System and method for managing ammonia slip with a heater

Abstract

Systems and methods for controlling and managing ammonia slip are provided. One method includes receiving, by a controller, data regarding operation of an exhaust aftertreatment system; determining, by the controller, a condition exists for ammonia slip based on the data regarding operation of the exhaust aftertreatment system; determining, by the controller, a condition exists for ammonia storage based on the data regarding operation of the exhaust aftertreatment system; and commanding, by the controller, a heater to activate and heat a component of the exhaust aftertreatment system to reduce an amount of storage of ammonia.

Description

[0001] Cross-reference of related applications

[0002] This application claims the benefit and priority of U.S. Application No. 63 / 173,726, filed April 12, 2021, entitled “SYSTEMS AND METHODS FOR MANAGING AMMONIA SLIP WITH A HEATER”, the entire contents of which are incorporated herein by reference and for all purposes. Technical Field

[0003] This disclosure relates to systems and methods for managing ammonia slip in exhaust aftertreatment systems equipped with heaters. Background Technology

[0004] In recent years, emission regulations for internal combustion engines have become more stringent. Environmental concerns have prompted most parts of the world to impose stricter emission requirements on internal combustion engines. Government agencies, such as the U.S. Environmental Protection Agency (EPA), carefully monitor engine emissions and set acceptable emission standards for engines. For example, emissions testing for diesel compression-ignition engines can monitor the release of diesel particulate matter (PM), nitrogen oxides (NOx), nitrous oxide (N2O), ammonia (NH3), hydrocarbons (HC), carbon monoxide (CO), and other emissions to assess these emission characteristics relative to one or more thresholds or emission regulations.

[0005] Traditional exhaust aftertreatment systems include any of several different components to reduce the level of harmful exhaust gas emissions present in the exhaust gases. For example, some 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), and / or an ammonia slip catalyst (ASC) (also known as an ammonia oxidation catalyst (AMOX)). Each of the DOC, SCR catalyst, DPF, and / or ASC components is configured to perform specific exhaust gas treatment operations on the exhaust gases passing through or through the respective component in order to emit relatively fewer environmentally harmful gases into the environment. Summary of the Invention

[0006] Various aspects of this disclosure may be implemented in one or more of the following embodiments:

[0007] Project 1): A method comprising:

[0008] The controller receives data regarding the operation of the exhaust aftertreatment system;

[0009] The controller determines the presence of ammonia slip based on the data regarding the operation of the exhaust aftertreatment system;

[0010] The controller determines the presence of ammonia storage conditions based on the data regarding the operation of the exhaust aftertreatment system; and

[0011] The controller commands the heater to activate and heat the components of the exhaust aftertreatment system to reduce the amount of ammonia stored.

[0012] Project 2): According to the method of Project 1), wherein the condition for ammonia escape is at least one of the following: the system output NOx sensing measurement exceeds the engine output NOx sensing measurement or the ammonia sensing measurement exceeds the ammonia escape threshold.

[0013] Project 3): The method according to Project 1) further includes determining the ammonia storage based on at least one of the following: a sensing measurement of NOx output from the engine, a sensing measurement of NOx output from the system, the feed rate of the diesel exhaust fluid, the exhaust flow rate, or the sensing temperature of the exhaust aftertreatment system.

[0014] The condition for ammonia escape is that the determined ammonia storage amount exceeds the ammonia escape threshold.

[0015] Project 4): According to the method of Project 1), wherein the condition for determining the presence of the ammonia storage is based on the sensing temperature of the selective catalytic reduction (SCR) or the sensing temperature of the ammonia escape catalyst (ASC) being below a threshold, and

[0016] The component heated by the heater is the SCR.

[0017] Project 5): According to the method described in Project 4), wherein the heater is integrated into the SCR.

[0018] Project 6): According to the method described in Project 1), the condition for determining the presence of the ammonia storage is based on the engine fuel supply rate exceeding a transient threshold, and

[0019] The component heated by the heater is the ammonia escape catalyst (ASC).

[0020] Project 7): According to the method described in Project 6), wherein the heater is integrated into the ASC.

[0021] Project 8): A system comprising:

[0022] An exhaust aftertreatment system, comprising a heater; and

[0023] A controller, coupled to the exhaust aftertreatment system, is configured to:

[0024] Receive data regarding the operation of the exhaust aftertreatment system;

[0025] Based on data regarding the operation of the exhaust aftertreatment system, conditions for ammonia escape were determined.

[0026] Based on data regarding the operation of the exhaust aftertreatment system, it was determined that conditions for ammonia storage existed; and

[0027] The heater is commanded to activate and heat the components of the exhaust aftertreatment system to reduce the amount of ammonia stored.

[0028] Project 9): According to the system described in Project 8), the condition for ammonia escape is at least one of the following: the system output NOx sensor measurement exceeds the engine output NOx sensor measurement or the ammonia sensor measurement exceeds the ammonia escape threshold.

[0029] Project 10): The system according to Project 8), wherein the controller is further configured to:

[0030] The ammonia storage level is determined based on at least one of the following: a sensing measurement of NOx output from the engine, a sensing measurement of NOx output from the system, or a sensing temperature from the exhaust aftertreatment system.

[0031] The condition for ammonia escape is that the determined ammonia storage amount exceeds the ammonia escape threshold.

[0032] Item 11): According to the system described in Item 8), the condition for determining the presence of the ammonia storage is based on the sensing temperature of the selective catalytic reduction (SCR) or the sensing temperature of the ammonia escape catalyst (ASC) being below a threshold, and

[0033] The component heated by the heater is the SCR.

[0034] Project 12): According to the system described in Project 11), the controller is further configured to:

[0035] Determine that the current temperature of the SCR is lower than the target temperature of the SCR by a greater than a threshold, and command the heater to activate at a first power level; or

[0036] The current temperature of the SCR is determined to be less than the target temperature of the SCR by a margin of less than the threshold, and the heater is commanded to activate at a second power level less than the first power level.

[0037] Project 13): According to the system described in Project 8), the condition for determining the presence of the ammonia storage is based on the engine fuel supply rate exceeding a predetermined high fuel supply rate threshold for a predetermined time period, and

[0038] The component heated by the heater is the ammonia escape catalyst (ASC).

[0039] Project 14): The system according to Project 13), wherein the heater is integrated into the ASC.

[0040] Item 15): A non-transitory computer-readable storage medium comprising computer-readable instructions stored thereon, which, when executed by a processor of a controller, cause the controller to perform operations including:

[0041] Receive data on the operation of the exhaust aftertreatment system, the data including at least one of the following: (i) a sensing measurement of NOx output from the engine and a sensing measurement of NOx output from the system or (ii) a sensing measurement of ammonia in the exhaust gas stream;

[0042] The conditions for the existence of ammonia slip are determined based on the following: (i) the system output NOx sensing value exceeds the engine output NOx sensing value, or (ii) the ammonia sensing value in the exhaust gas exceeds a threshold; and

[0043] Based on the presence of the ammonia escape condition, the heater is commanded to activate to heat the components of the exhaust aftertreatment system.

[0044] Item 16): The non-transitory computer-readable medium according to Item 15), wherein the operation further includes:

[0045] Receive data regarding the amount of fuel supplied to the engine, which is coupled to the exhaust aftertreatment system; and

[0046] Determining that the amount of fuel supplied to the engine exceeds a predetermined threshold is a prerequisite for commanding the heater to activate.

[0047] Item 17): The non-transitory computer-readable medium according to Item 15), wherein the operation further includes:

[0048] Receive data on the temperature of the components of the exhaust aftertreatment system; and

[0049] The heater is commanded to deactivate if the temperature exceeds a predetermined threshold temperature.

[0050] Item 18): A non-transitory computer-readable medium according to Item 17), wherein the component is an ammonia escape catalyst (ASC).

[0051] Item 19): The non-transitory computer-readable medium according to Item 18), wherein the heater is integrated into the ASC.

[0052] Item 20): The non-transitory computer-readable medium according to Item 15), wherein the operation further includes:

[0053] Determine that the current temperature of the component is lower than the target temperature of the component by a greater than a threshold, and command the heater to activate at a first power level; or

[0054] The current temperature of the component is determined to be less than a threshold value below the target temperature of the component, and the heater is commanded to activate at a second power level less than the first power level.

