CN118234928A

CN118234928A - System and method for controlling operation of an exhaust treatment device

Info

Publication number: CN118234928A
Application number: CN202280075000.0A
Authority: CN
Inventors: A·J·伊格; M·B·雷蒙德; S·克里希纳坎坦
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2021-11-23
Filing date: 2022-11-22
Publication date: 2024-06-21
Also published as: GB2613024A; GB202116826D0; WO2023097198A1

Abstract

A method for controlling operation of a Selective Catalytic Reduction (SCR) module of an engine system includes: a determination is made as to whether fuel for combustion in an engine of an engine system includes a high sulfur content prior to a time-initiated cleaning event of the SCR module to purge sulfur accumulation in the SCR module. If a fuel having a high sulfur content is determined, the method further includes activating a mode of the engine to increase a temperature of exhaust gas entering the SCR module to assist in conversion of nitrogen oxides (NOx) in the exhaust gas at the SCR module such that a rate of reduction of conversion efficiency is reduced and allowing the SCR module to reach a time-initiated cleaning event while maintaining conversion efficiency at least equal to or above an efficiency threshold.

Description

System and method for controlling operation of an exhaust treatment device

Technical Field

The present invention relates to the field of exhaust gas treatment. More specifically, the present invention relates to controlling operation of an exhaust gas treatment device, such as a Selective Catalytic Reduction (SCR) module.

Background

Exhaust treatment devices typically include a plurality of modules for treating the exhaust. For example, the exhaust treatment device may include one or more of a Diesel Oxidation Catalyst (DOC) module, a Diesel Particulate Filter (DPF) module, and a Selective Catalytic Reduction (SCR) module. The modules may be arranged in series such that exhaust gas may flow through each of them for treatment. The DOC module may cause oxidation of exhaust constituents; the DPF module may filter soot from the exhaust to prevent the soot from being released into the atmosphere; and the SCR module may subject NOx (nitrogen oxides) present in the exhaust gas to a chemical reaction with ammonia to produce nitrogen and water.

The performance or efficiency of each of these modules may decrease with use. For example, the efficiency of an SCR module may be affected by sulfur accumulation on the SCR module. If high sulfur fuels are used, the accumulation of sulfur on the SCR module may be even faster and may result in the deactivation of the SCR module. Typically, such accumulation may be removed by an SCR cleaning process that involves increasing the temperature of the SCR module. As one example, unburned fuel may be introduced upstream of the DOC module such that the fuel may be oxidized in the DOC. In so doing, the temperature of the exhaust gas exiting the DOC module and entering the SCR module may rise, and an efficient reaction of NOx may occur at the SCR module to produce nitrogen and water. In the case of high sulfur fuels, the need to clean the SCR module may be much greater than when using conventional (e.g., low sulfur) fuels.

U.S. patent 9,988,999 discloses a system and method for regenerating an aftertreatment device or component. The disclosed methods or systems employ one or more regeneration modes of operation in which at least one aftertreatment device is regenerated by obtaining a target condition of the exhaust gas. The regeneration operating modes may include a combustion phase retard operating mode, a selected cylinder firing operating mode, an intake air flow rate reducing operating mode, an engine output increasing operating mode, an exhaust heating operating mode, and a hydrocarbon dosing operating mode.

Disclosure of Invention

In one aspect, the present disclosure is directed to a method for controlling operation of a Selective Catalytic Reduction (SCR) module of an engine system. The method includes determining whether fuel for combustion in an engine of an engine system includes a high sulfur content prior to a time-initiated cleaning event of the SCR module that purges sulfur accumulation in the SCR module. If a fuel having a high sulfur content is determined, the method further includes activating a mode of the engine to increase a temperature of exhaust gas entering the SCR module using the controller to assist in conversion of nitrogen oxides (NOx) in the exhaust gas at the SCR module such that a rate of decrease of the conversion efficiency is reduced and the SCR module is allowed to reach the time-initiated cleaning event, wherein the conversion efficiency is maintained at least equal to or above an efficiency threshold.

In another aspect, the present disclosure is directed to an engine system. The engine system includes an engine, a Selective Catalytic Reduction (SCR) module for treating exhaust gas released from the engine, and a system for controlling operation of the Selective Catalytic Reduction (SCR) module. The system includes a controller, wherein the controller is configured to detect whether fuel for combustion in the engine includes a high sulfur content prior to a time-initiated cleaning event of the SCR module to clear sulfur accumulation in the SCR module. When a fuel having a high sulfur content is detected, the controller is configured to activate a mode of the engine to increase a temperature of exhaust gas entering the SCR module to assist in conversion of nitrogen oxides (NOx) in the exhaust gas at the SCR module such that a rate of decrease in efficiency of the conversion is reduced and the SCR module is allowed to reach the time-initiated cleaning event, wherein the efficiency of the conversion is maintained at least equal to or above an efficiency threshold.

