TECHNICAL FIELD

[0001] The present application relates generally to aftertreatment systems, and particularly for managing mass flow split in the aftertreatment system.

BACKGROUND

[0002] Internal combustion engines, such as diesel engines, emit exhaust that includes nitrogen oxide (NOx) compounds. It may be desirable to reduce NOx emissions, for example, to comply with environmental regulations. To reduce NOx emissions, a reductant may be dosed into the exhaust by a dosing system in an aftertreatment system. The reductant cooperates with a catalyst of a catalyst member to facilitate conversion of a portion of the exhaust into non-NOx emissions, such as nitrogen (N2), carbon dioxide (CO2), and water (H2O), thereby reducing NOx emissions. In some applications, these compounds of the exhaust can be filtered or removed by one or more catalyst members (e.g., a diesel oxidation catalyst (DOC) member, a select catalytic reduction (SCR) catalyst member, diesel particulate filter (DPF) member, an ammonia oxidation (AMOx) catalyst member, etc.) located in an aftertreatment system.

SUMMARY

[0003] Certain aftertreatment systems can include multiple legs for reducing exhaust byproducts of exhaust gas generated from an internal combustion engine. Each leg within the aftertreatment system has one or more components for reducing the exhaust byproducts, such as catalyst members (e.g., SCR catalyst members, DOC members, etc.), or filters (such as DPF members). A mass flow rate of the exhaust byproducts traversing each leg can be utilized to determine ammonia (NH3) (e.g., reductant) dosage for reducing the exhaust byproducts.

[0004] However, due to certain piping restrictions or blockages within the aftertreatment system, the exhaust gas mass flow split may be uneven across the legs (e.g., flow rate of exhaust gas in one leg may differ from another). The mass flow split refers to a proportion of mass flow (or mass flow rate) split across the legs of the aftertreatment system. The restriction may be caused by a number of factors including, but are not limited to, an asymmetrical tailpipe or other improper installation of the aftertreatment system, soot load, deposit, etc. The restriction within the aftertreatment system causes an inaccuracy of mass flow rate estimation which may affect at least the reductant dosage, hydrocarbon (HC) dosage, and/or soot load estimation, etc. Consequently, the inaccurate mass flow rate estimation may lead to at least one of NH3 slip, early or delayed regeneration triggers, and/or poor regeneration control, for example. Hence, the systems, methods, and apparatuses described herein are configured to identify any restriction within the aftertreatment system and provide correction to the mass flow rate estimation, thereby adjusting at least one of reductant dosing, HC dosing, and/or soot load estimation according to the flow split to minimize reductant slip, an untimely trigger of a regeneration event, or poor regeneration control, for example.

[0005] In some embodiments, an aftertreatment system comprises a first leg comprising one or more first aftertreatment components, a second leg comprising one or more second aftertreatment components, and a controller. The controller is configured to estimate a first mass flow rate of exhaust gas in the first leg. The controller is configured to estimate a second mass flow rate of the exhaust gas in the second leg. The controller is configured to compute an estimated total mass flow rate based on the estimated first mass flow rate and the estimated second mass flow rate. In response to determining that the estimated total mass flow rate is greater than an engine exhaust mass flow rate, the controller is configured to compute a correction factor for balancing the estimated first mass flow rate and the estimated second mass flow rate. The controller is configured to estimate a corrected first mass flow rate of the exhaust gas in the first leg and a corrected second mass flow rate of the exhaust gas in the second leg using the correction factor. The controller is configured to adjust at least one of a reductant dosing, hydrocarbon dosing, or soot load estimation based on the corrected first mass flow rate and the corrected second mass flow rate.

[0006] In some embodiments, the controller is configured to regenerate at least one of a first selective catalytic reduction (SCR) catalyst of the one or more first aftertreatment components or a second SCR catalyst of the one or more second aftertreatment components in response to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate and before computing the correction factor. In some embodiments, subsequent to regenerating the at least one of the first SCR catalyst or the second SCR catalyst and before computing the correction factor, the controller is further configured to: estimate a third mass flow rate of the exhaust gas in the first leg; estimate a fourth mass flow rate of the exhaust gas in the second leg; and compute a second estimated total mass flow rate based on the third mass flow rate and the fourth mass flow rate.

[0007] In some embodiments, responsive to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate, the controller is further configured to: determine whether the first leg or the second leg is newly installed; and compute the correction factor in response to determining that the first leg or the second leg is newly installed. To compute the correction factor, the controller is configured to: determine a proportion between a first pressure differential value across a first particulate filter of the one or more first aftertreatment components and a second pressure differential value across a second particulate filter of the one or more second aftertreatment components; and compute the correction factor based on the proportion between the first pressure differential value and the second pressure differential value.

[0008] In some embodiments, responsive to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate, the controller is further configured to: determine whether the first leg or the second leg is newly installed; estimate a soot load flow rate in response to determining that neither the first leg nor the second leg is newly installed; and compute the correction factor based on the estimated soot load flow rate.

[0009] In some embodiments, the controller is further configured to estimate a first virtual mass flow rate of the exhaust gas in the first leg based on a first pressure differential value across a first particulate filter of the one or more first aftertreatment components. The controller is configured to estimate a second virtual mass flow rate of the exhaust gas in the second leg based on a second pressure differential value across a second particulate filter of the one or more second aftertreatment components. The controller is configured to compute the correction factor based on the engine exhaust mass flow rate and at least one of the estimated first virtual mass flow rate or the estimated second virtual mass flow rate.

[0010] In some embodiments, the controller is further configured to determine a first pressure differential value across a first particulate filter of the one or more first aftertreatment components and a second pressure differential value across a second particulate filter of the one or more second aftertreatment components over a time window comprising a plurality of time intervals. The controller is configured to compare, in each of the plurality of time intervals, the first pressure differential value and the second pressure differential value against a set of calibrated tables comprising a plurality of predetermined pressure differential values for different flow splits of the engine exhaust mass flow rate. The controller is configured to compute the correction factor based on the comparison between the first pressure differential value and the second pressure differential value against the set of calibrated tables at an end of the time window.

[0011] In some embodiments, to compute the correction factor, the controller is further configured to: in each of the plurality of time intervals of the time window, increment a score for one of the set of calibrated tables in response to the first pressure differential value and the second pressure differential value matching the one of the set of calibrated tables; and select, at the end of the time window, a flow split corresponding to the set of calibrated tables having a highest score to compute the correction factor.

[0012] In some embodiments, a method comprises: estimating, by a controller, a first mass flow rate of exhaust gas in a first leg comprising one or more first aftertreatment components; estimating, by the controller, a second mass flow rate of the exhaust gas in a second leg comprising one or more second aftertreatment components; computing, by the controller, an estimated total mass flow rate based on the estimated first mass flow rate and the estimated second mass flow rate; in response to determining that the estimated total mass flow rate is greater than an engine exhaust mass flow rate, computing, by the controller, a correction factor for balancing the estimated first mass flow rate and the estimated second mass flow rate; estimating, by the controller, a corrected first mass flow rate of the exhaust gas in the first leg and a corrected second mass flow rate of the exhaust gas in the second leg using the correction factor; and adjusting, by the controller, at least one of a reductant dosing, hydrocarbon dosing, or soot load estimation based on the corrected first mass flow rate and the corrected second mass flow rate.

[0013] In some embodiments, the method further comprises regenerating, by the controller, at least one of a first selective catalytic reduction (SCR) catalyst of the one or more first aftertreatment components or a second SCR catalyst of the one or more second aftertreatment components in response to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate and before computing the correction factor.

[0014] In some embodiments, subsequent to regenerating the at least one of the first SCR catalyst or the second SCR catalyst and before computing the correction factor, the method further comprises: estimating, by the controller, a third mass flow rate of the exhaust gas in the first leg; estimating, by the controller, a fourth mass flow rate of the exhaust gas in the second leg; and computing, by the controller, a second estimated total mass flow rate based on the third mass flow rate and the fourth mass flow rate.

[0015] In some embodiments, responsive to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate, the method comprises: determining, by the controller, whether the first leg or the second leg is newly installed; and computing, by the controller, the correction factor in response to determining that the first leg or the second leg is newly installed.

[0016] In some embodiments, computing the correction factor comprises: determining, by the controller, a proportion between a first pressure differential value across a first particulate filter of the one or more first aftertreatment components and a second pressure differential value across a second particulate filter of the one or more second aftertreatment components; and computing, by the controller, the correction factor based on the proportion between the first pressure differential value and the second pressure differential value.

[0017] In some embodiments, responsive to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate, the method comprises: determining, by the controller, whether the first leg or the second leg is newly installed; estimating, by the controller, a soot load flow rate in response to determining that neither the first leg nor the second leg is newly installed; and computing, by the controller, the correction factor based on the estimated soot load flow rate.

[0018] In some embodiments, the method further comprises: estimating, by the controller, a first virtual mass flow rate of the exhaust gas in the first leg based on a first pressure differential value across a first particulate filter of the one or more first aftertreatment components; estimating, by the controller, a second virtual mass flow rate of the exhaust gas in the second leg based on a second pressure differential value across a second particulate filter of the one or more second aftertreatment components; and computing, by the controller, the correction factor based on the engine exhaust mass flow rate and at least one of the estimated first virtual mass flow rate or the estimated second virtual mass flow rate.

[0019] In some embodiments, the method further comprises determining, by the controller, a first pressure differential value across a first particulate filter of the one or more first aftertreatment components and a second pressure differential value across a second particulate filter of the one or more second aftertreatment components over a time window comprising a plurality of time intervals; comparing, by the controller, in each of the plurality of time intervals, the first pressure differential value and the second pressure differential value against a set of calibrated tables comprising a plurality of predetermined pressure differential values for different flow splits of the engine exhaust mass flow rate; and computing, by the controller, the correction factor based on the comparison between the first pressure differential value and the second pressure differential value against the set of calibrated tables at an end of the time window.

[0020] In some embodiments, computing the correction factor comprises: in each of the plurality of time intervals of the time window, incrementing, by the controller, a score for one of the set of calibrated tables in response to the first pressure differential value and the second pressure differential value matching the one of the set of calibrated tables; and selecting, by the controller, at the end of the time window, a flow split corresponding to the set of calibrated tables having a highest score to compute the correction factor.

[0021] In some embodiments, an aftertreatment system comprises a first leg comprising one or more first aftertreatment components, a second leg comprising one or more second aftertreatment components, and a controller. The controller is configured to compute a first NOx conversion efficiency of the first leg. The controller is configured to compute a second NOx conversion efficiency of the second leg. The controller is configured to compute an average NOx conversion efficiency based on the first NOx conversion efficiency and the second NOx conversion efficiency. The controller is configured to compute a difference between the first NOx conversion efficiency and the second NOx conversion efficiency. In response to determining that the average NOx conversion efficiency is less than a first threshold or the difference between the first NOx conversion efficiency and the second NOx conversion efficiency is greater than the first threshold, the controller is configured to compute an adjustment factor for balancing an estimated first mass flow rate and an estimated second mass flow rate. The controller is configured to estimate an adjusted first mass flow rate of the exhaust gas in the first leg and an adjusted second mass flow rate of the exhaust gas in the second leg using the adjustment factor. The controller is configured to adjust at least one of a reductant dosing, a hydrocarbon dosing, or a soot load estimation based on the adjusted first mass flow rate and the adjusted second mass flow rate.

[0022] In some embodiments, in response to determining that the average NOx conversion efficiency is less than the first threshold or the difference between the first NOx conversion efficiency and the second NOx conversion efficiency is greater than the first threshold, the controller is further configured to: identify a low NOx conversion efficiency leg from one of the first leg or the second leg based on the computed first NOx conversion efficiency and the computed second NOx conversion efficiency. The controller is configured to determine an ammonia (NH3) to NOx ratio (ANR) of the low NOx conversion efficiency leg. The controller is configured to compare the ANR of the low NOx conversion efficiency leg to a second threshold. The controller is configured to identify a NOx slip in response to determining that the ANR of the low NOx conversion efficiency leg is less than the second threshold or an NH ₃ slip in response to determining that the ANR of the low NOx conversion efficiency leg is greater than or equal to the second threshold. The controller is configured to compute the adjustment factor to adjust a dosing rate of reductant in the aftertreatment system based on the NOx slip or the NH ₃ slip.

[0023] In some embodiments, to adjust the dosing rate of the reductant, the controller is further configured to increase the dosing rate of the reductant in the aftertreatment system by a first amount in response to the NOx slip or decrease the dosing rate of the reductant in the aftertreatment system by a second amount in response to the NH ₃ slip.

[0024] In some embodiments, the controller is further configured to compute a third NOx conversion efficiency of the low NOx conversion efficiency leg subsequent to adjusting the dosing rate of the reductant. The controller is configured to re-adjust the dosing rate of the reductant in response to determining that the third NOx conversion efficiency is less than a third threshold.

[0025] In some embodiments, the controller is configured to compute a fourth NOx conversion efficiency of the low NOx conversion efficiency leg subsequent to re-adjusting the dosing rate of the reductant. The controller is configured to trigger a fault in response to determining that the fourth NOx conversion efficiency is less than a fourth threshold.

[0026] In some embodiments, a method comprises: computing, by a controller, a first NOx conversion efficiency of a first leg comprising one or more first aftertreatment components; computing, by the controller, a second NOx conversion efficiency of a second leg comprising one or more second aftertreatment components; computing, by the controller, an average NOx conversion efficiency based on the first NOx conversion efficiency and the second NOx conversion efficiency; computing, by the controller, a difference between the first NOx conversion efficiency and the second NOx conversion efficiency; in response to determining that the average NOx conversion efficiency is less than a first threshold or the difference between the first NOx conversion efficiency and the second NOx conversion efficiency is greater than the first threshold, computing, by the controller, an adjustment factor for balancing an estimated first mass flow rate and an estimated second mass flow rate; estimating, by the controller, an adjusted first mass flow rate of the exhaust gas in the first leg and an adjusted second mass flow rate of the exhaust gas in the second leg using the adjustment factor; and adjusting, by the controller, at least one of a reductant dosing, a hydrocarbon dosing, or a soot load estimation based on the adjusted first mass flow rate and the adjusted second mass flow rate.

[0027] In some embodiments, in response to determining that the average NOx conversion efficiency is less than the first threshold or the difference between the first NOx conversion efficiency and the second NOx conversion efficiency is greater than the first threshold, the method further comprises: identifying, by the controller, a low NOx conversion efficiency leg from one of the first leg or the second leg based on the computed first NOx conversion efficiency and the computed second NOx conversion efficiency; determining, by the controller, an ammonia (NH3) to NOx ratio (ANR) of the low NOx conversion efficiency leg; comparing, by the controller, the ANR of the low NOx conversion efficiency leg to a second threshold; identifying, by the controller, a NOx slip in response to determining that the ANR of the low NOx conversion efficiency leg is less than the second threshold or an NH3 slip in response to determining that the ANR of the low NOx conversion efficiency leg is greater than or equal to the second threshold; and computing, by the controller, the adjustment factor to adjust a dosing rate of reductant in the aftertreatment system based on the NOx slip or the NH3 slip.

[0028] In some embodiments, adjusting the dosing rate of the reductant comprises: increasing, by the controller, the dosing rate of the reductant in the aftertreatment system by a first amount in response to the NOx slip or decreasing, by the controller, the dosing rate of the reductant in the aftertreatment system by a second amount in response to the NH3 slip.

[0029] In some embodiments, the method further comprises: computing, by the controller, a third NOx conversion efficiency of the low NOx conversion efficiency leg subsequent to adjusting the dosing rate of the reductant; and re-adjusting, by the controller, the dosing rate of the reductant in response to determining that the third NOx conversion efficiency is less than a third threshold.

[0030] In some embodiments, the method further comprises: computing, by the controller, a fourth NOx conversion efficiency of the low NOx conversion efficiency leg subsequent to re-adjusting the dosing rate of the reductant; and triggering, by the controller, a fault in response to determining that the fourth NOx conversion efficiency is less than a fourth threshold.

