Patent Description:
Emissions regulations for internal combustion engines have become more stringent over recent years. Environmental concerns have motivated the implementation of stricter emission requirements for internal combustion engines throughout much of the world. Governmental agencies, such as the Environmental Protection Agency (EPA) in the United States, carefully monitor the emission quality of engines and set acceptable emission standards, to which all engines must comply. Consequently, the use of exhaust aftertreatment systems on engines to reduce emissions is increasing. A common component in many of these exhaust aftertreatment systems is a selective catalytic reduction (SCR) system, which reduces nitrous oxide (NOx) present in the exhaust gas by injecting a reductant into the flow of exhaust combined with the exhaust gas interacting with a catalyst. The catalyst reacts with the exhaust gas to form harmless nitrogen and water. However, the SCR is most effective at elevated operating temperatures, which means that its efficacy at colder temperatures is diminished.

<CIT> discloses an exhaust gas aftertreatment device, such as a selective catalytic reduction (SCR) device, located in an internal combustion engine exhaust system. A warm-up strategy of the exhaust gas aftertreatment device is initiated when the engine is operating, a temperature of the engine exceeds an engine temperature threshold, and a temperature of the exhaust gas aftertreatment device is less than a first exhaust gas aftertreatment device temperature threshold. The warm-up strategy is stopped when the exhaust gas aftertreatment device temperature exceeds a second exhaust gas aftertreatment device temperature threshold. The warm-up strategy may comprise at least one of retarding a timing of fuel injection into an engine cylinder, increasing a dwell time between a pilot fuel injection and a main fuel injection into an engine cylinder, and reducing an air-fuel ratio of the engine. Reducing the air-fuel ratio may be achieved by opening a turbocharger waste gate valve, or increasing an amount of exhaust gas recirculation (EGR).

<CIT> discloses an internal combustion engine system including an engine and an aftertreatment system that is connected to the engine to receive an exhaust flow from the engine. The aftertreatment system includes a contaminant storage catalyst for storing contaminants produced by the engine during cold start and low temperature operating conditions, and a NOx reduction catalyst downstream of the storage catalyst for receiving the contaminants released from the storage catalyst when temperature conditions in the exhaust flow and/or NOx reduction catalyst are above an effective temperature threshold for NOx reduction. A contaminant amount stored on the storage catalyst can be estimated in response to one or more operating parameters to manage a storage capacity of the storage catalyst. A bypass can used to bypass the storage catalyst to preserve storage capacity for a subsequent cold start condition.

One embodiment relates to a method according to the features of claim <NUM>.

In some of these embodiments, the information indicative of the operating status of the vehicle during the LEON mode includes at least one of a temperature of an aftertreatment system of the vehicle, a temperature of exhaust exiting the engine, a conversion efficiency of an selective catalytic reduction (SCR) catalyst of the aftertreatment system, a cumulative amount of system-out NOx, or a cumulative amount of soot on a diesel particulate filter (DPF) of the aftertreatment system. In other of these embodiments, the information indicative of the operating status of the vehicle during the TM mode includes at least one of a temperature of an aftertreatment system of the vehicle or a conversion efficiency of a selective catalytic reduction (SCR) catalyst of the aftertreatment system.

In further of these embodiments, disengaging the LEON mode is based on comparing the information indicative of the operating status of the vehicle during the LEON mode to one or more corresponding thresholds. In yet others of these embodiments, engaging the LEON mode includes at least one of increasing an exhaust gas recirculation (EGR) amount, retarding fuel injection timing, or modifying a common rail fuel pressure.

Another embodiment relates to a system that includes an aftertreatment system and a controller coupled to the aftertreatment system. The controller is configured to determine, based on a current temperature of the aftertreatment system, that the aftertreatment system is in a cold-operation mode; initiate a low engine-out NOx (LEON) mode by controlling a component of a vehicle containing the aftertreatment system to decrease an instantaneous engine-out NOx (EONOx) amount and to increase exhaust energy relative to a normal operation mode for an engine of the vehicle; receive information indicative of an operating status of the vehicle during the LEON mode; based on the information indicative of the operating status of the vehicle during LEON mode, disengage the LEON mode; subsequent to disengaging the LEON mode, initiate a thermal management (TM) mode for the aftertreatment system based on the information indicative of the operating status of the vehicle during the LEON mode, wherein the TM mode is initiated by controlling a component of the vehicle to increase fueling to the engine for a power level by reducing engine efficiency and directing excess fuel to the aftertreatment system; receive information indicative of an operating status of the vehicle during the TM mode; and based on the information indicative of the operating status of the vehicle during TM mode, disengage the TM mode.

Another embodiment relates to a controller for an aftertreatment system. The controller includes one or more processors and a memory storing instructions that, when executed by the one or more processors, cause the one or more processors to: determine, based on a current temperature of the aftertreatment system, that the aftertreatment system is in a cold-operation mode; initiate a low engine-out NOx (LEON) mode by controlling a component of a vehicle containing the aftertreatment system to decrease an engine-out NOx (EONOx) amount and to increase exhaust energy relative to a normal operation mode for an engine; receive information indicative of an operating status of the vehicle during the LEON mode; based on the information indicative of the operating status of the vehicle during LEON mode, disengage the LEON mode; subsequent to disengaging the LEON mode, initiate a thermal management (TM) mode for the aftertreatment system based on the information indicative of the operating status of the vehicle during the LEON mode; receive information indicative of an operating status of the vehicle during the TM mode; and based on the information indicative of the operating status of the vehicle during TM mode, disengage the TM mode.

Numerous specific details are provided to impart a thorough understanding of embodiments of the subject matter of the present disclosure. The described features of the subject matter of the present disclosure may be combined in any suitable manner in one or more embodiments and/or implementations. In this regard, one or more features of an aspect of the invention may be combined with one or more features of a different aspect of the invention. Moreover, additional features may be recognized in certain embodiments and/or implementations that may not be present in all embodiments or implementations.

This summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices or processes described herein will become apparent in the detailed description set forth herein, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements.

Following below are more detailed descriptions of various concepts related to, and implementations of, methods, apparatuses, and systems for operating and controlling an aftertreatment system during a cold-start warm-up period. Before turning to the figures, which illustrate certain exemplary embodiments in detail, it should be understood that the present disclosure is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting. For instance, as used within, "optimizing" should also be construed as including "nearly optimizing" or "substantially optimizing.

