Patent ID: 7537633

Claim:
A filter unit for filtering particles contained in exhaust gases of an internal combustion engine, comprising: interleaved sets of adjacent inlet passages ( 10 , 11 ) and outlet passages ( 12 , 13 ) in fluid communication through lateral walls of said inlet passages ( 10 , 11 ) and said outlet passages ( 12 , 13 ), said unit including a set of lateral wall portions ( 16 1 - 16 8 ) forming an intermediate wall ( 15 ) between said inlet passages ( 10 , 11 ) and said outlet passages ( 12 , 13 ) and having, in cross section, an undulation determined to increase an overall volume of said inlet passages ( 10 , 11 ) at an expense of an overall volume of the outlet passages ( 12 , 13 ), and the overall volume (Ve) of said inlet passages ( 10 , 11 ) being greater that the overall volume (Vs) of said outlet passages ( 12 , 13 ), wherein, a hydraulic diameter of said outlet passages ( 12 , 13 ) is from 0.9 to 1.4 mm, a ratio r of the overall volume (Ve) of the inlet passages ( 10 , 11 ) to the overall volume (Vs) of the outlet passages ( 12 , 13 ) is from 1.15 to 4, a filtering area is from 0.825 m 2 to 1.4 m 2 per liter of said filter unit, and a ratio of asymmetry of said undulation is less than 15% and greater than 5%.