Sensor configuration for a post-treatment system comprising an SCR with filter

Abstract

Exhaust aftertreatment system, comprehensive: an oxidation catalyst configured to absorb exhaust gas from an engine; a selective catalytic reduction catalyst (204) with filter (SCR with filter) positioned downstream of the oxidation catalyst; a hydrocarbon metering device (212) configured to inject hydrocarbons into a stream of exhaust gas upstream of the oxidation catalyst; a reducing agent dosing unit (214) configured to inject reducing agent into the exhaust gas stream upstream of the SCR with filter and downstream of the oxidation catalyst; an aftertreatment control unit (216) operationally coupled to the hydrocarbon metering unit, wherein the aftertreatment control unit is configured to control a metering rate at which the hydrocarbon metering unit (212) injects hydrocarbons into the exhaust gas stream to cause regeneration of the SCR (204) with filter; a first temperature sensor (218) positioned near an outlet of the oxidation catalyst, wherein the first temperature sensor (218) is in operational communication with the aftertreatment control unit (216); and a second temperature sensor (220) positioned near an inlet of the SCR (204) with filter, the second temperature sensor being in operational communication with the aftertreatment control unit, the post-treatment control unit (216) is further configured as follows: to determine an initial temperature measurement via operational communication with the additional temperature sensor (218), to determine a second temperature measurement via operational communication with the temperature sensor, to determine an error between the second temperature measurement and a target regeneration temperature of the SCR with filter and to adjust the outlet target temperature of the oxidation catalyst in order to minimize the error.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to the field of exhaust aftertreatment systems. BACKGROUND

[0002] Generally, regulated emissions for internal combustion engines include carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter. However, such regulations have become stricter in recent years. For example, the regulated emissions for NO x The emissions and particulate matter from diesel engines are so low that in many cases, emission levels cannot be met with improved combustion technologies alone. For this reason, exhaust aftertreatment systems are increasingly being used to reduce the proportion of harmful exhaust emissions present in the exhaust.

[0003] Conventional exhaust aftertreatment systems include any number of different components to reduce the levels of regulated pollutants present in the exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered engines include various components such as a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR) catalyst, a diesel particulate filter (DPF), an SCR with filter, and / or an ammonia slip catalyst (ASC) (also referred to as an ammonia oxidation catalyst (AMOX)). Each of the DOC, SCR catalyst, DPF, SCR with filter, and ASC components is configured to perform a specific exhaust emission treatment process on the exhaust gas flowing through or over the respective components.

[0004] Generally, DOCs reduce the amount of CO and hydrocarbons present in the exhaust gas via oxidation techniques and also convert NO to NO2 for passive regeneration of soot on a DPF and to facilitate rapid SCR reactions. DPFs filter particulates, including soot, present in the exhaust gas. SCR catalysts and SCR systems with a filter are designed to remove NO x from the exhaust gas, which is relatively more difficult to remove than CO, hydrocarbons and particulate matter.

[0005] SCR catalysts are configured to NO x (NO and NO2 in small amounts) into nitrogen (N2) and water vapor (H2O). A reducing agent (usually ammonia (NH3) in some form) is added to the exhaust gas before the catalyst. The NO x and NH3 flow over the catalyst and a catalytic reaction takes place in which NO xand NH3 are converted into N2 and H2O. An SCR with filter represents an assembly that performs the combined functions of an SCR and a DPF.

[0006] In many conventional SCR systems and SCR systems with a filter, NH3 is used as a reductant. Typically, pure NH3 is not used directly due to safety concerns, cost, weight, lack of infrastructure, and other factors. Instead, many conventional systems use diesel exhaust fluid (DEF), which is typically a urea-water solution. To convert the DEF to NH3, the DEF is injected into a decomposition tube through which an exhaust stream flows. The injected DEF spray is heated by the exhaust stream to vaporize the urea-water solution and trigger the decomposition of urea into NH3. The exhaust mixture, including the NH3 obtained from the decomposition of the urea, is further mixed as it flows through the decomposition tube and flows over the SCR catalyst, where the NO x and NH3 are mainly converted into N2 and H2O.

[0007] An exhaust gas treatment system for an internal combustion engine is known from US 2014 / 0 311 123 A1. The system includes an exhaust conduit extending from the engine and configured to receive an exhaust gas flow from the engine, a first injector in fluid communication with the exhaust conduit and configured to selectively inject fuel containing unburned hydrocarbon (HC) into the exhaust conduit, and an oxidation catalyst disposed in the exhaust conduit downstream of the first injector.The system further includes a hydrocarbon selective catalytic reduction (HC-SCR) catalyst applied to the oxidation catalyst, a heating device positioned on an upstream side of the oxidation catalyst and configured to heat the oxidation catalyst and the HC-SCR catalyst, a selective catalytic reduction (SCR) device disposed in the exhaust conduit downstream of the oxidation catalyst, and a particulate filter positioned downstream of the selective catalytic reduction device.

[0008] From US 2011 / 0 271 657 A1, an engine control system is known comprising an injection determination module and an injection distribution module. The injection determination module determines a desired amount of hydrocarbons (HC) to be injected into exhaust gas generated by an engine for regenerating a particulate matter (PM) filter. The injection distribution module controls a ratio of boost injection to post-combustion injection based on engine load, engine speed, and the desired amount of HC injection, wherein boost injection comprises injection of HC into the exhaust gas, and wherein post-combustion injection comprises injection of HC into cylinders of the engine during a period following combustion.

[0009] From US 2013 / 0 139 490 A1, a method for determining an exhaust system state is known, which comprises determining whether a reaction in an oxidation catalyst is operating acceptably based on a determined temperature of the exhaust gas flowing from the oxidation catalyst and determining a temperature of the exhaust gas flowing from a particulate filter. The method further comprises determining a temperature of the exhaust gas flowing into the oxidation catalyst, determining an exhaust system state based on a first difference between the temperature of the exhaust gas flowing from the particulate filter and the temperature of the exhaust gas flowing from the oxidation catalyst and a second absolute difference between the temperature of the exhaust gas flowing from the oxidation catalyst and the temperature of the exhaust gas flowing into the oxidation catalyst, and communicating a signal to establish the determined exhaust system state. SUMMARY

[0010] Various embodiments relate to exhaust aftertreatment systems. An exemplary exhaust aftertreatment system includes an oxidation catalyst in exhaust-receiving communication with an engine. A selective catalytic reduction catalyst with a filter is positioned downstream of the oxidation catalyst. A hydrocarbon doser is configured to inject hydrocarbons into a stream of exhaust gas upstream of the oxidation catalyst. A reductant doser is configured to inject reductant into the stream of exhaust gas upstream of the SCR with a filter and downstream of the oxidation catalyst. An aftertreatment controller is operatively coupled to the hydrocarbon doser. The aftertreatment controller is configured to control a dosing rate at which the hydrocarbon doser injects hydrocarbons into the stream of exhaust gas to cause regeneration of the SCR with a filter.

