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 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:
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:
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:
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:
A exhaust system and method for venting exhaust from an engine, such as a diesel engine, through an exhaust line coupled to the engine includes a first particulate filter disposed in the exhaust line and “close-coupled” with the engine, and a second particulate filter spaced a distance (d) from the first filter. The first particulate filter is “close-coupled” so that it operates in a passive regeneration mode to a greater extent than the second particulate filter. The first particulate filter may be a partial wall-flow filter including some plugged and some open channels. Some of the plugged channels may be plugged adjacent to an inlet end and others may be plugged adjacent to an outlet end. A partial wall-flow filter is also described having some unplugged flow-through channels and some plugged channels wherein some plugged channels are located adjacent to the inlet end and some are located adjacent to the outlet end.
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:
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 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 μm, % 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:
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.