Machines such as large trucks, off-road trucks, dozers, excavators, tracked vehicles, and the like typically include an engine that may be powered, for example, by combusting fuel (e.g., diesel fuel). The fuel used in the machine may be of low quality and may have a high sulfur content due to various factors such as the region in which the machine is operating. Fuels with high sulfur content can significantly impact the operating life and operational life of aftertreatment devices (e.g., SCR modules) associated with the engine of the machine.

Drawings

FIG. 1 is a schematic illustration of an exemplary engine system according to an embodiment of the present disclosure;

FIG. 2 illustrates an exemplary method for controlling operation of a Selective Catalytic Reduction (SCR) module of an engine system according to an embodiment of the present invention; and

Fig. 3-6 are trend graphs of efficiency data associated with the efficiency of an SCR module in various situations, according to an embodiment of the invention.

Detailed Description

Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. In general, corresponding reference numerals may be used throughout the drawings to refer to the same or corresponding parts, e.g., 1', 1", 101 and 201 may refer to one or more equivalent components used in the same and/or different depicted embodiments.

Referring to FIG. 1, an engine system 100 is shown. The engine system 100 may include an engine 104 (e.g., an internal combustion engine) and an aftertreatment system 108 for the engine 104. The engine system 100 may be employed in machines such as, for example, articulated trucks, off-road trucks, dozers, excavators, tracked vehicles, loaders, and the like. Engine system 100 may also be applied to stationary machines, such as generator sets that may be used in homes and businesses. The engine 104 may include one or more cylinders (not shown) within which fuel may be supplied for combustion. The fuel may include, but is not limited to, diesel fuel, any derivative of diesel fuel, or any other combustible fuel that may include sulfur content. The fuel may be combusted when received into cylinders of the engine 104 to produce power. Once the fuel is combusted, the remaining components of the combustion of the fuel may be released as exhaust into the aftertreatment system 108.

The aftertreatment system 108 includes one or more aftertreatment devices 112 to treat the exhaust. The aftertreatment device 112 may include a Diesel Oxidation Catalyst (DOC) module 116, a Diesel Particulate Filter (DPF) module 120, and a Selective Catalytic Reduction (SCR) module 124. According to an exemplary embodiment, the exhaust may flow through each of the DOC module 116, the DPF module 120, and the SCR module 124 in an exemplary order of the aftertreatment device 112, as listed herein. In this way, exhaust gas released from the engine 104 may be treated before being released into the atmosphere 128. As one example, the DOC module 116 may oxidize certain constituents of the exhaust; the DPF module 120 may filter soot from the exhaust gas to prevent the soot from being released into the atmosphere 128; and SCR module 124 may subject nitrogen oxides (i.e., NOx) present in the exhaust gas to conversion or chemical reaction with ammonia to produce nitrogen and water. The ammonia may be held in an ammonia tank 132 and injected at the SCR module 124 by an ammonia injector 136. Those skilled in the art will readily appreciate that aspects of the present invention are applicable to a wide range of exhaust treatment devices, and that they are not limited to the examples described herein, which are provided merely to assist the reader in understanding one exemplary context of the present invention.

The performance of each aftertreatment device 112 may degrade over time and use. For example, the performance or efficiency of the SCR module 124 may be affected by sulfur accumulation on the SCR module 124. If high sulfur fuel is used, sulfur accumulation on the SCR module 124 may be relatively rapid and the efficiency of the SCR module 124 may be correspondingly reduced.

With respect to determining the efficiency of the SCR module 124, in one example, the engine system 100 may include a pair of NOx sensors. One NOx sensor (e.g., first NOx sensor 140) may be located upstream of the SCR module 124, while another NOx sensor (e.g., second NOx sensor 144) may be located downstream of the SCR module 124. An indication of the efficiency of the SCR module 124 may be derived from the pair of NOx sensors 140, 144. For example, the difference between the NOx values sensed by NOx sensors 140, 144 at any given point may be indicative of the efficiency of SCR module 124, or may be a derivative of the NOx conversion efficiency at SCR module 124. For ease of understanding and reference, this conversion efficiency may be referred to hereinafter as "efficiency data".