[0011] In some implementations, the system further includes a first temperature sensor positioned near an outlet of the oxidation catalyst and a second temperature sensor positioned near an inlet of the SCR with filter. The first temperature sensor and the second temperature sensor are in operative communication with the aftertreatment control unit. The control unit is further configured to determine a first temperature reading via operative communication with the first temperature sensor and a second temperature reading via operative communication with the second temperature sensor. The control unit is also configured to determine an error between the second temperature reading and a target regeneration temperature of the SCR with filter and adjust a target oxidation catalyst outlet temperature to minimize the error.In some implementations, the controller is further configured to determine a third temperature reading via operative communication with the second temperature sensor, wherein the third temperature reading is equal to the first temperature reading. The controller is further configured to determine a delay time between a first time at which the first temperature reading is determined and a second time at which the third temperature reading is determined, and to determine a reductant deposition value based on the delay time. In some implementations, the dosing rate of the hydrocarbon doser is controlled to cause the first temperature reading to be equal to the oxidation catalyst outlet target temperature. In some implementations, the dosing rate of the hydrocarbon doser is further based on a mass flow rate of the exhaust gas or an ambient temperature.In some implementations, the reductant comprises a diesel exhaust fluid. In some implementations, the hydrocarbon doser is configured to inject the hydrocarbons into a cylinder of the engine. In some implementations, the aftertreatment control unit is further configured to detect a formation of solid reductant deposits within the exhaust aftertreatment system. In some implementations, the system further includes a first differential pressure sensor positioned above the SCR with filter and in operative communication with the aftertreatment control unit. The control unit is further configured to determine a first differential pressure reading via operative communication with the first differential pressure sensor and to determine a soot load value based on the first differential pressure reading.In some implementations, the system further includes a second differential pressure sensor positioned above a portion of the exhaust aftertreatment system that includes the reductant doser and in operative communication with the aftertreatment control unit. The control unit is further configured to determine a second differential pressure reading via operative communication with the second differential pressure sensor and to determine a reductant deposition value based on the second differential pressure reading.

[0012] Another implementation relates to an aftertreatment control unit that includes a filter regeneration circuit. The filter regeneration circuit is configured to determine a first temperature reading via operative communication with a first temperature sensor and a second temperature reading via operative communication with a second temperature sensor. The first temperature sensor is positioned near an outlet of an oxidation catalyst, and the second temperature sensor is positioned near an inlet of an SCR with filter. The filter regeneration circuit is further configured to determine an error between the second temperature reading and a target regeneration temperature of the SCR with filter and adjust a target outlet temperature of the oxidation catalyst to minimize the error.The filter regeneration circuit is further configured to control a dosing rate at which the hydrocarbon doser injects hydrocarbons into a stream of exhaust gas to cause regeneration of the SCR with filter based on the adjusted oxidation catalyst outlet target temperature.

[0013] In some implementations, the aftertreatment control unit further includes a DEF deposit detection circuit. The DEF deposit detection circuit is configured to determine a third temperature reading via operative communication with the second temperature sensor, wherein the third temperature reading is equal to the first temperature reading. The DEF deposit detection circuit is configured to determine a delay time between a first time at which the first temperature reading is determined and a second time at which the third temperature reading is determined, and to determine a reductant deposit value based on the delay time. In some implementations, the dosing rate of the hydrocarbon doser is controlled to cause the first temperature reading to be equal to the oxidation catalyst outlet target temperature.In some implementations, the dosing rate of the hydrocarbon doser is further based on a mass flow rate of the exhaust gas or an ambient temperature. In some implementations, the aftertreatment control unit further includes a soot loading circuit. The soot loading circuit is configured to determine a first differential pressure reading via operative communication with a first differential pressure sensor, the first differential pressure sensor positioned across the SCR with filter. The soot loading circuit is further configured to determine a soot loading value based on the first differential pressure reading. In some implementations, the aftertreatment control unit includes a DEF deposit detection circuit.The DEF deposit detection circuit is configured to determine a second differential pressure reading via operative communication with a second differential pressure sensor, the second differential pressure sensor positioned over a portion of the exhaust aftertreatment system that includes the reductant doser. The DEF deposit detection circuit is further configured to determine a reductant deposit value based on the second differential pressure reading.

[0014] Yet another implementation relates to an exhaust aftertreatment system including an oxidation catalyst, a selective catalytic reduction catalyst with a filter, a hydrocarbon doser, a first temperature sensor, a second temperature sensor, and an aftertreatment control unit. The oxidation catalyst is in exhaust gas receiving communication with an engine. The selective catalytic reduction catalyst with a filter (SCR with a filter) is positioned downstream of the oxidation catalyst. The hydrocarbon doser is configured to inject hydrocarbons into a stream of exhaust gas upstream of the oxidation catalyst. The first temperature sensor is positioned near an outlet of the oxidation catalyst. The second temperature sensor is positioned near an inlet of the SCR with a filter.The aftertreatment control unit is operatively coupled to the hydrocarbon doser, the first temperature sensor, and the second temperature sensor. The aftertreatment control unit is configured to determine a first temperature reading via operational communication with the first temperature sensor and a second temperature reading via operational communication with the second temperature sensor. The aftertreatment control unit is further configured to determine an error between the second temperature reading and a target regeneration temperature of the SCR with filter and adjust a target outlet temperature of the oxidation catalyst to minimize the error.The aftertreatment control unit is further configured to control a dosing rate at which the hydrocarbon doser injects hydrocarbons into the stream of exhaust gas to cause regeneration of the SCR with filter based on the adjusted oxidation catalyst outlet target temperature.

[0015] In some implementations, the system further includes a first differential pressure sensor positioned above the SCR with filter and a second differential pressure sensor positioned above a portion of the exhaust aftertreatment system that includes a reductant doser. The first differential pressure sensor and the second differential pressure sensor are in operative communication with the aftertreatment control unit. The aftertreatment control unit is further configured to determine a first differential pressure reading via operative communication with the first differential pressure sensor, determine a soot loading value based on the first differential pressure reading, determine a second differential pressure reading via operative communication with the second differential pressure sensor, and determine a reductant deposition value based on the second differential pressure reading.

