Emission control system and exhaust gas treatment process in a hybrid vehicle

Abstract

Emission control system (34) for exhaust gas treatment in a hybrid motor vehicle (10) with a NO x -generating internal combustion engine (26) and an electric motor (105), wherein both the internal combustion engine (26) and the electric motor (105) are designed to provide torque that is functionally coupled to a powertrain (106) of the vehicle (10), comprising the emission control system (34): a first electric heating device (208) which is functionally arranged in an exhaust pipe (204) which is functionally connected to the internal combustion engine (26), wherein the exhaust pipe (204) carries the exhaust gas (206); a first NO x -Storage catalyst (LNT device) (210) which is arranged in the exhaust pipe (204) downstream of the first electric heating device (208); a second LNT device (220) which is arranged in the exhaust pipe (204) downstream of the first LNT device (210); a passive selective catalytic reduction (SCR) device (230) arranged in the exhaust line (204) downstream of the second LNT device (220); a hydrocarbon oxidation catalyst device (240) arranged in the exhaust line (204) downstream of the passive SCR device (230); a second electric heating device (218) arranged in the exhaust pipe (204), wherein the second electric heating device (218) is designed to facilitate the regeneration of the second LNT device (220), the SCR device (230), and / or the hydrocarbon oxidation catalyst device (240); and a control unit (103) which is functionally connected to the first electric heating device (208), wherein the first NO x-Sensor (252a), the first temperature sensor (254a) and the controller (103) for executing a method for controlling the NO x -NO emissions x -generating internal combustion engine (26), the method encompasses: Monitoring a torque request for the vehicle (10); Determine if the torque demand is high enough to initiate combustion, NO x to generate an output that exceeds a preselected threshold; Operating the internal combustion engine (26) at a reduced torque that is lower than the torque requirement; and Operating the electric motor (105) with the internal combustion engine (26) to provide sufficient torque to meet the torque requirement, wherein the reduced torque in addition to the sufficient torque is equal to the torque requirement.

Description

[0001] This description relates to exhaust systems for internal combustion engines, and in particular to exhaust aftertreatment for electrified hybrid vehicles with a NO x -generating internal combustion engine, without injection of diesel emission fluid for emission control.

[0002] The exhaust gas emitted by an internal combustion engine, especially a diesel engine, is a heterogeneous mixture containing gaseous emissions such as carbon monoxide (CO), unburned hydrocarbons (HC) and nitrogen oxides (NO x) as well as condensed phase materials (liquids and solids) that constitute particulate matter (PM). Catalyst compositions, typically disposed on catalyst supports or substrates, are provided in an engine exhaust system as part of an aftertreatment system to convert some or all of these exhaust constituents into unregulated exhaust components. An exhaust treatment system typically includes one or more treatment devices, such as oxidation catalyst (OC) devices, selective catalytic reduction devices, particulate filters, mixing elements, and urea / fuel injectors. An oxidation catalyst device is provided in an exhaust system to treat unburned gaseous and non-volatile hydrocarbon (HC) and carbon monoxide (CO).The oxidation catalyst oxidizes the HC and CO under high temperature conditions to form carbon dioxide (CO2) and water (H2O).

[0003] Exhaust gas treatment systems also typically include selective catalyst reduction (SCR) devices. An SCR device includes a substrate, with an SCR catalyst arranged on it to reduce the amount of NO x in the exhaust gas. The typical exhaust treatment system also includes a reductant delivery system that injects a reductant, such as ammonia (NH3), urea (CO(NH2)2, etc.), typically known as diesel exhaust fluid (DEF). The SCR device uses NH3 in the DEF to reduce NO x For example, if NH3 is supplied to the SCR device under the appropriate conditions, the NH3 reacts with the NO x in the presence of the SCR catalyst to reduce the NO xHowever, reductant delivery systems can be cumbersome and costly to operate. Furthermore, they require maintenance and replenishment of the reductant.

[0004] DE 10 2011 101 079 A1 describes a process for the regeneration of nitrogen oxide storage catalysts and a correspondingly adapted exhaust gas purification system for lean-burn engines. In particular, the document refers to the regeneration of nitrogen oxide storage catalysts during special driving situations of the vehicle.

[0005] US 2017 / 0 167 346 A1 describes a method and a system for operating an aftertreatment system of an internal combustion engine. A storage efficiency value for the lean nitrogen oxide trap is determined. An exhaust gas temperature value is measured upstream of the lean nitrogen oxide trap. An activation condition for an electrically heated catalyst can be met if the storage efficiency of the lean nitrogen oxide trap is less than its threshold value and the exhaust gas temperature value upstream of the lean nitrogen oxide trap is greater than a lower threshold value and less than an upper threshold value. The electrically heated catalyst is activated when the enable condition is met. An inhibition activation condition can be met if the storage efficiency value is below a second threshold value, the electrically heated catalyst is deactivated, and denitrification of the lean nitrogen oxide trap is started.

[0006] US 2013 / 0 131 956 A1 describes a method for controlling a hybrid drive system with at least one electric motor and at least one diesel engine. The method corrects the static torque setpoint of the diesel engine and is carried out in the transition state as follows: Creating a nitrogen oxide (NO x ) emission model that allows the estimation of diesel engine emissions as a function of diesel engine torque; calculating a dynamic NO x -Emission target value from the NO x -emission model and from the static torque setpoint; determining a dynamic torque setpoint of the diesel engine from the NOx emission setpoint; determining a dynamic torque setpoint of the electric machine as a function of the static torque setpoint of the drive system and the dynamic torque setpoint of the diesel engine and applying the dynamic torque setpoints to the drive system.

[0007] DE 10 2016 200 972 A1 describes a method for controlling a drive train of a motor vehicle, which has an internal combustion engine and an electric machine which can be operated in the drive train as a generator and as a drive motor, as well as an energy storage device which absorbs and releases electrical energy, wherein an exhaust system of the internal combustion engine has a regenerable storage device for exhaust gas components and wherein a regeneration is only carried out when the internal combustion engine is operating in an operating range which is favorable for the regeneration, and wherein an operating point of the internal combustion engine which is outside the favorable operating range is shifted into the favorable operating range when a regeneration is carried out by operating the electric machine as a generator or as a drive motor.The method involves shifting the operating point during regeneration even if the operating point that would have been achieved without the shift is already within the favorable operating range. Furthermore, the implementation of the method by a control unit is described.

[0008] It can be considered as a task to provide an improved system and method for treating exhaust gases, whereby reducing agent supply systems are avoided and yet the limits for the emissions of an engine can be met.

[0009] The object is achieved by an emission control system according to claim 1 and a method for treating exhaust gas according to claim 8. According to the invention, an emission control system for treating exhaust gas in a hybrid motor vehicle with a NO x-generating internal combustion engine and an electric motor, wherein both the internal combustion engine and the electric motor are configured to provide torque operatively coupled to a powertrain of the vehicle. The emissions control system includes a first electric heater operatively disposed in an exhaust conduit operatively connected to the internal combustion engine, the exhaust conduit transporting exhaust gas, a first NO x-storage catalyst (LNT device) arranged in the exhaust conduit downstream of the first electric heater, and a second LNT device arranged in the exhaust conduit downstream of the first LNT. The emissions control system also includes a passive selective catalytic reduction (SCR) device arranged in the exhaust conduit downstream of the second LNT device, a hydrocarbon oxidation catalyst device arranged in the exhaust conduit downstream of the passive SCR device, and a second electric heater arranged in the exhaust conduit, wherein the second electric heater is configured to facilitate regeneration of at least one of the second LNT device, the SCR device, and the hydrocarbon oxidation catalyst device, and a controller operatively connected to the first electric heater, wherein the first NO x-Sensor, the first temperature sensor and the controller for executing a method for controlling the NO x -Emissions of NO x - generating internal combustion engine. The method performed by the controller includes monitoring a torque request for the vehicle, determining whether the torque request is large enough to cause combustion, NO x to generate a torque that exceeds a preselected threshold, operating the internal combustion engine at a reduced torque that is less than the torque request, and operating the electric motor with the internal combustion engine to provide sufficient torque to meet the torque request, wherein the reduced torque in addition to the sufficient torque is equal to the torque request.

[0010] In addition to one or more of the features described above, or alternatively, further embodiments may include a controller that executes a method that further determines whether regeneration of the first LNT device is required or in process, operates the internal combustion engine at a reduced preselected torque below the torque request, and operates the electric motor with the internal combustion engine to provide sufficient torque to meet the torque request, wherein the reduced preselected torque is equal to the torque request in addition to the sufficient torque.

