Systems and methods for controlling regeneration of aftertreatment systems including multiple legs

A controller for controlling regeneration in an aftertreatment system comprising a first leg and a second leg is configured to: determine whether regeneration is permitted by the engine based on engine operating parameters; in response to regeneration being permitted, determine whether regeneration is required in at least one of the first leg or the second leg based on operating parameters of the first leg and the second leg, and whether regeneration is inhibited in either the first leg or the second leg; and in response to determining that (i) regeneration is required in at least one of the first or second leg, and (ii) regeneration is not inhibited in either the first or the second leg, cause insertion of hydrocarbons into the engine to thereby increase the temperature of the exhaust gas to a target temperature and cause regeneration in each of the first and second leg.

TECHNICAL FIELD

The present disclosure relates generally to aftertreatment systems for use with internal combustion (IC) engines.

BACKGROUND

Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by engines such as IC engines. Conventional exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) catalyst formulated to convert NOx (NO and NO2in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3).

Generally, a reductant such as a diesel exhaust fluid (e.g., an aqueous urea solution) is inserted into the aftertreatment system as a source of ammonia. The reductant facilitates the decomposition of the constituents of the exhaust gas by the SCR catalyst. During use, the reductant may be deposited on the SCR catalyst. Over time, the reductant deposits can build up and lead to reduction in a SCR catalytic conversion efficiency (CE) of the SCR catalyst. Heat may be requested from the engine to heat the exhaust gas to remove the reductant deposits and regenerate the SCR catalyst. Moreover, filters included in aftertreatment systems can also be plugged with particulate matter, and may also be regenerated during the regeneration process.

Some aftertreatment systems include two or more legs, each of which includes various components of the aftertreatment system. Exhaust gas generated by the engine is divided into portions that flow into each leg of the aftertreatment system. Conventional aftertreatment systems insert hydrocarbons in each of the legs of the aftertreatment system to cause regeneration. While this allows independent control of regeneration in each leg, such aftertreatment systems may increase hardware requirements.

SUMMARY

Embodiments described herein relate generally to systems and methods for regeneration in aftertreatment systems that include a first leg and a second leg, and in particular, to aftertreatment systems that include a controller configured to determine whether regeneration is required by a SCR catalyst and/or a filter disposed in in either of the first leg or the second leg of the aftertreatment system, and initiate regeneration in each of the first leg and the second leg to cause regeneration in each leg when one of the legs requires regeneration, and stop regeneration once each leg has completed regeneration.

In some embodiments, a controller for controlling regeneration of at least one of a SCR catalyst or a filter included in a first leg or a second leg of an aftertreatment system, the first leg structured to receive a first portion of an exhaust gas produced by an engine, and the second leg structured to receive a second portion of the exhaust gas, is configured to: determine whether regeneration is permitted by the engine based on engine operating parameters; in response to determining that regeneration is permitted by the engine, determine whether, regeneration is being required in at least one of the first leg or the second leg based on operating parameters of the first leg and the second leg, and whether regeneration is inhibited in either the first leg or the second leg; and in response to determining that (i) regeneration is required in at least one of the first leg or the second leg, and (ii) regeneration is not inhibited in either the first leg or the second leg, cause insertion of hydrocarbons into the engine to thereby increase the temperature of the exhaust gas to a target temperature and cause regeneration in each of the first leg and the second leg.

In some embodiments, a method for controlling regeneration of at least one of a SCR catalyst or a filter included in a first leg or a second leg of an aftertreatment system, the first leg structured to receive a first portion of an exhaust gas produced by an engine, and the second leg structured to receive a second portion of the exhaust gas, comprises: determining, by a controller coupled to each of the first leg and the second leg of the aftertreatment system, whether regeneration is permitted by the engine based on engine operating parameters; in response to determining, by the controller, that regeneration is permitted by the engine, determining, by the controller, whether regeneration is required in at least one of the first leg or the second leg based on operating parameters of the first leg and the second leg, and whether regeneration is inhibited in either the first leg or the second leg; and in response to determining, by the controller, that (i) regeneration is required in at least one of the first leg or the second leg, and (ii) regeneration is not inhibited in either the first leg or the second leg, causing insertion of hydrocarbons, by the controller, into the engine to thereby increase the temperature of the exhaust gas to a target temperature and cause regeneration in each of the first leg and the second leg.

DETAILED DESCRIPTION

Embodiments described herein relate generally to systems and methods for controlling regeneration in aftertreatment systems that include a first leg and a second leg, and in particular, to aftertreatment systems that include a controller configured to determine whether regeneration is required by a SCR catalyst and/or a filter disposed in in either of the first leg or the second leg of the aftertreatment system, and initiate regeneration in each of the first leg and the second leg to cause regeneration in each leg when one of the leg requests regeneration, and stop regeneration once each leg has completed regeneration.

Some aftertreatment systems include two or more legs, each of which includes various components of the aftertreatment system. Exhaust gas generated by the engine is divided into portions that flow into each leg of the aftertreatment system. Conventional aftertreatment systems insert hydrocarbons in each of the legs of the aftertreatment system to cause regeneration of filters (i.e., heating to a temperature sufficient to remove accumulated particulate matter in the filters) and/or regeneration of SCR catalysts (i.e., heating to remove reductant deposits, particulate matter, or otherwise regain catalytic conversion efficiency) disposed in the respective legs of the aftertreatment system. While this allows independent control of regeneration in each leg, such aftertreatment systems may increase hardware requirements. For example, such aftertreatment systems generally include separate controllers for controlling regeneration of the legs, and separate hydrocarbon insertion assemblies for inserting hydrocarbons in the legs, increasing manufacturing cost and complexity

In contrast, aftertreatment system describes herein achieve regeneration in each leg of the aftertreatment system by inserting hydrocarbons directly into the engine, for example, increasing the fuel to air ratio of an air/fuel mixture provided to the engine, which causes the engine to run richer and thereby increases the temperature of the exhaust gas and causes regeneration. Each leg of the aftertreatment system may require regeneration at different times, and may have different regeneration needs, but inserting hydrocarbons into the engine increases the temperature of the exhaust gas flowing into each leg, thereby causing regeneration in each of the legs of the aftertreatment system.

Embodiments of the systems and methods described herein for controlling regeneration in aftertreatment systems that include a first leg and a second leg may provide one or more benefits including, for example: (1) controlling regeneration in each leg of the aftertreatment system using a single controller, thereby reducing system complexity; (2) obviating the need for separate insertion assemblies for inserting hydrocarbons in each leg, thereby reducing manufacturing complexity and cost; (3) ensuring that regeneration occurs when any one of the leg is requesting regeneration to prevent reduction in catalytic conversion efficiency of the aftertreatment system; and (4) determining and setting target temperatures, feedback temperatures, and HC slip limits to optimize regeneration in each leg while inhibiting hydrocarbon slip.

As described herein, the term “regeneration in a leg” or variants thereof should be understood to mean regeneration of a SCR catalyst and/or a filter (e.g., diesel particulate filter (DPF)) disposed in a respective leg of the aftertreatment system.

FIG.1is a schematic illustration of an aftertreatment system100coupled to an engine10, according to an embodiment. The aftertreatment system100includes a first leg101aand a second leg101b(e.g., two banks of the aftertreatment system100), each of which is configured to receive a portion of an exhaust gas (e.g., diesel exhaust gas) produced by the engine10and treat constituents (e.g., NOX, CO, CO2) of the exhaust gas. The aftertreatment system100includes a reductant storage tank110, a reductant insertion assembly120, a hydrocarbon insertion assembly122, and a controller170. Moreover, the first leg101aincludes a SCR catalyst150a, an oxidation catalyst130a, a filter140a, and optionally an ammonia oxidation (AMOX) catalyst160a, and the second leg101bincludes a SCR catalyst150b, an oxidation catalyst130b, a filter140b, and optionally an ammonia oxidation (AMOX) catalyst160b.