Further, sulfur accumulated on the SCR module 124 may be removed by an SCR cleaning process or SCR cleaning event to improve efficiency data. During operation of the engine 104, a plurality of such SCR cleaning events may be performed, for example, at regular intervals. For the purposes of the present invention, cleaning events that are implemented at regular time intervals may be referred to as time-initiated cleaning events. One or more aspects of the present invention also discuss another type of cleaning event, where such cleaning event may be implemented based on reduced efficiency data may be referred to as a threshold-initiated cleaning event, i.e., where the cleaning event is implemented when the efficiency data falls below a first predefined efficiency threshold.

According to one aspect of the invention, the SCR cleaning event involves increasing the temperature of the SCR module 124 to cause combustion and purge sulfur accumulation from the SCR module 124. To this end, the temperature of the exhaust gas entering the SCR module 124 may be increased by one or more methods. The first method may include supplying and introducing fuel (i.e., unburned fuel) (e.g., the same fuel used for combustion and power generation in the engine 104) upstream of the DOC module 116 to oxidize at the DOC module 116. In doing so, the temperature of the exhaust exiting or exiting the DOC module 116 and then entering the SCR module 124 may increase and the temperature at the SCR module 124 may increase. The second method may include injecting fuel (i.e., unburned fuel) into one or more cylinders of the engine 104 during non-combustion of the engine 104 such that the injected fuel releases the cylinders of the engine 104 unburned for combustion and oxidation at the DOC module 116. In doing so, the temperature of the exhaust exiting or exiting the DOC module 116 and then entering the SCR module 124 may increase and thus the temperature at the SCR module 124 may increase.

In accordance with one aspect of the present invention, a system and method for controlling the operation of an SCR module is further discussed below. The system is represented and/or referred to as system 148. The method may be performed by the system 148 and will be discussed later by way of the flowchart 200 provided in fig. 2. The system 148 includes a controller 152 communicatively coupled to the engine 104 to control various aspects of the operation of the engine 104. The controller 152 may also be communicatively coupled to one or more modules (e.g., the SCR module 124) and the NOx sensors 140, 144. Additionally or alternatively, the controller 152 may also be communicatively coupled to the ammonia injector 136 and a device (e.g., an ammonia mass sensor 156) that may provide an indication of the mass of ammonia in the ammonia tank 132. The controller 152 may be configured to execute a set of instructions based on which the method may be performed. In some embodiments, the method may be in operation as long as the engine 104 is active or in operation. Alternatively, if an operator of engine system 100 wishes to do so, the method may be moved or switched to an inactive state while engine 104 is operating.

The controller 152 may be communicatively coupled to or may be the same one as an Electronic Control Module (ECM) of the engine system. Alternatively, the controller 152 may be configured as a stand-alone entity. Further, the controller 152 may be a microprocessor-based device, and/or may be conceived as an application specific integrated circuit or other logic device that provides the controller functionality, and such devices are known to those of ordinary skill in the art. In one example, the controller 152 may include or represent one or more controllers having processing units configured individually or in aggregate to process various data (or inputs or commands). In some embodiments, data transfer between the controller and various other devices (e.g., SCR module 124 and NOx sensors 140, 144) may be facilitated wirelessly or by a standardized CAN bus protocol. Further, the controller 152 may be optimally adapted to be housed within certain panels or portions of the engine system 100 from which the controller 152 may remain accessible for use, maintenance, calibration, and repair.

The processing units of the controller 152 for converting and/or processing various inputs, commands, signals, etc. may include, but are not limited to, an X86 processor, a Reduced Instruction Set Computing (RISC) processor, an Application Specific Integrated Circuit (ASIC) processor, a Complex Instruction Set Computing (CISC) processor, an Advanced RISC Machine (ARM) processor, or any other processor.

Examples of memory configured within the controller 152 may include a Hard Disk Drive (HDD) and a Secure Digital (SD) card. Further, such memory may include non-volatile/volatile memory units, such as Random Access Memory (RAM)/Read Only Memory (ROM), which may include associated input and output buses. The memory may be configured to store various other instruction sets for various other functions of the engine system, along with the instruction sets discussed above.

Industrial applicability

Referring to fig. 2, a flowchart 200 is discussed. Fig. 3-6 are also discussed in connection with the discussion related to flowchart 200. The flowchart 200 includes a number of steps.

