels reach corresponding predetermined water accumulation thresholds. Other poisons can include platinum (or other precious metals migrated from the DOC 30 to the SCR catalyst 50, alkali salts (e.g., Na and K from contaminated urea solutions), and phosphorus and zinc from lubrication oil. Additionally, the thermal degradation of a catalyst, which is characterized by the progressive loss of reaction sites, can be considered a type of poison applicable to the present disclosure.
Additionally, although not shown, for embodiments with exhaust aftertreatment systems 22 that include a DPF 40, each of the sulfur and hydrocarbon oxidation modules 110, 120 of the controller 100 can include a DPF sulfur and HC module, respectively. In such embodiments, the DPF sulfur and HC modules are configured in a manner analogous to the DOC, SCR, and AMOX sulfur modules 130, 150, 170, and the SCR HC module 250, respectively, except the DPF sulfur and HC modules apply to the condition and regeneration of the DPF 40.
Referring to FIG. 5, a method 300 for separately estimating conditions of aftertreatment system components and regenerating the components is shown. In certain implementations, the steps of the method 300 may be executed by the modules of the controller 100 described above.
The method 300 begins by estimating the quantity of a poison accumulated on a DOC at 310. If the poison accumulation on the DOC is above or at least meets an associated threshold at 320, then the method 300 commands a regeneration of the DOC at 380, which at least partially regenerates other components of the aftertreatment system. However, if the poison accumulation on the DOC is below or does not meet the associated threshold at 320, then the method 300 proceeds to estimate the quantity of a poison accumulated on an SCR catalyst at 330. If the poison accumulation on the SCR catalyst is above or at least meets an associated threshold at 340, then the method 300 commands a regeneration of the SCR catalyst at 380, which at least partially regenerates other components of the aftertreatment system. However, if the poison accumulation on the SCR catalyst is below or does not meet the associated threshold at 340, then the method 300 proceeds to estimate the quantity of a poison accumulated on an AMOX catalyst at 350. If the poison accumulation on the AMOX catalyst is above or at least meets an associated threshold at 360, then the method 300 commands a regeneration of the AMOX catalyst at 380, which at least partially regenerates other components of the aftertreatment system. However, if the poison accumulation on the AMOX catalyst is below or does not meet the associated threshold at 360, then the method 300 proceeds to determine if a predetermined period of time has passed since a previous regeneration event at 370. If the predetermined period of time has passed at 370, then the method 300 commands a regeneration of the components of the aftertreatment system. However, if the predetermined period of time has not passed at 370, then the method 300 does not command a regeneration event and ends.
In certain implementations, the poison of the method 300 can be one or both of sulfur and HC. In some implementations, the poison of the method 300 can be water. According to some embodiments, the estimation of the accumulation of the poison on the SCR catalyst at 330 is at least indirectly dependent on the estimate of the accumulation of the poison on the DOC Likewise, the estimation of the accumulation of the poison on the AMOX catalyst at 370 can be at least indirectly dependent on the estimate of the accumulation of the poison on the SCR catalyst. Also, in some embodiments, the estimation of the poison accumulation on the DOC, SCR catalyst, and AMOX catalyst includes estimations of the amount of poison being stored and the amount of poison being released from the DOC, SCR catalyst, and AMOX catalyst, respectively. Although not shown, in some implementations, the method 300 may include estimating an exothermic condition for each of the DOC and AMOX catalysts, and command a regeneration event at 380 if the exothermic condition for the DOC and AMOX catalysts meet an associated threshold.
The schematic flow chart diagrams and method schematic diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of representative embodiments. Other steps, orderings and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the methods illustrated in the schematic diagrams.
Additionally, the format and symbols employed are provided to explain the logical steps of the schematic diagrams and are understood not to limit the scope of the methods illustrated by the diagrams. Although various arrow types and line types may be employed in the schematic diagrams, they are understood not to limit the scope of the corresponding methods. Indeed, some arrows or other connectors may be used to indicate only the logical flow of a method. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of a depicted method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and program code.
Many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.
Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.
Indeed, a module of computer readable program code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. Where a module or portions of a module are implemented in software, the computer readable program code may be stored and/or propagated on in one or more computer readable medium(s).
The computer readable medium may be a tangible computer readable storage medium storing the computer readable program code. The computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.
More specific examples of the computer readable medium may include but are not limited to a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), an optical storage device, a magnetic storage device, a holographic storage medium, a micromechanical storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, and/or store computer readable program code for use by and/or in connection with an instruction execution system, apparatus, or device.
The computer readable medium may also be a computer readable signal medium. A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electrical, electro-magnetic, magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport computer readable program code for use by or in connection with an instruction execution system, apparatus, or device. Computer readable program code embodied on a computer readable signal medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, Radio Frequency (RF), or the like, or any suitable combination of the foregoing
In one embodiment, the computer readable medium may comprise a combination of one or more computer readable storage mediums and one or more computer readable signal mediums. For example, computer readable program code may be both propagated as an electro-magnetic signal through a fiber optic cable for execution by a processor and stored on RAM storage device for execution by the processor.
Computer readable program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
The program code may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks.
The program code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the program code which executed on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, however, absent an express correlation to indicate otherwise, an implementation may be associated with one or more embodiments.
The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