[0016] These and other features, as well as the organization and manner of operation, will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which like elements have like reference numerals throughout the various drawings described below. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic diagram illustrating an engine and an exhaust aftertreatment system including an SCR catalyst. Fig. 2A is a schematic diagram illustrating an engine and exhaust aftertreatment system including an SCR with filter according to one embodiment. Fig. 2B is a schematic diagram illustrating an exhaust aftertreatment system according to an alternative embodiment of the exhaust aftertreatment system of Fig. 2A illustrates. Fig. 3 is a block diagram showing the function and structure of the aftertreatment control unit of Fig. 2A and Fig. 2B according to one embodiment. Fig. 4 is a flowchart of a method for controlling active regeneration of an SCR with filter according to one embodiment. DETAILED DESCRIPTION

[0017] An SCR with filter represents an exhaust aftertreatment component technology that combines the functionality of a fine dust filter (e.g. conventionally performed by a DPF) and a NO x-reduction (e.g., conventionally performed by an SCR catalyst) is integrated into a single SCR with filter unit. The inclusion of SCR with filter units in exhaust aftertreatment systems impacts various aspects of the systems, including system architecture and control strategy. For example, aftertreatment control systems manage various functionalities, such as reductant (e.g., DEF) dosing, SCR / SCR with filter performance diagnostics, DPF / SCR with filter temperature control for regeneration, soot load estimation (SLE)), DEF deposit detection, NH3 slip detection, etc. However, aftertreatment systems that include an SCR with filter unit require different sensor configurations and control strategies than conventional aftertreatment systems that include a DPF and an SCR catalyst.

[0018] Fig. 1 is a schematic diagram illustrating an engine 100 and an exhaust aftertreatment system 102 including an SCR catalyst 104. Generally, the exhaust aftertreatment system 102 is configured to remove various regulated, i.e., regulated, contaminants present in the exhaust gas. The exhaust aftertreatment system 102 is in exhaust communication with the engine 100. Several exhaust aftertreatment components are positioned within an exhaust flow path 106 defined by the exhaust aftertreatment system 102. For example, as shown in Fig. 1, the exhaust aftertreatment system 102 includes a DOC 108, a DPF 110, the SCR catalyst 104, and an AMOX catalyst 112 arranged in that order along the exhaust flow path 106, with the DOC 108 being the most upstream (closest to the engine 100) and the AMOX catalyst 112 being the most downstream (farthest from the engine 100). In other words, exhaust gas from the engine 100 flows through the DOC 108, then through the DPF 110, then through the SCR catalyst 104, and finally through the AMOX catalyst 112.

[0019] Generally, DPFs incorporate filter surfaces (e.g., ceramic or sintered metal) to remove particulate matter, such as soot particles, from the exhaust gas. From time to time, particulate matter accumulates in the DPF and must be removed. In other words, the DPF must be "regenerated." DPFs are regenerated by oxidizing (i.e., burning off) the particulate matter that has accumulated in the filter. The carbon particles beneath the particulate matter are oxidized with oxygen present in the exhaust gas to form CO2. Generally, temperatures above 500 degrees Celsius are required to achieve sufficient rates of particulate oxidation with oxygen, with the oxidation rate being highly dependent on the temperature and the amount of precious metal applied to the DPF. Additionally, at lower temperatures (e.g., approximately 200 to 450 degrees Celsius), soot particles are oxidized with NO2 (generated, for example, by the DOC or within a catalytic converter DPF).

[0020] The temperatures required for oxygen regeneration are typically not reached during normal vehicle operation. Therefore, various control strategies can be implemented to initiate "active" regeneration by raising the exhaust gas temperature. For example, among other ways, active regeneration can be initiated by injecting hydrocarbons (e.g., diesel fuel, gasoline, etc.) into the exhaust stream (e.g., secondary or post-injection), throttling intake air, adjusting the exhaust gas recovery (EGR) rate, injecting excess fuel, and using electrical heating systems. For example, in some systems, a DOC can act as a "catalytic burner" by initiating an exothermic reaction with unburned hydrocarbons in the exhaust stream, thereby increasing the temperature of exhaust gas entering the DPF.

[0021] The exhaust aftertreatment system 102 also includes a hydrocarbon doser 114 and a reductant doser 116. The hydrocarbon doser 114 is configured to inject hydrocarbons into the exhaust flow path 106 upstream of the DOC 108. The injected hydrocarbons are configured to oxidize at the DOC 108 to raise the temperature of the exhaust gas flowing therethrough. The temperature of the exhaust gas is periodically raised to initiate active regeneration of the DPF 110.

[0022] The exhaust aftertreatment system further includes an electronic aftertreatment control unit 118 in operative communication with various sensors, such as a temperature sensor 120 and a differential pressure sensor 122. Other embodiments may further include additional sensors, such as gauge pressure and / or absolute pressure sensors, NO x-Sensors, NH3 sensors, O2(Lambda) sensors, flow rate sensors, etc. As in Fig. 1, the temperature sensor 120 is positioned at an outlet of the DOC 108, and the differential pressure sensor 122 is positioned above / along the DPF 110. In other configurations, more or fewer sensors may be used in the same or a different arrangement than in Fig. 1. For example, in some configurations, mixing chamber temperature sensors may be used instead of inlet and / or outlet temperature sensors, or two pressure sensors may be used instead of a differential pressure sensor.

[0023] The aftertreatment control unit 118 may be configured to control active regeneration of the DPF 110. As mentioned above, active regeneration generally occurs on the DPF 110 at temperatures above approximately 400 to 500 degrees Celsius. The temperature of the DPF 110 is dependent on the temperature of the exhaust gas entering the DPF 110. The DOC 108 may trigger an exothermic reaction with unburned hydrocarbons in the exhaust stream (e.g., injected by the hydrocarbon doser 114), thereby increasing the temperature of the exhaust gas entering the DPF.

[0024] Fig. Figure 2A is a schematic diagram illustrating an engine 200 and an exhaust aftertreatment system 202 including an SCR with filter 204 according to one embodiment. The engine 200 may be a compression-ignition engine or a spark-ignition engine, and may be powered by any of a variety of fuels, such as diesel, natural gas, gasoline, etc. Generally, the exhaust aftertreatment system 202 is configured to remove various regulated emissions present in the exhaust.

[0025] The exhaust aftertreatment system 202 is fluidly coupled (e.g., in exhaust communication) to the engine 200. A plurality of exhaust aftertreatment components are positioned within an exhaust flow path 206 defined by the exhaust aftertreatment system 202. For example, as shown in Fig. As illustrated in Figure 2A, the exhaust aftertreatment system 202 includes a DOC 208, the SCR with filter 204, and an AMOX catalyst 210 arranged in that order along the exhaust flow path 206, with the DOC 208 being the most upstream (closest to the engine 200) and the AMOX catalyst 210 being the most downstream (farthest from the engine 200). In other words, exhaust gas from the engine 200 flows through the DOC 208, then through the SCR with filter 204, and finally through the AMOX catalyst 210. The DOC 208 may be a diesel oxidation catalyst or another type of oxidation catalyst.