[0055] One embodiment relates to a method for managing and controlling ammonia slip from an exhaust aftertreatment system. The method includes: receiving data regarding the operation of the exhaust aftertreatment system by a controller; determining, based on the data regarding the operation of the exhaust aftertreatment system, conditions for ammonia slip; determining, based on the data regarding the operation of the exhaust aftertreatment system, conditions for ammonia storage; and commanding a heater to activate and heat components of the exhaust aftertreatment system to reduce the amount of ammonia stored. By reducing the amount of stored ammonia, the method reduces the likelihood of ammonia slip through controlled release of the stored ammonia. Because ammonia release typically peaks as exhaust temperature rises during operation, by reducing the amount of stored ammonia before the rise, the method avoids the peak and reduces the likelihood and / or amount of ammonia slip.

[0056] Another embodiment relates to a system. The system includes an exhaust aftertreatment system and a controller coupled to the exhaust aftertreatment system, the exhaust aftertreatment system including a heater. The controller is configured to: receive data regarding the operation of the exhaust aftertreatment system; determine, based on the data regarding the operation of the exhaust aftertreatment system, that conditions for ammonia escape exist; determine, based on the data regarding the operation of the exhaust aftertreatment system, that conditions for ammonia storage exist; and command the heater to activate and heat components of the exhaust aftertreatment system to reduce the amount of ammonia stored.

[0057] Another embodiment relates to a non-transitory computer-readable storage medium including computer-readable instructions stored thereon, which, when executed by a processor of a controller, cause the controller to perform certain operations. The operations include: receiving data regarding the operation of an exhaust aftertreatment system, the data including at least one of: (i) a sensing measurement of NOx output from the engine and a sensing measurement of NOx output from the system, or (ii) a sensing measurement of ammonia in the exhaust gas stream; determining that a condition for ammonia escape exists based on (i) the sensing measurement of NOx output from the system exceeding the sensing measurement of NOx output from the engine, or (ii) the sensing measurement of ammonia in the exhaust gas stream exceeding a threshold; and commanding a heater to activate to heat components of the exhaust aftertreatment system based on the condition for ammonia escape.

[0058] This overview is illustrative only and is not intended to be limiting in any way. Other aspects, inventive features, and advantages of the apparatus or process described herein will become apparent from the detailed description set forth herein in conjunction with the accompanying drawings, in which like reference numerals refer to like elements. Numerous specific details are provided to give a thorough understanding of embodiments of the subject matter of this disclosure. In one or more embodiments and / or implementations, the features described in this disclosure may be combined in any suitable manner. In this respect, one or more features of one aspect of the invention may be combined with one or more features of different aspects of the invention. Furthermore, additional features that may not be present in all embodiments or implementations may be identified in some embodiments and / or implementations. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of a system with a controller according to an exemplary embodiment.

[0060] Figure 2 This is a schematic diagram of an example architecture of a heater in an exhaust aftertreatment system located upstream of the SCR, integrated with the SCR, and integrated with an ammonia escape catalyst, according to various exemplary embodiments. This architecture can be integrated with... Figure 1 Used together with the system.

[0061] Figure 3 This is according to an exemplary embodiment. Figure 1 A schematic diagram of the system's controller.

[0062] Figure 4 It is a graph depicting experimental values ​​of ammonia release as a function of SCR temperature, according to an exemplary embodiment.

[0063] Figure 5A This is for slowly raising according to an exemplary embodiment. Figure 1 A flowchart of a method for reducing ammonia storage by controlling the temperature of components in the exhaust aftertreatment system, particularly the temperature of the SCR.

[0064] Figure 5B This is for slowly raising according to an exemplary embodiment. Figure 1 A flowchart of a method for reducing ammonia storage by controlling the temperature of components in the exhaust aftertreatment system, particularly the temperature of the SCR.

[0065] Figure 6 It is a set of graphs showing experimental values ​​of speed / torque, fuel supply, aftertreatment system temperature and NOx value relative to time, according to an exemplary embodiment, to indicate instances of ammonia slip over time.

[0066] Figure 7AThis is a flowchart of a method for increasing the temperature of an ammonia slip catalyst (ASC) in an exhaust aftertreatment system to reduce or mitigate ammonia slip, according to an exemplary embodiment.

[0067] Figure 7B This is a flowchart of a method for slowly increasing the temperature of the exhaust gas aftertreatment system (ASC) to reduce or mitigate ammonia slip, according to an exemplary embodiment. Detailed Implementation

[0068] The following is a more detailed description of various concepts and implementations related to methods, apparatus, and systems for managing and controlling ammonia slip from exhaust aftertreatment systems. Before turning to the accompanying drawings, which illustrate certain exemplary embodiments in detail, it should be understood that this disclosure is not limited to the details or methods set forth in the specification or shown in the drawings. It should also be understood that the terminology used herein is for descriptive purposes only and should not be considered limiting.

[0069] Referring generally to the accompanying drawings, the various embodiments disclosed herein relate to systems, apparatus, and methods for managing and controlling ammonia slip from exhaust aftertreatment systems. "Ammonia slip" refers to ammonia that does not react with NOx during the reduction of nitrogen oxides (NOx) but is released into the environment. In operation, ammonia is injected into the exhaust gas stream in the form of a urea solution (or DEF, diesel exhaust fluid) and reacts with NOx in the presence of an exhaust aftertreatment system catalyst (selective catalytic reduction (SCR) catalyst) to form components less harmful to the environment (e.g., water and nitrogen). However, some of the injected ammonia may not be fully utilized in the reaction. This remaining ammonia may accumulate in the aftertreatment system and eventually be released into the atmosphere. This unreacted ammonia released into the environment is called ammonia slip, which can be harmful to the environment, causing undesirable odors and potentially other undesirable effects. Furthermore, one or more fault indicators (e.g., fault codes, malfunction indicator lights, etc.) may be triggered because the tailpipe NOx sensor for OBD (on-board diagnostics) purposes reads NH3 as NOx due to cross-sensitivity. Therefore, it is necessary to manage and control ammonia escape and ammonia accumulation in exhaust aftertreatment systems.

[0070] As described herein, the controller determines the presence of ammonia slip based on data regarding the operation of the exhaust aftertreatment system, determines that the ammonia storage exceeds a threshold, and heats components of the aftertreatment system to reduce the ammonia storage. Specifically, according to one embodiment, the exhaust aftertreatment system is contained within a vehicle and includes a heater that increases the temperature of the exhaust gas flowing through the aftertreatment system or components within the aftertreatment system. Advantageously, this accumulation is reversed when the SCR catalyst heats up, and the ammonia accumulated on the SCR catalyst is released back into the exhaust gas stream. This controlled release of ammonia contributes to the NOx reduction process in the exhaust gas. If the SCR catalyst temperature reaches a spike, a relatively large amount of ammonia is suddenly released. In an exhaust aftertreatment system including an ammonia slip catalyst (ASC), this sudden release of a large amount of ammonia can overwhelm the ASC, leading to ammonia slip. Furthermore, if the ASC itself is not at an appropriate temperature, the ASC cannot convert excess ammonia into, for example, nitrogen and water, which will lead to increased ammonia slip. The systems, apparatus, and methods disclosed herein are operable to effectively manage the release of stored ammonia, thereby reducing ammonia escape from the post-treatment system.

[0071] Now refer to Figure 1 The diagram illustrates a system 100 according to an example embodiment. System 100 includes an engine 110, an aftertreatment system 120, an operator input / output (I / O) device 130, and a controller 140, wherein the controller 140 is communicatively coupled to each of the aforementioned components. Figure 1 In this configuration, system 100 is included in a vehicle. The vehicle can be any type of on-road or off-road vehicle, including but not limited to wheel loaders, forklifts, long-haul trucks, medium-duty trucks (e.g., pickups), sedans, coupes, tanks, aircraft, boats, and any other type of vehicle. In another embodiment, system 100 may be included in stationary equipment, such as a generator or generator set. All these variations are intended to fall within the scope of this disclosure.

[0072] Engine 110 can be any type of engine that produces exhaust gases, such as a gasoline engine, a natural gas engine, a diesel engine, a hybrid engine (e.g., a combination of an internal combustion engine and an electric motor), and / or any other suitable engine. In the described example, engine 110 is a diesel-powered compression-ignition engine.

