Patent FR-2951651-A1 (FR)
Title: Ceramic filtering body for filtrating exhaust gas from an internal combustion engine e.g. diesel engine of a motor vehicle, comprises filtering blocks comprising set of adjacent channels extending between feeding and discharge faces
Inventor: RODRIGUES FABIANO
IPC: B01D46/24
Filed: 2009-10-28
Abstract: The ceramic filtering body (3) comprises filtering blocks comprising set of adjacent channels (14) extending between feeding faces and discharge faces and separated by filtering walls. The channels are sealed by upstream and downstream plugs arranged alternately near the feeding face and discharge face. The first and second filtering blocks comprise first and second external walls defining first and second internal faces and first and second outer faces. The first and second external faces and the first and second seal faces are bonded to one another by a joint (27). The ceramic filtering body (3) comprises filtering blocks comprising set of adjacent channels (14) extending between feeding faces and discharge faces and separated by filtering walls. The channels are sealed by upstream and downstream plugs arranged alternately near the feeding face and discharge face. The first and second filtering blocks comprise first and second external walls defining first and second internal faces and first and second outer faces. The first and second external faces and the first and second seal faces are bonded to one another by a joint (27). The first and second external walls and the joint are configured so that the relative difference in inter-block heat resistance between first and second measurement locations with respect to the joint is greater than 200%, where the inter-block resistance is the specific heat resistance measured by the thickness of the seal between the first and second inner faces. The joint comprises first and second regions of cements having first and second heat conductivities respectively, where the first heat conductivity is 25% greater than the second heat conductivity at a temperature of 20-600[deg] C. The joint fills a space between the first and second joint faces, and comprises a first region extending longitudinally from the feeding face over a length of 30% greater than the length of the joint, where the heat conductivity is constant on the thickness at any point of the joint. The first and second filtering blocks having heat conductivity of less than 10 W/m[deg] C. The composition of the joint is uniform on its thickness and heterogeneous along the direction of its length or width. The porosity of the joint at the first measurement location is different from the porosity of the joint in the second measurement location. In one of the first and second measurement locations, the joint has pores having an equivalent diameter of 200 microns to 20 mm such that in a cross sectional plane, the total area occupied by the pores is more than 15% of the observed total area. The joint has areas of lower adherence or non-adherence on one of the first and second joint faces or on both joint faces. The first and second measurement locations are aligned along the direction of the joint width. The inter-block resistance is further variable along the length of the joint. The first and second measurement locations are located near the longitudinal axis of the joint and near a longitudinal edge of the joint, respectively. The inter-block resistance at measuring location located near longitudinal axis is greater than that measured in location located near first and second longitudinal edge of the joint. The first and second measuring location is localized near first and second filtering blocks. The interblock resistance opposite to the joint is higher, near the first and second filtering blocks and lower at any other measurement location opposite to the joint. An independent claim is included for a process for fabricating a ceramic filtering body.