Referring to the figures generally, the various embodiments disclosed herein relate to systems, apparatuses, and methods for operating an aftertreatment system during a cold-start warm-up period.

A main component of exhaust gas aftertreatment systems is a Selective Catalytic Reduction (SCR) system that utilizes a two-step process to reduce harmful NOx emissions present in exhaust gas. First, a doser injects a reductant into the exhaust stream. This reductant may be a urea, diesel exhaust fluid (DEF), Adblue®, a urea water solution (UWS), an aqueous urea solution (e.g., AUS32, etc.), or another similar fluid that chemically binds to particles in the exhaust gas. Then, this mixture is run through an SCR catalyst that, when at a certain temperature, such as an SCR light off temperature (e.g., the temperature at which the SCR catalyst begins reacting), causes a reaction in the mixture that converts at least some of the harmful NOx particles into pure nitrogen and water. However, if the catalyst is not at the proper temperature, this conversion will not happen or will happen at a lower efficiency. Therefore, maintaining the catalyst temperature at a desired temperature or temperature range is impactful on the conversion efficiency of the catalyst. Heating the catalyst from a cold soak (or cold start) presents some difficulty. A common method of heating the SCR catalyst is to provide exhaust energy from the engine's hot exhaust gas (e.g., a high exhaust energy or HEE mode). However, in those situations in which the engine is starting from a cold soak (i.e., when the engine has been left off for an extended period of time, such as more than one hour), the SCR catalyst is not yet at the desired temperature, so the hot exhaust gas being provided from the engine is not being properly treated or reduced. Additionally, typical methods to elevate exhaust energy significantly compared to a normal, warm operation mode, result in a significantly higher EONOx flux from the engine system. As such, high levels of harmful NOx and hydrocarbon gases are being released into the atmosphere at possibly unacceptable or undesirable levels (e.g., exceeding one or more emissions regulations). In other words, trying to produce hot exhaust gas to heat the catalyst when the catalyst is not at a desired operating temperature may lead to the catalyst not reducing the harmful components in the exhaust gas during this warmup period. Therefore, balancing heating the SCR catalyst while keeping NOx and other regulated emissions low is desired. It is desirable that the catalyst reaches the operating temperature from a cold condition in a time span that is consistent with the rate of production of NOx emissions from the engine. A high rate of engine emissions during the warm-up period (such as in TM or HEE mode) dictates that the catalyst warms up quickly. A low emissions rate (such as in LEON mode) may allow the catalyst to warm up more slowly. Thus, both these cold operation modes (TM/HEE and LEON) have their respective advantages, and disadvantages. While TM mode allows the catalyst to warm up faster (relative to LEON mode), TM mode also generates a high level of untreated EONOx in that shorter period. While LEON mode takes a longer time to warm up the SCR (relative to TM mode), the flux of EONOx in that longer period is much lower than in TM mode. It is difficult without knowledge of drive cycles which mode will lead to an overall lower cumulative system out NOx (SONOx) penalty before catalyst warmup. Embodiments described herein balance these two modes to minimize overall SONOx put out into the environment during cold operation, for any unknown drive cycle.

As shown in <FIG>, a system <NUM> including an engine <NUM>, an aftertreatment system <NUM> coupled to the engine <NUM>, a controller <NUM>, and an operator input/output (I/O) device <NUM> is shown, according to an example embodiment. In this exemplary embodiment, the system <NUM> is implemented with an on-road or an off-road vehicle including, but not limited to, line-haul trucks, mid-range trucks (e.g., pick-up truck, etc.), sedans, coupes, tanks, airplanes, boats, and any other type of vehicle. In other embodiments, the system may be implemented with stationary pieces of equipment like power generators or gen-sets. The system <NUM> may mitigate high NOx and other harmful emissions during a warmup period for the engine and catalyst of the aftertreatment system.

The engine <NUM> may be any type of engine that generates exhaust gas, such as an internal combustion engine (e.g., compression ignition or a spark ignition engine that may utilize various fuels, such as natural gas, gasoline, diesel fuel, jet fuel, etc.), a hybrid engine (e.g., a combination of an internal combustion engine and an electric motor), or any other suitable engine. The engine <NUM> includes one or more cylinders and associated pistons. In this regard, air from the atmosphere is combined with fuel, and combusted, to power the engine <NUM>. Combustion of the fuel and air in combustion chambers <NUM> of the engine <NUM> produces exhaust gas that is operatively vented to an exhaust pipe and to the aftertreatment system <NUM>. In the example shown, the engine <NUM> is structured as an internal combustion engine and particularly, a compression-ignition engine powered by diesel fuel.

The system <NUM> is also shown to include an air intake system <NUM> structured to deliver a flow of air into the combustion chambers <NUM> of the engine <NUM>, and a fuel injection system <NUM> structured to receive fuel from a fuel source <NUM> (e.g., fuel tank) and inject fuel into the combustion chambers <NUM> of the engine <NUM>. In one embodiment and as shown, the fuel injection system <NUM> delivers the fuel to the engine <NUM> via a common rail. In these embodiments, the pressure of the common rail can be managed in order to affect the atomization of the fuel as the fuel is injected. Greater common rail pressure begets greater production of NOx. In some embodiments, the fuel injection system <NUM> may utilize a multiple injection cycle such that a main injection of fuel for combustion is followed by another, smaller injection of fuel. Injections following the main injection for combustion are known as post-injections. Post injection refers to fuel that is injected later in the combustion stroke - which may or may not combust in the cylinder. By altering the quantities and timings of the multiple injection cycle, the amount of NOx being produced by the engine <NUM> can be controlled. For example, retarding fuel injection timing in the fuel injection system <NUM> can decrease the NOx output from the engine <NUM>.

