Patent ID: 8276371

Claim:
A method of treating exhaust gases in an exhaust system of an internal combustion engine comprising the steps of: receiving exhaust gases within an exhaust manifold of the internal combustion engine at an engine-out ratio of NO 2 to NO and containing a first amount of NOx; conveying the exhaust gases from the exhaust manifold to a particulate filter in an upstream segment of the exhaust system via a section of the exhaust system free from catalyst, such that the exhaust gases enter the particulate filter at the engine-out ratio of NO 2 to NO; increasing the ratio of NO 2 to NO via a catalyst within the upstream segment from the engine-out ratio toward a target ratio of NO 2 to NO for reducing NOx in a NOx reducing element within a downstream segment of the exhaust system; limiting increasing the ratio of NO 2 to NO within the upstream segment via a distribution of the catalyst in the upstream segment, which is linked to the target ratio; filtering the exhaust gases during each of the increasing step and the limiting step via a first, inlet section of the particulate filter having a coating containing the catalyst, and a second, outlet section which is bare, and wherein a length of the coating defines the distribution of the catalyst; producing an amount of NO 2 sufficient to regenerate the particulate filter, during the step of increasing; conveying the exhaust gases from the particulate filter to the NOx reducing element at the ratio of NO 2 to NO resulting from the steps of increasing and limiting; and reducing NOx in the exhaust gases via the NOx reducing element, such that the NOx is decreased from the first amount to a second amount within the downstream segment.