Abstract: A partial wall-flow filter, having a honeycomb structure including an inlet end, an outlet end, and parallel channels disposed and configured to flow fluid from the inlet end to the outlet end. The channels are defined by a plurality of intersecting porous walls. The partial wall-flow filter has a filtration region of channels plugged at the outlet end and a bypass region of unplugged channels. An N/S ratio of the filter material is less than or equal to about 0.5, less than or equal to about 0.3, less than or equal to about 0.1, or even 0, where N is a pressure drop difference induced by deep bed soot and S is a pressure drop change from 0 grams per liter (g/l) to about 5 g/l for a conditioned curve induced by cake bed soot, where N and S are measured on a full wall-flow filter of the filter material.

Abstract: A thin-walled porous ceramic wall-flow filter is disclosed. The filter produces a relatively lower pressure drop coupled with relatively high initial filtration efficiency (FE0), and may enable packaging the filter in a smaller volume. The filter includes a plurality of porous ceramic walls forming cell channels. At least some of the cells are plugged forcing some exhaust gases through the walls, thereby filtering out entrained particulates. The walls have a wall thickness (Twall) wherein 102 ?m?Twall<279 ?m, and a median pore diameter (MPD), and wherein 10<Twall/MPD, and may also be <40. The relatively small median pore diameter (MPD) in comparison to the wall thickness (Twall) allows the use of thinner ceramic walls that provide less flow resistance than thicker walls while maintaining sufficient initial filtration efficiency (FE0). Furthermore, such thin-walled filter structure coupled with unequal inlet/outlet area ratio (Ai/Ao) may allow filter lengths to be additionally shortened.

Abstract: Systems and methods for controlling temperature and total hydrocarbon slip in an exhaust system are provided. Control systems can comprise an oxidation catalyst, a particulate filter, a fuel injector, and a processor for controlling a fuel injection based on an oxidation catalyst model. Example system includes a virtual sensor comprising a controller for calculating and providing the total hydrocarbon slip to subsystems for after-treatment management based on modeling the oxidation catalyst. Example methods for controlling the temperature and the total hydrocarbon slip in an exhaust system include the steps of providing an oxidation catalyst model, monitoring a condition of the exhaust system, calculating a hydrocarbon fuel injection flow rate and controlling a fuel injection. The example methods further include the steps of determining an error in the oxidation catalyst model based on the monitored condition and changing the oxidation catalyst model to reduce the error.

Abstract: A partial wall-flow filter has an inlet end, an outlet end, and a plurality of parallel channels disposed and configured to flow fluid from the inlet end to the outlet end. The channels are defined by a plurality of porous walls. A first portion of the channels have a first hydraulic diameter Dh1, a second portion of the channels have a second hydraulic diameter Dh2 smaller than the first hydraulic diameter Dh1, and the ratio of Dh1:Dh2 is in the range of 1.1 to 1.6. At least a portion of channels having hydraulic diameter Dh1 are plugged at the outlet end, and channels having hydraulic diameter Dh2 are flow-through channels.

Abstract: Method, apparatus, and system to control ammonia slip in a selective catalytic reduction (SCR) system. The method includes detecting an engine operation transition event, increasing NOx to the SCR catalyst, and decreasing a reductant dose. The system includes a controller to receive an engine transition signal, anticipate a temperature transition at the SCR catalyst in response to the engine transition signal, and cause a NOx increase in the exhaust gas stream to the SCR catalyst and a decrease of reductant to the SCR catalyst coinciding with the temperature transition at the SCR catalyst. The apparatus includes a NOx increase module to cause the NOx increase in the exhaust gas stream to the SCR catalyst in response to the engine transition signal. The apparatus also includes a reductant shut-off module configured to cause the reductant addition to the exhaust gas stream to turn off in response to the engine transition signal.

Abstract: A partial wall-flow filter having some unplugged flow-through channels and some plugged channels. Desirable combinations of filtration efficiency and back pressure may be provided by combinations of t wall?305 urn, MPD?20 ?m, % P?50%, and CD?250 cpsi wherein t wall is the transverse thickness of the porous walls, MPD is a mean pore diameter of the porous walls, % P is the total porosity of the porous walls, and CD is the cell density of the channels. In one embodiment, some of the plugged channels are located adjacent to the inlet end and some are located adjacent to the outlet end. Systems and method including the partial wall-flow filter are also described.

