METHOD FOR POST-TREATMENT REGENERATION IN A DIESEL VEHICLE

Abstract

Method (100) for post-treatment regeneration in a diesel vehicle, comprising: Guiding (102) exhaust gases from a diesel engine (12) through an exhaust system (10) within the vehicle, the exhaust system (10) comprising: a diesel oxidation catalyst (DOC) (14) arranged directly downstream of the diesel engine (12), an upstream selective catalytic reduction unit (SCR unit) (16) arranged downstream of the DOC (14), a first diesel exhaust fluid injection device (DEF injection device) (18) arranged between the DOC (14) and the upstream SCR (16) and designed to inject DEF into the exhaust gas, a diesel particulate filter (DPF) (20) which is arranged downstream of the upstream SCR (16) and is designed to capture particulate material from the exhaust gas passing through it, a downstream SCR (22) which is arranged downstream of the DPF (20), a second DEF injection device (24) arranged between the DPF (20) and the downstream SCR (22) and designed to inject DEF into the exhaust gas, and an exhaust system controller (26) which communicates with an engine controller (28), several sensors (30A-30F) within the exhaust system (10) and the first and second DEF injection devices (18, 24), wherein the exhaust system controller (26) is designed to establish and maintain a target exhaust gas temperature (EGT) at an inlet (48) of the upstream SCR (16) and an inlet (50) of the downstream SCR (22) by actively controlling the combustion characteristics of the diesel engine (12) via communication with the engine controller (28), and Initiating (104) a nitrogen dioxide-based (NO2-based) post-treatment regeneration of the DPF (20) by: at least partially deactivating (206) the first DEF injection device (18) and the upstream SCR (16) with the exhaust system controller (26), so that NO2 can pass through the upstream SCR (16), Increasing (108) levels of nitrogen monoxide (NO) in the exhaust gas from the engine (12) with the exhaust system controller (26) via communication with the engine controller (28), Establishing (110) and maintaining a target exhaust gas temperature (target EGT) at an inlet (44) of the DPF (20) (DPF inlet temperature) and a target EGT at an inlet (46) of the DOC (14) (DOC inlet temperature) by actively controlling combustion characteristics of the engine (12) with the exhaust system controller (26) via communication with the engine controller (28), Converting (112) NO in the exhaust gas entering the DOC (14) to NO2 with the DOC (14), and Converting (114) solid carbon-based particulate material that has accumulated in the DPF (20) into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent.

Description

INTRODUCTION

[0001] The present invention relates to a method for aftertreatment regeneration in a diesel vehicle. The present invention generally relates to a control strategy for the aftertreatment regeneration of an exhaust system for an internal combustion engine.

[0002] For example, US patent 2011 / 0283680A1 discloses a method for aftertreatment regeneration in a diesel vehicle, in which exhaust gas from an engine is passed through an oxidation catalyst, an SCR catalyst, and a diesel particulate filter, with a reducing agent being injected between the oxidation catalyst and the SCR catalyst. EP patent 1916029A1 describes a related method.

[0003] Aftertreatment devices for diesel exhaust systems, such as the diesel oxidation catalyst (DOC), the diesel particulate filter (DPF), the lean NOx trap (LNT), and selective catalytic reduction (SCR), have become indispensable. Oxygen-based DPF regeneration occurs at very high temperatures, leading to premature aging of the DPF and SCR components, as well as other exhaust system components, due to thermal degradation.

[0004] Therefore, an object of the invention is to provide an improved method for providing after-treatment regeneration of the DPF and the SCR for a diesel exhaust system, comprising: primary use of an NO2-based after-treatment regeneration of the DPF, occasional use of a short-term O2-based after-treatment regeneration of the DPF when soot reduction within the DPF is ineffective during an NO2-based after-treatment regeneration, and occasional use of SCR desulfation when no current O2-based after-treatment regeneration has been initiated. SUMMARY

[0005] The aforementioned problem is solved by the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims, the description, and the drawings.

[0006] According to several aspects of the present disclosure, a method for aftertreatment regeneration in a diesel vehicle comprises: directing exhaust gases from a diesel engine through an exhaust system within the vehicle, the exhaust system comprising: a diesel oxidation catalyst (DOC) arranged immediately downstream of the diesel engine, an upstream selective catalytic reduction unit (SCR unit) arranged downstream of the DOC, a first diesel exhaust fluid injection device (DEF injection device) arranged between the DOC and the first SCR and designed to inject DEF into the exhaust gas, a diesel particulate filter (DPF) arranged downstream of the first SCR and designed to capture particulate material from the exhaust gas passing through it, and an exhaust system controller connected to an engine controller.several sensors within the exhaust system and the first DEF injection device are in communication, and initiate a nitrogen dioxide-based (NO2-based) aftertreatment regeneration of the DPF by: at least partially deactivating the first DEF injection device and the upstream SCR with the exhaust system controller, so that NO2 can flow through the upstream SCR, increasing levels of nitrogen monoxide (NO) in the exhaust gas from the engine with the exhaust system controller via communication with the engine controller, establishing and maintaining a target exhaust gas temperature (target EGT) at a DPF inlet (DPF inlet temperature) and a target EGT at a DOC inlet (DOC inlet temperature) by actively controlling the combustion characteristics of the engine with the exhaust system controller via communication with the engine controller, converting NO in the exhaust gas entering the DOC,in NO2 with the DOC and conversion of solid carbon-based particulate material that has accumulated in the DPF into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent.

[0007] According to another aspect, increasing the levels of NO in the exhaust gas of the engine with the exhaust system controller via communication with the engine controller also includes selectively adjusting the use of an exhaust gas recirculation unit (EGR unit), an injection timing specification, an injection quantity and a fresh air quantity in the engine with the exhaust system controller via communication with the engine controller.

[0008] According to another aspect, establishing and maintaining a target exhaust gas temperature (target EGT) at a DPF inlet (DPF inlet temperature) and a target EGT at a DOC inlet (DOC inlet temperature) by actively controlling the combustion characteristics of the engine with the exhaust system controller via communication with the engine controller further includes: calculating a target EGT of exhaust gas coming from the engine based on the target EGT at the DPF and the target EGT at the DOC as well as thermodynamic properties of the exhaust system, and establishing and maintaining the target EGT of exhaust gas coming from the engine and the target EGT of exhaust gas coming from the DOC by selectively utilizing late injections and post-injections within the engine with the exhaust system controller via communication with the engine controller.

[0009] According to another aspect, establishing and maintaining a target exhaust gas temperature (target EGT) at a DPF inlet (DPF inlet temperature) also includes establishing and maintaining the DPF inlet temperature between approximately three hundred degrees Celsius and approximately five hundred degrees Celsius.

[0010] According to another aspect, the conversion of NO in the exhaust gas entering the DOC to NO2 with the DOC also includes the conversion of NO in the exhaust gas entering the DOC to NO2 with the DOC using platinum as a catalyst.

[0011] According to another aspect, at least partially deactivating the first DEF injection device and the upstream SCR with the exhaust system controller, so that NO2 can flow through the upstream SCR, furthermore, before increasing levels of NO in exhaust gas from the engine, establishing and maintaining a target DPF inlet temperature and a target DOC inlet temperature, and converting NO in the exhaust gas entering the DOC to NO2 with the DOC: at least partially deactivating the first DEF injection device with the exhaust system controller and allowing residual DEF in the upstream SCR to decrease to acceptable levels.

[0012] According to another aspect, the conversion of solid carbon-based particulate material that has accumulated in the DPF into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent further includes: exposure of the carbon particulate material in the DPF to a platinum and / or a palladium catalyst, wherein the carbon particulate material and the NO2 react to form CO2 and NO, and wherein the NO further reacts with oxygen (O2) to form NO2, with the newly formed NO2 further reacting with carbon particulate material.

[0013] According to another aspect, the procedure further includes: monitoring a level of carbon particulate material in the DPF with the exhaust system controller via communication with a delta pressure sensor and a temperature of the exhaust gas in the DPF and initiating a short-term O2-based aftertreatment regeneration of the DPF when: a level of particulate material in the DPF increases during an NO2-based aftertreatment regeneration or the level of particulate material in the DPF decreases more slowly than a predetermined rate during an NO2-based aftertreatment regeneration.