[0073] The aftertreatment system 120 is in exhaust gas receiving communication with the engine 110. The aftertreatment system includes a diesel particulate filter (DPF) 121, a diesel oxidation catalyst (DOC) 122, a selective catalytic reduction (SCR) system 123, an ammonia slip catalyst (ASC) 124, and a heater 125. The DOC 122 is configured to receive exhaust gas from the engine 110 and oxidize hydrocarbons and carbon monoxide in the exhaust gas. The DPF 121 is arranged or positioned downstream of the DOC 122 and is configured to remove particulate matter, such as soot, from the exhaust gas flowing in the exhaust gas stream. The DPF 121 includes an inlet and an outlet, receiving exhaust gas at the inlet and discharging exhaust gas at the outlet after substantially filtering out particulate matter and / or converting particulate matter into carbon dioxide. In some embodiments, the DPF 121 or other components may be omitted. Furthermore, although in Figure 1 The diagram shows a specific arrangement for the post-processing system 120, but in other embodiments, the arrangement of components within the post-processing system 120 may be different (e.g., DPF 121 is located downstream of SCR 123 and AMOX 124, one or more components are omitted or added, etc.).

[0074] The aftertreatment system 120 may also include a reducing agent delivery system, which may include a decomposition chamber (e.g., a decomposition reactor, reactor pipe, decomposition tube, reactor tube, etc.) to convert the reducing agent into ammonia. The reducing agent may be, for example, urea or diesel exhaust fluid (DEF). Urea water solution (UWS), aqueous urea solution (e.g., AUS32), and other similar fluids are used. Diesel exhaust fluid (DEF) is added to the exhaust gas stream to aid catalytic reduction. The reducing agent is typically injected upstream of the SCR 123 (usually or particularly the SCR catalyst) via a DEF feeder, allowing the SCR catalyst to receive the mixture of reducing agent and exhaust gas. The reducing agent droplets then undergo evaporation, pyrolysis, and hydrolysis to form gaseous ammonia within the decomposition chamber, SCR catalyst, and / or exhaust duct system, exiting the aftertreatment system 120. The aftertreatment system 120 may also include an oxidation catalyst (e.g., DOC 122), fluidly coupled to the exhaust duct system to oxidize hydrocarbons and carbon monoxide in the exhaust gas. To properly aid this reduction, the DOC 122 may need to be at a specific operating temperature. In some embodiments, this specific operating temperature is approximately between 200°C and 500°C. In other embodiments, a specific operating temperature is the temperature at which the conversion efficiency of DOC122 exceeds a predetermined threshold (e.g., the conversion of HC to a less harmful compound, referred to as HC conversion efficiency).

[0075] SCR 123 is configured to help reduce NOx emissions by accelerating the NOx reduction process between NOx and ammonia in exhaust gas, converting it into nitrogen and water. If the SCR catalyst is not at or above a specific temperature, the acceleration of the NOx reduction process is limited, and SCR 123 may not be able to operate at the specified efficiency level. In some embodiments, this specific temperature is approximately 200°C–600°C. The SCR catalyst can be made from a combination of inactive materials and an active catalyst, such that the inactive material (e.g., a ceramic substrate) directs the exhaust gas to the active catalyst, which is any kind of material suitable for catalytic reduction (e.g., metal-exchanged zeolites (Fe or Cu / zeolite), base metal oxides (e.g., vanadium, molybdenum, tungsten, etc.)).

[0076] When ammonia in the exhaust gas does not react with the SCR catalyst (either because SCR 123 is below operating temperature or because the amount of ammonia added greatly exceeds the amount of NOx), unreacted ammonia can bind to the SCR catalyst and be stored in SCR 123. When SCR 123 warms up, this stored ammonia is released from SCR 123, which can cause problems if the amount of ammonia released is greater than the amount of NOx passing through (i.e., more ammonia than the amount of NOx required, which may lead to ammonia slip). In some embodiments, ASC 124 is included and configured to address ammonia slip by removing at least some of the excess ammonia from the treated exhaust gas before it is released into the atmosphere. As the exhaust gas passes through ASC 124, some of the unreacted ammonia remaining in the exhaust gas (i.e., ammonia that has not reacted with NOx) is partially oxidized to NOx, which then reacts with the remaining unreacted ammonia to form N2 gas and water. However, similar to SCR catalysts, the acceleration of the NH3 oxidation process is limited if the ASC 124 is not at or above a certain temperature, and the ASC 124 may not be able to operate at the efficiency level required to meet specified or desired parameters. In some embodiments, this specific temperature is approximately 250°C–300°C.

[0077] Due to the problems associated with excessive ammonia storage, it is desirable to reduce the total amount of ammonia stored in the SCR 123 and the exhaust aftertreatment system. Furthermore, reducing ammonia storage before transient events occur is particularly important. A transient event is a period of time during which the current power demand on engine 110 differs significantly from the previous power demand (e.g., exceeding a threshold delta amount, such as a 25% increase in power output). For example, when overtaking another vehicle on a highway, the vehicle operator may depress the accelerator pedal as far or almost as far as possible before returning to the previous steady-state position. This instant is a transient event. As another example, when a vehicle is traveling uphill after a substantially non-slope crossing, this uphill travel may be a transient event. Although described above regarding vehicle speed, transient moments / events can also be defined with respect to engine speed or torque or the operation of other vehicle components (e.g., spikes in exhaust aftertreatment system temperature, etc.). For example, in other embodiments, an aftertreatment sensor (e.g., NOx) can be used to determine characteristics of the aftertreatment system (e.g., engine output NOx), and if that value exceeds a predetermined threshold, a transient event is identified (e.g., an increase in the amount of engine output NOx relative to the current amount of engine output NOx exceeding a predetermined threshold can indicate a transient event or moment). In other words, transient events can be determined based on the operating characteristics of the aftertreatment system (e.g., engine output NOx, system output NOx, etc.).

[0078] During transient events, the aftertreatment system 120 frequently experiences rapid temperature changes (e.g., temperature increases in response to increased load or power output). Specifically, the temperature increase is caused by an increase in power demand on engine 110. This situation results in an increase in engine exhaust gas temperature. As previously mentioned, when the SCR 123 heats up rapidly (e.g., the rate of temperature increase exceeds a threshold), substantially all or at least a large amount of ammonia stored in the SCR catalyst is released through this rapid heating, while the insufficiently heated ASC 124 cannot oxidize the higher amount of ammonia released during the transient event. This can lead to unacceptable levels of ammonia slip. Therefore, it is desirable to reduce the amount of ammonia stored in the SCR 123 before the transient event. Furthermore, the less ammonia stored in the SCR 123, the hotter the SCR 123 must be before ammonia release begins. Therefore, reducing the amount of ammonia stored in SCR123 increases the likelihood that ASC 124 will be at its operating temperature, also known as the light-off temperature, which refers to the temperature or temperature range at which ASC 124 oxidizes ammonia at the desired rate.

[0079] Still referencing Figure 1 The heater 125 is located in the exhaust flow path preceding the aftertreatment system 120 and is configured to controllably heat the exhaust gas upstream of the aftertreatment system 120. In some embodiments, the heater 125 is located directly preceding the SCR 123. In other embodiments, the heater 125 is directly integrated into components of the aftertreatment system (e.g., SCR 123, ASC 124) to form an electro-heated catalytic converter (EHC). Figure 2 An example architecture of a heater 125 within a post-processing system 120 according to various exemplary embodiments is shown. Figure 2 As shown, the first architecture 210 shows the heater 125 downstream of the engine 110 but upstream of both the SCR 123 and ASC 124. The second architecture 220 shows the heater 125 downstream of the engine 110 and upstream of the ASC 124, but directly integrated into the SCR 123 (forming an EHC). The third architecture 230 shows the heater 125 downstream of both the engine 110 and the SCR 123, but directly integrated into the ASC 124 (forming an EHC).

[0080] Heater 125 can be any type of heat source configured to raise the temperature of the passing exhaust gas, which in turn raises the temperature of components in aftertreatment system 120, such as DOC 122 or SCR 123. Therefore, heater 125 can directly heat the exhaust gas and / or heat components (e.g., SCR) to indirectly heat the exhaust gas (or directly raise the temperature of those components, e.g., the SCR catalyst). Thus, the heater can be an electric heater (e.g., an induction heater or a microwave heater) or a fuel combustion (e.g., HC fuel) heater. As shown here, heater 125 is an electric heater that draws power from the battery of system 100. In other embodiments, different power sources can power the heater (e.g., gaseous or liquid fuel, battery, or other power sources integrated with the heater, etc.). Heater 125 can be controlled by controller 140. For example, heater 125 can be controlled during an active regeneration event to heat the exhaust gas (e.g., by convection). Alternatively, the heater can be positioned near desired components to heat components (e.g., DOC or DPF) by conduction (and possibly convection). Multiple heaters can be used with the exhaust aftertreatment system, and each heater can have the same or different construction (e.g., conduction, convection, etc.).