The engine10may include, for example, a diesel engine, a gasoline engine, a natural gas engine, a dual fuel engine, a biodiesel engine, an E-85 engine, or any other suitable engine. The engine10combusts fuel and generates an exhaust gas that includes NOX, CO, CO2, and other constituents. An engine controller20may be communicatively coupled to engine10. The engine controller20is configured to receive information from an engine sensor24to determine various engine parameters and control operations of the engine10(e.g., adjust engine speed, engine torque, operate engine in lean operation mode or rich operation mode, cause insertion of hydrocarbons in engine10, etc.). Such engine parameters may include at least one of, but not limited to, an engine coolant temperature of a coolant of the engine10, an exhaust gas mass flow rate of an exhaust gas generated by the engine10, an engine torque of the engine10, an engine speed of the engine10, or an engine failure signal (e.g., an engine fault code) associated with the engine10. While shown as being a single sensor, the engine sensor24may include a set of engine sensors, each of which is configured to measure one or more of the engine parameters. In some embodiments, a hydrocarbon insertion assembly122may be coupled to the engine10and configured to insert hydrocarbons into the engine10to adjust temperature of the exhaust gas being generated by the engine10based on a signal received from the controller170. In some embodiments, the hydrocarbon insertion assembly122may also be configured to insert hydrocarbons into the aftertreatment system100upstream of the oxidation catalyst130, for example, to also assist in increasing the temperature of the exhaust gas.

The legs101a/bmay include a housing within which components of the aftertreatment system100are disposed. The housing may be formed from a rigid, heat-resistant and corrosion-resistant material, for example, stainless steel, iron, aluminum, metals, ceramics, or any other suitable material. The housing may have any suitable cross-section, for example, circular, square, rectangular, oval, elliptical, polygonal, or any other suitable shape.

An inlet conduit102is fluidly coupled to an exhaust of the engine10and configured to receive exhaust gas from the engine and divide the exhaust gas into a first portion delivered to the first leg101aand a second portion delivered to the second leg101b. Furthermore, an outlet conduit104amay be coupled to an outlet of the housing of the first leg101aand an outlet conduit104bmay be coupled to an outlet of the housing of the second leg101b, and structured to expel treated first and second portions of the exhaust gas into the environment (e.g., treated to remove particulate matter such as soot by the filters140a/band/or reduce constituents of the exhaust gas such as NOx gases, CO, unburnt hydrocarbons, etc. included in the exhaust gas by the SCR catalysts150a/band the oxidation catalysts130a/b).

A first sensor103may be positioned in the inlet conduit102. The first sensor103may comprise a NOx sensor configured to measure an amount of NOx gases included in the exhaust gas flowing into the legs101a/b, and may include a physical sensor and/or a virtual sensor. In various embodiments, a temperature sensor, a pressure sensor, an oxygen sensor or any other sensor may also be positioned in the inlet conduit102so as to determine one or more operational parameters of the exhaust gas flowing through the aftertreatment system100.

A first oxidation catalyst inlet temperature sensor106ais disposed at the inlet of the oxidation catalyst130aof the first leg101a, and a second oxidation catalyst inlet temperature sensor106bis disposed at the inlet of the oxidation catalyst130bof the second leg101b, and are configured to measure a feedback temperature at the inlet of the oxidation catalysts130a/b, respectively. The controller170may utilize the temperature of the exhaust gas provided to the oxidation catalysts130a/bto determine an amount of heat energy needed (e.g., associated with a quantity of hydrocarbons to dose).

In some embodiments, the controller170determines if the temperature of the exhaust gas provided to the first oxidation catalyst130ais approximately equal to the temperature of the exhaust gas provided to the second oxidation catalyst130b. If the temperatures are approximately equal, then the amount of heat energy is determined. If the temperatures are not approximately equal, then the controller170waits to determine the amount of heat energy until the temperatures are approximately equal (e.g., regardless of whether the temperatures measured by other sensors in the first leg101aare equal to corresponding sensors in the second leg101b, etc.).

A second sensor105a/bmay be positioned in the outlet conduit104a/bof each leg101a/b. The second sensors105a/bmay comprise second NOx sensors configured to determine an amount of NOx gases expelled into the environment after passing through the SCR catalysts150a/b. In other embodiments, the second sensors105a/bmay comprise a particulate matter sensor configured to determine an amount of particulate matter (e.g., soot included in the exhaust gas exiting the filters140a/b) in the exhaust gas being expelled into the environment. In still other embodiments, the second sensors105a/bmay comprise an ammonia sensor configured to measure an amount of ammonia in the exhaust gas flowing out of the SCR catalysts150a/b, i.e., determine the ammonia slip. This may be used as a measure of a catalytic conversion efficiency of the SCR catalysts150a/bfor adjusting an amount of reductant to be inserted into the SCR catalysts150a/b, and/or adjusting a temperature of the SCR catalysts150a/bso as to allow the SCR catalysts150a/bto effectively use the ammonia for catalytic decomposition of the NOx gases included in the exhaust gas flowing therethrough. The AMOXcatalysts160a/bmay be positioned downstream of the SCR catalysts150a/bso as to decompose any unreacted ammonia in the exhaust gas downstream of the SCR catalysts150a/b.

The oxidation catalysts130a/bmay be positioned upstream of the SCR catalysts150a/band configured to decompose unburnt hydrocarbons and/or CO included in the exhaust gas. In some embodiments, the oxidation catalysts130a/bmay include a diesel oxidation catalyst. The oxidation catalysts130a/bmay catalyze the combustion of the hydrocarbons that may be included in the exhaust gas emitted by the engine10(e.g., due to hydrocarbons being inserted by the hydrocarbon insertion assembly122into the engine10) which increases the temperature of the exhaust gas. Heating the exhaust gas may be used to regenerate the filters140a/bby burning off particulate matter that may have accumulated on the filters140a/b, and/or regenerate the SCR catalysts150a/bby evaporating reductant deposits deposited on the SCR catalysts150a/b. A first oxidation catalyst outlet temperature sensor109ais disposed at the outlet of the oxidation catalyst130aof the first leg101a, and a second oxidation catalyst outlet temperature sensor109bis disposed at the outlet of the oxidation catalyst130bof the second leg101b, and are configured to measure a feedback temperature at the outlet of the oxidation catalysts130a/b, respectively. The first oxidation catalyst outlet temperature sensor109aalso functions to measure a feedback temperature at an inlet of the first filter140a, and the second oxidation catalyst outlet temperature sensor109balso functions to measure a feedback temperature at an inlet of the second filter140b.

The filters140a/bare disposed downstream of the corresponding oxidation catalysts130a/band upstream of the SCR catalysts150a/band configured to remove particulate matter (e.g., soot, debris, inorganic particles, etc.) from the exhaust gas. In various embodiments, the filters140a/bmay include a ceramic filter. In some embodiments, the filters140a/bmay include a cordierite filter which can, for example, be an asymmetric filter. In yet other embodiments, the filters140a/bmay be catalyzed. In some embodiments, pressure sensors107a/bmay be disposed at an outlet of the corresponding filters140a/band configured to measure a filter outlet pressure at an outlet of the filters140a/b. In other embodiments, the pressure sensors107a/bmay include a differential pressure sensor disposed across the filters140a/band configured to measure a differential pressure across the filters140a/b. The filter outlet pressure or differential pressure may be indicative of a plugging of the filters140a/band/or the SCR catalysts150a/b.

The SCR catalysts150a/bis formulated to decompose constituents of an exhaust gas flowing therethrough in the presence of a reductant, as described herein. In some embodiments, the SCR catalysts150a/bmay include a selective catalytic reduction filter (SCRF). Any suitable SCR catalyst150aor150bmay be used such as, for example, platinum, palladium, rhodium, cerium, iron, manganese, copper, vanadium based catalyst, any other suitable catalyst, or a combination thereof. The SCR catalysts150a/bmay be disposed on a suitable substrate such as, for example, a ceramic (e.g., cordierite) or metallic (e.g., kanthal) monolith core which can, for example, define a honeycomb structure. A washcoat can also be used as a carrier material for the SCR catalysts150a/b. Such washcoat materials may comprise, for example, aluminum oxide, titanium dioxide, silicon dioxide, any other suitable washcoat material, or a combination thereof.