[0011] In addition to one or more of the features described above, or alternatively, further embodiments may include that the reduced preselected torque is based on at least one of the operating conditions of the vehicle, an operating condition of the internal combustion engine, and the torque request.

[0012] In addition to one or more of the features described above, or alternatively, further embodiments may include that the reduced torque is based on at least one of the operating conditions of the vehicle, an operating condition of the internal combustion engine, and the torque request.

[0013] In addition to one or more of the features described above, or alternatively, further embodiments may include the first electric heating device being configured to facilitate regeneration of the first LNT device, the second LNT device, the passive SCR device, and / or the hydrocarbon oxidation catalyst device.

[0014] In addition to one or more of the features described above, or alternatively, further embodiments may include the second LNT device, the passive SCR device, and / or the hydrocarbon oxidation catalyst device comprising a particulate filter.

[0015] In addition to one or more of the features described above, or alternatively, further embodiments may include a temperature sensor operatively connected to the controller and in fluid communication with the exhaust gas.

[0016] In addition to one or more of the features described above, or alternatively, further embodiments may include a NO x -Sensor that is functionally connected to the control system and in fluid communication with the exhaust gas.

[0017] Also described according to the invention is a method for treating exhaust gases which are produced by a NO x -generating internal combustion engine in a hybrid vehicle with an electric motor, wherein both the internal combustion engine and the electric motor are configured to provide torque operatively coupled to a powertrain of the vehicle. The method includes operatively disposing a first electric heater in the exhaust gas carried through an exhaust conduit operatively connected to the internal combustion engine, operatively disposing a first NO x-storage catalyst (LNT device) in the exhaust conduit downstream of the first electric heater, the operative arrangement of a second LNT device in the exhaust conduit downstream of the first LNT device, the operative arrangement of a passive selective catalytic reduction (SCR) device in the exhaust conduit downstream of the second LNT device, the operative arrangement of a hydrocarbon oxidation catalyst device in the exhaust conduit downstream of the passive SCR device and the operative arrangement of a second electric heater in the exhaust conduit and facilitating the regeneration of the second LNT device, the SCR device and / or the hydrocarbon oxidation catalyst device with the second electric heater.

[0018] The method also includes operatively connecting a controller to the first electric heater, the controller being operable to perform a method for controlling the NO x -Emissions of NO x -generating internal combustion engine. The method performed by the controller includes monitoring a torque request for the vehicle, determining whether the torque request is large enough to cause combustion, NO x to generate a torque that exceeds a preselected threshold, operating the internal combustion engine at a reduced torque that is less than the torque request, and operating the electric motor with the internal combustion engine to provide sufficient torque to meet the torque request, wherein the reduced torque in addition to the sufficient torque is equal to the torque request.

[0019] In addition to one or more of the features described above, or alternatively, further embodiments may include a controller that executes a method that further determines whether regeneration of the first LNT device is required or in process, operates the internal combustion engine at a reduced preselected torque below the torque request, and operates the electric motor with the internal combustion engine to provide sufficient torque to meet the torque request, wherein the reduced preselected torque is equal to the torque request in addition to the sufficient torque.

[0020] In addition, the method may include the functions described above in connection with the emission control system as method steps. Fig. 1 shows an electrified motor vehicle with an internal combustion engine and an emissions control system according to one or more embodiments; Fig. 2 illustrates exemplary components of an emissions control system according to one or more embodiments; Fig. 3A shows a simplified expanded sectional view of a first LNT device with an integrated electric heater according to one or more embodiments; Fig. 3B shows a simplified perspective cross-sectional view of a first LNT device with an integrated electric heater according to one or more embodiments; Fig. 4A shows a simplified expanded sectional view of a second LNT / LNTF device with an integrated electric heater according to one or more embodiments; Fig. 4B shows a simplified perspective cross-sectional view of a second LNT / LNTF device with an integrated electric heater according to one or more embodiments; and Fig. 5 illustrates a flowchart of an illustrative method of controlling according to one or more embodiments.

[0021] This describes a novel exhaust aftertreatment system architecture that uses an electrically heated NO x-storage catalyst (LNT device) in conjunction with an innovative LNT on filter (LNTF) particulate filter. The system architecture also includes a passive selective catalytic reduction (SCR) catalyst and a hydrocarbon (HC) catalyst. Furthermore, an additional electric heater can optionally be used upstream of the filter to assist the regeneration of the second LNT under selected conditions. In some embodiments, implementations with additional heating elements can be weighted with regard to additional complexity and cost. Two LNTs connected in series with different efficiencies and temperature window efficiencies result in increased NO x-Performance of the entire aftertreatment and exhaust system over a wide temperature range. An e-heated LNT supports the system during low-load operation and after a cold start, e.g., in the first 500 seconds after engine start, where the exhaust temperature is maintained for effective NO x -Conversion is still too low.

[0022] Advantageously, the arrangement results in a completely passive system, thus eliminating the need for reductant dosing, e.g., diesel exhaust fluid (DEF) injection, as is common in diesel aftertreatment. The architecture of the described embodiments is optionally implemented in a fully enclosed, coupled, integrated configuration with innovative packaging that, among other things, would utilize the higher engine outlet temperatures for improved catalyst performance.

[0023] The described aftertreatment system uses a LNTF that provides a simultaneous and continuous reduction of particulate matter (PM) and nitrogen oxide (NO x ) emissions. The LNT coating in a particulate filter application works with regard to NO x conversion as in conventional systems. In addition, under lean operating conditions, PM is removed by active oxygen, which is present in the NO x storage process and oxidized by excess oxygen in the exhaust gas. Under rich conditions, PM is also oxidized by the active oxygen released in the reduction process of stored NO x Therefore, PM and NO x reduced by regulating the air-fuel ratio alternately from lean to rich.

[0024] It should be noted that electrically heated LNT and LNTF technologies have previously been investigated in a variety of aftertreatment configurations (i.e., different aftertreatment layouts and components). Unfortunately, none have proven commercially successful, as both technologies present various drawbacks, trade-offs, and challenges. However, the disclosed configuration and methodology facilitate the implementation of ultra-low-emission combustion and electrification technologies, which represent a viable option, with advantages in terms of aftertreatment costs and packaging.

[0025] A motor vehicle according to one aspect of an embodiment is generally shown at 10 in Fig. 1. In particular, the vehicle 10 is a hybrid-electric vehicle, in particular a diesel-electric hybrid vehicle 10. Fig. 1 is a vehicle schematic illustrating the components of the subject vehicle 10 with respect to the disclosed principles and the manner in which the components may be interconnected to carry out those principles. It should be understood, however, that the illustrated architecture is merely an example, and that the disclosed principles do not require the vehicle 10 to be configured as illustrated. It should be understood that the motor vehicle 10 may take various forms, including automobiles, commercial vehicles, vessels, etc. The motor vehicle 10 includes a body 12 and a passenger compartment 15. In some embodiments, the motor vehicle 10 may also include an engine compartment 14 in which a propulsion system 100 is located, in whole or in part.In some embodiments, the engine compartment 14 houses an internal combustion engine (ICE) system, generally shown at 20, which in some cases may be part of a hybrid implementation of the propulsion system 100. The internal combustion engine system 20 may also include a transmission (not shown) mechanically coupled to a drivetrain 106. It should be noted that the technical solutions described herein are relevant to ICE systems 20, which may include, but are not limited to, diesel engine systems and gasoline engine systems. The ICE system 20 may include a plurality of reciprocating pistons attached to a crankshaft, which may be operatively attached to a propulsion system, such as a vehicle propulsion system, to propel a vehicle (e.g., to provide traction torque to the propulsion system).For example, the ICE system 20 may be any engine configuration or application, including various vehicle applications (e.g., automotive, marine, and the like) as well as various non-vehicle applications (e.g., pumps, generators, and the like). The ICE system 20 includes an exhaust system 30 (. Fig. 2), which is fluidly connected to an aftertreatment or emissions control system 34. The exhaust gas produced by the ICE system 20 flows through the emissions control system 34 to reduce emissions that may escape to the environment through an exhaust outlet pipe (not shown).

[0026] Although the ICE system 20 may be described in a vehicle-related context (e.g., torque-generating), other non-vehicle-related applications are within the scope of this description. Therefore, when reference is made to a vehicle, this description should be interpreted as applying to any application of an ICE system 20. Furthermore, an ICE system 20 may generally represent any device capable of generating an exhaust stream containing gaseous (e.g., NO x, O2) carbonaceous and / or particulate species, and the description herein should accordingly be considered applicable to all such devices. As used herein, "offgas" refers to any chemical species or mixture of chemical species requiring treatment and including gaseous, liquid, and solid species. For example, an offgas stream may contain a mixture of one or more NO xspecies, one or more liquid hydrocarbon species, and one or more solid particulate species (e.g., ash). It should also be understood that the embodiments disclosed herein may be applicable to treating exhaust streams that do not include carbonaceous and / or particulate substances, and in these cases, the ICE system 20 may also generally represent any device capable of generating a exhaust stream that includes such substances. Exhaust particulate matter generally includes carbonaceous soot and other solid and / or liquid carbonaceous species relevant to the ICE system 20 or formed in an emissions control system 34.