Abstract: A method of controlling the operation of a particulate filter in an exhaust gas after-treatment system may comprise calculating a ratio of particulate loading rate to filter regeneration rate using a mass-based soot load estimation scheme and comparing the ratio of particulate loading rate to filter regeneration rate to a predetermined threshold value. The method may further comprise controlling operating conditions of the particulate filter to maintain the ratio of particulate loading rate to filter regeneration rate at a value above the predetermined threshold value.

Abstract: A method for regenerating a particulate filter may comprise calculating a soot layer state correction factor based on a rate of regeneration and a rate of particulate loading in the particulate filter and calculating an estimated soot load in the particulate filter based on a pressure drop of an exhaust gas flowing through the particulate filter and the calculated soot layer state correction factor. The method for regenerating the particulate filter may further comprise causing regeneration of the particulate filter when the estimated soot load is greater than or equal to a threshold value.

Abstract: Disclosed are ceramic honeycomb articles which possess a unique microstructure characterized by porosity between 40% and 70%, and the presence of coarse pores exhibiting a depth equivalent to the thickness of the cell wall and a dimensional width, in the plane of the cell wall, exhibiting a diameter that is at least as large as the thickness of the cell wall. The articles exhibits reduced filtration efficiency coupled with low pressure drop across the filter, and a reduced regeneration need. Such ceramic articles are particularly well suited for filtration applications, such as off-road and retro-fit diesel exhaust filters or DPFs. Also disclosed is a method for manufacturing the ceramic article wherein the pore former is capable of forming coarse pores.

Abstract: A particulate filter may comprise an inlet end, an outlet end, and a plurality of parallel channels disposed and configured to flow fluid from the inlet end to the outlet end, the channels being defined by a plurality of porous walls configured to trap particulate matter. The particulate filter may define at least one filtration region including a first group of channels and at least one bypass region including a second group of channels, wherein at least some of the channels in the first group of channels are plugged at an end thereof, wherein the channels in the second group of channels are unplugged, and wherein greater than or equal to about 70% of the plurality of parallel channels are plugged at an end thereof.

Abstract: Systems and methods for controlling temperature and total hydrocarbon slip in an exhaust system are provided. Control systems can comprise an oxidation catalyst, a particulate filter, a fuel injector, and a processor for controlling a fuel injection based on an oxidation catalyst model. Example system includes a virtual sensor comprising a controller for calculating and providing the total hydrocarbon slip to subsystems for after-treatment management based on modeling the oxidation catalyst. Example methods for controlling the temperature and the total hydrocarbon slip in an exhaust system include the steps of providing an oxidation catalyst model, monitoring a condition of the exhaust system, calculating a hydrocarbon fuel injection flow rate and controlling a fuel injection. The example methods further include the steps of determining an error in the oxidation catalyst model based on the monitored condition and changing the oxidation catalyst model to reduce the error.

Abstract: Mass based methods and systems for estimating soot load in a filter of an after-treatment system for exhaust stream are provided. The after-treatment system can comprise a sensor, a filter, and a processor configured to estimate soot load in the filter based on a mass based multi-layer model. An example system includes a virtual sensor comprising an estimator for providing information corresponding to a filter outlet NO2 concentration. An example method includes the steps of providing the mass based multi-layer model, passing the exhaust stream through the filter, and using the sensor to monitor a condition of the exhaust stream. The example method further includes the steps of calculating a total regeneration rate based on the multi-layer model by solving a second-order ordinary differential equation with a plurality of parameters using an analytical approach, and estimating the soot load based on the calculated total regeneration rate.

Abstract: An exhaust gas after-treatment system (10) for a gasoline engine (12) has a three-way catalyst (14) close-coupled to the gasoline engine, a particulate matter control device (18) positioned downstream of the three-way catalyst, a NOx control system (16) positioned downstream of the particulate matter control device. According to one method of operation, the gasoline engine is operated in a stoichiometric condition upon start-up of the engine, the exhaust gas flow generated by the engine is conducted through the exhaust system, and then the gasoline engine (12) is operated in a lean-burn condition after the NOx control system (16) attains a minimum operating temperature.

