Engine control for exhaust aftertreatment thermal management

Abstract

A method includes operating an engine system including a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to the plurality of cylinders, a compression brake system configured to selectively brake at least a first group of the plurality of cylinders, and an exhaust aftertreatment system including at least one catalyst. The method includes determining a condition of brake-fuel operation, and responsive to the determined action, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking for the first set of the plurality of cylinders, and operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking for the second set of the plurality of cylinders. And a second group of the plurality of cylinders receives and combusts fuel provided from respective ones of the plurality of fuel injectors.

Description

[0001] Cross-references

[0002] This application claims priority to and the benefit of U.S. Application No. 62 / 966,578, filed on January 28, 2020, which is hereby incorporated by reference in its entirety. Background Art

[0003] The present application generally relates to engine control for exhaust aftertreatment thermal management. An internal combustion engine system may utilize many exhaust aftertreatment systems including one or more catalysts to reduce emissions, including particulates, nitrogen oxides (NOx), and hydrocarbon (HC) emissions. Examples of such catalysts include selective catalytic reduction (SCR) catalysts for reducing NOx emissions, particulate filters such as diesel particulate filters (DPF) for reducing particulate emissions, and oxidation catalysts such as diesel oxidation catalysts for oxidizing HC to reduce HC emissions and providing high temperatures for downstream aftertreatment system components. In order to achieve the desired emission reduction, the aftertreatment system catalyst generally needs to reach a minimum operating temperature. The aftertreatment system catalyst may also need to reach a minimum regeneration temperature for a catalyst regeneration event, which may exceed the minimum operating temperature of the catalyst. Many methods have been proposed for exhaust thermal management to achieve a minimum operating temperature and a minimum regeneration temperature. Existing methods have many disadvantages, shortcomings, and defects. For example, conventional methods may require devices such as DOCs, variable geometry turbochargers (VGTs), and / or exhaust throttle valves (EVTs), one or more of which may not be present in certain systems. Other proposals have been made for operating the engine at idle speed and for fueling certain cylinders while applying engine braking to other cylinders. Even with these approaches, there are many problems. For example, in addition to replacing the catalyst with a blocked face, the problem of the first catalyst face being blocked remains unsolved. In addition, conventional methods tend to disrupt the desired engine operation or make the method unable to exist independently during engine mission operation (e.g., operation at rated engine speed and / or torque). There remains a large unmet need for the unique devices, methods, systems, and technologies disclosed herein.

[0004] Disclosure of Example Implementations

[0005] In order to clearly, concisely and accurately describe the exemplary embodiments of the present disclosure, the manner and process of making and using the present disclosure, and to enable the practice, manufacture and use of the present disclosure, reference will now be made to certain exemplary embodiments, including those shown in the figures, and specific language will be used to describe the present disclosure. However, it should be understood that no limitation to the scope of the present invention is thereby incurred, and the present invention includes and protects such changes, modifications and further applications of the exemplary embodiments as would occur to a person skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic diagram illustrating certain aspects of an example engine system.

[0007] Figure 2 is a flow chart illustrating certain aspects of an example control process.

[0008] Figure 3 is a flow chart illustrating certain aspects of an example control process.

[0009] Figure 4 is a flow chart illustrating certain aspects of an example control process.

[0010] Figure 5 is a flow chart illustrating certain aspects of an example control process.

[0011] Figure 6 is a graph illustrating certain aspects of an example engine system operating map. DETAILED DESCRIPTION

[0012] refer to Figure 1 , certain aspects of an example engine system 10 are shown. The engine system 10 includes an internal combustion engine 12 (also referred to herein as the engine 12), which includes an intake manifold 14, which is fluidly coupled to an outlet of a compressor 16 of a turbocharger 18 through an intake conduit 20. The compressor 16 includes a compressor inlet coupled to the intake conduit 22 for the intake conduit to receive fresh air. The compressor 16 is mechanically coupled to a turbine 26 via a drive shaft 28. The turbine 26 includes a turbine inlet, which is fluidly coupled to an exhaust manifold 30 of the engine 12 via an exhaust conduit 32. The engine system 10 may include an intake air cooler 24, which is disposed in line with the intake conduit 20 between the compressor 16 and the intake manifold 14. The engine system 10 may also include an intake throttle (IAT) 21.

[0013] In the illustrated embodiment, the engine 12 is a reciprocating piston, direct injection, compression ignition engine configured to burn diesel fuel. However, it should be understood that the engine 12 may also be provided in other forms, including one or more of port injection, spark ignition, and configured to burn other types of fuels, such as natural gas or other gaseous fuels or gasoline.

[0014] The engine 12 includes a plurality of cylinders 12a to 12f containing respective reciprocating pistons, each of which is connected to a crankshaft by a corresponding connecting rod (not shown) for reciprocating in the respective cylinders 12a to 12f in a standard manner for four-stroke engine operation. Each cylinder 12a to 12f includes a combustion chamber having appropriate intake and exhaust valves (not shown) and a fuel injector 13a to 13f. The fuel injectors 13a to 13f are configured to operate in response to signals from an electronic controller described in more detail below. The fuel injectors 13a to 13f receive fuel from a fuel source (not shown) in fluid communication therewith.

[0015] The engine 12 includes a compression brake system 15 configured to selectively brake at least a first group of the cylinders 12a to 12f. It should be understood that reference to braking a group of cylinders in conjunction with brake-fuel operation indicates braking one or more of the plurality of cylinders, but less than all of the plurality of cylinders, for example, braking three cylinders of the engine 12 in an inline six-cylinder configuration, or braking four cylinders of each of two banks of cylinders of the engine 12 in a V-16 configuration. The compression brake system 15 may include one or more compression brake actuators configured to hold open one or more exhaust valves of one or more of the cylinders 12a to 12f when activated, more specifically, so as to provide a compression brake operating mode, also referred to as an exhaust brake operating mode, such that air is pumped into and out of the respective cylinders 12a to 12f through the open valves.

[0016] like Figure 1As shown, the compression brake system 15 may include a plurality of brake actuators 15a to 15f that are individually controllable to provide compression braking of corresponding cylinders of the cylinders 12a to 12f. The compression brake system 15 may also be provided in other forms. In certain forms, the compression brake system 15 may include a brake actuator that is configured to provide compression braking for a group of cylinders 12a to 12f. For example, in a form in which the engine 12 is provided in an inline configuration, the compression brake system 15 may include a single brake actuator that is configured to provide compression braking for a group of cylinders 12a to 12f, such as cylinders 12a to 12c. Alternatively, the compression braking system 15 may include a first brake actuator configured to provide compression braking for a first group of cylinders 12a to 12f (e.g., cylinders 12a to 12c) and a second brake actuator configured to provide compression braking for a second group of cylinders 12a to 12f (e.g., cylinders 12d to 12f).