[0081] Still referencing Figure 1 Operator input / output (I / O) device 130 is also shown. Operator I / O device 130 can be communicatively coupled to controller 140, enabling the exchange of information between controller 140 and I / O device 130, wherein this information may relate to… Figure 1 The determination of one or more components or controllers 140 (described below). Operator I / O device 130 enables the vehicle operator to communicate with... Figure 1 The controller 140 communicates with one or more components of the vehicle. For example, the operator input / output device 130 may include, but is not limited to, an interactive display, a touch screen device, one or more buttons and switches, a voice command receiver, etc.

[0082] Brief Reference Figure 3As also shown in the figure, sensor array 129 is included in post-treatment system 120. The sensors are coupled to controller 140, enabling controller 140 to monitor and acquire data indicative of operation of system 100. In this regard, the sensor array includes NOx sensor 128 and temperature sensor 127. NOx sensor 128 acquires data indicating the amount of NOx at or approximately at its location, or determines the amount of NOx if dummy. Temperature sensor 127 acquires data indicating the approximate temperature of the exhaust gas at or approximately at its location, or determines the approximate temperature if dummy. It should be understood that the location, number, and type of sensors described are merely illustrative. In other embodiments, sensors may be located in other locations, there may be more or fewer sensors than shown, and / or different / additional sensors may also be included in system 100 (e.g., pressure sensors, ammonia sensors, flow rate sensors, etc.). Those skilled in the art will understand and recognize the high configurability of the sensors in system 100.

[0083] Controller 140 is configured to at least partially control the operation of system 100 and associated subsystems (e.g., engine 110 and operator input / output (I / O) devices 130). Communication between and within components can be via any number of wired or wireless connections. For example, wired connections may include serial cables, fiber optic cables, CAT5 cables, or any other form of wired connection. In contrast, wireless connections may include the Internet, Wi-Fi, cellular, radio, etc. In one embodiment, a controller local 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 controller 140 is communicatively coupled to... Figure 1 The system and components, so the controller 140 is configured to... Figure 1 One or more components are shown receiving data. (Refer to...) Figure 3 The structure and function of controller 140 are further described.

[0084] because Figure 1 The component is shown as being included in system 100 within a vehicle, and controller 140 may be configured as one or more electronic control units (ECUs). Figure 3The function and structure of controller 140 are described in more detail below. Controller 140 may be separate from or included within at least one of a transmission control unit, exhaust aftertreatment control unit, powertrain control module, engine control module, etc. In one embodiment, the components of controller 140 are combined into a single unit. In another embodiment, one or more components may be geographically distributed throughout the system or vehicle. All these variations are intended to fall within the scope of this disclosure. Controller 140 may be configured as one or more electronic control units (ECUs). Figure 3 The function and structure of controller 140 are described in more detail.

[0085] Now for reference Figure 3 According to the example embodiment, Figure 1 A schematic diagram of the controller 140 of system 100. (See diagram below.) Figure 3 As shown, controller 140 includes processing circuitry 302 with processor 304 and memory 306, SCR circuitry 320, ASC circuitry 322, and communication interface 310. Controller 140 is configured or constructed to determine whether conditions are present that indicate a high probability of ammonia slip and to command heater 125 to engage and heat components of the aftertreatment system in order to preemptively address the potential for ammonia slip.

[0086] In one configuration, SCR circuitry 320 and ASC circuitry 322 are implemented as a machine- or computer-readable medium storing instructions executable by a processor such as processor 304. As described herein and in other uses, the machine-readable medium facilitates the performance of certain operations to achieve the reception and transmission of data. For example, the machine-readable medium can provide instructions (e.g., commands, etc.) to, for example, acquire data. In this regard, the machine-readable medium may include programmable logic defining the frequency of data acquisition (or data transmission). The computer-readable medium instructions may include code that can be written in any programming language, including but not limited to Java and any conventional procedural programming language, such as the "C" programming language or similar programming languages. The computer-readable program code can be executed on one processor or multiple remote processors. In the latter case, the remote processors can be interconnected via any type of network (e.g., CAN bus, etc.).

[0087] In another configuration, SCR circuit 320 and ASC circuit 322 are implemented as hardware units, such as electronic control units. Therefore, SCR circuit 320 and ASC circuit 322 can be implemented as one or more circuit components, including but not limited to processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc. In some embodiments, SCR circuit 320 and ASC circuit 322 can take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (ICs), discrete circuits, system-on-a-chip (SoC) circuits, microcontrollers, etc.), telecommunications circuits, hybrid circuits, and any other type of "circuit". In this respect, SCR circuit 320 and ASC circuit 322 can include any type of component for performing or facilitating the implementation of the operations described herein. For example, the circuits described herein can include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, etc. SCR circuit 320 and ASC circuit 322 may also include programmable hardware devices, such as field-programmable gate arrays, programmable array logic, programmable logic devices, etc. SCR circuit 320 and ASC circuit 322 may include one or more memory devices for storing instructions executable by the processor of SCR circuit 320 and ASC circuit 322. The one or more memory devices and processor may have the same definitions as provided below regarding memory 306 and processor 304. In some hardware unit configurations, SCR circuit 320 and ASC circuit 322 may be geographically distributed across various individual locations within the system and / or vehicle. Optionally, as shown, SCR circuit 320 and ASC circuit 322 may be contained within or within a single unit / housing, shown as controller 140.

[0088] In the example shown, controller 140 includes processing circuitry 302 having processor 304 and memory 306. Processing circuitry 302 may be constructed or configured to execute or implement the instructions, commands, and / or control processes described herein with respect to SCR circuitry 320 and ASC circuitry 322. The depicted configuration represents SCR circuitry 320 and ASC circuitry 322 as a machine or computer-readable medium storing instructions. However, as noted above, this illustration is not intended to be limiting, as other embodiments are contemplated in this disclosure, wherein SCR circuitry 320 and ASC circuitry 322, or at least one of SCR circuitry 320 and ASC circuitry 322, are configured as hardware units. All such combinations and variations are intended to fall within the scope of this disclosure.

[0089] Processor 304 may be implemented as a single-chip processor or multi-chip processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The processor may be a microprocessor. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some embodiments, one or more processors may be shared by multiple circuits (e.g., SCR circuit 320 and ASC circuit 322 may include or otherwise share the same processor, which in some example embodiments may execute instructions stored or otherwise accessed via different regions of memory). Alternatively or additionally, one or more processors may be configured to implement or otherwise perform certain operations independently of one or more coprocessors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multithreaded instruction execution. All these variations are intended to fall within the scope of this disclosure.

[0090] Memory 306 (e.g., memory, memory cell, storage device) may include one or more devices (e.g., RAM, ROM, flash memory, hard disk storage) for storing data and / or computer code to perform or facilitate the various processes, layers, and modules described herein. Memory 306 may be communicatively connected to processor 304 to provide processor 304 with computer code or instructions for performing at least some of the processes described herein. Furthermore, memory 306 may be or may include tangible, non-transient volatile memory or non-volatile memory. Therefore, memory 306 may include database components, object code components, scripting components, or any other type of information structure for supporting the various activities and information structures described herein.

[0091] SCR circuit 320 is constructed or configured to determine the possibility of ammonia slip and, in response, slowly heats SCR 123 to reduce the rate at which ammonia stored in SCR 123 is released into the exhaust gas stream. "Possibility of ammonia slip" or "ammonia slip conditions" refers to the conditions of aftertreatment system 120 associated with the possibility of ammonia slip. When the entire aftertreatment system 120 is at a low temperature and up to a higher temperature (e.g., approximately 250°C), ammonia released from SCR 123 may cause ammonia slip because ASC 124 is not ignited (the operating temperature / characteristic for actively oxidizing excess ammonia at the desired rate has not been reached). However, if the amount of ammonia stored in SCR 123 is relatively small (i.e., a low level of ammonia storage), ammonia will not begin to be released from SCR 123 until a higher overall aftertreatment system 120 temperature, at which point ASC 124 is more likely to have reached its ignition temperature (i.e., the temperature at which ammonia is oxidized at the desired rate). Therefore, when ammonia does begin to be released from SCR 123, ASC 124 is prepared to actively oxidize the released ammonia, thereby reducing the likelihood and / or amount of ammonia escape.