BRIEF DESCRIPTION OF THE FIGURES

[0031] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the disclosure will become apparent from the description, the drawings, and the claims, in which:

[0032] FIG. 1 is an example schematic diagram of an engine-exhaust aftertreatment system coupled to a controller;

[0033] FIG. 2 is an example schematic diagram of the controller used with the engine system of FIG. 1;

[0034] FIG. 3 is an example graph depicting a correlation between mass flow split errors relative to a restriction difference between the legs;

[0035] FIG. 4 is an example graph depicting a correlation between ammonia slips relative to the restriction difference between the legs;

[0036] FIG. 5 an example graph depicting characteristics of the pressure differentials and the volumetric flow rates (e.g., in actual cubic meter per second (ACMS)) relative to certain flow splits;

[0037] FIG. 6 is another example graph depicting characteristics of the pressure differentials and the volumetric flow rates relative to certain flow splits; [0038] FIG. 7 is an overview process flow diagram for an example process for managing mass flow split in a multi -leg aftertreatment system of the engine system of FIG. 1;

[0039] FIG. 8 is an example process flow diagram for performing an example proportionality correction of FIG. 7 in greater detail;

[0040] FIG. 9 illustrates graphs depicting certain example operations associated with a delta pressure-based correction process of FIG. 8 in greater detail;

[0041] FIG. 10 is a block diagram depicting an example matching model of FIG. 8 in greater detail;

[0042] FIG. 11 is an example graph depicting a model-based approach of FIG. 8 for inlet pipe restriction;

[0043] FIG. 12 is an example graph depicting a model-based approach of FIG. 8 for tail pipe restriction;

[0044] FIG. 13 shows example graphs depicting monitored data for a model -based approach of FIG. 8, matching 50-50 flow split data to a respective flow split table;

[0045] FIG. 14 shows example graphs depicting monitored data for a model -based approach of FIG. 8, matching 40-60 flow split data to a respective flow split table;

[0046] FIG. 15 shows example graphs depicting monitored data for a model -based approach of FIG. 8, matching 60-40 flow split data to at least one respective flow split table;

[0047] FIG. 16 shows example graphs depicting monitored data for a model -based approach of FIG. 8, matching a test cell (TC) non-road transient cycle (NRTC) 50-50 flow split data to at least one respective respective flow split table;

[0048] FIG. 17 is an overview process flow diagram of another example process for managing mass flow split in a multi -leg aftertreatment system of the engine system of FIG. 1; [0049] FIG. 18 is a process flow diagram of the example process for managing mass flow split in a multi -leg aftertreatment system associated with FIG. 17 as described in further detail; and

[0050] FIG. 19 illustrates graphs of an example process for NOx monitoring-based correction associated with FIG. 18.

[0051] It will be recognized that some or all of the figures are schematic representations for purposes of illustration. The figures are provided for the purpose of illustrating one or more embodiments with the explicit understanding that they will not be used to limit the scope or the meaning of the claims.

DETAILED DESCRIPTION

[0052] Following below are more detailed descriptions of various concepts related to, and embodiments of, methods, apparatuses, and for determining an efficiency value associated with a catalyst member. The various concepts introduced above and discussed in greater detail below may be implemented in any of a number of ways, as the described concepts are not limited to any particular manner of implementation. Examples of specific embodiments and applications are provided primarily for illustrative purposes.

I. Overview

[0053] Internal combustion engines (e.g., diesel internal combustion engines, etc.) produce exhaust (e.g., sometimes referred to as exhaust gas). Depending on the fuel consumed by an internal combustion engine, the exhaust can contain different byproducts (e.g., NOx, carbon monoxide (CO), unbumed hydrocarbons (HC), etc.). The byproduct of the exhaust can be measured or sensed by one or more sensors of an aftertreatment system, for instance, measuring the density, volume, parts per million (ppm), etc. of the exhaust. The aftertreatment system may be coupled to the engine, such as connected via an exhaust pipe from the engine. For simplicity, the examples herein can provide NOx as the byproducts of the exhaust and the sensor can be a NOx sensor structured to sense NOx emission downstream of the engine (e.g., at any position along the exhaust pipe). Although the described examples include a NOx sensor measuring a NOx byproduct, the described systems can be applied to other sensors.

[0054] The byproducts of the exhaust can be reduced by one or more aftertreatment components of an engine system including an aftertreatment system, such as a DOC member or a SCR catalyst member, among other types of catalysts. The aftertreatment system can include multiple legs. For simplicity, the examples herein provide the aftertreatment system including two legs, however, the aftertreatment system may include more than two legs having respective component s) for reducing the exhaust byproducts. For example, the exhaust can flow or traverse through the aftertreatment system via a first leg and a second leg. The catalyst member (e.g., SCR catalyst member, DOC member, etc.) of each leg can facilitate chemical reactions of the byproducts and reductant to reduce or minimize emissions from a tailpipe of the engine system. For simplicity, the examples herein can provide the SCR catalyst member or the DOC member as the catalyst member of the aftertreatment system. Each leg of the aftertreatment system can be dosed with ammonia (NH3) (e.g., reductant) to reduce the exhaust byproduct. The dosage of reductant can be based on the exhaust gas mass flow rate of the exhaust gas traversing the respective leg.

[0055] However, due to certain piping restrictions or blockages within the aftertreatment system, the mass flow split of exhaust gas may be uneven across the legs (e.g., flow rate of one leg differs from another). The mass flow split refers to the proportion/ratio/percentage of mass flow (or mass flow rate) divided/split between the respective legs of the aftertreatment system. The restriction may be caused by a number of factors including, but not limited to, an asymmetrical tailpipe or other improper installation of the aftertreatment system, soot load, deposit, etc. Further, depending on the location of the restriction, the measured pressure value (e.g., catalyst out pressure), which may be used in some cases for estimating the mass flow rate at the respective legs may not be representative of the actual mass flow rate of the legs. This results in an inaccuracy of mass flow rate estimation which may affect at least the reductant dosage, hydrocarbon (HC) dosage, and/or soot load estimation, etc. Consequently, the inaccurate mass flow rate estimation may lead to at least one of NH3 slip, early or delayed regeneration triggers, and/or poor regeneration control, for example. Therefore, it is desirable to identify any restriction within the aftertreatment system, compute a correction/adjustment factor representing the actual mass flow split, and correct the estimated mass flow rate according to the actual flow split between the legs. It is also desirable to subsequently adjust at least one of reductant dosing, HC dosing, and/or soot load estimation according to the flow split to minimize reductant slip, an untimely trigger of a regeneration event, or poor regeneration control, for example.

[0056] The systems and methods described herein include at least one controller (e.g., computing device or data processing system) including at least one processor coupled to at least one memory. In some cases, the controller can be embedded into a system including the internal combustion engine, the one or more sensors, and the aftertreatment system. In some cases, the controller may be external to the system, such as a server or a cloud-computing device in communication with one or more components of the system. In this case, the controller is configured to receive data from the system, such as sensor data from the sensors monitoring the internal combustion engine or the aftertreatment system.

[0057] In various arrangements, the controller is configured to compute or estimate mass flow rates of exhaust gas traversing through the legs (e.g., a first leg and a second leg) of the aftertreatment system. The controller may estimate the mass flow rate based on pressure data, such as pressure differential (e.g., delta pressure) across a catalyst or outlet pressure of the catalyst. The controller is configured to compute an estimated total mass flow rate based on the estimated mass flow rates. The controller is configured to compare the estimated mass flow rate to an exhaust gas mass flow rate from the engine to determine any flow split imbalance (e.g., uneven mass flow rate) between the legs. The imbalance may be caused by a certain type of restriction within the tailpipe or the aftertreatment system, such as deposit, soot load, asymmetrical tailpipe (either by design or due to misalignment of at least one of the legs), etc. The controller is configured to compute a correction factor to balance the estimated mass flow rates. The correction factor can be based on a multitude of variables, including whether one or more components of the aftertreatment systems have been regenerated, if the aftertreatment system is newly installed, etc. By applying the correction factor to the estimated mass flow rate of each leg, the controller is configured to estimate the corrected mass flow rates of the legs and adjust at least one of reductant dosing, hydrocarbon dosing, or soot load estimation accordingly. Hence, the systems and methods can minimize NOx and reductant slip and control the regeneration trigger for one or more catalysts within an imbalanced aftertreatment system.

[0058] In certain arrangements, the controller is configured to utilize conversion efficiency (e.g., NOx conversion efficiency) to determine an imbalance between the legs and adjust the estimated mass flow rates. For example, the controller is configured to compute a NOx conversion efficiency of the respective legs, for example, using NOx sensors (e.g., monitor the reduction of NOx across the aftertreatment system). Based on the NOx conversion efficiency of the legs, the controller is configured to compute at least one of an average of the NOx conversion efficiencies or a difference between the NOx conversion efficiencies of the legs. Subsequently, if at least one of the average NOx conversion efficiency or the difference is less than a respective threshold, the controller is configured to compute an adjustment factor (e.g., sometimes referred to as a correction factor). The controller is configured to estimate an adjusted mass flow rate by applying the adjustment factor to the estimated flow rates (e.g., based on pressure data). Based on the adjusted mass flow rate across the first leg and the second leg, the controller is configured to adjust at least one of the reductant dosing (e.g., dosing duration, frequency, or timing), hydrocarbon dosing, or soot load estimation. Hence, the systems and methods can further minimize the amount of NOx and/or reductant at the tailpipe and maintain NOx conversion efficiency above a desired efficiency level.

[0059] Through these features, embodiments described herein are capable of alerting a user as to the use of impure fuel and also alerting a user as to the aging of a catalyst member beyond a desirable amount. As a result, embodiments described herein are capable of reducing costs associated with warranty servicing and/or replacements which may be performed when impure fuel is consumed by an engine system.

II. Overview of Multi-Leg Aftertreatment Engine System

[0060] Referring to the figures generally, the various embodiments disclosed herein relate to systems, apparatuses, and methods for managing mass flow split in a multi-leg aftertreatment system. Components in aftertreatment systems to reduce byproducts (e.g., NOx, soot, etc.) of the exhaust include an SCR system that utilizes a two-step process to reduce harmful NOx emissions present in exhaust or a DOC member to filter or oxidize hydrocarbon, carbon monoxide, or unbumed fuel and oil. Referring to the SCR, first, a doser injects a reductant into the exhaust stream. This reductant may be a urea, diesel exhaust fluid (DEF), Adblue®, a urea water solution (UWS), an aqueous urea solution (e.g., AUS32, etc.), or another similar fluid. The reductant may decompose to NH3 post-injection. Then, this mixture is run through an SCR catalyst member that, when at a certain temperature, causes a reaction in the mixture that converts the harmful NOx particles into pure nitrogen and water. In operation, non-decomposed reductant and non-reacted ammonia may be stored within the catalyst member (e.g., SCR catalyst member) to be chemically reacted with the exhaust product (e.g., NOx particles, etc.).

[0061] The amount of reductant injected into the aftertreatment system (e.g., each leg of a multi-leg aftertreatment system) is based on an estimated exhaust gas mass flow rate, at least in part. The mass flow rate may be estimated based on pressure data captured/sensed/measured by at least one pressure sensor in the aftertreatment system. If there is a restriction in the aftertreatment system, however, the estimated mass flow rate may be inaccurate. For instance, certain system configurations may respond to a higher estimated mass flow rate with a higher reductant dosage (e.g., an increase in the rate or duration of reductant dosing) and to a lower estimated mass flow rate with a lower reductant dosage (e.g., a decrease in the rate or duration of reductant dosing). Because of inaccuracy in estimating the mass flow rate, these system configurations may overdose at least one leg leading to ammonia slip or underdose at least one leg leading to NOx slip. Other factors affected by the inaccurate mass flow rate estimation include, but are not limited to, premature or delayed triggering of catalyst regeneration, poor regeneration control (e.g., overdose or underdose of hydrocarbon), or overloading (e.g., soot and deposit load) of at least one of the legs, to list a few. Therefore, the systems and methods discussed herein can perform features and operations to estimate the flow split (e.g., mass flow rates) between the legs of the aftertreatment system, compute a correction/adjustment factor to adjust the estimated flow split, and adjust at least one of a reductant dosing, hydrocarbon dosing, or soot load estimation according to the adjusted flow split, for example. [0062] Referring now to FIG. 1, a schematic diagram of a system 10 with a controller 100 is shown, according to an example embodiment. The system 10 includes an internal combustion engine 20 (referred to as an “engine” hereinafter) coupled to an exhaust aftertreatment system 22 that is in exhaust gas-receiving communication with the engine. As shown, the exhaust aftertreatment system 22 is made up of multiple legs (e.g., first leg 22A and second leg 22B), each leg including respective one or more components of the exhaust aftertreatment system. Although two legs are shown and described for purposes of examples herein, the exhaust aftertreatment system 22 may include more than two legs composed of additional component(s) of the exhaust aftertreatment system 22. The controller 100 is coupled to or in communication with the system 10 along with an operator input/output (I/O) device 120. The system 10 may be embodied in a vehicle. The vehicle may include an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up trucks), cars, boats, tanks, airplanes, locomotives, mining equipment, and any other type of vehicle. The vehicle may include a transmission, a fueling system, one or more additional vehicle subsystems, etc. In this regard, the vehicle may include additional, less, and/or different components/sy stems, such that the principles, methods, systems, apparatuses, processes, and the like of the present disclosure are intended to be applicable with any other vehicle configuration. It should also be understood that the principles of the present disclosure should not be interpreted to be limited to vehicles; rather, the present disclosure is also applicable with stationary pieces of equipment such as a power generator or genset.

[0063] The engine 20 may be a compression-ignition internal combustion engine that utilizes diesel fuel. In various other embodiments, the engine 20 may be structured as any other type of engine (e.g., spark-ignition) that utilizes any type of fuel (e.g., gasoline, natural gas, etc.). In some embodiments, the vehicle may be another type of vehicle, such as a hybrid vehicle containing one or more electric motors, a fuel cell vehicle, and so on. Thus, while the engine 20 is structured as a diesel-powered internal combustion engine herein, other embodiments are contemplated to fall within the scope of the present disclosure.

[0064] Within the internal combustion engine 20, air from the atmosphere is combined with fuel and combusted to power the engine. 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) and to the aftertreatment system 22.

[0065] Each of the legs (e.g., the first leg 22 A and the second leg 22B) of the exhaust aftertreatment system 22 includes a diesel oxidation catalyst (DOC) member 30, a diesel particulate filter (DPF) member 40, a selective catalytic reduction (SCR) system 52 with an SCR catalyst member 50, and an ammonia oxidation (AMOx) catalyst member 60. The first leg 22 A includes DOC member 30 A, DPF member 40 A, SCR system 52 A with a first SCR catalyst member 50A, and AMOx catalyst member 60A. The second leg 22B includes DOC member 30B, DPF member 40B, SCR system 52B with a second SCR catalyst member 50B, and AMOx catalyst member 60B. For simplicity, the components of the respective legs described herein can be labeled generally, for instance, as DOC member 30, DPF member 40, SCR system 52 with a respective SCR catalyst member 50, and AMOx catalyst member 60 associated with the respective first leg 22 A or the second leg 22B.

[0066] The exhaust aftertreatment system 22 further includes an exhaust gas recirculation (EGR) system 70. The SCR systems 52A and 52B of the respective legs further include reductant delivery systems that has diesel exhaust fluid (DEF) sources 54A-B (e.g., DEF source 54 of the legs) that supplies DEF to DEF dosers 56A-B (e.g., referred to generally as doser 56 for the first leg 22A and the second leg 22B) via DEF lines 58A-B, respectively.

[0067] 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, in the first leg 22 A, the exhaust gas flows into the DOC member 30 and exits the DOC member 30 into a first section of exhaust piping 28A. From the first section of exhaust piping 28A, the exhaust gas flows into the DPF member 40 and exits the DPF member 40 into a second section of exhaust piping 28B. From the second section of exhaust piping 28B, the exhaust gas flows into the SCR catalyst member 50 and exits the SCR catalyst member 50 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 (reductant) by the DEF (or reductant) 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 member 60 and exits the AMOx catalyst member 60 into outlet piping 26 before the exhaust gas is expelled from the aftertreatment system 22. Similarly, in the second leg 22B, the exhaust gas flows through pipings 28D-28F passing the various components in the second leg 22B and into the outlet piping 26.