In a first step 210, the controller 152 may receive efficiency data associated with the SCR module 124. In some embodiments, the controller 152 itself may calculate the efficiency data by using and comparing the NOx values obtained from the NOx sensors 140, 144. For example, the greater the difference between the values of the NOx sensors 140, 144, the better or higher the conversion of NOx in the exhaust gas at the SCR module 124, and correspondingly, the better or higher the efficiency data. While not limited, in operation, efficiency data may be continuously calculated and/or generated. In some embodiments, the efficiency data may be converted to a percentage or an appropriate value to be output and understood by one or more operators of the machine in which the engine system 100 may be employed.

At step 220, the controller 152 may detect whether there is any reduction or decrease in the efficiency data. More specifically, the controller 152 may detect whether any reduction in efficiency data (e.g., caused by one or more of sulfur accumulation, high sulfur fuel, prolonged use, etc.) causes the efficiency data to drop below the first predefined efficiency threshold 160 (see fig. 3-6).

In the event that the controller 152 determines that the efficiency data does not fall below the first predefined efficiency threshold 160, the method moves to step 230 where the controller 152 may determine whether a time interval T has elapsed since any previous SCR cleaning event (e.g., a time-initiated cleaning event) or since the initiation of the engine 104. In case the time interval T has not elapsed, the method returns to step 210.

In the event that the time interval T has elapsed and/or has elapsed, the method moves to step 240 where the controller 152 may implement a time-initiated SCR cleaning event. For example, a time-initiated SCR cleaning event may occur every 60 hours. In other words, the time interval T may be exemplarily equal to 60 hours. Once the time-initiated cleaning event has ended, the method returns to step 210.

As described above, the above-described operation relates to the situation when the SCR module 124 is operated as desired in conventional operation, such as using conventional (low sulfur) fuel. Notably, in such cases, the method may remain within the bounds of flowchart 200, as defined by dashed boundary 244.

FIG. 3 shows an example trend graph 300 of efficiency data (e.g., in percent) versus time (e.g., in hours) when the method operates within the dashed boundary 244 of the flowchart 200 of FIG. 2. In the example trend graph 300 of fig. 3, as shown, the efficiency data does not fall below the first predefined efficiency threshold 160. As can be noted, trend graph 300 of fig. 3 covers a period of time that includes two SCR cleaning events (e.g., two time-initiated cleaning events indicated by a period of time between time B and time C and a period of time between time D and time E, respectively), which occurs at 60 hour intervals, for example. Thus, for trend graph 300 of efficiency data in fig. 3, time interval T is illustratively 60 hours.

Specifically, in FIG. 3, engine operation begins at time A; the first time initiated cleaning event begins at time B (i.e., 60 hours after engine operation, e.g., from time a); the first initiated cleaning event ends at time C; the second time initiated cleaning event begins at time D (i.e., 60 hours after engine operation, e.g., from time C); and the second initiated cleaning event ends at time E. After each time-initiated cleaning event, it may be noted that the efficiency data generally returns to that seen after (e.g., immediately after) any previous SCR cleaning event.

In the case of high sulfur fuel, the efficiency data may decrease rapidly such that conventional cleaning events to clean the SCR module 124 at predetermined time intervals T may be insufficient. Referring again to fig. 2, at step 220, and prior to the next time initiated cleaning event, if the controller 152 determines that the efficiency data falls below the first predefined efficiency threshold 160, the method may move to step 250, where the controller 152 may illustratively check whether ammonia configured to be injected into the SCR module 124 is too dilute (e.g., by reading a value from the ammonia mass sensor 156) and/or whether the ammonia injector 136 is clogged. If such a check is affirmative (i.e., if the controller 152 determines that the ammonia is indeed too dilute and/or the ammonia injector 136 is blocked), the controller 152 may infer that the low, declining efficiency data is due to one or more of a low quality of ammonia or an ammonia injector operating failure, rather than infer that the fuel has a high sulfur content, and thus the method returns to step 210.

If the above check is negative (i.e., if the controller 152 determines that ammonia is neither too diluted nor blocked by the ammonia injector 136), the method moves to step 260 where the controller 152 effects a threshold initiated cleaning event of the SCR module 124. A threshold initiated cleaning event may occur regardless of the internal time T and/or the time elapsed since any previous SCR cleaning event or start of the engine 104. Further, it may be noted that the threshold-initiated cleaning event may be the same (both functionally and operationally) as the time-initiated cleaning event.

