Tuning particulate filter performance through selective plugging and use of multiple particulate filters to reduce emissions and improve thermal robustness

An exhaust aftertreatment system for filtering engine exhaust flowing along an axial direction, said system comprising at least a first and a second filter arranged in series along said axial direction, said first filter being positioned upstream of said second filter and having a lower filtration efficiency than said second filter, wherein at least one of said first and second filter is composed of monolithic regenerable filtration material, said material comprising an axially extending filter element having wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said wall segments being alternately sealed to each other by a first set of plugs to define a first set of flow channels closed by said plugs and having open downstream ends, and a second set of flow channels interdigitated with said first set of flow channels and having open upstream ends, said wall segments being alternately sealed to each other by a second set of plugs closing said second set of flow channels, and said wall segments further defining a third set of channels having open flow, said wall segments further defining a fourth set of flow channels having closed downstream ends and closed upstream ends, said fourth set of flow channels forming a peripheral ring in said filter, wherein said third set of flow channels are arranged in a ring adjacent to the peripheral ring formed by the fourth set of flow channels.

An exhaust aftertreatment filter for filtering engine exhaust flowing along an axial direction, said filter being composed of monolithic regenerable material and comprising an axially extending filter element having wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said wall segments being alternately sealed to each other by a first set of plugs to define a first set of flow channels closed by said plugs and having open downstream ends, and a second set of flow channels interdigitated with said first set of flow channels and having open upstream ends, said wall segments being alternately sealed to each other by a second set of plugs closing said second set of flow channels, said wall segments further defining a third set of channels having open flow, said third set of channels having selected positions in said filter for reducing back pressure on said filter during operation while maintaining filtering efficiency, said wall segments further defining a fourth set of flow channels having closed downstream ends and closed upstream ends, said fourth set of flow channels forming a peripheral ring in said filter, wherein said third set of flow channels are distributed in said filter in a gradient, said filter having an increasing concentration of open channels in sections located at peripheral positions in said filter as compared to sections located at central positions of said filter.

An exhaust aftertreatment system for filtering engine exhaust flowing along an axial direction, said system comprising at least a first and a second filter arranged in series along said axial direction, said first filter being positioned upstream of said second filter and having a lower filtration efficiency than said second filter, wherein at least one of said first and second filter is composed of monolithic regenerable filtration material, said material comprising an axially extending filter element having wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said wall segments being alternately sealed to each other by a first set of plugs to define a first set of flow channels closed by said plugs and having open downstream ends, and a second set of flow channels interdigitated with said first set of flow channels and having open upstream ends, said wall segments being alternately sealed to each other by a second set of plugs closing said second set of flow channels, and said wall segments further defining a third set of channels having open flow, said wall segments further defining a fourth set of flow channels having closed downstream ends and closed upstream ends, said fourth set of flow channels forming a peripheral ring in said filter, wherein said third set of flow channels are distributed in said filter in a gradient, said filter having an increasing concentration of open channels in sections located at peripheral positions in said filter as compared to sections located at central positions of said filter.