[0027] In further embodiments, the ICE system 20 may be configured to power an electric propulsion system in a hybrid configuration. For example, in one embodiment, the ICE system 20 provides electrical energy for operating an electric propulsion system 100. In some embodiments, the propulsion system 100 and the ICE system 20 may be mechanically coupled to a powertrain 106 to propel the vehicle 10 (e.g., to provide traction torque to the powertrain 106).

[0028] Furthermore, an ICE system 20 may generally represent any device capable of producing an exhaust stream containing gaseous (e.g., NO x , O2) includes carbonaceous and / or particulate species, and the description herein should accordingly be considered applicable to all such devices.

[0029] As used herein, "offgas" refers to any chemical species or mixture of chemical species requiring treatment and includes gaseous, liquid, and solid species. For example, an offgas stream may contain a mixture of one or more NO xspecies, one or more liquid hydrocarbon species, and one or more solid particulate species (e.g., ash). It should also be understood that the embodiments disclosed herein may be applicable to treating exhaust streams that do not include carbonaceous and / or particulate substances, and in these cases, the ICE system 20 may also generally represent any device capable of generating a exhaust stream that includes such substances. Exhaust particulate matter generally includes carbonaceous soot and other solid and / or liquid carbonaceous species relevant to the ICE system 20 or formed in an emissions control system 34.

[0030] In continuation of Fig. 1, the vehicle 10 and the drive system 100 in the illustrated example include an electrical energy storage system 101 (e.g., a battery or battery bank (battery)) with a suitable voltage and capacity. Suitable battery types include lead-acid batteries, nickel-cadmium batteries (NiCd), nickel-metal hydride batteries (NiMH), lithium-ion batteries, and lithium-polymer batteries. The electrical energy storage system 101 is conductively connected, for example, via a motor controller 103, to an electric drive unit 105, e.g., one or more electric motors (hereinafter, electric motor 105). It should be noted that the electrical output of the electrical energy storage system 101 may be modulated, voltage-modified, or otherwise modified by the motor controller 103 (or other devices) if necessary to drive the electric motor 105.In some embodiments, the motor controller 103 may include a motor drive system 104. In other embodiments, a separate motor drive system 104 may be used. Typically, a motor drive system 104 may include a voltage converter, an inverter, and transient filtering selection as commonly used. The electric motor 105 is connected or connectable to a ground-based drive, typically including one or more wheels 107. In some embodiments, the electric motor 105 is a single electric motor operatively connected to the driveline 106, while in other cases, multiple electric motors 105 may be used to drive an axle or wheel 107 of the vehicle 10. For clarity, a single motor 105 coupled to a single axle 108 is shown, however, a variety of configurations are possible.

[0031] In an optional implementation, a plug-in interface 109 may be provided to charge the electrical energy storage system 101, although it should be noted that the teachings herein also apply to vehicles with plug-in architectures. The plug-in interface enables the drive system 100 and the motor drive system 104 to connect to an AC / DC power source, such as an electrical main (e.g., 115 / 230 volts AC, e.g., via the plug-in interface 109), a power bus, a DC bus (e.g., a battery 101), and the like. The plug-in interface 109 is connected to the electrical energy storage system 101 via a charging controller 111.An optional aspect of the vehicle 10 and the electrical energy storage system 101 is the ability to electrically isolate the electrical energy storage system 101 from the rest of the vehicle 10 by controlling at least one, preferably two or more, high-voltage contactors 113 when an adverse condition is detected. A communication interface 114 may also be used and adapted to receive information from the charging controller 111 or the engine controller 103 and to transmit data relating to the vehicle 10, the propulsion system 100, and the battery 101 to a remote system 110. In a further embodiment, the engine controller 103 and the charging controller 111 may be connected to a control module 260 (. Fig. 2) for the emissions control system 34. Furthermore, one or all of the controllers 111, 103, or the control module 260 may further include control functions for controlling the operation of the vehicle 10. In one embodiment, the engine controller 103 provides functions for controlling the functionality of the vehicle 10 and the propulsion system 100. In one embodiment, the remote system 110 may be a server configured to receive vehicle status, maintenance, or fault information, and the like. For example, in one embodiment, the communication interface 114 provides the remote system 110 with the engine status, state of charge, and operating state of the system connected to the electrical energy storage system 101.The drive system 100 as described is described with respect to a drive system for a motor vehicle 10, wherein application may be provided to any system in which a control of a motor drive system 104 is used.

[0032] Fig. Figure 2 illustrates exemplary components of the emissions control system 34 according to one or more embodiments. It should be noted that while the ICE system 20 in the above example includes a diesel engine 26, the emissions control system 34 described herein may be implemented in various engine systems, particularly in any NO x -generating internal combustion engine. The emission control system 34 facilitates the control and monitoring of NO xStorage and / or treatment materials to control the exhaust gases generated by the ICE system 20. For example, the technical solutions herein include methods for controlling electrical heating elements, NO x -Storage catalysts (LNT device), selective catalytic reduction (SCR) devices and associated NO x , temperature and pressure sensors, wherein the LNT devices, SCR devices are designed to receive exhaust streams from an exhaust source. As used herein, "NO x “ to one or more nitrogen oxides. NO x Substances can N y O x Include substances where y>0 and x>0. Non-limiting examples of nitrogen oxides may include NO, NO2, N2O, N2O2, N2O3, N2O4, and N2O5. SCR devices are configured to accept reductants, for example, at variable dosing rates, as described below.

[0033] In continuation of Fig. 2, an exhaust conduit 204, which may include multiple segments, transports the exhaust gas 206 from diesel engine 26 to the various exhaust treatment devices of emissions control system 34. For example, as shown, emissions control system 34 includes a series connection of a first heater 208 with a first LNT device 210. An optional second heater 218 is deployed upstream of a second LNT device 220, which then routes the exhaust gases to a passive SCR device 230. In one or more examples, second LNT device 220 may include a selective catalytic filter (SCRF) device that provides the catalytic aspects of SCRs in addition to particulate filtering capabilities. In one or more examples, SCR device 230 may include a selective catalytic filter (SCRF) device that provides the catalytic aspects of SCRs in addition to particulate filtering capabilities.The emissions control system 34 may include various additional treatment devices, including, but not limited to, diesel oxidation catalyst (DOC) devices 240 and additional particulate filter devices (not shown).

[0034] In continuation of Fig. 2, the first heater 208 is disposed in the exhaust stream 206 upstream of the first LNT device 210. In one embodiment, the first heater 208 and the first LNT device 210 are disposed within a housing 212 that substantially encloses the first heater 208 and the substrate 214 of the first LNT 210. The substrate 214 may be made of metal, but other materials are also possible. The housing 212 may be generally cylindrical or any other shape that allows the flow of exhaust 206 from an inlet 213 to an outlet 215 and through the substrate 214. The inlet 213 provides the fluid passage for the exhaust stream 206 into the first heater device 208 and the first LNT device 210, and the outlet 215 provides the fluid passage for the exhaust stream 206 from the substrate device 214.

[0035] Now to Fig. 3A and Fig. 3B, with further reference to Fig. 2, the first LNT device 210 includes a first electrode 216 electrically connected to a power source on the vehicle 10 by a first transmission wire (not shown). The first electrode 216 extends through the housing 212 of the first LNT device 210 and contacts the first heater 208. A second electrode 217 extends from the housing 212 of the first LNT device 210 and is also electrically connected as needed to complete the electrical circuit in a conventional manner. While the second electrode 217 extends from the housing 212, it is also possible for the second electrode 217 to be in contact with the first heater 208 generally opposite the first electrode 216. When current is supplied to the first electrode 216, the current is isolated from the housing 212 and the current is supplied to the first heater 208 of the first LNT device 210, exiting the second electrode 217.In one embodiment, the electrodes 216, 217 and portions of the heater 208 may be a portion of the first LNT device 210. In further embodiments, the first heater 208 is a separate heater from the substrate 214 of the first LNT device 210. It is also possible for the heater 208, which is all or part of the substrate 214, to be configured to generate heat upon application of an electric current. It is possible for the selective introduction of current to the first LNT device 210 to occur upon user activation or upon automatic activation, such as by an engine controller 103 or an emissions control system 34, including a control module 260.

