The IP Filter, a DOC-Integrated DPF, for an Advanced PM Aftertreatment System (2): An Evaluation of Fundamental Performance 2007-01-0654

DPR consists of a multiple fuel-injection system, an electronic engine control unit, and a DPR Cleaner. The DPR cleaner is one assembly unit consisting of a DOC, a catalyzed DPF, and an exhaust silencer. Thus, DPR is a system developed to achieve healthy operation of a DPF with active regeneration regardless of engine operating conditions.

The IP Filter was developed to improve the DPR cleaner by reducing the size of the unit and shortening the regeneration time. Both the DOC and DPF are integrated into one unit structure. The IP Filter has open-ended cells on the front face unlike a conventional wall-flow DPF. Instead, the plugs are positioned at the interface between the DOC and DPF. On the rear face of the IP Filter, plugs are installed at the same positions as those of a conventional DPF. The DOC substrate of the IP Filter is made of highly porous, straight honeycomb, the same as that of DPF. Thus, the DOC part of the IP Filter not only functions as an oxidation catalyst, but also as a DPF.

This paper reports the fundamental performance results of the IP Filter which were evaluated through engine tests under step-transient operating conditions including idle for the characteristics of temperature profile and response, particulate loading, and differential pressure. The IP Filter increased filtration efficiency, reduced differential pressure, and increased temperature response. Because of the internal plugs in the IP Filter, the maximum allowable soot loading could be higher than that of a conventional wall-flow DPF. Consequently, the test results indicated that not only can the IP Filter reduce the size of DPR Cleaner for increased flexibility of installation, but also the active regeneration and the differential pressure across the filter could be improved for better fuel economy.