[0068] Based on the foregoing, in the illustrated embodiment, the DOC member 30 (e.g., DOC member 30A or DOC member 30B) is positioned upstream of the DPF member 40 (e.g., DPF member 40A or DPF member 40B) and the SCR catalyst member 50 (e.g., SCR catalyst member 50A or SCR catalyst member 50B), and the SCR catalyst member 50 (e.g., SCR catalyst member 50A or SCR catalyst member 50B) is positioned downstream of the DPF member 40 (e.g., DPF member 40 A or DPF member 40B) and upstream of the AMOx catalyst member 60 (e.g., AMOx catalyst member 60A or AMOx catalyst member 60B). However, in alternative embodiments, other arrangements of the components of the exhaust aftertreatment system 22 are also possible. Further, and for simplicity, the components of a leg in the exhaust aftertreatment system 22 may be similar to another leg. Alternatively, one or more components or the arrangement of the components in the first leg 22A may be different from those in the second leg 22B, and so forth.

[0069] The DOC member 30 may be structured to have any number of different types of flow-through designs. The DOC member 30 may be structured to oxidize at least some particulate matter in the exhaust (e.g., the soluble organic fraction of soot) and reduce unbumed hydrocarbons and CO in the exhaust to less environmentally harmful compounds. For example, the DOC member 30 may be structured to reduce the hydrocarbon and CO concentrations in the exhaust to meet the requisite emissions standards for those components of the exhaust. An indirect consequence of the oxidation capabilities of the DOC member 30 is the ability of the DOC member 30 to oxidize NO into NO2. In this manner, the level of NO2 exiting the DOC member 30 is equal to the NO2 in the exhaust generated by the engine 20 in addition to the NO2 converted from NO by the DOC member 30.

[0070] In addition to treating the hydrocarbon and CO concentrations in the exhaust, the DOC member 30 may also be used in the controlled regeneration of the DPF member 40, SCR catalyst member 50, and AMOx catalyst member 60. This can be accomplished through the injection, or dosing, of unburned HC into the exhaust upstream of the DOC member 30. Upon contact with the DOC member 30, the unburned HC undergoes an exothermic oxidation reaction which leads to an increase in the temperature of the exhaust exiting the DOC member 30 and subsequently entering the DPF member 40, SCR catalyst member 50, and/or the AMOx catalyst member 60. The amount of unburned HC added to the exhaust is selected to achieve the desired temperature increase or target controlled regeneration temperature.

[0071] The DPF member 40 may be any of various flow-through designs, and is structured to reduce particulate matter concentrations (e.g., soot and ash) in the exhaust to meet requisite emission standards. The DPF member 40 captures particulate matter and other constituents, and thus can be periodically regenerated to burn off the captured constituents. Additionally, the DPF member 40 may be structured to oxidize NO to form NO2 independent of the DOC member 30.

[0072] As discussed above, the SCR system 52 includes a reductant delivery system. The reductant delivery system includes a reductant (e.g., DEF) source 54, pump (not shown), and a doser 56 (e.g., sometimes referred to as delivery mechanism 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), diesel oil, etc. The reductant source 54 is in reductant supplying communication with the pump, which is structured to pump reductant from the reductant source 54 to the delivery mechanism 56 via a reductant delivery line 58. The delivery mechanism 56 is positioned upstream of the SCR catalyst member 50. The delivery mechanism 56 is selectively controllable to inject reductant directly into the exhaust stream prior to entering the SCR catalyst member 50. As described herein, the controller 100 is structured to control a timing and amount of the reductant delivered to the exhaust, such as based on estimated or computed mass flow rate across each leg of the exhaust aftertreatment system 22. The reductant may decompose to produce ammonia. As briefly described above, the ammonia reacts with NOx in the presence of the SCR catalyst member 50 to reduce the NOx to less harmful emissions, such as N2 and H2O. The NOx in the exhaust stream includes NO2 and NO. Both NO2 and NO are reduced to N2 and H2O through various chemical reactions driven by the catalytic elements of the SCR catalyst member in the presence of NH3.

[0073] In some embodiments, the SCR catalyst member 50 is a vanadium-based catalyst member, and in other embodiments, the SCR catalyst member is a zeolite-based catalyst member, such as a copper-zeolite (Cu-Ze) or an iron-zeolite (Fe-Zu) catalyst member. In one representative embodiment, the reductant is aqueous urea and the SCR catalyst member 50 is a zeolite-based catalyst member. In other embodiments, the reductant includes a first reductant and a second reductant, wherein the first reductant is urea and the second reductant is ammonia.

[0074] The AMOx catalyst member 60 may be any of various flow-through catalyst members structured to react with ammonia to produce mainly nitrogen. As briefly described above, the AMOx catalyst member 60 is structured to remove ammonia that has slipped through or exited the SCR catalyst member 50 without reacting with NOx in the exhaust. In certain instances, the aftertreatment system 22 can be operable with or without an AMOx catalyst member. Further, although the AMOx catalyst member 60 is shown as a separate unit from the SCR system 52 in FIG. 1, in some embodiments, the AMOx catalyst member may be integrated with the SCR catalyst member (e.g., the AMOx catalyst member and the SCR catalyst member can be located within the same housing). As referred to herein, the SCR catalyst member 50 and AMOx catalyst member 60 form the SCR and AMOx system.

[0075] The system 10 (e.g., the aftertreatment system 22) includes various sensors. For example, the aftertreatment system 22 includes NOx sensors 12. The aftertreatment system 22 includes temperature sensors 14. The aftertreatment system 22 includes pressure sensors 16. The sensors can be strategically disposed throughout the aftertreatment system 22, such as upstream, at, or downstream from one or more catalysts (e.g., DOC member 30, DPF member 40, SCR catalyst member 50, and/or AMOx catalyst member 60). The sensors can be in communication with the controller 100 and configured to monitor operating conditions of the system 10. It should be understood that one or more NOx, pressure, temperature, and a variety of other sensors (oxygen sensors, exhaust constituent sensors, NH3 sensors) may also be included in the system and disposed in a variety of locations. [0076] As shown, one or more pressure sensors 16 may be positioned upstream and downstream of the catalyst member(s). In this configuration, the pressure sensor 16 measures at least one of the outlet pressure, the inlet pressure, or the pressure at the catalyst member (e.g., pressure sensor 16 inside the catalyst member (not shown)). For simplicity, and for purposes of examples herein, the DPF member 40 can be provided as the catalyst member of which the pressure data is monitored for estimating the mass flow rate or the flow rate of exhaust gas. However, the pressure sensors 16 may be positioned upstream, downstream, or at other catalyst members, such as the SCR catalyst member 50, DOC member 30, or AMOx catalyst member 60, for example. The pressure data is used by the controller 100 for estimating the mass flow rate.

[0077] Further, more than one NOx sensor may be positioned upstream and downstream of the catalyst member(s). In some configurations, one NOx sensor 12 measures the engine out NOx while another NOx sensor 12 measures the SCR catalyst member 50 inlet NOx amount. This is due to DOC member 30/DPF member 40 potentially oxidizing some portion of the engine out NOx whereby the engine out NOx amount would not be equal to the SCR catalyst member 50 inlet NOx amount. Accordingly, this configuration accounts for this potential discrepancy. The NOx amount leaving the SCR catalyst member 50 may be measured by a NOx sensor 12 downstream from the SCR catalyst member 50 and/or NOx sensor 12 downstream of the AMOx catalyst member 60. The NOx sensor 12 (in some embodiments, NOx sensor 12) is positioned downstream of the SCR catalyst member 50 and structured to detect the concentration of NOx in the exhaust downstream of the SCR catalyst member (e.g., exiting the SCR catalyst member). The measurements (e.g., measured NOx data) from the NOx sensor 12 is used by the controller 100 to determine the NOx conversion efficiency across the respective leg of the aftertreatment system 22. The NOx conversion efficiency corresponds to the amount of NOx reduced across the one or more components of the aftertreatment system 22. Although a NOx sensor 12 is shown at the outlet of the engine 20, respective NOx sensors 12 can be provided upstream of the respective DOC member 30 or DPF member 40 of each leg.

[0078] The temperature sensors 14 are associated with one or more catalyst members. The temperature sensors 14 are strategically positioned to detect the temperature of exhaust flowing into the DOC member 30 (e.g., the temperature of the exhaust conduit upstream from the catalyst member), out of the DOC member 30 (e.g., the temperature of the exhaust conduit downstream from the catalyst member) and into another catalyst member (e.g., from the DOC member 30 to the DPF member 40), and out of the DPF member 40 before being dosed with DEF by the doser 56. In some embodiments, at least one temperature sensor 14 may be configured as part of the catalyst member itself, thereby directly measuring a bed temperature of the catalyst member.

[0079] The EGR system 70 is structured to recirculate exhaust back to an intake manifold of the engine 20 to be used for combustion. The EGR system 70 includes an EGR cooler 74 and an EGR valve 76. The EGR cooler 74 may be, for example, air-to-air and/or liquid (e.g., coolant)-to-air (e.g., exhaust) heat exchangers, in some applications. The EGR cooler 74 is structured to remove heat from the exhaust prior to the exhaust being re-introduced into the intake manifold. Heat is removed from the exhaust prior to reintroduction to, among other reasons, prevent high intake temperatures that could promote pre-ignition (e.g., engine knock).

[0080] Although the exhaust aftertreatment system 22 shown includes the DOC member 30, the DPF member 40, the SCR catalyst member 50, and the AMOx catalyst member 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 DOC member 30, DPF member 40, SCR catalyst member 50, and AMOx catalyst member 60 positioned in any of various positions relative to each other along the exhaust flow path.

[0081] FIG. 1 is also shown to include an operator input/output (VO) device 120. The operator I/O device 120 is communicably coupled to the controller 100, such that information may be exchanged between the controller 100 and the I/O device 120. The information exchanged between the controller 100 and the VO device 120 may relate to one or more components of FIG. 1 or any of the determinations of the controller 100 disclosed herein. The operator I/O device 120 enables an operator (e.g., occupant, etc.) of the vehicle to communicate with the controller 100 and other components of the vehicle, such as those illustrated in FIG. 1. For example, the operator I/O device 120 may include an interactive display, a touchscreen device, one or more buttons and switches, voice command receivers, etc. In some cases, the I/O device 120 may be a part of a vehicle including the engine 20 and the aftertreatment system 22. In some other cases, the I/O device 120 may be a remote device accessible by the operator, such as via a client device. In some aspects, the I/O device 120 may be a server receiving data from the controller 100 of the vehicle.

[0082] The controller 100 is structured to monitor the operations, conditions, or events within the system 10 (e.g., components of the aftertreatment system 22). The controller 100 is structured to control, at least partly, operation of the system 10 and associated sub-systems, such as the internal combustion engine 20 and the exhaust aftertreatment system 22. Communication between and among the components may be via 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. In comparison, a wireless connection may include the Internet, Wi-Fi, cellular, radio, Bluetooth, 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. Because the controller 100 is communicably coupled to the systems and components of FIG. 1, the controller 100 is configured to receive data from one or more of the components shown in FIG. 1. For example, the data may include NOx data (e.g., an incoming NOx amount from NOx sensor 12 and an outgoing NOx amount from NOx sensor 12), dosing data (e.g., timing and amount of dosing delivered from doser 56), and vehicle operating data (e.g., engine speed, vehicle speed, engine temperature, flow rate, etc.) received via one or more sensors. As another example, the data may include an input from operator input/output device 120. As described more fully herein, using this data, the controller 100 monitors the multi-leg aftertreatment system 22 to determine if there is a restriction causing an imbalance in the flow split across individual legs and to diagnose the imbalance, such as to minimize reductant slip and NOx slip and optimize regeneration control or trigger. The structure, function, or configuration of the controller 100 are further described in regard to FIG. 2.

[0083] FIG. 2 shows an example structure for the controller 100 includes a processing circuit 101 including a processor 102, a memory 103, and various circuits including at least an engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111. The processor 102 may be implemented as 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. The memory 103 (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 memory 103 may be communicably connected to the processor 102 and one or more circuits. In various embodiments, the memory 103 includes the engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111. The memory 103 is configured to provide computer code or instructions to the processor 102 for executing the processes described in regard to the controller 100 herein. Moreover, the memory 103 may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory 103 may 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.

[0084] The controller 100 includes a communications interface 104. The communications interface 104 may include any combination of wired and/or wireless interfaces (e.g., jacks, antennas, transmitters, receivers, transceivers, wire terminals) for conducting data communications with various systems, devices, or networks structured to enable in-vehicle communications (e.g., between and among the components of the vehicle) and out-of-vehicle communications (e.g., directly with remote computing system). In this regard, in some embodiments, the communications interface 104 includes a network interface. The network interface is used to establish connections with other computing devices by way of a network. The network interface includes program logic that facilitates connection of the controller 100 to the network. The network interface includes any combination of a wireless network transceiver (e.g., a cellular modem, a Bluetooth transceiver, a Wi-Fi transceiver) and/or a wired network transceiver (e.g., an Ethernet transceiver). In some arrangements, the network interface includes the hardware and machine-readable media sufficient to support communication over multiple channels of data communication. Further, in some arrangements, the network interface includes cryptography capabilities to establish a secure or relatively secure communication session in which data communicated over the session is encrypted. For example and regarding out-of- vehicle/system communications, the communications interface 104 may include an Ethernet card and port for sending and receiving data via an Ethernet-based communications network and/or a Wi-Fi transceiver for communicating via a wireless communications network. The communications interface 104 may be structured to communicate via local area networks and/or wide area networks (e.g., the Internet) and may use a variety of communications protocols (e.g., IP, LON, Bluetooth, ZigBee, and radio, cellular, near field communication). Furthermore, the communications interface 104 may work together or in tandem with a telematics unit, if included, in order to communicate with other vehicles in the fleet and/or the remote computing system.

[0085] The controller 100 is structured to receive inputs (e.g., signals, information, data, etc.) from the system 10 components/sy stems and/or the operator I/O device 120. Thus, the controller 100 is structured to control, at least partly, the system 10 components/sy stems and associated engine 20. As the components of FIG. 2 can be embodied in a vehicle, the controller 100 may be configured as one or more electronic control units (ECU). The controller 100 may be separate from or included with at least one of a transmission control unit, an exhaust aftertreatment control unit, a powertrain control module, an engine control module, etc. In some cases, the controller 100 may be a device remote from the vehicle, such as a remote controller configured to control or communicate with one or more components of the system 10.

[0086] In one configuration, one or more of the an engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, or adjustment circuit 111 can be embodied as a machine or computer-readable media that stores instructions that are executable by a processor, such as the processor 102, and stored in a memory device, such as the memory 103. As described herein and amongst other uses, the machine-readable media facilitates performance of certain operations to 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). 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.).

[0087] In another configuration, the one or more circuits are embodied as hardware units, such as electronic control units. For example, the one or more circuits may 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 one or more circuits may 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.” The one or more circuits may 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). The one or more circuits may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. The one or more circuits may include one or more memory devices for storing instructions that are executable by the processor(s) of the individual circuits (e.g., engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111). The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory 103 and processor 102. In some hardware unit configurations, the one or more circuits may be geographically dispersed throughout separate locations in, for example, a vehicle. Alternatively and as shown, the one or more circuits may be embodied in or within a single unit/housing, which is shown as the controller 100. [0088] In the example shown, the controller 100 includes the processing circuit 101 having the an engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111. The processing circuit 101 may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to the one or more circuits. The depicted configuration represents an engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111 as instructions in machine or computer-readable media. In some embodiments, the instructions may be stored by the memory device. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments where the engine circuit 105, ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111, or at least one of the one or more circuits, is configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure.

[0089] In the example shown, the controller 100 includes at least the engine circuit 105 structured to control the engine 20, an ammonia circuit 106 in communication with sensors associated with the SCR catalyst member 50 and/or the AMOx catalyst member 60, a NOx circuit 107 in communication with the NOx sensors 12, a flow rate circuit 108 in communication with the pressure sensors 16 to estimate the mass flow rate across the aftertreatment system 22, a correction circuit 109 configured to compute and apply a correction factor to the estimated mass flow rate, a modeling circuit 110 in communication with other circuits and configured to manage models regarding predefined flow and their respective correction factors to be used by the correction circuit 109, and an adjustment circuit 111 in communication with the other circuits and configured to adjust at least one of the reductant dosing control, hydrocarbon control, or soot load estimation based on the correction factor applied to the estimated mass flow rate, for example.