AlthoughFIG.1, shows each of the first leg101aand the second leg101bas including only the oxidation catalysts130a/b, the filters140a/b, the SCR catalysts150a/band the AMOXcatalysts160a/b, in other embodiments, a plurality of aftertreatment components may be included in each leg101a/bin addition to the oxidation catalysts130a/b, the filters140a/b, the SCR catalysts150a/band the AMOXcatalysts160a/b. Such aftertreatment components may comprise, for example, mixers, baffle plates, secondary filters (e.g., a secondary partial flow or catalyzed filter) or any other suitable aftertreatment component.

Reductant ports156a/bmay be positioned on a sidewall of the housing of each of the legs101a/band structured to allow insertion of a reductant therethrough into the internal volume defined by the housing of each of the legs101a/b. The reductant ports156a/bmay be positioned upstream of the SCR catalysts150a/b(e.g., to allow reductant to be inserted into the exhaust gas upstream of the SCR catalysts150a/b) or over the SCR catalysts150a/b(e.g., to allow reductant to be inserted directly on the SCR catalysts150a/b). In other embodiments, the reductant ports156a/bmay be disposed on the inlet conduit102and configured to insert the reductant into the inlet conduit102upstream of the SCR catalysts150a/b. In such embodiments, mixers, baffles, vanes or other structures may be positioned in the inlet conduit102so as to facilitate mixing of the reductant with the exhaust gas.

The reductant storage tank110is structured to store a reductant. The reductant is formulated to facilitate decomposition of the constituents of the exhaust gas (e.g., NOx gases included in the exhaust gas). Any suitable reductant may be used. In some embodiments, the exhaust gas comprises a diesel exhaust gas and the reductant comprises a diesel exhaust fluid. For example, the diesel exhaust fluid may comprise urea, an aqueous solution of urea, or any other fluid that comprises ammonia, by-products, or any other diesel exhaust fluid as is known in the arts (e.g., the diesel exhaust fluid marketed under the name) ADBLUE®. For example, the reductant may comprise an aqueous urea solution having a particular ratio of urea to water. In some embodiments, the reductant can comprise an aqueous urea solution including 32.5% by weight of urea and 67.5% by weight of deionized water, including 40% by weight of urea and 60% by weight of deionized water, or any other suitable ratio of urea to deionized water

A reductant insertion assembly120is fluidly coupled to the reductant storage tank110. The reductant insertion assembly120is configured to selectively insert the reductant into the SCR catalyst150a/bor upstream thereof (e.g., into the inlet conduit102) or a mixer (not shown) positioned upstream of the SCR catalysts150a/b. The reductant insertion assembly120may comprise various structures to facilitate receipt of the reductant from the reductant storage tank110and delivery to the SCR catalysts150a/b, for example, pumps, valves, screens, filters, etc.

The aftertreatment system100may also comprise a reductant injector fluidly coupled to the reductant insertion assembly120and configured to insert the reductant (e.g., a combined flow of reductant and compressed air) into the SCR catalysts150a/b. In various embodiments, the reductant injector may comprise a nozzle having predetermined diameter. In various embodiments, the reductant injector may be positioned in the reductant port156and structured to deliver a stream or a jet of the reductant into the legs101a/bso as to deliver the reductant to the SCR catalysts150a/b.

The controller170is operatively coupled to the reductant insertion assembly120, the hydrocarbon insertion assembly122, the first sensor103, the second sensors105a/b, pressure sensors107a/b, the oxidation catalyst outlet temperature sensors109a/b, and the engine controller20. The controller170is coupled to the various sensors included in each of the first leg101aand the second leg101bto determine operating parameters of the first leg101aand the second leg101b. For example, the controller170may be communicatively coupled to the first sensor103and may be configured to receive a first sensor signal from the first sensor103, for example, to determine an amount of NOx gases included in the exhaust gas entering the aftertreatment system100, an oxidation catalyst inlet temperature at inlet of the oxidation catalysts130a/bor other parameters of the exhaust gas or the aftertreatment system100. The controller170may also be communicatively coupled to the second sensors105a/band may be configured to determine a concentration of NOx gases or ammonia included in the exhaust gas being expelled into the environment or other parameters of the exhaust gas.

The controller170may be configured to determine the SCR catalytic conversion efficiencies of the SCR catalysts150a/bbased on the inlet NOx amount of NOx gases entering the aftertreatment system100, and the outlet NOx amount of NOx gases exiting the first leg101aand the second leg101b, respectively. For example, the controller170may determine a difference between the inlet NOx amount and the outlet NOx amount and determine the SCR catalytic conversion efficiency of the SCR catalysts150a/bbased on the difference, and based on SCR catalytic conversion efficiency, determine if the SCR catalysts150a/brequire regeneration (e.g., need to be regenerated due to clogging by reductant deposits, or degeneration of a catalyst active material). The controller170may also be coupled to the pressure sensors107a/bto receive a pressure signal (e.g., corresponding a filter outlet pressure or a differential pressure across the filters140a/b) and determine whether the filter140aor140brequires regeneration (e.g., needs to be regenerated to unplug or unclog the filter140a/b). The controller170may also be coupled to oxidation catalyst outlet temperature sensors109a/bto determine feedback temperatures at the outlet of the oxidation catalysts130a/b, which may be used by the controller170to set target temperatures for causing regeneration in each of the legs101a/b.

The controller170may be operably coupled to the engine controller20, the first sensor103, the second sensors105a/b, the pressure sensors107a/b, the oxidation catalyst outlet temperature sensors109a/b, the reductant insertion assembly120, the hydrocarbon insertion assembly122and various components of the aftertreatment system100using any type and any number of wired or wireless connections. For example, a wired connection may include a serial cable, a fiber optic cable, a CAT5 cable, or any other form of wired connection. Wireless connections may include the Internet, Wi-Fi, cellular, radio, Bluetooth, ZigBee, etc. In one embodiment, a controller area network (CAN) bus provides the exchange of signals, information, and/or data. The CAN bus includes any number of wired and wireless connections.

As shown inFIG.1, exhaust gas emitted from the engine splits into a first portion that flows into the first leg101a, and a second portion that flows into the second leg101b. In conventional aftertreatment systems, hydrocarbons are independently inserted into each leg of an aftertreatment system to independently regenerate each leg of such aftertreatment systems as needed. In contrast, the hydrocarbon insertion assembly122is configured to insert hydrocarbons directly into the engine10, which would cause increase in the temperature of the exhaust gas emitted by the engine10, and thereby the first and second exhaust gas portions causing an increase in each of the legs101a/bof the aftertreatment system100. The controller170is configured to trigger or initiate regeneration based on operating conditions of each of the first leg101aand the second leg101b.

Expanding further, the controller170is configured to determine whether regeneration is permitted by the engine10based on engine operating parameters. For example, the controller170may receive engine operating parameters from the engine controller20, which may be measured by an engine sensor24. Such engine parameters may include, but are not limited to engine coolant temperature of a coolant of the engine10, an exhaust gas mass flow rate of an exhaust gas generated by the engine10, an engine torque of the engine10, an engine speed of the engine10, or an engine failure signal (e.g., an engine fault code) associated with the engine10, any other suitable parameter or a combination thereof. For example, there may be certain conditions under which the engine10may not be able to perform regeneration (e.g., too high a torque or load on the engine, engine idling, too little fuel, or engine operating parameters being outside established thresholds, etc.). If the controller170determines that regeneration is not permitted by the engine10, for example, based on a signal received from the engine controller20, the controller170may abort regeneration.