Abstract: Systems and methods are provided for controlling an exhaust stream temperature at a point along an exhaust system. The exhaust system can include an oxidation catalyst, a particulate filter having an outlet, and a fuel injector for injecting fuel into an exhaust stream at a location upstream from the outlet. An adaptive control can be provided to model a portion of the exhaust system. A fuel injection flow rate at which fuel is injected into the exhaust stream by the fuel injector can be calculated based on the adaptive control model. An operation of the fuel injector can be controlled based on the calculated fuel injection flow rate, to control the exhaust stream temperature at point along the exhaust system. A condition of the exhaust stream can also monitored and an error in the adaptive control model can be determined based on the monitored condition. The adaptive control model can also be changed to reduce the error.

Abstract: A particulate filter may comprise an inlet end, an outlet end, and a plurality of channels disposed and configured to flow fluid from the inlet end to the outlet end, wherein the channels are defined by porous walls configured to trap particulate matter. The porous walls may have a cell density less than about 200 cpsi, a wall thickness of less than about 14 mils, a median pore size that ranges from about 13 micrometers to about 20 micrometers, a total porosity greater than about 45%, and a pore size distribution such that pores less than 10 micrometers contribute less than about 10% porosity.

Abstract: A particulate filter may comprise an inlet end, an outlet end, and a plurality of channels disposed and configured to flow fluid from the inlet end to the outlet end, wherein the channels are defined by porous walls configured to trap particulate matter. The porous walls may have a total porosity greater than about 45%, a median pore size ranging from about 13 micrometers to about 20 micrometers, and a pore size distribution such that pores less than 10 micrometers contribute less than about 10% porosity.

Abstract: A method for regenerating a particulate filter may comprise determining a temperature, a flow rate, and a total pressure drop of an exhaust gas flowing through a particulate filter, and determining a corrected soot layer permeability. The method may further comprise calculating an estimated soot load of the particulate filter based on the total pressure drop and the corrected soot layer permeability, and causing regeneration of the particulate filter when the estimated soot load is greater than or equal to a threshold value.

Abstract: A method of controlling the operation of a particulate filter in an exhaust gas after-treatment system may comprise calculating a ratio of particulate loading rate to filter regeneration rate using a mass-based soot load estimation scheme and comparing the ratio of particulate loading rate to filter regeneration rate to a predetermined threshold value. The method may further comprise controlling operating conditions of the particulate filter to maintain the ratio of particulate loading rate to filter regeneration rate at a value above the predetermined threshold value.

Abstract: A method for regenerating a particulate filter may comprise calculating a first estimated soot load of a particulate filter based on a pressure drop of an exhaust gas flowing through the particulate filter, and calculating a second estimated soot load of the particulate filter based on a mass balance of soot in the particulate filter. The method may further comprise calculating a hybrid estimated soot load based on the first estimated soot load and the second estimated soot load, wherein calculating the hybrid estimated soot load comprises applying at least one gate so as to weight a relative contribution of each of the first estimated soot load and the second estimated soot load to the hybrid estimated soot load, and causing regeneration of the particulate filter when the hybrid estimated soot load is greater than or equal to a threshold value.

Abstract: A method for regenerating a diesel particulate filter includes elevating a temperature of a gas stream flowing into an inlet of the diesel particulate filter to greater than or equal to 450° of the inlet of the diesel particulate filter, wherein the gas stream at the inlet of the diesel particulate filter contains an amount of NOx of equal to or greater than 300 ppm, and an amount of O2 of equal to or greater than 5% volume, thereby burning the soot within the diesel particulate filter. The method also includes elevating a temperature of the gas stream flowing into the inlet of the diesel particulate filter to less than or equal to 550° C. at the inlet of the diesel particulate filter, wherein a burn rate of soot from porous walls of the diesel particulate filter is greater than or equal to 3.8 grams/liter/hour.