[0026] The exhaust aftertreatment system 202 also includes a hydrocarbon doser 212 and a reductant doser 214. In the Fig. 2A, the reductant doser 214 is a DEF doser configured to inject or introduce DEF into the exhaust flow path 206. It should be understood that other embodiments may use pure NH3 or reductants other than DEF. The hydrocarbon doser 212 may be mounted on an exhaust pipe defining the exhaust flow path 206. In one embodiment, the hydrocarbon doser 212 is configured to inject hydrocarbons into the exhaust flow path 206 above the DOC 208. The injected hydrocarbons are configured to oxidize at the DOC 208 to raise the temperature of the exhaust gas flowing therethrough. The temperature of the exhaust gas is periodically raised to initiate active regeneration of the SCR with filter 204.

[0027] In some embodiments, in-cylinder dosing may be used instead of hydrocarbon dosing via hydrocarbon doser 212 to raise the temperature of the exhaust gas to initiate active regeneration of the SCR with filter 204. In-cylinder dosing refers to causing the fuel injectors to inject a dose of fuel into the cylinder(s) of the engine 200 after primary combustion has occurred. Unburned fuel is expelled from the cylinder and through the exhaust flow path 206. Similar to the above, the excess fuel is configured to oxidize over / at the DOC 208 to raise the temperature of the exhaust gas flowing therethrough. The heated exhaust gas is configured to initiate active regeneration of the SCR with filter 204.All systems and methods described herein, including hydrocarbon dosing via the hydrocarbon doser 212, may also be equally applied using in-cylinder dosing.

[0028] The exhaust aftertreatment system 202 further includes an aftertreatment control unit 216 communicatively coupled to the aftertreatment system 202. Communication between and among the components may occur via any number of wired or wireless connections. For example, a wired connection may be 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 (WLAN), cellular units, radio, etc. In one embodiment, a Controller Area Network ("CAN") bus provides for the exchange of signals, information, and / or data. The CAN bus includes any number of wired and wireless connections.Because the control unit 216 is communicatively coupled to the systems and components in the aftertreatment system 202, the control unit 216 is structured to receive data from one or more of the systems and components described in . Fig. 2A. The system operating data may be received via one or more sensors (e.g., first and second temperature sensors 218, 220 and first, second, third, and fourth pressure sensors 222, 224, 226, 228) or other sensors mounted on the components of Fig. 2A. As described more fully herein, due to the integration of the control unit 216 with the components of Fig. 2A, the control unit 216 may acquire this data to adjust the hydrocarbon dosing of the hydrocarbon doser 212 to achieve substantially different operating characteristics of one or more system operating parameters, such as the active regeneration of the SCR with filter 204.

[0029] Since the components of Fig. 2A embodied in the aftertreatment system 202, the control unit 216 may be structured as an electronic control module (“ECM”). The ECM may include an engine control unit and any other control unit included in a vehicle (e.g., a transmission control unit, powertrain control unit, etc.).

[0030] As briefly mentioned above, the aftertreatment system 202 includes the first and second temperature sensors 218, 220, the first, second, and third pressure sensors 222, 224, 226, and the first and second differential pressure sensors 228, 230. Other embodiments may further include additional sensors, such as NO x -Sensors and NH3 sensors. As in Fig. 2, the first temperature sensor 218 and the first pressure sensor 222 are positioned at an outlet of the DOC 208; the second pressure sensor 224 is positioned upstream of the reductant doser 214; the second temperature sensor 220 and the third pressure sensor 226 are positioned at an inlet of the SCR with filter 204; the first differential pressure sensor 228 is positioned above the reductant doser 214, and the second differential pressure sensor 230 is positioned above the SCR with filter 204. The first, second, and third pressure sensors 222, 224, 226 may be gauge or absolute pressure sensors. In other embodiments, the sensors may be positioned and configured differently than those shown in Fig. 2A. Some embodiments include more or fewer sensors than those shown in Fig. 2A. Some embodiments may not include the second temperature sensor 220 and may instead infer the temperature at the inlet of the SCR with filter 204 based on measurements from the first temperature sensor 218 positioned at the outlet of the DOC 208. Some embodiments may include a pressure sensor (e.g., a gauge or absolute pressure sensor) at the outlet of the SCR with filter instead of, or in addition to, the third pressure sensor 226. Furthermore, some embodiments may include mixing chamber sensors instead of the inlet and / or outlet sensors. For example, instead of the second temperature sensor 220, an embodiment may include a mixing chamber temperature sensor of the SCR with filter 204 embedded within the catalyst bed of the SCR with filter 204.

[0031] Fig. 2B is a schematic diagram illustrating an exhaust aftertreatment system 232, which is an alternative embodiment of the exhaust aftertreatment system 202 of Fig. 2A. The exhaust aftertreatment system 232 of Fig. 2B is similar to the exhaust aftertreatment system 202 of Fig. 2A. The exhaust aftertreatment system 232 of Fig. However, FIG. 2B further includes an SCR catalyst 234 positioned downstream of the SCR with filter 204 and upstream of the AMOX catalyst 210. The exhaust aftertreatment system 232 further includes a third temperature sensor 236 positioned at the outlet of the SCR with filter 204 and a fourth temperature sensor positioned at the outlet of the AMOX catalyst 210. In an alternative embodiment, the SCR catalyst 234 is positioned upstream of the SCR with filter 204. In this arrangement, a temperature sensor may be included between the SCR catalyst 234 and the SCR with filter 204.

[0032] Fig. 3 is a block diagram illustrating the function and structure of the aftertreatment control unit 216 of Fig. 2A and B, according to one embodiment. The control unit 216 includes a processing circuit 302, which includes a processor 304 and a memory 306. The memory 306 may store data and / or computer code to enable the various processes described herein. Thus, the memory 306 may be communicatively coupled to the control unit 216 and may provide the control unit 216 with computer code or instructions for carrying out the processes described herein with respect to the control unit 216. Furthermore, the memory 306 may be or include tangible, non-transient volatile memory or non-volatile memory.

[0033] Memory 306 is shown including various modules for performing the activities described herein. More specifically, memory 306 includes a filter regeneration module 308, a soot loading module 310, a DEF deposit detection module 312, and an engine output (EO) NO x -Sensor compensation module 314. While in Fig. 3, various modules with particular functionality are shown, it should be understood that the control unit 216 and memory 306 may include any number of modules for performing the functions described herein. For example, the activities of multiple modules may be combined as a single module, additional modules with additional functionality may be included, etc. Further, it should be understood that the control unit 216 may control other vehicle activities beyond the scope of the present disclosure.