[0036] When current flows through the first heating element 208, heat is generated in the first LNT device 210. The exhaust gases 206 flowing through the first LNT device 210 are heated via the heater 208, and the heated exhaust gases 206 flow to / through the substrate 214. The first heater 208 provides sufficient heat to the exhaust gases 206 to initiate an efficient reaction in the substrate 214 and the regeneration of the filter media as described herein, if needed. Furthermore, electrically heating the exhaust gases 206 facilitates the regeneration of the first LNT device 210 by providing more desirable temperatures for regeneration.

[0037] In operation, the first heater 208 is controlled by a control module 260. In one embodiment, the control module 260 executes a method that controls the operation of the ICE system 20, and in particular, the temperatures and NO x-content of the exhaust gases 206 is monitored. The first heater 208 is used to heat the exhaust gases 206 to ensure reaction with the catalyst on the substrate 214 as described herein. Furthermore, the control module 260 may further use the first heater 208 for additional applications, including assisting in the regeneration of the catalyst on the substrate 214 of the first LNT device 210 and / or the second LNT / LNTF device 220. Finally, it should be noted that while the primary function of the first heater 208 is aftertreatment warm-up (e.g.,heating the components of the emission control system 34 to operating temperature, particularly during start-up), while the first heating device 208 also allows the emission control system 34 to increase the temperature after the first LNT device 210 is turned off in order to perform purge / regeneration in a more efficient temperature window for both the NO. x -conversion as well as for NH3 production.

[0038] As can be seen, the first LNT device 210 may consist of various flow-through oxidation catalyst devices known in the art. In various embodiments, the first LNT device 210 may include a flow-through metal or ceramic monolith substrate 214. The substrate 214 may be packaged within the envelope or canister, which, as described above, forms a housing 212 and is in fluid communication with the exhaust gas 206 in the exhaust conduit 204. The substrate 214 may have a NO x -adsorption compound. The NO x The adsorption compound can be applied as a washcoat and can contain zeolites, alkali / alkali oxide (carbonate), or combinations and compounds thereof. The first LNT device 210 is useful in storing and treating the nitrogen oxides present in the exhaust gas 206. Under lean operating conditions, the NO xaccumulated or "trapped" in the substrate 214 of the LNT device 210, 220. The trapped NO x is periodically released or "purged" by operating at a stoichiometric or rich air-fuel ratio. The released NO x is reduced to N2 by reducing agents in the exhaust gas 206, such as CO and H2. The possible reaction mechanisms during the storage and purge phases of the LNT devices 210, 220 are known. Under lean conditions, NO is oxidized to NO2 in the gas phase over platinum. The resulting NO2 is adsorbed on an oxide surface as nitrate (e.g., as barium nitrate for a barium adsorbent). Typical adsorbents for the LNT substrate include oxides of potassium, calcium, cerium, zirconium, lanthanum, and barium.

[0039] The sequence of steps and reactions is as follows: Nitrate decomposition: Ba(NO3) + 2 CO → NO + 2 CO2 NO conversion: 2 NO + 2 CO → N2 + 2 CO2

[0040] At rich air-fuel ratios for the ICE 20, the adsorbed barium nitrate from the LNT device (e.g., 210, 220) is released as barium oxide. In the presence of reducing agents (also in the exhaust gas 206), such as CO, HC, and H2, and a Pt / Rh catalyst, the NO x into nitrogen and the deposition component, with barium carbonate being recovered to form H2, CO2, H2O and NH3.

[0041] The order of steps to the remaining reactions are: CO + H2O → CO2 + H2 5 H2 + 2 NO → 2 NH3 + 2 H2O HC + H2O → CO + 3 / 2 H2

[0042] Advantageously, the NH3 is passed into the remaining exhaust gas 206 and to the SCR device 230, where it is captured, stored and used as a reducing agent for further NO x-reduction, as explained in more detail herein. It should also be noted that the sulfur present in the fuel acts as a poisoning agent. That is, during the combustion process, the sulfur is oxidized to sulfur dioxide (SO2). The sulfur dioxide is oxidized to sulfur trioxide in the presence of platinum. The sulfur oxide is retained as barium sulfate under the operating conditions of the trap. As a result, the NO xThe capture efficiency of the LNT device 210 is a function of the capture temperature, catalyst loading, fuel sulfur content, space velocity, feed gas concentration, and capture device regeneration frequency. It has also been found that using a richer A / F ratio for purging allows the LNT device(s) 210, 220 to operate for a longer period of time. However, purging with a richer ratio not only has a greater impact on fuel consumption but also increases the likelihood that the trapped sulfate will be converted to unwanted hydrogen sulfide, which must also be treated and not released. It is clear that to improve fuel consumption and minimize NO x emissions, the storage and purge control strategy for the LNT device(s) 210, 220 must be well designed and optimized.

[0043] A washcoat layer includes a compositionally distinct material layer disposed on the surface of the monolithic substrate 214 or an underlying washcoat layer. A catalyst may include one or more washcoat layers, and each washcoat layer may have unique chemical catalytic functions. In the first LNT device 210, the catalyst compositions for the nitrogen storage function may be disposed in discrete washcoat layers on the substrate 214, or alternatively, the compositions for the first LNT device 210 and NO x -Memory functions may be present in discrete longitudinal zones on the substrate 214.

[0044] The substrate body 214 for the first LNT device 210 may, for example, be a ceramic brick, a plate structure, or any other suitable structure, such as a monolithic honeycomb structure containing several hundred to several hundred parallel flow cells per square inch, although other configurations are suitable. Each of the flow cells may be defined by a wall surface onto which the catalyst composition may be washcoated. The substrate body 214 may be formed from a material capable of withstanding the temperatures and chemical environment associated with the exhaust gas 206.Some specific examples of materials that can be used include ceramics such as extruded cordierite, α-alumina, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica-magnesia, zirconium silicate, sillimanite, petalite, or a heat- and corrosion-resistant metal such as titanium or stainless steel. The substrate can, for example, comprise a non-sulfating TiO2 material. The substrate body can also serve as a particulate filter, as explained below.

[0045] The LNTF catalyst compositions are generally a porous material with a larger surface area that can work efficiently to produce NO x-components of the exhaust gas 206. Suitable LNT catalyst compositions can exhibit high thermal structural stability, particularly when used in tandem with particulate filter (PF) devices or when integrated into the LNTF devices described below that are regenerated using high-temperature soot combustion processes. The LNT catalyst composition can optionally also comprise one or more basic metal oxides as promoters to further reduce SO3 formation and extend catalyst life. The one or more basic metal oxides can include WO3, Al2O3, and MoO3 in some embodiments. In one embodiment, WO3, Al2O3, and MoO3 can be used in combination with V2O5.

[0046] In continuation of Fig. 2, the exhaust gas 206 is routed after the first heater 208 and the first LNT 210 to the optional second heater 218, which is disposed in the exhaust stream 206 upstream of the second LNT device 220. In one embodiment, the optional second heater 218 and the second LNT device 220 are disposed in the housing 222. The second LNT device 220 operates in a manner similar to the first LNT device 210 described herein. Consequently, for simplicity, further explanation of the operation of the second LNT device 220, which is similar to the first LNT device 210, is omitted.

[0047] In one embodiment, the second LNT device 220 is also an LNT on filter, also referred to as LNTF and identified by the reference numeral 220. In at least one embodiment, the filter portion 229 of the substrate 224 is configured as a particulate filter (PF), such as a diesel particulate filter (DPF). As previously mentioned, the substrate 224 of the second LNT / LNTF device 220 may be made of metal, but other materials are also possible. The housing 222 may be generally cylindrical or any other shape that allows the flow of exhaust gas 206 from an inlet 223 to an outlet 225 and through the substrate 224. The inlet 223 provides the fluid passage for the exhaust stream 206 into the optional second heater device 218 and the first LNT / LNTF device 220, and the outlet 225 provides the fluid passage for the exhaust stream 206 from the substrate device 224. The filter section 229 (ieFor example, the PF) of the substrate 224 may be constructed with a monolithic ceramic wall-flow exhaust filter substrate configured to filter or trap carbon and other particulates from the exhaust gas 206. It should be understood that a ceramic wall-flow monolith filter substrate is merely exemplary in nature and that the filter portion 229 of the substrate 224 may include other filter devices such as wound or packed fiber filters, open-cell foams, sintered metal fibers, etc. The emissions control system 34 may also perform a regeneration process that regenerates the substrate 224 by burning off the particulates trapped in the filter portion 229 of the substrate 224, in one or more examples.