[0017] In a form where the engine 12 is provided in a V-type configuration including first and second cylinder banks, the compression brake system 15 may include a single brake actuator configured to provide compression braking for a group of cylinders in the first bank and a single brake actuator configured to provide compression braking for a group of cylinders in the second bank. Alternatively, the compression brake system 15 may include: a first brake actuator configured to provide compression braking for a first group of cylinders in the first bank; a second brake actuator configured to provide compression braking for a second group of cylinders in the first bank; a third brake actuator configured to provide compression braking for a third group of cylinders in the second bank; and a fourth brake actuator configured to provide compression braking for a fourth group of cylinders in the fourth bank.

[0018] The engine system 10 includes an EGR valve 38 disposed in line with the EGR conduit 36, with one end of the EGR valve 38 being fluidly coupled to the intake conduit 20 and the other end being fluidly coupled to the exhaust conduit 32. Figure 1 As shown by the dashed line in FIG. 8 , an EGR cooler 40 may optionally be disposed in line with the EGR conduit 36 ​​between the EGR valve 38 and the intake conduit 20 .

[0019] The engine system 10 includes an electronic control system. In the illustrated form, the electronic control system includes a controller 42, which may be provided as an electronic control unit (ECU) or an electronic control module (ECM). The electronic control system may also include additional controllers, which may be provided as additional ECU or ECM units, which communicate with each other via a communication network such as a controller area network (CAN).

[0020] The controller 42 is generally operable to control and manage aspects of the operation of the engine 12. The controller 42 includes a memory 45 and a plurality of inputs and outputs for interfacing with various sensors and systems connected to the engine 12. The controller 42 may be an electronic circuit composed of one or more components, including digital circuits, analog circuits, or both. The controller 42 may be of a software and / or firmware programmable type; a hardwired dedicated state machine; or a combination of these. In one embodiment, the controller 42 is of a programmable microcontroller solid-state integrated circuit type, including a memory 45 and one or more central processing units. The memory 45 may be composed of one or more components and may be of any volatile or non-volatile type, including solid-state types, optical media types, magnetic types, combinations of these or other arrangements. The controller 42 may include signal conditioners, signal format converters (e.g., analog-to-digital converters and digital-to-analog converters), limiters, clamps, filters, etc., as needed to perform the various control operations and regulation operations described herein.

[0021] The controller 42 may be configured to regulate and control the overall operation of the engine 12. Alternatively, the controller 42 may be configured to regulate and control a set of controlled aspects of the engine 12. The controller 42 is configured to store controller-executable instructions and execute these instructions to provide regulation and control of the engine 12. These controller-executable instructions may be configured according to one or more of the control processes described herein, as well as other control processes.

[0022] The controller 42 is configured to receive a plurality of inputs for receiving signals from various sensors or sensing systems associated with the engine system 10. For example, the engine system 10 includes an engine speed sensor 44 electrically connected to the engine speed input ES of the controller 42 via a signal path 46. The engine speed sensor 44 is operable to sense the speed of the engine 12 and generate an engine speed signal on the signal path 46 indicating the engine speed. In one embodiment, the engine speed sensor 44 is a Hall effect sensor operable to determine the engine speed. Alternatively, the engine speed sensor 44 may be any other known sensor operable as just described, including but not limited to a variable reluctance sensor, etc.

[0023] The engine system 10 may include an intake manifold temperature sensor 48 disposed in fluid communication with the intake manifold 14 of the engine 12 and electrically connected to an intake manifold temperature input (IMT) of the controller 42 via a signal path 50. The intake manifold temperature sensor 48 is operable to provide a temperature signal on the signal path 50 indicative of a temperature of charge-air flowing into the intake manifold 14, wherein the charge-air flowing into the intake manifold 14 is generally composed of fresh air supplied by the compressor 16 in combination with recirculated exhaust gas supplied by the EGR valve 38.

[0024] The engine system 10 may include an intake manifold pressure sensor 52 disposed in fluid communication with the intake manifold 14 and electrically connected to an intake manifold pressure input (IMP) of the controller 42 via a signal path 54. Alternatively, the intake manifold pressure sensor 52 may be disposed in fluid communication with the intake conduit 20. In any case, the intake manifold pressure sensor 52 is operable to generate a pressure signal on the signal path 54 indicative of the air pressure within the intake conduit 20 and the intake manifold 14.

[0025] The engine system 10 also includes an exhaust manifold pressure sensor 72, which is arranged to be in fluid communication with the exhaust manifold 30 and is electrically connected to the exhaust manifold pressure input (EMP) of the controller 42 via a signal path 72a. In other forms, the exhaust manifold pressure sensor 72 can be arranged to be in fluid communication with the exhaust conduit 32. In any case, the exhaust manifold pressure sensor 72 can have a known configuration and can be operated to generate a pressure signal indicating the pressure of the gas in the exhaust conduit 32 and the exhaust manifold 30 on the signal path 72a. In other forms, one or both of the exhaust manifold pressure sensor 72 and the exhaust manifold temperature sensor 74 may not be present in the engine system 10, and the exhaust pressure and temperature can be calculated or estimated based on other parameters. For example, in the form where the exhaust manifold pressure sensor is not present, many techniques or models can be used to calculate or estimate the exhaust manifold pressure, such as via the speed density equation or by other calculations or estimates.

[0026] The engine system 10 may include a differential pressure sensor or DP sensor 56 that is fluidly coupled at one end to the EGR conduit 36 ​​adjacent to the waste inlet of the EGR valve 38 via conduit 60 and at the other end to the EGR conduit 36 ​​adjacent to the exhaust outlet of the EGR valve 38 via conduit 58. Alternatively, the DP sensor 56 may be coupled across another flow restriction mechanism disposed in line with the EGR conduit 36. In either case, the DP sensor 56 may have a known configuration and be electrically connected to the DP input of the controller 42 via a signal path 62. The DP sensor 56 is operable to provide a differential pressure signal on the signal path 62 that is indicative of a pressure differential across the EGR valve 38 or other flow restriction mechanism disposed in line with the EGR conduit 36. Nevertheless, it should be appreciated that in other embodiments, the EGR valve 38, DP sensor 56, and associated conduits, coolers, etc. may not be present.