[0014] According to another aspect, initiating a short-term O2-based DPF aftertreatment regeneration further includes: managing the O2 level in the exhaust gas at the DPF inlet by controlling the O2 levels in the exhaust gas from the engine with the exhaust system controller via communication with the engine controller by selectively adjusting the use of the EGR unit, an injection timing setting, an injection quantity, and a fresh air quantity in the engine with the exhaust system controller via communication with the engine controller; establishing and maintaining a desired EGT between approximately 500 degrees Celsius and 650 degrees Celsius at the DPF inlet by: calculating a target EGT of exhaust gas coming from the engine and a target EGT of exhaust gas coming from the DOC, based on the desired EGT at the DPF inlet and the thermodynamic properties of the exhaust system.and establishing and maintaining the target EGT of exhaust gas coming from the engine and the target EGT of exhaust gas coming from the DOC by actively controlling the combustion characteristics of the engine with the exhaust system controller via communication with the engine controller and selectively utilizing late injections and post-injections in the engine with the exhaust system controller via communication with the engine controller and converting solid, carbon-based particulate material that has accumulated in the DPF into gaseous CO2 using O2 as an oxidizing agent.

[0015] According to another aspect, the process further comprises initiating short-term SCR desulfation and desorbing of sulfur oxides (SOx) within the upstream SCR, wherein the short-term SCR desulfation includes: establishing and maintaining a target desorption EGT at an inlet of the upstream SCR by: calculating a target EGT of exhaust gas coming from the engine and a target EGT of exhaust gas coming from the DOC, based on the target desorption EGT and the thermodynamic properties of the exhaust system, and establishing and maintaining the target EGT of exhaust gas coming from the engine and the target EGT of exhaust gas coming from the DOC.by actively controlling the combustion characteristics of the engine with the exhaust system controller via communication with the engine controller and selectively utilizing late injections and post-injections within the engine with the exhaust system controller via communication with the engine controller.

[0016] According to several aspects of the present disclosure, an exhaust system for a vehicle with a diesel engine comprises a diesel oxidation catalyst (DOC) arranged immediately downstream of the diesel engine, an upstream selective catalytic reduction unit (SCR unit) arranged downstream of the DOC, a first diesel exhaust fluid injection device (DEF injection device) arranged between the DOC and the upstream SCR and designed to inject DEF into the exhaust gas, a diesel particulate filter (DPF) arranged downstream of the upstream SCR and designed to collect particulate material from the exhaust gas passing through it, and an exhaust system controller communicating with an engine controller, several sensors within the exhaust system and the first DEF injection device, wherein the exhaust system controller is designed toto initiate a nitrogen dioxide (NO2)-based DPF aftertreatment regeneration, wherein the exhaust system controller is designed to at least partially deactivate the first DEF injection device and the upstream SCR so that NO2 can flow through the upstream SCR, to increase levels of nitrogen monoxide (NO) in exhaust gas from the engine via communication with the engine controller, to establish and maintain a target exhaust gas temperature (EGT) at an inlet of the DPF (DPF inlet temperature) and a target EGT at an inlet of the DOC (DOC inlet temperature) by actively controlling the combustion characteristics of the engine via communication with the engine controller, wherein the DOC is designed to convert NO in the exhaust gas entering the DOC to NO2, wherein solid carbon-based particulate material that has accumulated in the DPF,using NO2 as an oxidizing agent to convert it into gaseous carbon dioxide (CO2) and NO.

[0017] According to another aspect, the exhaust system controller for increasing NO levels in exhaust gas from the engine is also designed to selectively adjust the use of an exhaust gas recirculation unit (EGR unit), an injection time specification, an injection quantity and a fresh air quantity in the engine via communication with the engine controller.

[0018] According to another aspect, the exhaust system controller is further designed to establish and maintain a target exhaust gas temperature (target EGT) at the DPF inlet and a target EGT at the DOC inlet, to calculate a target EGT of exhaust gas coming from the engine and a target EGT of exhaust gas coming from the DOC based on the thermodynamic target DPF inlet temperature characteristics of the exhaust system, and to establish and maintain the target EGT of exhaust gas coming from the engine and the target EGT of exhaust gas coming from the DOC by selectively utilizing late injections and post-injections within the engine via communication with the engine controller, wherein the target EGT at the DPF inlet is between approximately three hundred degrees Celsius and approximately five hundred degrees Celsius.

[0019] According to another aspect, the DOC includes a platinum catalyst and is designed to convert NO in the exhaust gas entering the DOC into NO2.

[0020] According to another aspect, the exhaust system controller is designed to at least partially deactivate the first DEF injection device and the upstream SCR, so that NO2 can flow through the upstream SCR, and furthermore to at least partially deactivate the first DEF injection device and to allow the reduction of residual DEF in the upstream SCR before increasing levels of NO in exhaust gas from the engine, establishing and maintaining the target DPF inlet temperature and the target DOC inlet temperature and converting NO in the exhaust gas entering the DOC into NO2 in the DOC.

[0021] According to another aspect, the DPF includes a platinum and / or a palladium catalyst, wherein when carbon particle material in the DPF is exposed to the platinum and / or palladium catalyst, the carbon particle material and the NO2 react to form CO2 and NO, and the NO reacts with oxygen (O2) to form NO2, with the newly formed NO2 further reacting with carbon particle material.

[0022] According to another aspect, the exhaust system controller is also designed to monitor the level of carbon particulate material in the DPF via communication with a delta pressure sensor and inputs from temperature sensors within the system, and to initiate a short-term O2-based aftertreatment regeneration of the DPF if the level of carbon particulate material in the DPF increases during an NO2-based aftertreatment regeneration, or if the level of carbon particulate material in the DPF decreases more slowly than a predetermined rate during an NO2-based aftertreatment regeneration.

[0023] According to another aspect, when initiating a short-term O2-based aftertreatment regeneration of the DPF, the exhaust system controller is further designed to manage the level of O2 in the exhaust gas at the DPF inlet by communicating with the engine controller. This involves selectively adjusting the use of the EGR unit, the injection timing, the injection quantity, and the amount of fresh air in the engine; calculating a target EGT of the exhaust gas coming from the engine and a target EGT of the exhaust gas coming from the DOC, based on a desired EGT at the DPF inlet between approximately 500 and 650 degrees Celsius and the thermodynamic properties of the exhaust system; and utilizing selective late injections and post-injections in the engine via communication with the engine controller.to actively control the combustion characteristics of the engine, to establish and maintain the target EGT of exhaust gas coming from the engine and the target EGT of exhaust gas coming from the DOC, and wherein solid carbon-based particulate material that has accumulated in the DPF is converted into gaseous CO2 using O2 as a reducing agent.

[0024] According to another aspect, the exhaust system controller is further designed to initiate short-term SCR desulfation for the desorption of sulfur oxides (SOx) within the upstream SCR, wherein the exhaust system controller is designed to calculate a target EGT of exhaust gas coming from the engine and a target EGT of exhaust gas coming from the DOC, based on a target desorption EGT at an inlet of the upstream SCR and the thermodynamic properties of the exhaust system, to actively control the combustion characteristics of the engine via communication with the engine controller and to selectively use late injections and post-injections within the engine to establish and maintain the target desorption EGT at the inlet of the upstream SCR.

[0025] Further areas of application will become apparent from the description given here. It should be understood that the description and the specific examples serve only for illustrative purposes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described here are for illustrative purposes only; they show: Fig. 1 a schematic representation of a system according to an exemplary embodiment of the present disclosure; and Fig. 2 a flowchart illustrating a method according to an exemplary embodiment of the present disclosure.

[0027] The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of certain components, for example. DETAILED DESCRIPTION

[0028] The following description is for illustrative purposes only. It should be understood that in the drawings, reference numerals indicate similar or corresponding parts and features. Although the figures shown here represent an example with specific arrangements of elements, actual embodiments may contain additional intermediate elements, devices, features, or components. It should also be understood that the figures are for illustrative purposes only and may not be drawn to scale.