[0034] Certain operations of the control unit 216 described herein include operations to interpret and / or determine one or more parameters. The interpretation or determination, as used herein, includes receiving values ​​via a method known in the art, including at least receiving values ​​from a data link or network communication, receiving an electronic signal (e.g.,a voltage, frequency, current, or PWM signal) indicative of the value; receiving a computer-generated parameter indicative of the value; reading the value from a memory location on a non-transitory computer-readable storage medium; receiving the value as a runtime parameter via means already known in the art; and / or receiving a value from which the interpreted parameter can be calculated; and / or by referencing a standard value that is interpreted as a parameter value. For example, the aftertreatment control unit 216 may receive temperature measurement signals 316 from each of the first and second temperature sensors 218, 220 and determine the corresponding temperature measurement values ​​based on the respective temperature measurement signals.Likewise, the aftertreatment control unit 216 may receive pressure measurement signals 318 from each of the first, second, third pressure sensors 222, 224, 226, as well as differential pressure measurement signals from each of the first and second differential pressure sensors 228, 230, and determine the corresponding pressure measurement values ​​based on the respective pressure and differential pressure measurement signals.

[0035] The filter regeneration module 308 is structured to control the active regeneration of the SCR with filter 204. Similar to the DPF 110 of Fig. 1, active regeneration generally occurs on the SCR with filter 204 at temperatures above approximately 400 to 500 degrees Celsius. The temperature of the SCR with filter 204 is dependent on the temperature of the exhaust gas entering the SCR with filter 204. The temperature of the exhaust gas can be controlled in a variety of ways. For example, the exhaust gas temperature can be controlled, among other ways, by injecting hydrocarbons into the exhaust stream (e.g., secondary or post injection). For example, in some systems, the DOC 208 can initiate an exothermic reaction with unburned hydrocarbons in the exhaust stream (e.g., injected by the hydrocarbon doser 212), thereby increasing the exhaust gas temperature.

[0036] Filter regeneration control strategies differ for the exhaust aftertreatment system 202 from Fig. 2A and Fig. 2B, which includes the SCR with filter 204, from those of the exhaust aftertreatment system 102 of Fig. 1, which includes the SCR catalyst 104. In the exhaust aftertreatment system 102 of Fig. 1, the outlet of the DOC 108 is near the inlet of the DPF 110, so the outlet temperature of the DOC 108 is approximately equal to the inlet temperature of the DPF 110. Therefore, the aftertreatment control unit 118 may use the monitored outlet temperature of the DOC 108 (e.g., via operational communication with the temperature sensor 120) as a control parameter to control hydrocarbon dosing from the hydrocarbon doser 114 to achieve a target regeneration temperature of the DPF 110.

[0037] In contrast, the aftertreatment system 202 of Fig. 2A and Fig. 2B, the outlet of the DOC 208 is not close to the inlet of the SCR with filter 204 (the particulate filter). For example, a DEF decomposition tube (not shown) must be located between the DOC outlet and the inlet of the SCR with filter. The DEF decomposition configuration can be designed to be compact or non-compact. Because in both situations the outlet of the DOC 208 is not close to the SCR with filter 204, the temperature of the exhaust gas may drop between the outlet of the DOC 208 and the inlet of the SCR with filter 204. The difference would be more significant in a non-compact configuration. Therefore, the measured outlet temperature of the DOC 208 may not be sufficient to be used to accurately control hydrocarbon dosing from the hydrocarbon doser 114 to control the regeneration of the SCR with filter 204.In addition to the temperature drop, the distance between the DOC 208 and the SCR with filter 204 causes an inherent time delay in controlling hydrocarbon dosing upstream of the DOC 208 based on the mass flow rate of the exhaust gas in the exhaust flow path 206 to achieve a target regeneration temperature of the SCR with filter 204.

[0038] According to various embodiments, the filter regeneration module 308 controls the regeneration of the SCR with filter 204 based on one or both of the outlet temperature of the DOC 208 and the inlet temperature of the SCR with filter 204. The aftertreatment control unit 216 is structured to determine the outlet temperature value of the DOC 208 via operative communication with the first temperature sensor 218. The aftertreatment control unit 216 is also structured to determine the inlet temperature of the SCR with filter 204 via operative communication with the second temperature sensor 220.

[0039] The filter regeneration module 308 controls hydrocarbon dosing from the hydrocarbon doser 212 based on two target temperatures: a DOC 208 outlet target temperature and a SCR with filter 204 target regeneration temperature. More specifically, the DOC 208 outlet target temperature represents a dynamic target that is adjusted based on a measured error between the SCR with filter 204 inlet temperature and the target regeneration temperature. Accordingly, the dynamically adjusted DOC 208 outlet target temperature compensates for the temperature drop between the DOC 208 outlet and the SCR with filter 204 inlet. In operation, the hydrocarbon dosing from the hydrocarbon doser 212 is dynamically adjusted based on the dynamically adjusted DOC 208 outlet target temperature to cause the SCR with filter 204 inlet temperature to be equal to the target regeneration temperature.

[0040] The filter regeneration module 308 may also control hydrocarbon dosing from the hydrocarbon doser 212 based on the exhaust mass flow rate to account for the time delay between hydrocarbon dosing and its corresponding effect on the inlet temperature of the SCR with filter 204. In some embodiments, the filter regeneration module 308 further compensates for fluctuations in the ambient temperature. For example, an adaptive time scale, ranging from tens of minutes to a number of hours, may be used to monitor and account for changes in the ambient temperature, which may also affect the inlet temperature of the SCR with filter 204.

[0041] In another embodiment, the filter regeneration module 308 controls the regeneration of the SCR with filter 204 based on one of the outlet temperature of the DOC 208 and the inlet temperature of the SCR with filter 204 and a model configured to predict the temperature drop and lag between the outlet of the DOC 208 and the inlet of the SCR with filter 204. The model is configured to estimate ambient heat losses as well as thermal lag due to heating and cooling of the exhaust gas in the exhaust flow path 206 between the outlet of the DOC 208 and the inlet of the SCR with filter 204 and the effect of DEF evaporation. In one embodiment, the filter regeneration module 308 is configured to predict the inlet temperature of the SCR with filter 204 based on the measured outlet temperature value of the DOC 208 via operative communication with the first temperature sensor 218.In another embodiment, the filter regeneration module 308 is configured to predict the outlet temperature of the DOC 208 based on the measured inlet temperature of the SCR with filter 204 via operative communication with the second temperature sensor 220.