[0090] The engine circuit 105 is structured to receive information from a user or an operator (e.g., via the operator input/output device 120) and to provide instructions to or otherwise control the engine 20. For instance, the engine circuit 105 can control the operations or components of the engine including at least the intake valve for controlling intake air or gas, the exhaust valve to release the exhaust through the pipe (e.g., piping 24, 28A-F, 26, etc.), or other components of the engine 20. Thus, the engine circuit 105 may control a torque and/or speed of the engine 20. The engine circuit 105 is structured to receive information associated with the engine 20, such as a fueling amount, a temperature, etc. The engine circuit 105 is structured to communicate the engine information to one or more other circuits (e.g., ammonia circuit 106, NOx circuit 107, flow rate circuit 108, correction circuit 109, modeling circuit 110, and adjustment circuit 111, etc.) of the controller 100 and to components of the memory 103.

[0091] The ammonia circuit 106 is configured to communicate with the doser 56, the temperature sensors 14, and the NOx sensors 12 to determine the amount of ammonia (or reductant) stored in the SCR catalyst member 50, for example. In some cases, the ammonia circuit 106 is configured to control the doser 56 to supply or introduce reductant into the pipeline. In this case, the ammonia circuit 106 is configured to determine the reductant dosing rate including the duration, frequency, and timing. Hence, the ammonia circuit 106 can determine the amount of reductant stored in the SCR catalyst member 50 using at least one of the dosing rate of reductant and data from one or more other circuits, such as the amount of NOx at the inlet of the SCR catalyst member 50 and the amount of NOx at the outlet of the SCR catalyst member 50 (e.g., amount of NOx converted via the catalyst member), and/or the mass flow rate in the respective leg.

[0092] The NOx circuit 107 is coupled to and communicates with the NOx sensors 12 and provides information regarding NOx levels to other circuits of the controller 100 and to components of the memory 103. The one or more NOx sensor(s) may be virtual NOx sensor(s) or physical NOx sensor(s). The NOx circuit 107 may process raw data received from the NOx sensors 12 in addition to other sensor data to provide information indicative of a NOx level to other circuits of the controller 100 and to components of the memory 103.

[0093] The flow rate circuit 108 is coupled to and communicates with the pressure sensors 16 and provides information regarding the magnitude of the pressure or other pressure data to other circuits of the controller 100 and to components of the memory 103. The one or more pressure sensor(s) may be virtual pressure sensor(s) or physical pressure sensor(s). The flow rate circuit 108 may process raw data received from the pressure sensors 16 in addition to other sensor data to provide information indicative of a pressure level to other circuits of the controller 100 and to components of the memory 103. Using the pressure data, the flow rate circuit 108 is configured to estimate a mass flow rate at the locations corresponding to the pressure sensors 16, for example.

[0094] The correction circuit 109 is configured to communicate with other circuits, including receiving data from at least one of the NOx circuit 107 (e.g., NOx measurements) or the flow rate circuit 108 (e.g., pressure data or mass flow rate data). The correction circuit 109 is configured to compute a correction factor (e.g., sometimes referred to as an adjustment factor) for adjusting the estimated mass flow rate estimated based on the pressure data. For example, the correction circuit 109 is configured to receive estimates of the mass flow rate across individual legs of the aftertreatment system 22. The correction circuit 109 is configured to identify an imbalance flow split due to a restriction when the total estimated mass flow rate across the legs is not within the range of the engine exhaust mass flow rate. If there is an imbalance or inaccuracy in the estimated mass flow rate, the correction circuit 109 is configured to use the techniques and operations described herein to compute the correction factor for calibrating or diagnosing the estimated mass flow rates. In various embodiments, the correction circuit 109 is configured to account for SCR deposit (e.g., whether to perform regeneration), newly installed system, and balanced flow split due to accumulated soot load.

[0095] The modeling circuit 110 is configured to manage models representative of predefined flow splits of the aftertreatment system 22. The models can be stored in the memory 103 or a remote database. The modeling circuit 110 is configured to retrieve the models from the memory 103 or the remote database. The modeling circuit 110 is configured to modify or adjust the model given any updated information from the operator I/O device 120. The flow splits associated with each model may be predefined, such as 50-50 (e.g., 50% of the engine exhaust mass flow rate across the first leg 22A and 50% of the exhaust mass flow rate across the second leg 22B), 65-35 (e.g., 65% across the first leg 22A and 35% across the second leg 22B), 55-45 (e.g., 55% across the first leg 22A and 45% across the second leg 22B), etc. Each model corresponding to a predefined flow split can be associated with a respective correction factor (e.g., predetermined for the respective flow split and pressure data). The correction factor can be a multiplier, percentage, or amount of mass flow rate for increasing or decreasing the estimated mass flow rate for at least one of the legs based on the flow split estimation. The modeling circuit 110 is configured to compare the pressure data (e.g., catalyst out pressure or pressure differential across the catalyst member) representative of the estimated flow split to the various models over time. The modeling circuit 110 is configured to select at least one of the models having a predefined flow split similar to the estimated flow split. The modeling circuit 110 is configured to communicate or provide a correction factor of the select model to the correction circuit 109 for adjusting the estimated mass flow rates.

[0096] The adjustment circuit I l l is configured to communicate with other circuits including the ammonia circuit 106, the NOx circuit 107, the flow rate circuit 108, the correction circuit 109, etc. The adjustment circuit 111 communicates with the other circuits to obtain information including at least one of the NOx conversion efficiency, mass flow rate estimations, amount of stored reductant (e.g., ammonia), NOx produced by the engine, the amount of NOx in each leg, the correction factor, etc. In some cases, the adjustment circuit 111 communicates directly to the components of the systems including the sensors, doser 56, or others. Using the information obtained from the system, the adjustment circuit I l l is configured to adjust at least one of the estimated mass flow rate by applying the correction factor, the dosing rate of reductant, the hydrocarbon injection (e.g., regeneration) timing, or soot load estimation. The adjustments to the dosing rate, regeneration timing, or soot load estimation is based at least in part on the adjusted estimated mass flow rate, which represents the amount of exhaust byproducts that traverses the legs of the aftertreatment system 22. As described herein, the one or more circuits of the controller 100 are configured to detect and diagnose an imbalance within the aftertreatment system 22.

[0097] Referring to FIG. 3, depicted is an example graph 300 illustrating a correlation between mass flow split errors relative to the restriction difference between the legs. The x-axis can represent the leg-to-leg restriction difference (e.g., the proportion of restriction in one leg compared to another leg or tailpipe pressure drop delta at a certain rated flow) and the y-axis can represent the level of error in the mass flow split ratio. For example, in certain systems, there may be a restriction at a tailpipe outlet of the system. In such systems, an increase in the restriction difference between the legs (e.g., one leg has more restriction than the other) can lead to more error in the flow split ratio (e.g., error in the estimation of mass flow rate between the legs). As shown, the increase in the error (e.g., delta value increase from zero) can be proportional to the increase in the restriction difference (e.g., an increase in leg-to-leg tailpipe pressure drop delta). The increase in the error represents a degradation in the accuracy of the determined mass flow split ratio. In this case, as the value in the y-axis of graph 300 lowers (e.g., accuracy decreases or error increases), more NH3 slips from the tailpipe, as shown in connection with FIG. 4.

[0098] Referring to FIG. 4, depicted is an example graph 400 illustrating a correlation between ammonia slip relative to restriction difference between the legs. The x-axis can represent the leg-to-leg restriction difference (e.g., tailpipe pressure drop delta at a certain rated flow) and the y-axis can represent the difference in the amount of ammonia slip between the legs (e.g., leg-to-leg delta). The higher value in the y-axis represents more ammonia slip occurring from at least one of the legs. Further in such systems described in FIG. 3, because of an increase in the restriction difference, the systems may experience an increase in reductant slippage. For instance, the restriction difference may cause the certain systems to overestimate the mass flow rate traversing across at least one of the legs. Hence, the systems may increase the dosing rate of reductant when the estimated mass flow rate does not represent the actual mass flow rate, thereby causing an overdosage of reductant. In some other instances, the restriction difference may cause the systems to underestimate the mass flow rate across at least one of the legs. In such cases, the systems may underdose the leg, causing an increase in NOx slip. Hence, the systems and methods configure the controller 100 to detect the imbalance caused by restrictions in at least one of the legs and diagnose the imbalance to at least minimize the reductant slip or NOx slip. As shown, an increase in ammonia slip is proportional to an increase to the increase in the restriction difference (e.g., an increase in leg-to-leg tailpipe pressure drop delta).

[0099] Referring to FIG. 5, depicted is an example graph 500 of collected data including the pressure signatures or measurements when a restriction is upstream of the catalyst outlet of the second leg 22B (e.g., upstream from the pressure sensor 16 at an outlet of the catalyst member). The y-axis represents the pressure readings (e.g., delta pressure reading across a certain catalyst member) relative to the x-axis representing the total mass flow rate from the engine 20 (e.g., referred to as an exhaust mass flow rate). The mass flow rate is measured in actual cubic meters per second (ACMS). In this case, the restriction may be caused by an inlet piping to an aftertreatment system, such as misalignment or obstruction, or inside the catalyst member (e.g., soot load differences between the two legs). Because of the restriction, this system may experience an imbalance in the mass flow rate, as shown in FIG. 5. For example, the data points (e.g., baseline data points) labeled in the legend as 0% represent the pressure measurements of a balanced system. The balance system refers to a system with a 50-50 flow split across the legs of the aftertreatment system 22. With a restriction upstream from the pressure sensor 16, the data points regarding the leg having a higher mass flow rate (e.g., labeled as 60%) is shown to be above the balanced data points, representing relatively higher pressure readings. Further, the data points regarding the leg having a lower mass flow rate (e.g., labeled as “low flow leg”) is shown to be below the balanced data points, representing relatively lower pressure readings. In this case, with 60% inlet valve position, the flow split is 55-45 (or 55% and 45%, respectively), where 55% (e.g., labeled in the legend) of the exhaust mass flow rate traverses the high flow leg, and 45% of the exhaust mass flow rate traverses the low flow leg. Hence, such characteristics of the high flow leg and the low flow leg represent that the restriction is upstream from the pressure sensor 16. When there is restriction upstream of the pressure sensor location (e.g., measuring the pressure at the outlet of the DPF member 40), the sum of the individual leg mass flow rates is equal to or around the same as the engine exhaust gas mass flow rate.

[0100] The valve position can be adjusted to mimic different tailpipe or inlet pipe dissymmetries in a test cell (e.g., adjust, manage, or control the symmetries between the legs). The valve position can be used to avoid the need to fabricate different tailpipes for each leg or find the space of a standard test cell size to fit the different tailpipes, for example. In the examples discussed above, the 60% inlet valve position corresponds to maintaining a second leg (leg 2) inlet valve (valve 2) at 60% closed position, while all other valves are left open (0% closed position), resulting in 55% flow in a first leg (leg 1) and 45% flow in the leg 2. In some cases, the 90% outlet valve position corresponds to maintaining the leg 2 outlet valve (valve 4) at 90% closed position, while all other valves are open (0% closed position), resulting in 60% flow via the leg 1 and 40% flow via leg 2. The 60% inlet valve position may correspond to a certain length of additional piping or pipe bends on the inlet side of leg 2 compared to leg 1, for example. Similarly, the 90% on the outlet side may correspond to a certain additional length of piping or pipe bends on leg 2 on the outlet side compared to the leg 1 outlet, hence causing the restriction or differences in the flow between the first and second legs.

[0101] Referring to FIG. 6, depicted is an example graph 600 of collected data including pressure signatures or measurements when a restriction is downstream of the catalyst outlet of the second leg 22B (e.g., downstream from the pressure sensor 16 at the outlet of the catalyst member). As shown, similar to FIG. 5, the baseline data points are shown in the graph (e.g., labeled in the legend as 0%) indicating pressure signatures for a balanced system. The x- axis and the y-axis of graph 600 are similar to the x-axis and the y-axis of graph 500. In some cases, the restriction is downstream from the pressure sensor 16 of the second leg 22B. As shown, the pressure measurements for the first leg 22A and the second leg 22B (e.g., having 90% outlet valve position (labeled in the legend) representing 60-40 flow split) are above the baseline data points, indicating that the restriction is downstream from the pressure sensor 16. Consequently, for restrictions downstream from the pressure sensor 16, the pressure signatures collected by the pressure sensor 16 are higher than the baseline data for both the high flow leg and the low flow leg (e.g., reversed pressure signature for the low leg as shown in portion 602).

[0102] In the case of a restriction upstream of the pressure sensor 16 used to estimate the mass flow rate, the system may not require a correction/adjustment factor to correct/adjust the estimated mass flow rate. However, in the case of a restriction downstream from the pressure sensor 16, the system is configured to identify variables that may contribute to the downstream restriction to resolve or diagnose the imbalance mass flow rate (e.g., overestimated and/or underestimated mass flow rates).

[0103] Referring to FIG. 7, depicted is an example overview process flow diagram for a mass flow split managing process 700 in a multi-leg aftertreatment system using pressure information. The processes, operations, or steps of FIG. 7 can be performed, operated, or executed by the components (e.g., controller 100, I/O device 120, aftertreatment system 22, sensors, etc.) of the system 10, data processing system, cloud computing environment, or any other computing devices described herein in conjunction with FIGS. 1-6. For example, additional or alternative operations of the process 700 can be performed by one or more circuits of the controller 100. Additionally or alternatively, some operations of the process 700 can be performed by a remote device, such as a remote data processing system. Some operations of the process 700 may involve the controller 100 receiving data from components of the aftertreatment system 22, such as one or more sensors, and forwarding the data to the remote device for processing, or vice versa.

[0104] At step 702, the controller 100 (e.g., flow rate circuit 108) is configured to estimate a first mass flow rate of exhaust gas in the first leg 22A. The first mass flow rate of exhaust gas can be estimated based on pressure data from pressure sensors 16 of the first leg 22 A, such as catalyst out pressure or pressure differential across the catalyst member (e.g., a first DPF member).

[0105] At step 704, the controller 100 (e.g., flow rate circuit 108) is configured to estimate a second mass flow rate of the exhaust gas in the second leg 22B. The second mass flow rate of exhaust gas can be estimated based on pressure data from pressure sensors 16 of the second leg 22B, such as catalyst out pressure or pressure differential across the catalyst member (e.g., a second DPF member).

[0106] At step 706, the controller 100 (e.g., flow rate circuit 108) is configured to compute an estimated total mass flow rate based on the estimated first mass flow rate and the estimated second mass flow rate. The controller 100 can compute the estimated total mass flow rate by summing the estimated first mass flow rate and the estimated second mass flow rate. In various embodiments, the controller 100 is configured to compute the estimated total mass flow rate using other means, operations, or techniques.

[0107] At step 708, the controller 100 (e.g., flow rate circuit 108) determines that the estimated total mass flow rate is greater than an engine exhaust mass flow rate. The engine exhaust mass flow rate corresponds to the total mass flow rate at the outlet of the engine 20. In response to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate, the controller 100 (e.g., correction circuit 109) is configured to compute a correction factor for balancing the estimated first mass flow rate and the estimated second mass flow rate. Balancing the estimated first mass flow rate and the estimated second mass flow rate can refer to correcting at least one of the mass flow rates such that the total of the estimated mass flow rates is at or around (e.g., within 5%, 3%, etc., deviation of) the engine exhaust mass flow rate or within a predetermined threshold/range of the engine exhaust mass flow rate. Having the estimated total mass flow rates at or around the engine exhaust indicates that the estimated mass flow rate of each leg is accurate.

[0108] At step 710, the controller 100 (e.g., flow rate circuit 108 or correction circuit 109) is configured to estimate a corrected first mass flow rate of the exhaust gas in the first leg 22A and a corrected second mass flow rate of the exhaust gas in the second leg 22B using the correction factor. The controller 100 is configured to apply the correction factor to the estimated mass flow rate of each leg to increase or decrease the estimated mass flow rate. In some cases, the correction factor indicates a proportion of the engine exhaust mass flow rate received by each of the legs. In this case, the controller 100 is configured to apply the correction factor to the engine exhaust mass flow rate to estimate the corrected first mass flow rate and the corrected second mass flow rate based on the proportion.

