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Behavior of particulate accumulation/removal on porous filter was studied. Optimum elements of effective reverse cleaning regeneration were examined. DPF system with cross flow filter and pulse jet cleaning (APT) was applied to city bus application. Its trap efficiency was evaluated by California Air Resources Board. Two terms of fleet test were conducted in Los Angeles area. First test demonstrated serviceability of reverse cleaning regeneration, filter and high trap efficiency It accumulated 4340 mile and proved filter durability Size-reduced second APT had negative effect of turbulent flow to the particulate burning area.

A new particulate trap system has been developed. It features both a cross flow type ceramic filter and reverse cleaning regeneration. The filter is made up of thin plate elements of modified cordierite. Each plate has a row of some two dozen open-end, oval-sectioned channels. A periodic reverse jet cleaning by compressed air injection blows the particulate off the filter wall and drops it into the vessel bottom. It is burned by an electric heater. The trap efficiency of this system is above 95%. The durability has been confirmed by a 1000-hour test. Its efficiency will meet EPA 1994 standards with present diesel engines.