In response to determining that regeneration is permitted by the engine10, the controller170determines whether regeneration is required by at least one of the first leg101aor the second leg101bbased on operating parameters of the first leg101aand the second leg101b, respectively, and whether regeneration is inhibited in either the first leg101aor the second leg101b, for example, based also on the operating parameters of the first leg101aand the second leg101b. The operating parameters of the legs101a/bmay include a pressure at the outlet of the filters140a/bor across the filters140a/b, NOx conversion efficiency at the second sensor105a/b, or SCR catalysts150a/btemperature, status of the various sensors included in the aftertreatment system100, etc. In the present specification, the phrase “regeneration is required” or variants thereof means that a threshold condition has been satisfied which indicates that at least one of the SCR catalyst150aor150b, or at least one of the filters140aor140bwould benefit from regeneration.

In some embodiments, regeneration may be inhibited in the first leg101aand/or the second leg101b. For example, the filters140a/bor SCR catalysts150a/bmay have already failed, sensors105a/b,107a/b,109a/b, or other sensors included in the aftertreatment system100may have malfunctioned, the hydrocarbon insertion assembly122or components thereof have malfunctioned, the reductant insertion assembly120or components thereof have malfunctioned, or there might be other operating conditions that inhibit regeneration (e.g., because of possibility of damage to aftertreatment components of the first leg101aand/or second leg101b, or NOx emissions exceeding allowable thresholds). In this situation, the controller170aborts regeneration.

On the contrary, if the controller170determines that (i) at least one of the first leg101aor the second leg101brequires regeneration, and (ii) regeneration is not inhibited in either the first leg101aor the second leg101b, the controller170is configured to cause insertion of hydrocarbons into the engine10to thereby increase the temperature of the exhaust gas to a target temperature and cause regeneration in each of the first leg101aand the second leg101b. That is once the controller170determines that one of the first leg101aor the second leg101brequires regeneration, the controller170may cause activation of the hydrocarbon insertion assembly122to insert hydrocarbons into the engine10(e.g., to cause the engine10to run rich and emit heated exhaust gas). Thus, regeneration is initiated in each of the legs101aand101b, even if only one of the legs101a/bis requesting regeneration.

The controller170monitors a regeneration stage of each of the first leg101aand the second leg101bduring regeneration, for example, based on feedback temperatures received from the first sensor103, the oxidation catalyst outlet temperature sensor109a, or temperature signals received from any temperature sensor configured to measure temperature of the SCR catalysts150a/b. For example,FIG.7Ashows various regeneration stages of the aftertreatment system100in which both the first leg101aand the second leg101bexperience the same regeneration stages at various time points (indicated on the x-axis as x1, x2, x3, x4, and x5).

The regeneration stages may include a warmup stage where a temperature of legs101a/bis increased to a warm up temperature (e.g., 400-450 degrees Celsius for regeneration of a filter, 325-450 degrees Celsius for regeneration of a SCR catalyst), a plateau stage which occurs after the warmup stage and at which the temperature is held at the warmup temperature for a predetermined time period (e.g., 30-60 seconds for regeneration of a filter, 20-60 seconds for regeneration of a SCR catalyst), and a target regeneration stage which occurs after the plateau stage and at which the temperature of the aftertreatment system100is increased to the target temperature (e.g., 500-575 degrees Celsius for regeneration of a filter, 350-575 degrees Celsius for regeneration of a SCR catalyst). The regeneration stages also include a regen stage which occurs after the target regeneration stage at which the temperature of the legs101aand101bis held at or above (e.g., within ±10%) the target temperature to cause regeneration in each of the legs101a/b. The regeneration stage also includes a conditioning stage which occurs after the target regeneration stage in which the temperature of the legs101a/bis decreased to an initial temperature of the legs101a/b, i.e., the temperature of the legs101a/bbefore the warmup stage was started.FIG.8Aalso shows another scenario in which the first leg101and the second leg101bexperience different regeneration stages at different times.

The controller170is configured to determine if regeneration is complete in each of the first leg101aand the second leg101b. Once the controller170determines that regeneration is complete in each of the first leg101aand the second leg101b, the controller170stops causing insertion of hydrocarbons into the engine10to stop regeneration in each of the first leg101aand the second leg101b.

The first leg101aand the second leg101bmay require different regeneration that corresponds to different target temperatures at which the regeneration for that leg should be performed. For example, the controller170may determine based on the operating parameters of the first leg101athat the first leg101ais requires regeneration of the SCR catalyst150awhich may correspond to a first target temperature (e.g., 450-500 degrees Celsius, 400-450 degrees Celsius). In contrast, the controller170may determine based on the operating parameters of the second leg101bthat the second leg101brequires regeneration of the filter140bwhich may correspond to a second target temperature (e.g., 525-575 degrees Celsius, 450-575 degrees Celsius), which may be smaller or otherwise different from the first target temperature. Thus, regeneration in each of the legs101a/bmay demand a different target temperature for meeting its regeneration demand. Moreover, as shown inFIG.8A, each of the first leg101aand the second leg101bmay experience different regeneration stages at different time points, and therefore, the target temperature of the first leg101amay be different from the target temperature of the second leg101b.

For example, if both the first leg101aand the second leg101bare used in regeneration of a filter, then the first target temperature may be 450-500 degrees Celsius and the second target temperature may be 525-575 degrees Celsius. In another example, if both the first leg101aand the second leg101bare used in regeneration of a filter, the first target temperature may be 400-450 degrees Celsius and the second target temperature may be 450-575 degrees Celsius. Such an example may be useful where the second leg101bis finishing its plateau stage and the first leg101ais ready to move on from the plateau stage.

The controller170is configured to set a target temperature for controlling regeneration based on the target temperatures of each of the first leg101aand the second leg101b. For example, the controller170may monitor a regeneration stage of each of the first leg101aand the second leg101b. In response to each of the first leg101aand the second leg101bbeing at a regeneration stage that corresponds to the plateau stage or a regeneration stage that occurs after the plateau stage, the controller170is configured to set the target temperature as the smaller of the first target temperature of the first leg101aand the second target temperature of the second leg101b. For example, if a second target temperature of the second leg101bis less than a first target temperature of the first leg101a, the controller sets the target temperature as the second target temperature.

However, in response to one of the first leg101aor the second leg101bbeing at a regeneration stage that occurs before the plateau stage and the other of the first leg101aor the second leg101bbeing at a regeneration stage that occurs after the plateau stage, the controller170is configured to cause increase of the target temperature to an adjusted target temperature. For example, the first leg101amay be at the plateau stage or at a regeneration stage that occurs after the plateau stage, and the second leg101bmay be at a regeneration stage that occurs before the plateau stage. In such instances, the controller170may be configured to increase the temperature from the smaller of the first and the second target temperature (e.g., increase the temperature above the second target temperature described in the example in the previous paragraph) to an adjusted target temperature which is greater than smaller of the first target temperature and the second temperature, for example, greater than the second target temperature, but may also be greater than the first target temperature so as to accelerate heating of the lagging leg (i.e., the one of the legs101a/bthat is behind in terms of regeneration stage) that in the particular scenario described in the previous paragraph is the second leg101b, towards the plateau stage.

The controller170may continue to monitor the regeneration stage of each of the legs101a/band determine whether the one of the first leg101aor the second leg101bwhich was at a regeneration stage that occurs before the plateau stage, has reached the plateau stage. Responsive to determining that the one of the first leg101aor the second leg101bhas reached the plateau stage, the controller170is configured to hold or maintain the target temperature at the adjusted target temperature until the plateau stage of the one of the first leg101aor the second leg101bthat was lagging behind is complete.

In response to each of the first leg101aand the second leg101bbeing at a regeneration stage that occurs after the plateau stage, or an actual temperature of each of the first leg101aand the second leg101bbeing greater than the adjusted target temperature, the controller170is configured to set the target temperature to the smaller of the first target temperature of the first leg101aand the second target temperature of the second leg101b. In contrast, even after the leg101aor101bthat was lagging behind in its regeneration stage completes the plateau but the actual temperature of both the legs101a/bis not greater than the adjusted target temperature, the controller170is configured to hold or maintain the target temperature at the adjusted target temperature until the actual temperature (i.e., feedback temperature received from temperature sensors) of both legs101a/bis greater than the adjusted target temperature. It should be appreciated that the target temperature determined and set by the controller170is not a fixed value but changes dynamically over time so as to cause the each of the legs101a/bof the aftertreatment system100to proceed through the various regeneration stages.