[0109] At step 712, the controller 100 (e.g., adjustment circuit 111) is configured to adjust at least one of a reductant dosing, hydrocarbon dosing, or soot load estimation based on the corrected first mass flow rate and the corrected second mass flow rate. An increase from the estimated mass flow rate to the corrected mass flow rate may result in at least one of an increase in the reductant dosing, advancing the timing or frequency of the hydrocarbon dosing, or increasing the soot load estimation because of the increase in the exhaust byproducts in the leg. A decrease from the estimated mass flow rate to the corrected mass flow rate may result in at least one of a decrease in the reductant dosing, retarding the timing or frequency of the hydrocarbon dosing, or decreasing the soot load estimation because of the decrease in the exhaust byproducts in the leg. In various arrangements, the operations, techniques, or features of process 700 can be described in further detail in conjunction with FIG. 8. [0110] Referring to FIG. 8, depicted is an example process flow diagram for performing an example proportionality correction process 800 of FIG. 7 in a multi-leg aftertreatment system using pressure information. The processes, operations, or steps of FIG. 8 can be performed, operated, or executed by the components (e.g., controller 100, I/O device 120, aftertreatment system 22, sensors, etc.) of the system 10, data processing system, cloud computing environment, or any other computing devices described herein in conjunction with FIGS. 1-7. For example, additional or alternative operations of the process 800 can be performed by one or more circuits of the controller 100. Additionally or alternatively, some operations of the process 800 can be performed by a remote device, such as a remote data processing system. Some operations of the process 800 may involve the controller 100 receiving data from components of the aftertreatment system 22, such as one or more sensors, and forwarding the data to the remote device for processing, or vice versa.

[0111] The process 800 starts at step 802. For example, at step 802, the controller 100 may receive a command or an indication to initiate an operation for monitoring and diagnosing imbalance flow split within the system 10. The controller 100 receives the command from the I/O device 120 or other remove devices via the communications interface 104. In some cases, the controller 100 initiates the process 800 in response to receiving an indication (e.g., from another processing device) that there is a restriction within the system, such as a restriction downstream from the pressure sensors 16 used to estimate the mass flow rate.

[0112] At step 804, the controller 100 (e.g., flow rate circuit 108) estimates or computes the mass flow rate of each leg (e.g., first leg 22A and/or second leg 22B) of the aftertreatment system 22. Each leg includes respective one or more components of the aftertreatment system 22. For each leg, the flow rate circuit 108 estimates the mass flow rate based on pressure information associated with a catalyst member (e.g., DPF member 40 or other catalyst members). The pressure information includes at least one of catalyst out pressure (e.g., DPF out pressure) or delta pressure (e.g., pressure differential/difference across the DPF member 40 or the difference between pressure at the inlet and pressure at the outlet of the DPF member 40). The flow rate circuit 108 may use the following equation/formula to estimate the mass flow rate based on pressure data:

A = open frontal area of SCR catalyst member 50 or subsequent catalyst member from the DPF member 40. m = mass flow rate k = flow coefficient p = density

Δ = delta

P = pressure

[0113] In some cases, the flow rate circuit 108 is configured to use the following simplified model for computing the mass flow rate: k = flow coefficient, which can be implemented as a lookup table

DPF = DPF member 40 (e.g., other catalyst members may be used)

OutP = pressure at outlet of the catalyst member

AmbP = ambient pressure or pressure surrounding the catalyst member

[0114] The flow rate circuit 108 computes the density (rho) as follows:

P _bed = bed pressure of the catalyst member R = ideal gas constant

T _bed ⁼ bed temperature of the catalyst member

[0115] To iteratively converge this m to its true value, the flow rate circuit 108 uses a conversion technique (e.g., Newton-Raphson method) to compute the estimated mass flow rate for a respective leg: m _est = estimated mass flow rate

[0116] An acceptable or desired range of flow accuracy (e.g., differences between mass flow rate from one leg to another) is +/- 2% or +/- 3% above or below the minimum mass flow rate (e.g., total engine flow rate of 24 kg/min, 18 kg/min, etc.). In response to the degradation in the accuracy for estimating the flow split between the legs, such as due to noise or restriction downstream from the one or more sensors 16, the flow rate circuit 108 is configured to utilize the equations for estimating the correction factor.

[0117] The flow rate circuit 108 uses the estimated mass flow to identify the mass flow in one leg relative to the other, thereby normalizing the modeling errors of the mass flow rate computation. Based on the equations above, the flow rate circuit 108 can estimate the mass flow rate in each leg (e.g., a first mass flow rate of exhaust gas in the first leg 22 A and a second mass flow rate of exhaust gas in the second leg 22B) based on at least one of catalyst out pressure or pressure differential across the catalyst member. In some embodiments, the flow rate circuit 108 is configured to use other equations to estimate the mass flow rate in the system. [0118] The flow rate circuit 108 computes an (e.g., estimated) total mass flow rate based on the estimated mass flow rates of the legs. For simplicity, the estimated total mass flow rate corresponds to the sum of the estimated mass flow rates at a certain time instance or over a time window. In some cases, the flow rate circuit 108 computes the estimated total mass flow rate when the engine exhaust mass flow rate (e.g., volumetric flow) is above a threshold (e.g., 0.3 ACMS, 0.4 ACMS, 0.5 ACMS, etc.), or when the pressure at the outlet of the engine 20 is above a threshold (e.g., 4 kPa, 6 kPa, 8 kPa, etc.). A higher engine exhaust mass flow rate may reflect a higher delta between the estimated total mass flow rate and the engine exhaust mass flow rate, which can be used to identify an inaccuracy in the estimated mass flow rate based on pressure information. The engine exhaust mass flow rate refers to the mass flow rate measured at the outlet pipe of the engine 20 upstream from the legs.

[0119] At step 806, the controller 100 (e.g., flow rate circuit 108) determines whether the total mass flow rate of the legs is greater than or above the engine exhaust mass flow rate. In some cases, the controller 100 determines whether the total mass flow rate of the legs is greater than the engine exhaust mass flow rate by at least a predetermined value (e.g., percentage or predetermined rate). If the estimated total mass flow rate is above the engine exhaust mass flow rate, the process 800 proceeds to step 810. Having the estimated total mass flow rate greater than the engine exhaust mass flow rate reflects an imbalance flow split with the restriction downstream from the pressure sensor 16 used for estimating the mass flow rate. In this case, the estimated mass flow rate for at least one of the legs is inaccurate. Otherwise, if the estimated total mass flow rate is at or below the engine exhaust mass flow rate, the process 800 proceeds to step 808.

[0120] The total mass flow rate can be below the engine exhaust mass flow rate in cases where the mass flow leaks or slips out of certain joints of the aftertreatment system 22, thereby reducing the total mass flow rate. In some embodiments, if the total mass flow rate is below a predefined threshold (e.g., less than 80%, 90%, etc., of the expected total mass flow rate), the controller 100 may initiate a silent fault for notifying the operator via the operator I/O device 102 or transmit a signal to the service technician (e.g., inform service technician), such as to check for leaks at the next maintenance event for the system 10. [0121] At step 808, the controller 100 (e.g., correction circuit 109) determines that no correction factor is needed for the flow split based on the estimated total mass flow rate being at or below the engine exhaust mass flow rate. Having the estimated total mass flow rate at or below the engine exhaust mass flow rate reflects either a balanced flow split or an imbalance flow split with the restriction upstream from the pressure sensor 16 used for estimating the mass flow rate. Hence, even if the flow split is imbalanced, the estimated mass flow rate of each leg is accurately estimated, and the controller 100 (e.g., adjustment circuit 111) can adjust the reductant dosing rate, control hydrocarbon injection, and/or soot load estimation accordingly.

[0122] At step 810, the controller 100 (e.g., adjustment circuit 111) determines whether the SCR catalyst member 50 has been regenerated (e.g., whether regeneration is performed or in progress for the SCR catalyst member 50). If the regeneration has not been completed, at step 812, the controller 100 (e.g., adjustment circuit 111) triggers or continues regeneration of the SCR catalyst member 50. The regeneration process removes deposits or catalyst deactivated compounds (e.g., potential restrictions) and restores SCR catalyst member 50 to a predefined activity level. The controller 100 activates the regeneration process because the imbalance may be caused by deposits in the SCR catalyst member 50 of either the first or the second legs 22A- B.

[0123] In various embodiments, the controller 100 initiates a hydrocarbon dosing to regenerate at least one of a first SCR catalyst member of the first leg 22A and/or the second SCR catalyst member of the second leg 22B in response to determining that the estimated total mass flow rate is greater than the engine exhaust mass flow rate and before computing the correction factor. In some cases, the controller 100 receives an indication of whether individual SCR catalyst members 50 have been regenerated. Accordingly, the controller 100 initiates the hydrocarbon dosing to regenerate at least one of the SCR catalyst members 50 that has not been or is not in the process of regeneration. In some cases, the controller 100 initiates the hydrocarbon dosing as part of the start of process 800, such as at step 802. If the regeneration is completed, the process 800 proceeds to step 814. [0124] At step 814, similar to step 806, the controller 100 (e.g., flow rate circuit 108) determines whether the estimated total mass flow rate is above the engine exhaust mass flow rate after performing the regeneration. For example, the controller 100, subsequent to regenerating at least one of the SCR catalyst members 50 in the respective legs of the aftertreatment system 22, estimates a third mass flow rate of exhaust gas in the first leg 22A and a fourth mass flow rate of exhaust gas in the second leg 22B (e.g., computed similarly to step 804). Using the third and fourth mass flow rates, the controller 100 computes the (e.g., second) estimated total mass flow rate to compare to the engine exhaust mass flow rate. The estimated total mass flow rate may be similar to the above total mass flow rate. If the estimated total mass flow rate is still above the engine exhaust mass flow rate, the process 800 proceeds to step 818.

[0125] Otherwise, if the estimated total mass flow rate is at or below the engine exhaust mass flow rate, the process 800 proceeds to step 816. Similar to step 808, at step 816, the controller 100 may not apply a correction factor to the estimated flow split because the regeneration event resolves the imbalance between the legs (e.g., imbalance caused by SCR catalyst member 50), thereby making the estimated total mass flow rate, for instance, equal to the engine exhaust mass flow rate. As described herein, because the restriction occurred downstream from the pressure sensor 16, the controller 100 (e.g., correction circuit 109) is configured to compute a correction factor for balancing or correcting the estimated first mass flow rate and the estimated second mass flow rate computed from pressure information.

[0126] At step 818, the controller 100 determines whether the system (e.g., the aftertreatment system 22 or at least one of the legs or components of the legs of the aftertreatment system 22) is newly installed. The controller 100 determines whether the system is newly installed in response to the estimated total mass flow rate being above the engine exhaust mass flow rate, associated with at least one of steps 706 or 714. In some cases, the controller 100 determines whether the system is newly installed at the start of process 800 (at step 802). In some other cases, the controller 100 determines whether the system is newly installed after completing the regeneration event at step 810. If the system is newly installed, the process 800 proceeds to step 820. Having a newly installed system (e.g., system with relatively low engine operation hours, such as less than 50 hours, 100 hours, etc.) may indicate that the restriction is caused by the original equipment manufacturer (OEM) piping or not caused by soot load build-up or SCR deposit, considering the one or more components of the aftertreatment system 22 are also newly installed. In this case, newly installed systems with certain restrictions are due to piping differences in the systems. A system that is no longer considered a new system (e.g., the engine operation hours is greater than or equal to a predefined threshold) may have different restrictions between the legs because of accumulated ash or soot or deposit formation in certain component(s) of the aftertreatment system 22, such as soot build-up in the DPF member 40 or deposit formation in the SCR catalyst member 50 of one leg compared to the other.

[0127] At step 820, the controller 100 (e.g., correction circuit 109) computes a correction factor in response to determining that the first leg 22A or the second leg 22B is newly installed. The controller 100 computes the correction factor for a newly installed system by performing proportionality correction for the estimated mass flow rate based on catalyst outlet pressure calculated ACMS value. To perform the proportionality correction, the process 800 proceeds to step 828.

[0128] At step 828, the controller 100 (e.g., correction circuit 109) determines pressure differential values across the first SCR catalyst member in the first leg 22A and the second SCR catalyst member in the second leg 22B. The pressure differential value represents a pressure drop across the catalyst member (e.g., DPF member 40). The controller 100 determines the pressure differential value based on the difference between a first pressure value at the inlet or upstream from the catalyst member and a second pressure value at the outlet or downstream from the catalyst member. The controller 100 determines a first pressure differential value in the first leg 22A and a second pressure differential value in the second leg 22B.

[0129] At step 830, the controller 100 (e.g., correction circuit 109) computes a correction factor based on the proportion between the two pressure differential values. The proportion between the pressure differential values represents a flow split between the legs. For example, based on the proportion between the two legs using the pressure differential values, the controller 100 can determine which of the legs is the low flow leg (e.g., the leg with a relatively lower mass flow rate) and the high flow leg (e.g., the leg with a relatively higher mass flow rate). The leg corresponding to a higher pressure differential value can represent the high flow leg and the leg corresponding to a lower pressure differential value can represent the low flow leg. For example, with a relatively higher restriction downstream of the pressure sensor, such as in the first leg compared to the second leg, the pressure sensor in the first leg may measure higher back pressure induced by the higher restriction downstream of the pressure sensor in the first leg compared to the second leg. In another example, with a relatively higher restriction upstream from the pressure sensor in one leg compared to another, such as in the first leg compared to the second leg (e.g., without downstream pressure difference in this case), the pressure sensor may sense a higher pressure when there is a higher mass flow rate in the first leg. However, because there is an upstream restriction in the first leg relatively more than in the second leg, the mass flow rate in the first leg is lower than the mass flow rate in the second leg and the pressure sensor can sense lower pressure on the first leg.

[0130] In various embodiments, the correction factor is a multiplier based on the proportion between the pressure differential values (e.g., 55-45, 60-40, 65-45, etc.). The controller 100 is configured to apply the correction factor to the engine exhaust mass flow rate. Using a proportion (or mass flow split) of 60-40 as an example, the controller 100 is configured to estimate a corrected mass flow rate for the low flow leg by applying the correction factor (e.g., the lower proportion, such as 40% in this case) to the engine exhaust mass flow rate (e.g., 40% of the engine exhaust mass flow rate). In some cases, the controller 100 is configured to estimate a corrected mass flow rate for the high flow leg by applying the correction factor (e.g., the higher proportion, such as 60% in this case) to the engine exhaust mass flow rate (e.g., 60% of the engine exhaust mass flow rate). Accordingly, the controller 100 can estimate the corrected mass flow rate for each of the legs based on the proportion between the pressure differential values. The operations for computing and applying the correction factor based on the proportion between pressure differentials can be described in further detail in conjunction with at least FIG. 8, for example. [0131] Returning to step 818, the controller 100 may receive an indication or determine that neither the first or second legs 22A-B nor any components therein are newly installed. If the system is not newly installed, the process 800 proceed to step 822.

[0132] At step 822, the controller 100 (e.g., flow rate circuit 108) determines whether soot load flow rebalance has occurred or is true. The soot load flow rebalance refers to the build-up of soot in the catalyst members (e.g., the first catalyst member in the first leg 22A and the second catalyst member in the second leg 22B) over time, causing the mass flow split to be balanced. For instance, there may be an imbalance flow split in the system while the soot load is low. Because soot accumulates faster in the high flow leg (e.g., more soot traversing into the high flow leg) and slower in the low flow leg (e.g., less soot traversing into the low flow leg), the high flow leg builds up more soot load compared to the low flow leg. Over time, the soot load causes a restriction in the high flow leg comparable to the existing restriction in the low flow leg, thereby balancing the flow split between the legs of the aftertreatment system 22. Therefore, the controller 100 is configured to monitor the flow split and the soot load over time to determine whether the flow split has been balanced by the soot load build-up.

[0133] The controller 100 determines whether the soot load flow rebalance has occurred after determining that the system is not newly installed at step 818. In some cases, the controller 100 determines whether the soot load flow rebalance has occurred after determining that the estimated total mass flow rate is above the engine exhaust mass flow rate, associated with at least one of steps 706 or 714. In some other cases, the controller 100 determines whether the soot load flow rebalance has occurred after completing the regeneration event at step 810, for example.