[0029] As used here, the term "vehicle" is not limited to automobiles. Although the technology presented here is primarily described in connection with automobiles, it is not limited to automobiles. The concepts can be used in a wide variety of applications, such as in connection with aircraft, watercraft, other vehicles, and consumer electronics components. As used here, the term "approximately" means plus or minus twenty-five degrees with respect to temperatures and plus or minus twenty percent with respect to percentages.

[0030] Diesel engines are widely used in road transport and off-road machinery due to their higher thermal efficiency, better torque, and greater reliability compared to internal combustion engines that use other fossil fuels. Despite the increasing electrification and hybridization of light commercial vehicles, diesel engines continue to play a dominant role in many industries. Diesel engines, due to diffusion combustion, have high emissions of nitrogen oxides (NOx) and particulate matter (PM), and there is a trade-off between these emissions. This trade-off makes reducing diesel engine emissions a challenge. As energy conservation and pollution control become increasingly important, regulations on fuel consumption and emissions control for diesel engines have been introduced worldwide.These regulations have placed considerable pressure on the diesel engine industry and spurred technological innovation. To achieve the goals of energy saving and emission reduction, numerous in-cylinder cleaning technologies have been developed for diesel engines, such as high-pressure fuel injection, multiple injection, variable geometry turbocharging (VGT), two-stage turbocharging, and exhaust gas recirculation (EGR). However, these in-cylinder technologies are insufficient to meet today's stringent emission requirements. Therefore, aftertreatment devices such as the diesel oxidation catalyst (DOC), the diesel particulate filter (DPF), the lean NOx trap (LNT), and selective catalytic reduction (SCR) have become indispensable. This technology can also be used for aftertreatment regeneration in exhaust systems for gasoline engines.Although the terminology used here refers to diesel engines and diesel exhaust systems, it should be clear to those skilled in the art that the new features of the present disclosure are applicable to gasoline-powered internal combustion engines.

[0031] Diesel particulate filters (DPFs) allow exhaust gases to pass through, trapping solid particulate material. To prevent the accumulation of this trapped material, many diesel exhaust systems incorporate oxygen-based regeneration within the DPF. This involves managing the level of oxygen (O2) in the exhaust gases from the engine flowing through the DPF and increasing the temperature of the exhaust gases. This triggers a spontaneous reaction between the particulate material (carbon, C) and oxygen in the DPF, converting the solid carbon particulate material into CO2 gas, which can then flow through the DPF and the exhaust system, according to Equation 1. C + O2 → CO2 Equation 1:

[0032] One disadvantage of such systems is that when using O2 as an oxidizing agent, the temperature required to maintain the chemical reaction is very high, in the range of approximately 500 to 650 degrees Celsius. The regeneration capacity is a function of both the soot load (carbon particulate matter) and the temperature. The performance is linearly proportional to the soot load and exponentially proportional to the temperature. Continuous operation of such an aftertreatment system at these temperatures leads to premature aging of the DPF components and other exhaust system components, particularly the SCR. Simply put, operation at such high temperatures leads to deterioration of the SCR, the DPF, and other exhaust system components, which can result in a deterioration of emissions over time.Therefore, there is a need for an improved system and procedure to provide after-treatment regeneration of the DPF and SCR for a diesel exhaust system.

[0033] With reference to Fig. 1 comprises a diesel exhaust system 10 for a vehicle equipped with a diesel engine 12, according to aspects of the present disclosure, a diesel oxidation catalyst (DOC) 14 arranged directly downstream of the diesel engine 12, an upstream selective catalytic reduction unit (SCR unit) 16 arranged downstream of the DOC 14, a first diesel exhaust fluid injection device 18 (DEF injection device) arranged between the DOC 14 and the upstream SCR 16 and designed to inject DEF into the exhaust gas, a diesel particulate filter (DPF) 20 arranged downstream of the upstream SCR 16 and designed to collect particulate material from the exhaust gas flowing through it, a downstream SCR 22 arranged downstream of the DPF 20, and a second DEF injection device 24.which is arranged between the DPF 20 and the downstream SCR 22 and is designed to inject DEF into the exhaust gas, and an exhaust system controller 26 in communication with a power engine controller 28, several sensors 30A-30F and the first and second DEF injection device 18, 24.,

[0034] The exhaust system controller 26 and the engine controller 28 are each non-generalised electronic control devices comprising a pre-programmed digital computer or processor, memory or non-volatile computer-readable medium used to store data such as control logic, software applications, commands, computer code, data, lookup tables, etc., and a transceiver [or input / output ports]. A computer-readable medium includes any type of medium accessible to a computer, such as read-only memory (ROM), random-access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of storage. A "non-volatile" computer-readable medium excludes wired, wireless, optical, or other communication links carrying volatile electrical or other signals.Non-volatile, computer-readable media includes media on which data can be permanently stored and media on which data can be stored and later overwritten, such as a rewritable optical disc or an erasable storage device. Computer code includes any type of program code, including source code, object code, and executable code.

[0035] According to an exemplary embodiment, the multiple sensors 30A-30F comprise at least a first temperature sensor 30A designed to monitor the temperature of the exhaust gas moving from the engine 12 to the DOC 14, as indicated by arrow 32; a second temperature sensor 30B designed to monitor the temperature of the exhaust gas moving from the DOC 14 to the upstream SCR 16, as indicated by arrow 34; a third temperature sensor 30C designed to monitor the temperature of the exhaust gas moving from the upstream SCR 16 to the DPF 20, as indicated by arrow 36; a fourth temperature sensor 30D designed to monitor the temperature of the exhaust gas moving from the DPF 20 to the downstream SCR 22, as indicated by arrow 38; and a fifth temperature sensor 30E designed to monitor the temperature of the to monitor exhaust gasesthat exits the downstream SCR 22, as indicated by arrow 40, and a delta pressure sensor 30F inside the DPF 20, which is designed to monitor the level of particulate material accumulated in the DPF 20. The multiple sensors include various other sensors contained in the exhaust system 10 and positioned in the engine 12, as well as other sensors positioned in the vehicle and communicating with the exhaust system controller 26.

[0036] According to an exemplary embodiment, the exhaust system controller 26 is designed to initiate nitrogen dioxide (NO2)-based aftertreatment regeneration of the DPF 20 when the level of particulate material in the DPF 20 reaches a predetermined level requiring regeneration. The level of particulate material in the DPF 20 is monitored by the delta pressure sensor 30F. Initiating the NO2-based aftertreatment regeneration is based on feedback from the delta pressure sensor 30F and other information collected by various sensors.

[0037] Known O2-based aftertreatment regeneration processes operate at temperatures between approximately 500 and 650 degrees Celsius, while NO2-based aftertreatment regeneration operates at lower temperatures between approximately 300 and 500 degrees Celsius. Therefore, unlike O2-based aftertreatment regeneration, NO2-based aftertreatment regeneration does not cause thermal deterioration of the exhaust system components.