[0048] Now to Fig. 4A and Fig. 4B and again to the first electrode 226 of the second heater 218, which is electrically connected to a power source on the vehicle 10 by a first transmission wire (not shown). The first electrode 226 extends through the housing 222 of the second LNT / LNTF device 220 and contacts the second heater 218. A second electrode 227 extends from the housing 222 of the second LNT / LNTF device 220 and is also electrically connected as needed to complete the electrical circuit in a conventional manner. While the second electrode 227 extends from the housing 222, it is also possible for the second electrode 227 to be in contact with the second heater 218 generally opposite the first electrode 226.When current is supplied to the first electrode 226, the current is isolated from the housing 222 and the current is supplied to the second heater 218 of the second LNT / LNTF device 220, exiting from the second electrode 227. As described herein, for the first heater 208 and the first LNT device 210, in one embodiment, the electrodes 226, 227 and all or a portion of the second heater 218 may be part of the second LNT / LNTF device 220. In another embodiment, the second heater 218 is a separate heater from the substrate 224 of the second LNT / LNTF device 220. It is also possible for the heater 208, which is all or a portion of the substrate 224, to be configured to generate heat upon application of an electric current.Again, it is possible that the selective introduction of current to the second LNT / LNTF device 220 may occur upon user activation or automatic activation, such as by an engine control or emissions control system 34.

[0049] As current flows through the second heater 218, heat is generated in the second LNT / LNTF device 220. The exhaust gases 206 flowing through the second LNT / LNTF device 220 are heated by the second heater 218, and the heated exhaust gases 206 flow to / through the substrate 224. The second heater 218 provides sufficient heat to the exhaust gases 206 to initiate, if necessary, an efficient reaction of the catalyst on the substrate 224 and the regeneration of the filter media as described herein. Furthermore, the electrical heating of the exhaust gases 206 provides desirable temperatures for the regeneration of the second LNT / LNTF device 220, as well as for purging the particulate filters (e.g., 229) aspects of the second LNT / LNTF device 220.

[0050] In continuation of Fig. 2, during operation, the second heater 218 is also controlled by the control module 260. In one embodiment, the control module 260 executes a method that controls the operation of the ICE system 20 and in particular the temperatures and NO x-content of the exhaust gases 206 is monitored. The optional second heater 218 serves to further heat the exhaust gases 206 to ensure the reaction described herein. In addition, the control module 260 may further utilize the optional second heater 218 for additional applications, including assisting in the regeneration of the catalyst on the substrate 224 of the second LNT / LNTF device 220. Finally, it should be noted that while the primary function of the second heater 218 is post-treatment heating, e.g., maintaining / maintaining the components of the emission control system, and in particular the second LNT / LNTF device 220, at operating temperature, especially during startup, the second heater 218 also provides the emission control system 34 with the ability to increase the temperature after the second LNT / LNTF device 220 is shut down, both for NO xconversion and NH3 production in a more efficient temperature window over rich operating conditions to perform the regeneration of the ICE system 20. Furthermore, in a filter configuration, the second heater 218 also operates to combust / purge particulates from the filter portion 229 of the substrate 224 using high-temperature combustion cycles.

[0051] It is further understood that while the emission control system 34 as shown in Fig. 2, with the first electric heater 208 located upstream of the first LNT device 210, it is possible that when the exhaust gas 206 reaches a sufficient exhaust temperature, the emissions control system 34 may include only a single LNT device 210, with or without the integrated first heater 208 and substrate / catalyst 214, and no subsequent ones, e.g., the second heater 218 or second LNT / LNTF device 220. Likewise, when two heaters are described, it is possible that more than one heater may be employed if necessary to increase the temperature of the exhaust gas 206 and ensure the efficient operation of the emissions control system 34.

[0052] In continuation of Fig. 2, after leaving the second LNT / LNTF device 220, the exhaust gases 206 are then directed to an SCR device 230. The SCR device 230 may, for example, include a flow-through ceramic or metal monolith substrate 234 that may be packaged in a shell or container 232 having an inlet 233 and an outlet 235 in fluid communication with the exhaust conduit 204 and optionally other exhaust treatment devices, e.g., the first LNT device 210, the second LNT / LNTF device 220, and the like. The shell or container 232 may ideally comprise a material that is largely inert to the exhaust constituents, such as stainless steel. The substrate 234 may include an SCR catalyst compound applied thereto.

[0053] The substrate 234 may, for example, be a ceramic brick, a plate structure, or any other suitable structure, such as a monolithic honeycomb structure containing several hundred to several thousand parallel flow cells per square inch, although other configurations are suitable. Each of the flow cells may be defined by a wall surface onto which the catalyst composition may be washcoated. The substrate 234 may be formed from a material capable of withstanding the temperatures and chemical environment associated with the exhaust gas 206. Some specific examples of materials that may be used include ceramics such as extruded cordierite, α-alumina, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica-magnesia, zirconium silicate, sillimanite, petalite, or a heat- and corrosion-resistant metal such as titanium or stainless steel.The substrate may, for example, contain a non-sulfating TiO2 material. The substrate body may also serve as a particle filter, as explained below.

[0054] The SCR catalyst compositions are generally a porous material with a large surface area that can work efficiently to remove NO xconstituents in the exhaust gas 206 in the presence of a reducing agent, such as ammonia. For example, the catalyst composition may include a zeolite and one or more base metal components, such as iron (Fe), cobalt (Co), copper (Cu) or vanadium (V), sodium (Na), barium (Ba), titanium (Ti), tungsten (W), and combinations thereof. In a particular embodiment, the catalyst composition may include a zeolite impregnated with one or more of copper, iron, or vanadium. In some embodiments, the zeolite may be a β-zeolite, a Y-zeolite, a ZM5 zeolite, or any other crystalline zeolite structure, such as a chabazite or a USY (ultrastable Y-type) zeolite. In a particular embodiment, the zeolite comprises chabazite. In a particular embodiment, the zeolite comprises SSZ.Suitable SCR catalyst compositions can exhibit high thermal structural stability, particularly when used in tandem with particulate filter (PF) devices or when integrated into the SCRF devices described below that are regenerated using high-temperature soot combustion processes. The SCR catalyst composition can optionally also comprise one or more basic metal oxides as promoters to further reduce SO3 formation and extend catalyst life. The one or more basic metal oxides can, in some embodiments, include WO3, Al2O3, and MoO3. In one embodiment, WO3, Al2O3, and MoO3 can be used in combination with V2O5.

[0055] The SCR device 230 may be disposed downstream of the first LNT device 210 and the second LNT / LNTF device 220. In one embodiment, the SCR device 230 is a passive device. In one or more examples, the SCR device 230 receives and stores reductant, i.e., NH3, released from the first LNT device 210 or the second LNF / LNTF device 220 that is present in the exhaust gases 206. The catalyst, which includes a washcoat coating disposed on the substrate 234, stores the NH3 in the exhaust gases 206 to produce NO x -components therein. The SCR device 230 uses the excess ammonia (NH3) to further react with the remaining NO x in the exhaust gases 206 passing the first LNT 210 or the second LNT / LNTF device 220 (ie, NO x -slip) have happened.

[0056] The SCR device 230 includes an SCR catalyst that generally uses a reductant, e.g., excess NH3 or NH3 compounds exhausted from the first LNT device 210 or the second LNT device 220, to produce NO x species (e.g. NO and NO2) to unregulated emission components. These components include, for example, one or more species that do not contain NO x species, diatomic nitrogen, nitrogen-containing inert species, or species considered acceptable emissions. It should be noted that in one embodiment, the reductant is typically ammonia (NH3) as emitted by the first LNT device 210 and the second LNT / LNTF device 220, but may also be any compound produced by the first LNT device 210 or the second LNT device 220 that is capable of reacting with NO in the presence of exhaust gas 206 and / or heat.x to decompose or react. Equations (1) - (5) provide exemplary chemical reactions for NO x -Reduction with ammonia. 6NO + 4NH3 → 5N2 + 6H2O (1) 4NO + 4NH3+ O2 → 4N2 + 6H2O (2) 6 NO2 + 8 NH3 → 7 N2 + 12 H2O (3) 2 NO2+ 4 NH3 + O2 → 3 N2 + 6 H2O (4) NO + NO2 + 2 NH3 → 2 N2+ 3 H2O (5)

[0057] It is understood that equations (1) - (5) are merely illustrative and are not intended to limit the SCR device 230 to a particular NO x reduction mechanism or mechanisms, nor to preclude the operation of other mechanisms. The SCR device 230 may be configured to perform one of the above-mentioned NO x -Reduction reactions, combinations of the above NO x -Reduction reactions and other NO x-reduction reactions. Typically, an active SCR device is used with injected reductant into the exhaust gases. The injected reductant stored in the SCR device reacts with the NO x in the exhaust gases. In the described embodiments, a passive SCR device 230 is used. The passive SCR device 230 stores reductants present in the exhaust gases 206 resulting from the reactions in the first LNT device 210 or the second LNT / LNTF device 220.