After starting the threshold initiated cleaning event at step 260, the controller 152 may check at step 270 whether the efficiency data has recovered beyond a second predefined efficiency threshold 164 (see fig. 4). The second predefined efficiency threshold 164 may be higher than the first predefined efficiency threshold 160. If the efficiency data does not exceed the second predefined efficiency threshold 164, the reason for the inability to infer the inefficiency data is due to the use of high sulfur fuel, but the controller 152 may infer that the inefficiency data may be caused by other factors related to the operation of the aftertreatment system 108 (e.g., a faulty SCR module, etc.), and thus the method returns to step 210.

In the event that the controller 152 detects that the efficiency data obtained by the threshold-initiated cleaning event exceeds the second predefined efficiency threshold 164, the method moves to step 280 where the controller 152 may detect or determine that the fuel for combustion has a high sulfur content and, in response, the controller 152 may output a high sulfur fuel warning or alarm. In some embodiments, the alert or alarm may be output by an output device (not shown), such as a display device, a lighting device, an audio alert device, or the like. For example, the high sulfur warning may include one or more of the following: visual and/or audio alerts are output to operators, service engineers, fleet operators, or any stakeholders of the engine system 100 to indicate to them that the fuel has a high sulfur content.

At step 290, the controller 152 may activate a mode, such as a thermal management mode, in response to determining that the fuel has a high sulfur content and/or in response to a high sulfur warning or alarm. This mode helps to increase the temperature of the exhaust gas entering the SCR module 124 to aid in the conversion of nitrogen oxides (NOx) in the exhaust gas at the SCR module 124, such that the rate of decrease of conversion efficiency (or the rate of decrease of efficiency data) (due to the high sulfur content in the fuel) decreases and allows the SCR module 124 to reach the next time-initiated cleaning event. For example, the SCR module 124 may be allowed to reach a next time-initiated cleaning event in which the conversion efficiency (or efficiency data) is maintained at least equal to or above an efficiency threshold (e.g., a primary efficiency threshold 168, see fig. 3-6). Although not limited, the primary efficiency threshold 168 may be a predetermined value of efficiency and may be equal to the first predefined efficiency threshold 160.

In some embodiments, the activation mode includes changing one or more operating parameters of the engine 104. For example, the operating parameter may include a load associated with the engine 104, and changing the operating parameter may include increasing the load associated with the engine 104. The increase in load on the engine 104 may include connecting one or more parasitic loads (e.g., electrical loads, hydraulic loads, etc.) to the engine 104. In some embodiments, the operating parameters may include injecting fuel into the engine 104 to power the engine 104, and changing the parameters may include increasing the injection of fuel into the engine 104. Such changes in parameters increase the temperature of the exhaust gas exiting the engine 104 and entering the aftertreatment device 112.

Referring to fig. 4, a graph or trend 400 of efficiency data (e.g., in percent) versus time (e.g., in hours) is shown for the case of using a high sulfur fuel. Operation of engine 104 begins at time a. The efficiency data drops rapidly such that the efficiency data drops below the first predefined efficiency threshold 160 at time F. I.e. before the time interval T (e.g. before 60 hours of engine operation) has elapsed. As a result, the controller 152 (step 260 in fig. 2) triggers and implements a threshold-initiated cleaning event. In fig. 4, a threshold initiated cleaning event (which occurs between time F and time G) results in the efficiency data returning to that seen at the beginning of the operating session of the engine 104 (e.g., comparing time a and time G in fig. 4), and in the process may also result in the efficiency data exceeding a second predefined efficiency threshold 164 (determined by the controller 152 at step 270 of fig. 2). At time G, or once the efficiency data exceeds the second predefined efficiency threshold 164, the controller 152 determines that the fuel for combustion in the engine 104 has a high sulfur content and outputs a high sulfur fuel warning (i.e., step 280 in fig. 2). Further, the controller 152 may stop the threshold initiated cleaning event at time G or once the efficiency data exceeds the second predefined efficiency threshold 164.

Once the controller 152 stops the threshold initiated cleaning event at time G, the controller 152 may activate the mode (i.e., step 290 of fig. 2). Assuming that the mode may include taking steps to increase the temperature of the SCR module 124, the mode may in turn cause a decrease in the rate of decrease of the efficiency data. Thus, in trend graph 400 of FIG. 4, the gradient of the efficiency data graph between time G and time B' is less than the gradient of the efficiency data graph between time A and time F. As described above, this mode may allow the SCR module 124 to reach a time-initiated cleaning event (i.e., the next time-initiated cleaning event represented by a plot of efficiency data between times B). In the event that the conversion efficiency remains at least equal to or above an efficiency threshold (e.g., a primary efficiency threshold 168),