[0038] During an NO2-based aftertreatment regeneration within the DPF 20, the level of NO2 within the exhaust gases from the engine 12 flowing through the DPF 20 is increased and the temperature of the exhaust gases from the engine 12 flowing through the DPF 20 is controlled, thereby triggering a spontaneous reaction between the particulate material (carbon, C) and NO2 within the DPF 20, whereby the solid carbon particulate material is converted into CO2 gas and nitrogen monoxide (NO) according to Equation 2, which can then flow through the DPF 20 and the exhaust system. C + 2NO2 → CO2 + 2NO Equation 2:

[0039] To facilitate the spontaneous reaction in the DPF 20, the NO2 level in the DPF 20 must be increased, and the exhaust gas temperature in the DPF 20 must be established and maintained. However, any exhaust gas reaching the DPF 20 must first pass through the upstream SCR 16. The upstream SCR 16 is designed to remove NO and NO2 from the exhaust gases flowing through it. To ensure that NO2 reaches the DPF 20 to initiate the NO2-based aftertreatment regeneration, the exhaust system controller 26 is therefore designed to at least partially deactivate the first DEF injector 18 and the first SCR 16 in order to control the performance of the first DEF injector 18 and the upstream SCR 16 so that sufficient NO2 can pass through the upstream SCR 16.To completely deactivate the first SCR, a two-stage process is used. First, the exhaust system controller 26 deactivates the first DEF injector, thus stopping the injection of DEF (ammonia, NH3). Then, before any further action, the exhaust system controller 26 allows a predetermined time interval to elapse so that the remaining DEF can dissipate in the upstream SCR 16. To partially deactivate the upstream SCR, a two-stage process is used. First, the exhaust system controller 26 controls the injection rate of DEF (ammonia, NH3) through the first DEF injector 18. Then, before any further action, the exhaust system controller 26 reduces the ammonia level in the upstream SCR 16 to a level designed to allow sufficient NO2 to pass through the upstream SCR 16.The ammonia in the DEF fluid is designed to consume NO and NO2, and therefore the ammonia levels in the upstream SCR 16 must be controlled during the initiation of an NO2-based aftertreatment regeneration. In some cases, it may not be necessary to completely deactivate the first DEF injector 18 and the upstream SCR 16, but merely to control the performance of the first DEF injector 18 and the upstream SCR 16 so that a controlled amount of ammonia is present in the upstream SCR 16, thus controlling the NO / NO2 conversion that takes place in the upstream SCR 16 and ensuring that sufficient NO2 reaches the DPF 20.

[0040] After the first DEF injection device 18 and the upstream SCR 16 have been neutralized, the exhaust system controller 26 is further designed to increase the levels of nitrogen monoxide (NO) in the exhaust gas from the engine 12 by communicating with the engine controller 28. The DOC 14 is designed to convert the NO in the exhaust gas into NO2, which then spreads to the DPF 20, with the NO2 being used as a reducing agent for the NO2-based aftertreatment regeneration.

[0041] According to an exemplary embodiment, the exhaust system controller 26 for increasing NO levels in the exhaust gas from the engine 12 is further designed to selectively adjust, via communication with the engine controller 28, the use of an exhaust gas recirculation unit (EGR unit) 42, an injection timing setting, an injection quantity, and a fresh air quantity in the engine 12. The exhaust system controller 26 selectively adjusts, via communication with the engine controller 28, the use of all components and processes employed in the engine 12 that are designed to reduce NOx levels in the engine exhaust gas in order to increase the NO level in the engine exhaust gas.

[0042] A known method for reducing NO xExhaust gas recirculation (EGR) is one method used to reduce emissions. In this process, a controllable portion of the engine's exhaust gas is recirculated back into the intake air. A valve, which can be completely closed when necessary, is typically used to control the gas flow. Replacing burnt gas (which no longer participates in combustion) with oxygen-rich air reduces the proportion of the cylinder's volume available for combustion. This results in a correspondingly lower heat release and cylinder peak temperature, and reduces NOₓ formation. xThe recirculated gas can also be routed through an EGR cooler, typically of the air / water type. This reduces the gas temperature, which in turn lowers the cylinder charge temperature when the EGR unit 42 is used. This has two effects: first, the reduction in charge temperature results in a lower peak temperature, and second, the higher density of the cooled EGR gas allows for a higher proportion of EGR to be used. In a diesel engine, the recirculated proportion can be as high as fifty percent under certain operating conditions. While it is known that the use of the EGR unit 42 reduces the amount of NO in the exhaust gas coming from the engine 12, the exhaust system controller 26 can actively control EGR usage to decrease or eliminate the use of the EGR unit 42 in order to increase the amount of NO in the exhaust gas coming from the engine 12.

[0043] As a non-restrictive example and for explanatory purposes, in a hypothetical engine 12 initiating a hypothetical NO2-based aftertreatment regeneration within the DPF 20, the level of NO in the exhaust gases coming from the engine is increased to 600 parts per million (PPM) NO, where 600 ppm is a completely random number used here solely for illustrative and descriptive purposes.

[0044] The DOC 14 uses platinum and oxygen to convert NO in the exhaust gas from engine 12 to NO2, and the DPF 20 converts carbon particle material within the DPF 20 into CO2 and NO, whereby, according to Equation 2 above, the NO2 in the exhaust gas from the DOC (flowing through the upstream SCR 16) is used as an oxidizing agent within the DPF. However, for the chemical reactions shown in Equation 1 and Equation 2 to take place, the temperature in the DOC 14 and the DPF 20 must be at the target temperature.

[0045] According to an exemplary embodiment, the exhaust system controller 26 is further designed to establish and maintain a target exhaust gas temperature (EGT) at an inlet 44 of the DPF 20 (DPF inlet temperature) and a target EGT at an inlet 46 of the DOC 14 (DOC inlet temperature) by actively controlling the combustion characteristics of the engine 12 via communication with the engine controller 28. The DPF inlet temperature is monitored by the third temperature sensor 30C and the DOC inlet temperature is monitored by the first temperature sensor 30A.According to an exemplary embodiment, the target EGT at the inlet 44 of the DPF 20 is only over three hundred degrees Celsius (between approximately three hundred degrees Celsius and approximately five hundred degrees Celsius), as discussed above, to provide a sufficient temperature to maintain the chemical reaction (equation 2) of the NO2-based aftertreatment regeneration while keeping the temperature low enough to minimize the thermal deterioration (“aging”) of the components within the exhaust system 10.

[0046] The main factors influencing the exhaust gas temperature at each point within the exhaust system 10 are the temperature of the exhaust gas leaving the engine 12, i.e., at the point where the exhaust gas reaches its highest temperature, and the thermodynamic properties of the exhaust system 10, which determine how the exhaust gas cools as it flows through the exhaust system 10. Heat loss as the exhaust gas flows from the engine 12 to the DOC 14, from the DOC 14 to the upstream SCR 16, from the upstream SCR 16 to the DPF 20, and from the DPF 20 to the downstream SCR 22 must be taken into account. Thus, the exhaust system controller 26 is further designed to calculate a target EGT of exhaust gas coming from the engine 12 and, more importantly, a target EGT of exhaust gas coming from the DOC 14, backwards based on the target DPF inlet temperature and the thermodynamic properties of the exhaust system 10.

[0047] For example, if, based on the thermodynamics of the exhaust system 10, the target temperature inside the DPF 20 (DPF inlet temperature) required to support aftertreatment regeneration, as measured by the third temperature sensor 30C, is four hundred degrees Celsius, then the temperature inside the upstream SCR 16, as measured by the second temperature sensor 30B, must be four hundred and fifty degrees Celsius and the temperature inside the DOC 14 (DOC inlet temperature) must be five hundred degrees Celsius.

[0048] According to an exemplary embodiment, the exhaust system controller 26 is designed to establish and maintain the target EGT of exhaust gas coming from the engine 12 and the target EGT of exhaust gas coming from the DOC 14 by selectively utilizing late injections and post-injections within the engine 12 via communication with the engine controller 28.

[0049] A later ignition timing is a well-known strategy for quickly warming up the catalytic converter. Delayed combustion reduces the work transfer from the cylinder gases to the piston, resulting in a higher exhaust gas temperature. At a constant engine torque, the reduced fuel conversion efficiency associated with late combustion necessitates higher fuel and air flow rates. Thus, late ignition leads to a higher sensible enthalpy flow from the engine due to both higher temperatures and greater mass flow rates.

[0050] Late post-injection of fuel is a well-established strategy for controlling exhaust gas temperature and achieving high exhaust gas temperatures for diesel particulate filter (DPF) regeneration. Post-injection is an injection strategy in which a specific amount of fuel is injected after the main injection / combustion event to release heat. This post-injected fuel is further broken down into small molecular hydrocarbons, then expelled from the cylinder and oxidized by the DOC (diesel oxidizer) to generate a high temperature for DPF regeneration. This post-injected fuel can also improve combustion by oxidizing previously generated soot and NOx, thus reducing particulate emissions.Fuel injected during an exhaust stroke of the engine cycle provides temperature control at the outlet of the DOC 14. The temperature of the exhaust gas leaving engine 12 is generally lower than the target temperature of the DOC 14. The fuel injected during the exhaust stroke does not burn in the cylinder but ignites in the DOC 14, generating heat and raising the temperature of the exhaust gas coming from engine 12 to the target EGT of the exhaust gas coming from the DOC 14.