The air intake system <NUM> is coupled to an EGR system <NUM> that includes an EGR valve that directs a portion of the exhaust gas from the engine <NUM> back towards the engine <NUM> rather than allowing that exhaust gas to pass through the aftertreatment system <NUM> and into the atmosphere. By mixing the exhaust gas with the intake air in the combustion chambers <NUM> of the engine <NUM>, thermal characteristics of the combustion charge are altered such that in certain situations lower NOx or other undesired emission products is produced. Additionally, more EGR may result in higher particulate matter emissions. However, additional EGR amounts may lead to a reduction in some emission types, such as NOx, due to EGR tending to lower combustion temperatures. The system <NUM> may also include an EGR cooler position upstream of the engine <NUM> to reduce the temperature of the hot exhaust gases prior to mixing with fresh intake charge to improve thermal efficiency of combustion by reducing charge temperatures. Flowing EGR can come with a "pumping" penalty, increasing engine fuel consumption to maintain a given power level. The power level refers to a power output from the engine. Based on various conditions, this power level corresponds with specific fueling for a given brake specific fuel consumption (BSFC). As described herein, excess fueling (e.g., above the fueling required to maintain the BSFC (e.g., a specific or given power level) may be commanded in the TM mode by intentionally reducing engine efficiency by means such as overclosing the VG or applying an exhaust throttle, and directing at least some (in particular, a majority of the excess fuel energy) to the aftertreatment system. Manipulating the EGR amount can affect emission characteristics as well as engine efficiency.

As also shown in <FIG>, the system <NUM> includes a turbocharger that is shown as a combination of a compressor <NUM> and a turbine <NUM>. Exhaust gas of the combustion is discharged to the turbine <NUM>, which is mechanically coupled to the compressor <NUM> through, for example, a shaft, and drives the compressor <NUM>. A wastegate <NUM> can enable part of the exhaust gas to bypass the turbine <NUM>, resulting in less power transfer to the compressor <NUM>. A combination of bypass and turbine flow enters the aftertreatment system <NUM> for aftertreatment before being released to the atmosphere. In one embodiment, the system <NUM> may include a Variable Geometry Turbine (VGT) instead of the wastegate <NUM>. The VGT is structured to flexibly modulate the power transferred to the turbine <NUM> by changing a position of a valve of the VGT. The compressor <NUM> may compress air before the air is aspirated into the air intake system <NUM> through an air intake passage, thereby increasing the temperature and pressure of the air flow. The system <NUM> may also include a charge air cooler that is positioned downstream of the compressor <NUM> and is structured to reduce the temperature and increase a density of the intake air, thereby improving efficiency by reducing loss due to the increase in temperature of the air from compression. Operation of the turbocharger also affects exhaust energy output from the system <NUM>. In some embodiments, the air intake system <NUM> includes an air intake manifold, an air intake throttle, and/or an air intake valve structured to control access of the air to the combustion chambers <NUM>.

As the exhaust gas drives the turbine <NUM> to rotate, the compressor <NUM> compresses the air supplied to the combustion chambers <NUM> of the engine <NUM>. The wastegate <NUM>, by diverting some exhaust gas from the turbine <NUM>, reduces the power transferred to the compressor <NUM>, thereby reducing the rate at which the air flow is supplied to the combustion chambers <NUM> of the engine <NUM>. Conversely, if the wastegate <NUM> is closed, all or mostly all of the exhaust gas is directed to the turbine <NUM>, increasing the amount of power transferred to the compressor <NUM> and increasing the rate of air flow into the combustion chambers <NUM> of the engine. In one embodiment in which the wastegate <NUM> is replaced by the VGT, the VGT may change the turbine power by controlling the vane position in the VGT. The VGT allows the system to achieve an optimum aspect ratio. If the aspect ratio is large (i.e. more opened) the power transferred by the turbine <NUM> to the compressor <NUM> is low, thus reducing an achievability of a high boost pressure (e.g. at idle). Conversely, if the aspect ratio is small (i.e. less opened), the power transferred by the turbine <NUM> to the compressor <NUM> is high, and thereby the compressor can supply more air to the combustion chamber through the air intake system <NUM>. Altering operation of the turbocharger can affect combustion efficiency. For example, increasing the air flow (i.e. a smaller aspect ratio) increases the air content of the air-fuel mixture in the combustion chambers <NUM>, which increases a combustion efficiency of the mixture. Combustion efficiency refers to how much energy is being extracted from a given amount of provided fuel. One-hundred percent combustion efficiency indicates that all of the energy in the amount of fuel has been extracted into useful work. This level of combustion efficiency is practically not obtainable given the dynamics of an engine system and the losses associated therewith. Other functions of the VGT include increasing back pressure (exhaust pressure) to drive EGR, and in other instances overclosing or opening completely to significantly diminish turbocharger efficiency with the objective of overfueling the engine at a given power level to divert a higher fraction of the fuel energy into the exhaust stream for aftertreatment thermal management, or to function as an engine brake. Together with operation of the turbocharger, operation of the EGR system <NUM> can affect combustion stability and emissions from the engine (e.g., NOx, HC, PM, etc.). High fractions of air in the air intake system <NUM> caused by high compressor <NUM> power (i.e. a "leaner" combustion) may enhance combustion stability, thereby reducing PM and HC emissions. However, such leaner combustion may lead to high combustion temperatures, thereby producing more NOx. Optimal operation of the turbocharger and EGR system <NUM> can allow the engine <NUM> to achieve optimal combustion efficiency while minimizing emissions through changing conditions. In one embodiment, there is an exhaust throttle valve (ETV) downstream of the turbine of the turbocharger which is used to modulate engine backpressure and pumping for applications like engine braking and aftertreatment thermal management.

A combination of bypass flow and turbine flow may enter the aftertreatment system <NUM>. The aftertreatment system <NUM> is shown to include an SCR system <NUM>.

The SCR system <NUM> is structured to receive exhaust gas in a decomposition chamber (e.g. reactor, reactor pipe, etc.), in which the exhaust gas is combined with a reductant, which may be, for example, urea, diesel exhaust fluid (DEF), Adblue®, a urea water solution (UWS), an aqueous urea solution (e.g., AUS32, etc.), or other similar fluids. An amount of reductant is metered by a dosing system <NUM>. The decomposition chamber includes an inlet in fluid communication with the EGR system <NUM> to receive the exhaust gas containing NOx emissions and an outlet for the exhaust gas-reductant mixture to flow to a SCR catalyst <NUM>. The SCR catalyst <NUM> is configured to assist in the reduction of NOx emissions by accelerating a NOx reduction process between the reductant and the NOx of the exhaust gas into diatomic nitrogen, water, and/or carbon dioxide. The SCR catalyst <NUM> may be made from a combination of an inactive material and an active catalyst, such that the inactive material, (e.g. ceramic metal) directs the exhaust gas towards the active catalyst, which is any sort of material suitable for catalytic reduction (e.g. base metals oxides like vanadium, molybdenum, tungsten, etc. or noble metals like platinum). If the SCR catalyst <NUM> is not at or above a certain temperature, the rate of the NOx reduction process is limited and the SCR system <NUM> will not operate at a desired level of efficiency to meet various regulations. In some embodiments, this certain temperature is a temperature range corresponding to <NUM>-<NUM>. In other embodiments, the certain operating temperature corresponds with the conversion efficiency of the SCR catalyst <NUM> meeting or exceeding a predefined conversion efficiency threshold (e.g., sixty-percent as in sixty-percent of NOx is converted to less harmful elements). Other catalyst elements in the system such as a DOC or AMOX may also desired increased temperature levels to achieve desired operating efficiencies (e.g., NOx reduction or other emissions type) and, in turn, have their own certain desired operating temperature thresholds or ranges.