[0058] The SCR catalyst can store (i.e., absorb and / or adsorb) NH3 for interaction with the exhaust gas 206. A given SCR device 230 has a reductant capacity, or an amount of reductant or reductant derivative that can be stored. The amount of reductant stored within an SCR device 230 relative to the reductant storage capacity is often referred to as a "reductant loading" and can be expressed as a % loading (e.g., 90% reductant loading). During operation of the SCR device 230, the reductant is stored by the catalyst of the SCR device 230 and used in reduction reactions with NO x-species are consumed, requiring continuous replenishment. The replenishment results from the reactions in the first LNT device 210 and / or the second LNT / LNTF device 220. Controlling the operation of the first LNT device 210 and / or the second LNT / LNTF device 220 ensures that sufficient reductant storage levels are maintained in the SCR device 230 to facilitate maintaining exhaust emissions at an acceptable level. As previously mentioned, insufficient reductant storage levels in the SCR device 230 can result in NO x -breakthrough while excessive reductant fails to react through the SCR device 230 or exits as reductant slip.

[0059] In continuation of Fig. 2, the exhaust gases 206 exiting the SCR device 230 may then be routed to the hydrocarbon catalyst (OC / DOC) device 240, which in turn may optionally also include a particulate filter device (not shown). As can be appreciated, the DOC device 240 may be comprised of various flow-through oxidation catalyst devices known in the art. In various embodiments, the DOC device 240 may include a flow-through metal or ceramic monolith substrate 244. The substrate 244 may be packaged in a stainless steel canister or housing 242 having an inlet 243 and an outlet 245 in fluid communication with the exhaust conduit 204. The substrate 244 includes an oxidation catalyst compound disposed thereon.The oxidation catalyst compound may be applied as a washcoat and may include platinum group metals such as platinum (Pt), palladium (Pd), rhodium (Rh), or other suitable metal oxide catalysts and combinations thereof. The DOC device 240 is useful for treating unburned gaseous and non-volatile HC and CO, which oxidize to form carbon dioxide and water. A washcoat layer includes a compositionally distinct material layer disposed on the surface of the monolithic substrate 244 or an underlying washcoat layer. A catalyst may include one or more washcoat layers, and each washcoat layer may exhibit unique chemical catalytic functions.In the DOC device 240, the catalyst compositions for the oxidizing function may be located in discrete washcoat layers on the substrate 244, or alternatively, the compositions for the hydrocarbon oxidizing functions may remain in discrete longitudinal zones on the substrate 244.

[0060] In one or more examples, the emissions control system 34 further includes the control module 260 operatively connected via a number of sensors to monitor the engine 26 and / or the exhaust emissions control system 34. For example, the control module 260 may implement the control process described herein for overall emissions control, including NO xReduction and hydrocarbon oxidation, including the regeneration of substrates 214, 224, 234, and 244, respectively. The control module 260 may be operatively connected to the ICE system 20, the first LNT device 210, the second LNT / LNTF device 220, the SCR device 230, and the HC / DOC device 240 via one or more sensors 250. In one embodiment, the control module 260 is part of the controller 111 or the engine controller 103 ( Fig. 1). In another embodiment, the control module 260 may be a standalone component. As illustrated, the sensors, generally shown as 250, may detect a first NO x -Sensor 252a, which is arranged upstream of the first LNT device 210, a second NO x sensor 252b located upstream of the second LNT / LNTF device 220, and a third NO xsensor 252c, which is arranged upstream of the SCR device 230. In addition, a fourth NO x sensor 252d is inserted downstream in the exhaust gases 206 of the SCR device 230. Finally, a fifth NO x -Sensor 252e may be used downstream of the HC oxidizer / DOC device 240. Each of the NO x -Sensors 252a, 252b, 252c, 252d and 252e are in fluid communication with the exhaust gas 206 in the exhaust line 204. The NO x -Sensors 252a-e detect the NO x -level near their position and generate NO x -Signals that indicate the detected NO x -values. A NO x -Level may, in some embodiments, include a concentration, a mass flow rate, or a volumetric flow rate. A NO x -Sensor 252a-e generated NO x-Signal is transmitted to the control module 260 and can be interpreted by the control module 260 as needed for operation of the emissions control system 34.

[0061] The control module 260 may additionally communicate with one or more temperature sensors, such as a first temperature sensor 254a located upstream of the first LNT device 210. A second temperature sensor 254b is located upstream of the second LNT / LNTF device 220, while a third temperature sensor 254c is located upstream of the SCR device 230. Furthermore, a fourth temperature sensor 254d is located downstream of the SCR device 230. Finally, a fifth temperature sensor 254e is located downstream of the HC oxidation / DOC device 240. Each of the temperature sensors 254a, 254b, 254c, 254d, and 254e is in fluid communication with the exhaust gas 206 in the exhaust conduit 204. The temperature sensors 254a-e sense temperatures near their positions and generate temperature signals corresponding to the sensed temperatures.A temperature signal generated by a temperature sensor 254a-e is transmitted to the control module 260 and may be interpreted by the control module 260 as needed for operation of the emissions control system 34.

[0062] The sensors of the emissions control system 34 may further include at least one pressure sensor 256 (e.g., a delta pressure sensor). The delta pressure sensor 256 may determine the pressure differential (i.e., Δp) across the second LNT / LNTF device 220 or SCR device 230, depending on the configuration of the emissions control system 34. Generally, pressure sensors 256 are employed on the device to provide particulate filtration. In one embodiment, the pressure sensors are illustrated on the SCR device 230, with the description also being applicable to the second LNT / LNTF device 220. Additionally, although a single delta pressure sensor 256 is illustrated, it should be understood that a plurality of pressure sensors may be used to determine the pressure differential of the SCR device 230.For example, a first pressure sensor (not shown) may be disposed at the inlet 233 of the SCR device 230, and a second pressure sensor (also not shown) may be disposed at the outlet 235 of the SCR device 230. Accordingly, the difference between the pressure sensed by the second pressure sensor and the pressure sensed by the first pressure sensor may indicate the pressure differential across the SCR device 230. It should be noted that although NO x While temperature, and pressure sensors have been described as examples, sensors 250 may include other, additional, or fewer sensors than those illustrated / described herein. Other possible sensors include additive pressure sensors, flow sensors, particulate matter sensors, and the like.

[0063] In one embodiment, the control module may execute a chemical SCR model 270 that, among other things, determines the amount of reductant stored in the SCR device 230 based on signals from one or more of the first NO x (e.g. NO x -Signal from upstream NO x -Sensor 252a, also referred to as NO x1 ). The chemical SCR model 270 also predicts NO x levels of exhaust gas 206 emitted by the SCR device 230. Likewise, the chemical SCR model 270 can also predict the NO x-content of the exhaust gas 206 emitted into the atmosphere. The chemical SCR model 270 may be implemented by the control module 260. The chemical SCR model 270 may be updatable by one or more process values ​​over time. The control module 260 monitors the reductant storage level predicted by the chemical SCR model 270 and compares it to a desired reductant storage level based on the conditions of the exhaust gas 206 exiting the second LNT / LNTF device 220 and the SCR device 230.Deviations between the predicted reductant storage level and the desired reductant storage level may be continuously monitored and used to make corrections in the emissions control system 34 and in the operation of the first LNT device 210 and the second LNT / LNTF device 220 to maintain or optimize the reductant (NH3 generation in the first LNT device 210 and / or the second LNT / LNTF device 220) in a manner that enables optimal operation of the passive SCR device 230. A desired conversion rate may be determined by many factors, such as the characteristics of the SCR catalyst type and / or the operating conditions of the system (e.g., operating parameters of the ICE system 20, characteristics of the first LNT device 210, characteristics of the second LNT / LNTF device 220).

[0064] In one embodiment, the control module 260 may also execute one or more LNT chemical models 280 corresponding to the first LNT device 210 and / or the second LNT / LNTF device 220, which, among other things, may determine the NO stored in the first LNT device 210 and / or the second LNT / LNTF device 220. x -amount predicted. The predicted stored NO x based on signals from one or more of the first NO x -Sensors (e.g. the NO x -Signal from upstream NO x sensor 252a) and the first temperature sensor 254a. The chemical LNT model 280 further predicts NO x levels of the exhaust gas 206 emitted by the first LNT device 210 and the second LNT / LNTF device 220. The predicted stored NO x based on signals from one or more of the second NO x -Sensors (e.g. the NO x -Signal from NO xsensor 252b, 252c) and the temperature sensors 254b, 254c. Likewise, the chemical LNT model 280 can also measure the NO x -content of the exhaust gas 206 emitted into the atmosphere. The chemical LNT model 280 may be updatable by one or more process values ​​over time.