[0092] Figure 4 This is a graph 400 illustrating experimental values ​​of ammonia release as a function of SCR 123 temperature, according to an exemplary embodiment. The x-axis of graph 400 reflects the temperature of the SCR 123 and is given in degrees Celsius (°C), with values ​​increasing from left to right. The y-axis of graph 400 reflects the amount of ammonia released from storage and is given in parts per million (ppm), with values ​​increasing from bottom to top. Line 410 plots the amount of ammonia released from a fully saturated (i.e., fully ammonia-storage) SCR 123. Line 420 plots the amount of ammonia released from a partially saturated (i.e., partially ammonia-storage) SCR 123 under inert conditions (e.g., exhaust gas is substantially oxygen-free). Line 430 plots the amount of ammonia released from a partially saturated SCR 123 under oxidizing conditions (e.g., exhaust gas contains 10% O2). Comparing lines 420 and 430 shows that no NH3 oxidation occurs in the SCR catalyst below 350°C; in other words, the NH3 released below 350°C will reach AMOX. Clearly, when SCR 123 is less saturated (as in lines 420 and 430), ammonia is released in large quantities only when SCR 123 is much hotter, whereas for a fully saturated SCR 123, ammonia is released even at low temperatures.

[0093] In one embodiment where the sensor array includes a NOx sensor 128 but not an NH3 sensor, the SCR circuit 320 determines the likelihood of ammonia slip based on a sensing amount where the system output NOx (SONOx) is greater than the sensing amount where the engine output NOx (EONOx) exceeds a predetermined threshold amount. In some embodiments, these sensing amounts come from one or more real sensors located throughout the system 100 (e.g., at the outlet of engine 110, at the outlet of aftertreatment system 120, etc.). In another embodiment, one or more of the SONOx and EONOx sensors are virtual sensors that determine or estimate based on system operating conditions (e.g., a virtual SONOx sensor estimates the system output NOx as a value X under various engine power requirements and operating characteristics). Each of the real sensor embodiments and the virtual sensor embodiments is intended to fall within the scope of this disclosure.

[0094] As described above, the SCR circuit 320 is configured or constructed to determine the possibility of ammonia escape when the SONOx amount or value is greater than the EONOx amount or value. Because excess ammonia can be read as NOx by the tailpipe sensor, and because NOx may only be produced by the engine 110, the EONOx amount or value exceeding the SONOx value can be attributed to unreacted ammonia in the exhaust gas stream. The NOx sensor is typically “cross-sensitive” (i.e., reads NH3 as NOx) because it operates at high temperatures (e.g., >200°C), and due to the high temperature, NH3 is oxidized to NOx within the sensor, causing the NOx sensor to read NH3 as NOx. Typically, this cross-sensitivity is approximately 0.9–1, meaning that 100 ppm of NH3 is read as 90–100 ppm of NOx by the NOx sensor. Therefore, unless there is a fault in system 100 due to a low probability of additional NOx generation between the engine output sensor and the system output sensor (which can be demonstrated by the activation of one or more fault codes), the SCR circuit 320 determines that the increase in NOx sensed between the engine output sensor and the system output sensor is due to the system output sensor reading ammonia in the exhaust gas as NOx. In this way, the applicant has determined that the excessive NOx reading between the SONOx sensor and the EONOx sensor is due to the presence of ammonia. The SCR circuit 320 determines that this excess is ammonia slip. This determined ammonia slip can be compared with an ammonia slip threshold and the operating temperature to determine whether ammonia slip is likely (i.e., if the determined ammonia slip exceeds the threshold, the SCR circuit determines that ammonia slip is possible). In other words, when the SONOx sensing value exceeds the EONOx sensing value exceeding a predetermined threshold, the SCR circuit 320 determines that there is a possibility (i.e., a high probability) that ammonia slip is occurring or will occur.

[0095] When the system does not include an ammonia sensor (i.e., a direct reading of the amount, storage capacity, or instantaneous quantity of ammonia), it is impossible to determine the possibility of ammonia escape that can be used by the SCR circuit 320.

[0096] In another embodiment where the sensor array 129 includes an NH3 sensor, the SCR circuit 320 determines the likelihood of ammonia escape based on the amount of ammonia sensed in the exhaust gas exceeding an escape threshold (e.g., 500 ppm, 80% saturation level, etc.). The NH3 sensor in this embodiment can be embedded in the SCR 123 or ASC 124, located downstream of the aftertreatment system 120 (i.e., a tailpipe sensor), or it can be an NH3 radio frequency (RF) sensor.

[0097] In another embodiment of system 100 that does not include an NH3 sensor, the NH3 saturation level (or ammonia storage level) may also be determined via a virtual sensor that utilizes one or more of the following: data from the engine output NOx sensor, data from the tailpipe NOx sensor, DEF feed rate, estimated exhaust flow rate, and data from temperature sensor 127. This data is processed by an embedded model running on controller 140. Similar to the embodiment where sensor array 129 includes an NH3 sensor, if controller 140 determines that the predicted NH3 saturation level is above a certain threshold, SCR circuit 320 determines that there is a potential risk of NH3 escape.

[0098] In response to the SCR circuit 320 determining the possibility of ammonia escape, the SCR circuit 320 determines the state of ammonia storage in one or more of the aftertreatment systems 120 under various conditions or locations. Specifically, the SCR circuit 320 determines the state of ammonia storage based on the temperature of one or more components in the aftertreatment system 120.

[0099] In a first embodiment, the SCR circuit 320 determines the ammonia storage based on the temperature of the SCR 123. If the temperature of the SCR 123 is below a predetermined threshold (e.g., 250°C, ignition temperature, etc.), the SCR circuit 320 determines that there may be an unacceptable amount of ammonia stored in the SCR because ammonia storage is higher at lower temperatures. In some embodiments, the SCR circuit 320 determines that the SCR 123 temperature is below the threshold momentarily (i.e., at a certain moment), while in other embodiments, the SCR circuit 320 determines that the SCR 123 temperature is below the threshold if the SCR 123 temperature remains below the threshold for a certain period of time (e.g., 30 seconds). For example, if the system operates for X seconds or X minutes with DEF feed and the SCR 123 is below the threshold temperature during this period, the SCR circuit 320 determines that the ammonia stored in the SCR is above the threshold level. This increased ammonia storage at lower temperatures is due to the accumulation of unreacted NH3 over time. Once the temperature rises (i.e., through operation), the stored ammonia is released into the exhaust gas stream. Therefore, a lower SCR 123 temperature indicates a higher ammonia storage on SCR 123.

[0100] In the second embodiment, the SCR circuit 320 makes this determination based on the temperature of the Ascendant 124 (ASC 124). If the temperature of the ASC 124 is below a predetermined threshold (e.g., 250°C, ignition temperature, etc.), the SCR circuit 320 determines that the ASC 124 may not be able to properly oxidize excess ammonia in the exhaust gas stream. In some embodiments, the SCR circuit 320 determines that the ASC 124 temperature is below the threshold momentarily (i.e., at a certain moment), while in other embodiments, the SCR circuit 320 determines that the ASC 124 temperature is below the threshold if the ASC 124 temperature remains below the threshold for a certain period of time (e.g., 30 seconds). Therefore, when the ASC 124 temperature is below the predetermined threshold temperature, unreacted ammonia remaining in the exhaust gas stream may escape into the atmosphere at unacceptable levels. Therefore, if the temperature of SCR 123 or ASC 124 is below a predetermined threshold, SCR circuit 320 can determine that conditions of high ammonia storage exist in post-treatment system 120 (e.g., the amount of stored ammonia exceeds a threshold above which, if released, post-treatment system 120 cannot convert substantially all of the stored ammonia). In an alternative embodiment, SCR circuit 320 determines the presence of high ammonia storage if the temperatures of both SCR 123 and ASC are below the predetermined threshold. It is advantageous to determine the likelihood of ammonia slip and significant ammonia storage by tracking the temperatures of at least SCR 123 and ASC 124 because an NH3 sensor is not required, allowing for adequate ammonia slip detection in systems lacking an NH3 sensor or operating under NH3 sensor failure conditions.