The efficiency of the NOx reduction process is also affected by the amount of reductant injected into the decomposition chamber by the dosing system <NUM>. Generally, the more reductant that is present in the resultant exhaust gas-reductant mixture, the more of the NOx in the exhaust gas that is reduced. Although there is a point at which too much reductant in the mixture can lead to a separate set of problems (e.g. ammonia slip). The general principle is that increasing the amount of reductant injected by the dosing system <NUM> improves the reductive capabilities of the SCR system <NUM>, thereby reducing the amount of NOx and other regulated emissions released into the atmosphere. In some embodiments, the aftertreatment system <NUM> includes an ammonia oxidation catalyst (AMOX) <NUM> that is structured to address ammonia slip by removing excess ammonia from the treated exhaust gas before the treated exhaust is released into the atmosphere.

In some embodiments, the aftertreatment system <NUM> further includes a diesel oxidation catalyst (DOC) <NUM> that is structured to receive a flow of exhaust gas and to oxidize hydrocarbons and carbon monoxide in the exhaust gas. In some embodiments and depending on the system architecture, the aftertreatment system <NUM> may further include a three-way catalyst (not shown) that is structured to receive a flow of exhaust gas and to reduce NOx into nitrogen and water and to oxidize hydrocarbons and carbon monoxide in the exhaust gas (i.e. perform the combined functions of the SCR catalyst <NUM> and of the DOC <NUM>). The aftertreatment system <NUM> may also include a diesel particulate filter (DPF) <NUM> is arranged or positioned downstream of the DOC <NUM> and structured to remove particulates, such as soot, from exhaust gas flowing in the exhaust gas stream. The DPF <NUM> includes an inlet, where the exhaust gas is received, and an outlet, where the exhaust gas exits after having particulate matter substantially filtered from the exhaust gas and/or converting the particulate matter into carbon dioxide. In some implementations, the DPF <NUM> may be omitted.

Briefly referencing <FIG>, as also shown, a sensor array <NUM> is included in the aftertreatment system <NUM>. The sensors are coupled to the controller <NUM>, such that the controller <NUM> can monitor and acquire data indicative of operation of the vehicle and system <NUM>. In this regard, the sensor array includes NOx sensors <NUM>, flow rate sensors <NUM>, and temperature sensors <NUM>. The NOx sensors <NUM> acquire data indicative of or, if virtual, determine a NOx amount at or approximately at their disposed location. The flow rate sensors <NUM> acquire data indicative of or, if virtual, determine an approximate flow rate of the exhaust gas at or approximately at their disposed location. The temperature sensors <NUM> acquire data indicative of or, if virtual, determine an approximate temperature of the exhaust gas at or approximately at their disposed location. It should be understood that the depicted locations, numbers, and type of sensors is illustrative only. In other embodiments, the sensors may be positioned in other locations, there may be more or less sensors than shown, and/or different/additional sensors may also be included with the system <NUM> (e.g., a pressure sensor, etc.). Those of ordinary skill in the art will appreciate and recognize the high configurability of the sensors in the system <NUM>.

The controller <NUM> is structured or configured to control the system <NUM> in order to balance usage of special operation modes, which include a Low Engine-Out NOx (LEON) mode and a Thermal Management (TM) mode, in order to keep an overall tailpipe NOx (TPNOx) burden below a threshold during the period of 'cold operation,' with is defined as a period of time from a 'cold start' to 'warm operation. ' "Cold start" refers to the period of time when a temperature of the aftertreatment system <NUM> (e.g., of the aftertreatment system <NUM> generally, of the SCR catalyst <NUM>, etc.) is at or near a low temperature threshold. "Warm operation" refers to the temperature of the aftertreatment system <NUM> (e.g., of the aftertreatment system generally, of the SCR catalyst <NUM>, etc.) at or near an operating temperature threshold. In some embodiments, this operating temperature threshold is a temperature range corresponding to <NUM>-<NUM>. In other embodiments, the certain operating temperature corresponds with the conversion efficiency of the SCR catalyst <NUM> meeting or exceeding a pre-defined conversion efficiency threshold (e.g., sixty-percent as in sixty-percent of NOx is converted to less harmful elements). Overall, the TPNOx (also referred to as System Out NOx - SONOx) burden during cold operation is a function of a rate of Engine-Out NOx (EONOx) and the time taken for the SCR catalyst <NUM> to reach temperatures that provide acceptable conversion efficiency. This period of time is defined herein as the "cold start" to "warm operation" time range.

LEON mode refers to a low EONOx operating mode. During the LEON mode, the controller <NUM> prioritizes a lower EONOx rate (by, e.g., retarding fuel injection timing, increasing EGR amounts, etc.) to reduce the TPNOx burden that typically comes at the expense of fuel consumption compared to normal operation mode operation with a warmed up SCR for a particular point in time (particularly, up until SCR <NUM> reaches a suitable temperature for an acceptable NOx conversion efficiency). Lower EONOx rates generally follow from increased EGR levels. Whereas in TM mode (also known as High Exhaust Energy (HEE) mode), the system <NUM> is biased to significantly increase exhaust enthalpy (in relation to normal operation mode as indicated below), at the expense of significantly higher EONOx (due to significantly higher fueling needed, a large portion of which is directed to the exhaust). In comparison to normal operation mode, LEON mode biases the engine system to reduce EONOx significantly (in relation to Normal mode), while moderately increasing exhaust energy in comparison to normal mode.