In some embodiments, the aftertreatment system100includes a first filter outlet temperature sensor190a. The first filter outlet temperature sensor190ais disposed at an outlet of the first filter140aand is configured to measure a feedback temperature at the outlet of the first filter140a. The first filter outlet temperature sensor190ais also configured to measure a feedback temperature at the inlet of the first SCR catalyst150a. In some embodiments, the aftertreatment system100includes a second filter outlet temperature sensor190b. The second filter outlet temperature sensor190bis disposed at an outlet of the second filter140band is configured to measure a feedback temperature at the outlet of the second filter140b. The second filter outlet temperature sensor190bis also configured to measure a feedback temperature at the inlet of the second SCR catalyst150b. The filter outlet temperature sensors190a/bare operatively coupled to the controller170. The feedback temperature(s) measured by the filter outlet temperature sensors190a/bcan be used to correct the target temperature (e.g., via a negative offset) if the feedback temperature(s) are too high (e.g., above a threshold).

In some embodiments, the aftertreatment system100includes a first SCR catalyst outlet temperature sensor191a. The first SCR catalyst outlet temperature sensor191ais disposed at an outlet of the first SCR catalyst150aand is configured to measure a feedback temperature at the outlet of the first SCR catalyst150a. The first SCR catalyst outlet temperature sensor191ais also configured to measure a feedback temperature at the inlet of the first AMOXcatalyst160a. In some embodiments, the aftertreatment system100includes a second SCR catalyst outlet temperature sensor191b. The second SCR catalyst outlet temperature sensor191bis disposed at an outlet of the second SCR catalyst150band is configured to measure a feedback temperature at the outlet of the second SCR catalyst150b. The second SCR catalyst outlet temperature sensor191bis also configured to measure a feedback temperature at the inlet of the second AMOXcatalyst160b. The SCR catalyst outlet temperature sensors191a/bare operatively coupled to the controller170. The feedback temperature(s) measured by the SCR catalyst outlet temperature sensors191a/bcan be used to correct the target temperature (e.g., via a negative offset) if the feedback temperature(s) are too high (e.g., above a threshold).

FIG.7B, which corresponds toFIG.7Ain which both the first leg101aand the second leg101bexperience the same regeneration stage at the same time, shows a first target temperature of the first leg101a, at different time points, that is higher than a target temperature of the second leg101b, at the same time points.FIG.7Cshows the final target temperature determined by the controller170at different time points, which is used to control regeneration of each of the first leg101aand the second leg101b, and the corresponding feedback temperature received from the second leg101b, which corresponds to the measured temperature of the second leg101bduring the various regeneration stages.

FIG.8B, which corresponds toFIG.8Ain which the first leg101aand the second leg101bexperience different regeneration stages at different times, shows plots of the first target temperature for the first leg101aand the second target temperature for the second leg101bat various regeneration stages of each leg101a/b.FIG.8Cis a plot of final regeneration target temperature set by the controller170for controlling regeneration in in each of the two legs101a/b. Up to time point x2 where the first leg101ais still in its plateau stage and second leg101bhas not yet started the plateau stage, the target temperature is set by the controller170as the smaller (or minimum) of the first and second target temperatures. Once the first leg101a, which is the leading leg (i.e., experiences various regeneration stages earlier than that second leg101b) enters the target stage that occurs after the regeneration stage, the controller170increases or bumps the target temperature to an adjusted target temperature (e.g., 425 degrees Celsius as shown inFIG.8Cbut could be any other adjusted target temperature), and holds the target temperature at the adjusted target temperature until both legs101a/bexit the target stage, and each of the first leg feedback temperature and the second leg feedback temperature are greater than the adjusted target temperature. The controller170then sets the target temperature to be the smaller of the first target temperature and the second target temperature.

While the controller170receives feedback temperatures from both legs101a/b, for example, the oxidation catalyst outlet temperature from the oxidation catalyst outlet temperatures sensors109a/b, which the controller170uses to control or monitor regeneration in each of the legs101a/b, in some instances the oxidation catalyst outlet temperatures received from the first leg101aand the second leg101bmay be different. The controller170is configured to determine a feedback temperature for controlling regeneration based on each of a first feedback temperature received from the first leg101a(e.g., a first oxidation catalyst outlet temperature received from the oxidation catalyst outlet temperature sensor109a), and a second feedback temperature received from the second leg101b(e.g., a second oxidation catalyst outlet temperature received from the second oxidation catalyst outlet temperature sensor109b).

For example, the controller170may be configured to receive the first feedback temperature signal from the first leg101aand a second feedback temperature from the second leg101bto determine the first feedback temperature of the first leg101aand a second feedback temperature of the second leg101b, respectively. In response to determining that each of the first leg101aand the second leg101bis at a regeneration stage that occurs before their respective target regeneration stages, the controller170is configured to use a larger of the first feedback temperature and the second feedback temperature to control an amount of hydrocarbons inserted into the engine10to cause increase the temperature of the exhaust gas to the target temperature.

On the other hand, if the controller determines that (i) at least one of the first leg101aor the second leg101bis at its target regeneration stage or at a regeneration stage that occurs after the target regeneration stage, and (ii) neither of the first feedback temperature or the second feedback temperature remains above the target temperature for a first time period (e.g., 20-30 seconds), the controller170is configured to use an average of the first feedback temperature and the second feedback temperature to control the amount of hydrocarbons inserted into the engine10to cause increase of the temperature of the exhaust gas to the target temperature.

In some embodiments, the controller170incorporates a temperature control that can cut the first time period short when a temperature of the first leg101aor the second leg101bis above a threshold temperature. The amount of hydrocarbons inserted into the engine10can be controlled based upon the comparison between the temperature and the threshold temperature. For example, more hydrocarbons can be inserted when the difference between the feedback temperature and the target threshold temperature is greater. Conversely, less hydrocarbons are inserted when the first oxidation catalyst outlet temperature or the second oxidation catalyst outlet temperature is too high above the target temperature.

However, if the controller determines that (i) at least one of the first leg101aor the second leg101bis at the target regeneration stage or is at a regeneration stage that occurs after the target regeneration stage, and (ii) one of the first feedback temperature or the second feedback temperature remains above the target temperature for a first time period, the controller170is configured to determine and use a weighted average of the first feedback temperature and the second feedback temperature to control the amount of hydrocarbons inserted into the engine10to cause increase of the temperature of the exhaust gas to the target temperature.

FIG.9shows a plot of final feedback temperature determined by the controller170based on first leg feedback temperature and the second leg feedback temperature. Up to time point x2 when both legs are at a regeneration stage that occurs before the target regeneration stage, the greater or maximum of the first leg feedback temperature and the second leg feedback temperature is used by the controller170to control regeneration. Once one of the first leg101aor the second leg101bis at the target regeneration stage or at a regeneration stage that occurs after the target regeneration stage, the controller170uses an average of the first and second leg feedback temperatures (indicated is 50/50 weight inFIG.9) to control regeneration. Once the controller170determines that the first leg feedback temperature remains above the target temperature for a first time period, the controller170determines and uses a weighted average of the first and second leg feedback temperatures to control regeneration. For example, in this scenario, the weighted average is biased or weighted towards the first leg feedback temperature because the first leg101ais hotter than the second leg101b. Weighting or biasing towards the hotter leg prevents one of the first leg101aor the second leg101bto get too hot which can damage the hotter leg.