[0134] If the controller 100 determines that the flow split is rebalanced because of soot load build-up, the process 800 proceeds to step 824. Otherwise, the process 800 proceeds to step 826. In either case, the controller 100 is configured to compute the correction factor based on the estimated soot load flow rate (e.g., mass flow rate relative to the soot load).

[0135] At step 824, the controller 100 (e.g., correction circuit 109) computes a correction factor based on the engine exhaust mass flow rate for each leg (e.g., half of the engine exhaust mass flow rate) and a virtual value of the respective leg. In this case, the correction factor is a multiplier that when applied to at least one of the estimated mass flow rates, increases or decreases the estimated mass flow rate to estimate the corrected mass flow rate. The following formula can be used to determine the correction factor:

[0136] For instance, half of the engine exhaust mass flow rate represents the desired mass flow rate for each leg. The virtual value represents the mass flow rate estimated for the respective leg based on at least one of differential pressure or catalyst out pressure information. The controller 100 computes the virtual value based on the estimated total mass flow rate and the flow split across the legs of the aftertreatment system 22. For example, if the engine exhaust mass flow rate is 50 kg/min, the controller 100 determines that each leg has 25 kg/min mass flow rate for a 50/50 flow split. If the estimated total mass flow rate is 55 kg/min with 30 kg/min for the first leg and 25 kg/min for the second leg, the controller 100 computes the correction factor of 25/30 = 0.833 for the first leg and 25/25 = 1 for the second leg. In further example, if the first leg corresponds to 32 kg/min mass flow rate and the second leg corresponds to 23 kg/min mass flow rate, the controller 100 computes the correction factors of 25/32 = 0.78 for the first leg and 25/23 = 1.08 for the second leg.

[0137] Based on the techniques described above, the controller 100 is configured to compute or estimate a first virtual mass flow rate (e.g., first virtual value) of exhaust gas in the first leg 22A based on a first pressure differential value across the first DPF member in the first leg 22A. Further, the controller 100 is configured to estimate a second virtual mass flow rate (e.g., second virtual value) of exhaust gas in the second leg 22B based on a second pressure differential value across the second DPF member in the second leg 22B. Using the respective pressure differential values for the respective legs, the controller 100 is configured to compute the correction factor (e.g., via the formula provided above) based on the engine exhaust mass flow rate and at least one of the estimated first virtual mass flow rate or the estimated second virtual mass flow rate. [0138] At step 826, the controller 100 (e.g., correction circuit 109 and/or modeling circuit 110) is configured to compute the correction factor based on a matching model if the soot load did not rebalance the flow. The process 800 proceeds to step 832 to perform a matching model-based correction factor computation.

[0139] At step 832, the controller 100 (e.g., modeling circuit 110) determines pressure differential values (e.g., first pressure differential value and second pressure differential value) across respective particulate filters (e.g., first DPF member and second DPF member) over a time window. The time window includes various time intervals representing the frequency for determining the pressure differential values. Examples of the time window and the time intervals include a 1 -minute time window with time intervals of 1 second, 5 minutes time window with time intervals of 5 seconds, among others.

[0140] At step 834, the controller 100 (e.g., modeling circuit 110) compares the pressure differential values, in each time interval, against a set of calibrated tables. The set of calibrated tables includes multiple predetermined pressure differential values representing different flow splits of the engine exhaust mass flow rate. The predetermined pressure differential values may be represented as a proportion of pressure differential values between the legs, such as 50-50 for a balanced system, 55-45, 60-40, 65-45, 70-30, etc. Each calibrated table of the set of calibrated tables is assigned a corresponding bucket for scoring the comparison.

[0141] At step 836, in each of the time intervals in the time window, the controller 100 (e.g., modeling circuit 110) is configured to increment the score for at least one of the calibrated tables in the set in response to the computed pressure differential values (e.g., first and second pressure differentia values) or the proportion of the pressure differential values being comparable to or matching the predefined pressure differential values or predefined proportion of such calibrated table. The controller 100 iterates this process for the remainder of the time window and the process 800 proceeds to step 838.

[0142] At step 838, at the end of the time window, the controller 100 (e.g., correction circuit 109) computes a correction factor for at least one of the legs of the aftertreatment system 22 based on a selected flow split corresponding to a highest scoring calibrated table in the set. For example, based on the comparisons and at the end of the time window, the controller 100 collects the scores associated with each of the calibrated tables in the set.

[0143] By comparing the score of each calibrated table against each other, the controller 100 is configured to select the calibrated table with the highest score (e.g., bucket). Further, the controller 100 selects the flow split corresponding to the highest scoring calibrated table and uses the selected flow split to compute the correction factor. Similar to the proportionality correction, the controller 100 can apply the flow split to the engine exhaust mass flow rate to estimate the corrected mass flow rate for at least one of the legs (e.g., high flow leg and/or low flow leg). In some arrangements, the controller 100 clears the scores or buckets of the calibrated tables after selecting the highest scoring calibrated table, selecting the flow split, or computing the correction factor, for example. The operations for the matching model-based correction factor can be described in further detail in conjunction with at least FIG. 10.

[0144] As described herein, the controller 100 (e.g., correction circuit 109) is configured to apply the correction factor for estimating a corrected mass flow rate. Subsequently, the controller 100 (e.g., adjustment circuit 111) is configured to adjust at least one of a reductant dosing, hydrocarbon dosing, or soot load estimation based on the corrected first mass flow rate and the corrected second mass flow rate. For instance, the controller 100 (e.g., adjustment circuit 111) can decrease the reductant dosing for one of the legs with an overestimated mass flow rate (e.g., a decrease from the estimated mass flow rate to the corrected mass flow rate). In some cases, the controller 100 can increase the reductant dosing for one of the legs with an underestimated mass flow rate (e.g., an increase from the estimated mass flow rate to the corrected mass flow rate).

[0145] In various arrangements, the controller 100 (e.g., adjustment circuit 111) is configured to adjust the hydrocarbon dosing (e.g., frequency or timing) based on the corrected mass flow rate. For example, an overestimated mass flow rate can lead to an early or premature regeneration event (e.g., hydrocarbon dosing event). By applying the correction factor to the estimated mass flow rate, the overestimation is corrected and the controller 100 can initiate the regeneration event based on the corrected mass flow rate for the respective leg (e.g., relatively less frequent or at a later time compared to when the mass flow rate is overestimated).

Similarly, after correcting an underestimated mass flow rate, the controller 100 may advance the timing or increase the frequency of the regeneration event for the associated leg with underestimated mass flow rate.

[0146] Further, the controller 100 (e.g., adjustment circuit 111) corrects the soot load estimation based on the corrected mass flow rate. For a leg having an overestimated mass flow rate, the controller 100 may decrease the soot load estimation proportional to the decrease from the estimated mass flow rate to the corrected mass flow rate of the leg. For a leg having an underestimated mass flow rate, the controller 100 may increase the soot load estimation proportional to the increase from the estimated mass flow rate to the corrected mass flow rate of the leg. Although examples herein include adjustment of the reductant dosing, hydrocarbon dosing, and soot load estimation, the controller 100 is configured to adjust or control other components of the system 10 based on the corrected mass flow rate in at least one of the legs.

[0147] FIG. 9 illustrates graphs 902-912 depicting example operations associated with a delta pressure-based correction process of FIG. 8, such as for a newly installed system. Each graph represents steps for performing proportionality correction, such as described in conjunction with at least steps 820, 828, and 830 of FIG. 8, for example. Referring to graph 902, the controller 100 (e.g., flow rate circuit 108) receives catalyst out pressure data from the pressure sensor 16 in each of the legs including the low flow leg and the high flow leg. As shown, the catalyst out pressure readings for both the low flow leg (e.g., portion 914) and the high flow leg (e.g., labeled in the legend as 65-35) are above the data points representing a balanced flow split (e.g., labled as 50-50 in the legend).

[0148] At graph 904, the controller 100 estimates the mass flow rate for each leg based on the catalyst out pressure data of graph 902. As shown, the exhaust mass flow rate is overestimated for the second leg 22B (e.g., the low flow leg, labeled in the legend as “65-35 L2”) when using the catalyst out pressure data for mass flow rate estimation. Portion 916 includes the estimated mass flow rate for the low flow leg (e.g., second leg 22B in this case), which is above the baseline mass flow rate (e.g., 50-50 data points). [0149] Subsequently, at graph 906, the controller 100 estimates the total mass flow rate based on the first leg 22A and the second leg 22B (e.g., adding the respective mass flow rates). The controller 100 determines that the estimated total mass flow rate is greater than the engine exhaust mass flow rate, as shown in portion 918. In this example, the engine exhaust mass flow rate is the baseline data point labeled as “50-50”, for example. Because the estimated total mass flow rate is greater than the engine exhaust mass flow rate, and with an indication that the system is newly installed, the controller 100 determines to perform a proportionality correction to correct the mass flow rate estimation for at least one of the leg (e.g., the low flow leg).

[0150] At graph 908, the controller 100 receives an indication that the catalyst member is cleaned (e.g., given that the system is newly installed). With respect to clean catalyst members, the controller 100 is configured to determine which of the legs is the low flow leg or the high flow leg based on delta pressure information across the catalyst member (e.g., DPF delta pressure (dp)). For example, the controller 100 receives delta pressure information across the catalyst member of the respective leg. As shown, the controller 100 identifies the high flow leg based on the catalyst delta pressure (e.g., labeled as “65-35”) being above the baseline data points. Further, the controller 100 identifies the low flow leg based on the catalyst delta pressure (e.g., in portion 920) being below the baseline data points. Hence, the controller 100 is configured to use the delta pressure across the catalyst member to identify the low flow leg and the high flow leg.

[0151] The controller 100 computes a proportion between the delta pressure of the high flow leg and the low flow leg. The proportion between the delta pressure can be used as part of the correction factor. For instance, the controller 100 applies the proportion to the engine exhaust mass flow rate. In this case, the proportion is 65% for the high flow leg and 35% for the low flow leg estimated based on the delta pressure of the respective catalyst member. The controller 100 computes a first corrected mass flow rate for the low flow leg corresponding to 35% of the engine exhaust mass flow rate and a second corrected mass flow rate for the high flow leg corresponding to 65% of the engine exhaust mass flow rate. In some cases, the controller 100 applies the proportionality correction to the pressure data (e.g., catalyst out pressure) of at least one of the legs, such that the corrected pressure data can be used to compute the corrected mass flow rate.

[0152] In various embodiments, the controller 100 is configured to disregard or skip estimating the corrected mass flow rate for the high flow leg because the pressure data for the second leg 22B may not be affected by the restriction in the low flow leg, for example. For simplicity, the controller 100 is configured to correct the mass flow rate estimation for the low flow leg without adjusting the estimated mass flow rate for the high flow leg when the high flow leg is not affected by the restriction. In other cases, the controller 100 is configured to adjust the estimated mass flow rates for both legs.

[0153] At graph 910, the controller 100 applies the correction factor to the estimated mass flow rate of the low flow leg. In some cases, applying the correction factor may include using the corrected mass flow rate computed for the respective leg. As shown in portion 922, the controller 100 applies the correction factor to the low flow leg, thereby correcting/diagnosing the overestimation of the mass flow rate for the low flow leg. In some cases, the controller 100 also applies a respective correction factor for the high flow leg to adjust the estimated mass flow rate of the second leg 22B. Compared to graph 904, the corrected mass flow rate of the low flow leg is below the baseline data points.

[0154] At graph 912, the controller 100 aggregates or adds the corrected mass flow rates to determine a corrected total mass flow rate. As shown in portion 924, in comparison to graph 906, the data points representing the corrected total mass flow rate are about the same as the data points of the engine exhaust mass flow rate. Therefore, the mass flow rates across the legs are representative of the engine exhaust mass flow rate entered in the aftertreatment system 22.

[0155] Referring now to FIG. 10, depicted is a block diagram of an example matching model 1000 associated with at least step 826 of FIG. 8. The controller 100 (e.g., correction circuit 109 and/or modeling circuit 110) is configured to use the matching model 1000 to compute a correction factor if at least the system is not newly installed and the flow split is not rebalanced by the soot load. The process for the matching model 1000 can be described in conjunction with steps 826 and 832-838 of FIG. 8. In various arrangements, the matching model 1000 may be executed continuously or periodically (e.g., at predefined time intervals or based on certain operating events of the engine 20, such as ignition of the engine, generating the exhaust byproducts, etc.).

[0156] The matching model 1000 includes an input block 1002 and a flow split calculation block 1004. The input block 1002 includes processes for receiving and aggregating input data. The input data can be used in the flow split calculation block 1004 including processes for computing the flow split of mass flow rate between the legs. The computed flow split can be monitored within a predefined time window (e.g., windows-based monitoring logic) as described herein in step 1018.

[0157] At step 1006, the controller 100 receives or determines the (e.g., total) engine exhaust mass flow rate from the engine 20. The controller 100 computes the engine exhaust mass flow rate based on a sum of fresh air flow at the inlet of the engine and the fuel flow delivered by at least one fuel injector into the combustion chamber. The fresh air flow corresponds to an inlet airflow measured by, for instance, a flow sensor or based on a sum of charge flow and EGR flow. The charge flow is computed using the PV = mRT equation (e.g., ideal gas law). The EGR flow is computed using the flow through the venturi equation. In this case, there may be a charge pressure sensor and venturi pressure sensor in the engine architecture, for example. The engine exhaust mass flow rate reflects the desired estimated total exhaust mass flow rate that splits between the legs of the aftertreatment system 22.

[0158] At step 1008, the controller 100 applies a first-order filter to the computed engine exhaust mass flow rate. The first-order filter can be a state update Kalman filter, among other types of first-order filters, such as alpha-beta filter, or moving average, among others, for example. The controller 100 determines a filtered engine exhaust mass flow rate in response to applying the filter. The formula for a Kalman filter is provided as follows: y = engine exhaust mass flow rate after applying the filter. k = incremental value as timestamp increments, suhc as 1, 2, 3, 4, etc. dt = time difference, such as 200 ms, etc. tau = a predefined time value, such as 2 seconds, 3 seconds, 5 seconds, etc.

[0159] At step 1010, the controller 100 determines the volumetric flow rate in cubic meters per second (ACMS) for at least one leg (e.g., for comparison with the pressure information used to estimate the mass flow rate in the at least one leg). The ACMS can be computed as follows: m = mass flow rate.

R = gas constant.

T = temperature in Kelvin.

P = gas pressure in KPa absolute, based on ambient pressure and/or catalyst out pressure.

[0160] At step 1012, the controller 100 retrieves or obtains various calibrated tables (e.g., sometimes referred to as models) from the memory 103 or remote database (e.g., calibrated tables described similarly to FIG. 8). Individual calibrated tables include predefined pressure information (e.g., at least one of catalyst pressure out information or pressure differential information) corresponding to respective flow splits on the engine exhaust mass flow rate. Different pressure information corresponds to different flow splits. For example, a first calibrated table may correspond to a 60-40 flow split (e.g., 60% of engine exhaust mass flow rate for a high flow leg and 40% of engine exhaust mass flow rate for a low flow leg), a second calibrated table may correspond to a 65-35 flow split, a third calibrated table may correspond to a 70-30 flow split, etc. The calibrated tables can be generated or preconfigured based on the fuel reading (e.g., injection) data, which can be used to compute the mass flow rate at the inlet of the engine 20 and/or the outlet of the engine 20. [0161] In various arrangements, the controller 100 selects or obtains at least one set of calibrated tables based on the engine exhaust mass flow rate. For example, different engine exhaust mass flow rates result in different pressure readings (e.g., catalyst out pressure data and pressure differential data) regarding each leg of the aftertreatment system 22. Therefore, each set of calibrated tables can be configured for a respective engine exhaust mass flow rate. The controller 100 selects at least one of the set of calibrated tables based on comparisons between the computed engine exhaust mass flow rate or ACMS as described in conjunction with step 1010 to the predefined engine exhaust mass flow rate associated with the respective set of calibrated tables, for example.

