The hot exhaust gases containing the soot particles are fed into the filter housing where they then flow through the porous metal foil. The gaseous components flow through the microscopic pores of the filter material; the soot particles, including the ultra-fine particles, are trapped on the surface and deposited on the individual filter pockets.
Regeneration (cleaning) of the filter starts when the exhaust gas temperature reaches approximately 200°C. The nitrogen dioxide (NO2) formed with the help of the oxidation catalytic converter (oxi-cat) comes into contact with the soot deposited on the filter pockets, causing the soot particles to oxidise and degrade; the NO2 is then reduced to nitrogen oxide (NO). This chemical process is repeated continuously so that the HJS City-Filter® regenerates itself continuously, requiring no additional regeneration aids, such as assistance from the engine management system.
Last update on 2013-07-05 by Dominique Winkler.