INTERNAL COMBUSTION ENGINE

摘要

A reciprocating internal combustion engine is described wherein each cylinder has an exhaust valve (104) and two intake valves (112), (122) connected to separate intake ports (111), (121). A variable valve timing system allows the overlap period between the intake and exhaust events to be extended, and means are provided for ensuring that the resulting internal EGR gases are stored significantly more in one of the intake ports than in the other. The EGR gases are directed preferentially into one (111) of the intake ports either by arranging for its intake valve (112) to open earlier than the other intake valve (122) and/or by placing an obstruction (131) to back flow in the other intake port (121).