[0042] The soot load module 310 is structured to detect the amount of soot collected on the SCR with filter 204. During operation, the filter portion of the SCR with filter 204 collects particulate matter, such as soot, from the exhaust gas, which may cause an increase in exhaust backpressure. The soot load may be used, for example, to trigger regeneration of the SCR with filter 204 via the filter regeneration module 308.

[0043] According to various embodiments, the soot load module 310 is configured to determine a delta pressure-based soot load estimate (DPSLE) based on a measured differential pressure across the SCR with filter 204. The differential pressure across the SCR with filter 204 may be calculated by the soot load module 310 via operational communication with the second differential pressure sensor 230.

[0044] The DEF deposit detection module 312 is structured to detect the formation of solid DEF deposits on the interior walls of the exhaust passage and / or the decomposition tube (not shown). DEF deposits may form due to insufficient decomposition and mixing of injected DEF. For example, low-temperature regions within the exhaust flow path 206 may result in insufficient mixing or decomposition, which may lead to the formation of solid DEF deposits. DEF deposits may also form due to the DEF spray being deflected from the intended target. The formation of solid DEF deposits may result in a lower amount of NH3 concentration and lower NH3 distribution uniformity at the inlet side of the SCR with filter 204, which may degrade the performance and control of the SCR with filter 204.Additionally, solid DEF deposits may increase exhaust backpressure within the aftertreatment system 202, which may adversely impact the performance of the engine 200 and the aftertreatment system 202. Upon detecting DEF deposits, the aftertreatment control unit 216 may perform cleaning or regeneration procedures to remove the DEF deposits.

[0045] DEF deposit detection strategies differ for the exhaust aftertreatment system 202 from Fig. 2A and Fig. 2B, which includes the SCR with filter 204, from those of the exhaust aftertreatment system 102 of Fig. 1, which includes the SCR catalyst 104. For example, for the exhaust aftertreatment system 102 of Fig. 1, the absolute pressure at the outlet of the DPF 110 is conventionally used (e.g., via operational communication with the differential pressure sensor 122) to detect DEF deposits. For the exhaust aftertreatment system 202 of Fig. 2A and Fig. 2B, the primary differential pressure sensor—second differential pressure sensor 230—is located downstream of potential DEF deposit formations. To this end, in some embodiments, DEF deposit detection module 312 may further consider a pressure differential across reductant doser 214 via operational communication with first differential pressure sensor 228. DEF deposit detection module 312 may further utilize an EFA model to account for an expected pressure loss through the DEF dosing system. Alternatively, DEF deposit detection module 312 may consider an absolute pressure directly upstream of reductant dosing system 214 via operational communication with second pressure sensor 224. This pressure could be used in combination with a differential pressure measurement across SCR with filter 204 to determine whether a significant DEF deposit is present.

[0046] The DEF deposit detection module 312 may further monitor a correlation between the outlet temperature of the DOC 208 and the inlet temperature of the SCR with filter 204. The lag between the outlet temperature of the DOC 208 and the inlet temperature of the SCR with filter 204 may indicate DEF deposit formation. In one embodiment, if the lag exceeds a predetermined value, the aftertreatment controller 216 may perform purge or regeneration procedures to remove the DEF deposits. In some embodiments, in addition to the temperature lag, the pressure differential across the entire aftertreatment system 202 is analyzed to detect DEF deposit formation.

[0047] The EO-NO x -Sensor compensation module 314 is structured, an EO-NO x -determination to account for various effects of the aftertreatment system 202 on NO x -level to be taken into account. EO-NO x-Sensor compensation strategies differ for the exhaust aftertreatment system 202 from Fig. 2A and Fig. 2B, which includes the SCR with filter 204, from those of the exhaust aftertreatment system 102 of Fig. 1, which includes the SCR catalyst 104. For example, for the exhaust aftertreatment system 102 of Fig. 1 the absolute pressure at the outlet of the DPF 110 and / or the differential pressure across the DPF 110 for the EO-NO x -Sensor compensation is used (e.g., via operational communication with the differential pressure sensor 122). The differential pressure across the DOC 108 and the inlet cone of the DOC 108 is typically estimated based on the volumetric exhaust flow rate. The estimated differential pressure is used to determine the EO-NO x -Sensor measurements to compensate.

[0048] For the exhaust aftertreatment system 202 from Fig. 2A and Fig. 2B, however, the primary absolute or gauge pressure measurement is located via operational communication with the third pressure sensor 226 at the inlet of the SCR with filter 204. Since the SCR with filter 204 is downstream of the reductant dosing system 214, the EO-NO x -Sensor compensation module configured, the EO-NO x-determination to account for the reductant dosing system 214 as well as the inlet and outlet cones of the DOC 208 and the DOC 208 itself. In one embodiment, two EFA-based models are developed. A first EFA model is for the reductant dosing system 214, and a second EFA-based model is for the DOC 208 including its inlet and outlet cones. The absolute pressure is measured at the inlet of the SCR with filter 204 via the third pressure sensor 226 and not at the outlet. Measuring the absolute pressure at the inlet of the SCR with filter 204 reduces the uncertainty compared to measuring the absolute pressure at the outlet. The absolute pressure measurement is then used to calculate the EO-NO x -Sensor measurements to compensate.

[0049] Fig. 4 is a flowchart of a method for controlling active regeneration of an SCR with a filter according to one embodiment. The method 400 is described with respect to the exhaust aftertreatment system 202 of Fig. 2A and Fig. 2B. However, method 400 may equally be performed by other exhaust aftertreatment systems.

[0050] At 402, the outlet temperature of the DOC 208 and the inlet temperature of the SCR with filter are measured. More specifically, the aftertreatment control unit 216 is structured to determine the outlet temperature value of the DOC 208 via operational communication with the first temperature sensor 218 and to determine the inlet temperature of the SCR with filter 204 via operational communication with the second temperature sensor 220.

[0051] At 404, an error between the SCR with filter inlet temperature value 204 and a target SCR with filter regeneration value is calculated or otherwise determined. The target SCR with filter regeneration value may be a temperature at which the SCR with filter undergoes active regeneration.

[0052] At 406, an outlet target temperature of the DOC 208 is dynamically adjusted to minimize the error calculated at 404. Finally, at 408, hydrocarbon dosing from the hydrocarbon doser 212 is controlled to cause the outlet temperature of the DOC 208 to be equal to the outlet target temperature of the DOC 208.

[0053] It should be noted that, although described with respect to a particular method, the processes of the methods described herein can be used in other methods. It should further be noted that the term "example," as used herein to describe various embodiments, is intended to indicate that such embodiments are possible examples, representations, and / or illustrations of possible embodiments (and that such a term is not intended to imply that such embodiments are necessarily exceptional or superior examples).

