SCHICHTFORMIGE FILTERSTRUKTUR

摘要

A layered filtering structure (10) comprises at least a first layer (12) and a second layer (13). Each layer comprises a web of metal fibers which has been sintered. The two layers (12, 13) are in contact with each other. The first layer, most close to the filter inlet side has a porosity below 55 %, and the second layer, closer to the filter outlet side has a porosity which is at least 20 % greater than the porosity of the first layer. The first layer is compacted in a separate manufacturing step. The layered filtering structure combines the advantage of a small filter rating with a low pressure drop.