[0051] Thus, the exhaust system controller 26 maintains elevated levels of NO in the exhaust gas coming from the engine and maintains the target temperature at the DPF 20 and at the DOC 14, with the DOC 14 being designed to convert NO in the exhaust gas entering the DOC 14 into NO2.

[0052] The main functions of the DOC 14 are the oxidation of CO, unburned hydrocarbons, and NO, while active hydrocarbon oxidation can also be used to generate exotherms required for downstream components. The DOC 14 promotes the oxidation of exhaust gas components by oxygen, which is present in large quantities in diesel exhaust. When carbon monoxide (CO), gaseous hydrocarbons (HC), the organic fraction of diesel particulates (OF), and unregulated emissions such as aldehydes or PAHs are passed over an oxidation catalyst, they can be oxidized to harmless products and thus controlled by the DOC 14. In the present system 10, an important function of the DOC 14 is to oxidize nitric oxide (NO) to nitrogen dioxide (NO2) using platinum as a catalyst.

[0053] According to an exemplary embodiment, the DOC 14 is designed to convert approximately fifty percent of the NO in the exhaust gas entering the DOC 14 to NO2. The conversion rate of NO to NO2 depends on many factors and can be more or less than fifty percent, depending on the requirements of the DPF 20 and the overall design of the system 10. Ultimately, the DOC 14 is designed to convert NO to NO2 at a rate sufficient to ensure that an adequate amount of NO2 reaches the DPF. Referring to the non-limiting hypothetical example given above, in which the exhaust gas coming from the engine contains 600 ppm NO, the DOC 14 will convert approximately half of the NO in the exhaust gas from the engine 12 to NO2, with the exhaust gas exiting the DOC 14 containing 300 ppm NO and 300 ppm NO2.

[0054] When carbon particle material in the DPF 20 is exposed to a platinum and / or palladium catalyst, the solid carbon-based particle material that has accumulated in the DPF 20 is converted in the DPF 20 into gaseous carbon dioxide (CO2) and NO by using the NO2 present in the exhaust gas as an oxidizing agent for the NO2-based after-treatment regeneration.

[0055] An additional advantage of NO2-based post-treatment regeneration is that once the chemical reaction (equation 2) starts inside the DPF, the NO by-product from equation 2 reacts further with oxygen due to the presence of the platinum catalyst, forming additional NO2 as shown in equation 3. C + NO2 → CO2 + NO, Equation 2: : NO + O2 → NO2. Equation 3:

[0056] Once the chemical reaction of the NO2-based aftertreatment regeneration begins within the DPF 20, the reaction of Equation 3 maintains the level of NO2 in the DPF so that it continues to react with any remaining carbon particulate matter (soot) in the DPF 20 for the duration of the exhaust gas's passage through the DPF 20. Once the carbon particulate matter has been broken down and more NO2 is generated by the NO2-based aftertreatment regeneration within the DPF 20, the exhaust gas leaving the DPF 20 contains less NO and more NO2. Referring again to the non-restrictive example where the exhaust gas coming from the DOC 14 contains 300 ppm NO and 300 ppm NO2, the exhaust gas after passing through the DPF 20 now contains 150 ppm NO and 450 ppm NO2.Exhaust gas from the DPF 20 migrates to the downstream SCR 22, which is designed to convert the NO and NO2 remaining in the exhaust gas from the DPF 20 into nitrogen gas (N2) and water (H2O), as is known in the industry.

[0057] Thus, the exhaust system controller 26 can minimize the thermal deterioration of the system 10 by using a control strategy that includes NO2-based aftertreatment regeneration to remove soot accumulation in the DPF 20. However, NO2-based aftertreatment regeneration operates more slowly than conventional O2-based aftertreatment regeneration. NO2-based aftertreatment regeneration removes soot from the DPF 20 at a rate that may be less than half the soot removal rate achieved with conventional O2-based aftertreatment regeneration. This means that there may be times when a strategy that includes NO2-based DPF aftertreatment regeneration cannot keep pace with the rate of soot accumulation in the DPF.

[0058] According to an exemplary embodiment, the exhaust system controller 26, when performing an NO2-based aftertreatment regeneration of the DPF 20, is further designed to monitor a level of carbon particulate material in the DPF 20 via communication with the delta pressure sensor 30F and to initiate a short-term O2-based aftertreatment regeneration of the DPF 20 if: 1) a level of particulate material in the DPF 20 increases during an NO2-based aftertreatment regeneration or 2) the level of particulate material in the DPF 20 decreases more slowly than a predetermined rate during an NO2-based aftertreatment regeneration.

[0059] Thus, the control strategy includes a fallback option for situations in which, due to the operating conditions of the engine 12, soot deposits accumulate in the DPF 20 faster than NO2-based aftertreatment regeneration can compensate for. Therefore, the exhaust system controller 26 performs a short-term O2-based aftertreatment regeneration at correspondingly higher temperatures (five hundred to six hundred and fifty degrees Celsius) for a brief period. This oxidizes carbon particulate material in the DPF 20 much more rapidly, reducing the carbon level in the DPF 20 back to controllable values. The exhaust system controller 26 can then switch back to NO2-based aftertreatment regeneration. Ideally, the timeframe would be limited to a few minutes (one to five). The shorter the timeframe, the lower the thermal deterioration of the exhaust system 10 components.However, the exhaust system controller 26 is designed to initiate short-term O2-based aftertreatment regeneration for a sufficient period of time to reduce the carbon level in the DPF to controllable values. Therefore, under extreme circumstances, the timeframe of short-term O2-based aftertreatment regeneration can extend beyond a few minutes. This short-term O2 aftertreatment regeneration is only performed for short periods and only in extreme situations where the NO2-based aftertreatment regeneration of the DPF 20 cannot keep pace with the accumulation of carbon particulate material and the exhaust system controller 26 determines that a temporary increase in the soot oxidation rate is necessary.

[0060] When initiating short-term O2-based aftertreatment regeneration within the DPF 20, the exhaust system controller 26 is further designed to increase the O2 level in the exhaust gas at the DPF inlet 44 by communicating with the engine controller 28. This is achieved through selective adjustment of the EGR unit 42's use within the engine 12, fresh air control, and injection timing and quantity. This control is generally a reduction in the amount of O2, as the incoming ambient air contains 21% oxygen, and the appropriate O2 level required for O2-based aftertreatment regeneration is less than 21%. Control of O2 levels in the exhaust gas is primarily achieved through fresh air control and injection timing / quantity adjustment.

[0061] According to an exemplary embodiment, the exhaust system controller 26 is further designed to establish and maintain a target exhaust gas temperature (target EGT) at the inlet 44 of the DPF 20 by actively controlling the combustion characteristics of the engine 12 via communication with the engine controller 28. The DPF inlet temperature is monitored by the third temperature sensor 30C. According to an exemplary embodiment, the target EGT at the inlet 44 of the DPF 20, as explained above, is between approximately 500 degrees Celsius and approximately 650 degrees Celsius to provide a sufficient temperature to maintain the chemical reaction (Equation 1) of the O2-based aftertreatment regeneration.

[0062] As explained above, the exhaust system controller 26 is further designed to calculate a target EGT of exhaust gas coming from the engine 12 and an EGT of exhaust gas coming from the DOC 14, working backwards based on the target DPF inlet temperature for the O2-based aftertreatment regeneration and the thermodynamic properties of the exhaust system 10.

