Evaporative Emission Control through FuelShield~(TM) Gasket Technology

摘要

There are a multitude of engine interfaces which are being sealed with elastomeric gasket materials. Ever tightening evaporative emission standards require sealing materials with improved hydrocarbon permeation resistance. While this requirement is obvious for fuel sealing components, it is also applicable to engine oil sealing applications. Fuel dilutions of 5 to 10 % in the engine oil are considered the norm for most internal combustion engines. Dilution rates could be 15 to 20 % or even higher under aggressive driving or testing conditions. For fuel or fuel vapor sealing applications like fuel sender gaskets or intake manifold gaskets, compounds based on fluorocarbon rubber (FKM/FPM) are the materials of choice where low hydrocarbon emissions are desired. Engine oil sealing applications, like oil pan gaskets, valve cover gaskets and other miscellaneous oil sealing gaskets, commonly utilize less costly materials. These could be based on acrylic polymers (ACM, AEM, EVM) or hydrogenated nitrile polymers (HNBR). This paper presents a proprietary surface modification which reduces hydrocarbon emissions through cost effective elastomeric materials, while leaving their bulk material properties unchanged. FuelShield~TM makes it possible to fill the gap in permeation resistance between compounds based on acrylic polymers and those based on fluoroelastomers.