[0054] Exemplary and non-limiting module implementation elements include sensors (e.g., connected to the components and / or systems in Fig. 1 and Fig.2 coupled) that provide any value specified herein, sensors that provide any value that is a precursor to any value specified herein, datalink and / or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers and / or transceivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a specific non-transient state configured according to the module specification, any actuator including at least one electrical, hydraulic or pneumatic actuator, a solenoid, an operational amplifier, analog control elements (springs, filters, integrators, adders, dividers, gain elements) and / or digital control elements.

[0055] The schematic flowcharts and schematic process diagrams described above are generally embodied as logical flowcharts. As such, the illustrated sequence and marked steps represent representative embodiments. Other steps, sequences, and processes are contemplated that are equivalent in function, logic, or effects to one or more steps or substeps of the processes illustrated in the schematic diagrams.

[0056] Furthermore, the format and symbols employed are intended to explain the logical steps of the schematic diagrams and are not intended to limit the scope of the methods illustrated by the diagrams. Although various types of arrows and lines may be used in the schematic diagrams, they are not intended to limit the scope of the corresponding methods. Indeed, some arrows or other connections may be used to indicate only the logical flow of a method. For example, an arrow may indicate a wait or monitoring time of unspecified duration between enumerated steps of an illustrated method. Furthermore, the order in which a particular method occurs may or may not exactly match the order of the corresponding steps shown.It should also be noted that each block of the block diagrams and / or flowcharts, and each combination of blocks in the block diagrams and / or flowcharts, may be implemented by special-purpose hardware-based systems that perform the specified functions or operations, or combinations of hardware and special-purpose programming code.

[0057] Many of the functional units described in this specification have been marked as modules to further emphasize their implementation independence. For example, a module can be implemented as a hardware circuit comprising custom VLSI or general-purpose circuits, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module can also be implemented in programmable hardware units, such as field-programmable general-purpose circuits, programmable logic circuits, programmable logic units, or the like.

[0058] Modules can also be implemented in a machine-readable medium for execution by various types of processors. For example, an identified module of executable code may comprise one or more physical or logical blocks of computer instructions, organized, for example, as an object, process, procedure, or function. However, the executable files of an identified module need not be physically located together, but may comprise distinct instructions stored in different locations that, when logically linked together, comprise the module and achieve the stated purpose for the module.

[0059] Indeed, a module of computer-readable program code may be a single instruction or many instructions, and it may even be distributed across several different code sections, across different programs, and across multiple storage devices. Likewise, operational data may be identified and exemplified within modules herein and may be expressed in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data stream or may be distributed across different locations, including across different storage devices, and may exist, at least in part, solely as electronic signals on a system or network.If a module or parts of a module are implemented in a machine-readable medium (or computer-readable medium), the computer-readable program code can be stored in and / or transferred to one or more computer-readable media.

[0060] The computer-readable medium may be a tangible computer-readable storage medium that stores the computer-readable program code. The computer-readable storage medium may be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor-based system, device, or apparatus, or any suitable combination of the foregoing.

[0061] More specific examples of a computer-readable medium may include, but are not limited to, a portable computer diskette, a hard disk, RAM memory, ROM memory, erasable programmable read-only memory (EPROM or flash memory), a portable read-only compact disc (CD-ROM), a versatile digital disc (DVD), an optical storage device, a magnetic storage device, a holographic storage device, a micromechanical storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium capable of containing or storing computer-readable program code for use by and / or in connection with an instruction execution system, device, or apparatus.

[0062] The computer-readable medium may also be a computer-readable signal medium. A computer-readable signal medium may include a propagated data signal with computer-readable program code embodied therein, for example, on baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of different forms, including, but not limited to, electrical, electromagnetic, magnetic, optical, or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium, other than a computer-readable storage medium, that can communicate, propagate, or transport computer-readable program code for use by, or in connection with, an instruction execution system, device, or apparatus.Computer-readable program code embedded in a computer-readable signal medium may be transmitted using any suitable medium, including, but not limited to, wireless, wired, fiber optic cable, radio frequency (RF), or the like, or any suitable combination of the foregoing.

[0063] In one embodiment, the computer-readable medium may comprise a combination of one or more computer-readable storage media and one or more computer-readable signal media. For example, computer-readable program code may be transmitted as an electromagnetic signal through a fiber optic cable for execution by a processor, or stored in a RAM memory device for execution by the processor.

[0064] Computer-readable program code for performing operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Smalltalk, C++, or the like, and conventional procedural programming languages ​​such as the "C" programming language or similar programming languages. The computer-readable program code may operate entirely on the user's computer, partially on the user's computer, as a stand-alone computer-readable package, partially on the user's computer and partially on a remote computer, or entirely on the remote computer or server.In the latter scenario, the remote computer may be connected to the user's computer over any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be to an external computer (for example, over the Internet using an Internet service provider).

[0065] The program code may also be stored in a computer-readable medium that can control a computer, other programmable data processing apparatus, or other devices to operate in a particular manner such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions that implement the function or operation specified in the schematic flow diagrams and / or the block or blocks of the schematic block diagrams.