[0065] The control module 260 monitors the NO predicted by the LNT chemical model 280 x content and controls the emission control system 34 to execute a regeneration or purge request for the first LNT device 210 and / or second LNT / LNTF device 220 when the predicted NO x -storage levels exceed a selected threshold. In one embodiment, the selected threshold is 75% of the storage capacity for the LNT device (e.g., the first LNT device 210 or the second LNT / LNTF device 220). The stored NO x-Levels are predicted by the chemical LNT model 280 as well as by monitoring the various NO x -Sensors 252a-e measured. A "DeNO xA fuel-rich event or regeneration of the first LNT device 210 and / or the second LNT / LNTF device 220 involves operating the ICE system 20 in a fuel-rich state for a selected duration. In one embodiment, a fuel-rich state means an air / fuel ratio of less than one. More specifically, in one embodiment, an air / fuel ratio of 0.95 is used. In one embodiment, an existing oxygen sensor upstream of the LNT devices 210, 220 is employed to monitor the fuel ratio of the ICE system 20. In other embodiments, the air / fuel ratio may be predicted by a model as part of the control of the ICE system 20. In another embodiment, the selected duration is approximately ten seconds, although other durations are possible. The selected duration is based on the temperature, construction, and properties of the LNT substrate 214, 224, the NOx -storage in the LNT devices 210, 220, the velocity of the exhaust gases 206 and the stability of the combustion.

[0066] In addition, the NO x Storage also depends on the operating temperature of the first LNT device 210 and / or the second LNT / LNTF device 220. It is understood that for effective regeneration, it is desirable to maintain the ICE system 20 in a stabilized state. In particular, to ensure that the exhaust gases 206 and their content, the temperature, are in steady state. As explained herein, fluctuations in the torque demand for the ICE lead to significant fluctuations in the NO x-production. Such fluctuations complicate regeneration and, in particular, quantify the effectiveness of the regeneration. For this purpose, two methods are used to facilitate the regeneration of the first LNT device 210 or the second LNT / LNTF device 220. First, the temperatures of the first LNT device 210 and / or the second LNT / LNTF device 220 are maintained at a steady-state temperature, which ideally exceeds the NO x Storage during operation and regeneration during regeneration of the first LNT device 210 and / or the second LNT / LNTF device 220 is most beneficial. Second, torque stabilization of the ICE system 20, as described herein, to facilitate complete regeneration of the first LNT device 210 and / or the second LNT / LNTF device 220.

[0067] Deviations between the predicted NO x -Storage level and the desired NOx Storage levels can be continuously monitored and used to make corrections in the emissions control system 34 and in the operation of the first LNT device 210 and the second LNT / LNTF device 220 to maintain or optimize the NO x storage, NH3 production to facilitate further NO x -reductions in the SCR device 230 and ultimately emissions from the vehicle 10 within acceptable levels.

[0068] As previously described, the control module 260 monitors the operation of the first LNT device 210, the second LNT / LNTF device 220, the SCR device 230, and the DOC device 240 to ensure efficient operation of the emissions control system 34 while maintaining acceptable emissions. In particular, the emissions control system 34 monitors NO x- and HC emission levels. Likewise, the control module 260 controls the regeneration timing for the first LNT device 210 and second LNT / LNTF device 220 under selected operating conditions for the ICE system 20 and the emissions control system 34, ensuring that exhaust emissions are maintained at an acceptable level. For example, insufficient regeneration within the emissions control system 34 may result in undesirable emissions of NO x Species (NO x breakthrough) from the emission control system 34 (e.g. via a vehicle exhaust pipe), while excessive regeneration can lead to excessive hydrocarbon emissions, as well as NO x which passes through the SCR device 230 unreacted or the SCR device 230 as unreacted NO x leaves.

[0069] Accordingly, the engine controller 103 or the control module 260 controls, with reference to the Fig. 1 and Fig. 2 and now also on Fig. 5 illustrates the operation of the emissions control system 34 based on the selected or limited operation of the vehicle 10 and the ICE system 20. As described herein, the emissions control system 34 operates by storing NO x in the first LNT device 210 or second LNT / LNTF device 220. Eventually, however, the substrate 214 of the first LNT device 210 and / or the substrate 224 of the second LNT / LNTF device 220 becomes saturated and loses its effectiveness for adsorbing NO xTo prevent such saturation, the substrates 214, 224 must be regenerated, either by rich engine operation or by additional heating applied by the first heater 208 or the optional second heater 218 for the first LNT device 210 or second LNT / LNTF device 220, respectively. However, the regeneration of both LNT devices 210, 220 can be negatively affected by the continued operation of the ICE system 20, particularly under different operating conditions of the ICE system 20.

[0070] To address this problem, in one embodiment, the controller 103 performs a process 200 to detect excessive NO x-generation during operation of the ICE system 20 and to keep the torque of the ICE 20 substantially constant. The method 500 is implemented, in one or more examples, by one or more of the charge controller 111, engine controller 103, or control modules 260. Alternatively, the method 500 is implemented by one or more electrical circuits. In one or more examples, the method is implemented by executing logic that may be provided or stored in the form of computer-readable and / or executable instructions. In one embodiment, the process 500 initiates, while monitoring the operation of the torque request (e.g., from the operator) for the vehicle 10, as illustrated in process block 502. High torque requests (e.g., acceleration) typically result in high fuel consumption and, therefore, high exhaust emissions. As a result, the higher level of exhaust formation 206 results in higher NO xlevels in the exhaust gases 206. In addition, the requirements of the emissions control system 34 are also monitored to determine whether a regeneration event is required or in progress for either the first LNT device 210 or the second LNT / LNTF device 220, as illustrated in process block 504.

[0071] To meet these maximum operator torque requirements, method 500, in one embodiment, controls the engine torque demanded by the ICE system 20 to a selected limit. In one embodiment, the vehicle 10 employs a control scheme that limits the torque peaks demanded by the ICE system 20. This torque peak coverage avoids operating conditions for the ICE system 20 that would cause significant NO x-production, and thus places the greatest load on the emissions control system 34 to ensure acceptable emissions. The method 500 also allows the ICE system 20 to be instructed to operate at a lower torque value than the current required torque, as illustrated in process blocks 530 and 550. The lowered torque limit may be selected based on the current operating conditions of the vehicle 10, the current torque request, a preselected limit, and the like. At the same time, the engine controller 103 controls the electric motor 105 to compensate for the difference between the required torque and the preselected value, as illustrated in process block 520, to avoid a noticeable difference for the user of the vehicle 10. Finally, at process block 540, the torque difference is maintained by the electric motor 105.Accordingly, the control module 260 and the engine controller 103 control a combination of the torque of the ICE system 20 and the electric motor 105 to produce a limited NO. x generation under a wider range of operating conditions. This approach then facilitates maintaining emissions at an acceptable level and adequate regeneration of the first LNT device 210 and / or the second LNT / LNTF device 220.

[0072] In continuation of Fig. 5, when regeneration of the first LNT device 210 or the second LNT / LNTF device 220 is required or in process, the control system for the ICE system 20 commands the ICE system 20 to operate at a fixed torque at a preselected value that is less than the current demand, as illustrated in process blocks 530 and 550. The preselected torque limit may be selected based on the current operating conditions of the vehicle 10, a predetermined limit, and the like. In some embodiments, the preselected value may be zero or a setpoint. Simultaneously, the engine controller 103 commands the electric motor 105 to compensate for the difference between the required torque and the preselected value, as illustrated in process block 220. Finally, at process block 540, the torque difference is maintained by the electric motor 105.Accordingly, the control module 260 and the controller 103 control an amount and timing of regeneration of the first LNT device 210 and / or the second LNT / LNTF device 220 to ensure effective regeneration of the first LNT device 210 and / or the second LNT / LNTF device 230.