The controller170is configured to determine a hydrocarbon dosing quantity (or feed forward amount of hydrocarbons to be dosed) that should be inserted into the engine10achieve the target temperature based on a final oxidation catalyst outlet target temperature that may correspond to the target temperature, the total exhaust gas flow rate, average oxidation catalyst inlet temperatures of the oxidation catalysts130a/b(e.g., measured by the first sensor103or another temperature sensor disposed at an inlet of each of the oxidation catalysts130a/b), and average of the expected thermal efficiencies of the filters140a/b. The final oxidation catalyst outlet target temperature may be determined by the controller170as previously described herein. While the determined hydrocarbon dosing quantity is based on the target temperature, the actual temperature (i.e., feedback temperature) of each of the legs101a/bmay be different from the target temperature. The controller170is configured to also determine an estimated hydrocarbon dosing quantity based on the determined amount of hydrocarbons to be inserted based on the desired target temperature, and the feedback temperature of each leg [e.g., a proportional-integral-derivative (PID) quantity determined using a PID or feedback portion of the controller170].

Too much hydrocarbon dosing, however, can cause some of the hydrocarbons to slip downstream of the oxidation catalysts130a/bunburnt which is undesirable. Thus, the first leg101ahas a first hydrocarbon slip limit or first HC slip limit, which corresponds to the maximum amount of hydrocarbons that can be inserted into the first leg101awithout having HC slip based on the feedback temperature of the first leg101a, and the second leg101bhas a second HC slip limit based on the maximum amount of hydrocarbons that can be inserted into the second leg101bwithout having hydrocarbon slip based on feedback temperature of the second leg101b.

The controller170determines whether the exhaust flow rate is greater than a flow threshold. If the exhaust flow rate is less than the flow threshold, the controller170continues to monitor the exhaust flow rate. Once the exhaust flow rate is greater than the flow threshold, the controller170determines the oxidation catalyst inlet temperature at the inlet of the oxidation catalyst130aincluded in the first leg101aand the oxidation catalyst130bincluded in the second leg101b. If the oxidation catalyst inlet temperature of either one of the oxidation catalysts130a/bis below its respective light-off temperature that corresponds to a minimum temperature at which the oxidation catalysts130a/bcan catalyze combustion of hydrocarbons, the controller170sets the hydrocarbon insertion amount to zero, that is hydrocarbons are not inserted into the engine10(other than those being inserted to perform normal engine operation) and regeneration is not initiated.

In response to the oxidation catalyst inlet temperature of each of the first leg101aand the second leg101bof the aftertreatment system100being greater than their respective light-off temperatures, the controller170determines whether an estimated hydrocarbon dosing quantity of the hydrocarbons to be inserted into the engine10is less than a first leg hydrocarbon slip limit of the first leg and a second leg hydrocarbon slip limit of the second leg. In response to the estimated hydrocarbon dosing quantity being less than each of the first leg hydrocarbon slip limit and the second leg hydrocarbon slip limit, the controller170sets the hydrocarbon dosing quantity of hydrocarbons to be dosed into the engine10as the estimated hydrocarbon dosing quantity.

On the other hand, in response to determining that the estimated hydrocarbon dosing quantity is greater than each of the first leg hydrocarbon slip limit and the second leg hydrocarbon slip limit, the controller170determines whether the first leg hydrocarbon slip limit is greater than the second hydrocarbon slip limit. In response to the first leg hydrocarbon slip limit being greater than the second leg hydrocarbon slip limit, the controller170sets the second leg hydrocarbon slip limit as the hydrocarbon dosing quantity, and in response to the first leg hydrocarbon slip limit being less than the second leg hydrocarbon slip limit, the controller170sets the first leg hydrocarbon slip limit as the hydrocarbon dosing quantity. Thus, the controller170always selects the smaller of the first hydrocarbon slip limit and the second hydrocarbon slip limit as the dosing quantity to prevent hydrocarbon slip limit in both legs101a/b.

FIG.10is a plot of first leg hydrocarbon slip limit of the first leg101a, and the second leg hydrocarbon slip limit of the second leg101b, the estimated hydrocarbon dosing quantity, and the final estimated dosing quantity of hydrocarbons that are inserted into the engine10. The controller170does not initiate hydrocarbon dosing until time point x1 until the oxidation catalysts130a/breach their respective light-off temperatures. The controller170then controls the HC dosing quantity such that the final HC dosing quantity always remains below the first leg HC slip limit and the second leg HC slip limit.

FIG.11is a plot of target temperature and actual or feedback temperature received from each of the first leg101aand the second leg101bas each of the legs proceed through their respective regeneration stages, as the aftertreatment system100proceeds through regeneration controlled by the controller170. As seen inFIG.11, the controller170initiates regeneration in each of the legs101a/bsimultaneously, and dynamically adjusts the target temperature such that even though regeneration may be initially out of sync between the two legs101a/b, the two legs101a/bconverge towards requesting the same target temperature.

The controller170receives temperatures from various temperature sensors. In some instances, one or more of the temperature sensors may malfunction. In such instances the controller170uses temperature signals received from other temperature sensors in lieu of the failed temperature sensor, or use a default temperature value instead. For example, if an oxidation catalyst inlet temperature sensor fails, the controller170may use an oxidation catalyst outlet temperature measured by an oxidation catalyst outlet temperature sensor (e.g., the sensor109a/b) if the oxidation catalyst outlet temperature sensor is working properly. In some embodiments, the controller170may be configured to adjust the oxidation catalyst outlet temperature based on ambient temperature, and may only adjust the oxidation catalyst outlet temperature when hydrocarbons are not being inserted into the oxidation catalyst130a/b. However, if the oxidation catalyst outlet temperature sensor also has errors, the controller170may use a default oxidation catalyst inlet temperature value stored in a memory of the controller170instead.

If an oxidation catalyst outlet temperature sensor fails but an oxidation catalyst inlet temperature sensor (e.g., the first sensor103) is working properly, the controller170may use an oxidation catalyst inlet temperature measured by the oxidation catalyst inlet temperature sensor, or a filter outlet temperature at an outlet of the filter140a/b, which may be adjusted based on ambient temperature if the filter outlet temperature is working properly. However, if the oxidation catalyst inlet temperature sensor and the filter outlet temperature sensor have errors, the controller170may use a default oxidation catalyst outlet temperature value stored in a memory of the controller170instead.

If a filter outlet temperature sensor fails but an oxidation catalyst outlet temperature sensor (e.g., the sensor109a/b) is working properly, the controller170may use an oxidation catalyst outlet temperature measured by the oxidation catalyst outlet temperature sensor. However, if the oxidation catalyst outlet temperature sensor also has errors, the controller170may use a default filter outlet temperature value stored in a memory of the controller170instead.

Generally, the controller170may be configured to determine an SCR inlet temperature at an inlet of the SCR catalysts150a/bbased on a weighted average between a filter outlet temperature measured by a filter outlet temperature sensor, and a SCR inlet temperature measured by a SCR inlet temperature sensor. If the filter outlet temperature sensor fails, the controller170may use the SCR inlet temperature alone without calculating the weighted average.

If an SCR outlet temperature sensor fails, the controller170may be configured to use a default SCR outlet temperature value in lieu of the measured SCR outlet temperature.

In some embodiments, the controller170includes various circuitries or modules configured to perform the operations of the controller170described herein. For example,FIG.2shows a block diagram of the controller170, according to an embodiment. The controller170may include a processor172, a memory174, or any other computer readable medium, and a communication interface176. Furthermore, the controller170includes a regeneration request determination module174a, a regeneration trigger control module174b, a target temperature determination module174c, a feedback temperature determination module174d, a HC dosing estimation module174e, and a HC slip limit determination module174f. It should be understood thatFIG.2shows only one embodiment of the controller170and any other controller capable of performing the operations described herein can be used.

The processor172can comprise a microprocessor, programmable logic controller (PLC) chip, an ASIC chip, or any other suitable processor. The processor172is in communication with the memory174and configured to execute instructions, algorithms, commands, or otherwise programs stored in the memory174.