Another operating mode includes a thermal management for the engine (TM mode). In comparison to the LEON mode, the TM mode, also known as High Exhaust Energy (HEE) mode, prioritizes a shorter colder operation period by increasing exhaust enthalpy intensity (e.g., restrictive engine breathing leading to over-fueling the engine <NUM>, etc.), which leads to a higher amount of CO<NUM> and a higher EONOx burden because the methods used to increase exhaust enthalpy intensity generally result in higher NOx production. In operation and as described herein, the controller <NUM> selectively prioritizes the lower EONOx rate (via the LEON mode) or the higher EONOx rate (via the TM mode) in order to optimize the overall cold-operation NOx burden.

The controller <NUM> is configured to engage the LEON mode upon start-up, if the temperature of the aftertreatment system <NUM> (or of the SCR catalyst <NUM> in particular) qualifies the system <NUM> as being in cold operation and as below a threshold (particularly, a temperature threshold) for initiating the LEON mode. The controller <NUM> maintains the LEON mode until the controller <NUM> determines that the LEON mode is insufficient. This determination is made based on an analysis and evaluation of operating parameters in real-time comparison to operating thresholds (e.g., an amount of TPNOx). For example, if the amount of TPNOx exceeds a predefined threshold, the controller <NUM> determines that LEON mode is insufficient for the task of warming the SCR catalyst <NUM> within a NOx budget. The amount of TPNOx may be, in some embodiments, estimated using the speed/load trajectory of the system <NUM> to consult a steady-state EONOx map, which is stored in the memory <NUM> or as part of a virtual NOx sensor. The predefined threshold is based on an amount of TPNOx that indicates that the system <NUM> will exceed or is exceeding an acceptable amount of NOx emissions prior to the SCR catalyst reaching an operating temperature based on the lower enthalpy intensity of LEON mode. If the controller <NUM> determines that LEON mode is insufficient, the controller <NUM> exits LEON mode and initiates the TM mode. The TM mode is employed to rapidly warm up the aftertreatment system <NUM> at the cost of higher instantaneous EONOx (and thus higher TPNOx prior to warm operation). Once the controller <NUM> determines that the aftertreatment system <NUM> is no longer in cold operation based on the temperature of the aftertreatment system <NUM> (e.g., of the aftertreatment system <NUM> generally, of the SCR catalyst <NUM>, etc.) exceeding an operating temperature threshold, the controller <NUM> disengages whichever special operation mode (LEON or TM) is currently engaged and initiates normal operation of the system <NUM>.

As the components of <FIG> are shown to be embodied in the system <NUM> of the vehicle, the controller <NUM> may be structured as one or more electronic control units (ECU). The function and structure of the controller <NUM> is described in greater detail in <FIG>.

Referring now to <FIG>, a schematic diagram of the controller <NUM> of the system <NUM> of <FIG> is shown according to an example embodiment. As shown in <FIG>, the controller <NUM> includes a processing circuit <NUM> having a processor <NUM> and a memory <NUM>, a initiator circuit <NUM>, a LEON exit circuit <NUM>, a TM exit circuit <NUM>, and a communications interface <NUM>. Generally, the controller <NUM> is structured to determine a proper operating mode for the system <NUM> and to control components of the system in order to manage transitions between the operating modes.

In one configuration, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> are embodied as machine or computer-readable media storing instructions that are executable by a processor, such as processor <NUM>. As described herein and amongst other uses, the machine-readable media facilitates performance of certain operations to enable reception and transmission of data. For example, the machine-readable media may provide an instruction (e.g., command, etc.) to, e.g., acquire data. In this regard, the machine-readable media may include programmable logic that defines the frequency of acquisition of the data (or, transmission of the data). The computer readable media instructions may include code, which may be written in any programming language including, but not limited to, Java or the like and any conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program code may be executed on one processor or multiple remote processors. In the latter scenario, the remote processors may be connected to each other through any type of network (e.g., CAN bus, etc.).

In another configuration, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> are embodied as hardware units, such as electronic control units. As such, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc. In some embodiments, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of "circuit. " In this regard, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on). The initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. The initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may include one or more memory devices for storing instructions that are executable by the processor(s) of the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM>. The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory <NUM> and processor <NUM>. In some hardware unit configurations, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may be geographically dispersed throughout separate locations in the vehicle. Alternatively and as shown, the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may be embodied in or within a single unit/housing, which is shown as the controller <NUM>.

In the example shown, the controller <NUM> includes the processing circuit <NUM> having the processor <NUM> and the memory <NUM>. The processing circuit <NUM> may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM>. The depicted configuration represents the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> as machine or computer-readable media storing instructions. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments where the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM>, or at least one circuit of the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM>, is configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure.

The processor <NUM> may be implemented as a single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a 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. A processor may be a microprocessor. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, the one or more processors may be shared by multiple circuits (e.g., the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may comprise or otherwise share the same processor which, in some example embodiments, may execute instructions stored, or otherwise accessed, via different areas of memory). Alternatively or additionally, the one or more processors may be structured to perform or otherwise execute certain operations independent of one or more co-processors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure.

The memory <NUM> (e.g., memory, memory unit, storage device) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory <NUM> may be communicably connected to the processor <NUM> to provide computer code or instructions to the processor <NUM> for executing at least some of the processes described herein. Moreover, the memory <NUM> may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory <NUM> may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.