What is claimed is:

1. An apparatus for an exhaust aftertreatment system, comprising:

a first aftertreatment component poison module configured to generate a first component poison regeneration request based on an estimated accumulation of a first poison on the first aftertreatment component, the accumulation of the first poison on the first aftertreatment component being based on an estimated amount of the first poison being released from the first aftertreatment component; and

a second aftertreatment component poison module configured to generate a second component poison regeneration request based on an estimated accumulation of the first poison on the second aftertreatment component, the accumulation of the first poison on the second aftertreatment component being based on the estimated amount of the first poison being released from the first aftertreatment component.

2. The apparatus of claim 1, further comprising a poison regeneration arbitration module configured to generate a poison regeneration command based on an arbitration of the first and second component poison regeneration requests.

3. The apparatus of claim 2, further comprising a time-based regeneration module configured to generate a system regeneration request based on a passage of a preset period of time, wherein the poison regeneration arbitration module is configured to generate the poison regeneration command based on an arbitration of the first component poison regeneration request, second component poison regeneration request, and system regeneration request.

4. The apparatus of claim 1, wherein the accumulation of the first poison on the second aftertreatment component is based on an estimated amount of the first poison being released from the second aftertreatment component, the apparatus further comprising a third aftertreatment component poison module configured to generate a third component poison regeneration request based on an estimated accumulation of the first poison on the third aftertreatment component, the accumulation of the first poison on the third aftertreatment component being based on the estimated amount of the first poison being released from the second aftertreatment component.

5. The apparatus of claim 1, wherein:

the first aftertreatment component poison module is configured to estimate an amount of the first poison being stored on the first aftertreatment component, wherein the accumulation of the first poison on the first aftertreatment component is based on a difference between the amount of the first poison being stored on the first aftertreatment component and the amount of the first poison being released from the first aftertreatment component; and

the second aftertreatment component poison module is configured to estimate an amount of the first poison being stored on the second aftertreatment component, wherein the accumulation of the first poison on the second aftertreatment component is based on a difference between the amount of the first poison being stored on the second aftertreatment component and the amount of the first poison being released from the second aftertreatment component.

6. The apparatus of claim 5, wherein:

the amount of the first poison being stored on the first aftertreatment component is estimated based on a temperature of the first aftertreatment component and a mass flow rate of exhaust gas into the first aftertreatment component; and

the amount of the first poison being stored on the second aftertreatment component is estimated based on a temperature of the second aftertreatment component and a mass flow rate of exhaust gas into the second aftertreatment component.

7. The apparatus of claim 6, wherein:

the amount of the first poison being released from the first aftertreatment component is estimated based on the temperature of the first aftertreatment component and the amount of the first poison being stored on the first aftertreatment component; and

the amount of the first poison being released from the second aftertreatment component is estimated based on the temperature of the second aftertreatment component and the amount of the first poison being stored on the second aftertreatment component.

8. The apparatus of claim 1, wherein the first component poison regeneration request comprises first regeneration event parameters and the second component poison regeneration request comprises second regeneration event parameters, wherein the first regeneration event parameters are different than the second regeneration event parameters.

9. The apparatus of claim 1, wherein the first poison comprises one of sulfur, hydrocarbon, or water.

10. The apparatus of claim 1, wherein:

the first aftertreatment component comprises one of a diesel oxidation catalyst, a diesel particulate filter, a selective catalytic reduction catalyst, or an ammonia oxidation catalyst; and

the second aftertreatment component comprises another one of the diesel oxidation catalyst, diesel particulate filter, selective catalytic reduction catalyst, or ammonia oxidation catalyst.

11. The apparatus of claim 1, further comprising:

a third aftertreatment component poison module configured to generate a third component poison regeneration request based on an estimated accumulation of a second poison on the first aftertreatment component, the accumulation of the second poison on the first aftertreatment component being based on an amount of the second poison being released from the first aftertreatment component; and

a fourth aftertreatment component poison module configured to generate a fourth component poison regeneration request based on an estimated accumulation of the second poison on the second aftertreatment component, the accumulation of the second poison on the second aftertreatment component being based on the estimated amount of the second poison being released from the first aftertreatment component.