[0063] For example, based on the thermodynamics of the exhaust system 10, if the target temperature inside the DPF 20 (DPF inlet temperature), as measured by the third temperature sensor 30C, which is required to support the O2-based aftertreatment regeneration, is 600 degrees Celsius, the temperature inside the upstream SCR 16, as measured by the second temperature sensor 30B, must be 650 degrees Celsius, and the temperature inside the DOC 14 (DOC inlet temperature) must be 700 degrees Celsius, the temperatures being non-limiting and serving only for illustrative purposes.

[0064] According to an exemplary embodiment, the exhaust system controller 26 is designed to establish and maintain the target EGT of exhaust gas coming from the engine 12 and the target EGT of exhaust gas coming from the DOC by selectively utilizing late injections and post-injections within the engine 12 via communication with the engine controller 28, as explained above.

[0065] When carbon particle material in the DPF 20 is exposed to a platinum and / or palladium catalyst, the solid carbon-based particle material that has accumulated in the DPF 20 is converted into gaseous carbon dioxide (CO2) by using the O2 present in the exhaust gas as an oxidizing agent for the O2-based after-treatment regeneration.

[0066] One advantage of high-temperature, oxygen-based aftertreatment regeneration is that the high temperatures in the upstream SCR 16 and downstream SCR 22 help reduce the amount of sulfur oxides (SOx) absorbed and accumulated in these systems. Despite the use of low-sulfur fuels and desulfurization processes, exhaust gases still contain a few parts per million (ppm) of SO2, and the presence of such trace amounts of sulfur can poison the active sites of the upstream SCR 16 and downstream SCR 22 by forming inactive metal sulfate species. This deactivation significantly impairs catalytic performance.

[0067] Part of the control strategy for the exhaust system 10 is therefore to ensure that occasional desorption of absorbed SOx takes place within the upstream SCR 16 and the downstream SCR 22. Furthermore, if a predetermined period of time has elapsed during which an O2-based high-temperature DPF aftertreatment regeneration has not been initiated, or if an estimated sulfur level exceeds a predetermined threshold, the exhaust system controller 26 is designed to initiate short-term SCR desulfation to desorb SOx within the upstream SCR 16 and / or the downstream SCR 22.

[0068] The exhaust system controller 26 is further designed to establish and maintain a target exhaust gas temperature (EGT) at an inlet 48 of the upstream SCR 16 and an inlet 50 of the downstream SCR 22 by actively controlling the combustion characteristics of the engine 12 via communication with the engine controller 28. The exhaust gas temperature at inlet 48 of the upstream SCR 16 is monitored by the second temperature sensor 30B, and the exhaust gas temperature at inlet 50 of the downstream SCR 22 is monitored by the fourth temperature sensor 30D. The target EGT at the upstream SCR 16 and / or the downstream SCR 22 is the temperature sufficient to cause spontaneous desorption (removal) of SOx from the upstream SCR 16 and / or the downstream SCR 22, as is known in the industry.

[0069] As discussed above, the exhaust system controller 26 is further designed to calculate a target EGT of exhaust gas coming from the engine 12, going backwards based on the target exhaust gas temperature (target EGT) at the inlet 48 of the upstream SCR 16 and / or the inlet 50 of the downstream SCR 22 for the removal of SOx and the thermodynamic properties of the exhaust system 10.

[0070] For example, based on the thermodynamics of the exhaust system 10, if the target temperature in the downstream SCR 22, as measured by the fourth temperature sensor 30D, which is required to assist in the removal of SOx, is 550 degrees Celsius, then the temperature in the DPF 20, as measured by the third temperature sensor 30C, must be 600 degrees Celsius, the temperature in the first SCR 16, as measured by the second temperature sensor 30B, must be 650 degrees Celsius, and the temperature in the DOC 14 (DOC inlet temperature) must be 700 degrees Celsius, the temperatures being non-limiting and serving only for illustrative purposes.

[0071] According to an exemplary embodiment, the exhaust system controller 26 is designed to establish and maintain the target EGT of exhaust gas coming from the engine 12 and the target EGT of exhaust gas coming from the DOC 14 by selectively utilizing late injections and post-injections within the engine 12 via communication with the engine controller 28, as discussed above.

[0072] Thus, a control strategy using the system 10 of the present disclosure comprises 1) primarily the use of NO2-based aftertreatment regeneration of the DPF 20 by intrusively and actively controlling the function of the EGR42 and the combustion characteristics (injection timing, injection quantity and fresh air quantity) within the engine 12 to achieve NO2 values ​​and temperatures within the exhaust gas to support the NO2-based aftertreatment regeneration, 2) occasionally, if the soot reduction within the DPF 20 is ineffective during NO2-based aftertreatment regeneration, the use of O2-based aftertreatment regeneration of the DPF 20 for a short period by intrusively and actively controlling the function of the EGR42 and the combustion characteristics (injection timing, injection quantity and fresh air quantity) within the engine 12.to achieve O2 levels and temperatures within the exhaust gas to support O2-based aftertreatment regeneration, and 3) occasionally, if no recent O2-based aftertreatment regeneration has been initiated, to use SCR desulfation of the upstream and / or downstream SCR 16, 22 to remove SOx from the upstream and / or downstream SCR 16, 22 by intrusive and active control of the EGR function and combustion characteristics (injection timing, injection quantity and fresh air quantity) within the engine 12 to achieve O2 levels and temperatures within the exhaust gas to support SOx desorption within the upstream and / or downstream SCR 16, 22.

[0073] With reference to Fig.2 comprises a method 100 for aftertreatment regeneration in a diesel vehicle, starting at block 102, a routing of exhaust gases from a diesel engine 12 through an exhaust system 10 within the vehicle, wherein the exhaust system 10 comprises a diesel oxidation catalyst (DOC) 14 arranged immediately downstream of the diesel engine 12, a first selective catalytic reduction (SCR) unit 16 arranged downstream of the DOC 14, a first diesel exhaust fluid injection device 18 (DEF injection device) arranged between the DOC 14 and the upstream SCR 16 and designed to inject DEF into the exhaust gas, a diesel particulate filter (DPF) 20 arranged downstream of the upstream SCR 16 and designed to capture particulate material from the exhaust gas flowing through it, and a downstream SCR unit 22 arranged downstream of the DPF 20 is arranged, a second DEF injection device 24,which is arranged between the DPF 20 and the downstream SCR 22 and is adapted for injecting DEF into the exhaust gas, and comprises an exhaust system controller 26 in communication with a power engine controller 28, several sensors 30A-30F within the exhaust system 10 and the first and second DEF injection device 18, 24.

[0074] Method 100 further comprises, with reference to Block 104, initiating a nitrogen dioxide (NO2)-based aftertreatment regeneration of the DPF 20 by, with reference to Block 106, at least partially deactivating the first DEF injection device 18 and the upstream SCR 16 with the exhaust system controller, so that NO2 can flow through the upstream SCR 16; with reference to Block 108, increasing levels of nitrogen monoxide (NO) in the exhaust gas from the engine 12 with the exhaust system controller 26 via communication with the engine controller 28; and with reference to Block 110, establishing and maintaining a target exhaust gas temperature (target EGT) at an inlet 44 of the DPF 20 (DPF inlet temperature) and a target EGT at an inlet 46 of the DOC 14 (DOC inlet temperature) by actively controlling the combustion characteristics. the power unit 12 with the exhaust system controller 26 via communication with the power unit controller 28,with reference to Block 112, conversion of NO within the exhaust gas entering the DOC 14 with the DOC 14 to NO2, with reference to Block 114, conversion of solid carbon-based particulate material that has accumulated in the DPF 20 into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent, and with reference to Block 116, conversion of NO and NO2 within the exhaust gas from the DPF 20 to nitrogen gas (N2) and water (H2O) in the downstream SCR 22.

[0075] According to an exemplary embodiment, increasing the levels of NO in the exhaust gas from the engine 12 with the exhaust system controller 26 via communication with the engine controller 28 in block 108 further comprises selectively adjusting the use of an exhaust gas recirculation unit (EGR unit) 42, an injection timing specification, an injection quantity and a fresh air quantity in the engine 12 with the exhaust system controller 26 via communication with the engine controller 28.