The initiator circuit <NUM> is configured or structured to receive information indicative of a starting the vehicle in which the system <NUM> is contained and to determine an initial operating mode. The "starting" of the vehicle may be based on receiving an indication of a push-button start, a key-on position, or any other operating point that indicates that the engine has been turned on. The initial operating mode refers to the mode of operation for the system upon starting (e.g., LEON mode, TM mode, normal operation mode). In addition to the information indicating whether the vehicle and engine are "on," additional information at and during starting includes a temperature of the aftertreatment system <NUM>, a temperature of the SCR catalyst <NUM>, an ambient temperature around the vehicle, etc. The temperature of the aftertreatment system <NUM> may be determined by the temperature sensors(s) <NUM>. The temperature may be a temperature of a particular component of the aftertreatment system <NUM> (such as of the SCR catalyst <NUM>), an average temperature of a component of interest of the aftertreatment system <NUM>, or as a temperature of the exhaust gas entering the aftertreatment system <NUM> (or at another location). In some embodiments, the determination of the initial operating mode is based on a temperature of the aftertreatment system <NUM>. In other embodiments, the determination includes a consideration of the ambient temperature. Once the controller <NUM> receives the temperature(s) from the various sensor(s) of the sensor array <NUM>, the initiator circuit <NUM> compares the temperature(s) to one or more threshold(s). In one embodiment, the initiator circuit <NUM> compares the temperature of the aftertreatment system <NUM> to a cold-operation threshold. If the temperature of the aftertreatment system <NUM> is below the cold-operation threshold, the initiator circuit <NUM> determines that the aftertreatment system <NUM> is experiencing a cold-operation condition. This cold-operation threshold may be a predefined value of a desired operating temperature of the aftertreatment system <NUM>. The threshold may be specific to certain components or to the system <NUM> as a whole. If the temperature of the aftertreatment system <NUM> is below the cold-operation threshold, the controller <NUM> determines that the aftertreatment system <NUM> is below a desired operating temperature, such that the aftertreatment system <NUM> is not effectively reducing harmful components in the exhaust gas (e.g., NOx). If the temperature of the aftertreatment system <NUM> is at or above the cold-operation threshold, the initiator circuit <NUM> determines that the initial operating mode for the system <NUM> is normal operation (i.e., the vehicle is already prepared for warm operation and is focused on optimizing fuel efficiency).

Once the initiator circuit <NUM> determines that the aftertreatment system <NUM> is in a cold-operation condition, the initiator circuit <NUM> compares the aftertreatment system <NUM> temperature to a LEON mode entry threshold. If the temperature of the aftertreatment system <NUM> is below the LEON mode entry threshold, the initiator circuit <NUM> determines that the initial operating mode for the system <NUM> is LEON mode. In some embodiments in which avoiding the LEON mode is preferred (such as for performance considerations), the LEON mode entry threshold is a first temperature (e.g., <NUM>), so that the system <NUM> is initiated in LEON mode substantially only when the system <NUM> is started from a complete cold-start. In other embodiments in which LEON is a preferred initial mode, the LEON entry threshold is a second temperature that is substantially the same as the cold-operation threshold (e.g., <NUM>-<NUM>), so that the system <NUM> is initiated in LEON is almost every scenario except those in which the system <NUM> is already prepared for warm-operation.

The initiator circuit <NUM> engages LEON mode by sending command signals to various components of the system <NUM> to adjust performance and achieve or substantially achieve low EONOx. For example, the initiator circuit <NUM> commands the EGR system <NUM> to increase an EGR amount returning to the combustion chambers <NUM>, In another example, the initiator circuit <NUM> commands the fuel injection system <NUM> to retard fuel injection timing (and to increase fueling respectively in order to maintain power output) or commands the fuel injection system <NUM> to initiate post-injections, which increase an amount of energy directed to the aftertreatment system <NUM> (i.e., increase the enthalpy intensity) without increasing EONOx. In another example, the initiator circuit <NUM> initiates LEON mode by reducing the common rail pressure in order to reduce production of NOx. In some embodiments, the initiator circuit <NUM> commands multiple components of the system <NUM> (in one embodiment, concurrently) in order to achieve or attempt to achieve low EONOx through the combined actuations of the commanded multiple components. For example, in these embodiments, the initiator circuit <NUM> may command an increased EGR amount, a retarded fuel timing, and an optimized common rail pressure targeting the desired EONOx/particulate matter tradeoff.

The LEON exit circuit <NUM> is configured or structured to receive information indicative of an operating status of the vehicle in which the system <NUM> is contained while the system <NUM> is operating in LEON mode, to determine when to disengage LEON mode, and to determine a subsequent operating mode. The information indicative of the operating status of the system <NUM> in LEON mode includes a temperature of the aftertreatment system <NUM>, a temperature of the engine-out exhaust, a conversion efficiency of the SCR catalyst <NUM> (a NOx conversion efficiency), an amount of TPNOx (either accumulated or instantaneous), an amount of soot on the DPF <NUM>, etc. The temperature of the aftertreatment system <NUM> may be based on at least one of a temperature of components of the aftertreatment system <NUM>, including the SCR catalyst <NUM>, the DOC <NUM>, or the DPF <NUM>. The conversion efficiency of the SCR catalyst <NUM> can be determined based on the temperature of the SCR catalyst or based on an amount of NOx in the exhaust measured by the NOx sensors <NUM> before the SCR catalyst <NUM> and after the SCR catalyst <NUM>. The amount of soot of the DPF <NUM> may be estimated based on a mass flow rate of the exhaust measured by the flow rate sensors <NUM> before the DPF <NUM> and after the DPF <NUM> or on an exhaust pressure of the exhaust measured before the DPF <NUM> and after the DPF <NUM>, or based on a lookup table containing estimated soot flux as a function of speed, load, environmental conditions, and other quantities during a certain operation period.

The LEON exit circuit <NUM> determines whether to disengage LEON mode based on a comparison of the information indicative of the operating status of the vehicle to one or more thresholds. In some embodiments, the LEON exit circuit <NUM> determines to disengage LEON mode and to engage normal operation when the temperature of the aftertreatment system <NUM> exceeds a warm-operation temperature threshold or when the conversion efficiency of the SCR catalyst <NUM> exceeds a warm-operation conversion efficiency threshold. In these embodiments, the LEON exit circuit <NUM> determines to disengage LEON mode and to engage normal operation because the controller <NUM> determines that the system <NUM> is prepared for warm-operation. The warm-operation temperature threshold refers to a temperature at which the SCR catalyst <NUM> is efficiently converting NOx in the exhaust (e.g., <NUM>) above a predefined conversion efficiency value. If the temperature is not readily determined, the warm-operating temperature threshold may be determined as being exceeded based on the conversion efficiency exceeding a predefined value. The warm-operation conversion efficiency threshold refers to an acceptable conversion efficiency for the SCR. The acceptable conversion efficiency value may be defined by a regulation such that the SCR is desired to convert NOx to at or above the regulated value (e.g., <NUM>%, meaning that <NUM>% of the EONOx in the exhaust is reduced by the SCR system <NUM>). As such, in some embodiments, the warm-operation temperature threshold is the same as the cold-operation threshold.