[0101] In response to SCR circuit 320 determining that the ammonia storage state in post-treatment system 120 is unacceptable (i.e., the amount of stored ammonia exceeds a threshold desired amount), SCR circuit 320 engages, activates, and increases the temperature / power of heater 125, etc., to slowly heat (e.g., less than 30°C / min) SCR 123. The heater may be located in the exhaust gas stream upstream of SCR 123 (as shown in first architecture 210) or integrated into SCR 123 (as shown in second architecture 220). By slowly heating SCR 123, SCR circuit 320 causes SCR 123 to slowly release the stored ammonia, which reduces the likelihood of ammonia escape by reducing the amount of ammonia that ASC 124 must oxidize before ASC 124 has time to reach the desired operating temperature (ignition temperature range or threshold). In some embodiments, SCR circuit 320 may simultaneously reduce DEF feed. Then, based on the fact that the SCR 123 is above a predetermined threshold temperature (e.g., 300°C) or if the operating characteristics of the SCR 123 are above a predetermined threshold (e.g., the conversion efficiency of the SCR 123 is above 99%), the SCR circuit 320 is deactivated, the temperature / power of the heater 125 is reduced, etc.

[0102] Now for reference Figure 5AAccording to an exemplary embodiment, a flowchart of a first method 500 for slowly increasing the temperature of SCR 123 to reduce ammonia storage is shown, using SCR circuit 320 and controller 140. In process 510, controller 140 determines the possibility of ammonia escape based on a sensing amount of system output NOx (SONOx) exceeding a sensing amount of engine output NOx (EONOx) exceeding a threshold amount (510: Yes). In process 520, controller 140 determines whether the temperature of SCR 123 or ASC 124 is below a predetermined threshold. If not, method 500 returns to process 510 (520: No) to continue checking the SONOx and EONOx values. If yes, method 500 proceeds to process 530 (520: Yes), where controller 140 commands heater 125 to engage (i.e., activate, turn on, increase temperature power) and slowly heat SCR 123. In some embodiments, “slow heating” refers to a flat rate of temperature increase of the SCR 123 (e.g., 30°C / min), while in other embodiments, the rate at which the heater 125 “slowly heats” the SCR 123 is based on the current temperature of the SCR 123 relative to a target SCR 123 temperature (e.g., “ignition” temperature). In these embodiments, the greater the difference between the current temperature and the target temperature, the greater the rate at which the heater 125 heats the SCR 123 (i.e., the heater 125 is activated at full power, rather than operating at reduced power). Furthermore, this determination may include a comparison with a threshold such that if the difference between the current temperature and the target temperature exceeds the threshold, the heater 125 is fully engaged (i.e., “on” at full power), and if the difference is less than the threshold, the heater 125 is partially engaged (i.e., “on” at less than full power).

[0103] In some embodiments, method 500 continues to process 535, where controller 140 commands the DEF feeder to reduce the feed level. From process 530 or process 535, method 500 proceeds to process 540, where controller 140 determines whether the temperature of SCR 123 exceeds a threshold (i.e., whether SCR 123 has reached its operating temperature). If the temperature of SCR 123 has not yet reached the threshold, the method returns to process 530 (540: No) to continue heater 125 engagement. If the temperature of SCR 123 exceeds the threshold, method 500 continues to process 545, where controller 140 commands heater 125 to disengage.

[0104] Now for reference Figure 5BAccording to an exemplary embodiment, a flowchart of a second method 550 for slowly increasing the temperature of SCR 123 to reduce ammonia storage is shown. In process 560, controller 140 determines the possibility of ammonia escape based on the amount of ammonia sensed (or predicted) in the exhaust gas flow exceeding a threshold. If yes, method 550 proceeds to process 570 (560: yes), where controller 140 determines whether the temperature of SCR 123 or ASC 124 is below a predetermined threshold. If no, method 550 returns to process 560 (570: no) to continue checking for ammonia in the exhaust gas flow. If yes, method 550 proceeds to process 580 (570: yes), where controller 140 commands heater 125 to engage and slowly heat SCR 123, where “slow heating” is defined above. In some embodiments, method 550 continues to process 585, where controller 140 commands DEF feeder to reduce feed level. From process 580 or 585, method 550 proceeds to process 590, where controller 140 determines whether the temperature of SCR 123 exceeds a threshold (i.e., whether SCR 123 has reached its operating temperature). If the temperature of SCR 123 has not yet reached the threshold, the method returns to process 580 (590: No) to continue heater 125 engagement (e.g., keeping heater 125 on, maintaining temperature / power settings on heater 125, etc.). If the temperature of SCR 123 exceeds the threshold, method 550 proceeds to process 595, where controller 140 commands heater 125 to disengage.

[0105] It should be understood that, as part of the "slow heating" process, heater 125 can be activated with different power outputs throughout the process. Therefore, a constant power output can be used in some cases, while a power output that varies over time can be used in others.

[0106] ASC circuit 322 is configured or constructed to determine the possibility of ammonia slip and, in response, heats ASC 124 to prepare ASC 124 for oxidizing ammonia. As described above, the reaction between ASC 124 and ammonia in the exhaust gas stream is more efficient at higher temperatures (e.g., 250°C). At lower temperatures, ASC 124 may not oxidize ammonia with the desired efficiency, which could result in unacceptable levels of ammonia slip. By heating ASC 124 under predicted ammonia slip conditions, ASC circuit 322 reduces the amount and / or likelihood of ammonia slip.

[0107] In one embodiment where the sensor array includes a NOx sensor 128 but not an NH3 sensor, the ASC circuit 322 determines the likelihood of ammonia escape based on the sensing value of system output NOx (SONOx) being greater than the sensing value of engine output NOx (EONOx). Because excess ammonia can be read as NOx by the tailpipe sensor, and because NOx is only produced by the engine 110, any amount by which the EONOx sensing value exceeds the SONOx sensing value can be attributed to unreacted ammonia in the exhaust gas flow, due to the low probability of additional NOx being generated between the engine output sensor and the system output sensor. Therefore, when the SONOx sensing value exceeds the EONOx sensing value by a predetermined threshold, the SCR circuit 320 determines the likelihood (i.e., high probability) that ammonia escape is occurring or will occur. In another embodiment where the sensor array 129 includes an NH3 sensor, the ASC circuit 322 determines the likelihood of ammonia escape based on the amount of ammonia sensed in the exhaust gas flow exceeding an escape threshold (e.g., 500 ppm, 80% saturation level, etc.). In this embodiment, the NH3 sensor can be embedded in the SCR 123 or ASC 124, and can be located downstream of the aftertreatment system 120 (i.e., the tailpipe sensor), or it can be an NH3 radio frequency (RF) sensor. Optionally, the determination of the ammonia escape probability can be performed by the SCR circuit and provided to the ASC circuit 322. This arrangement can help reduce redundant calculations, thereby saving processing power and providing faster determination, for example.

[0108] In response to the ASC circuit 322 determining the possibility of ammonia slip, the ASC circuit 322 determines whether a transient event is occurring or is likely to occur. In one embodiment, the ASC circuit 322 determines that a transient event is occurring or is likely to occur based on the engine's fuel supply rate exceeding a predetermined high fuel supply rate threshold for a period of time. For example, if the fuel supply rate exceeds 250 mg / stroke for 30 seconds, the ASC circuit 322 determines that a transient event is occurring. Alternatively or additionally, the ASC circuit 322 may determine that a transient event is occurring or is likely to occur based on the modeling temperature of the aftertreatment system 120, based on various conditions of the system 100 (e.g., predicting upcoming load conditions of the system based on previous levels of the system 100 to determine the modeling temperature of the aftertreatment system 120). For example, the ASC circuit 322 may predict or determine the temperature of the aftertreatment system 120 based on system 100 operating parameters (e.g., fuel supply rate, power demand, EONOx). If the predicted temperature of the aftertreatment system 120 exceeds a predetermined threshold (or the difference between the current temperature and the predicted temperature rise exceeds a predetermined increment), the ASC circuit 322 determines that a transient event is occurring. During a transient event, the engine output exhaust temperature may rise due to an increase in fuel supply levels, and the hot exhaust gas heats the aftertreatment system 120. As the aftertreatment system 120 heats up, the SCR 123 begins to release stored ammonia, which can lead to ammonia escape if the ASC 124 is not hot enough (i.e., below the threshold temperature (e.g., 250°C)). Specifically, according to one embodiment, when the SCR operates at or below the threshold temperature (250°C) for a relatively long period, where the catalyst maintains a large amount of stored NH3, and then the SCR experiences a sudden temperature ramp to an elevated temperature (e.g., 300°C), the ASC circuit 322 determines that a transient cycle or event is occurring. This situation can result in significant NH3 escape (greater than 400 ppm).