[0076] According to an exemplary embodiment, establishing and maintaining a target exhaust gas temperature (target EGT) at the inlet 44 of the DPF 20 and a target EGT at the inlet 46 of the DOC 14 by actively controlling the combustion characteristics of the engine 12 with the exhaust system controller 26 via communication with the engine controller 28 in block 110 further comprises, with reference to block 118, calculating a target EGT of exhaust gas coming from the engine 12 and a target EGT of exhaust gas coming from the DOC 14 based on the target DPF inlet temperature and the thermodynamic properties of the exhaust system 10, and, with reference to block 120, establishing and maintaining the target EGT of exhaust gas coming from the engine 12 and the target EGT of exhaust gas coming from the DOC 14.by selectively using late injections and post-injections within the engine 12 with the exhaust system controller 26 via communication with the engine controller 28.

[0077] According to an exemplary embodiment, establishing and maintaining a target exhaust gas temperature (target EGT) at the inlet 44 of the DPF 20 at block 110 further comprises establishing and maintaining the DPF inlet temperature of only more than three hundred degrees Celsius (between approximately three hundred degrees Celsius and approximately five hundred degrees Celsius).

[0078] According to an exemplary embodiment, the conversion of NO in the exhaust gas entering the DOC 14 to NO2 at block 112 with the DOC 14 further comprises converting approximately fifty percent of the NO in the exhaust gas entering the DOC 14 to NO2 with the DOC 14 using platinum as a catalyst.

[0079] According to an exemplary embodiment, at least partially deactivating the first DEF injection device 18 and the upstream SCR 16 with the exhaust system controller in block 106, so that NO2 can pass through the upstream SCR 16, furthermore before increasing levels of NO in the exhaust gas of the engine 12 in block 108 and before establishing and maintaining a target inlet temperature of the DPF 20 and a target inlet temperature of the DOC 14 in block 110 and before converting NO in the exhaust gas entering the DOC 14 into NO2 with the DOC 14 in block 112, includes at least partially deactivating the first DEF injection device 18 with the exhaust system controller 26 and enabling the reduction of residual DEF in the upstream SCR 16.

[0080] According to an exemplary embodiment, the conversion (oxidization) of solid carbon-based particulate material that has accumulated in the DPF 20 into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent in block 114 further comprises exposing carbon particulate material in the DPF 20 to a platinum and / or palladium catalyst, wherein the carbon particulate material and the NO2 react to form CO2 and NO, and wherein the NO further reacts with oxygen (O2) to form NO2, the newly formed NO2 further reacting with carbon particulate material.

[0081] According to an exemplary embodiment, the method 100 further comprises, with reference to block 122, monitoring a level of carbon particle material within the DPF 20 with the exhaust system controller 26 via communication with a delta pressure sensor 30F and, with reference to block 124, then, if the exhaust system is not currently performing NO2-based aftertreatment regeneration, a return to block 122 and then, if the exhaust system is currently performing NO2-based aftertreatment regeneration, a advance to block 126.

[0082] If, during NO2-based aftertreatment regeneration in Block 126, the level of particulate material within the DPF 20 increases, Procedure 100, which transitions to Block 128, includes initiating a short-term O2-based aftertreatment regeneration of the DPF 20. If, during NO2-based aftertreatment regeneration in Block 126, the level of particulate material in the DPF 20 does not increase, Procedure 100 includes transitioning to Block 130.

[0083] If, during the NO2-based aftertreatment regeneration in Block 130, the level of particulate material within the DPF decreases more slowly than a predetermined rate, Procedure 100, which then transitions to Block 128, includes initiating a short-term O2-based aftertreatment regeneration of the DPF 20. If, during the NO2-based aftertreatment regeneration in Block 130, the level of particulate material within the DPF does not decrease more slowly than a predetermined rate, Procedure 100 includes transitioning to Block 132.

[0084] In block 128, initiating a short-term O2-based aftertreatment regeneration of the DPF 20 further comprises, progressing to block 140, increasing the level of O2 in the exhaust gas at the DPF inlet 44 by controlling levels of O2 in exhaust gas from the engine 12 with the exhaust system controller 26 via communication with the engine controller 28 by selectively adjusting the use of the EGR unit 42, an injection timing specification, an injection quantity and a fresh air quantity in the engine 12 with the exhaust system controller 26 via communication with the engine controller 28, with reference to block 142, establishing and maintaining a desired EGT between approximately 500 degrees Celsius and 650 degrees Celsius at the inlet 44 of the DPF 20 by, progressing to block 144, calculating a target EGT of exhaust gas coming from the engine 12, and a target EGT of exhaust gas coming from DOC 14,based on the desired EGT at the DPF inlet 44 and the thermodynamic properties of the exhaust system 10, and, with reference to block 146, establishing and maintaining the target EGT of exhaust gas coming from the engine 12 and the target EGT of exhaust gas coming from the DOC 14 by actively controlling the combustion characteristics of the engine 12 with the exhaust system controller 26 via communication with the engine controller 28 and selectively utilizing late injections and post-injections within the engine 12 with the exhaust system controller 26 via communication with the engine controller 28. With reference to block 148, the method further comprises converting solid carbon-based particulate material that has accumulated in the DPF 20 into gaseous CO2 using O2 as an oxidizing agent.

[0085] If, at block 132, a predetermined time window has not elapsed since the exhaust system controller 26 initiated a short-term O2-based aftertreatment regeneration, or if the estimated sulfur levels exceed a predetermined threshold, process 100 returns to block 122. If, at block 132, a predetermined time window has elapsed since the exhaust system controller 26 initiated a short-term O2-based aftertreatment regeneration, then process 100, transitioning to block 134, further includes initiating a short-term SCR desulfation and desorbing sulfur oxides (SOx) within the upstream SCR 16 and / or the downstream SCR 22.

[0086] According to an exemplary embodiment, initiating short-term SCR desulfation and desorbing of sulfur oxides (SOx) within the upstream SCR 16 and / or the downstream SCR 22 at block 134 further comprises establishing and maintaining a target desorption EGT within an inlet 48 of the upstream SCR 16 and / or an inlet 50 of the downstream SCR 22 by, transitioning to block 136, calculating a target EGT of exhaust gas coming from the engine 12 and a target EGT of exhaust gas coming from the DOC 14, based on the target desorption EGT and the thermodynamic properties of the exhaust system 10, and, transitioning to block 138, establishing and maintaining the target EGT of exhaust gas coming from the engine 12 and the target EGT of exhaust gas coming from the DOC 14 comes,by actively controlling the combustion characteristics of the engine 12 with the exhaust system controller 26 via communication with the engine controller 28 and selectively using late injections and post-injections within the engine 12 with the exhaust system controller 26 via communication with the engine controller 28.

[0087] A system and a method of the present disclosure offer the advantage of providing a control strategy for performing aftertreatment regenerations within a diesel exhaust system 10, comprising: 1) primary use of NO2-based aftertreatment regeneration of the DPF 20 by intrusive and active control of the function of the EGR 42 and the combustion characteristics within the engine 12 to achieve NO2 levels and temperatures within the exhaust gas to support the NO2-based aftertreatment regeneration; 2) occasional use, when soot reduction within the DPF 20 is ineffective during NO2-based aftertreatment regeneration, of O2-based aftertreatment regeneration of the DPF 20 for a short period by intrusive and active control of the function of the EGR 42 and the combustion characteristics (injection timing, injection quantity, and fresh air quantity) within the engine 12.to achieve O2 levels and temperatures within the exhaust gas to support O2-based aftertreatment regeneration, and 3) occasional use, when no recent O2-based aftertreatment regeneration has been initiated, of SCR desulfation of the upstream and / or downstream SCR 16, 22 to remove SOx from the upstream and / or downstream SCR 16, 22 by intrusive and active control of the EGR function and the combustion characteristics (injection timing, injection quantity and fresh air quantity) within the engine 12 to achieve O2 levels and temperatures within the exhaust gas to support SOx desorption within the upstream and / or downstream SCR 16, 22.

[0088] The description of the present revelation is merely exemplary.