[0027] The controller 42 is also configured to provide a number of outputs for controlling one or more engine functions associated with the engine system 10. For example, the EGR valve 38 is electrically connected to the EGR valve output (EGRV) of the controller 42 via a signal path 64. As is known in the art, the controller 42 is operable to generate an EGR valve control signal on the signal path 64, thereby correspondingly controlling the position of the EGR valve 38 relative to the reference position in a known manner. The controller 42 is therefore operable to control the EGR valve 38 to selectively provide a recirculated exhaust gas flow from the exhaust manifold 30 to the intake manifold 14. Therefore, although the gas composition flowing along the passage 33 changes from (a) compressed air, (b) to air / fuel charge, and then (c) to exhaust gas when the EGR valve 38 is closed, this composition may also include various amounts of recirculated exhaust gas when the EGR valve 38 is open. In certain embodiments, the controller 42 may also include one or more outputs for controlling the operation of a turbocharger mechanism, such as a wastegate (if present) and a variable geometry actuator (if present) for the turbocharger 18.

[0028] The controller 42 is also configured to provide a plurality of fueling command outputs for controlling the operation of each of the fuel injectors 13a to 13f or to another number of fuel injectors present in other embodiments and versions of the engine system 10. The signal path for output FC is also provided at Figure 1 13a to 13f; however, it should be understood that the timing of the fuel injected by each injector 13a to 13f can be independently controlled by the controller 42. In addition to the timing of the fuel injection, the controller 42 can also adjust the amount of fuel injection. Generally, the amount of fuel varies with the number and duration of the injector activation pulses provided to the injectors 13a to 13f.

[0029] The controller 42 is configured to provide one or more outputs to activate and deactivate the compression brake actuators 15a to 15f or another number of compression brake actuators present in other embodiments and versions of the engine system 10. The signal paths of these outputs are Figure 1 4 and 5. However, it should be understood that the timing and activation of the actuators 15a to 15f may be independently controlled by the controller 42. In other embodiments, the compression brake actuators 15a to 15f may be actuated in groups, with each group numbering more than one. In other embodiments, a different number of compression brake actuators may be controlled by the controller 42, for example, a single actuator configured to apply engine braking to two or more cylinders.

[0030] The controller 42 is configured to coordinate control of the fuel injectors 13a to 13f (or another number of fuel injectors present) and the compression brake actuators 15a to 15f (or another number of compression brake actuators present) to provide brake-fuel (BF) operation of the engine system 10, wherein the fuel injectors associated with the first group of cylinders are controlled to provide fuel and one or more compression brakes associated with the second group of cylinders are controlled to provide compression braking such that the first group of cylinders and the second group of cylinders operate at least partially in opposition to each other. It should be appreciated that BF operation according to the present disclosure may be provided in conjunction with a variety of unique operating modes to achieve a variety of unique operating states of the engine system 10. In certain modes, the controller 42 may control the BF operation of the engine system 10 to provide elevated exhaust gas temperatures during operation while minimizing unintended effects on the performance of the engine system 10.

[0031] In certain forms and modes, in-mission BF operations may be performed while maintaining a substantially constant engine speed (e.g., maintaining a rated or predetermined engine speed + / - 2.5% or another percentage to provide acceptable performance depending on the application and mission in question). Certain such forms may provide a substantially constant engine speed while accommodating and providing for significant changes in engine load (e.g., idle loads up to rated load).

[0032] In certain forms and modes, the controller 42 may control the BF operation of the engine system 10 to provide an elevated exhaust gas temperature sufficient to regenerate a catalyst, such as the diesel particulate filter (DPF) 84 described herein or another catalyst. In certain forms and modes, the controller 42 may control the BF operation of the engine system 10 to provide an elevated exhaust gas temperature sufficient to regenerate a catalyst, such as the diesel particulate filter (DPF) 84, during vehicle idle coasting operation or during other operating conditions in low load missions.

[0033] In certain forms and modes, the controller 42 may control the BF operation of the engine system 10 to provide an elevated exhaust gas temperature sufficient to reverse the first catalyst face plugging, which would otherwise require catalyst replacement. Such elevated exhaust gas temperature may preferably be at least 360 degrees Celsius or higher, more preferably at least 380 degrees Celsius or higher, or most preferably at least 400 degrees Celsius or higher.

[0034] The engine system 10 also includes an aftertreatment system 80 that provides aftertreatment of the exhaust gas before being discharged through the conduit 94. During engine operation, the exhaust gas flows from the turbine outlet 27 through the exhaust conduit 34 that is in fluid communication with the turbine outlet 27. The exhaust conduit 34 is also in fluid communication with the aftertreatment system 80, and the aftertreatment system 80 receives the exhaust gas from the turbine 26 for aftertreatment. The aftertreatment system 80 may include a variety of catalysts that are configured to chemically convert and / or remove undesirable components from the exhaust gas flow before being discharged into the environment. In the illustrated form, the aftertreatment system 80 includes a diesel particulate filter (DPF) 84 that is configured to reduce particulate emissions. The aftertreatment system 80 of the illustrated form also includes a selective catalytic reduction (SCR) catalyst 86, which is configured to catalyze the reduction of nitrogen oxides (NOx) in combination with a reductant of diesel exhaust fluid (DEF) introduced into the exhaust gas flow, such as by a meter or injector (not shown) upstream of the selective catalytic reduction (SCR) 86. In other embodiments, aftertreatment system 80 may include additional or alternative catalysts, including, for example, oxidation catalysts and ammonia slip catalysts, as well as others that will occur to one of ordinary skill in the art given the benefit of this disclosure.

[0035] For nominal operation, the temperature of one or more portions of the aftertreatment system 80 may need to reach certain temperature conditions. For example, the SCR catalyst 86 may need to reach a minimum temperature in order to operate as intended or desired. Additionally, for certain regeneration modes, higher temperatures may sometimes need to be reached. For example, the diesel particulate filter (DPF) 84 may require elevated temperatures for periodic regeneration to remove accumulated particulate matter.

[0036] The engine system 10 is configured to drive a load 79. In some embodiments, the load 79 may be a generator and the engine system 10 may be configured as a generator set. In certain forms of such embodiments, the engine system 10 may be configured to operate at a predetermined or rated speed that effectively provides an AC output from the generator having a desired frequency of, for example, 50 Hz or 60 Hz. In some embodiments, the engine system 10 may be configured to propel a vehicle, and the load L may be a propulsion load applied to a transmission system operably coupled to the engine system 10, including, to name a few, many load components, such as aerodynamic drag, rolling resistance, and grade / gravity drag. The transmission system operably coupled to the engine system 10 may include, for example, a transmission, a drive shaft, a differential, and a drive wheel.

[0037] refer to Figure 2 , illustrates an example control process 200 (also referred to herein as process 200 ) that may be implemented and executed in conjunction with one or more components of an electronic control system associated with an engine system, such as in conjunction with Figure 1 The process 200 may be used in conjunction with the controller 42 of the described engine system 10, or one or more alternative or additional components of the electronic control system. For illustrative purposes, the process 200 is described in conjunction with a generator set form of the engine system 10. However, it should be understood that the process 200 may be used in conjunction with any form or variation of the engine system 10 disclosed herein as well as other engine system forms and variations.

