ACTIVATED CARBON IMPREGNATED FOAM AS AN ADSORPTIVE FILTER MATERIALFOR AIR INDUCTION SYSTEMS

摘要

Due to the emission regulations LEV II and PZEVrnestablished by the California Air Research Board, the automotivernmanufacturers had to install additional adsorptive filter systems atrnthe carbon canisters of the tank venting system and in the airrninduction system to reduce hydro carbon emissions. Therndevelopment in the last three years has shown that for LEV IIrnapplications most of the vehicles need a hydro carbon trap for thernair induction system but only a few need the additional filter forrnthe carbon canister. The need of a hydro carbon trap for carbonrncanisters has been reduced to PZEV vehicles where the totalrnamount of allowed emissions are 350 mg per day in comparisonrnto 500 mg for LEV II. Helsa-automotive has developed solutionsrnfor both applications, air induction and carbon canister. In thisrnpaper we will focus on the air induction system. For thisrnapplication there exist many different solutions based on differentrnfilter structures and adsorptive materials. The most importantrnpoints are flow restriction, stability and of course the costs of thernfilter. Helsa-automotive has recently developed a new filterrnmaterial based on a polyether based polyurethane foamrnimpregnated with a special activated carbon. The productionrnprocess of this material is well established since many years. Thernaim of this paper is to present the features of this new filterrnmaterial and to discuss the advantages in comparison to thernexisting solutions.