[0109] Therefore, if ASC circuit 322 determines that a transient event is occurring, it commands heater 125 to directly begin heating ASC 124. Here, as shown in third architecture 230, heater 125 is integrated into ASC 124, thus directly heating ASC 124. By focusing on direct heating of ASC 124 (as opposed to indirect heating via hot exhaust gas or an upstream heater), ASC circuit 322 can heat ASC 124 to its ignition temperature (i.e., the desired or preferred operating temperature) more quickly. Experimental data show that when directly targeted by heater 125, the time required for ASC 124 to ignite is approximately equal to the time required for SCR 123 to reach its operating temperature (and begin releasing large amounts of ammonia) from the start of a high fuel supply transient event.

[0110] Figure 6This is a set of graphs 600, according to an exemplary embodiment, showing experimental values ​​of speed / torque, fuel supply, aftertreatment system temperature, and NOx sensor signals relative to time, to indicate instances of ammonia slip over time. According to an exemplary embodiment, these experimental values ​​include fuel supply level as a function of time, aftertreatment system 120 temperature as a function of time, and ASC 124 temperature as a function of time. Figure 6 As shown, the x-axis of each of graphs 610, 620, 630, and 640 reflects the duration of system 100 operation and is given in time units. Each of curves 610, 620, 630, and 640 is aligned relative to the x-axis so that each graph can be read from top to bottom. The y-axis of graph 610 reflects the numerical values ​​of each parameter in different units and includes lines 611, 612, 613, and 614. Line 611 plots the experimental value of engine 110 torque over time (given in Newton-meters), line 612 plots the experimental value of vehicle speed over time (given in km / h*10), line 613 plots the experimental value of exhaust mass flow rate over time (given in kg / min), and line 614 plots the experimental value of engine speed over time (given in revolutions per minute). Generally, lines 611, 612, 613, and 614 reflect values ​​for normal operation of system 100. The y-axis of Chart 620 reflects the engine fuel supply rate, given in milligrams per stroke, and includes line 621. Line 621 plots the experimental value of the total fuel supply level entering engine 110 over time. The y-axis of Chart 630 reflects temperature, given in degrees Celsius. Chart 630 includes lines 631, 632, and 633, each plotting experimental values ​​of temperature within aftertreatment system 120. Line 631 plots the experimental value of SCR 123 outlet temperature, line 632 plots the experimental value of DPF 121 outlet temperature, and line 633 plots the experimental value of SCR 123 inlet temperature. The y-axis of Chart 640 reflects the sensed NOx reading in the exhaust gas at the outlet (i.e., tailpipe) of aftertreatment system 120, given in ppm (%). Chart 640 includes line 641, which plots the experimental SONOx reading in system 100 excluding the NH3 sensor.

[0111] like Figure 6As shown, a relative spike in the fuel supply level directly leads to a relative spike in the temperature of the aftertreatment system 120, which in turn leads to a relative spike in the sensed SONOx. Because excess ammonia can be read as NOx by the tailpipe sensor, a spike in sensed SONOx indicates possible ammonia slip when the tailpipe sensor senses a spike in NOx without a corresponding high NOx event (e.g., high exhaust temperature due to a leaner air / fuel ratio). Referring to graph 620, circles 651 and 652 identify two relative spikes in the fuel supply level. As indicated by the arrows, these relative spikes are followed by relative spikes in the temperature of the aftertreatment system 120 components, identified by circles 661 and 662 on graph 630. Furthermore, these relative spikes in the temperature of the aftertreatment system 120 components lead to relative spikes in the sensed SONOx, as indicated by circles 671 and 672 on graph 640. Due to the nature of the system without an NH3 sensor, an increase in SONOx may indicate an increase in unreacted ammonia in the exhaust gas stream (i.e., ammonia slip). Therefore, the applicant has determined that an increase in the fuel supply level directly leads to an increase in ammonia slip, supported by the experimental data shown in the figures below. Based on this experimental data, the ASC circuit 322 then predicts or determines the likelihood of ammonia slip when an increase in the fuel supply level is determined, and takes measures to attempt to prevent this ammonia slip. By directly heating SCR 123 or ASC 124, the ASC circuit 322 shortens the amount of time required for ASC 124 to reach its peak operating temperature, so that ASC 124 reaches its operating temperature approximately when the amount of unreacted ammonia reaches its peak.

[0112] Now for reference Figure 7AAccording to an exemplary embodiment, a flowchart of a first method 700 for ASC circuit 322 and controller 140 to raise the temperature of ASC 124 to reduce ammonia slip is shown. In process 710, controller 140 determines the likelihood of ammonia slip based on a sensing measurement of system output NOx (SONOx) (i.e., sensed by the system output or tailpipe NOx sensor) exceeding a sensing measurement of engine output NOx (EONOx) (i.e., sensed by the engine output NOx sensor). This is ammonia slip in relation to the likelihood of ammonia slip. If yes, method 700 proceeds to process 720 (710: Yes), in process 720, controller 140 determines whether the total fuel supply level to engine 110 exceeds a predetermined threshold. If no, method 700 returns to process 710 (720: No) to continue checking SONOx and EONOx. If yes, method 700 proceeds to process 730 (720: Yes), and controller 140 commands heater 125 to engage and slowly heat ASC 124. From process 730, method 700 proceeds to step 740, where controller 140 determines whether the temperature of ASC 124 exceeds a threshold (i.e., whether ASC 124 has reached its operating temperature). If the temperature of ASC 124 has not yet reached the threshold temperature, the method returns to process 730 (740: No) to continue heater 125 engagement. If the temperature of ASC 124 exceeds the threshold, method 700 continues to process 745, where controller 140 commands heater 125 to disengage.

[0113] Figure 7BThis is a flowchart of a second method 750 used by ASC circuit 322 and controller 140 to increase the temperature of ASC 124 to reduce ammonia slip. In process 760, controller 140 determines the possibility of ammonia slip based on a sensing reading of ammonia in the exhaust gas exceeding a threshold. If yes, method 750 proceeds to process 770 (760: Yes), where controller 140 determines whether the total fuel supply level to engine 110 exceeds a predetermined threshold. If no, method 750 returns to process 760 (770: No) to continue checking for ammonia in the exhaust gas. If yes, method 750 proceeds to process 780 (770: Yes), and controller 140 commands heater 125 to engage and slowly heat ASC 124. In some embodiments, “slow heating” refers to a flat rate of temperature increase of ASC 124 (e.g., 30°C / min), while in other embodiments, the rate at which heater 125 “slowly heats” ASC 124 is based on the current temperature of ASC 124 relative to a target ASC 124 temperature (e.g., “ignition” temperature). In these embodiments, the greater the difference between the current temperature and the target temperature, the greater the rate at which heater 125 heats ASC 124. Furthermore, this determination may include a comparison with a threshold such that if the difference between the current temperature and the target temperature exceeds the threshold, heater 125 is fully engaged (i.e., “on” at full power), and if the difference is less than the threshold, heater 125 is partially engaged (i.e., “on” at less than full power). From process 780, method 750 proceeds to process 790, where controller 140 determines whether the temperature of ASC 124 exceeds the threshold (i.e., whether ASC 124 has reached its operating temperature). If the temperature of ASC 124 has not yet reached the threshold, the method returns to process 780 (790: No) to continue heater 125 engagement. If the temperature of ASC 124 exceeds the threshold, method 750 continues to process 795, in which controller 140 commands heater 125 to disengage.

[0114] As used herein, the terms “approximately,” “about,” “substantially,” and similar terms are intended to have a broad meaning consistent with common and acceptable usage by those skilled in the art to which the subject matter of this disclosure relates. Those skilled in the art, upon reviewing this disclosure, will understand that these terms are intended to allow for the description of certain features described and claimed, without limiting the scope of those features to the precise numerical ranges provided. Therefore, these terms should be interpreted as indicating that non-substantial or irrelevant modifications or alterations to the described and claimed subject matter are considered to be within the scope of the disclosure set forth in the appended claims.

[0115] It should be noted that the term "exemplary" and its variations used herein to describe various embodiments are intended to indicate that these embodiments are possible examples, representations or illustrations of possible embodiments (and these terms are not intended to imply that these embodiments are necessarily special or superlative examples).