The memory174comprises any of the memory and/or storage components discussed herein. For example, memory174may comprise a RAM and/or cache of processor172. The memory174may also comprise one or more storage devices (e.g., hard drives, flash drives, computer readable media, etc.) either local or remote to controller170. The memory174is configured to store look up tables, algorithms, or instructions, for example, for controlling regeneration.

In one configuration, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fare embodied as machine or computer-readable media (e.g., stored in the memory174) that is executable by a processor, such as the processor172. As described herein and amongst other uses, the machine-readable media (e.g., the memory174) facilitates performance of certain operations of the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fto enable reception and transmission of data. For example, the machine-readable media may provide an instruction (e.g., command, etc.) to, e.g., acquire data. In this regard, the machine-readable media may include programmable logic that defines the frequency of acquisition of the data (or, transmission of the data). Thus, the computer readable media may include code, which may be written in any programming language including, but not limited to, Java or the like and any conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program code may be executed on one processor or multiple remote processors. In the latter scenario, the remote processors may be connected to each other through any type of network (e.g., CAN bus, etc.).

In another configuration, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fare embodied as hardware units, such as electronic control units. As such, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fmay be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc.

In some embodiments, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fmay take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of “circuit.” In this regard, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fmay include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on.

Thus, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fmay also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. In this regard, the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fmay include one or more memory devices for storing instructions that are executable by the processor(s) of the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174f. The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory174and the processor172.

In the example shown, the controller170includes the processor172and the memory174. The processor172and the memory174may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fThus, the depicted configuration represents the aforementioned arrangement in which the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fare embodied as machine or computer-readable media. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments such as the aforementioned embodiment where the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174f, or at least one circuit of the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174fare configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure.

The processor172may be implemented as one or more general-purpose processors, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital signal processor (DSP), a group of processing components, or other suitable electronic processing components. In some embodiments, the one or more processors may be shared by multiple circuits (e.g., the regeneration request determination module174a, the regeneration trigger control module174b, the target temperature determination module174c, the feedback temperature determination module174d, the HC dosing estimation module174e, and the HC slip limit determination module174f) may comprise or otherwise share the same processor which, in some example embodiments, may execute instructions stored, or otherwise accessed, via different areas of memory. Alternatively or additionally, the one or more processors may be structured to perform or otherwise execute certain operations independent of one or more co-processors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure. The memory174(e.g., RAM, ROM, Flash Memory, hard disk storage, etc.) may store data and/or computer code for facilitating the various processes described herein. The memory174may be communicably connected to the processor172to provide computer code or instructions to the processor172for executing at least some of the processes described herein. Moreover, the memory174may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory174may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.

The communication interface176may include wireless interfaces (e.g., jacks, antennas, transmitters, receivers, communication interfaces, wire terminals, etc.) for conducting data communications with various systems, devices, or networks. For example, the communication interface176may include an Ethernet card and port for sending and receiving data via an Ethernet-based communications network and/or a Wi-Fi communication interface for communicating with the first sensor103, the second sensors105a/b, the pressure sensors107a/b, the oxidation catalyst outlet temperature sensors109a/b, the reductant insertion assembly120, the hydrocarbon insertion assembly, or the engine controller20. The communication interface176may be structured to communicate via local area networks or wide area networks (e.g., the Internet, etc.) and may use a variety of communications protocols (e.g., IP, LON, Bluetooth, ZigBee, radio, cellular, near field communication, etc.).

The regeneration request determination module174ais configured to receive aftertreatment operating parameter signals from the sensors (e.g., the first sensor103, the second sensors105a/b, the pressure sensors107a/b, the oxidation catalyst outlet temperature sensors109a/b, or any other sensors) coupled to each of the first leg101aand the second leg101bto determine whether either of the first leg101aor the second leg101brequires regeneration (i.e., whether one of the filters140aor140bis clogged that creates a demand for filter140aand/or140bregeneration, or the catalytic conversion efficiency of the SCR catalyst150aor150bhas dropped below a threshold creating a demand for SCR catalyst150aand/or150bregeneration).

The regeneration trigger control module174bis configured to receive engine operating parameters signals from the engine controller20and determines whether regeneration is permitted by the engine10. If regeneration is permitted by the engine10, the controller170determines if any one of the first leg101aor the second leg101bis inhibiting regeneration based on the aftertreatment operating parameter signals, as previously described. If none of the legs101a/bis inhibiting regeneration, the engine controller20permits regeneration, and at least one of the legs101aor101bis requesting regeneration, the regeneration trigger control module174bgenerates a regen signal to initiate regeneration in both the legs101a/bas previously described.

The target temperature determination module174cis configured to determine a target temperature and dynamically adjust the target temperature based on the target temperature determined for each of the first leg101aand the second leg101b, and the regeneration stage of each leg at various time points, as previously described herein.

The feedback temperature determination module174dis configured to receive feedback temperature signals from each of the first leg101aand the second leg101b, and determine the feedback temperature to determine the target temperatures and control regeneration, as previously described.

The HC dosing estimation module174eis configured to determine an estimated HC dosing quantity based on the final target oxidation catalyst outlet temperatures of the oxidation catalysts130a/b, the exhaust flow rate of the exhaust gas emitted by the engine10, the average of the oxidation catalyst inlet temperatures of the oxidation catalysts130a/b, and an average thermal efficiency of the filters140a/b, as well as the actual or feedback temperatures, as previously described.

The HC slip limit determination module174fis configured to determine the HC slip limits of each of the first leg101aand the second leg101b, and generate a HC insertion signal to insert a quantity of hydrocarbons into the engine10to cause regeneration based on the HC slip limits of each of the legs101a/b, and the estimated HC dosing quantity, as previously described.

FIG.3is a flow charts showing a method200for initiating regeneration in an aftertreatment system (e.g., the aftertreatment system100) that includes a first leg (e.g., the first leg101a) and a second leg (e.g., the second leg101b), according to an embodiment. While described with reference to the controller170, the engine10and the aftertreatment system100, the operations of the method200can be used with any controller that is operatively coupled to any aftertreatment system that includes multiple legs, and that is coupled to any engine.

The method200includes determining by the controller170whether regeneration is permitted by the engine10based on a signal received from the engine controller20, at202. If the controller170determines that the engine10does not permit regeneration (202: NO), the method200proceeds to operation204and the controller170does not trigger or initiate regeneration. The method200then returns to operation202.

If the controller170determines that engine10permits regeneration (202: YES), the controller170determines whether regeneration is requires by at least one of the first leg101aor the second leg101bbased on operating parameters of the first leg101aand the second leg101b, and whether regeneration is inhibited in either the first leg101aor the second leg101b, at206. If the controller170determines neither of the legs101a/brequires regeneration, or if at least one of the legs101aor101brequires regeneration, but one of the legs101a/bis inhibiting regeneration (206: NO), the method200proceeds to operation204, and the controller170does not initiate regeneration.

On the other hand, if at208, the controller170determines that at least one of the legs101a/brequires regeneration and regeneration is not inhibited in either the first leg101aor the second leg101b(206: YES), the controller170initiates regeneration at208, by causing insertion of hydrocarbons (e.g., via the hydrocarbon insertion assembly122) into the engine10to increase the temperature of the exhaust gas to cause regeneration in each of the first leg101aand the second leg101b.

At208, the controller170continues to monitor a regeneration stage of each of the first leg101aand the second leg101b. At212, the controller170determines if regeneration is complete in each of the first leg101aand the second leg101b. If the controller170determines that regeneration is not complete in at least one of the first leg101aor the second leg101b(212: NO), the method200returns to operation210, and the controller170continues to monitor the regeneration stage of each of the legs101a/b. On the other hand, once the controller170determines that regeneration is complete in each of the first leg101aand the second leg101b, the controller170stops regeneration, at214.