[0038] When the regeneration trigger condition is set or determined to be true, the process 200 can start at box 210. The regeneration trigger condition can be set or determined to be true in response to a number of conditions or evaluations, including, for example, a timer or counter condition indicating a time or count threshold for triggering catalyst regeneration, a catalyst model condition indicating the state of the catalyst for triggering catalyst regeneration, or a combination of these and / or various other techniques as will occur to those skilled in the art with the benefit of this disclosure. In some forms, the process 200 can be performed with an engine system 10 operating at a predetermined engine speed (e.g., a rated engine speed) or a predetermined engine speed range (e.g., a rated engine speed plus or minus a certain percentage (e.g., + / - 2.5%, or another percentage that provides acceptable performance depending on the application and task in question)) and maintaining the predetermined engine speed or the predetermined engine speed range. In some applications, maintaining a predetermined engine speed or speed range may be a control priority. One such example is the case where the engine system 10 is provided in the form of a generator set, which needs to operate at a given speed in order to match the frequency of the power generation and the frequency of the power grid or load system connected to the generator set. From block 210 , process 200 proceeds to block 212 .

[0039] Frame 212 performs a cylinder change operation (e.g., performs a bank switching algorithm or a cylinder group switching algorithm) that changes selected cylinders of a plurality of cylinders that are operated to provide negative torque via compression braking, and those cylinders that are operated to provide positive torque via fueling and combustion. In some forms, frame 212 may alternate between a first group of cylinders and a second group of cylinders in continuous operation of process 200, wherein one group provides positive torque and the other group of cylinders provides negative torque. In some forms, frame 212 may alternate between a first group of cylinders and a second group of cylinders, wherein one group provides positive torque and the other group provides negative torque, by monitoring the duration of the BF operation and alternating at a predetermined operation duration. Although frame 212 may be omitted, as with other frames of process 200 or subcomponents thereof, the inventors have determined that unexpected results may be obtained by including frame 212. For example, the inventors have determined that the cylinder change, such as provided by frame 212, reduces certain failure modes in which one group of cylinders is not broken or wears unevenly compared to another group of cylinders. From block 212 , process 200 proceeds to block 214 .

[0040] Box 214 performs a brake-fuel (BF) demand assessment in response to the airflow input 202, the engine speed input 204, and the net torque demand input 206. The airflow input 202 provides an indication of intake airflow, which can be determined, for example, based on calculations, models, sensor outputs, or a combination thereof. The engine speed input 204 provides an indication of engine speed, which can be determined, for example, based on the output of an engine speed sensor. The net torque demand input 206 provides an indication of net torque output, which is required of the engine and can be determined, for example, in response to operator or control system requirements. In the context of a generator set form of the engine system 10, the net torque demand input 206 can be determined in response to the electrical load demand on the generator set. In the context of a vehicle propulsion form of the engine system 10, the net torque demand input 206 can be determined in response to operator and control system requirements (e.g., accelerator pedal position, cruise control system requirements, and / or other vehicle system requirements). Box 214 evaluates whether and under what conditions the regeneration target temperature can be achieved based on the received values ​​of the airflow input 202, the engine speed input 204, and the net torque demand input 206. The regeneration target temperature may be an exhaust gas temperature, a catalyst temperature, or another temperature that may be used as an indication or proxy for the conditions under which regeneration may be performed.

[0041] Block 214 may use the engine operating map to assess whether and under what conditions the regeneration target temperature may be achieved. Figure 6An example engine operating diagram 600 is shown, wherein the engine speed (rpm) is on the horizontal axis of the diagram and the engine torque (Nm) is on the vertical axis of the diagram. The engine operating diagram 600 includes multiple operating regions. At a predetermined engine speed 602 (e.g., rated engine operating speed), engine torque ranges 610, 620, and 630 can be used by box 214 to determine whether and under what conditions the regeneration target temperature can be reached. In the engine torque range 610, the regeneration target temperature can be reached without operating the intake throttle (IAT) and without brake-fuel (BF) operation. In the engine torque range 620, the regeneration target temperature can be reached by operating the IAT without BF operation. In the engine torque range 630, the regeneration target temperature can be reached by BF operation, regardless of whether the IAT is operated.

[0042] Block 214 may use a different engine operating map in response to a change in a parameter indicated by block 210. For example, block 210 may include a parameter indicating a first type of regeneration, such as a standard regeneration of a DPF, which may have a first temperature requirement and may be evaluated relative to a first operating engine operating map adjusted to the first temperature requirement. Block 210 may include a parameter indicating a second type of regeneration, such as a first catalyst face plugging, which may have a second temperature requirement greater than the first temperature requirement and may be evaluated relative to a second operating engine operating map adjusted to the second temperature requirement.

[0043] Frame 210 may include parameters indicating other types of regeneration, such as decoking operations or desorption operations, which may have other temperature requirements and may be evaluated relative to additional or alternative working engine operating maps adjusted to the temperature requirements of the operation. Decoking operations include operations configured to or effectively mitigate or reverse catalyst coking that would occur at lower exhaust gas temperatures (e.g., ~180 to 275C). Decoking operations may be promoted, for example, by exhaust gas temperatures above 275C or by exhaust gas temperatures above 300C. Desorption operations include operations configured to or effectively mitigate or reverse the accumulation of hydrocarbons in the SCR catalyst, which hinder the operation of the catalyst by occupying space or position that would otherwise be used to remove NOx. Desorption operations may also include operations configured to and effectively mitigate or reverse the accumulation of urea deposits, which have the effect of hindering its operation or the efficiency of the SCR catalyst. Decoking operations may be promoted, for example, by exhaust gas temperatures above 275C or by exhaust gas temperatures above 300C.

[0044] It should be understood that certain embodiments may utilize a combined decoking and desorption regeneration. For example, a catalyst decoking process may be provided by and triggered by a catalyst desorption process. In such embodiments, operation below a threshold temperature (e.g., 250C) for a threshold time or duration may initiate regeneration to desorb and burn off hydrocarbons accumulated in the catalyst, thereby preventing hydrocarbons from reaching levels that ultimately lead to catalyst coking.

[0045] It should be further understood that box 210 may include parameters indicative of other types of temperature requirements (e.g., temperature requirements for nominal operation of the SCR catalyst), which should be understood as being similar to a catalyst regeneration trigger in the context of process 200 and may be evaluated relative to another operating engine operating map that is adjusted to the SCR catalyst temperature requirement.

