Apparatus for preventing valve stem coking

摘要

An exhaust gas recirculation valve having a reciprocating pintle shaft supported by a sleeve bushing and having a labyrinthine pathway between a valve operating chamber and a shaft/bushing interface to minimize intrusion of exhaust gases into the interface. The labyrinthine pathway is formed between fixed annular elements of the valve body and shaft bushing and a movable annular element of the valve head telescopically disposed between the fixed elements.