In other embodiments, the LEON exit circuit <NUM> determines to disengage the LEON mode and to engage the TM mode when the temperature of the aftertreatment system is below the warm-operation temperature threshold and the SCR catalyst conversion efficiency is below the warm-operation conversion efficiency threshold (i.e., the 'warm-operation parameters' are not met, such that the SCR catalyst <NUM> is not converting NOx at a predefined conversion efficiency value), but one or more of the other operating parameters are above their respective thresholds. These other operating parameters include an accumulated amount of EONOx, an accumulated amount of TPNOx, an estimated amount of soot on the DPF <NUM>. For example, if the warm-operation parameters are below their respective thresholds but an accumulated amount of EONOx exceeds a LEON EONOx threshold, the LEON exit circuit <NUM> determines to disengage the LEON mode and to engage the TM mode because the controller <NUM> has determined that the LEON mode is not sufficient to warm the aftertreatment system <NUM> to warm-operation levels within the TPNOx budget. The accumulated amount of EONOx is determined according to the following formula: <MAT> where, t is equal to the time since the engine <NUM> is keyed on, t<NUM> is the time at which the accumulated amount of EONOx is determined (e.g., at SCR <NUM> light off), and EONOx is a rate of EONOx at an instant t in time. If the EONOx sensor has woken up (i.e., is active), the value of EOṄOx is based on an actual value received from that sensor. If the EONOx sensor is still asleep (i.e., inactive), the value of EOṄOx is determined using a stored steady-state EONOx map in which a value of EOṄOx can be estimated based on a speed and/or load of the engine <NUM>. In this example, TPNOx can be used instead of EONOx, such that an accumulated amount of TPNOx is compared against a LEON TPNOx threshold, and such that TPNOx can be used in the place of EONOx for formula <NUM>.

In other embodiments, the LEON exit circuit <NUM> determines to disengage LEON mode and to engage TM mode if the warm-operation parameters are below their respective thresholds but the amount of soot build-up on the DPF <NUM> has exceeded a LEON soot threshold. The LEON soot threshold may be a pre-defined value based on an amount of soot accumulation at which desired exhaust flow rate is possible from an engine/aftertreatment performance as well as aftertreatment protection standpoints. Because less heat energy is directed to the aftertreatment system <NUM> during LEON mode, more soot builds up on the DPF <NUM> due to the lack of passive regeneration (i.e., less soot is burned off of the DPF <NUM>). Additionally, the LEON combustion process itself may produce more soot than when the system is in normal operation mode, as a combination of a cold engine, higher levels of EGR, retarded injection and potentially lower injection pressure serve to reduce NOx at the expense of higher soot production. Soot build-up on the DPF <NUM> is disadvantageous for engine <NUM> performance because soot on the DPF <NUM> restricts exhaust flow causing an increase in pumping work and thus increase in fuel consumption. As such, if the LEON exit circuit <NUM> determines than the amount of soot buildup is negatively affecting engine <NUM> or aftertreatment system <NUM> performance (based on the amount of soot build-up on the DPF <NUM> exceeding a LEON soot threshold), which in some extreme case can cause a catastrophic DPF <NUM> failure where a thermal event (such as suddenly higher exhaust temperatures) could generate a high level of exotherm by igniting the accumulated carbon deposits and melting the DPF <NUM> material, the LEON exit circuit <NUM> determines to disengage LEON mode and to engage TM mode, in which higher amounts of energy directed to the aftertreatment system <NUM> to burn off some of the accumulated soot deposits.

The LEON exit circuit <NUM> engages TM mode by sending command signals to various components of the system <NUM> to adjust performance. For example, the LEON exit circuit <NUM> engages TM mode by "overclosing" the VGT of the turbocharger <NUM>, which has the effect of choking the engine, thus requiring significant overfueling (i.e., increasing the fueling amount above standard amounts) in order to maintain the desired power output. Some of the excess fuel energy generated by the overfueling (i.e., the amount of fuel energy not directed to generating power output) is directed to warming the aftertreatment system <NUM>. In one example, the LEON exit circuit <NUM> commands the EGR system <NUM> to reduce an EGR amount returned to the combustion chambers <NUM>. However, if the LEON exit circuit <NUM> has overclosed the VGT of the turbocharger, the increase in pressure on the engine <NUM> makes it difficult to control EGR flow, so commands to deliver the same high levels of EGR amount as LEON may not be combined with commands to overclose the VGT.

The TM exit circuit <NUM> is configured or structured to receive information indicative of an operating status of the vehicle in which the system <NUM> is contained while the system <NUM> is operating in TM mode and to determine when to disengage LEON mode for the normal operation mode based on the received information. Normal operation mode refers to a standard operation for the engine where the system <NUM> is not operating in a special operation mode (e.g., LEON mode or TM mode). The information indicative of the operating status of the system <NUM> in TM mode includes a temperature of the aftertreatment system <NUM>, temperatures of components of the aftertreatment system <NUM> (most notably of the SCR catalyst <NUM>), and the conversion efficiency of the SCR catalyst <NUM>. In some embodiments, the TM exit circuit <NUM> determines to disengage TM mode and to engage normal operation when the temperature of the aftertreatment system <NUM> exceeds the warm-operation temperature threshold or when the conversion efficiency of the SCR catalyst <NUM> exceeds the warm-operation conversion efficiency threshold. In some of these embodiments, the TM exit circuit <NUM> determines this as an either/or function, such that only one of the aftertreatment system <NUM> temperature or the SCR catalyst <NUM> conversion efficiency exceeds their respective threshold in order to disengage TM mode. In other embodiments, the TM exit circuit determines this based on both of the aftertreatment system <NUM> temperature and the SCR catalyst <NUM> conversion efficiency exceeding their respective thresholds in order to disengage the TM mode. In these embodiments, the TM exit circuit <NUM> determines to disengage TM mode and to engage normal operation because the controller <NUM> determines that the system <NUM> is prepared for warm-operation.