Claims

[1] Exhaust aftertreatment system, comprising: an oxidation catalyst configured to receive exhaust gas from an engine; a selective catalytic reduction catalyst (204) with filter (SCR with filter) positioned downstream of the oxidation catalyst; a hydrocarbon doser (212) configured to inject hydrocarbons into a stream of exhaust gas upstream of the oxidation catalyst; a reductant doser (214) configured to inject reductant into the exhaust gas stream upstream of the SCR with filter and downstream of the oxidation catalyst; an aftertreatment control unit (216) operatively coupled to the hydrocarbon doser, the aftertreatment control unit configured to control a dosing rate at which the hydrocarbon doser (212) injects hydrocarbons into the stream of exhaust gas to cause regeneration of the SCR (204) with filter; a first temperature sensor (218) positioned near an outlet of the oxidation catalyst, the first temperature sensor (218) being in operative communication with the aftertreatment control unit (216); and a second temperature sensor (220) positioned near an inlet of the SCR (204) with filter, the second temperature sensor being in operative communication with the aftertreatment control unit, wherein the aftertreatment control unit (216) is further configured: to determine a first temperature measurement value via operational communication with the additional temperature sensor (218), to determine a second temperature measurement value via operational communication with the temperature sensor, to determine an error between the second temperature measurement value and a target regeneration temperature of the SCR with filter and adjust an oxidation catalyst outlet target temperature to minimize the error. [2] The exhaust aftertreatment system of claim 1, wherein the aftertreatment control unit (216) is further configured: to determine a third temperature measurement value via operational communication with the second temperature sensor (220), wherein the third temperature measurement value is equal to the first temperature measurement value, to determine a delay time between a first time at which the first temperature measurement value is determined and a second time at which the third temperature measurement value is determined, and to determine a reducing agent deposit value based on the delay time. [3] The exhaust aftertreatment system of claim 1, wherein the dosing rate of the hydrocarbon doser (212) is controlled to cause the first temperature measurement to be equal to the oxidation catalyst outlet target temperature. [4] The exhaust aftertreatment system of claim 3, wherein the dosing rate of the hydrocarbon doser (212) is further based on a mass flow rate of the exhaust gas stream. [5] The exhaust aftertreatment system of claim 4, wherein the dosing rate of the hydrocarbon doser (212) is further based on an ambient temperature. [6] The exhaust aftertreatment system of claim 1, wherein the reducing agent comprises a diesel exhaust fluid. [7] The exhaust aftertreatment system of claim 1, wherein the hydrocarbon doser (212) is configured to inject the hydrocarbons into a cylinder of the engine (200). [8] The exhaust aftertreatment system of claim 1, wherein the aftertreatment control unit (216) is further configured to detect a formation of solid reductant deposits within the exhaust aftertreatment system. [9] The exhaust aftertreatment system of claim 1, further comprising: a first differential pressure sensor (228) positioned across the SCR with filter, the first differential pressure sensor being in operative communication with the aftertreatment control unit (216); wherein the aftertreatment control unit is further configured: to determine a first differential pressure measurement value via operational communication with the first differential pressure sensor (228) and to determine a soot load value based on the first differential pressure measurement. [10] Exhaust aftertreatment system according to claim 9, further comprising: a second differential pressure sensor (230) positioned over a portion of the exhaust aftertreatment system that includes the reductant doser (214), the second differential pressure sensor (230) being in operative communication with the aftertreatment control unit (216); wherein the aftertreatment control unit (216) is further configured: to determine a second differential pressure measurement value via operational communication with the second differential pressure sensor (230) and to determine a soot deposition value based on the second differential pressure measurement. [11] The exhaust aftertreatment system of claim 1, wherein the hydrocarbon doser (212) comprises a fuel injector of the engine (200) configured to inject a dose of the hydrocarbons into a cylinder of the engine after primary combustion has occurred. [12] An aftertreatment control unit for an exhaust aftertreatment system, the aftertreatment control unit comprising: a filter regeneration circuit configured: to determine a first temperature measurement value via operational communication with a first temperature sensor (218) and to determine a second temperature measurement value via operational communication with a second temperature sensor (220), wherein the first temperature sensor (218) is positioned near an outlet of an oxidation catalyst, wherein the second temperature sensor (220) is positioned near an inlet of an SCR (204) with a filter; determine an error between the second temperature measurement value and a target regeneration temperature of the SCR (204) with filter; adjust an oxidation catalyst outlet target temperature to minimize the error; and to control a dosing rate at which a hydrocarbon doser (212) injects hydrocarbons into a stream of exhaust gas to cause regeneration of the SCR (204) with filter based on the adjusted oxidation catalyst outlet target temperature. [13] The aftertreatment control unit of claim 12, further comprising a diesel exhaust fluid (DEF) deposit detection circuit configured to: to determine a third temperature measurement value via operational communication with the second temperature sensor (220), wherein the third temperature measurement value is equal to the first temperature measurement value, to determine a delay time between a first time at which the first temperature measurement value is determined and a second time at which the third temperature measurement value is determined, and to determine a reducing agent deposit value based on the delay time. [14] The aftertreatment control unit of claim 12, wherein the dosing rate of the hydrocarbon doser (212) is controlled to cause the first temperature measurement to be equal to the oxidation catalyst outlet target temperature. [15] The aftertreatment control unit of claim 12, wherein the dosing rate of the hydrocarbon doser (212) is further based on a mass flow rate of the exhaust gas stream. [16] The aftertreatment control unit of claim 12, wherein the dosing rate of the hydrocarbon doser (212) is further based on an ambient temperature. [17] The aftertreatment control unit of claim 12, further comprising a soot loading circuit configured: to determine a first differential pressure measurement value via operational communication with a first differential pressure sensor (228), wherein the first differential pressure sensor (228) is positioned above the SCR (204) with filter; and to determine a soot load value based on the first differential pressure measurement. [18] The aftertreatment control unit of claim 17, further comprising a diesel exhaust fluid (DEF) deposit detection circuit configured to: determine a second differential pressure measurement value via operational communication with a second differential pressure sensor (230), wherein the second differential pressure sensor (230) is positioned over a portion of the exhaust aftertreatment system that includes the reductant doser (214); and to determine a soot deposition value based on the second differential pressure measurement. [19] Exhaust aftertreatment system, comprising: an oxidation catalyst configured to receive exhaust gas from an engine; a selective catalytic reduction catalyst (204) with filter (SCR with filter) positioned downstream of the oxidation catalyst; a hydrocarbon doser (212) configured to inject hydrocarbons into a stream of exhaust gas upstream of the oxidation catalyst; a first temperature sensor (218) positioned near an outlet of the oxidation catalyst; a second temperature sensor (220) positioned near an inlet of the SCR (204) with filter; and an aftertreatment control unit (216) operatively coupled to the hydrocarbon doser (212), the first temperature sensor (218) and the second temperature sensor (220), wherein the aftertreatment control unit (216) is configured: determine a first temperature measurement value via operational communication with the first temperature sensor (218) and a second temperature measurement value via operational communication with the second temperature sensor (220); determine an error between the second temperature measurement value and a target regeneration temperature of the SCR (204) with filter; adjust an oxidation catalyst outlet target temperature to minimize the error; and to control a dosing rate at which the hydrocarbon doser injects hydrocarbons into the exhaust gas stream to cause regeneration of the SCR (204) with filter based on the adjusted oxidation catalyst outlet target temperature. [20] The exhaust aftertreatment system of claim 19, further comprising: a first differential pressure sensor (228) positioned across the SCR (204) with filter, the first differential pressure sensor (228) being in operative communication with the aftertreatment control unit (216); and a second differential pressure sensor (230) positioned across a portion of the exhaust aftertreatment system that includes a reductant doser (214), the second differential pressure sensor (230) being in operative communication with the aftertreatment control unit; wherein the aftertreatment control unit is further configured: to determine a first differential pressure measurement value via operational communication with the first differential pressure sensor (228), to determine a soot load value based on the first differential pressure measurement, to determine a second differential pressure measurement value via operational communication with the second differential pressure sensor (230) and to determine a soot deposition value based on the second differential pressure measurement.

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