[0046] Many additions and variations of the engine operating diagram 600 are envisioned. In embodiments that do not include an IAT, for example, engine torque ranges 620 and 630 can define a range in which the regeneration target temperature can be achieved by BF operation. In some embodiments, the engine torque range 630 can be subdivided into a first sub-range and a second sub-range, in which the regeneration target temperature can be achieved by BF operation alone, and in which the regeneration target temperature can be achieved by BF operation in combination with IAT operation. In some embodiments of generator set applications that require operation at a substantially constant speed, for example, the engine torque range can be determined only for a rated engine speed or only for a rated engine speed band or range. In some embodiments of transportation applications that require operation at multiple engine speeds, for example, the engine torque range can be determined within a larger engine speed range, for example, as indicated by curves 612 and 614 shown in the graph 600, wherein curve 612 indicates the boundary between the engine torque range 610 and the engine torque range 620 in the extended engine speed range, and curve 614 indicates the boundary between the engine torque range 620 and the engine torque range 630 in the extended engine speed range. In some embodiments, the engine torque range can be a predetermined value. In some embodiments, such engine torque range can be determined dynamically. In some embodiments, such engine torque range can be further determined by empirical data, modeling, theoretically based calculations or a combination thereof.

[0047] If frame 214 evaluates that the regeneration target temperature can be reached without operating the IAT and without BF operation (e.g., the engine is operating in the engine torque range 610), the process 200 proceeds to frame 240 where the engine is operated accordingly to provide the regeneration target temperature and perform regeneration. From frame 240, the process 200 can be repeated or terminated and can be initiated later, for example, in the manner described above in conjunction with frame 210.

[0048] If frame 214 evaluates that the regeneration target temperature can be achieved by operating the IAT without BF operation (e.g., the engine is operating in the engine torque range 620), the process 200 proceeds to frame 242 where the engine is operated accordingly to provide the regeneration target temperature and perform regeneration. From frame 240, the process 200 can be repeated or terminated and can be initiated later, for example, in the manner described above in conjunction with frame 210.

[0049] If frame 214 evaluates that the regeneration target temperature can be achieved by BF operation alone or by a combination of BF operation and IAT operation (e.g., the engine is operating in the engine torque range 630), then process 200 proceeds to frame 216 where the engine is operated accordingly to provide the regeneration target temperature and regeneration is performed. From frame 216, process 200 proceeds to frame 218.

[0050] Box 218 deactivates fueling of a group of cylinders selected in conjunction with box 212. From box 218, process 200 proceeds to box 220 which provides a delay for subsequent operation. In some forms, box 220 may provide a delay to allow engine system 10 to respond to a previous control command, which may provide the benefit of reducing noise, vibration, and harshness (NVH). In some forms, box 220 and its associated may be omitted or may be calibrated to provide zero delay. From box 220, process 200 proceeds to box 222 which activates compression braking of another group of cylinders selected in conjunction with box 212. From box 220, process 200 proceeds to box 224.

[0051] Box 224 performs a dynamic BF hold function that controls BF operation in response to the net torque demand input 206. If box 224 determines that the net torque demand input 206 exceeds a maximum value, the process 200 proceeds to box 225 where BF operation is exited by a high net torque demand and proceeds to box 234. If box 224 determines that the net torque demand input 206 does not exceed a maximum value, the process 200 proceeds to box 226 where BF operation is controlled in response to the BF pumping torque model 208 and the net torque demand input 206. The BF pumping torque model 208 may be configured to provide an indication of negative torque generated by the first group of cylinders controlled to provide compression braking. Box 226 determines and outputs one or more BF fueling control parameters that are configured to provide a net torque from the engine system 10 that corresponds to the value of the net torque demand input 206 while taking into account the negative torque value indicated by the BF pumping torque model 208.

[0052] The output of box 226 is provided to a fueling rate limiter box 228, which preferably provides an asymmetric fueling rate limit, including a first limit for increasing the fueling rate and a second limit for decreasing the fueling rate that is different from the first limit. In some forms, the first limit can be set so that no rate limit is applied to the increase in the fueling rate, and the second limit can be set to an empirically determined value to limit the decrease in the fueling rate to provide a reduction or mitigation of one or more NVH metrics. In some forms, both the first limit and the second limit can be set to empirically determined values ​​to limit the decrease in the fueling rate to provide a reduction or mitigation of one or more NVH metrics. These values ​​can be asymmetric or different, or in some forms can be the same. In some forms, the reduction or mitigation of one or more NVH metrics can be balanced or offset by a transient demand response criterion, for example, to provide at least a minimum level of response to an increase in torque demand. In some forms, the first limit and the second limit can be set so that no rate limit is applied to the increase in the fueling rate and no rate limit is applied to the decrease in the fueling rate, or the fueling rate limiter box 228 can be omitted.

[0053] The output of the fueling rate limiter block 228 (or the output of block 226 if block 228 is omitted) is provided to a BF net torque block 230, which determines operation to provide a net torque from the engine system 10 corresponding to the value of the net torque demand input 206, while taking into account the negative torque value indicated by the BF pumping torque model 208 and one or more associated BF fueling values ​​to provide such operation. From block 230, the process 200 proceeds to block 232, which evaluates one or more conditions for ending or transitioning out of BF operation. In the illustrated form, block 232 is configured to evaluate or determine whether the regeneration event has ended or completed (e.g., as indicated by a change in the value of block 210), whether the engine speed or net torque has changed to a work map region or zone outside of the BF operating region or zone, whether a catalyst maximum temperature or temperature condition has been exceeded, and whether a hardware malfunction or failure has occurred (e.g., a malfunction or failure of a compression brake device). If box 232 evaluates or determines that any of the foregoing conditions have been met, process 200 proceeds to box 234 where compression braking of the first group of cylinders is removed, and then to box 236 where a delay is provided after which reactivation of fueling of the first group of cylinders is performed. From box 236, process 200 proceeds to box 240 if engine system 10 is operating in an engine map region that requires base mode operation, or to box 242 if engine system 10 is operating in an engine map region that requires IAT-only mode operation.

[0054] refer to Figure 3 , illustrates an example control process 300 (also referred to herein as process 300 ) that may be implemented and executed in conjunction with one or more components of an electronic control system associated with an engine system, such as in conjunction with Figure 1 Controller 42 of engine system 10 described. Process 300 includes many boxes and associated logic and operations that are substantially the same or similar to the boxes, logic and operations of process 200 and are represented by the same reference numerals used in conjunction with process 200. It should be understood that certain variations of these boxes of process 300 and the interaction and combined operation of the boxes are also contemplated as described below. Process 300 also includes many boxes and associated logic and operations that are different from those of process 200 and are represented by different reference numerals as described below. For illustrative purposes, process 300 is described in conjunction with a fixed service or maintenance event in the form of a vehicle propulsion system of engine system 10. However, it should be understood that process 200 can be used in conjunction with any form or variation of engine system 10 disclosed herein as well as other engine system forms and variations.