Referring now to <FIG>, a method <NUM> for reducing an accumulated amount of NOx during cold operation, which is defined as a period of time from engine <NUM> key-on until when the aftertreatment system <NUM> (particularly the SCR catalyst <NUM>) reaches an operational temperature, is shown. In some embodiments, the method may be performed by the controller <NUM> of <FIG>. The method <NUM> begins at <NUM>, when the engine <NUM> is keyed-on. Then, at <NUM>, the controller <NUM> determines whether the system <NUM> is beginning in cold operation. This determination is made based on an evaluation of current temperatures of the aftertreatment system <NUM> and/or of the ambient air, and a comparison of these temperatures to thresholds. For example, if the controller <NUM> determines that the current temperature of the aftertreatment system <NUM> exceeds a warm-operation threshold, the controller <NUM> determines that the system <NUM> is not in cold operation and the method proceeds to <NUM> (<NUM>: NO). Alternatively, if the current temperature is below a warm-operation threshold, the controller determines that the system <NUM> is starting in cold operation and proceeds to initiate LEON mode at <NUM> (<NUM>: YES).

At <NUM>, the controller <NUM> engages LEON mode by commanding one or more components of the system <NUM>. The method <NUM> then proceeds to <NUM>, where the controller <NUM> determines if warm-operation thresholds have been met. The determination at <NUM> is similar to the determination made at <NUM>, in that if the thresholds are met (e.g., temperature of aftertreatment system <NUM> above warm-operation threshold), the method proceeds to <NUM> and engages normal operation mode (<NUM>: YES). If the determination at <NUM> is that the thresholds for warm operation have not been met, the method <NUM> proceeds to determine whether thresholds for exiting LEON mode have been met (<NUM>: NO).

At <NUM>, the controller <NUM> determines whether to exit LEON mode based on an evaluation of current operating parameters indicative of a status of the system <NUM> during LEON mode. For example, if the estimated SONOx cumulatively (i.e., since the system <NUM> started or another predefined operating period) exceeds a LEON exit threshold, then the controller determines to exit LEON mode at <NUM> and to engage TM mode at <NUM> (<NUM>: YES). Alternatively, if the amount of estimated SONOx does not exceed the relevant threshold, the method <NUM> returns to <NUM> (<NUM>: NO) and continues LEON mode. Here, the amount of estimated SONOx may be based on a SONOx sensor (if the sensor is active), on a EONOx sensor, and/or on a lookup table of EONOx values based on engine <NUM> operation. In another example, if the amount of soot deposits that have accumulated on the DPF <NUM> exceed a LEON exit threshold, then the controller determines to exit LEON mode at <NUM> and to engage TM mode at <NUM> (<NUM>: YES). Alternatively, if the amount of soot deposits on the DPF <NUM> do not exceed the relevant threshold, the method <NUM> returns to <NUM> (<NUM>: NO) and continues LEON mode. As such, the method <NUM> cycles through steps <NUM>-<NUM> until either <NUM> or <NUM> are YES.

At <NUM>, the controller <NUM> engages TM mode by commanding one or more components of the system <NUM> in order to direct a greater amount of fuel energy to the aftertreatment system <NUM> by overfueling the engine through adding a restriction on the exhaust by overclosing the VG turbo (or by closing an exhaust throttle valve on a non VG turbo). The method <NUM> then proceeds to <NUM>, where the controller <NUM> determines if warm-operation thresholds have been met. This determination is similar to those determinations made at <NUM> and <NUM> in that if the warm-operation thresholds are met, the method <NUM> proceeds to <NUM> and engages normal operation mode (<NUM>: YES). If the warm-operation thresholds are not met, the method <NUM> returns to <NUM> and continues TM mode, thereby continuing in TM mode until the warm-operation thresholds are met. At no point in method <NUM> does the controller <NUM> disengage TM mode and engage LEON mode (i.e., the path from LEON mode to TM is a one-way street).

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

The term "coupled" and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using one or more separate intervening members, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If "coupled" or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of "coupled" provided above is modified by the plain language meaning of the additional term (e.g., "directly coupled" means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of "coupled" provided above. Such coupling may be mechanical, electrical, or fluidic. For example, circuit A communicably "coupled" to circuit B may signify that the circuit A communicates directly with circuit B (i.e., no intermediary) or communicates indirectly with circuit B (e.g., through one or more intermediaries).

While various circuits with particular functionality are shown in <FIG>, it should be understood that the controller <NUM> may include any number of circuits for completing the functions described herein. For example, the activities and functionalities of the initiator circuit <NUM>, the LEON exit circuit <NUM>, and the TM exit circuit <NUM> may be combined in multiple circuits or as a single circuit. Additional circuits with additional functionality may also be included. Further, the controller <NUM> may further control other activity beyond the scope of the present disclosure.

As mentioned above and in one configuration, the "circuits" may be implemented in machine-readable medium for execution by various types of processors, such as the processor <NUM> of <FIG>. Executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the circuit and achieve the stated purpose for the circuit. Indeed, a circuit of computer readable program code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within circuits, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.

While the term "processor" is briefly defined above, the term "processor" and "processing circuit" are meant to be broadly interpreted. In this regard and as mentioned above, the "processor" may 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 structured to execute instructions provided by memory. The one or more processors may take the form of a single core processor, multicore processor (e.g., a dual core processor, triple core processor, quad core processor, etc.), microprocessor, etc. In some embodiments, the one or more processors may be external to the apparatus, for example the one or more processors may be a remote processor (e.g., a cloud based processor). Alternatively or additionally, the one or more processors may be internal and/or local to the apparatus. In this regard, a given circuit or components thereof may be disposed locally (e.g., as part of a local server, a local computing system, etc.) or remotely (e.g., as part of a remote server such as a cloud based server). To that end, a "circuit" as described herein may include components that are distributed across one or more locations.

Claim 1:
A method, comprising:
initiating a low engine-out NOx (LEON) mode by controlling a component of a vehicle having an aftertreatment system (<NUM>) to decrease an instantaneous engine-out NOx (EONOx) amount;
comparing a temperature of the aftertreatment system during the LEON mode to a warm-operation threshold temperature;
responsive to determining that the temperature of the aftertreatment system exceeds the warm-operation threshold temperature, disengaging the LEON mode;
responsive to determining that the temperature of the aftertreatment system is below the warm-up operation threshold temperature, comparing information indicative of an operating status of the vehicle to a LEON exit threshold, wherein the information indicative of the operating status of the vehicle during the LEON mode comprises an accumulated amount of EONOx and the LEON exit threshold comprises an accumulated LEON EONOx threshold; and
disengaging the LEON mode responsive to determining that the information indicative of the operating status of the vehicle during the LEON mode exceeds the LEON exit threshold.