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A new method has been developed to close the ends of a wall flow filterused for removing particulate matter from diesel engine exhaust. In thismethod, the ends of the honeycomb structure are capped by deforming andclosing the ends of the channel walls between the extrusion and firingstages of production. The method increases the amount of filtration area per filter volume for agiven cell geometry conpared to the traditional plugging method, since theentire length of the honeycomb channels is used for filtration purposes. In addition, use of the capping method has a beneficial effect on thepressure loss characteristics of a filter with a given filtration area.These benefits are illustrated through experimental results.

Many of the materials which have been developed for use as particle filters in the exhaust of diesel engines have characteristics which give rise to significant problems in practical use. Due to its special characteristics, it is shown that SiC is very well suited for use as the base material for particulate filters. The physical and thermal properties of porous SiC substrate material as applied to diesel particulate filters have been determined and are presented. Experimental results from several types of filter regeneration processes in exhaust gas systems confirm the improvements in the area of thermal load and reduction in temperature level during regeneration. The reduction in temperature during regeneration is shown to be consistent with the high thermal conductivity of SiC.