Claims

[1] Method (100) for post-treatment regeneration in a diesel vehicle, comprising: Guiding (102) exhaust gases from a diesel engine (12) through an exhaust system (10) within the vehicle, the exhaust system (10) comprising: a diesel oxidation catalyst (DOC) (14) arranged directly downstream of the diesel engine (12), an upstream selective catalytic reduction unit (SCR unit) (16) arranged downstream of the DOC (14), a first diesel exhaust fluid injection device (DEF injection device) (18) arranged between the DOC (14) and the upstream SCR (16) and designed to inject DEF into the exhaust gas, a diesel particulate filter (DPF) (20) which is arranged downstream of the upstream SCR (16) and is designed to capture particulate material from the exhaust gas passing through it, a downstream SCR (22) which is arranged downstream of the DPF (20), a second DEF injection device (24) arranged between the DPF (20) and the downstream SCR (22) and designed to inject DEF into the exhaust gas, and an exhaust system controller (26) which communicates with an engine controller (28), several sensors (30A-30F) within the exhaust system (10) and the first and second DEF injection devices (18, 24), wherein the exhaust system controller (26) is designed to establish and maintain a target exhaust gas temperature (EGT) at an inlet (48) of the upstream SCR (16) and an inlet (50) of the downstream SCR (22) by actively controlling the combustion characteristics of the diesel engine (12) via communication with the engine controller (28), and Initiating (104) a nitrogen dioxide-based (NO2-based) post-treatment regeneration of the DPF (20) by: at least partially deactivating (206) the first DEF injection device (18) and the upstream SCR (16) with the exhaust system controller (26), so that NO2 can pass through the upstream SCR (16), Increasing (108) levels of nitrogen monoxide (NO) in the exhaust gas from the engine (12) with the exhaust system controller (26) via communication with the engine controller (28), Establishing (110) and maintaining a target exhaust gas temperature (target EGT) at an inlet (44) of the DPF (20) (DPF inlet temperature) and a target EGT at an inlet (46) of the DOC (14) (DOC inlet temperature) by actively controlling combustion characteristics of the engine (12) with the exhaust system controller (26) via communication with the engine controller (28), Converting (112) NO in the exhaust gas entering the DOC (14) to NO2 with the DOC (14), and Converting (114) solid carbon-based particulate material that has accumulated in the DPF (20) into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent. [2] Method (100) according to claim 1, wherein increasing the levels of NO in the exhaust gas from the engine (12) with the exhaust system controller (26) via communication with the engine controller (28) further comprises selectively adjusting (108) the use of an exhaust gas recirculation unit (EGR unit) (42), an injection time specification, an injection quantity and a fresh air quantity in the engine (12) with the exhaust system controller (26) via communication with the engine controller (28). [3] Method (100) according to claim 2, wherein establishing and maintaining a target exhaust gas temperature (target EGT) at an inlet (44) of the DPF (20) (DPF inlet temperature) and a target EGT at an inlet (46) of the DOC (14) (DOC inlet temperature) by actively controlling combustion characteristics of the engine (12) with the exhaust system controller (26) via communication with the engine controller (28) further comprises: Calculating (118) a target EGT of exhaust gas coming from the engine (12) based on the target EGT at the DPF (20) and the target EGT at the DOC (14) as well as thermodynamic properties of the exhaust system (10) and Establishing (120) and maintaining the target EGT of exhaust gas coming from the engine (12) and the target EGT of exhaust gas coming from the DOC (14) by selectively utilizing late injections and post-injections within the engine (12) with the exhaust system controller (26) via communication with the engine controller (28). [4] Method (100) according to claim 3, wherein establishing and maintaining a target exhaust gas temperature (target EGT) at an inlet (44) of the DPF (20) (DPF inlet temperature) further comprises establishing and maintaining (110) the DPF inlet temperature between approximately three hundred degrees Celsius and approximately five hundred degrees Celsius. [5] Method (100) according to claim 4, wherein the conversion of NO in the exhaust gas entering the DOC (14) to NO2 with the DOC (14) further comprises a conversion (112) of NO in the exhaust gas entering the DOC (14) to NO2 with the DOC (14) using platinum as a catalyst. [6] Method (100) according to claim 5, comprising at least partially deactivating the first DEF injection device (18) and the upstream SCR (16) with the exhaust system controller (26) so that NO2 can pass through the upstream SCR (16), furthermore before increasing (108) levels of NO in exhaust gas from the engine (12), establishing and maintaining (110) a target DPF inlet temperature and a target DOC inlet temperature and converting NO in the exhaust gas entering the DOC (14) to NO2 with the DOC (14): at least partially deactivating (112) the first DEF injection device (18) with the exhaust system controller (26) and Allow residual DEF in the upstream SCR (16) to decrease to acceptable levels. [7] Method (100) according to claim 6, wherein the conversion of solid carbon-based particulate material that has accumulated in the DPF (20) into gaseous carbon dioxide (CO2) and NO using NO2 as an oxidizing agent further comprises: Exposure (114) of the carbon particle material in the DPF (20) to a platinum and / or a palladium catalyst, wherein the carbon particle material and the NO2 react to form CO2 and NO, and wherein furthermore the NO reacts with oxygen (O2) to form NO2, wherein the newly formed NO2 further reacts with carbon particle material. [8] Method (100) according to claim 7, further comprising: Monitoring (122) of a level of carbon particle material in the DPF (20) with the exhaust system controller (26) via communication with a delta pressure sensor (30F) and a temperature of the exhaust gas in the DPF (20); and Initiate (128) a short-term O2-based post-treatment regeneration of the DPF (20) when: a level of particulate material in the DPF (20) increases during an NO2-based post-treatment regeneration (126); or the level of particulate material in the DPF (20) decreases more slowly (130) than a predetermined rate during an NO2-based post-treatment regeneration. [9] Method (100) according to claim 8, wherein initiating a short-term O2-based post-treatment regeneration of the DPF (20) further comprises: Managing (140) the level of O2 in exhaust gas at the inlet (44) of the DPF (20) by controlling levels of O2 in exhaust gas from the engine (12) with the exhaust system controller (26) via communication with the engine controller (28) by selectively adjusting the use of the EGR unit (42), the injection timing, the injection quantity and the fresh air quantity in the engine (12) with the exhaust system controller (26) via communication with the engine controller (28), Establishing and maintaining (142) a desired EGT between approximately five hundred degrees Celsius and six hundred and fifty degrees Celsius at the inlet (44) of the DPF (20) by: Calculating (144) a target EGT of exhaust gas coming from the engine (12) and a target EGT of exhaust gas coming from the DOC (14) based on the desired EGT at the inlet (44) of the DPF (20) and the thermodynamic properties of the exhaust system (10), and Establishing and maintaining (146) the target EGT of exhaust gas coming from the engine (12) and the target EGT of exhaust gas coming from the DOC (14) by actively controlling combustion characteristics of the engine (12) with the exhaust system controller (26) via communication with the engine controller (28) and selectively utilizing late injections and post-injections in the engine (12) with the exhaust system controller (26) via communication with the engine controller (28); and Converting (148) solid, carbon-based particulate material that has accumulated in the DPF (20) into gaseous CO2 using O2 as an oxidizing agent. [10] The method (100) according to claim 9, further comprising initiating (134) a short-term SCR desulfurization and desorbing sulfur oxides (SOx) within the upstream SCR (16), wherein the short-term SCR desulfurization comprises: Establishing and maintaining (136) a target desorption EGT at an inlet of the upstream SCR (16) by: Calculating a target EGT of exhaust gas coming from the engine (12) and a target EGT of exhaust gas coming from the DOC (14) based on the target desorption EGT and the thermodynamic properties of the exhaust system (10); and Establishing and maintaining (138) the target EGT of exhaust gas coming from the engine (12) and the target EGT of exhaust gas coming from the DOC (14) by actively controlling combustion characteristics of the engine (12) with the exhaust system controller (26) via communication with the engine controller (28) and selectively utilizing late injections and post-injections within the engine (12) with the exhaust system controller (26) via communication with the engine controller (28).

Images