Referring to fig. 5, in some embodiments, the controller 150 may also deactivate this mode (e.g., to save fuel) during a cleaning event that is initiated from operation to the next time. This deactivation may be performed by the controller 152 if the efficiency of the conversion or if the efficiency data remains above the secondary efficiency threshold 172 for a predetermined duration. As may be noted from fig. 5, the secondary efficiency threshold 172 is represented by a dashed line in fig. 5, and may be, for example, higher than the primary efficiency threshold 168. In some embodiments, the dashed line representing the secondary efficiency threshold 172 may acquire the trend graph 500 of efficiency data of fig. 5 indicating at least about a middle (or relatively higher than middle) position between the lines of the primary efficiency threshold 168 and the second predefined efficiency threshold 164.

An exemplary manner of determining the predetermined duration and the secondary efficiency threshold 172 will now be discussed. In the trend graph 500 of efficiency data shown in fig. 5, the controller 152 may determine a graph of decreasing efficiency data for any given point on the graph of efficiency data between time a and time C (i.e., when neither mode nor SCR cleaning event is active) may be similar to (and thus parallel to) the graph between time a and time F. With the stored plot of the drop efficiency data, the controller 152 may apply (e.g., by superimposing) a plot of the drop efficiency data corresponding to a plurality of points along the plot from time G to time I. As one example, the controller 152 may apply a curve of decreasing efficiency data corresponding to time I and may determine that the curve of decreasing efficiency data from time I will remain above the primary efficiency threshold 168 or will meet the primary efficiency threshold 168, but will refrain from (e.g., deterministically) decreasing below the primary efficiency threshold 168 before the next time-initiated cleaning event begins. Accordingly, the controller 152 may infer that the efficiency data of the SCR module 124 does not drop or fall below the primary efficiency threshold 168 even if the mode is deactivated at time I or any time from then until time B "(i.e., before the SCR module 124 reaches the next time-initiated cleaning event). Thus, the controller 152 may deactivate the mode at time I, or at any time between time I and time B ", at the remainder of the corresponding interval. In some embodiments, the controller 152 may determine the predetermined duration as the time span between time G and time I, and determine the secondary efficiency threshold 172 as the efficiency percentage corresponding to time I. The controller 152 may also similarly determine a predetermined duration and secondary efficiency threshold for one or more subsequent operating intervals of the SCR module 124.

In the trend graph 500 of efficiency data of fig. 5, the curve of efficiency data moves from time I to time B ", where time B" indicates a point on the primary efficiency threshold 168. In addition, time B "also indicates the start of the next time-initiated cleaning event, i.e., time B" to time C represent the next time-initiated cleaning event. In some embodiments, this mode may be disabled only when at least 80% of the interval (e.g., 80% of the 60 hour period) ends.

In some embodiments, the controller 152 may also deactivate the mode if the conversion efficiency (i.e., efficiency data) falls below the primary efficiency threshold 168, or if the rate of fall of the conversion efficiency after the deactivated mode exceeds a predetermined rate threshold.

Fig. 6 shows a graph or trend 600 of efficiency data versus time for the case of using high sulfur fuel. This trend graph 600 of efficiency data in fig. 6 shows another scenario. In the trend graph 600 of efficiency data, operation of the engine 104 begins at time A. The efficiency data drops rapidly such that before the time interval T elapses (e.g., before the engine is run for 60 hours), the efficiency data drops below the first predefined efficiency threshold 160. As a result, the controller 152 triggers and implements a threshold initiated cleaning event (i.e., step 260 in fig. 2). As discussed in fig. 4 and 5, in fig. 6, the threshold-initiated cleaning event (which occurs between time F and time G) results in the efficiency data returning to that seen at the beginning of the engine's operating session (e.g., comparing time a and time G), and in the process, may also result in the efficiency data exceeding a second predefined efficiency threshold 164 (determined by the controller 152 at step 270 of fig. 2). At time G, the controller 152 determines the high sulfur fuel and outputs a high sulfur fuel warning (i.e., step 280 in fig. 2). Further, the controller 152 may stop the threshold initiated cleaning event at time G or once the efficiency data exceeds the second predefined efficiency threshold 164.