FIG.4is a schematic flow diagram of a method300for determining and setting a target temperature to which the legs101a/bare heated in the method ofFIG.3, according to an embodiment. The method300starts after regeneration is active, triggered or initiated by the controller170. At302, the controller170determines whether each of the first leg101aand the second leg101bis at a regeneration stage that occurs before the plateau stage. If the controller170determines that each of the legs101a/bis at a regeneration stage that occurs before below the plateau stage, i.e., have not yet reached the plateau stage, (302: YES), the controller170sets the target temperature as the smaller of a first target temperature of the first leg101aand a second target temperature of the second leg101b.

If the controller determines that both legs101a/bare not at a regeneration stage that occurs before the plateau stage (302: NO), the controller170determines whether one of the first leg101aor the second leg101bis at a regeneration stage that occurs before the plateau stage, and the other of the first leg101aor the second leg101bis at a regeneration stage that occurs after the plateau stage, at306. In response to the one of the first leg101aor the second leg101bbeing at a regeneration stage that occurs before the plateau stage, and the other of the first leg101aor the second leg101bbeing at a regeneration stage that occurs after the plateau stage (306: YES), the method proceeds to operation308and the controller170causes increase of the target temperature to an adjusted target temperature that is greater than the smaller of a first target temperature of the first leg101aand a second target temperature of the second leg101b.

At310, the controller170determines whether the lagging leg, i.e., the one of the first leg101aor the second leg101bwhich was at a regeneration stage that occurs before plateau stage, has reached its plateau stage. If the controller170determines that the lagging leg has not reached its plateau stage (310: NO), the method returns to operation308and the controller170continues to increase the target temperature to the adjusted target temperature (e.g., continue to increase the adjusted target temperature). Responsive to determining that the one of the first leg101aor the second leg101bhas reached its plateau stage (310: YES), the controller170causes maintaining of the target temperature at the adjusted target temperature, at312.

At314, the controller170determines whether the lagging leg of the legs101a/bhas completed its plateau stage. If the controller170determines that the lagging leg of the legs101a/bhas not completed its plateau stage (314: NO), the method returns to operation312, and the controller170continues to maintain or hold the target temperature at the adjusted target temperature. If the controller170determines that lagging leg of the legs101a/bhas completed its plateau stage (314: YES), the controller170determines if an actual or feedback temperature of both the legs101a/bis greater than the adjusted target temperature, at316. If the controller170determines that the actual temperature of at least one the first leg101aand the second leg101bis less than the adjusted target temperature (316: NO), the controller170continues to hold the target temperature at the adjusted target temperature, at318.

In response to determining that actual temperature of both of the legs101a/bis greater than the adjusted target temperature (316: YES), the controller170sets the target temperature as the smaller of the first target temperature of the first leg101aand the second target temperature of the second leg101b, at322.

If at operation306, the controller170determines that the regeneration stage in neither of the legs101a/bis less than the plateau stage (306: NO), the controller determines whether the regeneration stage is greater than the plateau stage on both legs101a/b, at320. If the controller170determines that the regeneration stage is not greater than the plateau stage on both legs (320: NO), the method300returns to operation302. On the other hand, in response to the regeneration stage of each of the first leg101aand the second leg101bbeing greater than the plateau stage (320: YES), the method300proceeds to operation322, and the controller170sets the target temperature to the smaller of the first target temperature and the second target temperature.

FIG.5is a schematic flow diagram of a method400for determining the feedback temperature that may be used for controlling regeneration performed via the method200, according to an embodiment. The method400starts after regeneration is active, triggered or initiated by the controller170. The method400includes determining whether both the first leg101aand the second leg101bis at a regeneration stage that occurs before the target stage, at402. For example, the controller170may receive a first feedback temperature signal from the first leg101aand a second feedback temperature from the second leg101bto determine a first feedback temperature of the first leg101aand a second feedback temperature of the second leg101b, respectively. The controller170may determine the regeneration stage of the first leg101abased on the first feedback temperature and the regeneration stage of the second leg101bbased on the second feedback temperature.

In response to determining, by the controller170, that each of the first leg101aand the second leg101bis 1 at a regeneration stage that occurs before a target regeneration stage of each of the first leg101aand the second leg (402: YES), the controller170uses a larger of the first feedback temperature and the second feedback temperature to control an amount of hydrocarbons inserted into the engine10to cause increase of the temperature of the exhaust gas to the target temperature, at404.

If the controller170determines that at least one of the first leg101aor the second leg101bis at the target regeneration stage or at a regeneration stage that occurs after the target regeneration stage (402: NO), the controller170determines whether at least one of the first leg101aor the second leg101bremains above the target temperature beyond a first time period, at406. If at406, the controller170determines that neither of the first feedback temperature or the second feedback temperature remains above the target temperature for the first time period (406: NO), the controller170uses an average of the first feedback temperature and the second feedback temperature to control the amount of hydrocarbons inserted into the engine10to cause increase of the temperature of the exhaust gas to the target temperature, at408. On the other hand, in response to determining, by the controller170, that one of the first feedback temperature or the second feedback temperature remains above the target temperature for the first time period, the controller170uses a weighted average of the first feedback temperature and the second feedback temperature to control the amount of hydrocarbons inserted into the engine10to cause increase of the temperature of the exhaust gas to the target temperature, at410. The weighted average may be biased towards the one of the first leg101aor the second leg101bthat has the higher feedback temperature. The method400then returns to operation402.

FIG.6is a schematic flow diagram of a method500for setting a hydrocarbon dosing quantity to prevent hydrocarbons from slipping through each of the first leg101aand the second leg101bof the aftertreatment system100during regeneration performed by the controller170via the method200, according to an embodiment. The method500starts when regeneration is active and includes determining whether an exhaust flow rate of the exhaust gas emitted by the engine10is greater than a flow threshold, at502. If the exhaust flow rate is less than the flow threshold (502: NO), the controller170sets hydrocarbon insertion to zero, at504, i.e., hydrocarbons are not inserted into the engine10. The method500then returns to operation502and the controller170continues to monitor the exhaust flow rate.

In response to determining that exhaust flow rate is greater that the flow threshold (502: YES), the controller170determines an oxidation catalyst inlet temperature at an inlet of an oxidation catalyst130a/bincluded in each of the first leg101aand the second leg101bof the aftertreatment system100, and whether the oxidation catalyst inlet temperature is less than a light-off temperature of the oxidation catalysts130a/b, at506. If the controller170determines that the oxidation catalyst inlet temperature of at least one of the oxidation catalysts130a/bis less than its respective light-off temperature (506: YES), the controller170sets hydrocarbon insertion to zero, at508, i.e., hydrocarbons are not inserted into the engine10. The method500then returns to operation506and the controller170continues to monitor the oxidation catalyst inlet temperatures of each of the oxidation catalysts130a/b.

In response to the oxidation catalyst inlet temperature of each of the first leg101aand the second leg101bof the aftertreatment system100being greater than the respective light-off temperatures thereof (506: NO), the controller170determines whether an estimated hydrocarbon dosing quantity determined by the controller170of the hydrocarbons to be inserted into the engine10is less than a first leg hydrocarbon slip limit of the first leg101aand a second leg hydrocarbon slip limit of the second leg101b, at510. In response to the estimated hydrocarbon dosing quantity being less than each of the first leg hydrocarbon slip limit and the second leg hydrocarbon slip limit (510: YES), the controller170sets the hydrocarbon dosing quantity of hydrocarbons to be dosed into the engine10as the estimated hydrocarbon dosing quantity, at512.

On the other hand, if the estimated hydrocarbon dosing quantity is greater than the hydrocarbon slip limit for both legs101a/bat510(510: NO), the controller170determines if the first leg hydrocarbon slip limit is greater than the second leg hydrocarbon slip limit, at514. In response to the first leg hydrocarbon slip limit being greater than the second leg hydrocarbon slip limit (514: YES), the controller170sets the second leg hydrocarbon slip limit as the hydrocarbon dosing quantity, at516. On the other hand, in response to the first leg hydrocarbon slip limit being less than the second leg hydrocarbon slip limit, the controller170sets the first leg hydrocarbon slip limit as the hydrocarbon dosing quantity, at518. The method500then returns to operation506.

It should be noted that the term “example” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).