[0073] The technical solutions described here facilitate improvements to emission control systems used in internal combustion engines such as those used in vehicles. The technical features described here make it easier for the emission control system to achieve NO x -reduction in an emission control system in which an electrically heated low NO x-trap is connected in series with a passive SCR device under selected operating conditions. The selected conditions include the use of a diesel-electric hybrid system configuration with a control module configured to limit regeneration to selected instances of diesel operation. In some systems, operation is enhanced by the use of a second, optionally heated, low NO x -Trap further improved to reduce NO x -separation. In addition, control algorithms are used to facilitate peak coverage during high torque requirements, which typically lead to high NO x emissions. In addition, a torque control algorithm is implemented that allows the ICE to maintain a substantially steady-state torque condition to facilitate the regeneration of one or both LNT devices.

[0074] In terms of hardware architecture, such a computing device may include a processor, memory, and one or more input and / or output (I / O) interfaces communicatively coupled via a local interface. The local interface may include, for example, but is not limited to, one or more buses and / or other wired or wireless connections. The local interface may include additional elements omitted for simplicity, such as controllers, buffers, drivers, repeaters, and receivers, to enable communication. In addition, the local interface may include address, control, and / or data connections to enable appropriate communication between the aforementioned components.

[0075] When the computing device is in operation, the processor may be configured to execute software stored in memory, transfer data to and from memory, and generally control the functions of the computing device according to the software. Software in memory, in whole or in part, is read by the processor, possibly buffered in the processor, and then executed. The processor may be a hardware device for executing software, particularly software stored in memory. The processor may be a custom-made or off-the-shelf processor, a central processing unit (CPU), an auxiliary processor among several processors connected to the computing device, a semiconductor-based microprocessor (in the form of a microchip or chipset), or generally any device for executing the software.

[0076] Memory may include any one or a combination of volatile storage elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and / or non-volatile storage elements (e.g., ROM, hard disk, tape, CD-ROM, etc.). Additionally, memory may include electronic, magnetic, optical, or other types of storage media. Note that memory may also have a distributed architecture, with different components located remotely from each other but accessible by the processor.

[0077] The software in memory may include one or more separate programs, each containing an ordered collection of executable instructions for implementing logical functions. A system component embodied as software may also be designed as a source program, executable program (object code), script, or any other unit containing a set of instructions to be executed. When constructed as a source program, the program is translated using a compiler, assembler, interpreter, or the like, which may or may not be contained in memory.

[0078] Please note that Fig.5 illustrates the architecture, functionality, and / or operation of a possible implementation of the software. In this regard, one or more of the blocks may represent a module, segment, or section of code comprising one or more executable instructions to implement the specified logical function(s). It should also be noted that in some alternative implementations, the functions mentioned in the block may not occur in the order specified. For example, two blocks illustrated in succession may in fact execute substantially concurrently, or the blocks may execute partially in reverse order depending on the respective functionality.

[0079] It should be noted that any of the functionality described herein may be embodied in any computer-readable medium for use by or in connection with an instruction-executing system, device, or apparatus, such as a computer-based system, a processor-containing system, or any other system capable of retrieving and executing instructions from the instruction-executing system, device, or apparatus. In the context of this document, a "computer-readable medium" includes storing, transmitting, distributing, and / or transporting the program for use by or in connection with the instruction-executing system, device, or apparatus. The computer-readable medium may be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or apparatus.More specific examples (a non-exhaustive list) of a computer-readable medium are a portable computer diskette (magnetic), random access memory (RAM) (electronic), read-only memory (ROM) (electronic), erasable programmable read-only memory (EPROM or flash memory) (electronic), and portable read-only memory (CD-ROM) (optical).

Claims

[1] Emission control system (34) for exhaust gas treatment in a hybrid motor vehicle (10) with a NO x -generating internal combustion engine (26) and an electric motor (105), wherein both the internal combustion engine (26) and the electric motor (105) are designed to provide a torque that is operatively coupled to a drive train (106) of the vehicle (10), the emissions control system (34) comprising: a first electric heating device (208) operatively disposed in an exhaust conduit (204) operatively connected to the internal combustion engine (26), the exhaust conduit (204) carrying the exhaust gas (206); a first NO x -storage catalyst (LNT device) (210) arranged in the exhaust line (204) downstream of the first electric heating device (208); a second LNT device (220) disposed in the exhaust line (204) downstream of the first LNT device (210); a passive selective catalytic reduction (SCR) device (230) disposed in the exhaust conduit (204) downstream of the second LNT device (220); a hydrocarbon oxidation catalyst device (240) disposed in the exhaust conduit (204) downstream of the passive SCR device (230); a second electric heating device (218) arranged in the exhaust line (204), the second electric heating device (218) being configured to facilitate the regeneration of the second LNT device (220), the SCR device (230), and / or the hydrocarbon oxidation catalyst device (240); and a controller (103) operatively connected to the first electric heating device (208), wherein the first NO x-Sensor (252a), the first temperature sensor (254a) and the controller (103) for executing a method for controlling the NO x -Emissions of NO x -generating internal combustion engine (26), the method comprising: Monitoring a torque request for the vehicle (10); Determine if the torque request is large enough to cause combustion, NO x that exceeds a preselected threshold; Operating the internal combustion engine (26) at a reduced torque that is less than the torque requirement; and Operating the electric motor (105) with the internal combustion engine (26) to provide sufficient torque to meet the torque request, wherein the reduced torque in addition to the sufficient torque is equal to the torque request. [2] The emission control system (34) of claim 1, wherein the controller (103) is configured to perform a method further comprising: Determining whether regeneration of the first LNT device (210) is required or in process; Operating the internal combustion engine (26) at a reduced torque that is less than the torque requirement; and Operating the electric motor (105) with the internal combustion engine (26) to provide sufficient torque to meet the torque request, wherein the reduced torque in addition to the sufficient torque is equal to the torque request. [3] The emissions control system (34) of claim 2, wherein the reduced preselected torque is based on at least one of an operating condition of the vehicle (10), an operating condition of the internal combustion engine (26), and the torque request. [4] The emissions control system (34) of claim 1, wherein the reduced torque is based on at least one of an operating condition of the vehicle (10), an operating condition of the internal combustion engine (26), and the torque request. [5] The emissions control system (34) of claim 1, wherein the first electrical heating device (208) is configured to facilitate regeneration of the first LNT device (210), the second LNT device (220), the passive SCR device (230), and / or the hydrocarbon oxidation catalyst device (240). [6] The emissions control system (34) of claim 1, wherein the second LNT device (220), the passive SCR device (230) and / or the hydrocarbon oxidation catalyst device (240) comprises a particulate filter. [7] The emission control system (34) of claim 1, further including a temperature sensor (254a) operatively connected to the controller and in fluid communication with the exhaust gas (206), and / or a NO x -Sensor (252a) operatively connected to the controller (103) and in fluid communication with the exhaust gas (206). [8] A method for treating exhaust gas (206) produced by a NO x -generating internal combustion engine (26) in a hybrid vehicle (10) having an electric motor (105), wherein both the internal combustion engine (26) and the electric motor (105) are designed to provide torque that is operatively coupled to a drive train (106) of the vehicle (10), the method comprising: operatively arranging a first electric heating device (208) in the exhaust gas (206) transported by an exhaust line (204) operatively connected to the internal combustion engine (26); functional arrangement of a first NO x -storage catalyst (LNT device) (210) arranged in the exhaust line (204) downstream of the first electric heating device (208); operatively arranging a second LNT device (220) in the exhaust conduit (204) downstream of the first LNT device (210); operatively disposing a passive selective catalytic reduction (SCR) device (230) in the exhaust conduit (204) downstream of the second LNT device (220); operatively arranging a hydrocarbon oxidation catalyst device (240) in the exhaust conduit (204) downstream of the passive SCR device (230); operatively arranging a second electrical heating device (218) in the exhaust conduit (204) and facilitating the regeneration of the second LNT device (220), the SCR device (230) and / or the hydrocarbon oxidation catalyst device (240) with the second electrical heating device (218); operatively connecting a controller (103) to the first electric heating device (208), the controller (103) being configured to implement a method for controlling the NO x -Emissions of NO x -generating internal combustion engine (26), the method comprising: Monitoring a torque request for the vehicle (10); Determine if the torque request is large enough to cause combustion, NO x that exceeds a preselected threshold; Operating the internal combustion engine (26) at a reduced torque that is less than the torque requirement; and Operating the electric motor (105) with the internal combustion engine (26) to provide sufficient torque to meet the torque request, wherein the reduced torque in addition to the sufficient torque is equal to the torque request. [9] The method of claim 8, wherein the controller (103) executes a method further comprising: Determining whether regeneration of the first LNT device (210) is required or in process; Operating the internal combustion engine (26) at a reduced torque that is less than the torque requirement; and Operating the electric motor (105) with the internal combustion engine (26) to provide sufficient torque to meet the torque request, wherein the reduced torque in addition to the sufficient torque is equal to the torque request.

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