[0162] At step 1014, the controller 100 receives the sensed/measured catalyst out pressure information of at least one leg (e.g., a first leg 22A is used as an example) at a predetermined operating condition (e.g., fuel injection rate, reductant dosing rate, fresh air flow rate, torque request, etc.) of the engine 20 and/or the aftertreatment system 22.

[0163] At step 1016, the controller 100 applies the first-order filter to the measured catalyst out pressure of the first leg 22A (or the second leg 22B). The controller 100 uses the filtered catalyst out pressure information for comparison with the predefined pressure information from the calibrated tables (e.g., in one of the sets of calibrated tables based on the engine exhaust mass flow rate). For example, the controller 100 compares the measured pressure value sensed from at least one of the pressure sensors 16 to the predefined pressure value of each calibrated table. The controller 100 can identify at least one calibrated table having the predefined pressure value closest to the measured pressure value. The controller 100 is configured to iterate processes of steps 1002 and 1004 in each interval within a predefined time window and monitor the comparisons between the measured pressure values to the predefined pressure values at step 1018.

[0164] At step 1018, the controller 100 is configured to perform a window-based monitoring technique for monitoring the comparison of the measured pressure values to model (e.g., predefined) pressure values performed within the predefined time window. Within the time window, controller 100 tracks the number of times a respective pair of measured pressure values from the legs (e.g., pressure values from the first and second legs 22A-B) matches the model pressure values of at least one calibrated table. In response to each match, the controller 100 increments a score or a bucket corresponding to the calibrated table having the model pressure value. If the measured pressure value is between two model pressure values of different calibrated tables, the controller 100 may increase the score of both calibrated tables.

[0165] At the end of the window, the controller 100 selects the model (e.g., calibrated table) with the highest score (e.g., highest number of matches). Selecting the calibrated table can correspond to selecting a flow split corresponding to the calibrated table. The controller 100 is configured to utilize the selected flow split to compute the correction factor and correct the estimated mass flow rate of at least one leg. As described above, the controller 100 can apply the correction factor to the estimated mass flow rate or compute a corrected mass flow rate by applying the flow split to the engine exhaust mass flow rate to identify the mass flow rate traversing the high flow leg and the low flow leg.

[0166] Referring to FIG. 11, a graph 1100 depicting a model -based approach associated with at least step 826 of FIG. 8 for inlet pipe restriction is shown. The graph 1100 illustrates example cases of measured pressure values (e.g., catalyst out pressure) and estimated/computed mass flow rates for the first leg 22A and the second leg 22B of the aftertreatment system 22. Case 1 corresponds to a balanced system having a 50-50 flow split. Case 2 corresponds to a 57- 43 flow split system with an inlet pipe restriction (e.g., restriction upstream of the pressure sensor 16 used for measuring pressure information). Case 3 corresponds to a 60-40 flow split system with an inlet pipe restriction. As shown, the (e.g., precalibrated) lines in the graph 1100 represent modeled pressure values relative to modeled mass flow rates for certain calibrated tables. Lines 60 and 40 represent a calibrated table having a 60-40 flow split. Lines 57 and 43 represent a calibrated table having a 57-43 flow split. Line 50 represents a 50-50 flow split calibrated table or baseline values.

[0167] In case 2, the controller 100 determines that the data points of the first leg 22 A and the second leg 22B are aligned with the data points of the calibrated table corresponding to the 57-43 flow split. Accordingly, the controller 100 can select the 57-43 flow split to compute the correction factor. In case 3, the controller 100 may determine that the total mass flow rate is greater than the engine exhaust mass flow rate. The controller 100 is configured to correct the estimated mass flow rate for at least the low flow leg (e.g., the second leg 22B in this case). Correcting the mass flow rate can be described in conjunction with FIG. 7. Upon correcting the estimated mass flow rate, the controller 100 determines that the data points of the first leg 22 A and the second leg 22B are aligned with the data points of the calibrated table corresponding to the 40-60 outlet flow split table. In some cases, the controller 100 determines that the data points corresponding to the first leg 22A align with the 60-40 inlet flow split table, and selects the flow split without correcting the data points of the second leg 22B. Accordingly, the controller 100 can select the 60-40 flow split to compute the correction factor, for example.

[0168] Referring to FIG. 12, a graph 1200 depicting a model-based approach for tailpipe restriction is shown. Similar to graph 1200, three cases are provided, including case 1 for 50-50 flow split, case 2 for 57-43 flow split, and case 3 for 60-40 flow split. In this case, the imbalance for 57-43 flow split and 60-40 flow split is caused by a tailpipe restriction (e.g., restriction downstream from the pressure sensor 16 used for estimating the mass flow rate). As shown, the precalibrated lines for tailpipe restriction are different from the lines for inlet pipe restriction because the location of the restriction affects the pressure readings and mass flow rate estimation. In case 2, the controller 100 determines that the data points of the first leg 22 A align with the calibrated table corresponding to a 57-43 flow split (e.g., comparison between the measured values and the modeled values). The controller 100 selects the 57-43 flow split for computing the correction factor. In case 3, the controller 100 compares the measurement data points to the modeled data points and identifies an alignment with the calibrated table corresponding to a 60-40 flow split. Accordingly, the controller 100 selects the 60-40 flow split for computing the correction factor. The controller 100 can interpolate between other tables or models based on other readings from the pressure sensors 16.

[0169] FIG. 13 illustrates example graphs 1302-1308 depicting monitored data for a model -based approach of FIG. 8, matching 50-50 flow split data to a respective flow split table. The graph 1302, among other graphs of FIGS. 14-16, such as graphs 1402, 1502, and 1602, represent the predicted flow split between the legs of the aftertreatment system 22. As shown, the controller 100 is able to match the 50-50 flow split data to a 50-50 flow split table using the model -based approach of FIG. 8. The index 1 of graph 1302 represents or corresponds to the 50-50 flow split table.

[0170] FIG. 14 illustrates example graphs 1402-1408 depicting monitored data for a model -based approach of FIG. 8, matching 40-60 flow split data to a respective flow split table. As shown, the controller 100 is able to match the 40-60 flow split data to a 40-60 flow split table using the model -based approach of FIG. 8. The index 5 of graph 1402 represents or corresponds to the 40-60 inlet flow split table. In graph 1404, updates from time 500 to around time 2250 may be paused because the temperature or the exhaust gas mass flow rate minimum threshold is not satisfied.

[0171] FIG. 15 illustrates example graphs 1502-1508 depicting monitored data for a model -based approach of FIG. 8, matching 60-40 flow split data to at least one respective flow split table. As shown, the controller 100 is able to match the 60-40 flow split data to at least one of 55-45 or 60-40 flow split table using the model-based approach of FIG. 8. The index 6 of graph 1502 represents or corresponds to the 55-45 outlet flow split table and the index 8 of grpah 1502 represents or corresponds to the 60-40 outlet flow split table.

[0172] FIG. 16 illustrates example graphs 1602-1608 depicting monitored data for a model-based approach of FIG. 8, matching TC NRTC 50-50 flow split data (e.g., example mock-up data or test data) to respective flow split tables. As shown, the controller 100 is able to match the TC NRTC 50-50 flow split data to the 50-50 flow split able using the model-based approach of FIG. 8. The index 5 of graph 1602 represents or corresponds to the 50-50 flow split table. Whereas FIG. 13 depicts a steady state cycle (e.g., graph 1306), FIG. 16 depicts a transient cycle (e.g., graph 1606).

[0173] Referring now to FIG. 17, depicted is an overview process flow diagram for another example process 1700 for managing mass flow split in a multi -leg aftertreatment system of the engine system of FIG. 1, using NOx measurements. The processes, operations, or steps of FIG. 17 can be performed, operated, or executed by the components (e.g., controller 100, I/O device 120, aftertreatment system 22, sensors, etc.) of the system 10, data processing system, cloud computing environment, or any other computing devices described herein in conjunction with FIGS. 1-16. For example, additional or alternative operations of the process 1700 can be performed by one or more circuits of the controller 100. Additionally or alternatively, some operations of the process 1700 can be performed by a remote device, such as a remote data processing system. Some operations of the process 1700 may involve the controller 100 receiving data from components of the aftertreatment system 22, such as one or more sensors, and forwarding the data to the remote device for processing, or vice versa.

[0174] At step 1702, the controller (e.g., NOx circuit 107) computes a first NOx conversion efficiency of the first leg 22 A. The controller 100 computes the first NOx conversion efficiency based on a difference between the amount/level of NOx at the inlet of the first leg 22A or upstream a first catalyst member (e.g., first SCR catalyst member) and the amount of NOx at the outlet of the first leg 22 A or downstream the first catalyst member.

[0175] At step 1704, the controller (e.g., NOx circuit 107) computes a second NOx conversion efficiency of the second leg 22B. The controller 100 computes the second NOx conversion efficiency based on a difference between the amount of NOx at the inlet of the second leg 22B or upstream a second catalyst member (e.g., second SCR catalyst member) and the amount of NOx at the outlet of the second leg 22B or downstream the second catalyst member.

[0176] At step 1706, the controller (e.g., NOx circuit 107) computes an average/mean NOx conversion efficiency based on the first NOx conversion efficiency and the second NOx conversion efficiency (e.g., average between the two NOx conversion efficiencies). At step 1708, the controller (e.g., NOx circuit 107) is configured to compute a difference between the first NOx conversion efficiency and the second NOx conversion efficiency. The controller 100 is configured to compute the average NOx conversion efficiency and the difference subsequent to determining that the ammonia to NOx ratio (ANR) between the first leg 22A and the second leg 22B is similar. Having a similar ANR indicates that the legs should have similar NOx conversion efficiency. Hence, if the average NOx conversion efficiency is below a threshold or if the difference between the first NOx conversion efficiency and the second NOx conversion efficiency is greater than a threshold, this indicates that there is a restriction in the tailpipe. [0177] At step 1710, in response to determining that the average NOx conversion efficiency is less than a first threshold or the difference between the first NOx conversion efficiency and the second NOx conversion efficiency is greater than the first threshold, the controller (e.g., correction circuit 109) is configured to compute an adjustment factor for balancing an estimated first mass flow rate and an estimated second mass flow rate. The adjustment factor may be computed based on the ANR of the low NOx conversion efficiency leg. For instance, if the ANR of the low NOx conversion efficiency leg is greater than (or equal to) a threshold, this indicates that there is an ammonia slip from the low NOx conversion efficiency leg. Otherwise, if the ANR of the low NOx conversion efficiency leg is less than the threshold, this indicates that there is NOx slip from the low NOx conversion efficiency leg. The adjustment factor can be predefined based on whether there is an ammonia slip or NOx slip.

[0178] At step 1712, the controller (e.g., flow rate circuit 108 or correction circuit 109) is configured to estimate an adjusted first mass flow rate of the exhaust gas in the first leg 22A and an adjusted second mass flow rate of the exhaust gas in the second leg 22B using the adjustment factor. If there is an indication of an ammonia slip, the controller 100 estimates the adjusted mass flow rate by decreasing the estimated mass flow rate. If there is an indication of a NOx slip, the controller 100 estimates the adjusted mass flow rate by increasing the estimated mass flow rate.

[0179] At step 1714, the controller (e.g., adjustment circuit 111) is configured to adjust at least one of a reductant dosing, a hydrocarbon dosing, or a soot load estimation based on the adjusted first mass flow rate and the adjusted second mass flow rate. In various embodiments, the operations, techniques, or features of process 1700 can be described in further detail in conjunction with FIG. 18.

[0180] Referring now to FIG. 18, depicted is a process flow diagram of an example process 1800 for managing mass flow split in a multi -leg aftertreatment system associated with FIG. 17 as described in further detail. The processes, operations, or steps of FIG. 18 can be performed, operated, or executed by the components (e.g., controller 100, VO device 120, aftertreatment system 22, sensors, etc.) of the system 10, data processing system, cloud computing environment, or any other computing devices described herein in conjunction with FIGS. 1-17. For example, additional or alternative operations of the process 1800 can be performed by one or more circuits of the controller 100. Additionally or alternatively, some operations of the process 1800 can be performed by a remote device, such as a remote data processing system. Some operations of the process 1800 may involve the controller 100 receiving data from components of the aftertreatment system 22, such as one or more sensors, and forwarding the data to the remote device for processing, or vice versa.

[0181] The process 1800 starts at step 1802. The process 1800 can be performed before or after determining that the flow split is imbalanced. The process 1800 may be performed in addition to or alternative to the process 800 of FIG. 8. At step 1802, the controller 100 is configured to initiate a cleaning operation for the catalyst member (e.g., DPF member 40, SCR catalyst member 50, etc.). After the catalyst member(s) have been cleaned (e.g., removing the soot load or deposit build-up factors in regards to an imbalance system), the controller 100 proceeds to step 1804.

[0182] At step 1804, the controller 100 determines whether the average ammonia to NOx ratio (ANR) is similar between the legs. The ANR can be measured in molar, where a 1.1 molar indicates that there are 1.1 times the amount of ammonia (e.g., reductant) compared to NOx, for example. Having an ANR of around 1 (e.g., between 0.9-1.1, 0.95-1.05, 0.98-1.02, etc.) provides a desired ratio of reductant to NOx such that the amount of reductant and NOx at the tailpipe is below a desired level (e.g., in the case where the mass flow rate estimation is accurate). If the ANR between the legs is similar, the process 1800 proceeds to step 1806. Otherwise, the process 1800 remains at step 1804, and the controller 100 determines whether the ANR between the legs is similar at another time interval.

[0183] In various embodiments, in a system without restriction at the tailpipe, having a similar ANR between the legs yields an average conversion efficiency (e.g., NOx conversion efficiency between the legs) that is greater than or equal to a conversion efficiency threshold. Further, in the system without restriction at the tailpipe, having a similar ANR between the legs yields a difference between the conversion efficiencies of the first and second legs 22A-B that is less than or equal to another threshold. However, as discussed herein, if the ANR is similar between the legs and at least one of the average conversion efficiency or the difference between the conversion efficiencies is beyond the desired level (e.g., in step 1808), the controller 100 is configured to determine that there is a restriction in the tailpipe causing inaccurate estimation of mass flow rates. The inaccurate estimation of the mass flow rate results in an erroneous dosing rate of reductant. The erroneous dosing rate leads to at least one of NOx slip or reductant slip (e.g., ammonia slip). The NOx or reductant slip corresponds to an amount of NOx or reductant at the tailpipe that is above a desired level. Hence, as discussed herein, the conversion efficiency of the legs can be used to determine whether there is a restriction in the tailpipe and compute an adjustment factor to correct/adjust the estimated mass flow rate and/or the dosing rate of the reductant.

[0184] In some cases, the system 10 may be implemented or configured with ammonia sensors (not shown). The ammonia sensors can be positioned downstream of the catalyst member (e.g., DPF member 40, SCR catalyst member 50, etc.) of the respective legs. The ammonia sensors may be positioned at the tailpipe of the respective legs. In this case, with a similar ANR between the legs, the controller 100 is configured to monitor the difference in the level of ammonia and/or NOx (e.g., using the ammonia sensor or NOx sensor 12) between each leg. If the difference between the legs is greater than or beyond a threshold, the controller 100 determines that there is a restriction in the tailpipe in at least one of the legs which leads to the erroneous mass flow rate estimation. Similar to using the NOx conversion efficiency, the controller 100 may compute the adjustment factor using the level of reductant or NOx slip for correcting the estimated mass flow rate or dosing rate, for example.

[0185] At step 1806, the controller 100 (e.g., NOx circuit 107) is configured to calculate/compute the mean or average NOx conversion efficiency (CE) between the first leg 22A and the second leg 22B. To compute the average, the controller 100 is configured to compute a first NOx conversion efficiency of the first leg 22A and a second NOx conversion efficiency of the second leg 22B. The NOx conversion efficiency of each leg is determined based on the difference between the amount of NOx at the inlet of the leg and the amount of NOx at the outlet of the leg. The controller 100 computes the average NOx conversion efficiency based on the first and second NOx conversion efficiencies. Further, the controller 100 is configured to compute a difference in NOx conversion efficiencies between the legs. [0186] At step 1808, the controller 100 (e.g., NOx circuit 107) determines whether the average conversion efficiency is less than a threshold (e.g., a first threshold) or the difference between the NOx conversion efficiencies is greater than the threshold. For example, the threshold for the average conversion efficiency can be 80%, 85%, 90%, etc. The threshold for the difference between NOx conversion efficiency can be 10%, 15%, 20%, etc. If at least one of the conditions is true, the process 1800 proceeds to step 1810. Otherwise, if both conditions are false, the process 1800 proceeds to step 1832.