Once the controller 152 stops the threshold initiated cleaning event, the controller 152 may activate the mode (i.e., step 290 of fig. 2). Assuming that the mode may include taking steps to increase the temperature of the SCR module 124, the mode may in turn cause a decrease in the rate of decrease of the efficiency data. Thus, the curve gradient between time G and time H is less than the curve gradient between time a and time F. While the difference in gradients may reduce or decrease the rate of decrease of the efficiency data, in some embodiments, the controller 152 may extrapolate the curve between times G. And time H, and determine whether the rate of decline in the efficiency data is sufficient in a manner that allows the SCR module 124 to reach the next time-initiated cleaning event. In the case of the exemplary trend graph 600 in fig. 6, the controller 152 may extrapolate and determine that the curve between time G and time H at time J may intersect or intersect the primary efficiency threshold 168, and thus may potentially drop or fall back below the primary efficiency threshold 168 before the completion of time interval T (either before the exemplary 60 hour period or without reaching the next time-initiated cleaning event). In such cases, the controller 152 may determine that the mode may not be able to allow the SCR module 124 to reach the next time-initiated cleaning event in its operating mode without maintaining the efficiency data at least equal to or above the primary efficiency threshold 168.

In response to such conditions, the controller 152 may further alter the operating parameters of the engine 104. For example, the controller 152 may also add or connect additional load to the engine 104 and/or also add injection of fuel into the engine 104 in order to increase (e.g., proportionally) the temperature of the exhaust exiting the engine 104. In doing so, the controller 152 may help further increase the temperature of the SCR module 124 such that more NOx at the SCR module 124 undergoes conversion, and thereby increase the efficiency data to a degree that allows the SCR module 124 to reach this next time-initiated cleaning event (see the curve between time B' "and time C), where the efficiency of conversion is maintained at least equal to or above the primary efficiency threshold 168.

Further, in some embodiments, the temperature at the SCR module 124 during the period when the mode is active may be lower than the temperature at the SCR module during the period when the time-initiated cleaning event or the threshold-initiated cleaning event is active or ongoing. For example, the temperature at the SCR module 124 during the period when the mode is active may be between 275 ℃ and 325 ℃, and the temperature at the SCR module 124 during the period when a time-initiated cleaning event or a threshold-initiated cleaning event is ongoing may be between 450 ℃ and 500 ℃.

With the above-described method, even when fuel having a high sulfur content is used to power the engine 104, the efficiency data of the SCR module 124 may be maintained above a threshold (e.g., above the main efficiency threshold 168) for a substantial period of time, thereby improving the operation of the SCR module 124 and its post-processing performance (i.e., converting NOx in the exhaust gas to nitrogen and water). As described above, the system and method prevent overall performance degradation of the aftertreatment system and, first, provide an indication to the operator of fuels having a high sulfur content, and, second, provide a mechanism by which the fuel may be used up until a higher quality fuel (e.g., a fuel having a relatively low sulfur content) is available. Further, the systems and methods as discussed herein allow the SCR module 124 to reach the next opportunity to clean itself (e.g., via hydrocarbon dosing) without significantly affecting its conversion efficiency.

It will be apparent to those skilled in the art that various modifications and variations can be made to the exhaust system of the present invention without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the systems disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims and their equivalents.

Claims

1. A method for controlling operation of a selective catalytic reduction module of an engine system, the method comprising:

Prior to a time-initiated cleaning event of the selective catalytic reduction module to purge sulfur accumulation in the selective catalytic reduction module,

Determining whether fuel for combustion in an engine of the engine system includes a high sulfur content; and

If a fuel having a high sulfur content is determined, a controller is used to activate a mode of the engine to increase a temperature of exhaust gas entering the selective catalytic reduction module to assist in conversion of nitrogen oxides in the exhaust gas at the selective catalytic reduction module such that a rate of decrease of the conversion efficiency is reduced and the selective catalytic reduction module is allowed to reach the time-initiated clean event, wherein the conversion efficiency is maintained at least equal to or above an efficiency threshold.

2. The method of claim 1, wherein activating the mode comprises changing one or more operating parameters of the engine, wherein the one or more operating parameters comprise a load associated with the engine, and wherein changing the one or more operating parameters comprises increasing the load associated with the engine.

3. The method of claim 1, wherein activating the mode comprises changing one or more operating parameters of the engine, wherein the one or more operating parameters comprise injecting the fuel into the engine to power the engine, and changing the one or more operating parameters comprises increasing the injection of the fuel into the engine.

4. The method of claim 1, wherein determining that the fuel has a high sulfur content comprises:

Detecting, by the controller, that the conversion efficiency of nitrogen oxides falls below a first predefined efficiency threshold;

Implementing, by the controller, a threshold initiated cleaning event of the selective catalytic reduction module; and

If the conversion efficiency obtained by the threshold initiated cleaning event exceeds a second predefined efficiency threshold, then the fuel is determined by the controller to have a high sulfur content.

