ACTIVATED CARBON IMPREGNATED FOAM AS AN ADSORPTIVE FILTER MATERIAL FOR AIR INDUCTION SYSTEMS

摘要

Due to the emission regulations LEV II and PZEV established by the California Air Research Board, the automotive manufacturers had to install additional adsorptive filter systems at the carbon canisters of the tank venting system and in the air induction system to reduce hydro carbon emissions. The development in the last three years has shown that for LEV II applications most of the vehicles need a hydro carbon trap for the air induction system but only a few need the additional filter for the carbon canister. The need of a hydro carbon trap for carbon canisters has been reduced to PZEV vehicles where the total amount of allowed emissions are 350 mg per day in comparison to 500 mg for LEV II. Helsa-automotive has developed solutions for both applications, air induction and carbon canister. In this paper we will focus on the air induction system. For this application there exist many different solutions based on different filter structures and adsorptive materials. The most important points are flow restriction, stability and of course the costs of the filter. Helsa-automotive has recently developed a new filter material based on a polyether based polyurethane foam impregnated with a special activated carbon. The production process of this material is well established since many years. The aim of this paper is to present the features of this new filter material and to discuss the advantages in comparison to the existing solutions.