[0055] Compared to process 200, process 300 may start at box 311 when a malfunction indicator light (MIL) condition exists. The MIL condition may be triggered, for example, by a sensor and / or model indicating a catalyst malfunction condition (e.g., a first catalyst face plugging condition or another type of catalyst malfunction). The MIL condition may have an associated catalyst health engine speed requirement, which is configured to provide an exhaust gas temperature to restore catalyst health, such as an elevated exhaust gas temperature sufficient to reverse a first catalyst face plugging that would otherwise require catalyst replacement. Such elevated exhaust gas temperature may preferably be at least 360 degrees Celsius or higher, more preferably at least 380 degrees Celsius or higher, or most preferably at least 400 degrees Celsius or higher. In some forms, the provision of such elevated exhaust gas temperature may be limited to stationary vehicle operating conditions, such as a service event initiated by an operator or technician, for example, by pressing a button or otherwise providing input when the vehicle is stationary and operating at idle speed. Therefore, the net torque demand input 206 may be an unloaded, no-task, or idle net torque demand and may be so limited. Additionally, in the event that IAT-only operation cannot meet the necessary exhaust gas temperature, IAT-only operation provided by block 242 in process 200 may be disregarded.

[0056] refer to Figure 4 , illustrates an example control process 400 (also referred to herein as process 400 ) that may be implemented and executed in conjunction with one or more components of an electronic control system associated with an engine system, such as in conjunction with Figure 1 Controller 42 of the described engine system 10. Process 400 includes many boxes and associated logic and operations that are substantially the same or similar to the boxes, logic and operations of process 200 and are represented by the same reference numerals used in conjunction with process 200. It should be understood that certain variations of these boxes of process 500 and the interaction and combined operations of the boxes are also contemplated as described below. Process 400 also includes many boxes and associated logic and operations that are different from those of process 200 and are represented by different reference numerals as described below. For illustrative purposes, process 400 is described in conjunction with an idle coasting operation (e.g., a smart coasting operation) in the form of a vehicle propulsion system of engine system 10. However, it should be understood that process 200 can be used in conjunction with any form or variation of the engine system 10 disclosed herein and other engine system forms and variations.

[0057] Compared to process 200, process 400 includes an idle glide condition enabling block 412 that evaluates whether there are conditions that allow an idle glide operation (e.g., the vehicle is sliding down a hill) or whether the system is operating in an idle glide operation. In addition, process 400 includes a zero net torque fueling command 427 configured to control compression braking to provide zero net torque based on the net torque demand input 206. It should be understood that the zero net torque fueling command 427 is configured to avoid interfering with an idle glide operation that would otherwise occur at a positive net torque or a negative net torque. Process 400 also includes a block group 432 that evaluates one or more conditions for ending a BF operation or transitioning out of a BF operation. In the illustrated form, block 432 is configured to evaluate or determine whether the regeneration event has ended or completed (e.g., as indicated by a change in the value of block 210), whether the vehicle speed or net torque has changed to an operating map region or zone outside of the BF operating region or zone, whether a catalyst maximum temperature or temperature condition has been exceeded, and whether a hardware malfunction or failure has occurred (e.g., a malfunction or failure of a compression brake device).

[0058] refer to Figure 5 , illustrates an example control process 500 (also referred to herein as process 500), which may be implemented and executed in conjunction with one or more components of an electronic control system associated with an engine system, such as in conjunction with Figure 1 Controller 42 of engine system 10 described. Process 500 includes many boxes and associated logic and operations that are substantially the same or similar to the boxes, logic and operations of process 200 and are represented by the same reference numerals used in conjunction with process 200. It should be understood that certain variations of these boxes of process 500 and the interaction and combined operations of the boxes are also contemplated as described below. Process 500 also includes many boxes and associated logic and operations that are different from those of process 200 and are represented by different reference numerals as described below. For illustrative purposes, process 500 is described in conjunction with idle coasting operation in the form of a vehicle propulsion system of engine system 10. However, it should be understood that process 200 can be used in conjunction with any form or variation of engine system 10 disclosed herein as well as other engine system forms and variations.

[0059] Compared to process 200, process 500 includes an idle coasting condition enabling block 512 that evaluates whether conditions exist that allow idle coasting operation (e.g., the vehicle is rolling down a hill and the transmission is out of gear) or whether the system is operating in idle coasting operation. In addition, process 500 may utilize only engine speed input 204 and omit air flow input 202, net torque demand input 206, and zero net torque fueling command 427. Process 500 also includes a block group 432 that evaluates one or more conditions for ending BF operation or transitioning out of BF operation. In the illustrated form, block 432 is configured to evaluate or determine whether the regeneration event has ended or completed (e.g., as indicated by a change in the value of block 210), whether the vehicle speed or net torque has changed to a work map region or zone outside of the BF operating region or zone, whether a catalyst maximum temperature or temperature condition has been exceeded, and whether a hardware malfunction or failure has occurred (e.g., a malfunction or failure of a compression brake device).

[0060] A number of example embodiments shall be further described. A first example embodiment is a method comprising: providing an engine system configured for vehicle propulsion and comprising a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to respective ones of the plurality of cylinders, a compression brake coupled to at least a first group of the plurality of cylinders, an exhaust aftertreatment system comprising a catalyst; operating the engine in an idle glide mode in which the engine is decoupled from a road load; determining a regeneration condition for the catalyst; in response to the determined act, switching operation of the engine to a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from respective ones of the plurality of fuel injectors; wherein the act of switching occurs while maintaining the idle glide mode. In some forms of the first example embodiment, the brake-fuel mode determines a fueling command solely in response to an engine speed input. In some forms of the first example embodiment, the act of converting includes controlling the change in fueling rate using a fueling rate limiter that is asymmetric for increases and decreases in fueling rate. In some forms of the first example embodiment, the act of determining a regeneration condition for the catalyst includes determining a regeneration condition for a diesel particulate filter.

[0061] A second example embodiment is an engine system comprising: an engine configured for vehicle propulsion and comprising a plurality of cylinders; a plurality of fuel injectors configured to provide fuel to respective cylinders of the plurality of cylinders; a compression brake coupled to at least a first group of the plurality of cylinders; an exhaust aftertreatment system comprising a catalyst; and an electronic control system configured to: operate the engine in an idle glide mode in which the engine is decoupled from road loads; determine a regeneration condition of the catalyst; and in response to the regeneration condition of the catalyst, transition operation of the engine to a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from respective fuel injectors of the plurality of fuel injectors; wherein the transition occurs while maintaining the idle glide mode. In some forms of the second example embodiment, the brake-fuel mode uses a zero net torque fueling command in response to a net torque demand of the engine. In some forms of the second example embodiment, the switching includes controlling the change in fueling rate using a fueling rate limiter that is asymmetric for increases and decreases in fueling rate. In some forms of the second example embodiment, the regeneration condition of the catalyst includes determining a need for regeneration of a diesel particulate filter.