[0116] As used herein, the term "coupled" and its variations refer to two components that are directly or indirectly joined together. This connection can be static (e.g., permanent or fixed) or movable (e.g., removable or releasable). Such a connection can be achieved by directly coupling two components together, by coupling two components together using one or more separate intervening members, or by coupling two components together using an intervening member that forms a single, unified whole with one of the two components. If "coupled" or its variations are modified by an additional term (e.g., directly coupled), the general definition of "coupled" provided above is modified by the simple linguistic meaning of the additional term (e.g., "directly coupled" means a connection of two components without any separate intervening member), resulting in a narrower definition than the general definition of "coupled" provided above. This coupling can be mechanical, electrical, or fluid. For example, circuit A being communicatively "coupled" to circuit B could mean that circuit A communicates directly with circuit B (i.e., without an intermediary) or indirectly with circuit B (e.g., through one or more intermediaries).

[0117] References to the location of elements herein (e.g., “top,” “bottom,” “above,” “below”) are used only to describe the orientation of the various elements in the accompanying drawings. It should be noted that the orientation of the various elements may differ according to other exemplary embodiments, and such variations are intended to be included in this disclosure.

[0118] Although Figure 3 Various circuits with specific functions are shown herein; however, it should be understood that controller 140 may include any number of circuits for performing the functions described herein. For example, the activities and functions of SCR circuit 320 and ASC circuit 322 may be combined in multiple circuits or as a single circuit. Additional circuits with additional functions may also be included. Furthermore, controller 140 may further control other activities beyond the scope of this disclosure.

[0119] As described above, in one configuration, the "circuit" can be implemented in a machine-readable medium for use by various types of processors (e.g., Figure 3The executable code is executed by the processor 304. For example, executable code may include one or more physical or logical blocks of computer instructions, which may be organized, for example, into objects, procedures, or functions. However, executable files do not need to be physically located together, but may include different instructions stored in different locations that, when logically connected together, constitute a circuit and perform the circuit's stated purpose. In practice, the circuit of computer-readable program code can be a single instruction or multiple instructions, and can even be distributed across several different code segments, between different programs, and across several memory devices. Similarly, operational data can be identified and represented herein in a circuit, and can be embodied in any suitable form and organized in any suitable type of data structure. Operational data can be collected as a single dataset, or can be distributed across different locations, including across different storage devices, and can exist at least in part simply as electronic signals within a system or network.

[0120] Although the term "processor" has been briefly defined above, the terms "processor" and "processing circuit" are intended to be interpreted broadly. In this respect, as stated above, a "processor" can be implemented as one or more processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or other suitable electronic data processing components configured to execute instructions provided by memory. One or more processors can take the form of a single-core processor, a multi-core processor (e.g., a dual-core processor, a triple-core processor, a quad-core processor, etc.), a microprocessor, etc. In some embodiments, one or more processors can be external to the device; for example, one or more processors can be remote processors (e.g., cloud-based processors). Alternatively or additionally, one or more processors can be internal to the device and / or local. In this regard, a given circuit or its components can be locally located (e.g., as part of a local server, a local computing system, etc.) or remotely located (e.g., as part of a remote server such as a cloud-based server). Therefore, the "circuit" described herein can include components distributed in one or more locations.

[0121] Although the accompanying drawings and descriptions may show a specific order of method steps, this order may differ from that depicted and described unless otherwise specified above. Furthermore, two or more steps may be performed simultaneously or partially simultaneously unless otherwise specified above. For example, such variations may depend on the chosen software and hardware system and the designer's choices. All these variations are within the scope of this disclosure. Similarly, the software implementation of the described method can be accomplished using standard programming techniques with rule-based logic and other logic to perform various connection steps, processing steps, comparison steps, and decision steps.

Claims

1. A method comprising: The controller receives data regarding the operation of the exhaust aftertreatment system; The controller determines the presence of ammonia slip based on the data regarding the operation of the exhaust aftertreatment system; The controller determines the presence of ammonia storage based on the engine fuel supply rate exceeding a transient threshold. and The controller commands the heater to activate and heat a component of the exhaust aftertreatment system to reduce the amount of ammonia stored; the component is an ammonia escape catalyst (ASC).

2. The method according to claim 1, wherein, The condition for ammonia escape is at least one of the following: the system output NOx sensor reading exceeds the engine output NOx sensor reading or the ammonia sensor reading exceeds the ammonia escape threshold.

3. The method of claim 1, further comprising determining the ammonia storage level based on at least one of the following: a sensory measurement of NOx output from the engine, a sensory measurement of NOx output from the system, the feed rate of the diesel exhaust fluid, the exhaust flow rate, or the sensed temperature of the exhaust aftertreatment system. in, The condition for ammonia escape is that the determined ammonia storage amount exceeds the ammonia escape threshold.

4. The method according to any one of claims 1-3, wherein, The presence of the ammonia storage condition is also determined based on the ASC's sensing temperature being below a threshold.

5. The method according to claim 1, wherein, The heater is integrated into the ASC.

6. A system comprising: An exhaust aftertreatment system, which includes a heater; and A controller, coupled to the exhaust aftertreatment system, is configured to: Receive data regarding the operation of the exhaust aftertreatment system; Based on data regarding the operation of the exhaust aftertreatment system, conditions for ammonia escape were determined. The presence of ammonia storage was determined based on the engine fuel supply rate exceeding a transient threshold. and The heater is commanded to activate and heat a component of the exhaust aftertreatment system to reduce the amount of ammonia stored, the component being the ammonia escape catalyst (ASC).

7. The system according to claim 6, wherein, The condition for ammonia escape is at least one of the following: the system output NOx sensor reading exceeds the engine output NOx sensor reading or the ammonia sensor reading exceeds the ammonia escape threshold.

8. The system according to claim 6, wherein, The controller is also configured to: The ammonia storage level is determined based on at least one of the following: a sensing measurement of NOx output from the engine, a sensing measurement of NOx output from the system, or a sensing temperature from the exhaust aftertreatment system. The condition for ammonia escape is that the determined ammonia storage amount exceeds the ammonia escape threshold.

9. The system according to any one of claims 6-8, wherein, The presence of the ammonia storage condition is also determined based on the ASC's sensing temperature being below a threshold.

10. The system according to any one of claims 6-8, wherein, The transient threshold is a predetermined high fuel supply rate threshold for a predetermined time period.

11. The system according to claim 6, wherein, The heater is integrated into the ASC.

12. A non-transitory computer-readable storage medium comprising computer-readable instructions stored thereon, which, when executed by a processor of a controller, cause the controller to perform operations including: Receive data on the operation of the exhaust aftertreatment system, the data including at least one of the following: (i) a sensing measurement of NOx output from the engine and a sensing measurement of NOx output from the system or (ii) a sensing measurement of ammonia in the exhaust gas stream; The conditions for the existence of ammonia escape are determined based on the following: (i) the sensing value of NOx output by the system exceeds the sensing value of NOx output by the engine, or (ii) the sensing value of ammonia in the exhaust gas exceeds a threshold. The presence of ammonia storage is determined based on the engine fuel supply rate exceeding a transient threshold; and Based on the presence of the aforementioned ammonia slip, the heater is commanded to activate to heat a component of the exhaust aftertreatment system, namely the ammonia slip catalyst (ASC).

13. The non-transitory computer-readable medium according to claim 12, wherein, The conditions for determining ammonia storage include: Receive data regarding the amount of fuel supplied to the engine, which is coupled to the exhaust aftertreatment system; and Determining that the amount of fuel supplied to the engine exceeds a predetermined threshold is a prerequisite for commanding the heater to activate.

14. The non-transitory computer-readable medium according to claim 12 or 13, wherein, The operation also includes: Receive data on the temperature of the components of the exhaust aftertreatment system; and The heater is commanded to deactivate if the temperature exceeds a predetermined threshold temperature.

15. The non-transitory computer-readable medium according to claim 12, wherein, The heater is integrated into the ASC.

16. The non-transitory computer-readable medium according to claim 12, wherein, The operation also includes: Determine that the current temperature of the component is lower than the target temperature of the component by a greater than a threshold, and command the heater to activate at a first power level; or The current temperature of the component is determined to be less than a threshold value below the target temperature of the component, and the heater is commanded to activate at a second power level less than the first power level.

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