[0187] At step 1810, the controller 100 receives a sample estimated mass flow rate of each leg for correction adjustment (e.g., to be corrected/adjusted using an adjustment factor). The controller 100 (e.g., flow rate circuit 108) may estimate the mass flow rate of each leg based on pressure information (e.g., catalyst out pressure or pressure differential). In some cases, the controller 100 receives the estimated mass flow rate from a remote computing system that processed the pressure data or other data related to the mass flow rate.

[0188] In various arrangements, the controller 100 (e.g., NOx circuit 107) is configured to compare the computed first NOx conversion efficiency of the first leg 22A to the computed second NOx conversion efficiency of the second leg 22B. Based on the comparison, the controller 100 determines which of the leg have a lower NOx conversion efficiency. The leg with the lower NOx conversion efficiency may be referred to as a low conversion efficiency leg (e.g., low NOx conversion efficiency leg). Further, the controller 100 determines the ANR. of the low conversion efficiency leg.

[0189] At step 1812, the controller 100 (e.g., NOx circuit 107) compares the ANR. of the low conversion efficiency leg to a predetermined threshold (e.g., a second threshold). This threshold represents can be predefined by the administrator of the system 10 or configured via the operator I/O device 120. The threshold may be predefined as 1 molar, 1.1 molar, 0.9 molar, among others. For example, an ANR. of less than 0.9 for the low conversion efficiency leg (e.g., less than 80% conversion efficiency) can indicate NOx slip at the tailpipe. In another example, an ANR. of 1.3 for the low conversion efficiency leg (e.g., less than 85%-90% conversion efficiency) can indicate NH ₃ slip at the tailpipe. The comparison of the ANR. of the low conversion efficiency leg to the threshold represents whether a NOx slip or ammonia slip has occurred. For instance, if the ANR of the low conversion efficiency leg is greater than (or in some cases equal to) the threshold, the controller 100 determines that there is an ammonia slip from the low conversion efficiency leg because the proportion of ammonia is higher than the proportion of NOx in the ANR. In this case, the process 1800 proceeds to step 1814. Conversely, if the ANR is less than the threshold, the controller 100 determines that there is a NOx slip from the low conversion efficiency leg because the proportion of ammonia is lower than the proportion of NOx in the ANR. In response to identifying or determining that there is a NOx slip from the low conversion efficiency leg, the process 1800 proceeds to step 1816.

[0190] At step 1814, the controller 100 (e.g., adjustment circuit 111) is configured to adjust the dosing rate of reductant based on ammonia slip from the low conversion efficiency leg. For instance, the controller 100 can decrease the dosing rate because of the ammonia slip (e.g., caused by overdosage of the reductant). In this case, the overdosing of reductant is due to an overestimation of the mass flow rate. The controller 100 can use a predetermined adjustment factor to decrease the estimated mass flow rate of the low conversion efficiency leg (e.g., referred to as an adjusted mass flow rate). For example, a correction factor (e.g., correction multiplication factor) of 1.1 can be initially used to increase the mass flow rate or a correction factor of 0.9 can be initially used to decrease the mass flow rate. In response to the adjustment, the controller 100 decreases the dosing rate of the reductant proportional to the decrease in the estimated mass flow rate. In some cases, the controller 100 is configured to decrease the dosing rate by a predetermined amount in response to the ammonia slip. The predetermined amount may be configured by the administrator of the system 10, such as decreasing the dosing rate by 10%, 20%, 30%, etc., or by a predetermined rate. In this scenario, the dosing rate or the estimated mass flow rate of the other leg, different from the low conversion efficiency leg, may not be adjusted because the erroneous estimation is on the low conversion efficiency leg.

[0191] At step 1816, in response to determining that the ANR of the low conversion efficiency leg is below the threshold, the controller 100 is configured to adjust the dosing rate of the reductant by increasing the dosing rate. Having a low ANR (e.g., ANR below the threshold) for the low conversion efficiency leg indicates that there is a NOx slip in the low conversion efficiency leg. Hence, the controller 100 is configured to increase the dosing rate by a predetermined amount in response to the NOx slip.

[0192] The NOx slip may be a result of an underestimated mass flow rate. In this case, in response to determining that the average conversion efficiency is less than the threshold (e.g., first threshold) or the difference between the conversion efficiencies of the legs (e.g., first and second NOx conversion efficiencies) is greater than the threshold, the controller 100 is configured to compute an adjustment factor for balancing at least one of the estimated first mass flow rate for the first leg 22A or an estimated second mass flow rate for the second leg 22B. The adjustment factor may be predetermined by the administrator, such as to decrease the estimated mass flow rate in the case of ammonia slip and increase the estimated mass flow rate in the case of NOx slip. In this case, the controller 100 applies the adjustment factor to the estimated mass flow rate of the low conversion efficiency leg to increase the reductant dosing rate based on NOx slip. In response to the adjustment, the controller 100 is configured to increase the reductant dosing rate based on the increased (e.g., adjusted) mass flow rate.

[0193] At step 1818, the controller 100 (e.g., NOx circuit 107) is configured to determine whether the low conversion efficiency leg is improving subsequent to applying the adjustment factor or adjusting the dosing rate of the reductant. To determine whether the low conversion efficiency leg is improving, the controller 100 computes a third NOx conversion efficiency of the low NOx conversion efficiency leg subsequent to adjusting the dosing rate of the reductant. The controller 100 compares the third NOx conversion efficiency to a threshold (e.g., third threshold), which may be similar to the threshold described in steps 1608 or 1612. If the third conversion efficiency is less than the threshold, the low conversion efficiency leg is not improving, and the process 1800 proceeds to step 1822. If the third conversion efficiency is greater than or equal to the threshold, the low conversion efficiency leg is improving, and the process 1800 proceeds to step 1820.

[0194] In various arrangements, to determine whether the low conversion efficiency leg is improving, the controller 100 compares the ANR. (e.g., new ANR.) of the low conversion efficiency leg after adjusting the dosing rate to the threshold (e.g., third threshold). The threshold can be based on the ANR. of the low conversion efficiency leg prior to the adjustment, such as a predefined percentage or amount of improvement from the prior ANR. The threshold can be a conversion efficiency threshold. In some cases, the controller 100 compares the new ANR against the previous ANR CE determine whether to maintain the correction factor. The controller 100 can apply one or more subsequent correction factors until the prior value(s) increases to the desired threshold.

[0195] At step 1820, the controller 100 is configured to reset a value regarding the number of iterations the dosing rate re-adjustment has been performed (e.g., incremented in step 1822). The process 1800 proceeds to step 1832 after resetting this value.

[0196] At step 1822, the controller 100 determines that the low conversion efficiency leg is not improving because of incorrect adjustment (e.g., direction or amount of adjustment). The controller 100 increments a value representing the number of iterations that the dosing rate has been adjusted (e.g., in this case, the value = 1 after the increment).

[0197] At step 1824, the controller 100 determines whether the dosing rate of the reductant has been adjusted once. If the dosing rate has been adjusted once (e.g., value = 1), the process 1800 proceeds to step 1826. Otherwise, if the dosing rate has been adjusted more than once (e.g., value > 1), the process 1800 proceeds to step 1828, for example.

[0198] At step 1826, the controller 100 re-adjust the dosing rate of the reductant in response to determining that the low conversion efficiency leg has not improved subsequent to the initial adjustment. The controller 100 is configured to adjust the dosing rate by a predetermined amount. Because the dosing rate may be overadjusted, the controller 100 is configured to re-adjust the dosing by reducing the initial adjustment amount. For example, if the dosing rate has been increased (e.g., in step 1816), the controller 100 is configured to decrease the adjusted dosing rate proportional to the increased amount (e.g., half, third, quarter, etc. of the increased amount). In some cases, the controller 100 reapplies or replaces the initial adjustment factor with a different adjustment factor to adjust the estimated mass flow rate. The second adjustment factor may be less than the initial adjustment factor, such that the correction step is reduced (e.g., the dosing rate is increased by a lower amount). [0199] In another example, if the dosing rate has been decreased (e.g., in step 1814), the controller 100 is configured to increase the adjusted dosing rate proportional to the decreased amount (e.g., half, third, quarter, etc. of the decreased amount). In some cases, the controller 100 reapplies or replaces the initial adjustment factor with a different adjustment factor to adjust the estimated mass flow rate. The second adjustment factor may be less than the initial adjustment factor, such that the correction step is reduced (e.g., the dosing rate is decreased by a lower amount).

[0200] Referring back to step 1818, the controller 100 determines whether the low conversion efficiency leg has improved after re-adjusting the dosing rate of the reductant (e.g., reducing the correction step). To perform this determination, the controller 100 computes a fourth NOx conversion efficiency of the low conversion efficiency leg and compares the fourth NOx conversion efficiency to another threshold (e.g., fourth threshold). The threshold may be similar to or different from the third threshold. In some cases, the controller 100 determines the ANR of the low conversion efficiency leg after the re-adjustment. If the low conversion efficiency leg has improved (e.g., improvement in the NOx conversion efficiency or ANR), the process 1800 proceeds to step 1820. If the low conversion efficiency leg still has not improved, the process 1800 proceeds to step 1822, and the value is incremented. In this step, because the value is greater than 1, the process proceeds to step 1828.

[0201] At step 1828, the controller 100 resets the correction adjustment (e.g., the adjustment of the dosing rate) and the value regarding the number of adjustments made to the dosing rate.

[0202] At step 1830, the controller 100 triggers a fault and proceeds to step 1832. The controller 100 triggers the fault in response to determining that the fourth NOx conversion efficiency is less than the fourth threshold. Triggering the fault can include the controller 100 transmitting a signal or a message to the operator I/O device 120 indicating that there is a restriction or an imbalance in the aftertreatment system 22 and to visit a service center. In some cases, the signal or message may be transmitted to a device of the service center for diagnostic or to schedule a service appointment, for example. In certain cases, the triggered fault may be a service light on the dashboard of the vehicle including the system 10. [0203] At step 1832, the controller 100 is configured to pause or stop the operations in process 1800 and restart the operation by proceeding to step 1804. In some cases, if the imbalance is diagnosed or resolved (e.g., esimated mass flow rate is corrected) after another iteration of the process 1800, the controller 100 can reset the triggered fault. In various embodiments, by adjusting or correcting the estimated mass flow rate, the controller 100 is configured to further adjust the at least one of the hydrocarbon dosing or the soot load estimation based on the adjusted mass flow rate of at least one of the legs.

[0204] In various embodiments, in response to addressing the ANR and/or the conversion efficiency of the low conversion efficiency leg, the low conversion efficiency leg becomes the high (or normal) conversion efficiency leg, and the other leg may be the low conversion efficiency leg. The process 1800 may be reiterated for the other leg (e.g., correcting the estimated mass flow rate of the other leg).

[0205] Referring to FIG. 19, graphs of an example process 1900 for NOx monitoringbased correction associated with FIG. 18 are shown. Graph 1902 shows increases in the engine exhaust mass flow rate at various time intervals. Graph 1904 shows increases in the bed temperature of a catalyst member (e.g., SCR catalyst member 50) corresponding to the increased engine exhaust mass flow rate at various time intervals. The sudden increase in temperature can cause ammonia slip at the tailpipe of the respective leg. The sudden increase in the engine exhaust mass flow rate and catalyst temperature may be because of mass flow rate estimation error with tailpipe restriction.

[0206] As shown in graph 1906, the conversion efficiencies (e.g., of the SCR catalyst member 50) between the two legs and the ANR can be used as the conditions indicative of an imbalance system. For instance, at a timeframe between 4.26 hour and 4.29 hour, the conversion efficiencies of the two legs (e.g., the average conversion efficiency) are below a predetermined threshold (e.g., below 95%, 90%, etc.) or the difference between the conversion efficiencies is greater than or equal to a threshold (e.g., greater than 3%, 5%, etc.). Further, in the same timeframe, the ANR is similar between the first and second legs 22A-B (e.g., around 1-1.25). Satisfying the conditions indicate that the mass flow rate estimation is erroneous with the restriction at the tailpipe. [0207] Graph 1908 shows the NOx measurements (e.g., in parts per million (ppm)) and graph 1910 shows reductant dosage (e.g., estimated by the controller 100 or measured by an ammonia sensor) during the same timeframe as graph 1906. As shown, given the NOx level, the second leg 22B provides an excessive amount of reductant compared to the NOx level traversing the system.

[0208] Graph 1912 shows the mass flow rate estimated in the same time window as graphs 1906-1910. As shown, the estimated mass flow rate for both the first and second leg 22B increased from 9 kg/min to 20-22 kg/min at around 4.24-4.25 hours. In this case, the estimated mass flow rate is inaccurate for at least one of the legs due to tailpipe restriction. Hence, the controller 100 is configured to perform the operations described in process 1800 to correct the estimated mass flow rate and adjust the dosing rate of the reductant to minimize NOx and reductant slip. In this case, the second leg 22B is the low flow leg but is estimated as the high flow leg, while the first leg 22A is the high flow leg but is estimated as the low flow leg, relative to the second leg 22B.

[0209] Graph 1914 shows the adjusted estimated mass flow rates after applying an adjustment/correction factor to the first leg 22A and/or the second leg 22B. For example, there is a reductant slip from the second leg 22B because of the overestimated mass flow rate, and ammonia slip in the first leg 22A because of the underestimatd mass flow rate. In this case, the correction factor applied to the legs includes decreasing the estimated mass flow rate for the second leg 22B and increasing the estimated mass flow rate for the first leg 22A by a predetermined amount proportional to the overestimation or underestimation of the estimated mass flow rate. The amount of overestimation or underestimation can be based on the level of NOx slip or reductant slip.

[0210] Graph 1916 shows the reductant dosing rate and graph 1918 shows the measured NOx level in the same time window as graph 1914 after the adjustment. As shown, the reductant dosage amount has been improved after applying the adjustment/correction factor. Based on the improved results from the correction, further correction may be initiated (e.g., increase the adjustment factor) or the correction can be maintained. Accordingly, as shown in graph 1920, the conversion effciency is improved for the first leg 22 A and the second leg 22B after applying the adjustment factor.

III. Construction of Example Embodiments

[0211] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed but rather as descriptions of features specific to particular embodiments. Certain features described in this specification in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0212] As utilized herein, the terms “substantially,” generally,” “approximately,” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

[0213] The terms “coupled” and the like, as used herein, mean the joining of two components directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two components or the two components and any additional intermediate components being integrally formed as a single unitary body with one another, with the two components, or with the two components and any additional intermediate components being attached to one another. [0214] The terms “fluidly coupled to” and the like, as used herein, mean the two components or objects have a pathway formed between the two components or objects in which a fluid, such as air, exhaust gas, liquid reductant, gaseous reductant, aqueous reductant, gaseous ammonia, etc., may flow, either with or without intervening components or objects. Examples of fluid couplings or configurations for enabling fluid communication may include piping, channels, or any other suitable components for enabling the flow of a fluid from one component or object to another.

[0215] It is important to note that the construction and arrangement of the system shown in the various example embodiments is illustrative only and not restrictive in character. All changes and modifications that come within the spirit and/or scope of the described embodiments are desired to be protected. It should be understood that some features may not be necessary, and embodiments lacking the various features may be contemplated as within the scope of the application, the scope being defined by the claims that follow. When the language “a portion” is used, the item can include a portion and/or the entire item unless specifically stated to the contrary.

[0216] Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, Z, X and Y, X and Z, Y and Z, or

X, Y, and Z (i.e., any combination of X, Y, and Z). Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of

Y, and at least one of Z to each be present, unless otherwise indicated.

[0217] Additionally, the use of ranges of values (e.g., W to P, etc.) herein are inclusive of their maximum values and minimum values (e.g., W to P includes W and includes P, etc.), unless otherwise indicated. Furthermore, a range of values (e.g., W to P, etc.) does not necessarily require the inclusion of intermediate values within the range of values (e.g., W to P can include only W and P, etc.), unless otherwise indicated.