[0062] A third example embodiment is a method comprising: providing an engine system comprising a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to respective cylinders of the plurality of cylinders, a compression brake coupled to at least a first group of the plurality of cylinders, an exhaust aftertreatment system comprising a catalyst; operating the engine in a first mode in which the engine operates at a rated speed and a light load of 50% or less of a rated torque with the plurality of fuel injectors providing fuel to each of the plurality of cylinders; determining a regeneration condition of the catalyst; and in response to the act of determining, switching operation of the engine to a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from respective fuel injectors of the plurality of fuel injectors; wherein the act of switching maintains operation of the engine at a predetermined speed or within a predetermined speed range. In some forms of the third example embodiment, the act of switching maintains operation of the engine at the rated speed plus or minus 2.5% or less. In some forms of the third example embodiment, the act of converting includes controlling the change in fueling rate using a fueling rate limiter that is asymmetric for increases and decreases in fueling rate. In some forms of the third example embodiment, the act of determining a regeneration condition for the catalyst includes determining a regeneration condition for a diesel particulate filter. In some forms of the third example embodiment, the act of determining a regeneration condition for the catalyst includes determining a need to alleviate a first catalyst face plugging condition.

[0063] A fourth example embodiment is an engine system comprising: an engine including a plurality of cylinders; a plurality of fuel injectors configured to provide fuel to corresponding cylinders of the plurality of cylinders; a compression brake coupled to at least a first group of the plurality of cylinders; an exhaust aftertreatment system including a catalyst; and an electronic control system configured to: operate the engine in a first mode in which the engine operates at a rated speed and a light load of 50% or less of a rated torque with the plurality of fuel injectors providing fuel to each of the plurality of cylinders; determine a regeneration condition for the catalyst; and in response to the regeneration condition, transition operation of the engine to a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding fuel injectors of the plurality of fuel injectors, wherein during the transition, the electronic control system maintains operation of the engine at a predetermined speed or within a predetermined speed range. In some forms of the fourth example embodiment, during the transition, the electronic control system maintains operation of the engine at the rated speed plus or minus 2.5% or less. In some forms of the fourth example embodiment, during the transition, the electronic control system controls changes in fueling rate using a fueling rate limiter that is asymmetric for increases and decreases in fueling rate. In some forms of the fourth example embodiment, the electronic control system is configured to determine a regeneration condition for a diesel particulate filter. In some forms of the fourth example embodiment, the electronic control system is configured to determine a need to mitigate a plugging condition of a first catalyst face.

[0064] A fifth example embodiment is a method comprising: operating an engine system including a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to the plurality of cylinders, a compression brake system configured to selectively brake at least a first group of the plurality of cylinders, and an exhaust aftertreatment system including at least one catalyst; determining an occurrence of a face plugging condition of the at least one catalyst; in response to the determined act, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding ones of the plurality of fuel injectors; and in the brake-fuel mode, controlling braking of the first group of the plurality of cylinders and fueling of the second group of the plurality of cylinders such that the engine system outputs exhaust gas at a temperature effective to mitigate the face plugging condition of the at least one catalyst. In some forms of the fifth example embodiment, the temperature effective to mitigate the face plugging condition of the at least one catalyst is 360 degrees Celsius or greater. In some forms of the fifth example embodiment, the temperature effective to mitigate the face plugging condition of the at least one catalyst is 380 degrees Celsius or greater. In some forms of the seventh example embodiment, the temperature effective to mitigate the face plugging condition of the at least one catalyst is 400 degrees Celsius or greater. In some forms of the fifth example embodiment, the method is performed when the engine system is in a stationary operating condition or a non-task operating condition.

[0065] A sixth example embodiment is an engine system comprising: an engine including a plurality of cylinders; a plurality of fuel injectors configured to provide fuel to corresponding cylinders of the plurality of cylinders; a compression brake coupled to at least a first group of the plurality of cylinders; an exhaust aftertreatment system including a catalyst; and an electronic control system configured to: determine an occurrence of a face plugging condition of the at least one catalyst, and in response to the occurrence of the face plugging condition, operate the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding fuel injectors of the plurality of fuel injectors, wherein the engine in the brake-fuel mode provides engine exhaust at a temperature effective to mitigate the face plugging condition of the at least one catalyst. In some forms of the sixth example embodiment, the temperature effective to mitigate the face plugging condition of the at least one catalyst is 360 degrees Celsius or greater. In some forms of the sixth example embodiment, the temperature effective to mitigate the face plugging condition of the at least one catalyst is 380 degrees Celsius or greater. In some forms of the sixth example embodiment, the temperature effective to mitigate the face plugging condition of the at least one catalyst is 400 degrees Celsius or greater. In some forms of the sixth example embodiment, the electronic control system is configured to operate the engine in a brake-fuel mode only when the engine system is in a stationary operating condition.

[0066] A seventh example embodiment is a method comprising: operating an engine system including a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to the plurality of cylinders, a compression brake system configured to selectively brake at least a first group of the plurality of cylinders, and an exhaust aftertreatment system including at least one catalyst; determining the occurrence of a face plugging condition of the at least one catalyst; in response to the determined action, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding ones of the plurality of fuel injectors; and in the brake-fuel mode, controlling braking of the first group of the plurality of cylinders and fueling of the second group of the plurality of cylinders such that the engine system outputs exhaust gas at a temperature effective to provide one or both of a decoking operation and a desorption operation of the at least one catalyst. In some forms of the seventh example embodiment, the temperature effective to provide one or both of a decoking operation and a desorption operation is 275 degrees Celsius or greater. In some forms of the seventh example embodiment, the temperature effective to provide one or both of the decoking operation and the desorption operation is 300 degrees Celsius or higher. In some forms of the seventh example embodiment, the decoking operation and the desorption operation are provided in a combined process. In some forms of the seventh example embodiment, the method is performed when the engine system is in a stationary operating condition or a non-task operating condition.

