System for controlling regeneration of an adsorber

#The present invention relates generally to exhaust treatment for an internal combustion engine and more particularly, but not exclusively, to a method, system, and software utilized to determine when to stop providing reductant to a NOx adsorber while operating in a regeneration mode.

#The Environmental Protection Agency (“EPA”) is working aggressively to reduce pollution from new, heavy-duty diesel trucks and buses by requiring them to meet tougher emission standards that will make new heavy-duty vehicles up to 95% cleaner than older vehicles. Emission filters in the exhaust gas systems of internal combustion engines are used to remove unburned soot particles from the exhaust gas and to convert harmful pollutants such as hydrocarbons (“HC”), carbon monoxide (“CO”), oxides of nitrogen (“NOx”), and oxides of sulfur (“SOx”) into harmless gases.

#NOx storage catalyst units or adsorbers are used to purify exhaust gases of combustion engines. Generally speaking, these NOx storage catalyst units store or trap NOx while the engine is operating in a lean mode and remove NOx from the adsorber while the engine is operating in a rich mode. One of the necessary steps to regenerate a respective adsorber is to consume all of the oxygen on the surface of the catalyst (referred to as the oxygen storage component (“OSC”)). Before the oxygen on the surface of the adsorber can be consumed, the oxygen in the exhaust gas produced by the engine must first be consumed. Once this is accomplished, any additional reductant supplied will be used to consume the OSC on the surface of the adsorber and to regenerate the adsorber. Accordingly, there is a need for methods and systems for determining how much reductant should be supplied to an adsorber in order to properly regenerate the adsorber.

#FIG. 1 is a schematic of a representative diesel engine system;

#FIG. 2 is a more detailed schematic of the exhaust system of the representative diesel engine system;

#FIG. 3 is a block diagram illustrating an after-treatment manager module and a combustion manager module executable by the control unit;

#For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention is illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

#With reference to FIG. 1, there is illustrated, schematically, a system 10 that includes an internal combustion engine 12 operatively coupled with an exhaust filtration system 14. The exhaust filtration system 14 includes a diesel oxidation catalyst (“DOC”) unit 16, a NOx adsorber or Lean NOx trap (“LNT”) 18, and a diesel particulate filter (“DPF”) 20. The exhaust filtration system 14 is operable to remove unwanted pollutants from exhaust gas exiting the engine 12 after the combustion process.

#The DOC unit 16 is a flow through device that consists of a canister that may contain a honey-comb like structure or substrate. The substrate has a large surface area that is coated with an active catalyst layer. This layer may contain a small, well dispersed amount of precious metals such as, for example, platinum or palladium. As exhaust gas from the engine 12 traverses the catalyst, CO, gaseous HC and liquid HC particles (unburned fuel and oil) are oxidized, thereby reducing harmful emissions. The result of this process is that these pollutants are converted to carbon dioxide and water. In order to function properly, the DOC unit 16 must be heated to a minimum temperature value.