5. The method of claim 4, wherein the second predefined efficiency threshold is higher than the first predefined efficiency threshold and the threshold initiated cleaning event is the same as the time initiated cleaning event.

6. The method of claim 1, wherein the efficiency threshold is a primary efficiency threshold, the method further comprising disabling the mode by the controller if the efficiency of the transition remains above a secondary efficiency threshold for a predetermined duration.

7. The method of claim 6, wherein the secondary efficiency threshold is higher than the primary efficiency threshold.

8. The method of claim 6, further comprising disabling the mode by the controller if the efficiency of the transition falls below the primary efficiency threshold or a rate of fall of the efficiency of the transition after disabling the mode exceeds a predetermined rate threshold.

9. The method of claim 1, wherein during the period when the mode is active, the temperature at the selective catalytic reduction module is lower than the temperature at the selective catalytic reduction module during the period when the time-initiated cleaning event is ongoing.

10. The method of claim 1, wherein one or more of the time-initiated cleaning event and the threshold-initiated cleaning event comprises one or more of:

supplying fuel upstream of a diesel oxidation catalyst module for oxidation at the diesel oxidation catalyst module to increase the temperature of the exhaust gas exiting the diesel oxidation catalyst module and entering the selective catalytic reduction module; and

The fuel is injected into one or more cylinders of the engine during non-combustion of the engine such that the injected fuel is released from the engine to combust and oxidize at the diesel oxidation catalyst module, thereby increasing the temperature of the exhaust gas exiting the diesel oxidation catalyst module and entering the selective catalytic reduction module.

11. An engine system, comprising:

an engine;

A selective catalytic reduction module for treating exhaust gas released from the engine;

A system for controlling operation of the selective catalytic reduction module, the system comprising:

A controller, wherein, prior to a time-initiated cleaning event of the selective catalytic reduction module to purge sulfur accumulation in the selective catalytic reduction module, the controller is configured to:

detecting whether fuel for combustion in the engine includes a high sulfur content; and

When a fuel having a high sulfur content is detected, a mode of the engine is activated to increase a temperature of the exhaust gas entering the selective catalytic reduction module to assist in conversion of nitrogen oxides in the exhaust gas at the selective catalytic reduction module such that a rate of decrease of conversion efficiency is reduced and the selective catalytic reduction module is allowed to reach the time-initiated clean event while the conversion efficiency remains at least equal to or above an efficiency threshold.

12. The engine system of claim 11, wherein to activate the mode, the controller is configured to change one or more operating parameters of the engine, wherein the one or more operating parameters include a load associated with the engine, and changing the one or more operating parameters includes increasing the load associated with the engine.

13. The engine system of claim 11, wherein to activate the mode, the controller is configured to change one or more operating parameters of the engine, wherein the one or more operating parameters include injecting the fuel into the engine to power the engine, and changing the one or more operating parameters includes increasing the injection of the fuel into the engine.

14. The engine system of claim 11, wherein to determine that the fuel has a high sulfur content, the controller is configured to:

detecting that the conversion efficiency of nitrogen oxides falls below a first predefined efficiency threshold;

A cleaning event to achieve threshold initiation of the selective catalytic reduction module; and

If the conversion efficiency obtained by the threshold initiated cleaning event exceeds a second predefined efficiency threshold, the fuel is determined to have a high sulfur content.

15. The engine system of claim 14, wherein the second predefined efficiency threshold is higher than the first predefined efficiency threshold and the threshold initiated cleaning event is the same as the time initiated cleaning event.

16. The engine system of claim 11, wherein the efficiency threshold is a primary efficiency threshold, the controller being configured to deactivate the mode if the efficiency of the transition remains above a secondary efficiency threshold for a predetermined duration.

17. The engine system of claim 16, wherein the secondary efficiency threshold is higher than the primary efficiency threshold.

18. The engine system of claim 16, wherein the controller is configured to deactivate the mode if the conversion efficiency drops below the primary efficiency threshold after deactivating the mode or a rate of drop of the conversion efficiency exceeds a predetermined rate threshold.

19. The engine system of claim 11, wherein a temperature at the selective catalytic reduction module is lower during a period in which the mode is active than during a period in which the time-initiated cleaning event is ongoing.

20. The engine system of claim 11, wherein one or more of the time-initiated cleaning event and the threshold-initiated cleaning event comprises one or more of: