| 摘要 |
The present invention relates to particulate filters for diesel engines based on matel foams.In order to achieve high filtration efficiency with low pressure drop using deep bed filtration metal foams, a radial flow concept is used based on a "porosity gradient". The foams can also be coated with catalytically active material to anhance soot axidation (regeneration), as well as reducationof other exhaust gas pollutants (CO, hydrocarbons, nitrogen oxides). This could be preferentially accomplishe by using non-uniform amounts of catalytic materials with in the filter depenting on the targeted application. In a preferred embodiment, an additional (secondary) filter depending on the targeted application. In a preferred embodiment, an additional (secondary) filter segment (13) is plased with in the metal support of the main filter segment(8). The metallic diaphragms (11,12,16) at the entrance and exit of the external shell (1) are designed in such a way as tp allow the flow to be divided between the main (8) and the secondary (13) filter segments according to the respective flow resistances. In a variation of the proposed invention the filter can be designed in such a way as to ensure very high filtration efficiency when clean and ensure a non-blocking behavior in case the soot loading in the filter reaches extremely high values due varius reasons (e.g. prolonged low temperature operetion). |