[0067] An eighth example embodiment is an engine system comprising: an engine including a plurality of cylinders; a plurality of fuel injectors configured to provide fuel to corresponding cylinders of the plurality of cylinders; a compression braking system coupled to at least a first group of the plurality of cylinders; an exhaust aftertreatment system including a catalyst; and an electronic control system configured to: determine an occurrence of a face plugging condition of the at least one catalyst; in response to the occurrence of the face plugging condition, operate the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding fuel injectors of the plurality of fuel injectors; and in the brake-fuel mode, control braking of the first group of the plurality of cylinders and fueling of the second group of the plurality of cylinders so that the engine outputs exhaust at a temperature effective to provide one or both of a decoking operation and a desorption operation of the at least one catalyst. In some versions of the eighth example embodiment, the temperature effective to provide one or both of the decoking and desorption operations is 275 degrees Celsius or higher. In some versions of the eighth example embodiment, the temperature effective to provide one or both of the decoking and desorption operations is 300 degrees Celsius or higher.

[0068] In some forms of the eighth example embodiment, the decoking operation and the desorption operation are arranged in a combined operation or triggered by the same operating condition. In some forms of the eighth example embodiment, the electronic control system is configured to operate the engine in a brake-fuel mode only when the engine system is in a stationary operating condition.

[0069] Although the illustrative embodiments of the present disclosure have been illustrated and described in detail in the drawings and the foregoing description, the embodiments are to be considered illustrative rather than restrictive in nature, and it should be understood that only certain exemplary embodiments have been shown and described, and all changes and modifications that fall within the spirit of the claimed invention are protected. It should be understood that although the use of words such as preferred, preferably, preferred or more preferred utilized in the above description indicates that the features described in this way may be more desirable, it may not be necessary, and embodiments lacking the features can be envisioned to be within the scope of the present invention, which is defined by the appended claims. When reading the claims, it is intended that when words such as "one", "an", "at least one" or "at least a portion" are used, unless the contrary is specifically stated, it is not intended to limit the claims to only one item. When the language "at least a portion" and / or "a portion" is used, the item may include a portion and / or the entire item unless the contrary is specifically stated.

Claims

1. A method, comprising: operating an engine system including a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to the plurality of cylinders, a compression braking system configured to selectively brake at least a first group of the plurality of cylinders, and an exhaust aftertreatment system including at least one catalyst; determining the occurrence of a face plugging condition of the at least one catalyst; responsive to the determined action, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding fuel injectors of the plurality of fuel injectors; as well as In the brake-fuel mode, braking of the first group of the plurality of cylinders and fueling of the second group of the plurality of cylinders are controlled such that the engine system outputs exhaust at a temperature effective to reduce the face plugging condition of the at least one catalyst.

2. The method of claim 1, wherein the temperature effective to reduce the face plugging condition of the at least one catalyst is 360 degrees Celsius or higher.

3. The method of claim 1, wherein the temperature effective to reduce the face plugging condition of the at least one catalyst is 380 degrees Celsius or higher.

4. The method of claim 1, wherein the temperature effective to reduce the face plugging condition of the at least one catalyst is 400 degrees Celsius or greater. 5 . The method of claim 1 , wherein the method is performed when the engine system is in a stationary working condition or a non-task working condition.

6. An engine system, comprising: an engine, the engine comprising a plurality of cylinders; a plurality of fuel injectors configured to provide fuel to respective cylinders of the plurality of cylinders; a compression brake coupled to at least a first group of the plurality of cylinders; an exhaust aftertreatment system, the exhaust aftertreatment system comprising a catalyst; and An electronic control system, the electronic control system being configured to: determining the occurrence of a face plugging condition of the at least one catalyst, and responsive to the occurrence of a face plugging condition, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding ones of the plurality of fuel injectors, Wherein operation of the engine in a brake-fuel mode provides engine exhaust at a temperature effective to mitigate the face plugging condition of the at least one catalyst.

7. The engine system of claim 6, wherein the temperature effective to mitigate the face plugging condition of the at least one catalyst is 360 degrees Celsius or greater.

8. The engine system of claim 6, wherein the temperature effective to mitigate the face plugging condition of the at least one catalyst is 380 degrees Celsius or greater.

9. The engine system of claim 6, wherein the temperature effective to mitigate the face plugging condition of the at least one catalyst is 400 degrees Celsius or greater.

10. The engine system of claim 6, wherein the electronic control system is configured to operate the engine in a brake-fuel mode only when the engine system is in a stationary operating condition.

11. A method comprising: operating an engine system including a plurality of cylinders, a plurality of fuel injectors configured to provide fuel to the plurality of cylinders, a compression braking system configured to selectively brake at least a first group of the plurality of cylinders, and an exhaust aftertreatment system including at least one catalyst; determining the occurrence of a face plugging condition of the at least one catalyst; responsive to the determined action, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding fuel injectors of the plurality of fuel injectors; as well as In the brake-fuel mode, braking of the first group of the plurality of cylinders and fueling of the second group of the plurality of cylinders are controlled so that the engine system outputs exhaust at a temperature effective to provide one or both of a decoking operation and a desorption operation of the at least one catalyst.

12. The method of claim 11, wherein the temperature effective to provide one or both of a decoking operation and a desorption operation is 275 degrees Celsius or higher.

13. The method of claim 11, wherein the temperature effective to provide one or both of a decoking operation and a desorption operation is 300 degrees Celsius or higher.

14. The method of claim 11, wherein the decoking operation and the desorption operation are provided in a combined process. 15 . The method of claim 11 , wherein the method is performed when the engine system is in a stationary operating condition or a non-task operating condition.

16. An engine system, the engine system comprising: an engine, the engine comprising a plurality of cylinders; a plurality of fuel injectors configured to provide fuel to respective cylinders of the plurality of cylinders; a compression brake coupled to at least a first group of the plurality of cylinders; an exhaust aftertreatment system, the exhaust aftertreatment system comprising a catalyst; and An electronic control system, the electronic control system being configured to: determining the occurrence of a surface plugging condition of the at least one catalyst, In response to the occurrence of a face plugging condition, operating the engine in a brake-fuel mode in which the compression brake is actuated to provide compression braking of the first group of the plurality of cylinders and a second group of the plurality of cylinders receives and combusts fuel provided from corresponding fuel injectors of the plurality of fuel injectors, and In the brake-fuel mode, braking of the first group of the plurality of cylinders and fueling of the second group of the plurality of cylinders are controlled so that the engine outputs exhaust at a temperature effective to provide one or both of a decoking operation and a desorption operation of the at least one catalyst.

17. The engine system of claim 16, wherein the temperature effective to provide one or both of a decoking operation and a desorption operation is 275 degrees Celsius or greater.

18. The engine system of claim 16, wherein the temperature effective to provide one or both of a decoking operation and a desorption operation is 300 degrees Celsius or greater.

19. The engine system of claim 16, wherein the decoking operation and the desorption operation are arranged in a combined operation or triggered by the same operating condition.

20. The engine system of claim 16, wherein the electronic control system is configured to operate the engine in a brake-fuel mode only when the engine system is in a stationary operating condition.

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