12. The apparatus of claim 2, wherein the poison regeneration arbitration module is further configured to generate the poison regeneration command based on an arbitration of the first, second, third, and fourth component poison regeneration requests.

13. The apparatus of claim 1, wherein:

the first aftertreatment component poison module generates the first component poison regeneration request when the estimated accumulation of the first poison on the first aftertreatment component meets a first poison accumulation threshold, the first poison accumulation threshold corresponding with a minimum allowable performance characteristic of the first aftertreatment component; and

the second aftertreatment component poison module generates the second component poison regeneration request when the estimated accumulation of the first poison on the second aftertreatment component meets a second poison accumulation threshold, the second poison accumulation threshold corresponding with a minimum allowable performance characteristic of the second aftertreatment component.

14. The apparatus of claim 13, wherein the first poison accumulation threshold is different than the second poison accumulation threshold.

15. The apparatus of claim 13, wherein:

the first aftertreatment component comprises one of a diesel oxidation catalyst, a selective catalytic reduction catalyst, or an ammonia oxidation catalyst, and the minimum allowable performance characteristic of the first aftertreatment component comprises one of a minimum allowable NO to NO₂oxidation efficiency, a minimum allowable NOx conversion efficiency, or a minimum allowable ammonia oxidation efficiency, respectively; and

the second aftertreatment component comprises another one of the diesel oxidation catalyst, selective catalytic reduction catalyst, or ammonia oxidation catalyst, and the minimum allowable performance characteristic of the second aftertreatment component comprises one of the minimum allowable NO to NO₂oxidation efficiency, minimum allowable NOx conversion efficiency, or minimum allowable ammonia oxidation efficiency, respectively

16. The apparatus of claim 1, wherein the first poison comprises hydrocarbon, and wherein at least the first aftertreatment component poison module comprises an exothermal module configured to monitor an exothermal condition of the first aftertreatment component, and wherein the first aftertreatment component poison module generates an exothermal regeneration request when the exothermal condition meets an exothermal condition threshold.

17. An exhaust aftertreatment system in exhaust gas receiving communication with an internal combustion engine, comprising:

a diesel oxidation catalyst (DOC);

a selective catalytic reduction (SCR) catalyst downstream of the DOC;

an ammonia oxidation (AMOX) catalyst downstream of the SCR catalyst;

a DOC poison module configured to estimate an accumulation of a first poison on the DOC, and configured to request regeneration of the DOC when the accumulation of the first poison on the DOC meets a first predetermined poison accumulation threshold corresponding with a minimum desirable NO to NO₂oxidation efficiency of the DOC;

an SCR poison module configured to estimate an accumulation of the first poison on the SCR catalyst, and configured to request regeneration of the SCR catalyst when the accumulation of the first poison on the SCR catalyst meets a second predetermined poison accumulation threshold corresponding with a minimum desirable NOx conversion efficiency of the SCR catalyst; and

an AMOX poison module configured to estimate an accumulation of the first poison on the AMOX catalyst, and configured to request regeneration of the AMOX catalyst when the accumulation of the first poison on the AMOX catalyst meets a third predetermined poison accumulation threshold corresponding with a minimum desirable ammonia oxidation efficiency of the AMOX catalyst.

18. The exhaust aftertreatment system of claim 17, wherein:

the DOC poison module is further configured to estimate an amount of poison being released from the internal combustion engine and an amount of poison being released from the DOC, the estimate of the accumulation of the first poison on the DOC being based on the amount of poison being released from the internal combustion engine;

the SCR poison module is further configured to estimate an amount of poison being released from the SCR catalyst, the estimate of the accumulation of the first poison on the SCR catalyst being based on the amount of poison being released from the DOC; and

the estimate of the accumulation of the first poison on the AMOX catalyst is based on the amount of poison being released from the SCR catalyst.

19. A method for estimating conditions of and regenerating exhaust aftertreatment system components, comprising:

estimating an accumulated quantity of a poison on a first aftertreatment component;

commanding a regeneration of the exhaust aftertreatment system if the accumulated quantity of the poison on the first aftertreatment component meets a first threshold associated with a performance characteristic of the first aftertreatment component;

estimating an accumulated quantity of the poison on a second aftertreatment component; and

commanding a regeneration of the exhaust aftertreatment system if the accumulated quantity of the poison on the second aftertreatment component meets a second threshold associated with a performance characteristic of the second aftertreatment component.

20. The method of claim 19, further comprising:

determining an amount of the poison entering the first aftertreatment component, wherein estimating the accumulated quantity of the poison on the first aftertreatment component is based on the amount of the poison entering the first aftertreatment component; and

estimating an amount of poison being released from the first aftertreatment component, wherein estimating the accumulated quantity of the poison on the second aftertreatment component is based on the amount of poison being released from the first aftertreatment component.